CN110805052A - Comprehensive treatment method for sudden surge of ultra-deep foundation pit - Google Patents
Comprehensive treatment method for sudden surge of ultra-deep foundation pit Download PDFInfo
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- E—FIXED CONSTRUCTIONS
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- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/10—Restraining of underground water by lowering level of ground water
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
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Abstract
The invention provides a comprehensive treatment method for sudden surge of an ultra-deep foundation pit, which comprises the steps of firstly adopting an ultra-deep well pressure reduction technology to control the pressure and water level of pressure-bearing water in a deep soil body, ensuring dry tank operation and enabling the additional settlement of the ground to be within the allowable range of surrounding buildings; then monitoring the stress in the stratum and the change of the balance environment after the soil mass groundwater inrush and drainage descending through a deep foundation pit informatization technology, and accurately judging the deep soil mass stress influence range caused by the foundation pit inrush; then, a rapid gelling micro-expansion material is filled on a flow line of underground water in a high-pressure flushing manner, slurry generated by the disturbance of a foundation pit soil body after the inrush phenomenon is replaced, a reinforcing material and the underground water are subjected to chemical reaction and then rapidly solidified to fill gaps and holes of the soil layer, and the soil body settlement or foundation pit structure inclination caused by the change of a stress field is limited; and the construction period pressure caused by the occurrence of the surge and the adverse effect on the surrounding environment can be reduced as much as possible.
Description
Technical Field
The invention belongs to the technical field of ultra-deep foundation pit construction, and particularly relates to a processing method for ultra-deep foundation pits when inrush occurs.
Background
In recent years, foundation pit engineering in industrial and civil construction projects is developed deeply, geological conditions of construction sites are complex, the hydraulic action of underground water in a natural state is weak, the thickness of a water-resisting layer coated on a confined aquifer is reduced by excavating the foundation pit, the natural dynamic balance condition of the underground water is changed, and when the water-resisting layer is reduced to a certain degree, the water head pressure of confined water can crack or damage a foundation pit bottom plate to cause a surge phenomenon. If the confined aquifer is a fine sand layer, the base is easy to generate the phenomenon of water spraying and sand bleeding, if the confined aquifer is not treated in time, serious geotechnical engineering hazards can be caused, and serious quality and safety accidents are caused.
At present, the treatment on the foundation pit inrush at home mainly adopts: firstly, the excavation depth of the foundation pit is controlled, so that the base water-resisting layer is reserved to a thickness which does not cause the inrush current; and secondly, drain holes are formed in the periphery of the foundation pit, so that the bearing water level is reduced, and the pressure of a bearing water head is reduced. However, if only a single drainage measure is used, the precipitation process may cause excessive settlement and potential damage to the surrounding environment of the project, and the control effect is not satisfactory.
Disclosure of Invention
The invention aims to solve the problem of adverse effect on engineering when the deep foundation pit construction has the surging, provides a treatment method which has strong operability, is concise and concise in construction, is economic and safe, and can effectively ensure the quality, effectively controls the additional harm of underground water to project environment while controlling the harm of the underground water to the foundation pit, and enables the whole treatment effect to reach the optimal degree.
The specific technical scheme of the invention is as follows:
a comprehensive treatment method for sudden surge of an ultra-deep foundation pit comprises the following steps:
firstly, effectively controlling the pressure and water level of the pressure-bearing water in the deep soil body by adopting an ultra-deep well pressure reduction technology, ensuring the operation of a dry tank and ensuring the additional settlement of the ground to be within the allowable range of surrounding buildings;
then monitoring the stress in the stratum and the change of the balance environment after the soil mass groundwater inrush and drainage descending through a deep foundation pit informatization technology, and accurately judging the deep soil mass stress influence range caused by the foundation pit inrush;
and then, a rapid gelling micro-expansion material is filled on a flowing line of underground water in a high-pressure flushing manner, slurry generated by the disturbance of a foundation pit soil body after the sudden surge is replaced, and the reinforcing material is rapidly solidified and filled in gaps and holes of the soil layer after a chemical reaction with the underground water, so that the soil body sedimentation or foundation pit structure inclination caused by the change of a stress field is limited, and the ground stress field is restored to the original level.
The invention has the beneficial effects that: quality and safety risks possibly brought to engineering by the deep foundation pit inrush phenomenon are effectively treated in time; and the construction period pressure caused by the occurrence of the surge and the adverse effect on the surrounding environment can be reduced as much as possible.
The concrete construction of the invention is carried out according to the following steps:
firstly, manufacturing a deep well pipe: (1) determining deep well design and control parameters according to the work and documents; (2) the deep well pipe is manufactured by spiral welded pipes with the diameter of 529mm in a field segmentation manner, the total length is determined by the bottom elevation of a pressure-bearing water layer, the length of each segment is controlled to be within 15m, the deep well pipe is composed of a common well wall pipe and a filter pipe segment, and the last segment of the filter pipe segment is welded at the bottom end to form a conical seal; (3) the filter pipe section is arranged in the pressure-bearing water level area, and the total manufacturing length L1 of the filter pipe section is greater than the thickness H of the calculated pressure-bearing water layer; cutting quincuncial long-strip water filtering holes on the spiral welded pipe; a filter screen is arranged outside the filter pipe section, the filter screen is of a double-layer structure, the inner layer is a nylon gauze, the outer layer is a steel gauze, and the two layers wrap the filter pipe section; medium and fine sand with the thickness of 100mm is filled outside the filter screen, and the filling height exceeds the top of the filter by 3-5 m; filling clay pellets on the middle fine sand layer to seal and isolate the middle fine sand layer from the upper soil layer; (4) the pipe sections except the filtering pipe section are all common well wall pipes with solid pipes and no holes; (5) and determining the dosage of the single-well filter material through calculation.
And secondly, a mud wall protection rotary drilling process is adopted for forming the well of the deep well, the key parameters such as verticality, depth, well diameter and the like are well controlled in the drilling process, the filter tube is firstly lifted and installed by a 50t truck crane for the deep well tube, then other well wall tubes are lifted, and the interface between each section of the well wall tubes is welded firmly by electric welding.
Thirdly, installing a deep-well pump: the pump head is controlled at 3-5m under pressure when the deep-well pump is installed, the well is washed by high-pressure air after installation, clean water is injected while washing for circulation until clean water is discharged from the well, the water level controller is installed, the lower water level limiter is installed at the same elevation position with the pump head, the upper water level controller is installed at the position 3-5m higher than the top of the filter, the water pump is started to drain when the water level rises to the upper water level controller, the water pump stops draining when the water level drops to the lower water level limiter, 5-stage pressurization of the large-lift deep-well pump is adopted for ultra-external intermittent drainage, and a flow meter is installed to observe the water discharge amount during drainage.
And fourthly, arranging soil pressure observation points and settlement observation points around the foundation pit according to the specific foundation pit condition to test the stress change, displacement and observation water level change condition of the soil body, monitoring the stress in the stratum and the change of the balance environment after the ground water of the deep foundation pit suddenly gushes or is drained in real time, judging the stress influence range of the deep soil body caused by the sudden gushing of the foundation pit, comparing settlement observation records after the field construction is finished for a period of time, and observing whether the settlement is reduced or stopped.
And fifthly, selecting reasonable process parameters according to the range and the depth to be treated, filling the cement-water-glass double-liquid reinforcing material on a flow line of underground water in a high-pressure flushing manner, replacing slurry generated by the disturbance of the foundation pit soil body after the sudden surge occurs, and quickly solidifying and filling gaps and holes of the soil layer after the reinforcing material and the underground water perform chemical reaction to limit the soil body settlement or foundation pit structure inclination caused by the change of the stress field so as to restore the ground stress field to the original level.
In the construction, the concrete operation of the fifth step is as follows:
(1) grouting drill hole
After positioning according to the measured hole positions, the rotary drilling machine is in place to drill, and the drilling is performed according to the sequence that the upper hole, the middle hole, the lower hole, the left hole and the right hole are staggered, and the long hole and the short hole are staggered.
(2) Installation slip casting pipe
Whether the hole collapses or not is checked after the drilling is finished, the grouting pipe can be placed below the rear part, the position of the grout stop plug is determined, double pipes are bound into a whole in a flush mode during installation, and the grouting hole of the lower section of the pipe is wound by a plastic transparent adhesive tape to prevent hole blockage during placement of the pipe.
(3) Conducting a pressurized Water test
When water is pressurized, a single pump is started to pressurize water firstly, then another single pump is started to pressurize water, whether the mixer is mixed with water or not is checked, the pressure of the pressurized water is gradually increased to the preset grouting pressure from small pressure and lasts for several minutes, the water permeability of the soil layer is measured, the permeability of the soil layer is verified, and a modification basis is provided for selecting pump capacity, pump pressure and slurry ratio during grouting; and simultaneously checking the effect of the grout stop plug and the leakage phenomenon of the grouting pipe.
(4) Grouting
The feeding sequence when the cement slurry is stirred is as follows: water, retarder and cement, wherein the stirring time is not less than 5 minutes, and the standing time is not more than 3 minutes; when the holes are arranged in two rows, the inner ring hole is firstly injected in a pressing mode, then the outer ring hole is injected in a pressing mode, the pressing pressure is controlled in the pressing process, and the pressing is carried out in the sequence of small first and big second; recording parameters such as injection amount, depth, pressure and the like in the injection pressing process; stopping pressure injection when the end condition is reached; on site, judging according to the grouting amount and diffusion of a single hole, if rapid gelation is needed, controlling the volume ratio C to S of the cement paste and the water glass, wherein the C to S is 1:1, and the C to S can be 1:0.6 when the cement running or hole sealing is finished.
The width of the water filtering holes is 20mm, the length of the holes is 200mm, and the transverse and transverse spacing of the holes is 100 mm.
The inner layer of the filter screen is a nylon gauze with 120 meshes, the outer layer is a steel gauze with 80 meshes, and the two layers wrap the filter pipe section. The steel sand net plays a role in primary filtration and simultaneously plays a role in protection, and the gauze net is prevented from being damaged in the construction process.
Soil pressure observation points and settlement observation points are arranged around the foundation pit, and a soil pressure box and an inclinometer pipe are embedded in the soil body.
Drawings
FIG. 1 is a schematic diagram of a deep well according to the present invention;
FIG. 2 illustrates an external deep well protection structure;
FIG. 3 is a schematic view of a filter tube segment.
In the figure, a filter pipe section 1, a pressure water layer 2, a spiral welding pipe 3, a water filtering hole 4, a nylon gauze 5, a steel gauze 6 and a medium fine sand layer 7.
Detailed Description
The invention combines the normal construction of the foundation pit and the processing process when the inrush occurs to carry out detailed and complete description on the construction of the ultra-deep foundation pit.
The invention provides a comprehensive treatment method for sudden surge of an ultra-deep foundation pit, which comprises the following steps of firstly, effectively controlling the pressure and water level of the bearing water in a deep soil body by adopting an ultra-deep well pressure reduction technology, ensuring dry tank operation and enabling the additional settlement of the ground to be within the allowable range of surrounding buildings; then monitoring the stress in the stratum and the change of the balance environment after the soil mass groundwater inrush or drainage descending through the deep foundation pit informatization technology, and accurately judging the deep soil mass stress influence range caused by the foundation pit inrush; and then, a rapid gelling micro-expansion material (high-pressure filling is carried out on a flowing line of underground water, mud generated by foundation pit soil body disturbance after the sudden surge is replaced, and a reinforcing material and the underground water are subjected to chemical reaction and then rapidly solidified and filled in gaps and holes of a soil layer, so that the soil body sedimentation or foundation pit structure inclination caused by the change of a stress field is limited, and the ground stress field is recovered to the original level.
Wherein the rapid gelling micro-expansion material is a cement-water-glass two-fluid reinforcing material.
The comprehensive treatment method for the ultra-deep foundation pit inrush is described by combining a specific construction example as follows:
the deep well design and control parameter table in the foundation pit engineering comprises the following steps:
secondly, with reference to fig. 1-3, the construction method comprises the following specific steps:
production of deep well pipe
(1) The related art parameter requires obtaining deep well design and control parameters with reference to table 1. (2) The spiral welded pipe 3 with the diameter of 529mm is manufactured in a field subsection mode, the total length is determined by the bottom elevation of 2 layers of a pressure-bearing water layer, the length of each section is controlled within 15m, the spiral welded pipe is composed of a common well wall pipe and a filter pipe section 1, the last section of the filter pipe section is welded at the bottom end to form a conical seal for installation, and the spiral welded pipe is shown in figure 1. (3) As shown in fig. 1, the total length L1 of the filter pipe section 1 is greater than the calculated thickness H of the pressure-bearing water layer 2, the filter pipe section is arranged in a pressure-bearing water level area, plum blossom-shaped long strip-shaped water filtering holes 4 are cut on the spiral welded pipe 3 by gas welding, the hole width is 20mm, the hole length is 200mm, the transverse and transverse spacing of the holes is 100mm, and the holes are arranged in a plum blossom shape; referring to fig. 2, a filter screen is arranged outside the filter pipe section, the filter screen is of a double-layer structure, the inner layer is made of a 120-mesh nylon gauze 5, the outer layer is made of an 80-mesh steel gauze 6, and the filter screen is wrapped in two layers, wherein the steel gauze plays a role in primary filtering and also plays a role in protection, and the gauze is prevented from being damaged in the construction process; in the depth of the filter section, medium and fine sand with the thickness of 0.25-0.5mm and the thickness of 100mm is filled outside the filter screen to play a role of coarse filtration, the filling height of the filter screen and the medium and fine sand layer 7 exceeds the top of the filter section by 3-5m, clay pellets are used for manual well filling and sealing to seal underground water in an upper soil layer, and the discharge of the underground water is as little as possible or not during the drainage period of the deep well, as shown in figure 3. (4) The rest sections are all solid pipes and ordinary casing pipes without holes. (5) And determining the dosage of the single-well filter material through calculation.
Secondly), a slurry wall protection rotary drilling process is adopted for forming the deep well, and key parameters such as verticality, depth, well diameter and the like are well controlled in the drilling process. The deep well pipe is firstly hoisted and installed with a filter pipe by a 50t truck crane, then other well wall pipes are hoisted, and the interface between every two sections of well wall pipes is firmly welded by electric welding.
Thirdly), installing a deep-well pump: when a deep well pump is installed, the pump head is controlled to be at a position 3-5m below the bearing water, after the deep well pump is installed, the well is washed by high-pressure air, clean water is injected while washing is carried out, after the clean water is discharged from the well, a water level controller is installed, a lower water level limiter can be installed at the same elevation position with the pump head, an upper water level controller is installed at a position 3-5m above the top of a filter, a water pump is started to drain when the water level rises to the position of the upper water level controller, and the water pump stops draining when the water level falls to the position of the lower water level limiter, so that. And 5-stage pressurization of a large-lift deep well pump is adopted for ultra-intermittent drainage, and a flow meter is installed during drainage to observe the drainage quantity.
And fourthly) arranging a soil pressure observation point, a settlement observation point and the like according to the concrete foundation pit conditions in a mode of embedding a soil pressure box, an inclinometer and the like in the soil around the foundation pit to test the stress change, displacement and observation water level change conditions of the soil, monitoring the stress in the stratum after the burst or drainage of the underground water of the soil of the deep foundation pit in real time and the change of the balance environment, and judging the stress influence range of the soil of the deep foundation pit caused by the burst of the foundation pit. And comparing the settlement observation records about 1 week after the site construction is finished, wherein the settlement is generally reduced or stopped.
Fifthly), selecting reasonable process parameters according to the range and the depth to be treated, adopting a rapid gelling micro-expansion material (a cement-water-glass double-liquid reinforcing material) to high-pressure fill on a flow line of underground water, and replacing slurry generated by foundation pit soil disturbance after the occurrence of the inrush.
(1) Grouting drill hole
After positioning according to the measured hole positions, the rotary drilling machine is in place to drill, and the drilling is performed according to the sequence that the upper hole, the middle hole, the lower hole, the left hole and the right hole are staggered, and the long hole and the short hole are staggered. Before drilling, the drilling machine is accurately positioned, when the hole is drilled, the pressure is lightly applied, the speed is slow, the water quantity is large, the drilling machine can firstly drill a certain depth by using a drill bit with a larger diameter, then the drilling machine can drill to the expected depth by using a drill bit with a smaller diameter.
(2) Installation slip casting pipe
And (5) checking whether the hole collapses or not after drilling, and determining that the grouting pipe can be placed at the rear part and determining the position of the grout stop plug. The grouting adopts a double-pipe grouting method, cement paste is injected by a slender steel pipe with the diameter of 6mm, and glass slurry is injected by a plastic pipe with the diameter of 6 mm. During installation, the double pipes are bound into a whole in parallel, and the grouting holes at the lower sections of the pipes are wound by plastic transparent adhesive tapes so as to prevent the holes from being blocked during the downward placement of the pipes.
(3) Conducting a pressurized Water test
When the water is pressurized, a single pump is started to pressurize the water, and then another single pump is started to pressurize the water, and whether the mixer is mixed with the water or not is checked. The pressurized water pressure is increased from a small step to a predetermined grouting pressure for several minutes. Measuring the water permeability of a soil layer, verifying the permeability of the soil layer, and providing a modification basis for selecting pump capacity, pump pressure and slurry ratio during grouting; and simultaneously checking the effect of the grout stop plug and the leakage phenomenon of the grouting pipe.
(4) Grouting
2 slurry storage tanks are arranged on site, and the cement slurry preparation and the water glass dilution are respectively arranged for storage. The feeding sequence when the cement slurry is stirred is as follows: water, retarder and cement, the stirring time is not less than 5 minutes, and the standing time is not more than 3 minutes. The inner ring holes are typically injected first, followed by the outer ring holes (in the case of double row holes). And (4) during grouting, controlling grouting pressure, and performing grouting in a sequence of small grouting first and large grouting second. And recording parameters such as injection amount, depth, pressure and the like in the injection pressing process. And stopping pressure injection when the end condition is reached. And judging on site according to the single-hole grouting amount and diffusion. If rapid gelling is required, it is achieved by controlling the volume ratio of cement paste to water glass, C: S, which is usually 1:1, and C: S, which is 1:0.6, can be used at the end of slurry run or hole sealing. In order to ensure the accuracy of the gel time, the prepared slurry must be sampled and tested during the grouting process, and the actual gel time of the slurry is measured by receiving the slurry at the slurry discharge port.
The soil body settlement or foundation pit structure inclination caused by the change of the stress field is limited by quickly solidifying and filling gaps and holes of the soil layer after the reinforcing material and the underground water are subjected to chemical reaction, so that the ground stress field is restored to the original level.
After the foundation pit is treated by the inrush, the measured data shows that key parameters such as the settlement of the foundation pit and the ground surface, the inclination measurement deformation, the stress change and the like are controlled within a preset range through the data sampling analysis and the settlement monitoring comparative analysis of the sensor, and the treatment effect reaches a satisfactory degree. The pressure reduction of the confined water of the ultra-deep well multistage pump reasonably controls the underground water pressure and the water level during the drainage period, does not cause the safety of the buildings around the foundation pit due to excessive additional settlement on the ground, enhances the soil strength of the deep soil body within the influence range of the inrush by the replacement filling ground stress recovery comprehensive technology, effectively eliminates the potential hazard of long-term settlement of the foundation pit and the buildings due to the change of the stress field of the deep soil body, enables the stress state to be basically recovered to the original state, and effectively controls the additional settlement on the ground to reduce the adverse effect of the inrush on the deep foundation pit and the buildings around the foundation pit to the maximum extent.
Claims (6)
1. A comprehensive treatment method for sudden surge of an ultra-deep foundation pit comprises the following steps:
firstly, effectively controlling the pressure and water level of the pressure-bearing water in the deep soil body by adopting an ultra-deep well pressure reduction technology, ensuring the operation of a dry tank and ensuring the additional settlement of the ground to be within the allowable range of surrounding buildings;
then monitoring the stress in the stratum and the change of the balance environment after the soil mass groundwater inrush and drainage descending through a deep foundation pit informatization technology, and accurately judging the deep soil mass stress influence range caused by the foundation pit inrush;
and then, a rapid gelling micro-expansion material is filled on a flowing line of underground water in a high-pressure flushing manner, slurry generated by the disturbance of a foundation pit soil body after the sudden surge is replaced, and the reinforcing material is rapidly solidified and filled in gaps and holes of the soil layer after a chemical reaction with the underground water, so that the soil body sedimentation or foundation pit structure inclination caused by the change of a stress field is limited, and the ground stress field is restored to the original level.
2. The comprehensive treatment method for the inrush of the ultra-deep foundation pit as claimed in claim 1, which is characterized in that: the concrete construction is carried out according to the following steps:
manufacturing a deep well pipe: (1) determining deep well design and control parameters according to the work and documents; (2) the deep well pipe is manufactured by spiral welded pipes with the diameter of 529mm in a field segmentation manner, the total length is determined by the bottom elevation of a pressure-bearing water layer, the length of each segment is controlled to be within 15m, the deep well pipe is composed of a common well wall pipe and a filter pipe segment, and the last segment of the filter pipe segment is welded at the bottom end to form a conical seal; (3) the filter pipe section is arranged in the pressure-bearing water level area, and the total manufacturing length L1 of the filter pipe section is greater than the thickness H of the calculated pressure-bearing water layer; cutting quincuncial long-strip water filtering holes on the spiral welded pipe; a filter screen is arranged outside the filter pipe section, the filter screen is of a double-layer structure, the inner layer is a nylon gauze, the outer layer is a steel gauze, and the two layers wrap the filter pipe section; medium and fine sand with the thickness of 100mm is filled outside the filter screen, and the filling height exceeds the top of the filter by 3-5 m; filling clay pellets on the middle fine sand layer to seal and isolate the middle fine sand layer from the upper soil layer; (4) the pipe sections except the filtering pipe section are all common well wall pipes with solid pipes and no holes; (5) determining the dosage of the single-well filter material through calculation;
secondly), a mud retaining wall rotary drilling process is adopted for forming a deep well, key parameters such as verticality, depth, well diameter and the like are well controlled in the drilling process, a filter tube is firstly hoisted and installed on the deep well tube by a 50t truck crane, then other well wall tubes are hoisted, and the interface between each section of the well wall tubes is welded firmly by electric welding;
thirdly), installing a deep-well pump: when a deep-well pump is installed, a pump head is controlled to be 3-5m under pressure water, after the deep-well pump is installed, a well is washed by high-pressure air, clean water is injected while washing is performed, after clean water is discharged from the well, a water level controller is installed, a lower water level limiter is installed at the same elevation position with the pump head, an upper water level controller is installed at the position 3-5m higher than the top of a filter, a water pump is started to drain when the water level rises to the position of the upper water level controller, the water pump stops draining when the water level drops to the position of the lower water level limiter, a large-lift deep-well pump 5-level pressurization mode is adopted for ultra-external intermittent drainage, and a flow;
fourthly) arranging soil pressure observation points and settlement observation points around the foundation pit according to the specific foundation pit condition to test the stress change, displacement and observation water level change condition of the soil body, monitoring the stress in the stratum and the change of the balance environment after the ground water of the deep foundation pit suddenly gushes or is drained in real time, judging the stress influence range of the deep soil body caused by the sudden gushing of the foundation pit, comparing settlement observation records after the field construction is finished for a period of time, and observing whether the settlement is reduced or stopped;
fifthly), selecting reasonable process parameters according to the range and depth to be treated, filling the slurry generated by the disturbance of the foundation pit soil body after the sudden surge is replaced by adopting a cement-water-glass double-liquid reinforcing material on a flow line of the underground water in a high-pressure flushing manner, and quickly solidifying and filling gaps and holes of the soil layer after the reinforcing material and the underground water are subjected to chemical reaction to limit the settlement of the soil body or the inclination of the foundation pit structure caused by the change of the stress field, so that the ground stress field is restored to the original level.
3. The comprehensive treatment method for the inrush of the ultra-deep foundation pit as claimed in claim 2, which is characterized in that: the concrete operation of the construction step five) is as follows:
(1) grouting drill hole
After positioning according to the measured hole positions, a rotary drilling machine is in place to drill, and the drilling is performed according to the sequence that an upper hole, a middle hole, a lower hole, a left hole and a right hole are staggered, and a long hole and a short hole are staggered;
(2) installation slip casting pipe
Checking whether collapse exists in the hole after drilling, determining that a grouting pipe can be placed downwards behind the hole, determining the position of a grout stop plug, binding double pipes into a whole in parallel during installation, and winding the grouting hole at the lower section of the pipe with a plastic transparent adhesive tape to prevent hole blockage during placement of the pipe;
(3) conducting a pressurized Water test
When water is pressurized, a single pump is started to pressurize water firstly, then another single pump is started to pressurize water, whether the mixer is mixed with water or not is checked, the pressure of the pressurized water is gradually increased to the preset grouting pressure from small pressure and lasts for several minutes, the water permeability of the soil layer is measured, the permeability of the soil layer is verified, and a modification basis is provided for selecting pump capacity, pump pressure and slurry ratio during grouting; simultaneously checking the effect of the grout stop plug and the leakage phenomenon of the grouting pipe;
(4) grouting
The feeding sequence when the cement slurry is stirred is as follows: water, retarder and cement, wherein the stirring time is not less than 5 minutes, and the standing time is not more than 3 minutes; when the holes are arranged in two rows, the inner ring hole is firstly injected in a pressing mode, then the outer ring hole is injected in a pressing mode, the pressing pressure is controlled in the pressing process, and the pressing is carried out in the sequence of small first and big second; recording parameters such as injection amount, depth, pressure and the like in the injection pressing process; stopping pressure injection when the end condition is reached; on site, judging according to the grouting amount and diffusion of a single hole, if rapid gelation is needed, controlling the volume ratio C to S of the cement paste and the water glass, wherein the C to S is 1:1, and the C to S can be 1:0.6 when the cement running or hole sealing is finished.
4. The comprehensive treatment method for the inrush of the ultra-deep foundation pit as claimed in claim 3, which is characterized in that: the width of the water filtering holes is 20mm, the length of the holes is 200mm, and the transverse and transverse spacing of the holes is 100 mm.
5. The comprehensive treatment method for the inrush of the ultra-deep foundation pit as claimed in claim 4, which is characterized in that: the inner layer of the filter screen is a nylon gauze with 120 meshes, the outer layer is a steel gauze with 80 meshes, and the two layers wrap the filter pipe section. The steel sand net plays a role in primary filtration and simultaneously plays a role in protection, and the gauze net is prevented from being damaged in the construction process.
6. The comprehensive treatment method for the inrush of the ultra-deep foundation pit as claimed in claim 5, which is characterized in that: soil pressure observation points and settlement observation points are arranged around the foundation pit, and a soil pressure box and an inclinometer pipe are embedded in the soil body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911054332.7A CN110805052A (en) | 2019-10-31 | 2019-10-31 | Comprehensive treatment method for sudden surge of ultra-deep foundation pit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911054332.7A CN110805052A (en) | 2019-10-31 | 2019-10-31 | Comprehensive treatment method for sudden surge of ultra-deep foundation pit |
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| Publication Number | Publication Date |
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Application publication date: 20200218 |