Large-gradient subway underground excavation entrance and exit down-dip excavation construction method

Abstract

The invention discloses a large-gradient subway underground excavation entrance and exit downward excavation construction method, and belongs to the technical field of subway construction. During process conversion of the straight section and the slope section, the middle step of the slope section needs to synchronously follow the upper step to the same tunnel face, and a construction operation face is created for operation equipment; after conversion construction is completed, an upper step of the slope section continues to be excavated, follow-up construction is conducted on the upper step in the mode that a rock shoulder is reserved and a trapezoidal middle groove is excavated in the middle at the position of the middle step, excavated muck is backfilled into a groove in the excavated position, and a muck transportation ramp not larger than 10 degrees is formed; and after excavation of the upper step of the through section is completed, the through section needs to be communicated with the direction of the station body, then the step falls in the reverse direction of the transverse channel communicated with the direction of the station, then excavation construction of the remaining slope section is conducted, and finally muck backfilled by the slope is cleaned to the hard rock base plane. According to the construction method, the construction speed is high, the down-dip excavation construction risk can be reduced, and the problems that the safety risk is large and the construction period is difficult in down-dip excavation construction of the large-gradient subway underground excavation entrance and exit can be effectively solved.

Description

Technical Field

[0001] The invention relates to a method for digging a steeply sloped subway entrance and exit, and belongs to the technical field of subway construction. Background Art

[0002] The auxiliary entrance and exit structures in subway stations are constructed using the shallow buried tunnel method. Due to various factors such as their small width, high clearance, shallow buried depth, and short length, the slope section has a large angle (up to 30°). In order to reduce safety risks, some cities strictly prohibit the use of the overhead excavation construction method.

[0003] When using the downward excavation construction method, due to the special positional relationship between the slope section and the straight section, it is difficult for the excavation equipment to carry out earthwork operations on the slope section step method on the straight section. After the subsequent excavation of the upper steps, earthwork operations can only be carried out by using a micro excavator + 2 excavators relaying excavation, which has low construction efficiency and high construction safety risks. Summary of the invention

[0004] In view of the above-mentioned defects existing in the prior art, the present invention provides a method for digging for a subway entrance and exit with a large slope, which has high construction efficiency and construction safety.

[0005] The present invention is realized by the following technical scheme: a method for digging a steeply sloped subway entrance and exit, wherein the subway entrance and exit comprises a slope section and a through section arranged in sequence from top to bottom, wherein the upper part of the slope section is connected to a straight section constructed by open excavation, and the through section is connected to the station by a connecting section, and the slope section and the through section are constructed by a three-step method, and the method is characterized in that the method comprises the following steps:

[0006] (1) Construction conversion between the straight section and the slope section: After the excavation of the straight section is completed, the excavator continues to excavate the upper steps of the slope section on the straight section; when the upper steps of the slope section are excavated to the point where the space is limited and it is impossible to continue excavating, the middle steps need to be followed up to the same tunnel face to create a construction working surface for the operating equipment;

[0007] (2) Excavation of the upper steps of the slope section: After the conversion construction of the straight section and the slope section is completed, the upper steps of the slope section will continue to be excavated; in order to ensure the working space of the excavator and take into account the requirement of 5-10m staggered distance of the designed steps, a rock shoulder is reserved at the middle step position, and a trapezoidal middle groove is excavated in the middle to follow up the construction with the upper steps. The upper arch frame is supported by the reserved rock shoulder. The upper width of the trapezoidal middle groove is 4-5m, and the lower width is 3-4m. The excavated slag is backfilled into the groove at the excavated position to form a slag transportation ramp with an angle of no more than 10°;

[0008] (3) Excavation of the middle and lower steps of the slope section: After the step offset reaches the design requirement, the excavation and support construction of the middle and lower steps shall be followed up in a timely manner. The excavation of the middle step is consistent with that of the upper step. Rock shoulders are reserved on both sides to meet the step offset requirements. Grooves are drawn in the middle to ensure the operating space of the excavation machinery. The slag is backfilled to the excavated position of the middle and lower steps of the slope section to form a slag transportation ramp with an angle of no more than 10°.

[0009] (4) Reverse excavation of the through-section: After the excavation of the upper steps of the through-section is completed, it is necessary to connect with the main direction of the station, and then go down the steps in the opposite direction of the horizontal passage connected to the station direction to carry out the excavation of the remaining slope section. Finally, the backfill soil of the ramp is cleaned to the hard rock base.

[0010] Furthermore, the width of the reserved rock shoulder is not less than 1.5 meters.

[0011] Furthermore, in step (3), when breaking the rock shoulders on both sides, it should be broken on one side or on both sides alternately to ensure the stability of the primary support structure.

[0012] The beneficial effects of the present invention are as follows: when the process of the straight section and the slope section is switched, the middle step of the slope section synchronously follows the upper step to the same face, which can create a construction space for excavators and other operating equipment to ensure the construction of the operating equipment during the process conversion; when the upper step of the slope section is excavated, the middle groove is excavated and the rock shoulder is reserved in the middle step position, which can ensure the equipment working space and support the upper arch frame through the rock shoulder, which can effectively reduce the construction safety risk; by reverse excavation at the through position, the construction difficulty can be effectively reduced and the construction efficiency can be improved. Through reasonable process adjustment, the present invention optimizes the large-angle dark excavation channel designed as 30° to a small-angle construction channel suitable for slag vehicles to travel no more than 10°, with a small slope and fast slag speed, and can optimize the relay excavation of multiple excavators to a single excavator cooperating with the engineering slag transport vehicle to excavate, achieving the purpose of fast and efficient construction; the present invention simplifies the construction steps, has high construction efficiency, low construction risk, and controllable construction safety. The construction method of the present invention is highly practical, highly operable and has a fast construction speed, and effectively solves the problems of high safety risks and difficulty in meeting construction deadlines in the downward excavation construction of underground subway entrances and exits with large slopes. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the subway entrance and exit in the present invention;

[0014] Figure 2 It is a longitudinal section schematic diagram of the subway entrance and exit in the present invention;

[0015] Figure 3 It is a schematic diagram of the present invention when the upper step excavation of the slope section is completed for 3m;

[0016] Figure 4It is a schematic diagram of the step in the slope section following up to the same tunnel face of the upper step in the present invention;

[0017] Figure 5 It is a schematic diagram of the longitudinal section of the step excavation on the slope section in the present invention;

[0018] Figure 6 This is a schematic diagram of the longitudinal section from the step excavation on the slope section to the end wall in the present invention.

[0019] Figure 7 It is a schematic cross-sectional view of the step excavation at the slope end in the present invention;

[0020] Figure 8 It is a schematic diagram of the excavation of the middle and lower steps in the present invention;

[0021] Fig. 9 It is a cross-sectional schematic diagram of the middle step excavation in the present invention;

[0022] Fig.10 It is a schematic diagram of the remaining middle and lower steps after reverse excavation of the through-part in the present invention;

[0023] Fig.11 It is a schematic diagram of cleaning the ramp slag filling in the present invention;

[0024] In the figure, 1, straight section, 2, slope section, 3, through section, 4, station connecting section. DETAILED DESCRIPTION

[0025] The present invention will be further described below by way of non-limiting embodiments and in conjunction with the accompanying drawings:

[0026] A method for digging a subway entrance with a steep slope, such as Figure 1-Figure 2 As shown, the underground excavation entrance and exit of the subway includes a slope section 2 and a through section 3 arranged in sequence from top to bottom. The upper part of the slope section 2 is connected to the straight section 1, and the through section 3 is connected to the station through the station connecting section 4. The straight section 1 is constructed by open excavation. When the underground excavation entrance and exit of the subway is constructed, the station connecting section 4 has been completed. The three-step method is used for the construction of the slope section 2 and the through section 3. It is characterized by comprising the following steps:

[0027] (1) Construction conversion between straight section 1 and slope section 2: After the excavation of straight section 1 is completed, the excavator continues to excavate the upper step of slope section 2 in straight section 1; after excavating 3m on the upper step of slope section 2, the space on the upper step is limited and excavation cannot continue. The middle step needs to be followed up to the same face to create a construction working surface for the excavator and other operating equipment. Figure 3 The figure shows the schematic diagram of the upper step of the slope section when the excavation is completed for 3m. Figure 4 Shown is a schematic diagram of the step in the slope section following up to the same face of the upper step.

[0028] (2) Excavation of the upper steps of the slope section: After the conversion construction of the straight section 1 and the slope section 2 is completed, continue to excavate the upper steps of the slope section 2. In order to ensure the working space of the excavator and take into account the requirement of designing a step stagger of 5-10m, a rock shoulder is reserved at the middle step position, and a trapezoidal middle trough is excavated in the middle to follow up the construction of the upper steps. The upper arch frame is supported by the reserved rock shoulder to reduce the safety risk. The upper width of the trapezoidal middle trough is 4-5m, and the lower width is 3-4m. The reserved rock shoulders on both sides are reasonably adjusted dynamically with the width of the trough, but shall not be less than 1.5 meters to ensure the safety and stability of the primary support structure. The excavated debris is backfilled into the groove at the excavated position to form a debris transportation ramp of no more than 10° to ensure the climbing ability of the debris transportation vehicles. As shown in the attached Figure 5 The figure shows the longitudinal section of the step excavation on the slope section. Figure 6 This is a schematic diagram of the longitudinal section from the step excavation on the slope section to the end wall. Figure 7 It is a schematic diagram of the cross section of the step excavation at the end of the slope.

[0029] (3) Excavation of the middle and lower steps of the slope section: After the step offset reaches the design requirement, the excavation and support construction of the middle and lower steps shall be followed up in time. The excavation of the middle step is consistent with the upper step. Rock shoulders are reserved on both sides to meet the step offset requirements. Grooves are made in the middle to ensure the operating space of the excavation machinery. The slag is backfilled to the excavated position of the middle and lower steps of the slope section to form a slag transportation ramp with an angle of no more than 10°, which is convenient for slag unloading vehicles to travel on the ramp. When breaking the rock shoulders on both sides, it is strictly forbidden to break them at the same time to prevent the grilles on both sides from being suspended in the air at the same time. It should be broken on one side or on both sides alternately to ensure the stability of the primary support structure. As shown in the attached figure, Figure 8 This is a schematic diagram of the excavation of the middle and lower steps. Fig. 9 This is the cross-sectional view of the middle step excavation.

[0030] (4) Reverse excavation of the through-section: After the upper steps are excavated to the end wall of the through-section, it is necessary to connect with the main direction of the station, and then go down the steps in the opposite direction of the cross passage connected to the station direction to excavate the remaining slope section. Finally, the backfilled soil of the ramp is cleaned to the hard rock base. Fig.10 This is a schematic diagram of the remaining middle and lower steps after reverse excavation of the through-section. Fig.11 It is a schematic diagram of clearing the slag from the ramp.

[0031] In the present invention, when the straight section and the slope section process are switched, the middle step of the slope section needs to synchronously follow the upper step to the same heading face, thereby creating an excavation and walking construction working surface for excavators and other operating equipment, ensuring the conversion of the straight section and the slope section process in the downward excavation construction; when excavating the upper step of the slope section, by excavating the middle groove and reserving the rock shoulder at the middle step position, the upper arch frame can be supported by the rock shoulder to effectively reduce the safety risk; by reverse excavation at the through position, the construction difficulty can be reduced and the construction efficiency can be improved.

[0032] The other parts of this embodiment are all prior art and will not be described in detail here.

Claims

1. A method for digging a steep subway entrance and exit, wherein the subway entrance and exit comprises a slope section and a through section arranged in sequence from top to bottom, the upper part of the slope section is connected to a straight section constructed by open excavation, the through section is connected to the station through a connecting section, and the slope section and the through section are constructed by a three-step method, wherein the characteristics are: The steps include: (1) Construction conversion between the straight section and the slope section: After the excavation of the straight section is completed, the excavator continues to excavate the upper steps of the slope section on the straight section; when the upper steps of the slope section are excavated to the point where the space is limited and it is impossible to continue excavating, the middle steps need to be followed up to the same tunnel face to create a construction working surface for the operating equipment; (2) Excavation of the upper steps of the slope section: After the conversion construction of the straight section and the slope section is completed, the upper steps of the slope section will continue to be excavated; in order to ensure the working space of the excavator and take into account the requirement of 5-10m staggered distance of the design steps, a rock shoulder is reserved at the middle step position, and a trapezoidal middle groove is excavated in the middle to follow up the construction with the upper steps. The upper arch frame is supported by the reserved rock shoulder. The upper width of the trapezoidal middle groove is 4-5m, and the lower width is 3-4m. The excavated slag is backfilled into the groove at the excavated position to form a slag transportation ramp with an angle of no more than 10°; (3) Excavation of the middle and lower steps of the slope section: After the step offset reaches the design requirement, the excavation and support construction of the middle and lower steps shall be followed up in a timely manner. The excavation of the middle step is consistent with that of the upper step. Rock shoulders are reserved on both sides to meet the step offset requirements. Grooves are drawn in the middle to ensure the operating space of the excavation machinery. The slag is backfilled to the excavated position of the middle and lower steps of the slope section to form a slag transportation ramp with an angle of no more than 10°. (4) Reverse excavation of the through-section: After the excavation of the upper steps of the through-section is completed, it is necessary to connect with the main direction of the station, and then go down the steps in the opposite direction of the horizontal passage connected to the station direction to carry out the excavation of the remaining slope section. Finally, the backfill soil of the ramp is cleaned to the hard rock base.

2. The method for digging a steep slope subway entrance and exit according to claim 1 is characterized by: The width of the reserved rock shoulder shall not be less than 1.5 meters.

3. The method for digging a steep slope subway entrance and exit according to claim 1 is characterized by: In step (3), when breaking the rock shoulders on both sides, it should be broken on one side or on both sides alternately to ensure the stability of the primary support structure.

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