CROSS REFERENCE TO RELATED APPLICATIONS

The application claims priority to Chinese Application No. 202011132887.1, filed on Oct. 21, 2020, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The disclosure relate to the technical field of tunnel construction, in particular to a tunnel adaptive lining structure in complex environment and a construction method thereof.

BACKGROUND

A hydraulic tunnel is an important part of conventional hydropower stations, pumped storage power stations and long-distance water conveyance projects. Whether the lining structure design is reasonable is related to the success or failure of the whole project. Hydropower stations, especially pumped storage power stations, generally have high internal water pressure in water conveyance tunnels in order to meet the water head required for power generation. For example, the maximum internal water head of the diversion tunnel of Yangjiang Pumped Storage Power Station under construction in China reaches 800 m. At the same time, these projects are located in deep buried strata, and are also faced with high external water pressure in the occurrence environment. For example, after the water conveyance tunnel of Jinping Level-Two Hydropower Station in China is blocked for nearly 5 km, the average groundwater pressure for many years is measured to be 10.22 MPa; the external water pressure of the diversion tunnel of Tianshengqiao Level-Two Hydropower Station is measured to be 3 to 4 MPa. At the same time, there are inevitable weak strata, local faults and high geothermal tunnel sections in the stratum through which the long-distance and large-depth water conveyance tunnel passes. With the long-term operation of the project, the underground water level accumulates and the water head rises in the rock mass. These projects are bound to face high internal water, high external water pressure and even high internal and external water alternation during the operation period and unloading maintenance period, which poses a great challenge to the rational design of lining and structural safety. In addition, the loads caused by creep deformation of the surrounding rock and dislocation deformation of faults will seriously threaten the safety of lining during long-term operation. During the long-term operation period, the high geothermal surrounding rock is conducted, so that the lining has the inside and outside differences in temperature, which is easy to cause temperature difference stress, leading to the cracking and damage of the lining, and then losing the original function of the lining.

At present, the main types of hydraulic tunnel lining comprise reinforced concrete lining, steel lining and pre-stressed lining. These structure types can deal with simple high internal water or high external water pressure operating environment, but there are still many insurmountable problems when dealing with high internal and external water alternation, such as the transition stage between operation period and unloading period. At the same time, the long-term creep deformation load of the surrounding rock and the temperature load of the high geothermal surrounding rock are not considered enough, which cannot deal with the security threat of weak stratum and high geothermal surrounding rock to lining.

SUMMARY

To solve the above technical problems, the disclosure provides a tunnel adaptive lining structure in complex environment and a construction method thereof, so as to solve the safety problem of the concrete lining structure under high internal water pressure, high external water pressure, large convergence deformation of the surrounding rock with high ground stress and high geothermal environment, so that the lining is in an internal and external compression state, giving full play to the advantage of high compressive strength, and avoiding problems such as concrete cracking resulted from tensile stress in the lining caused by uneven stress on the internal and external walls.

To achieve the above object, the disclosure provides the following solution.

The disclosure provide a tunnel adaptive lining structure in complex environment and a construction method thereof, comprising a lining, a pressure regulating layer and a connecting cylinder; wherein the pressure regulating layer is provided between the lining and a surrounding rock; and the connecting cylinder is provided in the tunnel and runs through the top of the lining.

Preferably, the pressure regulating layer comprises a plurality of pressure regulating chambers, and adjacent pressure regulating chambers are communicated with each other through connecting pipes of the pressure regulating chambers; the outer side of the pressure regulating chamber is in contact with the surrounding rock, and the inner side of the pressure regulating chamber is connected with the outer wall of the lining.

Preferably, the pressure regulating chamber is made of flexible high-pressure resistant material.

Preferably, the connecting cylinder is communicated with the pressure regulating layer through an internal water connecting pipe.

Preferably, two one-way valves are provided in the connecting cylinder, and the two one-way valves are provided in opposite directions; the upper ends of the two one-way valves are communicated with each other through a first branch pipe, and the first branch pipe is communicated with the internal water connecting pipe.

Preferably, a water collecting port is provided at the top of the connecting cylinder, and the water collecting port is communicated with the surrounding rock.

Preferably, a one-way valve is provided in the connecting cylinder, and the one-way valve is used for communicating the interior of the lining with the surrounding rock.

The disclosure further discloses a construction method of the tunnel adaptive lining structure in complex environment, comprising the steps of:

step 1, making pressure regulating chambers with corresponding sizes according to the size of a tunnel, so that the pressure regulating layer consisted of a plurality of pressure regulating chambers covers the inner surface of the surrounding rock;

step 2, fixing the pressure regulating chamber on the surrounding rock of the tunnel, and connecting the connecting pipes of the pressure regulating chambers with each other;

step 3, installing and fixing the connecting cylinder between the top two pressure regulating chambers;

step 4: repeating the above steps 2 and 3, and installing a plurality of circles of pressure regulating chambers according to the length requirements;

step 5: regulating the pressure value of the one-way valve and installing;

step 6, pouring the lining and finishing.

Compared with the prior art, the disclosure has the following technical effects.

The tunnel adaptive lining structure in complex environment and the construction method thereof in the disclosure are simple in structure, reasonable in design and convenient for efficient construction; it can deal with engineering problems such as lining cracking caused by high internal water and high external water in the tunnel, and can ensure the safety of tunnel lining in different periods; it not only enriches the structural types of hydraulic tunnel lining at present, but also effectively solves the problem that it is difficult to design the hydraulic high-pressure tunnel lining. At the same time, it has important application value and broad application prospect.

