CN107060786A - A kind of Shield Construction Method Used method that groups of building are worn under karst region - Google Patents

Abstract

The invention discloses the technical field of urban subway tunnel construction, in particular to a shield tunneling construction method for passing through building groups in karst areas. The main construction steps of this method are: (a) building safety status investigation and monitoring system layout; (b) karst pre-detection and pretreatment; (c) shield tunneling test, to determine the construction parameters and dreg improvement process parameters; ( d) Formal excavation construction, and muck improvement, synchronous grouting and secondary reinforcement grouting; (e) Karst detection and treatment during shield excavation; (f) Karst detection and treatment behind the tunnel wall; (g) Exploration and treatment of caves in the first cave and karst caves in the latter cave. In this construction method, ground karst detection and pretreatment are carried out in the shield excavation section, muck improvement, synchronous grouting, and secondary reinforcement grouting are carried out during the shield excavation process, and the building section under the shield excavation is The tunnel is supplemented by measures such as karst exploration and treatment to ensure that the shield tunneling in the karst area passes smoothly under the building complex.

Description

A shield tunneling construction method for passing through building groups in karst areas

technical field

The invention relates to the technical field of urban tunnel construction, in particular to a shield tunneling construction method for passing through building groups in karst areas.

Background technique

With the continuous improvement of my country's economic level, a large number of rural populations are pouring into cities, which promotes urban development and also brings heavy traffic burdens to cities. Urban rail transit has developed rapidly due to its fast and non-occupied ground space. In the current track construction technology, the shield machine is usually used for tunnel excavation, and in the urban track construction in southern my country, it is often necessary to pass through the building complex in the karst area. In the current construction technology, the karst cave is usually grouted through ground drilling compaction to increase soil strength.

When the shield tunnel passes through the building, if there is no ground drilling construction conditions, it will not be possible to continue to use the above construction methods to detect and deal with karst. At the same time, due to the existence of buildings, the requirements for surface deformation are more stringent, urban rail construction will Faced with the dual challenges of karst detection and treatment and control of building deformation during shield tunneling.

Contents of the invention

The object of the present invention is to provide a shield tunneling construction method for tunneling under the building group in the karst area when the shield tunnel passes through the building group in the karst area and there is no ground drilling construction condition in some areas, and the building deformation requirements are strict. . The method detects and processes the karst area with the ground drilling construction face, and uses advanced drilling, geological radar scanning and tunnel drilling to detect the shield excavation area in the area where the ground drilling construction cannot be carried out. The development of karst in the interior, and the proven karst caves are reinforced by grouting through advanced drilling and tunnel drilling. At the same time, the deformation monitoring of the ground and buildings is strengthened during the construction process, and the monitoring information is fed back in time and the construction parameters are actively adjusted. , to ensure that the shield excavation of the tunnel passes smoothly through the building complex in the karst area.

In order to realize the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

A shield tunneling construction method for passing through building groups in a karst area, comprising the following steps:

a. Building safety status investigation and monitoring system layout;

b. Karst pre-detection and pre-treatment;

c. Shield tunneling test, to determine the construction parameters and dregs improvement process parameters;

d. Formal excavation construction, and muck improvement, synchronous grouting and secondary reinforcement grouting;

e. Karst detection and treatment during shield excavation;

f. Karst detection and treatment behind the tunnel wall;

g. Exploration and treatment of caves in advance and karst caves in subsequent caves.

In the above construction steps, the existing settlement and relative inclination of the building are measured by using a precision level and an indium steel ruler in the shield passing area, and its safety status and remaining structural deformation capacity are determined according to the type of building, so as to prepare for the subsequent karst reinforcement. Handling and tunnel shield underpassing provide safety basis.

The grouting reinforcement treatment of karst and the construction of tunnels using the shield method will inevitably have an impact on the surface environment along the line. In order to ensure project safety and protect the surrounding environment, it is necessary to monitor during the entire construction process, through the monitoring of settlement, relative inclination and cracks The system monitors the deformation of the building due to construction in real time, and according to the monitoring results, actively improves the construction process and construction parameters during the construction process to minimize the deformation of the surrounding ground and buildings.

In the above construction step b, the karst pretreatment range and karst development status must be identified before the karst area is pretreated. The scope of karst treatment must be based on the type of building, the shape and size of karst, and the relative positional relationship between karst and buildings to evaluate the impact of karst on buildings during shield tunneling, and then determine the scope of karst treatment.

In the above construction steps, the verification of the karst development status is to obtain core samples by using the vertical and inclined boreholes on the ground to determine the size and filling status of the karst caves.

In the tunnel shield excavation area where the ground vertical drilling cannot be carried out due to the existence of buildings, the multifunctional fast drilling rig of Mining Research Institute is used to conduct oblique drilling to detect karst caves, and the drilling plane position and angle are determined according to the buried depth of the tunnel and the position of the foundation of the house. .

For karst pretreatment, the corresponding reinforcement method must be selected according to the proven individual cave size and filling conditions, which can be summarized as follows:

(1) Full filling of caves: Sleeve valve tubes are used to perform layered compaction grouting on the fillings in the caves.

(2) Semi-filled and unfilled caves: sand blasting + chemical grouting.

(3) Grouting sequence: from the outside to the inside, first fill the boundary of the cave with double-liquid grout, block the leakage channel of the grout, and then gradually grout and compact the middle of the cave area with cement grout;

(4) In order to prevent grouting from adjacent holes and reduce the grouting effect, grouting must be performed by jumping holes.

When pretreating the cave, the grouting sequence must follow the principle from the outside to the inside, that is, first fill the cave boundary with double-liquid grout, block the leakage channel of the grout, and then gradually use the grouting grouting pressure in the middle of the cave area. At the same time, due to the large diffusion radius of the drilling grouting grout, the disturbance to the soil is large, and the grout solidification time is long, when the grouting reinforcement is carried out according to the drilling sequence, it is easy to cause grouting in adjacent holes and affect the reinforcement effect. It must be strengthened by jumping hole grouting.

In the karst pretreatment reinforcement, the periphery of the grouting reinforcement area can be closed with double-liquid slurry to prevent the leakage of the grout, and the interior is filled with pure cement slurry; the material of the double-liquid slurry is cement slurry and water glass solution, and the cement slurry components include cement and Water, the water-cement ratio is 0.5:1~1:1, the water glass solution includes water glass and water, the concentration of the water glass solution is 30~40°Be', and the ratio of cement slurry and water glass solution is 4:1~6:1 ; The components of pure cement slurry include cement and water, and the water-cement ratio is 0.5:1 to 1:1. The specific mixing ratio should be determined according to field tests.

In the karst pretreatment reinforcement, for the periphery of the reinforcement area, in order to make the grout solidify quickly and effectively prevent the grout from leaking, the grouting should be controlled with a relatively small pressure, multiple times, and relatively large quantities. The grouting pressure is 0.4-0.7 MPa, and the grouting frequency is 3-3 4 times; for the middle part of the reinforcement area, the grouting pressure is 0-0.7MPa, and the grouting pressure is gradually increased from 0 to the final grouting pressure, and the grouting is continued for more than 10 minutes, the grouting is 3 times, and the grouting speed is 30-50L/min ; The intermittent time of each grouting is 30 minutes for the periphery of the reinforcement area, and 6-10 hours for the middle of the reinforcement area. Intermittent grouting is used to fill the extruded soil multiple times, so that the strength of the soil can be maximized and the soil can be effectively reduced. permeability coefficient.

In the above construction steps, after the karst pretreatment, the grouting effect must be inspected. The inspection method is the drilling core-pulling method combined with the random in-situ standard penetration test. The number of inspections is 1% of the number of grouting holes, and each The number of inspections shall not be less than one inspection drill hole. The soil in the grouting reinforcement area should meet the 28d unconfined compressive strength value of the borehole core sample ≥ 0.5MPa; the permeability coefficient of the reinforcement body should not be greater than 1×10 ^-5 cm/s; The speed is not less than 10 hits.

Before the formal excavation of the shield tunneling in the karst area, the construction parameters should be determined according to the trial excavation. The construction parameters include total thrust, advancing speed, cutter head torque, soil chamber pressure and synchronous grouting parameters. Among them: the total thrust is 1300-1600t, the propulsion speed is 5-10mm/min, the cutterhead torque is 3.0-3.5MN·m, the soil bin pressure is 1.2-1.4Bar, the synchronous grouting rate is 300%, the synchronous grouting pressure Between 2.0 and 4.0 Bar. During the formal tunneling process of the shield machine, the construction parameters should be adjusted according to the real-time settlement and deformation monitoring data of the building and the properties of the soil in front of the shield machine.

In the above construction steps, in order to prevent the clogging of the cutter head dregs improvement nozzle, and at the same time lubricate and cool the cutter head cutter, a foam agent should be used for dregs improvement, wherein the concentration of the foam stock solution is 3 to 5%, and the foaming rate is 10% ~20 times, the injection rate is 5~10%. The parameters of the muck improvement process must be adjusted according to real-time working conditions.

In the above construction steps, the synchronous grouting slurry is selected from double-liquid slurry, and the material of the double-liquid slurry is cement slurry and water glass solution, wherein the cement slurry is composed of cement and water, and the water-cement ratio is 1:1; the water Glass solution composition is water glass and water, and water glass concentration is 30～40 ° Be ', and its volume mixing ratio is water glass: water=1:1～1:2; Described cement slurry and water glass solution volume mixing ratio are 4:1 to 6:1; the grout ratio should be determined on the basis of the current ratio through on-site trial matching, and adjusted and optimized according to the on-site excavation conditions.

In the above construction steps, after the shield machine passes through, a geological radar survey line should be arranged longitudinally in the forming tunnel to scan the cavity behind the segment wall, and a second double-liquid slurry reinforcement injection should be immediately organized for the positions where looseness, cavity, and looseness are abnormal. slurry to achieve the purpose of reinforcing the soil and reinforcing the filling cavity.

The secondary reinforcing grouting grout is double-fluid grout, and the material of the double-fluid grout is cement slurry and water glass solution, wherein, the cement slurry components are cement and water, and the water-cement ratio is 1:1; the water glass solution The composition is water glass and water, the concentration of water glass is 30～40°Be', its volume mixing ratio is water glass: water=1:1～1:2; the volume mixing ratio of described cement slurry and water glass solution is 4: 1～6:1.

In the above-mentioned construction steps, in the areas where ground drilling cannot be carried out, the advanced drilling facilities at the front end of the shield machine should be used to find out the karst development in the direction of tunnel excavation, and the geological radar scanning and drilling in the tunnel should be used to find out the formed tunnel segment wall After the karst caves, the proven karst caves were grouted and reinforced through intensified drilling. The scope of karst treatment must be obtained by evaluating the impact of karst on buildings during shield excavation based on building type, karst shape and size, and relative positional relationship between karst and buildings.

The karst treatment in the shield excavation process is to use the advanced drilling equipment and the boreholes in the tunnel to grout the tunnel excavation direction and the proven karst caves around the formed tunnel. The grouting reinforcement methods can be summarized as follows:

(1) In order to ensure the safety of the building, for the proven karst that needs to be dealt with, regardless of the size of the cave and the filling condition, it is reinforced with double liquid slurry;

(2) Grouting sequence: from outside to inside, first fill the boundary of the cave with double-liquid grout, block the leakage channel of the grout, and then gradually grout and compact the middle of the cave area inward;

(3) In order to prevent grouting in adjacent holes from affecting the grouting effect, grouting must be carried out by skipping holes.

Both advanced drilling and tunnel drilling and grouting reinforcement are double-fluid slurry, and the double-fluid slurry material is cement slurry and water glass solution. Including water glass and water, the concentration of water glass solution is 30-40°Be', and the ratio of cement slurry and water glass solution is 4:1-6:1.

For the grouting around the karst reinforcement area, the grouting pressure is 0.4-0.7MPa, the grouting time is 3-4 times, and the interval between each grouting is 30 minutes; for the middle part of the reinforcement area, grouting The grouting pressure can be 0~0.4MPa, reach the final grouting pressure and continue grouting for more than 10min, grouting 4~5 times, the grouting speed is 20~30L/min, and the interval time of each grouting is 30min.

In the section under the building where the ground drilling detection cannot be implemented, the geological situation of the unconstructed section of the other tunnel is proved by adding the geological radar survey line in the corresponding range of the tunnel ahead and supplemented by drilling in the tunnel. If it is found that there is a karst cave in the corresponding area of the other tunnel, the tunnel segment of the constructed side can be intensified and drilled for grouting.

In the above construction steps, when performing grouting reinforcement treatment on the karst in the area where the tunnel passes under the building on the other side, the grout adopts double-fluid grout, and the double-fluid grout material is cement slurry and water glass solution, wherein the cement grout is composed of cement and water, the water-cement ratio is 1:1; the composition of water glass solution is water glass and water, the concentration of water glass is 30-40°Be', and its volume mixing ratio is water glass: water = 1:1-1:2; The volume ratio of the cement slurry to the water glass solution is 4:1-6:1.

When performing grouting reinforcement treatment on the karst in the area where the tunnel passes under the building on the other side, for the peripheral grouting of the karst reinforcement area, the grouting pressure should be controlled at a relatively small pressure, multiple times, and a relatively large amount. ~ 4 times, the intermittent time of each grouting can be 30min; for the middle part of the reinforcement area, the grouting pressure can be 0-0.4MPa, reach the final grouting pressure and continue grouting for more than 10min, grouting 4-5 times, the grouting speed is 20 ~30L/min, the interval time between each grouting is 30min.

Description of drawings

Fig. 1 is the flow chart of the construction method of shield tunneling under the building complex in the karst area of the present invention.

Figure 2 is a schematic diagram of the detection of karst caves by oblique holes on the ground.

Fig. 3 is a schematic diagram of the section of the karst cave detected by advanced drilling in the tunnel.

Figure 4 is a schematic diagram of geological radar and borehole detection of karst caves in the tunnel.

Fig. 5 is a schematic diagram of the karst cave after the first cave exploration.

Marks in the figure: 1—building, 2—ground surface, 3—ground inclined hole detection, 4—karst cave, 5—planned tunnel, 6—advanced drilling detection, 7—completed tunnel, 8—shield machine, 9— Borehole detection in the tunnel, 10—Georadar detection, 11—Drill hole detection in the first cave, and then the karst cave.

detailed description

The present invention will be further described in detail below in conjunction with test examples and specific embodiments. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

Example

This embodiment is used in the construction occasion of shield tunneling under the building group in the karst area.

As shown in Figure 1, the shield tunneling construction method for passing through the building complex in the karst area includes the following steps:

a. Building safety status investigation and monitoring system layout;

b. Karst pre-detection and pre-treatment;

c. Shield tunneling test, to determine the construction parameters and dregs improvement process parameters;

d. Formal excavation construction, and muck improvement, synchronous grouting and secondary reinforcement grouting;

e. Karst detection and treatment during shield excavation;

f. Karst detection and treatment behind the tunnel wall;

g. Exploration and treatment of caves in advance and karst caves in subsequent caves.

In the above construction steps, the existing settlement and relative inclination of the building are measured by using a precision level and an indium steel ruler in the building area of the shield tunneling area, and its safety status and remaining structural deformation capacity are determined according to the type of building. It provides a safety basis for subsequent karst reinforcement treatment and tunnel shield tunneling.

By laying out settlement, relative inclination and crack monitoring systems, real-time monitoring of the deformation of buildings due to construction, and according to the monitoring results, during the construction process, the construction process and construction parameters are actively improved to minimize the surrounding surface, buildings, etc. deformation.

In the above-mentioned construction steps, within the scope of karst treatment, the core samples were obtained by using the vertical drilling and inclined drilling on the ground to determine the size and filling of the cave, so as to provide a basis for subsequent karst treatment.

The scope of karst treatment must be obtained by evaluating the impact of karst on buildings during shield excavation based on building type, karst shape and size, and relative positional relationship between karst and buildings.

As shown in Figure 2, when there is no vertical drilling face on the ground, the mining research multifunctional fast drilling rig can be used to detect and process karst caves by oblique drilling, and the plane position and angle of the drilling can be determined according to the buried depth of the tunnel and the position of the foundation of the house.

In the above construction steps, according to the cave size and filling conditions, the karst treatment methods can be summarized as follows:

(1) Full filling of caves: Sleeve valve tubes are used to perform layered compaction grouting on the fillings in the caves.

(2) Semi-filled and unfilled caves: sand blasting + chemical grouting.

(3) Grouting sequence: from the outside to the inside, first fill the boundary of the cave with double-liquid grout, block the leakage channel of the grout, and then gradually grout and compact the middle of the cave area with cement grout;

(4) In order to prevent grouting from adjacent holes and reduce the grouting effect, grouting must be performed by jumping holes.

In order to make the grout gradually squeeze the filling soil, thereby maximizing the strength of the soil, reducing the permeability coefficient of the soil, and providing guarantee for the subsequent shield tunneling construction, when pretreatment and grouting reinforcement of the cave, the grouting sequence is from outward to Based on the internal principle, first fill the boundary of the cave with double-fluid grout to block the passage of grout leakage, and then gradually use cement slurry inward to compact the grouting in the middle of the cave area; The disturbance of the body is large, and the solidification time of the grout is long. When the grouting reinforcement is carried out according to the drilling sequence, it is easy to cause the grouting in the adjacent holes and affect the reinforcement effect, so the grouting reinforcement must be skipped.

In the karst pretreatment reinforcement, the periphery of the grouting reinforcement area can be closed with double-liquid slurry to prevent the leakage of the grout, and the interior is filled with pure cement slurry; the material of the double-liquid slurry is cement slurry and water glass solution, and the cement slurry components include cement and Water, the water-cement ratio is 0.5:1~1:1, the water glass solution includes water glass and water, the concentration of the water glass solution is 30~40°Be', and the ratio of cement slurry and water glass solution is 4:1~6:1 ; The components of pure cement slurry include cement and water, and the water-cement ratio is 0.5:1 to 1:1. The specific mixing ratio should be determined according to field tests.

In the karst pretreatment reinforcement, for the periphery of the reinforcement area, in order to make the grout solidify quickly and effectively prevent the grout from leaking, the grouting should be controlled with a relatively small pressure, multiple times, and relatively large quantities. The grouting pressure is 0.4-0.7 MPa, and the grouting frequency is 3-3 4 times; for the middle part of the reinforcement area, the grouting pressure is 0-0.7MPa, and the grouting pressure is gradually increased from 0 to the final grouting pressure, and the grouting is continued for more than 10 minutes, the grouting is 3 times, and the grouting speed is 30-50L/min ; The intermittent time of each grouting is 30 minutes for the periphery of the reinforcement area, and 6-10 hours for the middle of the reinforcement area. Intermittent grouting is used to fill the extruded soil multiple times, so that the strength of the soil can be maximized and the soil can be effectively reduced. permeability coefficient.

In the above construction steps, after the karst pretreatment, the grouting effect must be inspected. The inspection method is the drilling core-pulling method combined with the random in-situ standard penetration test. The number of inspections is 1% of the number of grouting holes, and each The number of inspections shall not be less than one inspection drill hole. The soil in the grouting reinforcement area should meet the 28d unconfined compressive strength value of the borehole core sample ≥ 0.5MPa; the permeability coefficient of the reinforcement body should not be greater than 1×10 ^-5 cm/s; The speed is not less than 10 hits.

Before the formal excavation of the shield tunneling in the karst area, the construction parameters should be determined according to the trial excavation. The construction parameters include total thrust, advancing speed, cutter head torque, soil chamber pressure and synchronous grouting parameters. Among them: the total thrust is 1300-1600t, the propulsion speed is 5-10mm/min, the cutterhead torque is 3.0-3.5MN·m, the soil bin pressure is 1.2-1.4Bar, the synchronous grouting rate is 300%, the synchronous grouting pressure Between 2.0 and 4.0 Bar. During the formal tunneling process of the shield machine, the construction parameters should be adjusted according to the real-time settlement and deformation monitoring data of the building and the properties of the soil in front of the shield machine.

In order to prevent clogging of the cutterhead dregs improvement nozzle, and at the same time lubricate and cool down the cutterhead cutter, a foam agent should be used for dregs improvement. The concentration of the foam stock solution is 3-5%, and the foaming rate is 10-20 times. The rate is 5-10%. The parameters of the muck improvement process must be adjusted according to the real-time working conditions.

In the above-mentioned construction steps, the synchronous grouting slurry is selected from double-liquid slurry, and the material of the double-liquid slurry is cement slurry and water glass solution, wherein the water-cement ratio of the cement slurry is 1:1; the composition of the water glass solution is water glass And water, water glass concentration is 30～40 ° Be ', and its volume mixing ratio is water glass: water=1:1～1:2; Described cement slurry and water glass solution volume mixing ratio are 4:1～6: 1. The grout ratio should be determined on the basis of the current ratio, and be adjusted and optimized according to the on-site excavation conditions.

In the above construction steps, after the shield machine passes through, the survey line should be arranged longitudinally in the forming tunnel, the cavity behind the segment wall should be scanned by geological radar, and the second double-fluid slurry repair should be organized immediately for the loose, cavity and loose abnormal positions. Strong grouting to achieve the purpose of reinforcing the soil and filling the void.

The secondary reinforcing grouting grout is double-fluid grout, and the material of the double-fluid grout is cement slurry and water glass solution, wherein, the cement slurry components are cement and water, and the water-cement ratio is 1:1; the water glass solution The composition is water glass and water, the concentration of water glass is 30～40°Be', its volume mixing ratio is water glass: water=1:1～1:2; the volume mixing ratio of described cement slurry and water glass solution is 4: 1～6:1.

As shown in Figure 3 and Figure 4, the karst detection of the section under the building is to use advanced drilling in the area where ground drilling cannot be implemented, and the geological radar scanning in the formed tunnel hole is supplemented by drilling in the tunnel to prove the front of the tunnel. and surrounding karst development. The advanced drilling is to use the advanced drilling equipment arranged in front of the shield machine to find out the karst development situation in front of the tunnel when the shield machine is shut down to install the segments. Drilling with a certain included angle; the geological radar scanning is supplemented by tunnel drilling, that is, the karst development status behind the wall of the segment is detected by transmitting and receiving electromagnetic waves in the formed tunnel hole, and the karst around the tunnel is further confirmed by drilling in the tunnel developmental status.

In the above-mentioned construction steps, the karst treatment of the underpassing building section is to use the advanced drilling equipment and the boreholes in the tunnel to perform grouting reinforcement treatment on the tunneling direction and the proven karst around the formed tunnel. Among them, the advanced drilling equipment can be used for karst treatment in front of the tunnel, and the drilling in the tunnel can be used for karst treatment behind the segment wall. The grouting reinforcement methods can be summarized as follows:

(1) In order to ensure the safety of the building, regardless of the size of the cave and the filling condition, it is reinforced with double liquid slurry;

(2) Grouting sequence: from outside to inside, first fill the boundary of the cave with double-liquid grout, block the leakage channel of the grout, and then gradually grout and compact the middle of the cave area inward;

(3) In order to prevent grouting in adjacent holes from affecting the grouting effect, grouting must be carried out by skipping holes.

The karst grouting reinforcement in the building section below is a double-liquid slurry, and the double-liquid slurry material is cement slurry and water glass solution. The cement slurry includes cement and water. The composition of glass solution includes water glass and water, the concentration of water glass solution is 30-40°Be', the ratio of cement slurry and water glass solution is 4:1-6:1; the composition of pure cement slurry includes cement and water, and the water-cement ratio is 0.5:1～1:1.

Under the building section, grouting around the karst reinforcement area should be controlled with relatively small pressure, multiple times, and relatively large quantities. The grouting pressure is 0.4-0.7MPa, and the grouting is 3-4 times. The interval between each grouting is preferably 30 minutes; For the middle part of the reinforcement area, the grouting pressure can be 0-0.4MPa, reach the final grouting pressure and continue grouting for more than 10 minutes, grouting 4-5 times, the grouting speed is 20-30L/min, and the interval time of each grouting is taken as 30min.

As shown in Figure 5, in the underpass building section where the ground drilling detection cannot be implemented, the geological radar survey line is added in the corresponding range of the leading tunnel tunnel, and the geological conditions of the unconstructed section of the other tunnel are scanned and processed. If it is found that there is a karst cave in the underpass area of another tunnel, the karst cave can be grouted from the intensified drilling of the tunnel on the side that has already been constructed. set up.

In the above construction steps, when performing grouting reinforcement treatment on the karst in the area where the tunnel passes under the building on the other side, the grout adopts double-fluid grout, and the double-fluid grout material is cement slurry and water glass solution, wherein the cement grout is composed of cement and water, the water-cement ratio is 1:1; the composition of water glass solution is water glass and water, the concentration of water glass is 30-40°Be', and its volume mixing ratio is water glass: water = 1:1-1:2; The volume ratio of the cement slurry to the water glass solution is 4:1-6:1.

When performing grouting reinforcement treatment on the karst in the area where the tunnel passes under the building on the other side, for the peripheral grouting of the karst reinforcement area, the grouting pressure should be controlled at a relatively small pressure, multiple times, and a relatively large amount. ~ 4 times, the intermittent time of each grouting can be 30min; for the middle part of the reinforcement area, the grouting pressure can be 0-0.4MPa, reach the final grouting pressure and continue grouting for more than 10min, grouting 4-5 times, the grouting speed is 20 ~30L/min, the interval time between each grouting is 30min.

In this embodiment, through the investigation and evaluation of the safety status of buildings in karst areas and the preset settlement, relative inclination and crack monitoring system, the law of the impact of construction on buildings is identified, and the construction is guided by feedback monitoring information; The pre-detection of the area is carried out, and the proven karst caves are treated with grouting reinforcement in different ways, and the advanced drilling, geological radar scanning and borehole technology in the formed tunnel are used to detect the development of karst under the building without ground drilling. In this way, the karst caves around the tunnel are densely drilled for grouting reinforcement, and the karst caves around the tunnel are drilled from the first hole to prove and deal with the karst caves around the tunnel; the grouting reinforcement of the proven karst caves can increase the strength of the soil and reduce the soil strength. The body permeability coefficient ensures that the shield excavation construction smoothly passes through the building complex in the karst area.

Claims (10)

1. a kind of Shield Construction Method Used method that groups of building are worn under karst region, it is characterised in that comprise the following steps：

A, investigation building safety present situation, lay monitoring system；

B, karst pre-detection and pretreatment；

C, shield sondage are entered, and determine construction parameter and sediment improvement technological parameter；

D, formal tunneling construction, and give sediment improvement, synchronous grouting and secondary reinforcement slip casting；

Karst and processing in e, shield tunneling process；

Karst and processing after f, tunnel wall；

Row hole solution cavity after g, leading exploratory tunnel excavating are looked into and handled.

2. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 1, it is characterised in that in step In a, using precision level, indium steel ruler carries out settlement observation and inclination measurement to building, and is obtained according to building type Its security status and remaining structure deformability；The monitoring system includes Building's Subsidence Survey, relative tilt monitoring and split Seam monitoring, realizes that settlement monitoring and relative tilt are monitored by close spirit level and indium steel ruler, complete by metal bar and slide measure Into Crack Monitoring；Strengthen monitoring in whole work progress and feedback monitoring information is with guiding construction.

3. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 1, it is characterised in that in step In b, the karst pre-detection is visited in the location with bore detecting working face by way of vertical drilling or inclined drill Bright karst treatment scope and karsts developing area situation；The karsts developing area situation includes karst size and filling situation；The karst Process range assesses shield driving according to building type, Karst Features and size, karst and building relative position relation Process of Karst determines karst treatment scope to effect on building；

The karst pretreatment is that basis has verified single solution cavity size and filling situation selects corresponding reinforcement means, the solution cavity For full-filling solution cavity, partly fill or be not filled by solution cavity；The reinforcement means of solution cavity is grouting and reinforcing processing method, specific as follows：

For full-filling solution cavity：Layering compaction grouting is carried out to charges in solution cavity using mini-valve tube；

For partly filling and being not filled by solution cavity：Using the method for blast+chemical grouting；

Grouting sequence is as follows：Ecto-entad is carried out, and is first given solution cavity border dual slurry filling, is blocked after slurries leakage channel, Again progressively inwardly with cement mortar to grouting densification in the middle part of solution cavity area；

Wherein, to prevent adjacent hole grout leaking reduction slip casting effect, slip casting must jump hole progress；

After karst has been pre-processed, slip casting effect is tested, the method for inspection is that the random mark in situ of drilled drawing-core method combination passes through examination Test, amount detection is the 1% of slip casting hole number, and each solution cavity amount detection detects drilling no less than 1.

4. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 1, it is characterised in that in step In c, enter to determine construction parameter according to shield sondage；The construction parameter includes gross thrust：1300~1600t, fltting speed：5 ~10mm/min, cutter head torque：3.0~3.5MNm, support pressure：1.2~1.4Bar, synchronous grouting rate is 300%, synchronous Grouting pressure：2.0~4.0Bar；

Enter to determine the technological parameter of foaming agent sediment improvement by shield sondage, wherein, foam dope concentration is 3~5%, foaming Rate is 10~20 times, and injection rate is 5~10%.

5. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 1, it is characterised in that in step In d, secondary grouting is constructed i.e. after shield machine gives section of jurisdiction wall after for the secondary reinforcement slip casting, is reached soil mass consolidation and is added Gu fill the purpose in cavity；

The synchronous grouting and secondary reinforcement grouting serous fluid are cement+waterglass dual slurry, wherein, the cement mortar ratio of mud is 1: 1, water glass solution composition is waterglass and water, and concentration of sodium silicate is 30~40 ° of Be ＇, and its nominal mix proportion is waterglass：Water= 1:1~1:2；Cement mortar and the water glass solution nominal mix proportion is 4:1~6:1；Grout coordinate ratio should be existing with proportioning basis It is upper to carry out live trial determination, and adjusted and optimized according to live driving condition.

6. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 1, it is characterised in that in step In e, Karst and processing can not implement surface drilling detection location in the shield tunneling process, before shield machine End advance drilling facility verifies karsts developing area situation in tunnel piercing direction, and solution cavity is given at grouting and reinforcing by encrypting drilling Reason.

7. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 1, it is characterised in that in step In f, Karst and processing are to molded by way of geological radar scanning is aided with tunnel internal drilling after the tunnel wall The soil body carries out Karst after tunnel duct piece wall, and carries out grouting and reinforcing processing to having verified solution cavity encryption drilling, wherein drilling And slip casting is reserved aperture by section of jurisdiction and carried out.

8. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 1, it is characterised in that in step In g, after the leading exploratory tunnel excavating is looked into and handled row hole solution cavity i.e. can not implement surface drilling detection location pass through in leading hole tunnel Road respective range verifies the non-construction section geological condition in another tunnel by way of geological radar scanning is aided with tunnel internal drilling And give grouting and reinforcing processing.

9. wearing the Shield Construction Method Used method of groups of building under karst region according to claim 6,7 or 8 are any, its feature exists In the method for the grouting and reinforcing processing method is as follows：

(1) to ensure building safety, solution cavity must be handled to having verified, no matter its size is entered with filling situation using dual slurry Row grouting and reinforcing；

(2) grouting sequence：Ecto-entad is carried out, and is first given solution cavity border dual slurry filling, is blocked after slurries leakage channel, then Progressively inwardly to grouting densification in the middle part of solution cavity area；

(3) to prevent adjacent hole grout leaking influence slip casting effect, slip casting must jump hole progress.

10. the Shield Construction Method Used method of groups of building is worn under karst region according to claim 9, it is characterised in that described The slurry material that grouting and reinforcing processing is used includes dual slurry and neat slurry；The dual slurry slurry material is that cement mortar and waterglass are molten Liquid, wherein the cement mortar ratio of mud are 0.5:1~1:1, water glass solution composition includes waterglass and water, and water glass solution concentration is 30~40 ° of Be ＇, cement mortar and water glass solution match ratio are 4:1~6:1；The neat slurry composition ratio of mud is 0.5:1~1:1；

Wherein, for the peripheral slip casting in stabilization zone, 0.4~0.7MPa of grouting pressure, slip casting 3~4 times, each slip casting intermittent time can Take 30min；For in the middle part of stabilization zone, in general shield driving section, grouting pressure is 0~0.7MPa, reach final grouting pressure and after Continuous more than slip casting 10min, mud jacking 3 times, 30~50L/min of injection speed, each slip casting intermittent time takes 6~10h, wears and build under Build thing section grouting pressure and take 0~0.4MPa, reach final grouting pressure and continue more than slip casting 10min, mud jacking 4~5 times, injection speed 20~30L/min, each slip casting intermittent time takes 30min；

Stabilization zone periphery slip casting uses dual slurry；Use neat slurry in the middle part of general shield driving section, stabilization zone, under wear building Dual slurry is used in the middle part of section, stabilization zone.