Karst treatment method for shield tunnel underneath passing building

Abstract

The invention discloses a karst treatment method for a shield tunnel underneath passing building. The construction method comprises the following steps that a working vertical shaft is constructed outside the influence range of the existing building, and the working vertical shaft is sequentially and gradually excavated and implemented from the ground to the underground; in the working vertical shaft, a plurality of axial drill holes arranged in a matrix mode are constructed in the underground direction of the existing building for grouting, and underground developed karst of the existing building is grouted and tamped through the axial drill holes; backfilling the working shaft to restore the original appearance of the ground; and a shield tunnel penetrates through the underground of the existing building and is positioned in the grouting parts of the plurality of axial drill holes. The method is suitable for pretreatment of shield construction, the actual operability is high, on the premise that safe construction of a shield tunnel is guaranteed, ground drilling exploration, ground karst cave treatment and other work do not need to be conducted within the influence range of a building, the demolition problem is avoided, the construction technology is simplified, the construction period is shortened, and the engineering cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of rail transit engineering, and in particular to a karst treatment method for a shield tunnel passing under a building. Background Art

[0002] With the development of urban transportation, line planning is becoming increasingly complex and land use issues are becoming increasingly tense. Due to historical issues left over from urban planning and urban construction, it is inevitable for rail transit to pass under existing buildings. However, due to geological problems, some of the buildings under the rail transit are located in karst development areas. If the karst is not treated, the risk of shield tunneling is huge.

[0003] According to conventional practice, if a shield tunnel passes under a building (the building is located in a karst development area), the existing buildings on the ground need to be demolished. Only after the demolition is completed will the conditions for ground karst exploration and treatment be met, and only after the karst treatment is completed can the safety of the shield construction be ensured.

[0004] The Chinese patent "Shield Tunnel Construction Method for Karst Treatment in Cave" (application publication number CN117646630A) adopts the method of excavating a temporary shaft at a site far away from ground buildings, then excavating a horizontally arranged pilot tunnel inside the temporary shaft, and filling the cave by radial grouting reinforcement around the pilot tunnel. However, this construction method has the following problems:

[0005] First, the excavation of pilot tunnels is risky and prolongs the construction period, increasing the project cost;

[0006] Second, the operating space for radial grouting in the pilot tunnel is small and the actual operability is poor;

[0007] Third, after filling all the caves, the guide tunnel needs to be backfilled with low-grade concrete, and the strength of the backfill body must meet the requirements of later shield excavation, which once again extends the construction period and increases the project cost. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention proposes a karst treatment method for a shield tunnel passing under a building. Under the premise of ensuring the safe construction of the shield tunnel, it not only avoids the demolition problem but also simplifies the construction process, shortens the construction period and reduces the project cost.

[0009] In order to achieve the above-mentioned object, the present invention is designed to provide a karst treatment method for a shield tunnel passing under a building, which is particularly characterized in that it comprises the following steps:

[0010] S1) constructing a working shaft outside the influence range of the existing building, wherein the working shaft is excavated step by step from the ground to the underground;

[0011] S2) in the working shaft, a plurality of axial drilling grouting lines arranged in a matrix manner are applied toward the underground direction of the existing building, and each axial drilling grouting line extends along the axial direction of the shield tunnel to be constructed later, and the area where the plurality of axial drilling grouting lines are located covers the stratum of the shield tunnel to be constructed later;

[0012] Use axial drilling to fill the developed karst underground of existing buildings with grouting;

[0013] S3) After the grouting is completed, the working shaft is backfilled to restore the original appearance of the ground;

[0014] S4) passing a shield tunnel under an existing building and inside a plurality of axial bored holes and grouting lines, wherein the shield tunnel comprises a left shield tunnel line and a right shield tunnel line.

[0015] Further, in S1), the implementation steps of the working shaft include:

[0016] S11) First, a shaft locking ring beam is implemented around the working shaft ground;

[0017] S12) excavating and constructing the shaft wall section by section along the shaft locking ring beam;

[0018] S13) When excavation reaches the bottom of the working shaft, the bottom is sealed with shaft bottom concrete.

[0019] Furthermore, in S12), a shaft anchor is installed on the outer side of the shaft wall.

[0020] Furthermore, the shaft anchor rods are 2.0 to 4.0 m long and spaced 1 m*1 m apart.

[0021] Furthermore, in S12), the depth of the shaft wall of each section is 0.5 to 1.0 m.

[0022] Furthermore, in S1), the shaft wall profile is larger than the shield tunnel profile.

[0023] Furthermore, in S2), the axial drilling length is determined according to the size of the existing building.

[0024] Furthermore, in S2), the axial drilling spacing is determined according to the development characteristics of the underground karst of the existing buildings.

[0025] The advantages of the present invention are:

[0026] 1. The present invention is applicable to the case where the shield method is used to pass under existing buildings (such as passing through residential areas, single buildings with large floor space, other structures that are difficult to demolish, etc.), and there are karst geological disasters under the existing buildings. In order to ensure the safety of shield construction, the karst caves need to be treated before shield excavation to reduce the impact of tunnel construction on existing buildings on the ground;

[0027] 2. The working shaft in the present invention is located outside the building, which avoids the need to conduct ground drilling surveys and ground cave treatment within the influence range of the building, and avoids the problem of demolition;

[0028] 3. The present invention first constructs a working shaft outside the influence range of the existing building, then constructs axial drilling grouting in the working shaft toward the underground direction of the existing building, uses axial drilling to grout the cave, and finally performs normal shield tunneling inside the axial drilling grouting. Compared with the technical solution of shaft + pilot hole + radial grouting in the pilot hole in the Chinese patent (application publication number CN117646630A), the present invention has the following characteristics: first, it avoids the excavation and backfilling of the pilot hole, simplifies the construction process, shortens the construction period, and reduces the project cost; second, the radial grouting in the pilot hole is modified into axial drilling grouting in the working shaft, which improves the actual operability;

[0029] The karst treatment method for a shield tunnel under a building of the present invention is suitable for pre-treatment of shield construction and has strong practical operability. Under the premise of ensuring safe construction of the shield tunnel, it is not necessary to carry out ground drilling survey and ground karst cave treatment within the influence range of the building, thus avoiding the problem of demolition and simplifying the construction process, shortening the construction period and reducing the project cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flow chart of the present invention;

[0031] Figure 2 It is a plan view of the present invention applied to an embodiment;

[0032] Figure 3 A cross-sectional view of a working shaft in which the present invention is applied to an embodiment;

[0033] Figure 4 A longitudinal cross-sectional view of a working shaft in which the present invention is applied to an embodiment;

[0034] In the figure: existing buildings 1, working shaft 2, axial drilling and grouting 3, shield tunnel 4;

[0035] The existing building 1 includes: a first existing building 1-1 and a second existing building 1-2;

[0036] The working shaft 2 comprises: a shaft locking ring beam 2-1, a shaft wall 2-2, a shaft anchor rod 2-3, and a shaft bottom concrete 2-4;

[0037] The axial drilling grouting 3 includes: a first axial drilling grouting 3-1 and a second axial drilling grouting 3-2;

[0038] The shield tunnel 4 includes: a left shield tunnel line 4-1 and a right shield tunnel line 4-2. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0040] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the 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 invention.

[0041] The present invention is applicable to the case where the shield method is used to pass under existing buildings (such as passing under residential areas, single buildings with a large floor area, other structures that are difficult to demolish, etc.), and where there are karst geological disasters under the existing buildings, in order to ensure the safety of the shield construction, the karst caves need to be processed before the shield excavation to reduce the impact of the tunnel construction on the existing buildings on the ground.

[0042] like Figure 1 As shown, the present invention provides a karst treatment method for a shield tunnel passing under a building, comprising the following steps:

[0043] S1) A working shaft 2 is constructed outside the influence range of the existing building 1, and the working shaft 2 is excavated step by step from the ground to the underground.

[0044] In this embodiment, the building 1 includes a first existing building 1-1 and a second existing building 1-2. There are geological disasters such as karst development underground in the first existing building 1-1 and the second existing building 1-2.

[0045] Since the first existing building 1-1 and the second existing building 1-2 have been built, it is difficult to coordinate the demolition and it is impossible to conduct karst exploration and karst treatment on the surface, so the karst treatment method of the present invention is adopted. A working shaft 2 is set between the first existing building 1-1 and the second existing building 1-2.

[0046] To ensure construction safety, the working shaft 2 selects appropriate construction methods according to the ground conditions, adopts the inverted shaft wall method, or other enclosure structures. Since the working shaft 2 is located outside the building, it is avoided that ground drilling surveys and ground cave treatments are required within the influence range of the building, and the demolition problem is avoided.

[0047] Specifically, the implementation steps of the working shaft 2 in this embodiment include:

[0048] S11) First, a shaft locking ring beam 2-1 is installed around the ground of the working shaft 2.

[0049] S12) Excavating the shaft wall 2-2 in sections downwards along the shaft locking ring beam 2-1.

[0050] In order to comprehensively consider the construction accuracy and construction convenience, the profile of the shaft wall 2-2 is larger than the profile of the shield tunnel 4 described below. In this embodiment, the shaft wall 2-2 is made of grid steel reinforced shotcrete, and the concrete is C20 early strength and P6; the profile of the shaft wall 2-2 is 3m larger than the profile of the shield tunnel 4 described below.

[0051] Preferably, a shaft anchor 2-3 is applied on the outside of the shaft wall 2-2. Specifically, the shaft anchor 2-3 is 2.0-4.0 m long and has a spacing of 1 m*1 m. In this embodiment, the shaft anchor 2-3 is 3.5 m long.

[0052] According to the ground conditions, the depth of each section of the shaft wall 2-2 is 0.5-1.0 m. The next section of the shaft wall 2-2 can be excavated downwards only after the previous section of the shaft wall 2-2 reaches the designed strength.

[0053] S13) When excavating to the bottom of the working shaft 2, the bottom is sealed with shaft bottom concrete 2-4.

[0054] In addition, in this embodiment, in order to ensure the working space for horizontal drilling, the width of the working shaft 2 is 5.0m.

[0055] S2) in the working shaft 2, multiple axial drilling grouting lines 3 arranged in a matrix manner are applied toward the underground direction of the existing building 1, and each axial drilling grouting line 3 extends axially along the shield tunnel 4 to be constructed later, and the area where the multiple axial drilling grouting lines 3 are located covers the stratum of the shield tunnel 4 to be constructed later;

[0056] The developed karst under the existing building 1 is filled with grouting by axial drilling to ensure that there is no danger of head fall, loss of pressure, or falling into the cave during the shield tunneling.

[0057] After the working shaft 2 is completed, a construction platform is set up in the working shaft 2, and a small horizontal drill is used for drilling and grouting. Specifically, the axial drilling length is determined according to the size of the existing building 1, and the horizontal drilling length can reach 200m or even longer. In order to ensure the footage efficiency in limestone, an impact hammer is used for drilling. Specifically, the axial drilling spacing is determined according to the development characteristics of the underground karst of the existing building 1. In this embodiment, the axial drilling spacing is 2m*2m.

[0058] When grouting is used to fill developed karst caves using axial drilling, it is necessary not only to ensure that no dangerous situations such as head dive, loss of pressure, or falling into the karst cave will occur during the shield tunneling, but also to ensure the stability and safety of the surrounding rock of the tunnel during rail transit operations.

[0059] S3) After the grouting is completed, the working shaft 2 is backfilled to restore the original ground appearance. Preferably, clay is used to backfill and compact the working shaft 2.

[0060] S4) A shield tunnel 4 is passed under the existing building 1 and inside the multiple axial drilling and grouting lines 3, wherein the shield tunnel 4 includes a left shield tunnel line 4-1 and a right shield tunnel line 4-2.

[0061] The shield tunnel 4 can be constructed by normal underpass construction method.

[0062] The present invention first constructs a working shaft outside the influence range of the existing building, then constructs axial drilling grouting in the working shaft toward the underground direction of the existing building, uses axial drilling to grout the cave, and finally performs normal shield tunneling inside the axial drilling grouting. Compared with the technical solution of the Chinese patent (application publication number CN117646630A) using shaft + pilot hole + radial grouting in the pilot hole, the present invention avoids the excavation and backfilling of the pilot hole, simplifies the construction process, shortens the construction period, and reduces the project cost; at the same time, the radial grouting in the pilot hole is modified to axial drilling grouting in the working shaft, which improves the actual operability.

[0063] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A karst treatment method for a shield tunnel passing under a building, characterized in that: The steps include: S1) constructing a working shaft (2) outside the influence range of the existing building (1), wherein the working shaft (2) is excavated step by step from the ground to the underground; S2) in the working shaft (2), a plurality of axial drilling grouting lines (3) arranged in a matrix manner are applied toward the underground direction of the existing building (1), and each axial drilling grouting line (3) extends axially along the shield tunnel (4) to be constructed later, and the area where the plurality of axial drilling grouting lines (3) are located covers the stratum of the shield tunnel (4) to be constructed later; Using axial drilling to fill the developed karst underground of the existing building (1) with grouting; S3) After the grouting is completed, the working shaft (2) is backfilled to restore the original appearance of the ground; S4) A shield tunnel (4) is passed under an existing building (1) and inside a plurality of axial drilling and grouting lines (3), wherein the shield tunnel (4) comprises a left shield tunnel line (4-1) and a right shield tunnel line (4-2).

2. The karst treatment method for a shield tunnel passing under a building according to claim 1, characterized in that: In S1), the implementation steps of the working shaft (2) include: S11) First, a shaft locking ring beam (2-1) is installed around the ground of the working shaft (2); S12) excavating the shaft wall (2-2) in sections downwards along the shaft locking ring beam (2-1); S13) When the excavation reaches the bottom of the working shaft (2), the bottom is sealed with shaft bottom concrete (2-4).

3. The karst treatment method for a shield tunnel passing under a building according to claim 2, characterized in that: S12), a shaft anchor rod (2-3) is installed on the outer side of the shaft wall (2-2).

4. The karst treatment method for a shield tunnel passing under a building according to claim 3 is characterized by: The shaft anchor rods (2-3) are 2.0-4.0 m long and have a spacing of 1 m*1 m.

5. The karst treatment method for a shield tunnel passing under a building according to claim 4, characterized in that: In S12), the depth of each section of the shaft wall (2-2) is 0.5 to 1.0 m.

6. The karst treatment method for a shield tunnel passing under a building according to claim 5, characterized in that: S1), the profile of the shaft wall (2-2) is larger than the profile of the shield tunnel (4).

7. The karst treatment method for a shield tunnel passing under a building according to claim 1, characterized in that: In S2), the axial drilling length is determined according to the size of the existing building (1).

8. The karst treatment method for a shield tunnel passing under a building according to claim 7, characterized in that: In S2), the axial drilling spacing is determined according to the development characteristics of the underground karst of the existing building (1).

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