A boulder detection and processing method for shield tunneling under old building area

Abstract

The present application relates to the technical field of shield construction, and particularly relates to a boulder detection and processing method for shield tunneling under old building area, which comprises the following steps: S1, CT scanning detection is performed on the boulder under the building to find out the spatial position and size of the boulder; S2, according to the CT scanning result, drilling hole positions for the boulder are arranged on the ground on both sides of the building; S3, the boulder is drilled through the drilling equipment and the drilling hole positions; S4, after the drilling is completed, a PVC pipe is inserted into the boulder; S5, the surrounding of the shield tunnel is grouted and pre-reinforced through the PVC pipe; and S6, the drilled hole after grouting is sealed and cleaned. The method not only ensures that the boulder hindering the construction can be cleaned during the shield tunnel construction, and the building above the shield tunnel is not damaged, but also reduces the construction cost, shortens the construction period, and improves the construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring machine (TBM) construction technology, and in particular to a method for detecting, processing, and constructing tunnel boring machines (TBMs) under isolated boulders in areas with old buildings. Background Technology

[0002] With the acceleration of urbanization in China, the increasing urban population is putting growing pressure on urban transportation. However, urbanization should not be constrained by traffic congestion; therefore, underground transportation, in contrast to traditional surface transportation, has become a new channel for alleviating urban traffic pressure. Subway transportation is a green project and aligns with China's sustainable development strategy, and it is gradually being promoted in large and medium-sized cities. Subway construction involves shield tunneling. Due to the complex surrounding architecture in different cities, shield tunnels often pass through buildings, requiring the tunnel boring machine to traverse complex geological formations beneath these structures, especially strata containing boulders and characterized by soft upper layers and hard lower layers.

[0003] For strata containing boulders that are soft on top and hard underneath, current conventional methods in tunnel boring machine (TBM) construction typically involve traditional mining methods such as TBM rock breaking, manual rock breaking, static blasting inside the tunnel, and explosive blasting. However, when the boulders are located beneath old buildings, these methods can cause significant ground disturbance, jeopardizing the safety of the buildings. Using traditional mining methods requires the demolition of old buildings, which presents a series of problems including high costs, significant delays in the demolition process, and cumbersome demolition procedures. Therefore, a solution is urgently needed.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is the closest prior art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for detecting, processing and constructing isolated rocks when shield tunnels pass under old residential areas. This method not only ensures that isolated rocks that obstruct construction can be cleared during shield tunnel construction, but also does not damage the buildings above the shield tunnel. At the same time, it reduces construction costs, shortens the construction period, and improves the construction efficiency of the project.

[0006] To achieve the aforementioned objective, the technical solution of the present invention is implemented as follows: A method for detecting, processing, and constructing boulders when a shield tunnel passes under an area with old buildings is provided, characterized by the following steps:

[0007] S1. CT scans are performed on the isolated rock located below the building and within the cross-section of the shield tunnel construction path to determine its spatial location and size.

[0008] S2, Based on the CT scan results, drill holes for the boulders are arranged on the ground around the building.

[0009] S3, drilling holes in the boulder using drilling equipment and drilling positions, and pre-splitting the boulder;

[0010] S4, drilling is performed on the soil around the cross-section of the shield tunnel construction path using drilling equipment;

[0011] S5, After drilling is complete, insert the PVC pipe into the drill hole;

[0012] S6 uses PVC pipes to grout and pre-reinforce the boulders and the soil around the cross-section of the shield tunnel construction path, forming a grout-reinforced body inside and outside the cross-section of the shield tunnel construction path.

[0013] S7, seal and clean the drilled holes after grouting is completed.

[0014] Preferably, the CT scan detection uses the fan-shaped penetration method, combined with an inversion algorithm to obtain the spatial location and morphological characteristics of the isolated rock.

[0015] Preferably, in step S3, the method of drilling holes in the boulder is to drill holes obliquely and densely on the surface of the boulder, and the spacing between each hole on the boulder is 600*600mm, and each hole is distributed in a quincunx pattern along the surface of the boulder.

[0016] Preferably, the grouting is a two-component grout composed of cement grout and water glass grout, and a backward grouting method is adopted, with a pressure of 2.5 MPa and a drill pitch of 1 m. The longitudinal range of the grouting reinforcement is at least twice the diameter of the boulder C, and the transverse reinforcement range is the cross section of the shield tunnel 10 construction path and the soil within a 3 m radius around it.

[0017] Preferably, the volume ratio of cement slurry to water glass slurry in the grouting is 1:1, and the volume ratio of cement to water in the cement slurry is 1:0.8, and the volume ratio of water glass to water in the water glass slurry is 1:1.

[0018] Preferably, the borehole on the boulder is a through hole and extends into the cross-section of the shield tunnel construction path.

[0019] Preferably, the boreholes on the soil around the cross-section of the shield tunnel construction path are evenly distributed.

[0020] Preferably, the PVC pipe is processed into a grouting perforated pipe with a diameter of 30mm.

[0021] Preferably, the center of the PVC pipe coincides with the center of the drill hole, and the length of the PVC pipe is 0.3m longer than the depth of the drill hole.

[0022] Preferably, the PVC pipe end is fitted with a protective cap.

[0023] The beneficial effects of this invention are reflected in:

[0024] (1) This invention pre-cracks boulders by drilling holes in the ground, and then injects grout into the holes in the boulders and the soil surrounding the tunnel construction path. The injected grout seeps out along the pre-cracked cracks in the boulders and merges with the grout in the soil surrounding the tunnel construction path. The solidified grout then fixes the cracked boulders. This makes the boulders and soil layers that were originally scattered on the tunnel construction path form a whole, that is, a grout-reinforced body on the tunnel construction path. When the tunnel boring machine (TBM) constructs the tunnel on the grout-reinforced body, the TBM will only excavate the tunnel within the grout-reinforced body, and will not cause the boulders and soil layers above the tunnel to collapse due to the boulders falling off. This method of treating boulders below buildings not only does not affect the buildings above the tunnel, but also speeds up the tunnel construction progress and effectively shortens the construction period.

[0025] (2) The method of the present invention can minimize the impact of shield tunneling and boulder treatment on the house when dealing with isolated boulders located under old houses, thus ensuring the safety of the house.

[0026] (3) The present invention uses ground drilling to break up large boulders, which reduces the wear of the boulders on the cutting tools during shield tunneling, avoids the risk of sudden changes in shield attitude caused by boulders, and improves the safety of construction.

[0027] (4) The grouting slurry used in this invention is a two-component slurry composed of cement slurry and water glass slurry. Both are environmentally friendly materials that will not pollute the soil and effectively reduce the impact on the surrounding environment, thus achieving green construction.

[0028] (5) The method provided by the present invention ensures that the center of the PVC pipe coincides with the center of the borehole, so that the PVC pipe can be fully inserted into the borehole, and the grouting can reach the location of the boulder smoothly. In actual construction, the length of the PVC pipe is 0.3m longer than the depth of the borehole to avoid soil or debris around the borehole from falling into the PVC pipe and causing pipe blockage.

[0029] (6) The method provided by this invention involves drilling holes obliquely and densely on the surface of the boulder. This drilling method ensures successful drilling of the boulder located directly below the building from the side of the building, reducing construction difficulty. Furthermore, the spacing between the drill holes on the boulder is 600*600mm, creating a dense network that allows for pre-fracture and breaks down larger boulders into smaller pieces. The drill holes are distributed in a quincunx pattern along the surface of the boulder, resulting in more uniform pre-fracture and facilitating better connection and encapsulation of the grout during subsequent grouting. Simultaneously, the resulting grout-reinforced structure exhibits greater internal stability. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method of the present invention;

[0031] Figure 2 This is a schematic diagram showing the locations of the boulder, shield tunnel, and building in this invention.

[0032] Figure 3 This is a schematic diagram of the grouting construction process of the present invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] A. Building; B. Ground; C. Isolated rock;

[0035] 10. Shield tunnel; 20. PVC pipe; 30. Grouting reinforcement. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] See Figures 1 to 3 As shown:

[0039] This invention provides a method for detecting and handling isolated boulders when tunneling under old residential areas using a shield tunneling machine. The method includes the following steps:

[0040] S1. CT scan detection is performed on boulder C located below building A and within the cross-section of the shield tunnel 10 construction path to determine the spatial location and size of boulder C.

[0041] CT scans employ a single-shot, multi-receiver fan-shaped penetration method, generating a dense network of intersecting rays within the measured area through point-by-point excitation. During CT scan data processing, the measured area is divided into several regular imaging units based on the sparseness of the rays and the imaging precision. At this point, the geological medium of each imaging unit can be considered homogeneous, and the wave velocity uniform. Then, an inversion algorithm can be used to accurately obtain the spatial location and morphological characteristics of the isolated boulder C.

[0042] S2. Based on the CT scan results, drill holes for the boulder C are arranged on the ground B around building A.

[0043] S3. Drill a hole in boulder C using drilling equipment and at the designated hole location. A geological drilling rig with a full-face drill bit is used for drilling. The drill bit diameter should be larger than the designed borehole diameter. The hole should not be too large, nor smaller than the designed borehole diameter, to ensure that the PVC pipe 20 can be inserted smoothly.

[0044] During drilling operations, the surface of boulder C was treated with a dense, oblique drilling method, with each hole spaced 600*600mm and arranged in a quincunx pattern. This method pre-fractured the boulder C and bedrock within the construction path of the shield tunnel 10, reducing the integrity of boulder C and bedrock.

[0045] The drilling area for boulder C and bedrock is within 0.95m on both sides of the construction path of shield tunnel 10. The borehole will penetrate boulder C and extend into the cross-section of the construction path of shield tunnel 10.

[0046] S4 involves drilling holes at equal intervals in the soil around the construction path section of shield tunnel 10 using drilling equipment.

[0047] S5. After drilling is completed, insert PVC pipe 20 into the borehole. PVC pipe 20 is a grouting pipe with a diameter of 30mm, and is pre-processed into a grouting perforated pipe. The installation of PVC pipe 20 should be carried out immediately after drilling is completed to prevent the borehole from collapsing due to a long interval, which would make it impossible to insert PVC pipe 20.

[0048] In addition, when lowering the PVC pipe 20 along the borehole, a joint is used for connection. Throughout the installation process, the center of the PVC pipe 20 should be aligned with the center of the borehole to ensure that the PVC pipe 20 can be lowered to the bottom of the borehole. Simultaneously, the length of the PVC pipe 20 is determined based on the actual borehole depth. The PVC pipe 20 must be installed 0.3m above the ground level; therefore, the actual installation length of the PVC pipe 20 is the borehole depth plus 0.3m. A protective cap is used at the pipe opening to prevent debris from entering the PVC pipe 20 before grouting.

[0049] S6, through PVC pipe 20, grouting is used to pre-reinforce the isolated rock C and the soil around the construction path section of shield tunnel 10, forming a grouting reinforced body 30 inside and outside the construction path section of shield tunnel 10.

[0050] The grouting scope includes pre-reinforcing the soil around the waist of the cross-section of the shield tunnel 10 construction path to fix the position of the broken boulder C. At the same time, the soil at the arch of the cross-section of the shield tunnel 10 construction path is also pre-reinforcing by grouting, which can reduce the disturbance to the strata when the shield machine breaks the boulder C during actual construction.

[0051] Grouting uses a two-component grout mixture of cement grout and water glass grout, and employs a backward grouting method. When the pressure reaches 2.5 MPa, the drill is lifted 1 m. The longitudinal grouting range is at least twice the diameter of boulder C, and the transverse reinforcement range is the cross-section of the shield tunnel 10 construction path and its outer 3 m range.

[0052] The mixing ratios of cement grout and water glass grout used for grouting reinforcement are as follows:

[0053] Liquid A (mass ratio) Solution B (volume ratio) Liquid A: Liquid B Units of measurement Cement:water = 1:0.8 Water glass:water = 1:1 1:1 m3

[0054] S7, seal and clean the drilled holes after grouting is completed.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting, handling, and constructing isolated boulders when tunneling under old residential areas using a shield tunneling machine, characterized in that... The method includes the following steps: S1, CT scan detection is performed on the isolated rock (C) located below the building (A) and within the cross section of the shield tunnel (10) construction path to determine the spatial location and size of the isolated rock (C); S2, Based on the CT scan results, drill holes for the boulder (C) are arranged on the ground (B) around the building (A); S3, Drill holes in boulder (C) using drilling equipment and drilling positions, and perform pre-splitting treatment on boulder (C); S4, Drill holes in the soil around the construction path section of the shield tunnel (10) using drilling equipment; S5, After drilling is completed, insert the PVC pipe (20) into the hole; S6, grouting pre-reinforcement is carried out on the isolated rock (C) and the soil around the cross section of the shield tunnel (10) construction path through PVC pipe (20), forming a grouting reinforced body (30) inside and outside the cross section of the shield tunnel (10) construction path. S7, seal and clean the drilled holes after grouting; The CT scan detection uses the fan-shaped penetration method, combined with the inversion algorithm to obtain the spatial location and morphological characteristics of the isolated rock (C); In step S3, the method of drilling holes in the boulder (C) is to drill holes obliquely and densely on the surface of the boulder (C), and the spacing between each hole on the boulder (C) is 600*600mm. The holes are distributed in a quincunx pattern along the surface of the boulder (C). The grouting is a two-component grouting of cement grout and water glass grout, and a backward grouting method is adopted. The pressure reaches 2.5MPa, the drill is lifted 1m, and the longitudinal range of grouting reinforcement is at least twice the diameter of boulder C. The transverse reinforcement range is the cross section of the shield tunnel 10 construction path and the soil within 3m around it. The volume ratio of cement slurry to water glass slurry in the grouting is 1:1, and the volume ratio of cement to water in the cement slurry is 1:0.8, while the volume ratio of water glass to water in the water glass slurry is 1:

1. The borehole on the boulder (C) is a through hole and extends into the cross section of the shield tunnel (10) construction path.

2. The method for detecting, processing, and constructing isolated boulders under a shield tunneling project in an area with old buildings, as described in claim 1, is characterized in that; The boreholes are evenly distributed on the soil around the construction path section of the shield tunnel (10).

3. The method for detecting, processing, and constructing isolated boulders under a shield tunneling project in an area with old buildings, as described in claim 2, is characterized in that; The PVC pipe (20) is processed into a grouting pipe with a diameter of 30mm.

4. The method for detecting, processing, and constructing isolated boulders under a shield tunneling area of ​​old residential buildings according to claim 3, characterized in that; The center of the PVC pipe (20) coincides with the center of the borehole, and the length of the PVC pipe (20) is 0.3m longer than the depth of the borehole.

5. The method for detecting, processing, and constructing isolated boulders under a shield tunneling area of ​​old residential buildings according to claim 4, characterized in that; The PVC pipe (20) has a protective cap on its opening.

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