阅读说明：本技术 一种并行小净距隧道的施工方法 (Construction method for parallel small-clear-distance tunnel ) 是由 杨伦 刘军波 郑杰 李骏 沈茂林 谢晶 叶绍其 田婷 付浩 黄中华 颉建中 颜 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种并行小净距隧道的施工方法,包括以下步骤：步骤1,先行隧道对中夹岩进行超前加固处理；步骤2,分三台阶开挖先行隧道的临近中夹岩一侧；步骤3,分三台阶开挖先行隧道的远离中夹岩一侧步骤4,后行隧道对中夹岩小导管加固并注浆处理；步骤5,分三台阶开挖后行隧道的临近中夹岩一侧；步骤6,分三台阶开挖后行隧道的远离中夹岩一侧；步骤7,浇筑先行隧道仰拱和拱墙；步骤8,浇筑后行隧道仰拱和拱墙。本发明通过对小净距隧道的中夹岩注浆加固处理,改善了围岩的力学性能,提高了中夹岩的稳定性,降低了后行隧道开挖对先行隧道的影响,同时采取分台阶控制爆破开挖及时施作初期支护来确保中夹岩和两隧道的稳定,提高了施工效率。(The invention discloses a construction method of a parallel small-clear-distance tunnel, which comprises the following steps: step 1, carrying out advanced reinforcement treatment on the middle sandwiched rock by a tunnel in advance; step 2, excavating one side, close to the middle clamped rock, of the advanced tunnel in three steps; step 3, excavating one side of the advanced tunnel far away from the middle clamped rock in three steps 4, and reinforcing and grouting the middle clamped rock small guide pipe in the backward tunnel; step 5, excavating the side, close to the middle clamped rock, of the backward tunnel in three steps; step 6, excavating one side of the backward tunnel far away from the middle clamped rock in three steps; step 7, casting an inverted arch and an arch wall of the prior tunnel; and 8, pouring an inverted arch and an arch wall of the backward tunnel. The method improves the mechanical property of surrounding rock, improves the stability of the middle clamped rock, reduces the influence of the excavation of a backward tunnel on a forward tunnel, ensures the stability of the middle clamped rock and two tunnels by controlling blasting excavation in different steps and applying primary support in time, and improves the construction efficiency.)

1. A construction method of parallel small-clear-distance tunnels is characterized by comprising the following steps: the method comprises the following steps:

step 1: carrying out advanced reinforcement treatment on the middle sandwiched rock by the advanced tunnel: horizontally and obliquely driving a plurality of small guide pipes into the constructed part serving as a working surface, connecting the small guide pipes with a grouting pump, pumping slurry into the middle rock clamp through the small guide pipes, and performing grouting reinforcement treatment on the middle rock clamp;

step 2: according to the designed step boundary, after the middle clamp rock grouting reinforcement reaches the design strength, excavating one side close to the middle clamp rock of the advanced tunnel by three steps and applying the initial support: 1) using a precedent tunnel steel frame erected by the previous cycle as a platform to construct a forepoling; 2) respectively excavating an upper step, a middle step and a lower step on one side close to the middle clamp rock; 3) constructing a prior tunnel steel frame and a temporary middle partition wall of the prior tunnel step by step; 4) drilling an arch radial system anchor rod, performing grid-connected concrete spraying to a designed thickness, simultaneously spraying concrete on the tunnel faces of the upper step and the middle step which are excavated to seal, and arranging a locking steel tube of a prior tunnel steel frame at the bottom of the lower step;

and step 3: excavating one side of the advanced tunnel far away from the middle rock according to the construction sequence of the step 2 in three steps and applying the side as an initial support of the advanced tunnel;

and 4, step 4: and (3) carrying out advanced reinforcement treatment on the middle sandwiched rock by the backward tunnel: horizontally and obliquely driving a plurality of small guide pipes into the constructed part serving as a working surface, connecting the small guide pipes with a grouting pump, pumping slurry into the middle rock clamp through the small guide pipes, and performing grouting reinforcement treatment on the middle rock clamp;

and 5: excavating one side of the backward tunnel close to the middle clamped rock in three steps according to the construction sequence of the step 2 and constructing a primary support of the backward tunnel;

step 6: excavating one side of the back tunnel, which is far away from the middle clamp rock, in three steps according to the construction sequence of the step 2 and constructing a primary support of the back tunnel;

and 7: pouring an inverted arch of the advanced tunnel, and pouring the arch wall of the advanced tunnel at one time by using a two-lining template trolley after the inverted arch concrete reaches the design strength;

and 8: and (4) pouring an inverted arch of the backward tunnel, and pouring the inverted arch concrete into the backward tunnel arch wall at one time by using a two-lining template trolley after the inverted arch concrete reaches the design strength, so as to complete the construction of the small clear distance section of the two tunnels.

2. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in the step 1, small guide pipes with the length of 5m and the fixed diameter of 50 are horizontally and obliquely arranged to carry out grouting reinforcement on the middle rock interlayer between the preceding tunnel and the following tunnel.

3. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in step 2, the distance between the upper step face of the side of the preceding tunnel adjacent to the middle clamping rock and the upper step face of the side of the following tunnel adjacent to the middle clamping rock is larger than 15 m.

4. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in the step 2, an upper step, a middle step and a lower step on one side close to the middle clamp rock are excavated, so that the middle clamp rock is supplemented with grouting and reinforced conveniently, and the stability of the middle clamp rock is further improved.

5. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in step 2, when the step excavation mode is selected to weak blasting excavation, the depth of blast holes and the loading amount should be strictly controlled.

6. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in the step 2, the primary support comprises a tunnel steel frame and net-sprayed concrete, the primary support is gradually constructed in the step excavation process, 4cm thick concrete is sprayed for sealing the surrounding rock in time after excavation, 8cm thick concrete sealing is sprayed on the face surfaces of the upper step and the middle step in time, and 10cm thick concrete is sprayed on the bottom of the step.

7. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in step 2, the length of each step is 3-5 m; and (3) selecting 6-8m for the distance between the lower step excavated in the step (2) and the upper step excavated in the step (3).

8. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: and (4) selecting the distance between the lower step excavated in the step (3) and the inverted arch of the previous tunnel poured in the step (7), and the distance between the inverted arch excavated in the step (3) and the arch wall of the previous tunnel poured in the step (7) to be 6-8 m.

9. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in step 2, the removal of the temporary middle partition wall of the tunnel can be performed after the primary support construction of the main structure of the tunnel body is finished and stabilized.

10. The construction method of the parallel small clear distance tunnel according to claim 1, characterized in that: in the step 7 and the step 8, the monitoring measurement is enhanced and the structural stability of the tunnel body is analyzed in the construction process, so that a basis is provided for adjusting the support parameters of the advance tunnel support and the backward tunnel support and pouring the arch wall of the advance tunnel.

Technical Field

The invention relates to the field of tunnel construction, in particular to a construction method of a parallel small-clear-distance tunnel.

Background

With the development of tunnel construction, parallel small-clear-distance tunnel construction is inevitable in the existing railway tunnel construction process. Whether the middle rock interlayer between the small clear distance tunnels is stable or not can bring certain potential safety hazards to the construction of the two tunnels, and the excavation of the backward tunnel can stably cause certain influence on the tunnel body of the forward tunnel, so that the construction of the small clear distance tunnel faces various difficulties. The thickness of the middle clamp rock is too small, stress release of tunnel construction can disturb the middle clamp rock to a certain extent, potential crack surfaces exist, instability damage can be caused if the stress release is improper, and particularly in the blasting construction process of a backward tunnel, the safety of a forward tunnel is seriously threatened. Therefore, it is necessary to adopt reinforcement technical measures and reasonable tunnel excavation procedures for the middle rock interlayer between two small-clearance tunnels to ensure the safety of the two tunnels during construction and operation and improve the construction progress.

Disclosure of Invention

The invention aims to provide a construction method of a parallel small clear distance tunnel, which is used for solving the problems of stability of a middle clamped rock and stability of a tunnel body structure of the parallel small clear distance tunnel, ensuring the safety of a construction process and improving the construction progress.

The purpose of the invention is realized as follows:

a construction method of parallel small clear distance tunnels is characterized in that: the method comprises the following steps:

step 1: carrying out advanced reinforcement treatment on the middle sandwiched rock by the advanced tunnel: horizontally and obliquely driving a plurality of small guide pipes into the constructed part serving as a working surface, connecting the small guide pipes with a grouting pump, pumping slurry into the middle rock clamp through the small guide pipes, and performing grouting reinforcement treatment on the middle rock clamp;

step 2: according to the designed step boundary, after the middle clamp rock grouting reinforcement reaches the design strength, excavating one side close to the middle clamp rock of the advanced tunnel by three steps and applying the initial support: 1) using a precedent tunnel steel frame erected by the previous cycle as a platform to construct a forepoling; 2) respectively excavating an upper step, a middle step and a lower step on one side close to the middle clamp rock; 3) constructing a prior tunnel steel frame and a temporary middle partition wall of the prior tunnel step by step; 4) drilling an arch radial system anchor rod, performing grid-connected concrete spraying to a designed thickness, simultaneously spraying concrete on the tunnel faces of the upper step and the middle step which are excavated to seal, and arranging a locking steel tube of a prior tunnel steel frame at the bottom of the lower step;

and step 3: excavating one side of the advanced tunnel far away from the middle rock according to the construction sequence of the step 2 in three steps and applying the side as an initial support of the advanced tunnel;

and 4, step 4: and (3) carrying out advanced reinforcement treatment on the middle sandwiched rock by the backward tunnel: horizontally and obliquely driving a plurality of small guide pipes into the constructed part serving as a working surface, connecting the small guide pipes with a grouting pump, pumping slurry into the middle rock clamp through the small guide pipes, and performing grouting reinforcement treatment on the middle rock clamp;

and 5: excavating one side of the backward tunnel close to the middle clamped rock in three steps according to the construction sequence of the step 2 and constructing a primary support of the backward tunnel;

step 6: excavating one side of the back tunnel, which is far away from the middle clamp rock, in three steps according to the construction sequence of the step 2 and constructing a primary support of the back tunnel;

and 7: pouring an inverted arch of the advanced tunnel, and pouring the arch wall of the advanced tunnel at one time by using a two-lining template trolley after the inverted arch concrete reaches the design strength;

and 8: and (4) pouring an inverted arch of the backward tunnel, and pouring the inverted arch concrete into the backward tunnel arch wall at one time by using a two-lining template trolley after the inverted arch concrete reaches the design strength, so as to complete the construction of the small clear distance section of the two tunnels.

In the step 1, small guide pipes with the length of 5m and the fixed diameter of 50 are horizontally and obliquely arranged to carry out grouting reinforcement on the middle rock interlayer between the preceding tunnel and the following tunnel.

In step 2, the distance between the upper step face of the side of the preceding tunnel adjacent to the middle clamping rock and the upper step face of the side of the following tunnel adjacent to the middle clamping rock is larger than 15 m.

In the step 2, an upper step, a middle step and a lower step on one side close to the middle clamp rock are excavated, so that the middle clamp rock is supplemented with grouting and reinforced conveniently, and the stability of the middle clamp rock is further improved.

In step 2, when the step excavation mode is selected to weak blasting excavation, the depth of blast holes and the loading amount should be strictly controlled.

In the step 2, the primary support comprises a tunnel steel frame and net-sprayed concrete, the primary support is gradually constructed in the step excavation process, 4cm thick concrete is sprayed for sealing the surrounding rock in time after excavation, 8cm thick concrete sealing is sprayed on the face surfaces of the upper step and the middle step in time, and 10cm thick concrete is sprayed on the bottom of the step.

In step 2, the length of each step is 3-5 m; and (3) selecting 6-8m for the distance between the lower step excavated in the step (2) and the upper step excavated in the step (3).

And (4) selecting the distance between the lower step excavated in the step (3) and the inverted arch of the previous tunnel poured in the step (7), and the distance between the inverted arch excavated in the step (3) and the arch wall of the previous tunnel poured in the step (7) to be 6-8 m.

In step 2, the removal of the temporary middle partition wall of the tunnel can be performed after the primary support construction of the main structure of the tunnel body is finished and stabilized.

In the step 7 and the step 8, the monitoring measurement is enhanced and the structural stability of the tunnel body is analyzed in the construction process, so that a basis is provided for adjusting the support parameters of the advance tunnel support and the backward tunnel support and pouring the arch wall of the advance tunnel.

Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:

1. the small guide pipe is used for grouting and reinforcing the middle clamp rock, so that the mechanical property of the middle clamp rock is changed, the stability and the deformation resistance of the middle clamp rock are improved, the reinforcing effect is reliable, the process is simple, and the cost is low;

2. the small conduit grouting reinforcement is carried out on the middle clamp rocks before the preceding tunnel excavation and the following tunnel excavation, so that the grouting distribution in the middle clamp rocks is more uniform, and the reinforcement effect of the middle clamp rocks can be improved;

3. the excavation design is reasonable, a multi-step weak blasting excavation mode is adopted, all parts are excavated and timely constructed for primary support, the stability and deformation control of surrounding rocks are facilitated, and meanwhile the construction efficiency is improved.

Drawings

FIG. 1 is a schematic plan view of the present invention;

FIG. 2 is a cross-sectional view of a construction step of the present invention;

FIG. 3 is a cross-sectional view of the construction of a longitudinal step of the present invention;

FIG. 4 is a schematic cross-sectional view of the small clearance tunnel vault settlement, clearance convergence and ground surface monitoring of the present invention;

in the figure: 1-an advanced tunnel, 2-a backward tunnel, 3-a middle clamp rock, 4-an upper step at the side of the advanced tunnel adjacent to the middle clamp rock, 5-a middle step at the side of the advanced tunnel adjacent to the middle clamp rock, 6-a lower step at the side of the advanced tunnel adjacent to the middle clamp rock, 7-an upper step at the side of the advanced tunnel far away from the middle clamp rock, 8-a middle step at the side of the advanced tunnel far away from the middle clamp rock, 9-a lower step at the side of the advanced tunnel far away from the middle clamp rock, 10-a temporary middle partition wall, 11-a primary support of the advanced tunnel, 12-an inverted arch of the advanced tunnel, 13-an arch wall of the advanced tunnel, 14-a small conduit, 15-an upper step at the side of the backward tunnel adjacent to the middle clamp rock, 16-a middle step at the side of the backward tunnel adjacent to the middle clamp rock, 17-a lower step at the side of the backward, 18-an upper step at one side of the backward tunnel far away from the middle clamp rock, 19-a middle step at one side of the backward tunnel far away from the middle clamp rock, 20-a lower step at one side of the backward tunnel far away from the middle clamp rock, 21-a radial system anchor rod, 22-a front support and 23-a front tunnel steel frame.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the invention relates to a construction method of a parallel small-clear-distance tunnel, which comprises the following steps:

step 1: carrying out advanced reinforcement treatment on the intermediate rocks 3 in the preceding tunnel 1: a plurality of small guide pipes 14 are horizontally and obliquely driven into the constructed part serving as a working surface, the small guide pipes 14 are connected with a grouting pump, slurry is pumped into the middle rock clamp 3 through the small guide pipes 14, and grouting reinforcement treatment is carried out on the middle rock clamp 3;

step 2: according to the designed step boundary, after the grouting reinforcement of the middle clamp rock 3 reaches the design strength, excavating one side of the prior tunnel 1 adjacent to the middle clamp rock 3 in three steps and applying as a prior tunnel primary support 11: 1) constructing a forepoling 22 by using a forepoling tunnel steel frame 23 erected in the previous cycle as a platform; 2) respectively excavating an upper step 4, a middle step 5 and a lower step 6 on one side close to the middle clamp rock; 3) gradually constructing a prior tunnel steel frame 23 and a prior tunnel temporary middle partition wall 10; 4) drilling an arch radial system anchor rod 21, connecting the grid and spraying concrete to a designed thickness, spraying concrete on the tunnel faces of the upper step 4 and the middle step 5 which are excavated to seal, and arranging a locking steel tube of a prior tunnel steel frame 23 at the bottom of the lower step 6;

and step 3: excavating one side of the advanced tunnel 1 far away from the middle clamp rock 3 in three steps according to the construction sequence of the step 2 and applying the side as an initial support 11 of the advanced tunnel;

and 4, step 4: and the backward tunnel 2 carries out advanced reinforcement treatment on the middle sandwiched rock 3: a plurality of small guide pipes 14 are horizontally and obliquely driven into the constructed part serving as a working surface, the small guide pipes 14 are connected with a grouting pump, slurry is pumped into the middle rock clamp 3 through the small guide pipes 14, and grouting reinforcement treatment is carried out on the middle rock clamp 3;

and 5: excavating one side of the backward tunnel 2 close to the middle clamp rock 3 in three steps according to the construction sequence of the step 2 and constructing a primary support of the backward tunnel;

step 6: excavating one side of the backward tunnel 2 far away from the middle clamp rock 3 in three steps according to the construction sequence of the step 2 and constructing a primary support of the backward tunnel;

and 7: casting a first tunnel inverted arch 12, and casting a first tunnel arch wall 13 by using a two-lining template trolley at one time after the inverted arch concrete reaches the design strength;

and 8: and (4) pouring an inverted arch of the backward tunnel, and pouring the inverted arch concrete into the backward tunnel arch wall at one time by using a two-lining template trolley after the inverted arch concrete reaches the design strength, so as to complete the construction of the small clear distance section of the two tunnels.

In the step 1, small guide pipes with the length of 5m and the diameter of 50 mm are horizontally and obliquely arranged to carry out grouting reinforcement on the middle rock interlayer between the preceding tunnel and the following tunnel.

In step 2, the distance between the upper step 4 face of the side of the preceding tunnel 1 adjacent to the middle clamp rock 3 and the upper step 15 face of the side of the following tunnel 2 adjacent to the middle clamp rock 3 is more than 15 m.

In the step 2, an upper step 4, a middle step 5 and a lower step 6 on one side close to the middle clamp rock are excavated, so that the middle clamp rock 3 is supplemented with grouting reinforcement, and the stability of the middle clamp rock 3 is further improved.

In step 2, when the step excavation mode is selected to weak blasting excavation, the depth of blast holes and the loading amount should be strictly controlled.

In the step 2, the preliminary tunnel support 11 comprises a preliminary tunnel steel frame 23 and net sprayed concrete, the preliminary tunnel support 11 is gradually constructed in the step excavation process, 4cm thick concrete is sprayed for sealing the surrounding rock in time after excavation, 8cm thick concrete is sprayed for sealing the face surfaces of the upper step 4 and the middle step 5 in time, and 10cm thick concrete is sprayed for the bottom of the step.

In step 2, selecting 3-5m for each step length; and (3) selecting 6-8m for the distance between the lower step 6 excavated in the step (2) and the upper step excavated in the step (3).

And (3) selecting the distances between the lower step 9 excavated in the step (3) and the inverted arch 12 of the previous tunnel poured in the step (7), and the distances between the inverted arch 12 and the arch wall 13 of the previous tunnel poured in the step (7) to be 6-8 m.

In step 2, the removal of the temporary middle partition wall 10 of the tunnel is performed after the preliminary supporting construction of the main structure of the tunnel body is completed and stabilized.

In step 7 and step 8, in the construction process, monitoring measurement is enhanced, the structural stability of the tunnel body is analyzed, a basis is provided for adjustment of support parameters of the advance tunnel 1 and the backward tunnel 2 and pouring of an arch wall of the advance tunnel, and monitoring points are distributed as shown in fig. 4.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.