A test device for cumulative damage of tunnel bottom structure under cyclic loading

Abstract

The invention discloses a test device for cumulative damage of a tunnel bottom structure under cyclic loading. Constraining forces around a specimen are provided by using a digital display jack to simulate the actual stress state of the tunnel bottom structure, a way of densely distributing springs at the bottom of the specimen is used to simulate a restriction effect of tunnel bottom surrounding rock for the bottom structure, and the upper part of the specimen is loaded through an MTS loading system to simulate the effect of train cyclic loading; cumulative damage characteristics of the specimen under the cyclic loading are tested by using a dynamic strain test system and a ceramic piezoelectric testing system. The method and device can simulate the influences of the surrounding rock of different levels by changing the stiffness of the springs at the bottom of the specimen, and further can quantitatively simulate the actual situations of local void or softening of the tunnel bottom surrounding rock through spring combinations of different stiffness and numbers, so as to solve the application problem of bottom constraint when the existing test method and device cannot consider unevenness of the local void or softening at the bottom of the specimen.

Description

Technical field [0001] The invention relates to a test device for cumulative damage of a tunnel bottom structure under a cyclic load. Background technique [0002] After a period of operation of the existing railway tunnels in our country, some of the tunnels have suffered from structural damage at the bottom of the tunnels, mud and mud, etc., which seriously affected the safety of tunnel operation. The durability and stability of the tunnel bottom structure are of great significance to the long-term safety of railway tunnels (especially high-speed railway and heavy-duty railway tunnels). Therefore, it is necessary to conduct in-depth experimental research on the cumulative damage and long-term dynamic characteristics of the tunnel bottom structure under the cyclic load of the train. [0003] At present, the domestic and foreign test methods for accumulative damage of specimens under cyclic loading mainly include uniaxial tensile test, uniaxial compression test, test under pure be...

AI Technical Summary

Problems solved by technology

[0007] In order to solve the technical problem that the cumulative damage characteristics of the tunnel bottom structure under the current train load cannot be truly reflected in the test, the present invention provides a cumulative damage under cyclic load that can also be quantified in a single direction by applying uneven restraint pressure test device

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