Shield tunnel ground surface settlement stress detection device and pavement settlement treatment method

Abstract

The invention provides a shield tunnel ground surface settlement stress detection device and a pavement settlement treatment method, and relates to the technical field of shield tunnel construction. The detection device comprises a vertically arranged pipe body, the lower end of the pipe body is connected with a hollow elastic bag body, the upper end of the pipe body is connected with a water inlet pipe and an exhaust pipe, the water inlet pipe is provided with a pressure gauge and a water inlet valve, and the exhaust pipe is provided with an exhaust valve. According to the pavement settlement treatment method, an existing ground surface settlement detection mode is changed, measurement of the ground surface settlement amount is changed into measurement of the soil layer internal stress change amount, and a reliable basis is provided for pavement settlement treatment. According to the method, a ground surface settlement area and a soil layer stress reduction area can be quantitatively delineated according to the reduction amount of the water pressure of each elastic bag body, and then targeted grouting is performed, so that the soil layer stress is recovered to a stable and balanced state before tunnel excavation, and the problems of settlement and collapse of a paved pavement after a subway is opened are fundamentally solved.

Description

Technical Field

[0001] The present invention specifically relates to a shield tunnel surface settlement stress detection device and a road surface settlement control method, and relates to the technical field of shield tunnel construction. Background Art

[0002] While shield tunneling is the most effective method for tunnel construction, it can also cause soil unloading and surface subsidence. Many newly constructed subway lines experience subsidence and collapse of the paved road surface only after they have been in operation for some time.

[0003] Refer to the attached Figure 1 The main reason for paved road surface settlement and collapse is that most domestic subway tunnels 1 are built beneath existing paved roads 2. During tunnel construction, the paved road 2 must be fenced off and traffic is prohibited. The paved road 2 has a highly robust hardened layer due to long-term vehicle compaction. Even if the soil layer 3 settles during tunnel construction, no settlement is detected on the paved road 2. After the tunnel is opened to traffic, the paved road 2 breaks under the pressure of vehicles, causing settlement and collapse.

[0004] Refer to the attached Figure 2 To eliminate the impact of paved roads on surface settlement detection, the current settlement detection method used in engineering projects involves drilling holes in the pavement 2 and then inserting rebar 4 into the soil layer 3 to measure the settlement of the rebar 4. This settlement detection method has two major problems: First, the measurement is unreliable. This is because settlement is related to many factors. For example, some soils have high cohesion. After excavation, the lower soil layer loses, and the upper soil layer forms a vault structure, resulting in no or limited settlement of the rebar. Second, even if the actual surface settlement is detected, it can only roughly reflect the severity of the settlement. For pavement settlement control, this settlement value has no practical guiding significance. In essence, the process of tunnel excavation is also a process of rebalancing various stresses within the soil layer. These stresses include the compressive stresses exerted by ground structures on the soil layer. The soil loss caused by tunnel excavation creates voids, disrupting the stress balance of the original soil layer. As the soil deforms and settles, the stresses within the reconstructed soil layer are rebalanced. Therefore, the stress in the soil layer before and after settlement is different. Generally speaking, the stress in the soil layer after settlement is released to a certain extent, and its stress is less than the stress before settlement.

[0005] Grouting is commonly used to manage road subsidence in existing technologies, which has the advantage of not requiring damage to the paved surface. However, if surface subsidence is used as the basis for treatment, with the volume of cement slurry injected proportional to the amount of subsidence, the road surface will likely continue to sink and collapse. Therefore, it is necessary to change the existing method of detecting surface subsidence.

[0006] Search literature: Qian Jiazhi's paper "Analysis and Control Research on Surface Settlement of Shield Tunneling Under Existing Railway" explains the mechanism of surface settlement. The cause of surface settlement is soil deformation caused by stress imbalance after soil loss.

[0007] A roadbed settlement monitoring device (Chinese patent CN211601930U) uses a rubber water bag. However, this rubber water bag is only used to increase the sensitivity of settlement measurement. Moreover, this settlement measurement method measures the amount of surface subsidence, not the amount of stress change within the soil layer. It cannot solve the problem of settlement and collapse of paved roads after the opening of subways. Summary of the Invention

[0008] In order to overcome the shortcomings of the background technology, the present invention discloses a shield tunnel surface settlement stress detection device and a road surface settlement control method, the purpose of which is: 1. Change the existing detection method of surface settlement to provide a basis for road settlement control; 2. Solve the problem of settlement and collapse of paved road surface after the opening of subway.

[0009] The present invention adopts the following technical solutions: A shield tunnel surface settlement stress detection device includes a vertically arranged tube body, a hollow elastic bag connected to the lower end of the tube body, a water inlet pipe and an exhaust pipe connected to the upper end of the tube body, a pressure gauge and a water inlet valve installed on the water inlet pipe, and an exhaust valve installed on the exhaust pipe.

[0010] Preferred improved technical solution: the elastic capsule has a spherical or cylindrical shape.

[0011] A method for controlling road subsidence comprises the following steps: S1: Drill holes on the road surface along the planned subway route, with at least three test holes drilled on each section; S2: Insert detection devices of different lengths into the detection hole in sequence. Each time a detection device is inserted, the elastic capsule at the lower end of the detection device is filled with backfill soil. After the detection device is installed, the backfill soil is compacted and the opening of the detection hole is sealed. S3: Open the water inlet valve to inject water into the elastic bladder and pressurize it until the water pressure indicated by the pressure gauge reaches the preset value, and then close the water inlet valve; S4: After the shield tunnel is constructed, the water pressure changes indicated by each pressure gauge are recorded, and the surface settlement areas and soil stress reduction areas are delineated based on the amount of water pressure reduction. Grouting is then carried out in the surface settlement areas and soil stress reduction areas until the water pressure indicated by each pressure gauge returns to the preset value.

[0012] The preferred improved technical solution also includes step S5: opening the exhaust valve to release the pressure, removing the detection device from the detection hole, and then injecting grout into the detection hole.

[0013] Preferred improved technical solution: In S2, a sealing disk with radial slots is provided at the orifice, and the sealing disk is fixed to the road surface by expansion bolts.

[0014] Preferred improved technical solution: In S3, while injecting water, open the exhaust valve to exhaust air until the air in the detection device is completely discharged, and then close the exhaust valve.

[0015] After implementing the above technical solution, compared with the background technology, the present invention can produce the following beneficial effects: 1. This invention changes the existing method of detecting surface settlement by measuring the stress change in the soil layer instead of measuring the surface settlement, thus providing a reliable basis for the settlement control of the road surface. 2. The present invention can quantitatively identify the surface settlement area and the soil stress reduction area based on the reduction in water pressure of each elastic bladder, and then carry out targeted grouting in the surface settlement area and the soil stress reduction area to restore the soil stress to the stable equilibrium state before tunnel excavation, fundamentally solving the problem of settlement and collapse of the paved road surface after the opening of the subway. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attachment Figure 1 Shown is a schematic diagram of the settlement of an existing paved road surface.

[0017] Attachment Figure 2 Shown is a schematic diagram of existing surface settlement detection.

[0018] Attachment Figure 3 Shown is a schematic diagram of the three-dimensional structure of the detection device.

[0019] Attachment Figure 4 Shown is a schematic diagram of the distribution of detection holes.

[0020] Attachment Figure 5 Shown is a schematic diagram of the planar structure of the detection device installed in the detection hole.

[0021] Attachment Figure 6 Shown is a schematic diagram of the three-dimensional structure of the detection device installed in the detection hole.

[0022] Attachment Figure 7 Shown is a schematic diagram of the installation structure of the sealing disk.

[0023] Attachment Figure 8 Shown is a schematic diagram of the elastic bladder being pressurized and expanded.

[0024] Attachment Figure 9Shown is a schematic diagram of soil settlement after tunnel excavation.

[0025] Attachment Figure 10 Shown is a schematic diagram of grouting in the settlement area.

[0026] Attachment Figure 11 Shown is a schematic diagram of the road surface after settlement treatment.

[0027] In the attached figure: 1. Tunnel; 2. Paved road surface; 3. Soil layer; 4. Rebar; 5. Detection device; 5.1. Pipe body; 5.2. Elastic bladder; 5.3. Water inlet pipe; 5.4. Exhaust pipe; 5.5. Pressure gauge; 5.6. Water inlet valve; 5.7. Exhaust valve; 6. Sealing disk; 6.1. Radial slot; 7. Expansion bolt; 8.1. Planned subway route; 8.2. Detection hole; 8.3. Surface settlement area; 8.4. Soil stress reduction area; 8.5. Grouting pipe. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these preferred embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. It should be noted that in the description of the present invention, terms such as "front", "rear", "up", "down", "left", "right", "vertical", "horizontal", "inside", and "outside" that indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is merely for the convenience of description and does not indicate or imply that the device or component must have a specific orientation and positional relationship. Therefore, it should not be understood as a limitation of the present invention. It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a communication between the two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0029] A shield tunnel surface settlement stress detection device and a road surface settlement control method relate to the technical field of shield tunnel construction and are mainly used to solve the problem of settlement and collapse of paved roads after the opening of subways.

[0030] Refer to the attached Figure 3. The shield tunnel surface settlement stress detection device 5 includes a vertically arranged tube body 5.1, and a hollow elastic capsule 5.2 is connected to the lower end of the tube body 5.1. The elastic capsule 5.2 is made of rubber and its shape can be spherical or cylindrical. A water inlet pipe 5.3 and an exhaust pipe 5.4 are connected to the upper end of the tube body 5.1. A pressure gauge 5.5 and a water inlet valve 5.6 are installed on the water inlet pipe 5.3, and an exhaust valve 5.7 is installed on the exhaust pipe 5.4. The function of the water inlet pipe 5.3 and the water inlet valve 5.6 is to inject water into the elastic capsule 5.2 and pressurize it to cause the elastic capsule 5.2 to expand. The function of the exhaust pipe 5.4 and the exhaust valve 5.7 is to discharge the air in the elastic capsule 5.2 during the water injection process. The function of the pressure gauge 5.5 is to measure the water pressure in the elastic capsule 5.2 in real time.

[0031] In order to specifically illustrate the function of the detection device, the present invention also discloses a road surface settlement control method, comprising the following steps: S1: Drill holes along the planned subway route 8.1 on the paved road surface, with at least three test holes 8.2 drilled on each section.

[0032] Refer to the attached Figure 4 In this embodiment, five holes are drilled at equal intervals on each section, wherein the middle detection hole 8.2 is located on the center line of the planned subway line 8.1.

[0033] S2: Insert the detection devices 5 of different lengths into the hole in sequence. Each time a detection device 5 is inserted, the elastic capsule 5.2 at the lower end of the detection device 5 is filled with backfill soil. After the detection device is installed, the backfill soil is compacted and the opening of the detection hole 8.2 is sealed.

[0034] Refer to the attached Figure 5 and attached Figure 6 Surface cross-sectional settlement follows a normal curve distribution. Therefore, more detection devices 5 can be installed in the detection hole 8.2 on the tunnel's central axis, while fewer detection devices 5 can be installed in the detection holes 8.2 on either side. In this embodiment, six detection devices 5 are inserted into the central detection hole 8.2, and four and two detection devices 5 are inserted into the detection holes 8.2 on either side, respectively. The detection devices 5 have equal length differences.

[0035] The purpose of using backfill soil to fill the elastic bladder is to expel the air within test hole 8.2 and integrate the elastic bladder 5.2 with the existing soil. Tamping the backfill soil eliminates voids and restores the original pressure of the soil at the test hole. Sealing the hole opening prevents the soil within test hole 8.2 from being pushed upward when pressurized by the elastic bladder 5.2, which could affect the detection results. The diameter of test hole 8.2 is only 9 cm, so backfilling and tamping will not disrupt the stress balance of the original soil layer 3.

[0036] Refer to the attached Figure 7 To seal the orifice, a sealing disc 6 is installed at the orifice and secured to the paved road surface 2 via expansion bolts 7. Depending on the number of detection devices 5 to be inserted, a plurality of radial slots 6.1 are provided along the circumference of the sealing disc 6. These slots 6.1 create space to facilitate installation of the sealing disc 6 at the orifice.

[0037] S3: Refer to the attached Figure 3 and attached Figure 8 , open the water inlet valve 5.6 to inject water into the elastic bladder 5.2 and pressurize it until the water pressure indicated by the pressure gauge 5.5 reaches the preset value, and then close the water inlet valve 5.6.

[0038] The purpose of injecting water and applying pressure to the elastic bladder is to cause it to expand, thereby exerting a preload on the surrounding soil, much like applying pressure before taking a blood pressure test. As the stress in the surrounding soil changes, the volume of the bladder, and therefore the water pressure within it, also changes.

[0039] The reason for injecting water into the elastic bladder 5.2 instead of air is that water is incompressible and can exert a pressure of 3 MPa or even greater on the elastic bladder. To expel the air from the elastic bladder 5.2, the exhaust valve 5.7 is opened while the water is being injected until all the air in the detection device 5 is exhausted, and then the exhaust valve 5.7 is closed.

[0040] S4: After the shield tunnel is constructed, the water pressure changes indicated by each pressure gauge 5.5 are recorded, and the surface settlement area 8.3 and the soil stress reduction area 8.4 are delineated according to the amount of water pressure reduction. Grouting is then performed in the surface settlement area 8.3 and the soil stress reduction area 8.4 until the water pressure indicated by each pressure gauge 5.5 returns to the preset value.

[0041] Refer to the attached Figure 9 During tunnel construction, soil loss caused by excavation disrupts the stress balance of the original soil layer. As the soil deforms and settles, the stress within the reconstructed soil layer is rebalanced. After settlement, the stress within layer 3 is somewhat relieved, becoming less than the pre-settlement stress. This is manifested by the appearance of surface settlement area 8.3 and soil stress reduction area 8.4 above tunnel 1.

[0042] Because the present invention incorporates multiple detection devices 5 within the detection hole, surface settlement areas 8.3 and soil stress reduction areas 8.4 can be delineated based on the water pressure changes indicated by the pressure gauges 5.5. For example, if the water pressure indicated by the pressure gauge of the lowest elastic bladder in the middle measurement hole remains essentially unchanged, this indicates that the stress in the soil layer within the elastic bladder remains essentially unchanged, or has returned to its original state after a change. If the water pressure indicated by the pressure gauges of the three elastic bladders in the middle is lower than a preset value, this indicates that these three elastic bladders are within soil stress reduction area 8.4, indicating that the soil within this area has previously deformed and settled, and that the stress on soil layer 3 has been significantly reduced. If the water pressure indicated by the pressure gauges of the two elastic bladders at the top is significantly lower than a preset value, this indicates that these two elastic bladders are within surface settlement area 8.3, indicating that a hidden subsidence area exists beneath the paved road surface 2.

[0043] Since the surface cross-sectional settlement is distributed in a normal curve, the width and amplitude of the settlement area can be estimated based on the reduction in water pressure of each elastic bladder 5.2, and then the surface settlement area 8.3 and the soil stress reduction area 8.4 can be quantitatively delineated.

[0044] Refer to the attached Figure 10 Once the surface settlement area 8.3 and the soil stress reduction area 8.4 are identified, grouting can be carried out in targeted fashion using the grouting pipes 8.5 until the water pressure indicated by the pressure gauges 5.5 returns to the preset value. At this point, the stress in the soil layer 3 has essentially returned to the stable equilibrium state prior to tunnel 1 excavation. Even after the tunnel is opened to traffic, the paved road surface 2 will not experience settlement or collapse.

[0045] S5: Refer to the attached Figure 3 and attached Figure 11 , open the exhaust valve 5.7 to relieve the pressure, then remove the blocking plate 6 and take out the detection device 5 from the detection hole 8.2, and then inject grout into the detection hole 8.2 to complete the repair of the road surface and the control of settlement.

[0046] It is worth noting that the contents not described in detail in the above embodiments are prior art. It is also worth noting that for those skilled in the art, any additions, subtractions, replacements and improvements made under the structure and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A shield tunnel surface settlement stress detection device, characterized by: It includes a vertically arranged tube body, a hollow elastic bag connected to the lower end of the tube body, a water inlet pipe and an exhaust pipe connected to the upper end of the tube body, a pressure gauge and a water inlet valve installed on the water inlet pipe, and an exhaust valve installed on the exhaust pipe.

2. The shield tunnel surface settlement stress detection device according to claim 1, characterized in that: The elastic capsule has a spherical or cylindrical shape.

3. A method for controlling road subsidence using the detection device according to claim 1, characterized in that: The following steps are involved: S1: Drill holes on the road surface along the planned subway route, with at least three test holes drilled on each section; S2: Insert detection devices of different lengths into the detection hole in sequence. Each time a detection device is inserted, the elastic capsule at the lower end of the detection device is filled with backfill soil. After the detection device is installed, the backfill soil is compacted and the opening of the detection hole is sealed. S3: Open the water inlet valve to inject water into the elastic bladder and pressurize it until the water pressure indicated by the pressure gauge reaches the preset value, and then close the water inlet valve; S4: After the shield tunnel is constructed, the water pressure changes indicated by each pressure gauge are recorded, and the surface settlement areas and soil stress reduction areas are delineated based on the amount of water pressure reduction. Grouting is then carried out in the surface settlement areas and soil stress reduction areas until the water pressure indicated by each pressure gauge returns to the preset value.

4. A road surface settlement treatment method according to claim 3, characterized in that: The method further includes step S5: opening the exhaust valve to release the pressure, taking the detection device out of the detection hole, and then injecting grout into the detection hole.

5. A road surface settlement treatment method according to claim 3, characterized in that: In S2, a sealing disk with radial slots is provided at the orifice, and the sealing disk is fixed to the road surface by expansion bolts.

6. A road surface settlement treatment method according to claim 3, characterized in that: In S3, while injecting water, the exhaust valve is opened to exhaust air until the air in the detection device is completely exhausted, and then the exhaust valve is closed.

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