A temporary invert removal and replacement structure and process for a tunnel under construction by the CRD method

Abstract

The present invention belongs to the technical field of underground space construction, and particularly relates to a structure and process for demolishing and replacing the temporary invert in a tunnel constructed by the CRD method. Steel waling joint plates and steel plate small brackets are reserved along the tunnel excavation direction on the left and right sidewalls of the upper bench of the tunnel, and the steel waling joint plates and steel plate small brackets are 150 - 200 cm away from the temporary invert joint plate; the steel waling is fixedly connected to the steel waling joint plate, and the steel pipes are vertically connected to the steel waling on the left and right sidewalls through bolts. The structure for demolishing and replacing the temporary invert in a tunnel constructed by the CRD method of the present invention is an assembled steel waling structure, and the assembled steel waling structure bears force during the blasting of the lower bench, reducing the deformation of the temporary invert on the upper bench caused by blasting and reducing the impact on the temporary invert caused by blasting.

Description

Technical Field

[0001] The invention belongs to the technical field of underground space construction, and particularly relates to a structure and process for demolishing and replacing a temporary inverted arch in a tunnel constructed by the CRD method. Background Technique

[0002] During the construction of urban shallow-buried large-section tunnels, in order to control ground settlement and in-tunnel convergence deformation, the CRD or CD construction method is mostly used for excavation. The construction and demolition of the temporary inverted arch and the vertical middle partition wall are the keys to controlling tunnel excavation and settlement deformation.

[0003] When the CRD construction method is used, if the stratum distribution is uneven and there is a soft upper and hard lower stratum, after the upper bench construction is completed, a temporary inverted arch is erected to form a temporary closed loop, and the upper bench of the tunnel is in a safe stress state. However, when the lower bench is to be excavated, since the lower bench stratum is hard, such as a rock stratum, blasting construction is required. The blasting vibration caused by the blasting construction will have a certain impact on the temporary inverted arch. Because the upper bench has been excavated and the soil above the temporary inverted arch has been excavated, it is a cavity. The lower part of the temporary inverted arch is closely attached to the unexcavated soil of the lower bench. After the lower bench is blasted, it will cause the deformation of the temporary inverted arch, resulting in the convergence and settlement of the completed upper bench in the tunnel. Summary of the Invention

[0004] The invention provides a structure and process for demolishing and replacing a temporary inverted arch in a tunnel constructed by the CRD method to solve the deficiencies of the prior art.

[0005] The invention is realized through the following technical solutions:

[0006] A structure for demolishing and replacing a temporary inverted arch in a tunnel constructed by the CRD method includes a steel waling. The steel waling is respectively fixed on the left side wall and the right side wall of the upper bench of the tunnel. Steel waling joint plates and steel plate calves are reserved on the left side wall and the right side wall of the upper bench of the tunnel along the tunnel excavation direction. The steel plate calves are embedded below the steel waling joint plates, and the steel waling joint plates are 150 - 200 cm above the temporary inverted arch joint plates; the steel waling is fixedly connected with the steel waling joint plates, and the steel walings on the left side wall and the right side wall are connected by steel pipes at intervals.

[0007] The spacing of the steel pipes is 2 - 3 m.

[0008] Both ends of the steel pipes are provided with steel pipe joint plates, and the steel pipe joint plates are fixedly connected with the steel waling by bolts.

[0009] The steel waling is fixedly connected with the steel waling joint plates by bolts.

[0010] The invention also includes a process for demolishing and replacing a temporary inverted arch in a tunnel constructed by the CRD method, which includes the following steps:

[0011] (1) In the construction of the upper bench of the tunnel, after excavation, the initial support steel arch is erected, the temporary inverted arch is constructed, and steel waling joint plates and steel plate small brackets are reserved on both the left and right side walls of the upper bench at a position 150 - 200 cm above the joint plate of the temporary inverted arch. The reserved steel waling joint plates and steel plate small brackets are arranged along the tunnel excavation direction, and the steel plate small brackets are embedded below the steel waling joint plates.

[0012] (2) When the upper bench advances 15 - 20 m, the steel walings are respectively fixedly connected to the steel waling joint plates on the left and right side walls of the upper bench by bolts, and then the steel walings on the left and right side walls are fixedly connected together through steel pipes; steel pipe joint plates are provided at both ends of the steel pipes, and the steel pipe joint plates are fixedly connected to the steel walings by bolts; the steel pipes are perpendicular to the steel walings, and one steel pipe is fixedly connected between the two side steel walings at intervals of 2 - 3 m along the tunnel excavation direction. The steel walings on the left and right side walls and the steel pipes form a prefabricated steel waling.

[0013] (3) After the construction of the prefabricated steel waling above the temporary inverted arch is completed, the lower bench is subjected to blasting construction, and the one - time excavation cycle footage is controlled; the construction of the lower bench for 2 - 3 m is the footage of each blasting construction cycle, and 15 - 20 m is a construction unit for the initial support of the lower bench.

[0014] (4) When the lower bench is constructed to a distance of 5 m from the heading face of the upper bench, the upper bench is excavated again; the muck from the excavation of the upper bench in this step is used to backfill the lower bench, and the backfill footage reaches the heading face of the lower bench, and the backfill height reaches 1 m below the temporary inverted arch, and a ramp is formed by backfilling the lower bench; at the same time, the temporary inverted arch is demolished, and the prefabricated steel waling near the upper bench is demolished. The demolition of the prefabricated steel waling near the upper bench is based on not affecting the transportation passage, and the remaining prefabricated steel walings are retained. Retaining the remaining prefabricated steel walings can support the two side walls in the tunnel and reduce the convergence deformation in the tunnel. When the upper bench advances 15 - 20 m, the inverted arch of the secondary lining follows up in time. After the inverted arch of the secondary lining follows up and the tunnel convergence settlement deformation monitoring is stable, the remaining prefabricated steel walings in step (1) are demolished. The demolished prefabricated steel walings are used for installation in the construction of the prefabricated steel waling of the upper bench in this step, and are recycled in this way.

[0015] (5) The excavation of the upper and lower benches of the tunnel is carried out in a cycle according to steps (1) to (4).

[0016] As an optimized solution:

[0017] In step (3), controlled blasting with micro - vibration is adopted to control the blasting vibration velocity.

[0018] In step (2), the length of the prefabricated steel waling is 15 - 20 m, which is the same as the construction unit of the lower bench.

[0019] The present invention is applicable to the construction of tunnels using the CRD method. When the geology of the upper and lower benches is uneven, with soft upper and hard lower, and blasting construction is adopted for the lower bench, the temporary inverted arch demolition and replacement structure in the tunnel during the CRD method construction of the present invention is an assembled steel waling structure. The assembled steel waling structure bears the force during the blasting of the lower bench, reducing the deformation of the temporary inverted arch of the upper bench caused by blasting and reducing the impact on the temporary inverted arch due to blasting.

[0020] How to control the excavation footage of the upper and lower benches and the left and right pilot tunnels during the excavation of the upper and lower benches is a key element in the construction technology. The construction technology of the present invention stipulates that the left and right pilot tunnels are respectively driven forward, and the excavation step distance of the two pilot tunnel faces is not less than 15 m; the step distance between the upper and lower benches of one pilot tunnel is not less than 5 m. After the upper bench is driven forward 15 m, the excavation of the upper bench is suspended and the excavation of the lower bench is turned to. At the same time, when the construction of the lower bench is converted to the construction of the upper bench, the initial support of the lower bench is backfilled with crushed stone for counterpressure, and a ramp is formed by using the crushed stone as the transportation channel for the excavation of the upper bench, facilitating the operation of construction vehicles and machinery to the upper bench, which is energy-saving, environmentally friendly and highly efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the present invention.

[0022] Figure 2 It is a schematic diagram of the assembled steel waling structure of the present invention.

[0023] In the figure, 1 is the upper bench, 2 is the lower bench, 3 is the temporary inverted arch, 4 is the steel pipe, and 5 is the steel waling. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following specific embodiments of the present invention are given. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solution of the present application fall within the protection scope of the present invention.

[0025] The replacement structure for removing the temporary invert in the tunnel during the construction of the CRD method of the present invention includes a steel purlin 5. The steel purlin 5 is made of double 25# I-beams. The steel purlin 5 is fixed on the left and right side walls of the upper bench 1 of the tunnel. Steel purlin joint plates and steel plate calves are reserved along the tunnel excavation direction on the left and right side walls of the upper bench 1 of the tunnel. The steel plate calves are located below the steel purlin joint plates and support the steel purlin joint plates. The steel purlin joint plates are located 150 - 200 cm above the temporary invert joint plates of the upper bench 1 of the tunnel. The steel purlin 5 and the steel purlin joint plates are fixedly connected together by bolts, so that the steel purlin 5 is respectively fixed on the left and right side walls of the upper bench 1 of the tunnel along the tunnel excavation direction. The steel purlins 5 on the left and right side walls are braced by steel pipes 4. The steel pipes 4 are seamless steel pipes with a diameter of 200 mm. Pipe joint plates are prefabricated at both ends of the steel pipes 4, and the pipe joint plates at both ends are respectively connected to the steel purlins 5 on both sides. The pipe joint plates and the steel purlins 5 are connected by bolts. Here, the bolt connection can be disassembled and assembled quickly and is convenient for reuse. One steel pipe 4 is arranged every 2 - 3 m between the steel purlins 5 on both sides. In this way, the steel purlins 5 on the left and right side walls of the upper bench 1 and the steel pipes 4 connecting the steel purlins 5 form an assembled steel purlin structure. The assembled steel purlin structure bears the load, reduces the deformation of the temporary invert 3 caused by blasting, and this structure can be demolished and reused cyclically.

[0026] Preferably, the length of the steel purlin 5 is 15 - 20 m, and the length of the steel purlin 5 is the same as that of the construction unit of the lower bench 2. The construction of the lower bench 2 is carried out in units of 15 - 20 m.

[0027] A process for replacing the removed temporary invert in the tunnel during the construction of the CRD method includes the following steps:

[0028] (1) Construction of the upper bench 1 of the tunnel. After excavation, the initial support steel arch is erected, the temporary invert 3 is constructed, and steel purlin joint plates and steel plate calves are reserved 150 - 200 cm above the temporary invert joint plates. The temporary invert joint plates are the joint plates connecting the arches at the position of the temporary invert 3. The reserved steel purlin joint plates and steel plate calves are fixed on the left and right side walls of the upper bench 1. The steel purlin joint plates and the steel plate calves are along the tunnel excavation direction. The steel plate calves are embedded below the steel purlin joint plates to support the steel purlin joint plates. The steel purlin joint plates are used for connecting the steel purlin 5 later, and the steel plate calves are used for further supporting the steel purlin joint plates and the steel purlin 5.

[0029] (2) When the upper bench 1 has advanced a certain distance, generally 15 - 20 m, install the steel purlin 5 above the temporary inverted arch 3 in step (1). The steel purlin 5 is installed along the tunnel excavation direction. First, fix and connect the steel purlin 5 to the steel purlin joint plates on the left and right side walls of the upper bench 1 respectively through bolts, so that the direction of the fixed steel purlin 5 is consistent with the tunnel excavation direction; then fix and connect the steel purlins 5 on the left and right side walls together through the steel pipes 4. The two ends of the steel pipe 4 are provided with steel pipe joint plates, and the steel pipe joint plates are fixed and connected to the steel purlin 5 through bolts. The steel pipe 4 is perpendicular to the steel purlins 5 on both sides, and one steel pipe 4 is fixedly connected between the steel purlins 5 on both sides every 1 m along the tunnel excavation direction. In this way, the steel purlins 5 on the left and right side walls and the steel pipes 4 form an assembled steel purlin.

[0030] (3) After the construction of the assembled steel purlin above the temporary inverted arch 3 is completed, the lower bench 2 can carry out blasting construction. The blasting adopts micro-vibration blasting to control the blasting vibration velocity and control the one-time excavation cycle footage. The construction footage of the lower bench is 2 - 3 m for each blasting construction cycle, and 15 - 20 m is an initial support construction unit for the lower bench.

[0031] (4) When the lower bench 2 is 5 m away from the face of the upper bench 1 during construction, the upper bench 1 is excavated again. First, use the stone slag after the excavation of the upper bench 1 in this step to backfill the lower bench 2. The backfill footage reaches the face of the lower bench 2, and the backfill height is 1 m below the temporary inverted arch 3. The lower bench 2 is backfilled to form a ramp to facilitate the passage of vehicles and machinery to the upper bench 1; at the same time, the temporary inverted arch 3 is demolished, and the assembled steel purlin near the upper bench 1 is demolished. The demolition of the assembled steel purlin near the upper bench 1 is based on not affecting the passage of vehicles and machinery. The remaining assembled steel purlins are retained as a safety reserve to further support the side walls on both sides in the tunnel and reduce the convergence deformation in the tunnel. Use the backfilled stone slag to carry out temporary counter-pressure support for the initial support of the lower bench 2 to avoid convergence deformation.

[0032] When the upper bench 1 has advanced a certain distance, generally 15 - 20 m, demolish the remaining assembled steel purlins in step (1). The demolished assembled steel purlins are used for installation in the construction of the upper bench 1 in this step and are recycled in this way.

[0033] (5) Cycle the excavation of the upper and lower benches of the tunnel according to steps (1) to (4).

[0034] The above-described embodiments are only one of the more preferred specific embodiments of the present invention. The ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction technology for demolishing and replacing the temporary invert in a tunnel during CRD method construction, characterized in that: It includes a structure for demolishing and replacing the temporary invert inside the tunnel constructed by the CRD method. The structure for demolishing and replacing the temporary invert inside the tunnel constructed by the CRD method includes steel wales (5). The steel wales (5) are respectively fixed on the left sidewall and the right sidewall of the upper bench (1) of the tunnel. On the left sidewall and the right sidewall of the upper bench (1) of the tunnel, steel wale joint plates and steel plate small brackets are reserved along the tunnel excavation direction. The steel plate small brackets are embedded under the steel wale joint plates. The steel wale joint plates are 150 - 200 cm above the temporary invert joint plates. The steel wales (5) are fixedly connected to the steel wale joint plates. The steel wales (5) on the left sidewall and the right sidewall are connected by steel pipes (4) at intervals. The process for demolishing and replacing the temporary invert inside the tunnel constructed by the CRD method includes the following steps: (1) Construction of the upper bench (1) of the tunnel. After excavation, the initial support steel arch is erected, the temporary invert (3) is constructed, and steel wale joint plates and steel plate small brackets are reserved on both the left sidewall and the right sidewall of the upper bench (1) at a position 150 - 200 cm above the temporary invert joint plates. The reserved steel wale joint plates and steel plate small brackets are along the tunnel excavation direction, and the steel plate small brackets are embedded under the steel wale joint plates. (2) When the upper bench (1) advances 15 - 20 m, the steel wales (5) are respectively fixedly connected to the steel wale joint plates on the left sidewall and the right sidewall of the upper bench (1) by bolts, and then the steel wales (5) on the left sidewall and the right sidewall are fixedly connected together by steel pipes (4). Steel pipe joint plates are provided at both ends of the steel pipe (4), and the steel pipe joint plates are fixedly connected to the steel wale (5) by bolts. The steel pipe (4) is perpendicular to the steel wale (5), and one steel pipe (4) is fixedly connected between the steel wales (5) on both sides at intervals of 1 m along the tunnel excavation direction. The steel wales (5) on the left sidewall and the right sidewall and the steel pipes (4) form an assembled steel wale. (3) After the construction of the assembled steel wale on the upper part of the temporary invert (3) is completed, blasting construction is carried out on the lower bench (2), and the one - time excavation cycle footage is controlled. The construction footage of the lower bench (2) for each blasting construction cycle is 2 - 3 m, and 15 - 20 m is an initial support construction unit for the lower bench (2). (4) When the distance between the constructed lower bench (2) and the face of the upper bench (1) is 5 m, the upper bench (1) is excavated again. The stone slag after the excavation of the upper bench (1) in this step is used to backfill the lower bench (2). The backfill footage reaches the face of the lower bench (2), and the backfill height reaches 1 m below the temporary invert (3). A ramp is formed by backfilling the lower bench (2). At the same time, the temporary invert (3) is demolished, and the assembled steel wale near the upper bench (1) is demolished. The demolition of the assembled steel wale near the upper bench (1) is based on not affecting the transportation passage, and the remaining assembled steel wales are retained. When the upper bench (1) advances 15 - 20 m, the remaining assembled steel wales in step (2) are demolished, and the demolished assembled steel wales are used for installation in the construction of the assembled steel wale of the upper bench (1) in this step, and are recycled in this way. (5) The excavation of the upper and lower benches (2) of the tunnel is carried out in cycles according to steps (1) to (4).

2. The construction tunnel temporary invert removal and replacement process by CRD method according to claim 1, characterized in that: In step (iii), controlled blasting with micro-vibration is adopted to control the blasting vibration velocity.

3. The temporary invert removal and replacement process in the tunnel during CRD method construction according to claim 1, characterized in that: In step (ii), the assembled steel waling has a length of 15 - 20 m, which is consistent with the construction unit of the lower bench (2).

4. The temporary invert removal and replacement process in the tunnel during CRD method construction according to claim 1, wherein: The spacing of the steel pipes (4) is 2 - 3 m.

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