CN111058482B

CN111058482B - Construction method suitable for rapid precipitation of arch bottom of open-cut tunnel

Info

Publication number: CN111058482B
Application number: CN202010130640.XA
Authority: CN
Inventors: 洪永佳; 周志强; 朱显镇; 叶坚波; 张乃烊; 赵晗
Original assignee: Fuzhou Planning And Design Institute Group Co ltd
Current assignee: Fuzhou Planning And Design Institute Group Co ltd
Priority date: 2020-02-26
Filing date: 2020-02-28
Publication date: 2022-03-08
Anticipated expiration: 2040-02-28
Also published as: CN111058482A

Abstract

A construction method suitable for rapid precipitation of an arch bottom of an open-cut tunnel comprises the following steps: 1) excavating a tunnel to the bottom of an inverted arch; 2) a dewatering well is drilled at the bottom of the inverted arch; 3) continuously pumping water and excavating a front soil layer by using an inverted arch trestle; 4) verifying the water level and the bearing capacity of the bottom of the inverted arch of the newly excavated tunnel, pouring the inverted arch if the use requirement is met, and newly digging a dewatering well and pouring the inverted arch of the previous well point if the use requirement is not met; 5) and (5) circulating the step 3) and the step 4) until the tunnel construction is completed. By adopting a tunnel bottom precipitation method, the underground water at the periphery of the bottom of the inverted arch of the tunnel is quickly collected, and the bearing capacity of the peripheral un-excavated soil body is improved; the depth of the dewatering well is greatly reduced, so that the construction efficiency is improved, and the material cost is saved; by observing the precipitation effect, the diameter and the depth of the precipitation well for subsequent construction are dynamically adjusted, the manufacturing cost is saved, and the precipitation efficiency of the precipitation well is improved; the construction of precipitation well and tunnel construction are carried out in step, improve the efficiency of construction for the tunnel construction progress.

Description

Construction method suitable for rapid precipitation of arch bottom of open-cut tunnel

Technical Field

The invention relates to the field of tunnel construction, in particular to a construction method suitable for rapid precipitation of an arch bottom of an open-cut tunnel.

Background

With the rapid growth of the economy of China, the existing basic transportation facilities cannot meet the requirements of the people for going out at present, so that the construction of the basic facilities is greatly promoted by the nation. In order to meet the requirements of short mileage, straight line, high speed, comfortable riding and the like, the construction of the tunnel is the best choice for crossing mountainous and hilly areas.

Tunnel construction methods can be divided into underground excavation and open excavation. When the inverted arch is constructed in the open trench tunnel section, soil body at the bottom of the tunnel is softened by soaking water due to the existence of underground water, so that the bearing capacity of the soil body is seriously reduced, and the requirement on the bearing capacity during the construction of the inverted arch of the tunnel cannot be met. Therefore, how to reduce the underground water of the inverted arch section to meet the bearing capacity requirement of the tunnel structure becomes a problem which is troublesome and urgently needed to be solved in the open cut tunnel construction process.

At present, precipitation is carried out by digging precipitation wells at two sides of a tunnel body, but the method has the defects of high manufacturing cost and low precipitation efficiency, and the requirement of rapid and safe construction of open cut tunnels is difficult to meet.

Disclosure of Invention

The invention aims to provide a construction method suitable for rapid precipitation of an arch bottom of an open-cut tunnel, which can reduce the manufacturing cost and improve the precipitation efficiency on the premise of meeting the construction requirement of an inverted arch.

The technical scheme of the invention is as follows: a construction method suitable for rapid precipitation of an arch bottom of an open-cut tunnel comprises the following steps:

1) excavating a tunnel to the bottom of an inverted arch;

2) digging a dewatering well in the soil layer at the bottom of the inverted arch and dewatering at a vacuum well point;

3) continuously reducing water and arranging an inverted arch trestle to operate the soil body in front of the dewatering well;

4) verifying the water level and the bearing capacity of a soil layer at the bottom of the inverted arch of the newly excavated tunnel, pouring the inverted arch if the use requirement is met, and newly digging a dewatering well and pouring the inverted arch of the previous well point if the use requirement is not met;

5) and (5) circulating the step 3) and the step 4) until the tunnel construction is completed.

Further, in the step 2), the depth of the dewatering well is determined according to the water content of the local soil layer and the underground water level.

Further, in the step 3), the groundwater level is lowered to be at least 1m below the bottom of the inverted arch.

Further, in the step 4), inverted arch pouring, vacuum well point dewatering and soil body operation are carried out simultaneously.

Further, in the step 5), the precipitation effect of the precipitation well is recorded, whether the precipitation well can meet the tunnel precipitation requirement is judged, and the depth and the diameter of the subsequent precipitation well are dynamically adjusted.

Compared with the prior art, the invention has the following advantages: 1. pumping a dewatering well at the bottom of the tunnel, rapidly collecting underground water at the periphery of the bottom of the inverted arch of the tunnel, and improving the bearing capacity of peripheral unearthed soil body to meet the requirement of the bearing capacity; 2. by adopting the method of tunnel bottom precipitation, the depth of the precipitation well is greatly reduced, the construction efficiency is improved, the material cost is saved, and the effect of reducing the manufacturing cost is achieved; 3. the diameter and the depth of the dewatering well for subsequent construction can be dynamically adjusted by observing the dewatering effect, so that the manufacturing cost can be effectively saved, and the dewatering efficiency of the dewatering well can be improved; 4. the construction of precipitation well can go on with tunnel construction in step, can improve the efficiency of construction for tunnel construction progress.

Drawings

FIG. 1 is a cross-sectional view of a construction structure of the present invention;

FIG. 2 is a cross-sectional view of a conventional construction method;

FIG. 3 is a second step top view of the present invention;

FIG. 4 is a top view of a third step of the present invention (a longer tunnel has been excavated and the inverted arch trestle is omitted);

FIG. 5 is a top view of a fourth step of the present invention (beginning inverted arch casting);

FIG. 6 is a top view of a fifth step of the present invention (several inverted arches have been cast);

FIG. 7 is a top view of the fifth step of the present invention (newly pumping precipitation well);

FIG. 8 is a top view of a fifth step of the present invention (placing an inverted arch on an old dewatering well);

in the figure: 1-ground, 2-inverted arch, 3-dewatering well, 4-first slope, 5-first platform, 6-second slope and 7-inverted arch bottom soil layer.

Detailed Description

In order to make the aforementioned features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below, but the present invention is not limited thereto.

Refer to fig. 1-8.

In a preferred embodiment of the present invention, a construction method suitable for rapid precipitation of an arch bottom of an open cut tunnel includes the following steps:

1) directly excavating two back and forth tunnels to the bottom of the inverted arch;

2) a dewatering well 3 is drilled in the soil layer 7 at the bottom of the inverted arch, vacuum well points are used for dewatering, the positions of the dewatering wells of the two tunnels do not correspond to each other, and the influence range of the dewatering well is expanded;

3) continuously lowering the water, and setting an inverted arch trestle to dig the soil in front of the dewatering well, wherein the two are carried out simultaneously, so that the construction progress is accelerated;

4) verifying the water level and the bearing capacity of a soil layer at the bottom of the inverted arch of the newly excavated tunnel, pouring the inverted arch 2 when the use requirement is met, and newly digging a dewatering well and pouring the inverted arch of the previous well point when the use requirement is not met;

In this embodiment, in the step 2), the depth of the dewatering well is determined according to the water content of the local soil layer and the groundwater level, and the determination method is the same as that of the existing dewatering well depth calculation method.

In this embodiment, in step 3), the groundwater level is reduced to be at least 1m lower than the bottom of the inverted arch, so as to avoid the reduction of the bearing capacity of the soil layer due to groundwater leakage.

In this embodiment, in the step 4), the inverted arch pouring, the vacuum well point dewatering and the soil body operation are performed simultaneously.

In the embodiment, in step 5), the precipitation effect of the precipitation well is recorded, whether the old precipitation well can meet the tunnel precipitation requirement is judged, and the construction parameters (the depth and the diameter of the precipitation well) of the next precipitation well can be dynamically adjusted along with the precipitation observation condition of the previous precipitation well, so that the effect of saving the construction cost is achieved.

The method adopts the dewatering well construction and the tunnel construction to be carried out synchronously, greatly quickens the tunnel construction progress, saves the quantity of the dewatering wells on the premise of ensuring the dewatering effect, and preferably selects the parameters of the dewatering wells.

It will be apparent to those skilled in the art that the above-described embodiments of the present invention are merely preferred embodiments of the present invention, and various changes, modifications, substitutions and alterations can be made without departing from the spirit and scope of the invention.

Claims

1. A construction method suitable for rapid precipitation of an arch bottom of an open-cut tunnel is characterized by comprising the following steps:

1) excavating a tunnel to the bottom of an inverted arch;

2) a dewatering well is drilled at the lowest point of the soil layer at the bottom of the inverted arch, and vacuum well point dewatering is carried out;

4) verifying the water level and the bearing capacity of a soil layer at the bottom of an inverted arch of the newly excavated tunnel, pouring the inverted arch if the use requirement is met, newly digging a dewatering well at the position and pouring the inverted arch at the previous well point if the use requirement is not met, and simultaneously performing inverted arch pouring, vacuum well point dewatering and soil body operation;

5) circulating the step 3) and the step 4) until the tunnel construction is completed;

in the steps 2) to 5), recording the precipitation effect of the precipitation well, judging whether the precipitation well can meet the requirement of tunnel precipitation, and dynamically adjusting the depth and the diameter of the precipitation well for subsequent construction;

in the step 2), the depth of the dewatering well is determined according to the water content of the local soil layer and the underground water level;

in the step 3), the groundwater level is lowered to be at least 1m lower than the bottom of the inverted arch.