Excavation auxiliary device and excavation method suitable for underground space structure of soft rock stratum

Abstract

The invention belongs to the technical field of supporting, and discloses an excavation auxiliary device suitable for an underground space structure of a soft rock stratum, which is characterized by comprising a positioning mechanism, the middle part of the positioning mechanism is rotatably connected with a first supporting mechanism, and the top of the positioning mechanism is also provided with a positioning frame; and the middle part of the positioning frame is rotationally connected with a second supporting mechanism. According to the large-span extra-large-section underground space structure of the soft rock stratum, the whole section is divided into seven pilot tunnels to be excavated in a segmented mode, primary support is immediately constructed after excavation in the segmented pilot tunnels, the phenomenon that the vault settlement value is increased due to overlarge span and tunnel face stress relaxation is eliminated, the stability of the excavation face is enhanced, and the vault settlement value and the ground settlement value are effectively controlled; and when a pilot tunnel a and a pilot tunnel b are excavated, the two sets of devices are placed on the two side walls of the pilot tunnel in a staggered mode, the positioning mechanism 1 is fixed through anchor rods, preliminary supporting of the pilot tunnel a and the pilot tunnel b is achieved, and supporting is more convenient.

Description

Technical Field

[0001] This invention belongs to the field of support technology, specifically an excavation auxiliary device and excavation method applicable to underground space structures in soft rock strata. Background Technology

[0002] With the rapid development of urban transportation and modernization, urban rail transit has become an important means of transportation in urban construction. Urban tunnel transportation faces a complex and ever-changing environment with diverse geological conditions. Various traffic lines and underground pipelines intersect intricately, making the selection of appropriate construction methods particularly important in the construction of large-section tunnels. Generally, in cases with relatively good surrounding rock geology (Class I-III surrounding rock), the full-section method and bench method are preferred, provided that tunnel safety and quality are met. In cases with poor surrounding rock geology (Class IV-V surrounding rock), considering the safe construction of the tunnel, especially when the surrounding environment is complex, the double-sided wall pilot tunnel method and single-sided wall pilot tunnel method are preferred. Although the traditional single-sided wall pilot tunnel method has a simpler construction process, it is not suitable for the excavation of ultra-large-section tunnels in weak surrounding rock, as the surrounding rock is unstable and safety cannot be guaranteed.

[0003] When the surrounding rock of the tunnel section is mainly soft sandstone and sandy mudstone, the rock strata interface is affected by interlayer fissures and fissure water activity. The rock near this interface is relatively weak and broken, with poor self-stability, and is prone to collapse and rockfall. The double-sidewall pilot tunnel method is used for excavation. During construction, the distance between the tunnel faces of each pilot tunnel must be strictly less than the specified safe step distance, and each pilot tunnel must be immediately supported and closed after excavation. The construction operation is complex and cumbersome, with slow construction speed, long construction period, and high construction cost. Therefore, to address the above problems, an excavation auxiliary device and excavation method suitable for underground space structures in soft rock strata are proposed. Summary of the Invention

[0004] To address the problems mentioned in the background art regarding the use of the double-sided guide tunnel method for excavation, where the distance between the tunnel faces of each section must be strictly less than the specified safe step distance, and each section of the guide tunnel must be immediately supported and closed after excavation, resulting in complex and cumbersome construction operations, slow construction speed, long construction period, and high construction costs, this invention provides an excavation auxiliary device and excavation method suitable for underground space structures in soft rock strata.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an excavation auxiliary device suitable for underground space structures in soft rock strata, characterized in that: it includes a positioning mechanism, a first support mechanism is rotatably connected to the middle of the positioning mechanism, a positioning frame is also installed on the top of the positioning mechanism, and a second support mechanism is rotatably connected to the middle of the positioning frame; The first support mechanism includes a first support plate, a first support rod, a second support rod, and a third support rod. The first support plate is rotatably connected to a positioning mechanism. The first support rod is movably connected inside the first support plate. The second support rod is movably connected inside the first support rod. The third support rod is movably connected inside the second support rod.

[0006] Preferably, the positioning mechanism includes a positioning seat, a first anchor hole, and a connecting shaft. The first anchor hole is formed on the positioning seat, the connecting shaft is fixedly connected to the surface of the positioning seat, and the positioning seat is riveted to the tunnel through the first anchor hole.

[0007] Preferably, the first support mechanism further includes a second anchor hole, which is disposed on the surface of the first support plate, the first support rod, the second support rod, and the third support rod.

[0008] Preferably, the second support mechanism includes a second support plate and a movable hole, the second support plate being rotatably connected to the positioning frame, and the movable hole being opened on the side of the second support plate.

[0009] Preferably, both the first support plate and the second support plate are toothed, and the second support plate and the first support plate are interlocked.

[0010] This invention also provides an excavation method using an excavation auxiliary device suitable for underground space structures in soft rock strata, characterized by comprising the following steps: The large-span, extra-large cross-section is divided into nine regions, specifically three vertical layers (upper, middle, and lower) and three horizontal sections (left, middle, and right). Each region's width is 33%–38% of the total cross-section span, and its height is 30%–35% of the total cross-section height. The soil within the tunnel excavation section is further divided into seven sections: a, b, c, d, e, f, and g. Pilot tunnels are excavated in these sections, with the auxiliary excavation channel leading to the upper pilot tunnel of the main tunnel, completing the construction of the intersection system transition section. Specifically: section a is the upper bench of the left section; sections b, c, and d are the upper, middle, and lower benches of the right section; section e is the upper bench of the core rock pillar; section f includes the middle bench of the left section and the middle bench of the core rock pillar; and section g includes the lower bench of the left section and the lower bench of the core rock pillar. Step 1: First, excavate two pilot tunnels, section a and section b, and promptly implement temporary support. Section a is connected to the auxiliary excavation channel. Step 2: Excavate the pilot tunnel in section C and promptly implement initial support. Step 3: Excavate the pilot tunnel at section d and promptly implement initial support. Step 4: Excavate the pilot tunnel in section e and promptly implement temporary support; Step 5: Excavate the pilot tunnel of section f and promptly implement temporary support; Step Six: Excavate the pilot tunnel at section g and promptly implement temporary support; Step 7: Carry out the invert arch lining and arch wall lining of the mined tunnel in an orderly manner to complete the construction of the large-span and extra-large cross-section underground space structure.

[0011] Preferably, in step one, two pilot tunnels, section a and section b, on one side of the upper bench are excavated first. The excavation faces of the two pilot tunnels are staggered by a distance of not less than 15m before and after, and the upper benches of the left and right sides of the tunnel are connected one after the other. In step two, the pilot tunnel in section c is excavated. The length of the step excavation should not exceed 20m, and it can be dynamically adjusted according to the monitoring and measurement data.

[0012] Preferably, in step three, the pilot tunnel d is excavated to form a stepped excavation with the pilot tunnel c. The length of the stepped excavation does not exceed 20m, and can be dynamically adjusted according to the monitoring and measurement data during the process. In step four, the pilot tunnel of section e is excavated. The length of the step excavation shall not exceed 15m. During this period, it can be dynamically adjusted according to the monitoring and measurement data. The prerequisite for the excavation of pilot tunnel of section e in step four is that the right side of the lower step reaches the bottom and forms a safe step distance with it, that is, the working face of pilot tunnel of section d is 15m ahead of pilot tunnel of section e.

[0013] Preferably, in step five, the guide tunnel f is excavated and forms a stepped excavation with the guide tunnel e. The length of the stepped excavation does not exceed 15m, and can be dynamically adjusted according to the monitoring and measurement data during the process. In step six, the pilot tunnel of section g is excavated, forming a three-stage excavation with the pilot tunnels in the excavation areas of steps five and four. The excavation length of each stage shall not exceed 15m, and can be dynamically adjusted according to the monitoring and measurement data during the process.

[0014] Preferably, the single excavation advance of a single pilot tunnel in each step does not exceed 1.5m.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention addresses the issue of large-span, extra-large cross-section underground spatial structures in soft rock strata by dividing the entire cross-section into seven pilot tunnels for sectional excavation. Initial support is immediately implemented after the pilot tunnels are excavated, eliminating the phenomenon of increased arch crown settlement due to stress relaxation at the tunnel face caused by excessive span. This enhances the stability of the excavation face and effectively controls the settlement of the arch crown and the ground surface.

[0016] 2. By merging the excavation of the lower bench of the core rock column with the lower bench of the left side, this invention not only significantly reduces the excavation steps, but also optimizes the support structure, greatly reducing the amount of temporary support work, saving on the installation and dismantling of temporary support, and significantly saving the cycle time of support work, thus improving construction efficiency.

[0017] 3. When constructing the core rock pillar, this invention elongates the lower and middle steps, increases their width, and improves their slope, ensuring safe passage for personnel and equipment. It effectively solves the problem of difficult excavation of the upper steps in the core soil, reduces the mutual influence between processes, and significantly improves construction efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is an exploded view of the structure of the present invention; Figure 3 This is a detailed structural diagram of the first support mechanism of the present invention; Figure 4 This is a schematic diagram of the distributed excavation method of the present invention; Figure 5 This is a schematic diagram of the support structure after the initial excavation of this invention; Figure 6 This is a schematic diagram of the support structure after further excavation according to the present invention; Figure 7 This is a schematic diagram of the support structure after further excavation according to the present invention; Figure 8 This is a schematic diagram of the support structure after excavation is completed according to the present invention.

[0019] In the diagram: 1. Positioning mechanism; 101. Positioning seat; 102. First anchor hole; 103. Connecting shaft; 2. First support mechanism; 201. First support plate; 202. First support rod; 203. Second support rod; 204. Third support rod; 205. Second anchor hole; 3. Positioning frame; 4. Second support mechanism; 401. Second support plate; 402. Movable hole. Detailed Implementation

[0020] 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 some embodiments of the present invention, and not all embodiments. 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.

[0021] like Figures 1 to 3 As shown, the present invention provides an excavation auxiliary device suitable for underground space structures in soft rock strata, including a positioning mechanism 1, a first support mechanism 2 rotatably connected to the middle of the positioning mechanism 1, a positioning frame 3 installed on the top of the positioning mechanism 1, and a second support mechanism 4 rotatably connected to the middle of the positioning frame 3. The first support mechanism 2 includes a first support plate 201, a first support rod 202, a second support rod 203, and a third support rod 204. The first support plate 201 is rotatably connected to the positioning mechanism 1. The first support rod 202 is movably connected inside the first support plate 201. The second support rod 203 is movably connected inside the first support rod 202. The third support rod 204 is movably connected inside the second support rod 203.

[0022] The above scheme is adopted as follows: When excavating the two pilot tunnels a and b, two sets of devices are placed alternately on the two side walls of the pilot tunnels, and the positioning mechanism 1 is fixed by anchor bolts to achieve preliminary support for the two pilot tunnels a and b. After preliminary support, the movable ends of the two sets of first support mechanisms 2 inside the same pilot tunnel are staggered, and the two sets of second support mechanisms 4 are staggered together by rotation and point synchronously towards the side wall of the pilot tunnel. The two sets of second support mechanisms 4 can be locked by inserting bolts of appropriate size into the movable holes 402 to facilitate the support effect. In addition, the first support rod 202, the second support rod 203 and the third support rod 204 can move inside the first support plate 201, so as to extend when the first support plate 201 is vertical. By fixing the first support plate 201, the first support rod 202, the second support rod 203 and the third support rod 204, the support for the two pilot tunnels c and d is achieved, making the support more convenient.

[0023] like Figure 2 As shown, the positioning mechanism 1 includes a positioning seat 101, a first anchor hole 102 and a connecting shaft 103. The first anchor hole 102 is formed on the positioning seat 101, and the connecting shaft 103 is fixedly connected to the surface of the positioning seat 101. The positioning seat 101 is riveted to the tunnel through the first anchor hole 102.

[0024] The above scheme allows the device to be easily riveted to the tunnel through the first anchor hole 102, forming a fulcrum. At the same time, the connecting shaft 103 facilitates the rotation of the first support plate 201, thereby realizing the reversal of the support and improving the support effect.

[0025] like Figure 2 As shown, the first support mechanism 2 also includes a second anchor hole 205, which is disposed on the surface of the first support plate 201, the first support rod 202, the second support rod 203 and the third support rod 204.

[0026] The above scheme allows for convenient permanent support after all pilot tunnels have been excavated, thanks to the second anchor hole 205. Anchor bolts are passed through the second anchor hole 205 for fixation, achieving permanent support. Alternatively, during the excavation of pilot tunnels c and d, anchor bolts can be passed through the second anchor hole 205 on the first support rod 202, the second support rod 203, or the third support rod 204 to lock them in place, thus achieving the desired support effect.

[0027] like Figure 2 As shown, the second support mechanism 4 includes a second support plate 401 and a movable hole 402. The second support plate 401 is rotatably connected to the positioning frame 3, and the movable hole 402 is opened on the side of the second support plate 401.

[0028] The above solution is adopted: the second support plate 401 can support the arc-shaped sides of the two guide pits a and b, and the movable hole 402 can be used to lock the two sets of second support plates 401 with bolts of appropriate size when they are intersecting, and can also be used to lock and support them individually with the connectors in the prior art.

[0029] like Figure 2 As shown, both the first support plate 201 and the second support plate 401 are toothed, and the second support plate 401 and the first support plate 201 are interlocked.

[0030] The above scheme allows for the interleaving of the two sets of devices with the same structure, thus requiring only a few auxiliary devices for support.

[0031] like Figures 4 to 8 As shown, the present invention also provides an excavation method using an excavation auxiliary device suitable for underground space structures in soft rock strata, comprising the following steps: The large-span, extra-large cross-section is divided into nine regions, specifically three vertical layers (upper, middle, and lower) and three horizontal sections (left, middle, and right). Each region's width is 33%–38% of the total cross-section span, and its height is 30%–35% of the total cross-section height. The soil within the tunnel excavation section is further divided into seven sections: a, b, c, d, e, f, and g. Pilot tunnels are excavated in these sections, with the auxiliary excavation channel leading to the upper pilot tunnel of the main tunnel, completing the construction of the intersection system transition section. Specifically: section a is the upper bench of the left section; sections b, c, and d are the upper, middle, and lower benches of the right section; section e is the upper bench of the core rock pillar; section f includes the middle bench of the left section and the middle bench of the core rock pillar; and section g includes the lower bench of the left section and the lower bench of the core rock pillar. Step 1: First, excavate two pilot tunnels, section a and section b, and promptly implement temporary support. Section a is connected to the auxiliary excavation channel. Step 2: Excavate the pilot tunnel in section C and promptly implement initial support. Step 3: Excavate the pilot tunnel at section d and promptly implement initial support. Step 4: Excavate the pilot tunnel in section e and promptly implement temporary support; Step 5: Excavate the pilot tunnel of section f and promptly implement temporary support; Step Six: Excavate the pilot tunnel at section g and promptly implement temporary support; Step 7: Carry out the invert arch lining and arch wall lining of the mined tunnel in an orderly manner to complete the construction of the large-span and extra-large cross-section underground space structure.

[0032] In step one, two pilot tunnels, section a and section b, on one side of the upper bench are excavated first. The excavation faces of the two pilot tunnels are staggered by no less than 15m before and after, and the upper benches of the left and right sides of the tunnel are connected one after the other. In step two, the pilot tunnel in section c is excavated. The length of the step excavation should not exceed 20m, and it can be dynamically adjusted according to the monitoring and measurement data.

[0033] In step three, the pilot tunnel d is excavated, which forms a step excavation with the pilot tunnel c. The length of the step excavation does not exceed 20m, and can be dynamically adjusted according to the monitoring and measurement data during the process. In step four, the pilot tunnel of section e is excavated. The length of the step excavation shall not exceed 15m. During this period, it can be dynamically adjusted according to the monitoring and measurement data. The prerequisite for the excavation of pilot tunnel of section e in step four is that the right side of the lower step reaches the bottom and forms a safe step distance with it, that is, the working face of pilot tunnel of section d is 15m ahead of pilot tunnel of section e.

[0034] In step five, the pilot tunnel f is excavated and forms a step excavation with the pilot tunnel e. The length of the step excavation does not exceed 15m, and can be dynamically adjusted according to the monitoring and measurement data. In step six, the pilot tunnel of section g is excavated, forming a three-stage excavation with the pilot tunnels in the excavation areas of steps five and four. The excavation length of each stage shall not exceed 15m, and can be dynamically adjusted according to the monitoring and measurement data during the process.

[0035] In each step, the single excavation advance of a single pilot tunnel shall not exceed 1.5m.

[0036] Working principle and usage process of this invention: After excavating the two pilot tunnels a and b, two sets of auxiliary devices are placed in the two pilot tunnels respectively, and the positioning mechanism 1 is fixed to the side of the tunnel by anchor bolts. The first support plate 201 located in the same pilot tunnel is in an interleaved state. After excavating the pilot tunnels c and d, the first support plate 201 is made vertical, and the first support rod 202, the second support rod 203 and the third support rod 204 are pulled out from inside the first support plate 201. When the second anchor holes 205 on the surfaces of the three rods coincide and the third support rod 204 contacts the bottom of the pilot tunnel, the rods are locked in the second anchor holes 205 by bolts of appropriate size to form a support. After excavating the pilot tunnel in section e, rotate the second support plate 401, which is connected to the first support plate 201 in the vertical state, so that the second support plate 401 is riveted and fixed to the top of the pilot tunnel in section e to form a support. After excavating the pilot tunnels f and g, the first support plate 201, which was originally horizontal, is rotated to a vertical position. The first support rod 202, the second support rod 203, and the third support rod 204 are pulled out from inside the first support plate 201. Permanent support is achieved by anchoring rods through the second anchor holes 205 on the surfaces of the three rods. The bolts that were originally located in the middle area and were removed from the second anchor holes 205 on the surfaces of the first support rod 202, the second support rod 203, and the third support rod 204 are placed back into the first support plate 201. The first support plate 201 is then flipped upwards to fit against the top of the tunnel, and permanent support for the top is achieved by anchoring rods through the second anchor holes 205.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An excavation auxiliary device suitable for underground space structures in soft rock strata, characterized in that: It includes a positioning mechanism (1), a first support mechanism (2) is rotatably connected to the middle of the positioning mechanism (1), a positioning frame (3) is also installed on the top of the positioning mechanism (1), and a second support mechanism (4) is rotatably connected to the middle of the positioning frame (3). The first support mechanism (2) includes a first support plate (201), a first support rod (202), a second support rod (203) and a third support rod (204). The first support plate (201) is rotatably connected to the positioning mechanism (1). The first support rod (202) is movably connected inside the first support plate (201). The second support rod (203) is movably connected inside the first support rod (202). The third support rod (204) is movably connected inside the second support rod (203).

2. The excavation auxiliary device for underground space structures in soft rock strata according to claim 1, characterized in that: The positioning mechanism (1) includes a positioning seat (101), a first anchor hole (102) and a connecting shaft (103). The first anchor hole (102) is opened on the positioning seat (101), and the connecting shaft (103) is fixedly connected to the surface of the positioning seat (101). The positioning seat (101) is riveted to the tunnel through the first anchor hole (102).

3. The excavation auxiliary device for underground space structures in soft rock strata according to claim 1, characterized in that: The first support mechanism (2) further includes a second anchor hole (205), which is disposed on the surface of the first support plate (201), the first support rod (202), the second support rod (203) and the third support rod (204).

4. The excavation auxiliary device for underground space structures in soft rock strata according to claim 1, characterized in that: The second support mechanism (4) includes a second support plate (401) and a movable hole (402). The second support plate (401) is rotatably connected to the positioning frame (3), and the movable hole (402) is opened on the side of the second support plate (401).

5. The excavation auxiliary device for underground space structures in soft rock strata according to claim 4, characterized in that: The first support plate (201) and the second support plate (401) are both toothed, and the second support plate (401) and the first support plate (201) are interlocked.

6. An excavation method using an excavation auxiliary device suitable for underground space structures in soft rock strata, characterized in that: Includes the following steps, The large-span, extra-large cross-section is divided into nine regions, specifically three vertical layers (upper, middle, and lower) and three horizontal sections (left, middle, and right). Each region's width is 33%–38% of the total cross-section span, and its height is 30%–35% of the total cross-section height. The soil within the tunnel excavation section is further divided into seven sections: a, b, c, d, e, f, and g. Pilot tunnels are excavated in these sections, with the auxiliary excavation channel leading to the upper pilot tunnel of the main tunnel, completing the construction of the intersection system transition section. Specifically: section a is the upper bench of the left section; sections b, c, and d are the upper, middle, and lower benches of the right section; section e is the upper bench of the core rock pillar; section f includes the middle bench of the left section and the middle bench of the core rock pillar; and section g includes the lower bench of the left section and the lower bench of the core rock pillar. Step 1: First, excavate two pilot tunnels, section a and section b, and promptly implement temporary support. Section a is connected to the auxiliary excavation channel. Step 2: Excavate the pilot tunnel in section C and promptly implement initial support. Step 3: Excavate the pilot tunnel at section d and promptly implement initial support. Step 4: Excavate the pilot tunnel in section e and promptly implement temporary support; Step 5: Excavate the pilot tunnel of section f and promptly implement temporary support; Step Six: Excavate the pilot tunnel at section g and promptly implement temporary support; Step 7: Carry out the invert arch lining and arch wall lining of the mined tunnel in an orderly manner to complete the construction of the large-span and extra-large cross-section underground space structure.

7. The excavation method of the excavation auxiliary device for underground space structures in soft rock strata according to claim 6, characterized in that: In step one, two pilot tunnels, section a and section b, are excavated on one side of the upper bench. The excavation faces of the two pilot tunnels are staggered by no less than 15m. The upper benches of the left and right sides of the tunnel are then connected one after the other. In step two, the pilot tunnel in section c is excavated. The length of the step excavation should not exceed 20m, and it can be dynamically adjusted according to the monitoring and measurement data.

8. The excavation method of the excavation auxiliary device for underground space structures in soft rock strata according to claim 6, characterized in that: In step three, the pilot tunnel d is excavated, forming a stepped excavation with the pilot tunnel c. The length of the stepped excavation does not exceed 20m, and can be dynamically adjusted according to the monitoring and measurement data during the process. In step four, the pilot tunnel of section e is excavated. The length of the step excavation shall not exceed 15m. During this period, it can be dynamically adjusted according to the monitoring and measurement data. The prerequisite for the excavation of pilot tunnel of section e in step four is that the right side of the lower step reaches the bottom and forms a safe step distance with it, that is, the working face of pilot tunnel of section d is 15m ahead of pilot tunnel of section e.

9. The excavation method of the excavation auxiliary device for underground space structures in soft rock strata according to claim 6, characterized in that: In step five, the pilot tunnel f is excavated and forms a stepped excavation with the pilot tunnel e. The length of the stepped excavation does not exceed 15m, and can be dynamically adjusted according to the monitoring and measurement data during the process. In step six, the pilot tunnel of section g is excavated, forming a three-stage excavation with the pilot tunnels in the excavation areas of steps five and four. The excavation length of each stage shall not exceed 15m, and can be dynamically adjusted according to the monitoring and measurement data during the process.

10. The excavation method of the excavation auxiliary device for underground space structures in soft rock strata according to claim 6, characterized in that: In each step, the single excavation advance of the single pilot tunnel shall not exceed 1.5m.

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