SU1739040A1 - Method for working contour compression relief - Google Patents

Abstract

This invention relates to the mining industry and underground construction. The purpose of the invention is to increase the stability of underground workings and the safety of tunnel works in rock massifs under conditions of dynamic manifestations of rock pressure, as well as a significant reduction in the cost of carrying out measures for unloading the marginal massif from stresses. The direction of maximum compressive stresses acting in an intact rock mass is determined. Then, the modulus of rocks of the surrounding array and the modulus of deformation of the material destroyed by the explosion are determined. On the section of the excavation contour with maximum stresses, they form an unloading slit of optimal depth determined by the formula lonm (B0 + 2 0.225 - KSH / EM + + D m, where B0 is the width of the mine working in the tunnel, m; A disturbed rocks, m; Ksch - modulus of deformation of the material filling the gap, MPa; Em - modulus of elasticity of rocks of the surrounding array, MPa. , 2 ill. LO С VI So about o fe

Description

The invention relates to the mining industry and underground construction and can be used during tunnel works in arrays composed of strong elastic rocks, in which, under the action of high stresses, dynamic manifestations of rock pressure are noted.

There is a known method of unloading mining from high horizontal compressive stresses. In accordance with this method, the stresses acting in the surrounding production are first measured. Then, using camouflage blasting in the walls of the mine workings create gaps. In this case, the slots are located in a plane parallel to the direction of the largest (in the described method, horizontal) stresses. The depth of the slots is chosen from the level of the existing

stresses and shock hazard categories of mine workings.

The disadvantage of this method is the need to build a slit of greater depth than if the slit is located perpendicular to the maximum compressive stresses in order to achieve an equal degree of discharge of the mine working contour. This leads to an increase in drilling, the consumption of explosive materials and the total cost of protective measures. In addition, the effect of changes in the parameters of drilling and blasting operations on the degree of rock loosening by camouflet blasting is not taken into account. All this will inevitably lead to uncertainty when choosing the parameters of the slit discharge. To determine unloading parameters, simulate unloading of production by solid unfilled crevices. At the same time, in practice, the slots which form camouflet blasting are used for unloading. After the explosion, the slots are filled with rock fractured by the explosion. This contradiction leads to errors in determining the required depth of the gap. Finally, a disadvantage of the method is the lack of consideration of the zone of disturbed rocks around the mine workings.

There is also known a method of unloading mine workings from high horizontal stresses, including the creation of unloading zones at the contact of the roof and the sides of the workings with a depth of 1-2 times the height of the workings. The discharge zones are supposed to be constructed by camouflage blasting.

The disadvantages of this method, like the previous one, include the relatively high costs of drilling and blasting work in the construction of the discharge zone, as well as the lack of consideration of the deformation characteristics of the exploded material-filling material of the discharge gap, which in practice may cause less stress reduction and excessive material costs. , as well as errors in determining the technological parameters of discharge generation.

Closest to the present invention is a method of unloading mine workings from compressive stresses. According to this method, the direction of the largest compressive stresses in the rock mass surrounding the mine working is first determined. Then, in the walls of the excavation, using camouflage blasting, gaps are created that are oriented perpendicular to the greatest compressive stress and intersect the excavation contour at a point with

maximum tangential compressive stresses. The depth of the slit is chosen depending on the width (height) of production or the size of the required protective zone.

The disadvantage of this method is the lack of consideration of the zone of disturbed rocks around the excavation, deformation properties of the marginal rock mass and

the influence of BVR parameters on the deformation characteristics of the loosened material filling the discharge gap. The method also does not provide the optimum for the factor of permissible stress level unloading of the mine working contour, which, in turn, adversely affects the stability of the production and safety of the tunnel works.

The aim of the invention is to improve the stability of mine workings and the safety of tunneling works while reducing the cost of protective shock-proof measures.

The goal is achieved by the fact that

determine the thickness of the marginal zone of disturbed rocks, the modulus of elasticity of the rocks of the surrounding array, and the modulus of deformation of the material filling the gap, and the discharge slot builds the optimum depth, determined by the formula

opt (Wo + 2 A) 0.225 - Ksch / Em + A m, where Ksch is the modulus of deformation of the material filling the gap, MPa;

Em - the modulus of elasticity of the rocks surrounding the array, MPa;

B0 - the width of the mine workings in the penetration, m;

L- power of the marginal zone of disturbed rocks, m (usually L 0.10-0.15 B0). Previously, when using slit unloading to determine its parameters, the thickness of the marginal zone of disturbed rocks was not taken into account. Also not taken into account

the influence of the ratio of the modulus of deformation of the material filling the gap to the modulus of elasticity of the rocks of the surrounding array to the optimal depth of the discharge zone of the slot.

Figure 1 shows the scheme of discharge horizontal generation; FIG. 2 shows plots obtained as a result of numerical simulation of slit mining

excavations that show the degree of discharge of the mine working contour near the point with maximum tangential stresses (t, A in Fig. 1) depending on the depth of the gap and the ratio of deformation properties of the material filling the gap and rocks of the marginal array.

Figure 2 indicates: a 1a is the concentration ratio of compressive stresses near t.A; a is the horizontal voltage 3 in Fig. 1; I - depth of the discharge gap, m; In-width mining in the sinking, m; 1, 2, 3 - graphs of change about ia depending on when Ksch / Em takes values of respectively 0.10; 0.01 and 0.00.

Example. A horizontal single excavation of 1 vaulted cross section with dimensions of 4 x 4 m of penetration is made. The penetration is carried out in strong elastic rocks, it is accompanied by dynamic manifestations of rock pressure (intensive firing and destruction of the roof of the excavation). In order to prevent disruption of production and increase work safety, a discharge gap 2 is used. To do this, the direction of maximum compressive stresses 3 is first determined (in this example, they are subhorizontal). The width of the zone of marginal disturbed rocks is determined 4. For single workings, this zone is A «{OI 0-0 ,. The gap is constructed by drilling and blasting. To do this, first determine the ratio of the modulus of deformation of loose rock that fills the discharge gap to the elastic modulus of the rocks of the marginal massif. This ratio depends on the technological parameters of drilling and blasting operations in the construction of the gap and on the properties of the rocks themselves. Next, the position on the contour of the point generation with maximum compressive tangential stresses is determined. In this example, this is T.A in FIG. 1, located at the top of the vault. The unloading slit is formed by camouflet blasting so that it intersects the working contour at this point. In this case, the distance between boreholes with a diameter of 42 mm is chosen to be 300 mm, they are charged with trained ammonite NS and LW and blown up. With this technology and these parameters, the ratio of the modulus of deformation of the loosened rock to the modulus of elasticity of the rocks of the marginal array will be approximately Ksch / Em «0.10. Further, in accordance with the proposed invention, the depth of the slit is optimal for this technology and these parameters of blistering.

wholesale - (Wo + 2 A) 0.225 - Ksch / Em + D (4.0 + 2 -0.6) 0.225-0, 6 1.25 m

(A "0.15-4, 6m)

On chart 1 (2) t. K corresponds to the optimal depth of the slit. The graph was obtained by modeling the discharge of output without taking into account the thickness of the zone of disturbed rocks (A 0). Indeed, equated to A 0, we get, 0 0,225-0, .5;

2 0 5 -40 0-25 a 1a 2.0. Next bur t

bore-holes with a depth of 1.25 m in accordance with

BVR passport so that they intersect the output contour in mA and are directed perpendicularly to voltage. If the load measures performed by this technology (camouflet blasting) with the given BVR parameters under the considered conditions did not lead to the required unloading effect contour development, it is advisable to either replace the technology or the parameters of the discharge measures. From the graphs in Fig. 2, it can be seen that a decrease in the KSch / EM ratio leads to an increase in the degree of unloading of the edge array. Consequently, if the application of the described measure did not eliminate the destruction of the excavation in a dynamic form, it is necessary to apply technology that ensures a lower value of the KSch / EM ratio. For example, use solid hollow slots for unloading the production contour. In this case, Ksch / Em 0.00. The slit is oriented, as shown in Fig. 1. Next, the optimum ratio for this ratio is determined in accordance with the invention.

KSH / Eat the depth of the gap

wholesale - (Vo +2 A) 0.225 - Ksch / Em + A (4.0 + 2 0.60) 0.225 - 0.00 + 0.60 1.77 m. Next, with the NKR-100 drilling machine, a well with a diameter of 105 is drilled mm in such a way that a solid floor gap is obtained, oriented as shown in FIG. The wells are drilled closely or even with overlapping cross sections. The gap thus formed allows

almost completely unload the production contour from high compressive stresses (see graph 3 in FIG. 2; with A-0, opt 0.9, 21 / B0 2 0.9 / 4.45, t. L, and ,20).

It should be noted that the proposed approach to determining the optimal depth of the gap depending on the Ksch / Em ratio is universal, i.e. does not depend on the technology of construction of the discharge gap.

If we use either a laser method, or fire drilling, or some other method, such as electrophysical, chemical, or mechanical methods, to construct the gap, the unloading parameters (optimal depth of the slot) will be uniquely determined by the ratio

Ksch / Em.

Thus, for each fixed Ksch / Em value, there exists its optimal slit depth (opt), at which the greatest discharge of the excavation contour is achieved near the most stressed point (e.g., fig 1).

The degree of discharge of the mine working contour is proportional to the value of 1 / (Ksch / Em) (cr a la Ksch / Em).

The more malleable the material filling the gap, the greater the depth of the gap is the greatest for a given Ksch / Em ratio, the discharge of the mine working contour (Ksch / Em).

Table 1 compares the technical and economic indicators of the proposed method of discharge generation with a known method. In both cases, the production of a 4 x 4 m section of the vaulted section is relieved. The efficiency of unloading measures is characterized by the ratio of la (the smaller the a / a, the more effective the measure of unloading).

The table shows that the proposed method is more effective for unloading the contour of the mine workings due to the fact that the compressive tangential stresses decrease by 1.5 times during its realization (near mA), and when the known method is used, these stresses decrease only 1 ,2 times. Increasing the discharge of the production contour has a positive effect on increasing the resilience of mine workings and the safety of tunneling. In addition, the application of the proposed method allows to significantly reduce the cost of carrying out unloading activities.

From the graph in figure 2 it can be seen that the wrong choice of the optimal depth of the discharge gap adversely affects

on unloading of the production contour: both a decrease in the depth of the gap and its increase, as compared to the optimum, will lead to an increase in dangerous concentrations of compressive stresses on the production contour near mA.

Claims (1)

Claim method The method of unloading the contour of the mine working from compressive stresses, including determining the direction of the maximum compressive stresses acting in the surrounding rock mass, the formation of the discharge gap, drilling and blasting, lying in a plane, perpendicular to the direction of maximum compressive stresses and intersecting the production contour at a point with maximum tangential compressive stresses, which, in order to improve the sustainability of the development and safety of tunneling works, as well as reduce the costs of protective measures, further determine the power the marginal zone of disturbed rocks and determine the modulus of elasticity of the rocks of the surrounding array and the deformation modulus of the material destroyed by the explosion, filling the gap, and the formation of the discharge gap is made to a depth determined by the formula opt (Wo + 2 A) 0.225 - KSH / EM + D m, where Bo is the width of the mine workings in the passageway, m; KSch — deformation modulus of the material filling the gap, MPa; Em is the modulus of elasticity of the rocks of the array surrounding the mining output, MPa; A-power of the marginal zone of disturbed rocks, m to 0 0.2 f 0.6 0.8 1.0 2l / 80 FIG. 2 Schig.1 Ku4 / Ј Vf ° L Ksch / Em 0,00 7