CN104408277B - Method for predicting, preventing and controlling earth surface residual movement and deformation caused by newly-built building in mine lot - Google Patents

Abstract

The invention provides a method for predicting and preventing residual movement and deformation of the surface when new buildings are built on the surface of the old mining area. The prediction method is based on the mining parameters obtained by the geophysical prospecting of the old mining area through the mine map or based on the geological drilling as the geophysical analysis control of the EH4 electrical conductivity imaging system before the new building, as well as the existing rock movement parameters in my country and the surface of the old mining area. When the new building is about to be built, the leveling measurement results of the surface strike line in the old mining area are carried out; the prediction targets are the residual subsidence of the surface, the residual tilt deformation of the surface, the residual curvature deformation of the surface, the horizontal movement of the residual surface and the horizontal deformation of the residual surface; Insufficient parameters at the time of prediction, problems that are difficult to promote due to the emergence of new parameters, the damage level of new buildings on the surface of old mining areas can be evaluated, and the ground (old mining area) grouting implementation method for preventing residual surface movement and deformation of new buildings can be adopted in advance. Including: the technological process, grouting materials, grout ratio, etc. of the grouting project from the ground to the goaf.

Description

Prediction and Prevention Methods of Surface Residual Movement and Deformation Caused by New Buildings in Mining Area

Technical field

The invention belongs to the field of coal mining subsidence, and relates to a method for predicting and preventing residual movement and deformation of the ground surface caused by newly built buildings above the old mining area of the coal mine.

Background technique

Coal mining causes large-scale surface subsidence, causing casualties, damage to urban buildings, lifeline systems and ecological environment, and threatening the safety of people's lives and properties. In 2000, the "Buildings, Water Bodies, Railways, and Main Shaft Coal Pillar Retention and Coal Mining Regulations" published by the Coal Industry Press stipulated that the ground surface movement starts from sinking 10 mm, and the sinking does not exceed 6 months in a row. It ends at 30 mm, and the duration of ground movement is T=2.5H ₀ , where the unit of T is day, generally 3 to 5 years; H ₀ is the average mining depth, unit: meter. However, foreign observation data show that the goaf at this time has not reached a stable level. Under the influence of external factors such as new buildings above the old mining area, the surface will continue to produce residual movement and deformation, which can cause damage to new buildings and even cause Sudden subsidence of the ground surface. When REGray and RWPruern studied the subsidence of coal seam mining in Pittsburgh, they pointed out that the subsidence of room-and-pillar mining in old goafs may occur 50 years or more after mining. The influence of surface residual movement and deformation on buildings has become a key issue in the evaluation of foundation stability.

Zhu Guangyi, the provider of the present invention, put forward the criterion for the occurrence of surface residual movement and deformation in the paper "On Urban Land Development under Shallow Mining Conditions" published in the 5th issue of "Journal of Liaoning Engineering Technology University" Natural Science Edition in 2009: The relationship between additional stress σ _z and foundation self-weight stress σ _c K _c P ₀ =0.1×(r ₁ h ₁ +r ₂ h ₂ +…+r _n h _n ) to calculate the effective depth Z. In the formula, P ₀ is the average additional pressure acting on the bottom of the foundation, r _i is the bulk density of the i-th rock layer of the foundation, h _i is the thickness of the i-th rock layer of the foundation, Kc is the vertical additional stress coefficient under the uniformly distributed rectangular load corner point, and The effective depth Z is related. Then, H _LJ is calculated by the coal mining critical depth formula H _LJ =Z+H _li +H _b , and if the criterion H _LJ >H ₀ is met, the residual movement deformation of the surface will appear. In the formula H _LJ =Z+H _li +H _b , H _LJ is the critical depth of coal mining; H _li is the maximum height of the water-conducting fracture zone in the mining area; H _b is the height of the unfillable zone, H _b =0.16H ₀ .

When the criterion H _LJ >H ₀ , there will be residual movement and deformation of the surface, the prediction method of the magnitude of the residual movement and deformation of the surface is a key issue in the evaluation of foundation stability. However, at present, the code does not have a definition of residual surface movement and deformation and a prediction method for surface residual movement and deformation; some literatures have only discussed the surface residual subsidence W _c (x), but the predecessors still have the expression of W _c (x) Due to too few parameters, it is difficult to accurately express the complex effects of overburden geological and mining factors, and it is difficult to popularize due to the emergence of new parameters; especially, the predecessors did not use the existing rock movement parameters in China to carry out surface residual tilting deformation _ic (x) , surface residual curvature deformation K _c (x), surface residual horizontal movement U _c (x), and surface residual horizontal deformation ε _c (x), because there are no _{ic (x), ε c (} x), K _c (x), but it is impossible to assess the damage level of new buildings on the surface of the old mining area according to the regulations, and it is impossible to take corresponding disaster prevention and control measures according to the damage level of the new buildings on the surface of the old mining area.

Contents of the invention

The object of the present invention is to provide a method for predicting and preventing the residual movement and deformation of the ground surface caused by newly built buildings in the mining area. Angle tangent tanβ, maximum subsidence angle θ, inflection point offset S ₁ , S ₂ , S ₃ , and S ₄ multiple rock movement parameters to accurately predict surface residual subsidence, surface residual tilt deformation, surface residual curvature deformation, and surface residual Horizontal movement and residual horizontal deformation of the surface; from this, it is possible to evaluate the damage level of newly built buildings on the surface of old mining areas, and to take corresponding measures to prevent residual movement and deformation of the surface.

Explanation of the definition of the residual movement and deformation of the surface: "Regulations for the Coal Pillar Retention and Pressure Coal Mining of Buildings, Water Bodies, Railways, and Main Shafts" stipulates that the end of the surface movement duration is that the subsidence does not exceed 30 mm for 6 consecutive months ; And the present invention is called the initial stabilization time of the earth surface when the surface sinks no more than 30 millimeters for 6 consecutive months; the earth surface movement deformation after the initial stabilization of the earth surface is called the residual movement deformation of the earth surface; the residual movement deformation of the earth surface is divided into two stages: In the first stage, after the subsidence does not exceed 30mm for 6 consecutive months, the increments of each moving deformation gradually tend to 0; in the second stage, when new buildings are built on the shallow surface of the old goaf, the The overlying rock is activated, and the mobile deformation continues to be produced on the surface. The impact of the mobile deformation on buildings at this stage is often harmful and cannot be ignored; the harmful impact of the residual mobile deformation on the ground is actually produced in the second stage. The residual mobile deformation of the surface refers to the second stage.

A method for predicting residual movement and deformation of the ground surface caused by new buildings in a mining area, the steps of which are as follows:

Step 1. If the mining depth of the working face in the old mining area is greater than 150 meters, the new buildings on the surface of the old mining area will not cause the residual movement and deformation of the surface; if the mining depth is less than or equal to 150 meters, according to the criterion H _LJ introduced in "Background Technology">H ₀ , calculate the critical depth of coal mining H _LJ , compare the critical depth of coal mining H _LJ with the average mining depth H ₀ , if the criterion H _LJ >H ₀ is satisfied, it can be determined that there will be residual movement on the surface of the old mining area Transform; continue with the following steps.

Step 2. Collect data

⑴Collection of mining data: collect working face strike length D ₃ , working face inclination length D ₁ , mining thickness M, coal seam inclination α, average mining depth H ₀ , and maximum subsidence angle θ through mining map data in the mining area.

On-the-spot investigations in the surface construction area of the old mining area; visits to professional technicians related to the old mining area such as geology, surveying, and mining, and residents of the surface construction area.

If there is no mine map, these mining parameters are obtained through the analysis of several observation lines uniformly arranged in the geophysical prospecting area by using the American EH-4 electrical conductivity imaging system Hybrid-Source Magnetotellurics; The distance between the lines depends on the geophysical prospecting accuracy, and generally it is about 10 to 20 meters; in order to prevent human misjudgment of the EH-4 conductivity imaging, more than two geological boreholes are evenly distributed in the geophysical prospecting area as the geophysical prospecting system of the EH-4 conductivity imaging system. Analytical control.

(2) Collect rock movement parameters in the mining area: subsidence coefficient q, main influence angle tangent tanβ, horizontal movement coefficient b ₁ , inflection point offset S ₁ , S ₂ , S ₃ , S ₄ , maximum subsidence angle θ.

(3) When new buildings are about to be built on the surface of the old mining area, a leveling survey of the surface trend line of the old mining area is carried out to obtain the maximum subsidence value W _m ′ of the surface at this time.

Step 3. Obtain the maximum subsidence value of the inclined main section in the following order

(1) Calculate the ordinate of the maximum surface subsidence point in the center of the goaf

In the formula, y _m is the ordinate of the maximum subsidence point on the surface of the goaf center, unit: meter; D ₁ is the inclination length of the working face, unit: meter; S ₁ is the offset distance of the inflection point on the lower side of the working face, unit: meter; θ is the maximum subsidence angle, unit: degree; α is the coal seam inclination angle, unit: degree.

(2) Calculating the maximum surface subsidence value when fully mined

W ₀ =Mqcosα

In the formula, W ₀ is the maximum subsidence value of the surface during full mining, unit: mm; M is the mining thickness, unit: mm; α is the inclination angle of the coal seam, unit: degree; q is the subsidence coefficient, dimensionless.

(3) Calculation of working face inclination calculation length

In the formula, L is the calculated length of the inclination of the working face, unit: meter; D ₁ is the inclination length of the working face, unit: meter; S ₁ is the offset distance of the inflection point on the lower side of the working face, unit: meter; S ₂ is the upper side of the working face The inflection point offset distance, unit: meter; θ is the maximum subsidence angle, unit: degree; α is the coal seam inclination angle, unit: degree.

(4) Calculate the maximum subsidence value of the main section inclination

In the formula, W ^o _my is the maximum subsidence value of the main section, unit: mm; W ₀ is the maximum subsidence value of the ground surface when fully mining, unit: mm; r ₁ is the radius of influence in the downhill direction of the working face, unit: m ; r ₂ is the influence radius of the working face in the direction of the hill, unit: meter; y _m is the ordinate of the maximum subsidence point on the surface of the goaf center, unit: meter; L is the calculated length of the working face inclination, unit: meter.

Step 4. Calculating the coefficient of the working face's inclined mining degree

C _ym ＝W ^o _my /W ₀

In the formula, C _ym is the coefficient of inclined mining degree of the working face, dimensionless; W ^o _my is the maximum subsidence value of the inclined main section under insufficient mining, unit: mm; W ₀ is the maximum subsidence under full mining Value, unit: mm.

Step 5. Calculate the subsidence coefficient q' before activation

The maximum surface subsidence value W _m ′ obtained from the leveling survey of the surface trend line of the old mining area when new buildings are about to be built on the surface of the old mining area is obtained by the following formula to obtain q′:

q'=W _m '/(M×cosα)

In the formula, q′ is the subsidence coefficient before activation, dimensionless; W _m ′ is the maximum subsidence value of the surface of the old mining area when new buildings are about to be built on the surface of the old mining area, unit: mm; α is the coal seam inclination angle ;Unit: degree; M is mining thickness, unit: mm.

Step 6. Calculate the equivalent mining thickness m ₁ and the main influence radius r in the middle area of the working face

After activation of the uncompacted area and relatively fully compacted area in the middle of the old goaf, the limit subsidence coefficient is taken as ₁ , which is dimensionless; the equivalent mining thickness m1 and the main influence radius r of the middle area of the working face are calculated:

m ₁ =M(1-q')

In the formula, m1 is the equivalent mining thickness in the middle area _of the working face, unit: mm; M is the mining thickness, unit: mm; q′ is the subsidence coefficient before activation, dimensionless.

r=H ₀ /tanβ

In the formula, r is the main influence radius, unit: meter; H ₀ is the average mining depth, unit: meter; tanβ is the main influence angle tangent, dimensionless.

Step 7. Calculate the surface residual subsidence

In the formula, W _c (x) is the residual subsidence of the surface, unit: mm; x is the main cross-section in the direction of the basin, taking the surface point directly above the coal wall of the coal mining face as the origin, and taking the advancing direction of the coal face as Surface point coordinates in the axial direction, unit: meter; α is the coal seam inclination, unit: degree; M is the mining thickness, unit: mm; m ₁ is the equivalent mining thickness of the middle area of the working face, unit: mm; _Cym is the working face Inclination mining degree coefficient, dimensionless; r is the main influence radius, unit: m; S ₃ is the offset distance of the inflection point on the left side of the working face, unit: m; D ₃ is the length of the working face, unit: m; The calculated length l=D ₃ -S ₃ -S ₄ , unit: meter.

Step 8. Calculation of surface residual tilt deformation

In the formula, i _c (x) is the residual tilting deformation of the surface, unit: mm/m; x is the main cross section in the direction of the basin, taking the surface point directly above the coal wall of the coal mining face as the origin, and advancing with the coal face The direction is the coordinates of the surface point in the axial direction, unit: meter; α is the inclination angle of the coal seam, unit: degree; M is the mining thickness, unit: millimeter; r is the main influence radius, unit: meter; _Cym is the inclined mining degree of the working face Coefficient, dimensionless; constant e=2.718281828459; S ₃ is the offset distance of the inflection point on the left side of the working face, unit: m; m ₁ is the equivalent mining thickness of the middle area of the working face, unit: mm; D ₃ is the length of the working face, Unit: meter; the calculated length of the working face along the direction l=D ₃ -S ₃ -S ₄ , unit: meter.

Step 9. Calculate the surface residual curvature deformation

In the formula, k _c (x) is the residual curvature deformation of the surface, unit: 10 ^-3 /m; x is the main section in the direction of the basin, with the origin of the surface point directly above the coal wall of the cut hole in the coal mining face, and the coal mining The advancing direction of the surface is the coordinate of the surface point in the axial direction, unit: meter; _α is the inclination angle of the coal seam, unit: degree; M is the mining thickness, unit: mm; r is the main radius of influence, unit: meter; Mobility coefficient, dimensionless; constant e=2.718281828459; S ₃ is the offset distance of the inflection point on the left side of the working face, unit: m; m ₁ is the equivalent mining thickness of the middle area of the working face, unit: mm; D ₃ is the direction of the working face Length, unit: meter; length calculated along the working face l=D ₃ -S ₃ -S ₄ , unit: meter.

Step 10. Calculate the residual horizontal movement of the surface

U _c (x) = b ₁ ri _c (x)

In the formula, U _c (x) is the horizontal movement of the residual surface, unit: mm; x is the main cross section in the direction of the basin, with the origin of the surface point directly above the coal wall of the coal mining face, and the advancing direction of the coal face as Surface point coordinates in the axial direction, unit: meter; b ₁ is the horizontal movement coefficient; r is the main radius of influence, unit: meter; i _c (x) is the residual oblique deformation of the surface obtained in step 8, unit: mm/m .

Step 11. Calculate the residual horizontal deformation of the surface

ε _c (x) = b ₁ rk _c (x)

In the formula, ε _c (x) is the residual horizontal deformation of the surface, unit: mm/m; x is the main section in the direction of the basin, taking the surface point directly above the coal wall of the coal mining face as the origin, and advancing with the coal face The direction is the coordinates of the surface point in the axial direction, unit: meter; b ₁ is the horizontal movement coefficient, dimensionless; r is the main influence radius, unit: meter; k _c (x) is the residual curvature deformation of the surface, obtained by step 9, Unit: 10 ^-3 /m.

Step 12: Evaluate the damage level of new buildings on the surface of the old mining area

According to the residual surface deformation ε _c , surface residual curvature deformation K _c , and surface residual oblique deformation _ic to evaluate the damage grade of new buildings on the surface of old mining areas, the grades of ε _c , K _c , and _ic are compared with the national level in June 2000 Table 3 "Damage grades of brick-concrete structures" on pages 10 to 12 of the "Buildings, Water Bodies, Railways, and Main Shaft Coal Pillar Retention and Coal Mining Regulations" formulated by the Coal Industry Bureau is divided into Ⅰ～Ⅳ level.

Step 13. Select the prevention and control method for residual movement and deformation disasters

Based on the evaluation of the damage level of newly built buildings on the surface of the old mining area, the type of buildings and their anti-deformation requirements, a planning scheme for new anti-mining deformation buildings on the surface above the old goaf (building location planning and shape design measures) is proposed. ), building anti-mining deformation design scheme (rigid measures, flexible measures), foundation reinforcement scheme; in line with the principle of building safety first, after comprehensive analysis of the scheme and economic analysis, it is finally decided whether to Grouting treatment is applied to the boundary voids, central uncompacted areas, and overlying rock cracks in the underground old mining area with residual movement and deformation on the surface; after the grouting treatment, re-predict the residual movement and deformation of the surface and evaluate the anti-mining deformation according to the subsidence coefficient after treatment Architectural planning and design.

If the predicted value of the residual surface deformation after grouting treatment exceeds the building damage level I, the anti-mining deformation design scheme of the new building should be considered again, and even the drill holes should be drilled again for grouting treatment.

Step 14, the method of grouting implementation

Drill to the shallow old goaf, and use cement, sand, fly ash mixed slurry to fill all the cavities and overlying rock fissures in the goaf, so that the whole goaf can be restored to the state close to the original rock mass; for residential buildings, generally There can be one grouting hole per unit; the position and density of grouting should not be evenly distributed, and the drilling density of the building foundation should be strengthened.

⑴ Grouting material

In order to reduce the cost of treatment, grouting materials generally do not use mud, and 32.5# ordinary Portland cement and fly ash can be used; but the quality of cement meets the standards of Portland cement and ordinary Portland cement GB175-1999, and the quality of fly ash It is required to meet the national secondary standard; in order to ensure the strength of the filling body, the solid ratio of cement and fly ash is 1:3.

⑵ Serous ratio

The initial grouting is mainly thin grout to facilitate the spread of grout; after mastering the characteristics, gradually increase the grout concentration.

(3) For holes with large voids at the bottom or holes with suction phenomenon found in the drilling of reconnaissance holes or grouting holes, aggregate filling treatment should be carried out before grouting. Medium-grained sand is used for the aggregate, and it is fed into the bottom of the hole with clean water; if the cavity is too large, the filling effect of the cavity will not be obvious after filling the aggregate. Before formal grouting, it is necessary to set a grout stopper at a certain position at the bottom of the borehole to prevent the grout from being lost to the ground laneway.

⑷The construction process of goaf grouting engineering is generally divided into 14 processes, which are: preparation before construction → construction of grouting holes → establishment of grouting station → pressure test of grouting system → drilling flushing and pressure water test → Grouting and grouting→observation hole grouting process→observation and recording→pressurized water test after grouting→closing the grouting system→extracting the grouting plug→sealing the hole→EH4 geophysical detection to detect the grouting effect→supplementary grouting.

⑸When the grouting cannot be injected, the hole shall be sealed by pressing the cement mortar method.

The present invention explains in detail the prediction and prevention methods of the residual movement and deformation of the surface based on the existing rock movement parameters in various mining areas in my country; according to the evaluation of the three indicators of the damage level of new buildings on the surface of the old mining area, the surface inclination deformation i(x), the surface curvature The magnitude of the deformation K(x) and the horizontal surface deformation ε(x) can evaluate the damage level of new buildings on the surface of the old mining area; according to the damage level of the new buildings on the surface of the old mining area and the residual movement and deformation values of each surface, the new buildings on the surface can be analyzed The corresponding prevention and control measures should be taken; the prediction of surface residual movement and deformation provided by the invention has no new parameters, which solves the problem that the previous parameters are insufficient, new parameters such as Knothe parameter c appear, and the formula is difficult to popularize; the implementation of grouting is given. methods, including: grouting materials, grout ratio, technological process of goaf grouting engineering, etc.

Description of drawings

Accompanying drawing of the present invention altogether 1, accompanying drawing 1.

Fig. 1 is a schematic diagram of the length division of the working face and the coordinate system of residual movement and deformation under limited mining conditions.

Implementation

Embodiment. A certain mining area intends to build new buildings above the underground old mining area, and the old underground goaf is located below the corner point of the rectangular foundation of the new building on the surface.

The prediction and prevention methods of the residual movement and deformation of the ground surface caused by the new building are as follows:

Step 1. If the mining depth is greater than 150 meters, the new buildings on the surface of the old mining area will not cause the residual movement and deformation of the surface; if the mining depth is less than or equal to 150 meters, according to the criterion H _LJ published by Zhu Guangyi introduced in "Background Technology">H ₀ , calculate the critical depth of coal mining H _LJ ; compare the critical depth of coal mining H _LJ with the average mining depth H ₀ , if the criterion H _LJ >H ₀ is satisfied, it can be determined that there will be surface residual movement in the old mining area out of shape. In this example, the mining depth is less than or equal to 150 meters, and the calculated result H _LJ =Z+H _li +H _b =98.94 meters>H ₀ =79 meters according to the criterion. Therefore, under the influence of new buildings, there will be residual movement and deformation on the surface, and it is necessary to predict the residual movement and deformation of the surface. Continue with the following steps:

Step 2. Collect data in the following order:

⑴Collection of mining data: the mine map of the old underground mining area in the mining area is lost; go to the surface construction area of the old mining area for on-the-spot investigation, and visit the technical personnel related to the old mining area in geology, surveying, mining, etc., and the residents of the surface construction area; It is learned that the working face of the old mining area belongs to the mining during the Great Leap Forward.

The mining parameters are carried out by using the American EH-4 electrical conductivity imaging system (Electrical Conductivity Imaging System Hybrid-Source Magnetotellurics) to conduct geophysical prospecting through 5 observation lines (10 meters between measuring points and 17 meters between surveying lines) uniformly arranged in the geophysical prospecting area; Man-made misjudgment of EH-4 conductivity imaging, three geological boreholes were evenly distributed in the geophysical prospecting area as control holes for EH-4 conductivity imaging analysis, obtained: the strike length of the working face in the old mining area D ₃ = 500 meters, the inclination length D ₁ =100 meters, mining thickness M=3000 mm, coal seam inclination α=8 degrees, and average mining depth H ₀ =79 meters.

(2) Collect the rock movement parameters of the mining area: subsidence coefficient q=0.65, main influence angle tangent tanβ=1.2, horizontal movement coefficient b ₁ =0.20, inflection point offset S ₁ =S ₂ =S ₃ =S ₄ =10 meters, The maximum sinking angle θ=89 degrees.

(3) Leveling survey of the strike line of the surface of the old mining area when new buildings are about to be built on the surface of the old mining area, and W _m ′ = 2228 mm is obtained.

Step 3. Obtain the maximum subsidence value of the inclined main section in the following order

(1) Vertical coordinates of the maximum surface subsidence point in the center of the goaf

(2) Maximum surface subsidence when fully mined

W ₀ = Mqcosα = 3000 × 0.75 × cos8° = 2228 mm

(3) Calculation length of inclined working face

(4) The maximum surface subsidence value W ^o _my of the inclined main section

According to the above known conditions W ₀ =2228 mm, r ₁ =r ₂ =r=65.83 meters, y _m =39 meters, L=79.4 meters

Step 4. Calculating the coefficient of the working face's inclined mining degree

C _ym =W ^o _my /W ₀ =1937.2/[3000×0.75×cos(8°)]=0.8694.

Step 5. Calculate the subsidence coefficient q' before activation

Before new buildings are built on the surface of the old mining area, a leveling survey of the trend line of the surface of the old mining area is carried out, and the maximum surface subsidence value W _m '=2228 mm is obtained at this time, and the subsidence coefficient q'= W _m '/(M×cosα)=2228/[3000×cos(8°)]=0.75.

Step 6. Equivalent mining thickness m ₁ and main influence radius r in the middle area of the working face

m ₁ =M(1-q')=3000×(1-0.75)=750 (mm)

r=H ₀ /tanβ=79/1.2=65.83 (m)

Step 7. Calculate the surface residual subsidence W _c (x)

According to the above α = 8 degrees, M = 3000 mm, m ₁ = 750 (mm), C _ym = 0.8694, r = 65.83 (m), D ₃ = 500 m; the calculated length of the working face along the strike l = D ₃ -S ₃ -S ₄ ＝500-10-10＝480 (meters), S ₃ ＝S ₄ ＝10 (meters) is the offset distance of the inflection point on the left and right sides of the working face, for any point A(x) on the main cross section, From x=-1.5r=-1.5×65.83=-98.7 (meter), to x=D ₃ +1.5r=500+1.5×65.83=598.7 (meter), take the value of x according to the length interval of about 0.1r, such as taking At intervals of 5 meters, calculate the residual subsidence of the surface. For example, take a certain x=100 meters; bring into the surface residual subsidence W _c (x) formula:

Get, Wc (100) = 647 (mm)

Step 8. Calculate the surface residual tilt deformation i _c (x)

According to the above α = 8 degrees, M = 3000 mm, m ₁ = 750 (mm), C _ym = 0.8694, r = 65.83 (m), D ₃ = 500 meters, l = D ₃ -S ₃ -S ₄ =500 -10-10＝480 (meters), S ₃ ＝S ₄ ＝10 (meters), constant e＝2.718281828459, for any point A(x) on the main cross section, from x＝-1.5r＝-1.5×65.83＝- 98.7 (meters), until x=D ₃ +1.5r=500+1.5×65.83=598.7 (meters), take the value of x according to the length interval of about 0.1r, if the interval is 5 meters, calculate the residual oblique deformation of the surface. For example, take a certain x=100 meters, and bring it into the formula of surface residual tilt deformation _ic (x):

Get, ic(100)=0(mm/m)

Step 9. Calculate the surface residual curvature deformation

According to the above α = 8 degrees, M = 3000 mm, r = 65.83 meters, Cym = _0.8694 , S ₃ = S ₄ = 10 meters; m ₁ = 750 mm, D ₃ = 500 meters, l = D ₃ -S ₃ -S ₄ ＝500-10-10＝480 meters, constant e＝2.718281828459, for any point A(x) on the main section of the trend, from x＝-1.5r＝-1.5×65.83＝-98.7 (meter), to x＝ D ₃ +1.5r＝500+1.5×65.83＝598.7 (meters), take the value of x according to the length interval of about 0.1r, if the interval is 5 meters, calculate the residual curvature deformation of the surface. For example, take a certain x=100 meters and bring it into the surface residual curvature deformation k _c (x) formula:

Get, k _c (100)＝0.01(10 ^-3 /m)

Step 10. Calculate the residual horizontal movement of the surface

It is known that the horizontal movement coefficient b ₁ =0.2, r=H ₀ /tanβ=79/1.2=65.83 meters, ic(100)=0 mm/m, for any point A(x) on the main section, from x=-1.5 r=-1.5×65.83=-98.7 (m), to x=D ₃ +1.5r=500+1.5×65.83=598.7 (m), take the value of x according to the length interval of about 0.1r, if the interval is 5 meters, calculate Surface remnants move horizontally. For example, take a certain x=100 meters, and calculate the residual horizontal movement U _c (x) formula of the surface:

U _c (x) = b ₁ ri _c (x)

Get U _c (100)＝0.2×65.83×0＝0(mm)

Step 11. Calculate the residual horizontal deformation of the surface

It is known that the horizontal movement coefficient b ₁ =0.2, r=H ₀ /tanβ=79/1.2=65.83m, k _c (100)=0.01(10 ^-3 /m), for any point A(x) on the main cross section, From x=-1.5r=-1.5×65.83=-98.7 (meter), to x=D ₃ +1.5r=500+1.5×65.83=598.7 (meter), take the value of x according to the length interval of about 0.1r, such as taking At intervals of 5 m, calculate the residual horizontal deformation of the surface. For example, take a certain x=100 meters, and calculate the residual horizontal deformation of the surface ε _c (x) formula:

ε _c (x) = b ₁ rk _c (x)

Obtained, ε _c (100)=0.2×65.83×0.01=0.13 (mm/m).

Step 12. Evaluate the damage level of newly built buildings on the surface of the old mining area

According to the above steps 7 to 11, all the curves W _c (x), ic (x), k _c (x), U _c (x), ε _{c (} x) of the residual movement and deformation of the surface can be drawn. Taking the maximum value of each curve within the range of new buildings from the residual movement and deformation curve of the ground surface, we can get

W _cmax (x)＝712 mm; i _cmax (x)＝±13.2 mm/m; k _cmax (x)＝-0.44×10 ^-3 /m;

U _cmax (x) = ±175 mm; ε _cmax (x) = +4.5 mm/m.

According to the "Buildings, water bodies, railways, and main shaft coal pillars and coal mining regulations" formulated by the National Coal Industry Bureau in June 2000, p10-12: Table 3 "Damage grade of brick-concrete structures".

4mm/m< _εcmax <6.0mm/m;

0.4×10 ^-3 /m<k _cmax ＜0.6×10 ^-3 /m;

i _cmax >10.0 mm/m.

If no anti-deformation measures are taken, the damage level of newly built buildings will reach level IV, which is serious damage.

Step 13. Select the prevention and control method for residual movement and deformation disasters

Based on the evaluation of the damage level of new buildings on the surface of the old mining area, the type of buildings and their anti-deformation requirements, it is proposed that the new anti-mining deformation buildings on the surface above the old goaf should be built in situ, and qualified personnel should be hired before the construction of the buildings. The construction unit of the underground old mining area carries out grouting reinforcement treatment for the boundary cavity of the underground old mining area, the uncompacted area in the middle and the cracks in the overlying rock. Combined with the experience of grouting treatment in the old mining area under the same building in this area and the calculation and analysis results after grouting, there is no need to re-evaluate the calculation after grouting.

Step 14, the method of grouting implementation

Before building foundation construction, drill on the ground to the shallow old goaf, use cement, fly ash, sand and other mixed grout to fill and reinforce all the cavities and overlying rock fissures in the goaf, so that the entire goaf can be restored In order to be close to the state of the original rock mass, the underground space that causes the residual movement and deformation of the rock mass is eliminated. The drilling density is generally 35 meters. The location and density of grouting are not evenly distributed, and the drilling density of the foundation of the building must be strengthened. The opening diameter of the drilling hole is 130 mm, the diameter of the final hole is not less than 91 mm, and the diameter of the grouting pipe is 50 mm. During the drilling construction process, the inclination is measured every 35 meters, and the inclination of the final hole does not exceed 2 degrees.

⑴ Grouting material

In order to reduce treatment costs, 32.5# ordinary Portland cement and fly ash can be selected as grouting materials. However, the quality requirements of cement meet the standards of Portland cement and ordinary Portland cement GB175-1999, and the quality requirements of fly ash meet the national secondary standards. In order to ensure the strength of the filling body, the solid ratio of cement and fly ash is 1:3.

⑵ Serous ratio

The initial grouting is mainly thin grout to facilitate the spread of grout. After mastering the characteristics, gradually increase the slurry concentration.

(3) For holes with large voids at the bottom or holes with suction phenomenon found in the drilling of reconnaissance holes or grouting holes, aggregate filling treatment should be carried out before grouting. The aggregate is medium-grained sand, which is sent to the bottom of the hole with clean water.

If the cavity is too large, the filling effect of the cavity will not be obvious after filling the aggregate. Before formal grouting, a grout stopper should be installed at a certain position at the bottom of the borehole to prevent the grout from being lost to the underground roadway.

⑷The construction process of goaf grouting engineering is divided into 14 processes, which are: preparation before construction → construction of grouting holes → establishment of grouting station → pressure test of grouting system → drilling flushing and pressure water test → manufacturing Grouting→observation hole grouting process→observation and recording→pressurized water test after grouting→closing the grouting system→extracting the grouting plug→sealing the hole→EH4 geophysical detection to detect the grouting effect→supplementary grouting.

⑸When the hole cannot be injected after injection, the hole shall be sealed by pressing cement mortar to prevent the slurry from being squeezed out after construction.

Fig. 1. Schematic diagram of the length division of the working face and the residual moving deformation coordinate system under limited mining conditions, used in steps 7 to 11; wherein, D ₃ is the length of the working face; ι is the calculated length of the working face along the direction; S ₃ is the working face Left inflection point offset; S ₄ is the right inflection point offset of the working face; M is the mining thickness; H ₀ is the average mining depth; W _c (x) is the subsidence direction of the surface residual; ic (x) is the residual surface oblique deformation direction; Kc(x) is the direction of surface residual curvature deformation; Uc(x) is the direction of surface residual horizontal movement; εc(x) is the direction of surface residual horizontal deformation.

Claims (1)

1. A method for prediction and prevention of surface residual mobile deformation caused by newly built buildings in a mining area is characterized in that: its steps are: Step 1. If the mining depth of the working face in the old mining area is greater than 150 meters, the new buildings on the surface of the old mining area will not cause the residual movement and deformation of the surface; if the mining depth of the working face in the old mining area is less than or equal to 150 meters, calculate the critical depth of coal mining H _LJ , compare the coal mining critical depth H _LJ with the average mining depth H ₀ , if the criterion H _LJ >H ₀ is satisfied, it can be determined that there will be surface residual movement and deformation on the surface of the old mining area; continue with the following steps; Step 2. Collect data ⑴Collection of mining data: collect working face strike length D ₃ , working face inclination length D ₁ , mining thickness M, coal seam inclination α, average mining depth H ₀ , maximum subsidence angle θ through the mine map data of the mining area; to the old mining area On-the-spot investigation of the surface construction area; visits to the geological, surveying, mining professional technicians related to the old mining area, and residents of the surface construction area; Observation lines evenly laid out in the geophysical exploration area are obtained through analysis; the distance between observation line measuring points is 10 meters, and the distance between measurement lines depends on the accuracy of geophysical exploration, and can be 10 to 20 meters; in order to prevent human misjudgment of EH-4 conductivity imaging, More than two geological boreholes are evenly distributed as the control of the geophysical analysis of the EH-4 conductivity imaging system; (2) Collect rock movement parameters in the mining area: subsidence coefficient q, main influence angle tangent tanβ, horizontal movement coefficient b ₁ , inflection point offsets S ₁ , S ₂ , S ₃ on the lower, upper, left, and right sides of the working face , S ₄ , the maximum sinking angle θ; (3) When a new building is about to be built on the surface of the old mining area, a leveling survey of the trend line of the surface of the old mining area is carried out to obtain the maximum subsidence value W′ _m of the surface at this time; Step 3. Obtain the maximum subsidence value of the inclined main section in the following order (1) Calculate the ordinate of the maximum surface subsidence point in the center of the goaf ${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}$ In the formula, y _m is the ordinate of the maximum subsidence point on the surface of the goaf center, unit: meter; D ₁ is the inclination length of the working face, unit: meter; S ₁ is the offset distance of the inflection point on the lower side of the working face, unit: meter; θ is the maximum subsidence angle, unit: degree; α is the coal seam inclination angle, unit: degree; (2) Calculating the maximum surface subsidence value when fully mined W ₀ =Mqcosα In the formula, W ₀ is the maximum subsidence value of the surface during full mining, unit: mm; M is the mining thickness, unit: mm; α is the inclination angle of the coal seam, unit: degree; q is the subsidence coefficient, dimensionless; (3) Calculation of working face inclination calculation length $\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}$ In the formula, L is the calculated length of the inclination of the working face, unit: meter; D ₁ is the inclination length of the working face, unit: meter; S ₁ is the offset distance of the inflection point on the lower side of the working face, unit: meter; S ₂ is the upper side of the working face The inflection point offset distance, unit: meter; θ is the maximum subsidence angle, unit: degree; α is the coal seam inclination angle, unit: degree; (4) Calculate the maximum subsidence value of the main section inclination ${{\mathrm{<span\; class="notranslate">\; W</span>}}^{\mathrm{<span\; class="notranslate">\; o</span>}}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; \&lsqb;</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \}</span>$ In the formula, W ^o _my is the maximum subsidence value of the main section, unit: mm; W ₀ is the maximum subsidence value of the ground surface when fully mining, unit: mm; r ₁ is the radius of influence in the downhill direction of the working face, unit: m ; r ₂ is the influence radius of the working face in the direction of the hill, unit: meter; y _m is the ordinate of the maximum subsidence point on the surface of the goaf center, unit: meter; L is the calculated length of the working face inclination, unit: meter; Step 4. Calculating the mining degree coefficient of the working face tendency C _ym ＝W ^o _my /W ₀ In the formula, C _ym is the coefficient of inclined mining degree of the working face, dimensionless; W ^o _my is the maximum subsidence value of the inclined main section under insufficient mining, unit: mm; W ₀ is the maximum subsidence under full mining Value, unit: mm; Step 5. Calculate the subsidence coefficient q' before activation The maximum surface subsidence value W _m ′ obtained from the leveling survey of the surface trend line of the old mining area when new buildings are about to be built on the surface of the old mining area is obtained by the following formula to obtain q′: q'= _W'm /(M×cosα) In the formula, q' is the subsidence coefficient before activation, dimensionless; _W'm is the maximum subsidence value of the surface of the old mining area when new buildings are about to be built on the surface of the old mining area, unit: mm; α is the inclination angle of the coal seam ;Unit: degree; M is mining thickness, unit: mm; Step 6. Calculate the equivalent mining thickness m ₁ and the main influence radius r in the middle area of the working face After activation of the uncompacted area and relatively fully compacted area in the middle of the old goaf, the limit subsidence coefficient is taken as ₁ , which is dimensionless; the equivalent mining thickness m1 and the main influence radius r of the middle area of the working face are calculated: m ₁ =M(1-q') In the formula, m1 is the equivalent mining thickness in the middle area _of the working face, unit: mm; M is the mining thickness, unit: mm; q′ is the subsidence coefficient before activation, dimensionless; r=H ₀ /tanβ In the formula, r is the main influence radius, unit: meter; H0 is the average mining depth, unit: meter; _tanβ is the main influence angle tangent, dimensionless; Step 7. Calculate the surface residual subsidence ${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; MC</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>$ $<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; MC</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>$ In the formula, W _c (x) is the residual subsidence of the surface, unit: mm; x is the main cross-section in the direction of the basin, taking the surface point directly above the coal wall of the coal mining face as the origin, and taking the advancing direction of the coal face as Surface point coordinates in the axial direction, unit: meter; α is the coal seam inclination, unit: degree; M is the mining thickness, unit: mm; m ₁ is the equivalent mining thickness of the middle area of the working face, unit: mm; _Cym is the working face Inclination mining degree coefficient, dimensionless; r is the main influence radius, unit: m; S ₃ is the offset distance of the inflection point on the left side of the working face, unit: m; D ₃ is the length of the working face, unit: m; The calculated length l=D ₃ -S ₃ -S ₄ , unit: meter; Step 8. Calculation of surface residual tilt deformation $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; )</span>\end{array}$ In the formula, i _c (x) is the residual tilting deformation of the surface, unit: mm/m; x is the main cross section in the direction of the basin, taking the surface point directly above the coal wall of the coal mining face as the origin, and advancing with the coal face The direction is the coordinates of the surface point in the axial direction, unit: meter; α is the inclination angle of the coal seam, unit: degree; M is the mining thickness, unit: millimeter; r is the main influence radius, unit: meter; _Cym is the inclined mining degree of the working face Coefficient, dimensionless; constant e=2.718281828459; S ₃ is the offset distance of the inflection point on the left side of the working face, unit: m; m ₁ is the equivalent mining thickness of the middle area of the working face, unit: mm; D ₃ is the length of the working face, Unit: m; the calculated length of the working face along the direction l=D ₃ -S ₃ -S ₄ , unit: m; Step 9. Calculate the surface residual curvature deformation $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}\mathrm{<span\; class="notranslate">\; m</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; )</span>\end{array}$ In the formula, k _c (x) is the residual curvature deformation of the surface, unit: 10 ^-3 /m; x is the main section in the direction of the basin, with the origin of the surface point directly above the coal wall of the cut hole in the coal mining face, and the coal mining The advancing direction of the surface is the coordinate of the surface point in the axial direction, unit: meter; _α is the inclination angle of the coal seam, unit: degree; M is the mining thickness, unit: mm; r is the main radius of influence, unit: meter; Mobility coefficient, dimensionless; constant e=2.718281828459; S ₃ is the offset distance of the inflection point on the left side of the working face, unit: m; m ₁ is the equivalent mining thickness of the middle area of the working face, unit: mm; D ₃ is the direction of the working face Length, unit: meter; length calculated along the working face l=D ₃ -S ₃ -S ₄ , unit: meter; Step 10. Calculate the residual horizontal movement of the surface U _c (x) = b ₁ ri _c (x) In the formula, U _c (x) is the horizontal movement of the residual surface, unit: mm; x is the main cross section in the direction of the basin, with the origin of the surface point directly above the coal wall of the coal mining face, and the advancing direction of the coal face as The surface point coordinates in the axial direction, unit: meter; b ₁ is the horizontal movement coefficient; _r is the main radius of influence, unit: meter; ic (x) is the residual oblique deformation of the surface, obtained in step 8, unit: mm/ Meter; Step 11. Calculate the residual horizontal deformation of the surface ε _c (x) = b ₁ rk _c (x) In the formula, ε _c (x) is the residual horizontal deformation of the surface, unit: mm/m; x is the main section in the direction of the basin, taking the surface point directly above the coal wall of the coal mining face as the origin, and advancing with the coal face The direction is the coordinates of the surface point in the axial direction, unit: meter; b ₁ is the horizontal movement coefficient, dimensionless; r is the main influence radius, unit: meter; k _c (x) is the residual curvature deformation of the surface, obtained by step 9, Unit: 10 ^-3 /m; Step 12: Evaluate the damage level of new buildings on the surface of the old mining area According to the residual surface deformation ε _c , surface residual curvature deformation K _c , and surface residual oblique deformation _ic to evaluate the damage grade of new buildings on the surface of old mining areas, the grades of ε _c , K _c , and _ic are compared with the national level in June 2000 Table 3 "Damage grades of brick-concrete structures" on pages 10 to 12 of the "Buildings, Water Bodies, Railways, and Main Shaft Coal Pillar Retention and Coal Mining Regulations" formulated by the Coal Industry Bureau is divided into Grade Ⅰ～Ⅳ; Step 13. Select the prevention and control method for residual movement and deformation disasters Based on the evaluation of the damage level of newly built buildings on the surface of the old mining area, the type of buildings and their anti-deformation requirements, the planning scheme and the anti-mining deformation design of the buildings on the ground above the old goaf are proposed. plan and foundation reinforcement plan; in line with the principle of building safety first, after a comprehensive analysis of the plan and economic analysis, it is finally decided whether to remove the boundary cavity and the central part of the old underground mining area that has residual movement and deformation on the surface before the construction of the building. Grouting treatment is carried out in the area and overlying rock fissures; after the grouting treatment, re-predict the residual movement and deformation of the surface according to the subsidence coefficient after treatment, and evaluate the planning and design scheme of the anti-mining deformation building; If the predicted value of the residual surface deformation after grouting treatment exceeds the building damage level I again, the anti-mining deformation design scheme of the new building should be considered again, and even drill holes should be drilled again for grouting treatment; Step 14, the method of grouting implementation Drill to the shallow old goaf, and use cement, sand, fly ash mixed slurry to fill all the cavities and cracks in the overlying rock in the goaf, so that the whole goaf can be restored to the state close to the original rock mass; for residential buildings, it can be One unit, one grouting hole; the position and density of grouting should not be evenly distributed, and the drilling density of the building foundation should be strengthened; ⑴ Grouting material In order to reduce the cost of treatment, the grouting material does not use mud, and 32.5# ordinary Portland cement and fly ash can be used; but the quality requirements of cement meet the standards of Portland cement and ordinary Portland cement GB175-1999, and the quality requirements of fly ash It meets the national secondary standard; in order to ensure the strength of the filling body, the solid ratio of cement and fly ash is 1:3; ⑵ Serous ratio The initial grouting is mainly thin grout to facilitate the spread of grout; after mastering the characteristics, gradually increase the grout concentration; (3) For holes with large voids at the bottom or holes with suction phenomenon found in the drilling of reconnaissance holes or grouting holes, the aggregate should be filled before grouting; Send water into the bottom of the hole; if the cavity is too large, the filling effect of the cavity will not be obvious after filling the aggregate. Before formal grouting, it is necessary to install a grout stopper at a certain position at the bottom of the borehole to prevent the grout from being lost to the underground roadway; ⑷The construction process of goaf grouting engineering is divided into 14 processes, which are: preparation before construction → construction of grouting holes → establishment of grouting station → pressure test of grouting system → drilling flushing and pressure water test → manufacturing Grouting → observation hole grouting process → observation and recording → water pressure test after grouting → closing the grouting system → extracting the grouting plug → sealing the hole → EH4 geophysical detection of grouting effect → supplementary grouting; ⑸When the grouting cannot be injected, the hole shall be sealed by pressing the cement mortar method.