Supporting method for safe construction of large-section blocking wall of tunneling by excavation

Abstract

This invention discloses a support method for the safe construction of a large-section sealing wall in a mined tunnel, comprising: firstly, constructing the main tunnel using a combination of double-side-wall pilot tunnels and CRD (Continuous Relief Drilling) to the sealing wall location, then installing I1-type steel arch frames, I3-type steel, and prestressed anchor rods. After the initial support ring is formed in the main tunnel section, the I3-type steel support within the section of the smaller tunnel opening is removed, and then I2-type steel arch frames are installed. The I1-type steel arch frames, I2-type steel arch frames, and I3-type steel are connected to form an I-beam frame, and prestressed anchor rods are used to fix the I-beam frame within the initial support of the sealing wall, forming a new type of sealing wall section support mode. After the small tunnel opening is excavated and initially supported, and the surrounding rock of the small tunnel is stabilized, prestress is applied to the prestressed anchor rods of the sealing wall, waterproof membrane is laid, and secondary lining is poured. This invention improves the sealing wall structure and its resistance to lateral pressure, ensures the stability of the large-section sealing wall structure, and features a mature, simple, and highly versatile construction process.

Description

Technical Field

[0001] This invention belongs to the field of tunnel sealing wall construction technology, and in particular, it is a support method for safe construction of large-section sealing walls in mined tunnels. Background Technology

[0002] End capping walls are common lining structures in highway tunnels. With the continuous improvement of my country's highway transportation system, highway tunnels are trending towards more complex structures, larger cross-sections, and greater burial depths. The proportion of large-section end capping walls in future tunnel construction is increasing. Large-section end capping walls generally appear in the following situations: 1) at the intersection of a branch tunnel and a main tunnel; 2) at the intersection of a large-section tunnel and a small-section tunnel; 3) at the intersection of tunnels with significant differences in cross-sectional shape; 4) in large-section chambers within tunnels (e.g., end capping walls for underground ventilation room chambers in extra-long tunnels).

[0003] The sealing wall is located at the junction of different tunnel sections. Its vertical structure and complex stress distribution make it vulnerable. Conventional sealing walls in tunnels have small cross-sections, resulting in low lateral pressure from the undisturbed soil and simple structures. Standard anchoring, meshing, and shotcreting methods are sufficient to maintain the stability of the surrounding rock. However, large-section sealing walls exert significant lateral pressure from the undisturbed soil. Especially in this part of the tunnel, the stress distribution is complex, and conventional anchoring, meshing, and shotcreting methods are insufficient to maintain the stability of the surrounding rock. If the support structure of large-section sealing walls is not properly managed, their stability cannot be guaranteed, compromising construction safety and the overall stability of the tunnel structure. Therefore, it is urgent to develop a practical and effective support method for the safe construction of large-section sealing walls. Summary of the Invention

[0004] The purpose of this invention is to address the technical challenge of maintaining the stability of the surrounding rock of large-section sealing walls using conventional sealing wall construction methods in existing technologies, and to provide a support method for the safe construction of large-section sealing walls in mined tunnels.

[0005] The technical solution for achieving the objective of this invention is: a support method for the safe construction of a large-section sealing wall in a mined tunnel, the method comprising the following steps:

[0006] Step 1: The main tunnel is constructed using a combination of double-sided pilot tunnel and CRD (cross-diaphragm wall method).

[0007] Step 2: When construction reaches the sealing wall, install I1 type steel arch frame, I3 type steel, prestressed anchor rods or face anchor rods;

[0008] Step 3: After the initial support ring is formed on the main tunnel section, the I3 steel support within the section of the small tunnel is removed, and then the I2 steel arch frame is constructed. The I1 steel arch frame, the I2 steel arch frame and the I3 steel are connected to form an I-beam frame.

[0009] Step 4: Excavation and initial support of the tunnel opening. After the surrounding rock of the opening is stable, prestress is applied to the prestressed anchor rods of the sealing wall.

[0010] Step 5: Lay waterproof membrane and pour secondary tunnel lining.

[0011] Furthermore, the I1 type steel arch frame mentioned in step 2 is located within the initial support structure of the tunnel main opening and simultaneously within the initial support structure of the sealing wall, thus serving the initial support functions of both the tunnel main opening and the sealing wall.

[0012] Furthermore, one end of the I3 steel described in step 2 is connected to the I1 steel arch frame, and the I3 steel is fixed in the initial support of the sealing wall by prestressed anchor rods, so that it becomes a tight integral load-bearing structure.

[0013] Furthermore, the prestressed anchor rods are arranged in a quincunx pattern, with a length of not less than 5m and a spacing of 0.5m to 1m.

[0014] Furthermore, in step 2, anchor bolts are installed at the tunnel face within the small opening area, which improves the safety of the sealing wall construction and also facilitates the subsequent removal of the I3 steel support.

[0015] Furthermore, the I2 type steel arch frame mentioned in step 3 is located within the initial support structure of the tunnel opening and simultaneously within the initial support structure of the sealing wall, thus taking into account both the initial support functions of the tunnel opening and the sealing wall.

[0016] Furthermore, in step 3, the I3 type steel support within the cross-section of the tunnel opening is removed, and one end of the I3 type steel is connected to the I2 type steel arch frame to form a new type of hyperbolic laminated I-beam frame structure.

[0017] Furthermore, in step 4, the prestressed anchor rod is subjected to a prestress of not less than 100kN.

[0018] Compared with the prior art, the significant advantages of this invention are:

[0019] 1) A novel support mode for the sealing wall section is proposed. The sealing wall is supported in a timely manner during the construction of the tunnel's large opening, which improves the safety of tunnel construction. At the same time, the use of prestressed anchor rods to fix the I-beam frame in the initial support of the sealing wall improves the lateral pressure resistance of the sealing wall structure and ensures the stability of the large-section sealing wall structure.

[0020] 2) The construction process is mature and simple, and the materials are all commonly used in tunnel construction. Moreover, this construction method is applicable to sealing walls of different large sections and has universality.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the support method for safe construction of a large-section sealing wall in a mined tunnel according to an embodiment of the present invention.

[0023] Figure 2 The above embodiment describes the excavation sequence for the tunnel main opening construction in step 1.

[0024] Figure 3 This is a schematic diagram of the initial support ring formation and subsequent sealing wall support for the tunnel main section in step 2 of the above embodiments.

[0025] Figure 4 This is a schematic diagram of the I3 steel section that needs to be removed in step 3 of the above embodiment.

[0026] Figure 5 This is a schematic diagram of the I-beam steel frame for the large-section sealing wall in step 3 of the above embodiments.

[0027] Figure 6 This is a top view of the large-section sealing wall in the above embodiment.

[0028] Figure 7 This is a side view of the large-section sealing wall in the above embodiment.

[0029] Figure 8 This is a schematic diagram of the connection between the prestressed anchor rod and the I3 type steel in the above embodiment.

[0030] Figure 9 This is a schematic diagram of the connection between the I3 type steel and the I1 type steel arch frame and the I2 type steel arch frame in the above embodiment.

[0031] The attached diagram shows the markings and corresponding component names:

[0032] A—A pilot tunnel, B—B pilot tunnel, C—C pilot tunnel, D—D pilot tunnel, E—E pilot tunnel, F—F pilot tunnel, G—G pilot tunnel, H—H pilot tunnel, Ⅰ—Ⅰ pilot tunnel, J—J pilot tunnel, K—temporary support, 1—I1 type steel arch frame, 2—I2 type steel arch frame, 3—I3 type steel, 4—prestressed anchor bolt, 5—face anchor bolt, 6—pad plate and high-strength bolt, 7—waterproof membrane, 8—pad plate. Detailed Implementation

[0033] To make the technical solution of this invention clearer, this invention takes the Qizishan Tunnel project of the Yangtze River Road South Extension Project as an example, and the invention will be further explained below with reference to the accompanying drawings. It should be understood that the embodiments described herein are only some embodiments of this invention, and are only used to explain this invention, and are not limited to this invention.

[0034] Combination Figure 1 , Figure 6 , Figure 7 This invention proposes a support method for the safe construction of a large-section sealing wall in a mined tunnel, comprising the following steps:

[0035] (1) The main tunnel is constructed using a combination of double-sided pilot tunnels and CRD (Construction Reduction) method.

[0036] (2) When construction reaches the sealing wall, construct I1 type steel arch frame 1, I3 type steel 3, prestressed anchor rod 4 or face anchor rod 5;

[0037] (3) After the initial support of the tunnel main section is formed into a ring, the I3 type steel 3 support within the tunnel small section is removed, and then the I2 type steel arch frame 2 is constructed. The I1 type steel arch frame 1, the I2 type steel arch frame 2 and the I3 type steel 3 are connected to form an I-beam frame.

[0038] (4) Excavation and initial support of the tunnel small hole: After the surrounding rock of the small hole is stable, the prestressed anchor rod 4 of the sealing wall is prestressed.

[0039] (5) Lay waterproof membrane 7 and pour secondary tunnel lining.

[0040] In step (1), combined with Figure 2 The main tunnel is constructed using a combination of double-sided pilot tunnels and CRD (cross-diaphragm wall method). The excavation sequence is A(A), B(B), C(C), D(D), E(E), F(F), G(G), H(H), I(I), J(J).

[0041] In step (2), combined with Figure 3 At each section of the excavation reaching the sealing wall, first sprayed concrete is used to seal the surrounding rock, then I1 type steel arch frame 1 is constructed, followed by I3 type steel 3. The I3 type steel 3 is arranged vertically with its web facing the working face. The ends of the I3 type steel 3 and the I1 type steel arch frame 1 are connected by pads and high-strength bolts 6. At the same time, prestressed anchor rods 4 are constructed. The prestressed anchor rods 4 pass through the reserved holes of the I3 type steel 3 and are fixed in the initial support structure of the sealing wall by pads 8. The prestressed anchor rods 4 are arranged in a quincunx pattern, with a length of not less than 5m and a spacing of 0.5m to 1m.

[0042] In step (2), the I1 type steel arch frame 1 is located within the initial support of the tunnel main opening and simultaneously within the initial support of the sealing wall, thus taking into account both the initial support functions of the tunnel main opening and the sealing wall.

[0043] In step (2), combined with Figure 9 One end of the I3-type steel 3 is connected to the I1-type steel arch frame 1, and the I3-type steel 3 is fixed in the initial support structure of the sealing wall using prestressed anchor rods 4. Figure 8 As shown, this ensures a tight, integral load-bearing structure. The prestressed anchor bolts 4 are arranged in a staggered pattern, with a length of not less than 5m and a spacing of 0.5m to 1m.

[0044] In step (2), anchor bolts 5 are installed at the tunnel face within the small opening area, which improves the safety of the sealing wall construction and also facilitates the removal of the I3 steel 3 support later.

[0045] In step (3), the I2 type steel arch frame 2 is located within the initial support of the tunnel opening and the initial support of the sealing wall, thus taking into account both the initial support functions of the tunnel opening and the sealing wall.

[0046] In step (3), combined with Figure 4 and Figure 5 The I3 type steel support within the cross-section of the small tunnel opening was removed, combined with... Figure 9 One end of the I3 steel 3 is connected to the arch frame of the I2 steel 2, forming a new type of hyperbolic laminated I-beam frame structure.

[0047] In step (4), the prestressed anchor rod 4 is subjected to a prestress of not less than 100kN.

[0048] This invention proposes a novel cross-sectional support mode for sealing walls and provides clear supporting construction methods. Timely support of the sealing wall during the construction of large tunnel openings improves the safety of tunnel construction. At the same time, the use of prestressed anchor rods to fix the I-beam frame within the initial support of the sealing wall improves the lateral pressure resistance of the sealing wall structure and ensures the stability of the large-section sealing wall structure.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A supporting method for safe construction of a large-section blocking wall of a tunnel excavated by a method, characterized in that, The method includes the following steps: Step 1: The main tunnel is constructed using a combination of double-side-wall pilot tunnels and cross-diaphragm wall CRD method. Step 2: When construction reaches the sealing wall, install I1 type steel arch frame, I3 type steel, prestressed anchor rods, and face anchor rods; Step 3: After the initial support ring is formed on the main tunnel section, the I3 steel support within the section of the small tunnel is removed, and then the I2 steel arch frame is constructed. The I1 steel arch frame, the I2 steel arch frame and the I3 steel are connected to form an I-beam frame. Step 4: Excavation and initial support of the tunnel opening. After the surrounding rock of the opening is stable, prestress is applied to the prestressed anchor rods of the sealing wall. Step 5: Lay waterproof membrane and pour secondary tunnel lining; The I1 type steel arch frame mentioned in step 2 is located within the initial support structure of the tunnel main opening and also within the initial support structure of the sealing wall. In step 2, one end of the I3 steel is connected to the I1 steel arch frame, and the I3 steel is fixed in the initial support of the sealing wall by prestressed anchor rods; In step 2, anchor bolts are installed at the tunnel face within the area of ​​the small opening in the tunnel; The I2 type steel arch frame mentioned in step 3 is located within the initial support structure of the tunnel opening and also within the initial support structure of the sealing wall. In step 3, the I3 type steel support within the cross-section of the tunnel opening is removed, and the other end of the I3 type steel is connected to the I2 type steel arch frame. The I3 type steel, the I1 type steel arch frame and the I2 type steel arch frame form a hyperbolic laminated I-beam frame.

2. The support method for safe construction of a large-section sealing wall in a mined tunnel according to claim 1, characterized in that, The prestressed anchors are arranged in a quincunx pattern, with a length of not less than 5m and a spacing of 0.5m to 1m.

3. The support method for safe construction of a large-section sealing wall in a mined tunnel according to claim 1, characterized in that, In step 4, the prestressed anchor rod is subjected to a prestress of not less than 100kN.

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