Karst cave treatment method during undercrossing of shield tunnel through karst cave

Abstract

The invention relates to the technical field of shield tunnel construction, and discloses a karst cave treatment method during undercrossing of a shield tunnel into a karst cave, which comprises the following steps: S1, positioning the position of the karst cave; s2, grouting drilling points are arranged on the ground, and the drilling depth reaches the top of the karst cave above; s3, a first-stage steel casing is installed in the drill hole; s4, grouting is conducted in the upper karst cave through the first-stage steel casing; s5, after grouting is conducted to the top of the first-stage steel casing, drilling is conducted again, grouting is conducted after drilling is conducted, and the operation is repeated multiple times; s6, a second-stage steel casing is welded to the top of the first-stage steel casing, and the first-stage steel casing and the second-stage steel casing are put down; according to the karst cave treatment method during undercrossing of the shield tunnel through the karst cave, the first-stage steel casing and the second-stage steel casing are installed in a graded mode, supporting is carried out layer by layer, and grouting reinforcement is carried out, so that the geological stability of a construction area is effectively improved, and the risks of karst cave collapse and stratum instability are avoided; and proper grout is selected for grouting treatment according to the type of the karst cave, so that the filling integrity and the reinforcing effect are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnel construction, in particular to a method for processing a karst cave when a shield tunnel passes under a karst cave. Background Art

[0002] Shield tunnel construction is an important technology in the construction of modern urban rail transit, underground integrated pipe corridors and other infrastructure. However, shield tunnels often face some challenges when passing through complex geological conditions, such as underground caves. The existence of caves will have a great impact on the advancement of shield machines and construction safety. Improper treatment may lead to serious consequences such as cave collapse, stratum instability and even shield machine jamming. Therefore, it is very necessary to pre-treat the caves before the shield tunnel passes through them.

[0003] At present, the treatment methods for caves mainly include grouting filling, reinforcement or bypass construction, among which grouting filling is the most commonly used cave treatment method. The grouting filling method injects slurry into the cave to fill the cavity and stabilize the stratum, thereby providing safety guarantee for the smooth advancement of the shield machine. However, the current grouting filling method also has certain shortcomings, such as: The existing grouting filling method usually cannot be completed entirely on the ground, and has problems of low construction efficiency and high processing cost. In addition, the stability after grouting also needs to be improved. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a method for treating a karst cave when a shield tunnel passes through a karst cave, which has the advantages of high construction efficiency, strong stability, and the entire process is completed on the ground.

[0005] (II) Technical solution In order to achieve the above-mentioned purpose of high construction efficiency, strong stability and completion of the whole process on the ground, the present invention provides the following technical solution: a method for treating a karst cave when a shield tunnel passes through a karst cave, comprising the following steps: S1. Locate the cave; S2. Arrange grouting drilling points on the ground, and the drilling depth reaches the top of the cave above; S3. Install a primary steel casing in the borehole; S4, grouting into the upper cave through the first-level steel casing; S5. After grouting to the top of the primary steel casing, drill again and grout after drilling, repeating several times; S6. Weld the secondary steel casing on the top of the primary steel casing, and lower the primary steel casing and the secondary steel casing; S7, continue drilling through the primary steel casing and the secondary steel casing to drill through the cave below; S8, injecting grout into the cave below through the primary steel casing and the secondary steel casing; S9. After grouting to the top of the primary steel casing, drill again and grout after drilling, repeating several times; S10. Repeat steps S6-S9 until the calibration depth is reached.

[0006] As a preferred technical solution of the present invention, in step S1, geological radar, three-dimensional seismic survey instrument and ultrasonic reflectometer are used to conduct geological survey on the construction area of ​​the shield tunnel line to determine the location, number, size and shape of the caves.

[0007] As a preferred technical solution of the present invention, according to the characteristics of the caves, the caves are divided into fully filled caves, semi-filled caves and cavity caves. The fully filled caves are filled with cement-water glass double liquid slurry, the semi-filled caves are filled with bentonite-cement slurry, and the cavity caves are filled with polyurethane slurry.

[0008] As a preferred technical solution of the present invention, it also includes step S301: through the primary steel casing, the groundwater in the cave is led out to the water reservoir on the ground through the water diversion pipe.

[0009] As a preferred technical solution of the present invention, it also includes step S201: arranging anchor drilling points on the ground, embedding one end of the anchor rod into the rock formation through the drilling, and connecting the other end to a steel frame support frame, and the steel frame support frame is fixed on the ground.

[0010] As a preferred technical solution of the present invention, in step S201, a load sensor is also installed on the anchor rod to monitor the stress state of the anchor rod in real time and feed the data back to the monitoring system.

[0011] As a preferred technical solution of the present invention, in step S201, a flexible connection cushion layer is further provided between the steel frame support frame and the ground to absorb stress fluctuations caused by geological deformation.

[0012] As a preferred technical solution of the present invention, the bottom end of the anchoring borehole is as deep as the bottom end of the steel casing.

[0013] As a preferred technical solution of the present invention, a flange is detachably mounted on the top of the steel casing.

[0014] As a preferred technical solution of the present invention, before step S4, the method further includes: injecting anti-seepage slurry into the surrounding area of ​​the cave through drilling holes to form a continuous anti-seepage curtain.

[0015] (III) Beneficial effects Compared with the prior art, the present invention provides a method for treating a karst cave when a shield tunnel passes through a karst cave, which has the following beneficial effects: 1. The method of treating the karst cave when the shield tunnel passes through the karst cave is to install the first-level steel casing and the second-level steel casing in stages, support them layer by layer and reinforce them with grouting, which effectively improves the geological stability of the construction area and avoids the risk of cave collapse and stratum instability.

[0016] 2. The method of treating the cave when the shield tunnel passes through the cave is to select suitable slurry for grouting treatment according to the type of cave, thus ensuring the integrity of the filling and the reinforcement effect.

[0017] 3. The method of treating the karst cave when the shield tunnel passes through the karst cave is to set anchor holes and steel frame support frames, combined with flexible connection cushions and load sensors, which not only further improves the reinforcement effect, but also can monitor the stress changes in the construction area in real time, ensuring the reliability and safety of the support system.

[0018] 4. The method of treating the karst cave when the shield tunnel passes through the karst cave solves the problem of groundwater retention and leakage in the karst cave by constructing a groundwater drainage system and an anti-seepage curtain, ensures the grouting effect, and reduces the impact of groundwater on the construction environment.

[0019] 5. The method for dealing with karst caves when the shield tunnel passes through karst caves is to set a quick-disassembly flange on the top of the steel casing, which can prevent the steel casing from sinking, improve the convenience and adaptability of construction operations, and meet the flexible construction needs under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the upper cave of the present invention; Figure 2 It is a schematic diagram of the lower cave of the present invention; Figure 3 It is a schematic diagram of the present invention during anchoring; Figure 4 It is an enlarged schematic diagram of the flange portion of the present invention.

[0021] In the figure: 1. Upper cave; 2. Lower cave; 3. Primary steel casing; 4. Secondary steel casing; 5. Flange; 6. Anchor rod; 7. Steel frame support frame; 8. Mounting hole; 9. Through hole; 10. Mounting bolt. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0024] Embodiment 1: See also Figure 1-Figure 4 A method for treating a karst cave when a shield tunnel passes through a karst cave comprises the following steps: Step 1: Locate the location of the cave. Specifically, use a variety of geological detection equipment such as geological radar, three-dimensional seismic survey instrument and ultrasonic reflectometer to conduct a full range of geological detection of the construction area of ​​the shield tunnel line. Through detection, the location, number, size and shape of the cave can be accurately determined, providing reliable data support for subsequent processing.

[0025] Step 2: Arrange grouting drilling points on the ground. According to the specific location of the cave, arrange the drilling points on the ground reasonably. The drilling depth should reach the top of the cave above to facilitate the subsequent casing installation and grouting operations.

[0026] Step three, install a primary steel casing 3 in the borehole. The top of the primary steel casing 3 protrudes 50 cm above the ground to facilitate subsequent construction operations. If groundwater is detected in the cave above, the groundwater in the cave can be led out to the ground reservoir through the primary steel casing 3 and the water diversion pipe, thereby effectively reducing the water pressure in the cave and avoiding the impact on the construction.

[0027] Step 4: inject grout into the upper cave 1 through the primary steel casing 3, and gradually reinforce the cave by layered filling.

[0028] Step 5: After grouting to the top of the primary steel casing 3, drill again to make the slurry collapse, and then grout again, repeatedly until the top of the upper cave 1 is fully filled and a stable reinforcement is formed.

[0029] Step 6: Weld the secondary steel casing 4 on the top of the primary steel casing 3, and then lower the primary steel casing 3 and the secondary steel casing 4 so that the primary steel casing 3 is located at the bottom of the upper cave 1; Step seven, continue drilling through the primary steel casing 3 and the secondary steel casing 4 to drill through the lower cave 2. If there is groundwater in the lower cave 2, the groundwater can also be led out to the surface reservoir through the water diversion pipe in the casing to ensure that the grouting process is not affected.

[0030] Step 8: Inject grout into the lower cave 2 through the primary steel casing 3 and the secondary steel casing 4 to ensure that the bottom of the lower cave 2 and the surrounding geology are fully reinforced.

[0031] Step 9: After grouting to the top of the primary steel casing 3, drill again and grout after drilling, repeat several times until the top of the cave 2 below is also fully filled.

[0032] Step 10: Repeat steps S6-S9 until the calibration depth is reached. The calibration depth can be determined according to construction requirements and can pass through multiple caves.

[0033] In the present invention, according to the characteristics of the cave, the cave is divided into a fully filled cave, a semi-filled cave and a cavity cave. The fully filled cave is filled with cement-water glass double liquid slurry, which has rapid solidification, high strength and excellent anti-seepage performance. The semi-filled cave is filled with bentonite-cement slurry, which has good filling performance and strong anti-seepage ability, and is suitable for areas filled with loose mud and sand. The cavity cave is filled with polyurethane slurry, which has strong expansion performance and good water-stopping effect, and is suitable for completely empty cavity and water seepage environment. Therefore, suitable slurry is selected for grouting treatment according to the type of cave, which effectively ensures the integrity of the filling and the reinforcement effect.

[0034] In this embodiment, before step four, it also includes: injecting anti-seepage slurry into the surrounding area of ​​the cave through drilling to form a continuous anti-seepage curtain, and solving the problem of groundwater retention and leakage in the cave by constructing a groundwater drainage system and an anti-seepage curtain, thereby ensuring the grouting effect and reducing the impact of groundwater on the construction environment.

[0035] like Figure 4 As shown, in the present invention, a flange 5 is detachably installed on the top of the steel casing. Specifically, mounting holes 8 are evenly opened on the top of the steel casing, and through holes 9 corresponding to the mounting holes 8 are evenly opened on the flange 5. Mounting bolts 10 pass through the through holes 9 and are installed in the mounting holes 8, so that the flange 5 can be fixed to the top of the steel casing, which can prevent the steel casing from sinking, improve the convenience and adaptability of the construction operation, and meet the flexible construction needs under complex working conditions. When it is necessary to sink, the flange 5 can be removed.

[0036] Embodiment 2: See also Figure 3 On the basis of the first embodiment, in this embodiment, anchor drilling points are arranged on the ground, holes are drilled along the drilling points, one end of the anchor rod 6 is implanted into the rock formation through the drilling hole, and the other end is connected to the steel frame support frame 7, and the steel frame support frame 7 is fixed on the ground to form an overall support system.

[0037] like Figure 3 As shown, the bottom end of the anchor borehole is at the same depth as the bottom end of the steel casing, which further plays a reinforcement role and prevents the cave from collapsing when the shield tunnel passes through.

[0038] In the present invention, a load sensor is also installed on the anchor rod 6 to monitor the stress state of the anchor rod 6 in real time and feed the data back to the monitoring system. Through monitoring, the stress anomaly of the anchoring system can be discovered in time to ensure construction safety. A flexible connection cushion layer is also provided between the steel frame support frame 7 and the ground to absorb stress fluctuations caused by geological deformation, reduce the impact of construction disturbances on surrounding geology, and improve the stability and deformation resistance of the overall system.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating a karst cave when a shield tunnel passes through a karst cave, characterized in that: The following steps are involved: S1. Locate the cave; S2. Arrange grouting drilling points on the ground, and the drilling depth reaches the top of the cave above; S3. Install a primary steel casing in the borehole; S4, grouting into the upper cave through the first-level steel casing; S5. After grouting to the top of the primary steel casing, drill again and grout after drilling, repeating several times; S6. Weld the secondary steel casing on the top of the primary steel casing, and lower the primary steel casing and the secondary steel casing; S7, continue drilling through the primary steel casing and the secondary steel casing to drill through the cave below; S8, injecting grout into the cave below through the primary steel casing and the secondary steel casing; S9. After grouting to the top of the primary steel casing, drill again and grout after drilling, repeating several times; S10. Repeat steps S6-S9 until the calibration depth is reached.

2. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 1, characterized in that: In step S1, geological radar, three-dimensional seismic survey instrument and ultrasonic reflectometer are used to conduct geological survey on the construction area of ​​the shield tunnel line to determine the location, number, size and shape of the karst caves.

3. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 2, characterized in that: According to the characteristics of the caves, they are divided into fully filled caves, semi-filled caves and cavity caves. The fully filled caves are filled with cement-water glass double liquid slurry, the semi-filled caves are filled with bentonite-cement slurry, and the cavity caves are filled with polyurethane slurry.

4. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 1, characterized in that: The method also includes step S301: leading the groundwater in the cave to a water reservoir on the ground through a primary steel casing and a water diversion pipe.

5. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 1, characterized in that: The method further includes step S201: arranging anchor drilling points on the ground, embedding one end of the anchor rod into the rock formation through the drilling hole, and connecting the other end of the anchor rod to a steel frame support frame, wherein the steel frame support frame is fixed on the ground.

6. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 5, characterized in that: In step S201, a load sensor is also installed on the anchor rod to monitor the stress state of the anchor rod in real time and feed the data back to the monitoring system.

7. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 5, characterized in that: In step S201, a flexible connection cushion layer is provided between the steel frame support frame and the ground to absorb stress fluctuations caused by geological deformation.

8. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 5, characterized in that: The bottom end of the anchoring borehole is as deep as the bottom end of the steel casing.

9. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 1, characterized in that: A flange is detachably mounted on the top of the steel casing.

10. The method for treating a karst cave when a shield tunnel passes through a karst cave according to claim 5, characterized in that: Before step S4, the method further includes: injecting anti-seepage slurry into the surrounding area of ​​the cave through drilling holes to form a continuous anti-seepage curtain.

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