Method for controlling structural settlement by combined electro-osmosis and grouting on both sides of stratum

Abstract

This invention discloses a method for controlling structural settlement through combined grouting and electroosmosis reinforcement of two strata, belonging to the field of underground engineering technology. The method includes construction preparation and drilling; simultaneous pipe laying; simultaneous grouting-electroosmosis reinforcement; and construction completion. This invention eliminates the need to enter the structure's interior, avoiding damage and disruption to its normal service life. It achieves synergistic effects of grouting and electroosmosis, dissipating excess pore water pressure caused by bag grouting in real time, balancing structural heave and settlement caused by bag grouting and electroosmosis drainage, and controlling micro-deformation of the structure during the reinforcement process. By utilizing the synergistic reinforcement effect of bag grouting and electroosmosis drainage on the soil, it improves the reinforcement effect of the foundation strata, achieving efficient control of structural settlement after foundation reinforcement. This method is applicable to settlement control of in-service underground structures.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering technology, specifically relating to a structural settlement control method that combines grouting of strata on both sides with electroosmosis reinforcement. It is applicable to the precise settlement control of underground structures such as tunnels or underground stations in operation under non-stop operation conditions. Background Technology

[0002] Due to changes in the geological environment and disturbances from surrounding construction, excessive settlement accidents frequently occur in underground structures in soft soil strata during long-term service, directly threatening structural safety and normal service. Reinforcing the bottom strata of the settlement zone is the primary means of controlling underground structure settlement. However, existing underground structure settlement control technologies face the following bottlenecks: (1) Affects the normal service function of underground structures. Drilling holes inside underground structures for grouting the bottom strata requires damaging the structure, which affects the normal use of the structure during the operation.

[0003] (2) It causes additional deformation of the underground structure. The grouting reinforcement process of the foundation will cause the underground structure to heave and induce excess pore water pressure in the soil; after reinforcement, the excess pore water pressure dissipates, the soil undergoes consolidation settlement, and the tunnel settlement continues to develop.

[0004] (3) The reinforcement effect of the bottom stratum of the structure is limited. The soil at the bottom of the underground structure is affected by the grouting reinforcement on both sides. The compaction effect plays a dominant role. During the short-term reinforcement period, the soft clay is in a non-drained state, and the soil reinforcement effect is limited.

[0005] Therefore, developing a technology that can be implemented on the outside of the structure, has a good reinforcement effect, and has small deformation fluctuations for the settlement control of underground structures in soft soil strata is an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The present invention aims to provide a structural settlement control method for combined grouting and electroosmotic reinforcement of strata on both sides, in order to solve the technical problems of existing technologies such as the need to enter the underground structure for construction, additional deformation caused by grouting, and limited reinforcement effect.

[0007] To achieve the above objectives, the present invention provides a method for controlling structural settlement through combined grouting and electroosmosis reinforcement of strata on both sides, comprising the following steps: Drill holes on the ground surface on both sides of the underground structure to the soil layer to be reinforced below the foundation of the underground structure; A grouting pipe and a drainage-electrode integrated pipe are simultaneously lowered into the borehole. The drainage-electrode integrated pipe integrates the functions of a drainage channel and an electroosmotic electrode. The grouting pipe and the drainage-electrode integrated pipe are arranged at a predetermined distance on the cross-section of the borehole. During the service gap, the grouting system and the electroosmosis system are started simultaneously: grout is injected into the soil or the bag through the grouting pipe to compact the surrounding soil; at the same time, the drainage-electrode integrated pipe on the side of the borehole cross section closest to the grouting pipe is used as the anode, and the drainage-electrode integrated pipe on the side away from the grouting pipe is used as the cathode. DC power is connected to carry out electroosmosis, so that the pore water in the soil migrates to the cathode and is discharged through the borehole. The deformation data of the underground structure is collected in real time by a deformation monitoring system, and the grouting pressure and electroosmosis voltage are adjusted synchronously according to the structural deformation data to control the deformation of the underground structure, including settlement or uplift. Once the deformation reaches the preset target value and stabilizes, grouting and electroosmosis are stopped simultaneously.

[0008] Furthermore, the grouting pipe is a micro-disturbance grouting pipe or a bag grouting pipe; the two sides of the bag grouting pipe are secured with bags by metal clips, and the bags are set corresponding to the grout outlet holes of the grouting pipe, used to compress the surrounding soil through the expansion of the bags. Bag grouting can achieve a directional and controllable compaction effect, avoid disorderly diffusion of grout, and improve grouting efficiency.

[0009] Furthermore, after the integrated drainage-electrode pipe is lowered to a predetermined depth, coarse sand is backfilled into the borehole to form a coarse sand filling layer, and the pore water is discharged along the coarse sand filling layer. The coarse sand filling layer not only ensures the stability of the borehole wall, but also forms an efficient drainage channel, ensuring the smooth flow of electroosmotic drainage.

[0010] Furthermore, the boreholes are evenly distributed longitudinally along the underground structure to form a combined reinforcement grid; the verticality or inclination angle of the grouting pipes and drainage-electrode integrated pipes after being lowered into the boreholes meets predetermined requirements. The even distribution creates a continuous and uniform reinforcement area, avoiding reinforcement blind spots and ensuring the overall effectiveness of settlement control.

[0011] Furthermore, the grouting system employs low-pressure injection of cement-based grout, with the grouting pressure and rate adjusted in real time based on deformation monitoring data. Low-pressure grouting reduces severe disturbance to the soil, and real-time adjustment enables dynamic matching between the grouting process and structural deformation.

[0012] Furthermore, the deformation monitoring system includes a total station or displacement sensors for real-time acquisition of deformation data of the underground structure. When the deformation reaches a preset target value, the grouting pressure and electroosmosis voltage are simultaneously reduced until the deformation stabilizes. Closed-loop control is achieved through deformation data feedback, avoiding excessive uplift or settlement and realizing precise control of micro-deformation.

[0013] Furthermore, the underground structure is an operational tunnel or underground station structure. This invention involves operations entirely outside the tunnel, without interrupting operations, and can effectively meet the settlement control requirements of underground structures during operation.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) No interference with normal structural service: The entire operation is carried out on the outside of the structure, without the need to enter the underground structure, and does not affect the normal service of the structure. It is suitable for the settlement control requirements of underground structures in subway, intercity railway and other operations.

[0015] (2) Zero structural damage and minimal and controllable deformation: Compared with the internal opening of the structure to inject grout into the stratum, there is no need to damage the structure; the external grouting combined with electroosmosis for rapid consolidation results in small structural deformation, low deformation rate, and high deformation control precision.

[0016] (3) Grouting-electroosmosis are carried out simultaneously to suppress excess pore pressure and disturbance: the simultaneous operation realizes "grouting and drainage consolidation at the same time", which quickly dissipates excess pore water pressure, avoids soil disturbance and reconsolidation settlement, and significantly improves deformation control effect and stabilizes quickly.

[0017] (4) Wide range of applications: It is applicable to soft soil strata with low permeability and high water content, such as silt and silty soil, and covers settlement control of various underground structures such as operating shield tunnels and mining tunnels. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic diagram of the vertical construction outside the tunnel after it is put into operation. Figure 2 A schematic diagram of non-vertical construction outside the tunnel after it is operational; Figure 3 This is a structural diagram of an integrated drainage-electrode pipe.

[0019] In the diagram: 1. Ground surface; 2. Tunnel; 3. Tunnel track; 4. Drainage-electrode integrated pipe; 5. Insulated suspension rope and wire; 6. Grouting pipe; 7. Wire; 8. DC power supply; 9. Grouting hose; 10. Grouting pump; 11. Grouting flow control valve; 12. Total station; 13. Settlement monitoring point. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0021] Example 1 This embodiment takes the settlement control of an operational shield tunnel as an example to specifically illustrate the structural settlement control method of the present invention, which combines grouting and electroosmosis reinforcement of the strata on both sides, including: Step 1: Construction preparation and drilling; First, the settlement zones and reinforcement areas of the operating tunnel are determined through surveying. For example... Figure 1 As shown, the locations of the surface boreholes 1 on both sides of tunnel 2 are marked to determine the operation duration during the service downtime (such as nighttime shutdown periods).

[0022] Drilling equipment was used to drill holes at the surface 1, penetrating the soft soil overburden to the soil layer to be reinforced below the foundation of tunnel 2. The holes were evenly distributed along the longitudinal direction of tunnel 2, forming a joint reinforcement grid. Excavated soil was removed from the holes to maintain the structural stability of the hole walls and prevent collapse and instability.

[0023] Step 2: Synchronous tube lowering; The grouting pipe 6 and the drainage-electrode integrated pipe 4 are simultaneously lowered into the borehole, and the two are arranged at a predetermined interval on the cross-section of the borehole.

[0024] In this embodiment, the grouting pipe 6 can be a micro-disturbance grouting pipe or a bag grouting pipe. When a bag grouting pipe is used, a bag is tied to its outer side with metal clips, and the bag is positioned corresponding to the grout outlet of the grouting pipe. During pipe installation, a micro-disturbance grouting core pipe is inserted, and the end of the core pipe is wrapped with enameled cloth to prevent it from falling off and blocking the grout outlet. After installation, the pipe is stabilized for a certain period of time, during which yellow sand is backfilled into the hole multiple times to fill the gaps and facilitate close contact between the bag and the surrounding soil.

[0025] The integrated drainage-electrode pipe 4 combines drainage channels and electroosmotic electrode functions; its structure is as follows: Figure 3 As shown. An insulated suspension rope and a wire 5 are tied to the integrated drainage-electrode pipe 4. The insulated suspension rope is used to lower the electrode pipe to a preset depth using gravity, and the wire is used to connect to a DC power supply 8. During lowering, the preset depth is marked on the insulated suspension rope, and the electrode pipe is lowered to the preset depth using gravity. After lowering, coarse sand is backfilled into the borehole to form a coarse sand filling layer to ensure unobstructed drainage channels, allowing pore water to drain along the coarse sand filling layer. After backfilling, the borehole is left to stand for a certain period until it is completely stable.

[0026] Step 3: Simultaneous reinforcement via grouting and electroosmosis; After entering the service gap period, the compaction grouting system and the electroosmosis system are started simultaneously.

[0027] (1) Grouting operation: such as Figure 1As shown, the grouting pump 10 delivers grout to the grouting pipe 6 through the grouting hose 9 and the grouting flow control valve 11. In this embodiment, low-pressure injection of cement-based grout (water-cement ratio 0.5~0.6) is used, and the surrounding soft soil is compacted by squeezing through grout bubbles or bags. The grouting pressure and grouting rate are adjusted in real time according to the structural deformation monitoring data.

[0028] (2) Electroosmosis operation: The DC power supply 8 is connected synchronously, and the drainage-electrode integrated pipe 4 is connected through the wire 7. The drainage-electrode integrated pipe 4 with the end of the cross-section closest to the grouting pipe 6 being grouted is used as the anode, and the drainage-electrode integrated pipe 4 with the end of the cross-section furthest from the grouting pipe 6 being grouted is used as the cathode to carry out electroosmosis operation on the bottom soil layer of tunnel 2. Under the action of the electric field, the pore water in the soft soil migrates rapidly from the anode to the cathode and is discharged along the coarse sand filling layer in the borehole, dissipating the excess pore water pressure generated by grouting in real time.

[0029] During electroosmosis, the electric field gradient can be controlled by adjusting the output voltage of the DC power supply 8, thereby controlling the pore water migration rate and drainage rate.

[0030] (3) Deformation control: such as Figure 1 As shown, the deformation monitoring system includes a total station 12 and settlement monitoring points 13 set on the tunnel track 3, used to collect deformation data of tunnel 2 in real time. The structural deformation includes settlement or uplift. When the structural deformation reaches a preset target value, the grouting pressure and electroosmosis voltage are reduced simultaneously until the deformation stabilizes. Once the structural deformation reaches the preset target value and stabilizes, grouting and electroosmosis are stopped simultaneously.

[0031] Step 4: Construction completion.

[0032] After the corresponding grouting holes are reinforced, the power supply to the grouting flow control valve 11 connected to the corresponding electrode tube is turned off, and the remaining holes are then worked on sequentially. All construction is completed within the service downtime. After construction, tunnel deformation is continuously monitored, and the work is terminated once the deformation stabilizes.

[0033] Example 2 This embodiment 2 is basically the same as embodiment 1, except that: when the surface outside the underground structure does not have the conditions for vertical drilling, a non-vertical drilling method can be used. For example... Figure 2 As shown, the borehole is driven into the soil layer to be reinforced below the foundation of the underground structure at a predetermined inclination angle. The verticality or inclination angle of the grouting pipe 6 and the drainage-electrode integrated pipe 4 meet the predetermined requirements to ensure that the pipe body is located within the reinforcement zone. The remaining steps are the same as in Example 1.

[0034] Example 3 This embodiment 3 uses the settlement control of an operating underground station as an example. The difference from embodiment 1 is that the underground structure is the structure of an operating underground station. Holes are drilled on the ground surface outside the station, with the drilling depth reaching the soil layer to be reinforced below the station floor. Grouting pipes and drainage-electrode integrated pipes are evenly arranged along the longitudinal direction of the station to form a combined reinforcement grid. The remaining steps are the same as in embodiment 1.

[0035] In this invention, the synergistic effect of grouting and electroosmosis is reflected in the following aspects: (1) Grouting compacts the soil, producing a lifting effect; electroosmotic drainage consolidates the soil, producing a settlement effect. The two work simultaneously, and through deformation monitoring and feedback adjustment, precise control of structural deformation can be achieved.

[0036] (2) Excess pore water pressure is generated during grouting, and its magnitude is related to the grouting pressure increment and the Poisson's ratio of the soil. Electroosmosis drives pore water migration through electric field force, and the drainage rate is related to the electric field gradient, electroosmotic permeability coefficient, and drainage cross-sectional area. By simultaneously draining through electroosmosis, excess pore water pressure can be quickly dissipated, soil disturbance can be suppressed, and soil consolidation can be accelerated.

[0037] (3) Compared with simple grouting, the present invention can achieve "grouting and drainage consolidation at the same time", which can effectively avoid secondary settlement caused by the dissipation of excess pore water pressure after grouting, improve the immediate stability of the stratum reinforcement effect and the long-term effect of controlling structural settlement.

[0038] In practical engineering applications, the following parameter ranges can be selected based on geological conditions and deformation control requirements: Drilling spacing: 1.0m~3.0m, determined according to geological conditions and settlement control requirements; Grouting pressure: 0.2MPa~1.0MPa, low-pressure grouting is adopted, and the pressure is dynamically adjusted according to deformation monitoring data; Electroosmotic voltage: 24V~110V, electric field gradient 20V / m~50V / m; Grouting slurry: cement-based slurry, water-cement ratio 0.5~0.8; Service gap: usually 4 to 6 hours at night.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling structural settlement by combined electro-osmotic reinforcement of two-side stratum grouting, characterized in that, Includes the following steps: Drill holes on the surface outside the underground structure to the soil layer to be reinforced below the foundation of the underground structure; A grouting pipe and a drainage-electrode integrated pipe are simultaneously lowered into the borehole. The drainage-electrode integrated pipe integrates the functions of a drainage channel and an electroosmotic electrode. The grouting pipe and the drainage-electrode integrated pipe are arranged at a predetermined distance on the cross-section of the borehole. The grouting system and electroosmosis system are started simultaneously: grout is injected into the soil or bag through the grouting pipe to compact the surrounding soil; at the same time, the drainage-electrode integrated pipe on the side of the borehole cross section closest to the grouting pipe is used as the anode, and the drainage-electrode integrated pipe on the side away from the grouting pipe is used as the cathode. DC power is connected to carry out electroosmosis, so that the pore water in the soil migrates to the cathode and is discharged through the borehole. The deformation data of the underground structure is collected in real time by a deformation monitoring system, and the grouting pressure and electroosmosis voltage are adjusted synchronously according to the deformation data to control the deformation of the underground structure, including settlement and / or uplift. Once the structural deformation reaches the preset target value and stabilizes, grouting and electroosmosis are stopped simultaneously.

2. The method according to claim 1, wherein, The grouting pipe is a micro-disturbance grouting pipe or a bag grouting pipe; the outer side of the bag grouting pipe is tied with a bag by a metal buckle, and the bag is set with the grout outlet hole of the grouting pipe, which is used to compress the surrounding soil by expanding the bag.

3. The method according to claim 1, wherein, After the integrated drainage-electrode pipe is lowered to a predetermined depth, coarse sand is backfilled into the borehole to form a coarse sand filling layer, and the pore water is discharged along the coarse sand filling layer.

4. The method according to claim 1, wherein, The boreholes are evenly arranged longitudinally along the underground structure to form a joint reinforcement grid; the verticality or inclination angle of the grouting pipe and the drainage-electrode integrated pipe after being lowered into the boreholes meets the predetermined requirements.

5. The method for structural settlement control by combined electro-osmotic reinforcement with grouting in two sides of stratum according to claim 1, characterized in that, The grouting system uses constant low pressure to inject cement-based grout, and the grouting pressure and grouting rate are adjusted in real time according to deformation monitoring data.

6. The structural settlement control method for combined grouting and electroosmosis reinforcement of strata on both sides according to claim 1, characterized in that, The deformation monitoring system includes a total station or displacement sensor to collect deformation data of the underground structure in real time; when the deformation reaches the preset target value, the grouting pressure and electroosmosis voltage are reduced simultaneously until the deformation stabilizes.

7. The structural settlement control method for combined grouting and electroosmosis reinforcement of strata on both sides according to claim 1, characterized in that, The underground structure refers to an operational tunnel or underground station structure.

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