Tunnel operation safety test method under external water pressure

Abstract

The invention relates to a test method for the operation safety of a tunnel under the effect of external water pressure, and aims to provide the test method for the operation safety of the tunnel under the effect of the external water pressure, in which the effect of high external water pressure is simulated by a method of pressurizing water, the stability of the tunnel during operation is evaluated, and the on-site situation is simulated as much as possible, so that disadvantages of a numerical simulation method and the boundedness of a standard computing method are overcome. The test method for the operation safety of the tunnel under the effect of the external water pressure is characterized by comprising the following steps: a, a test tunnel is excavated; b, a tunnel with the length which is one time larger than a tunnel diameter is selected as a support area in the middle part of the test tunnel, and is systematically supported, and another tunnel with the length which is one time larger than the tunnel diameter is selected as a nonsupport area; and the distance from the support area and the nonsupport area to two ends of the test tunnel is no less than the length which is one time larger than the tunnel diameter; and c, water pressurizing tests are respectively carried out in the support area and the nonsupport area, and systematic monitoring is carried out. The test method for the operation safety of the tunnel under the effect of the external water pressure disclosed by the invention is suitable for the hydraulic and water-power engineering.

Description

technical field [0001] The invention relates to a tunnel operation safety test method under the action of external water pressure, which is mainly applicable to water conservancy and hydropower projects. Background technique [0002] At present, many hydropower projects in my country adopt diversion-style development. In order to ensure the safety of tunnels during operation, they usually adopt deep-buried layouts. Under such conditions, diversion tunnels will have to withstand high external water pressure. The lining mainly plays the role of reinforcement, support and maintenance. The lining must work with the initial support of the rock mass to ensure the stability of the surrounding rock under the external water pressure. However, due to the severe cracking of the rock mass near the empty surface after the excavation of the tunnel, the development of the water-conducting structure, and the significantly higher permeability coefficient compared with the intact rock mass, t...

AI Technical Summary

Problems solved by technology

However, due to the severe cracking of the rock mass near the empty surface after the excavation of the tunnel, the development of the water-conducting structure, and the significantly higher permeability coefficient compared with the intact rock mass, the entire structural system will still bear huge external water pressure, and the overall safety will be severely restricted. test

[0003] In the deep buried environment, under high ground stress and high external water pressure, the long-term mechanical properties of the surrounding rock are completely different from those of the shallow buried project, which directly leads to the complexity and particularity of the lining load, and the long-term deformation of the existing surrounding rock The pressure generated also includes the external water pressure, and the long-term deformation pressure of the surrounding rock comes from both the expansion deformation caused by the aging fracture of the surrounding rock under high stress, and also from the additional deformation caused by the change of the effective stress in the surrounding rock caused by the change of the seepage field. Therefore, Traditional lining design concepts are no longer suitable for this complex situation, and the design methods in current codes may be difficult to fully evaluate and consider the effects of these extreme conditions

[0004] Although the numerical calculation method has made great progress compared with the past, due to the extreme complexity of the rock mass medium itself, its mechanical response, and the environment of occurrence, the numerical method cannot simulate the actual rupture of the surrounding rock on the one hand. Especially with the continuous evolution of the surrounding environment of engineering excavation, the actual impact on the project cannot be accurately evaluated; on the other hand, the seepage field inside the rock mass, especially the seepage characteristics of fractures, cannot be accurately reproduced, and the actual situation on site must be appropriately simplified , it is impossible to make an accurate evaluation of the safety of tunnel engineering

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