Safety evaluation method for tunnel anchorage

Abstract

The invention discloses a safety evaluation method for a tunnel anchorage. Long-term shear strength parameters of surrounding rock of the tunnel anchorage are used as a safety evaluation basis for thetunnel anchorage; the long-term shear strength parameters are measured according to the following steps: simulating engineering site surrounding rock, and preparing a tunnel anchor surrounding rock model test piece; establishing a shear strength relaxation curve of the test piece under different vertical loads through a constant-load consolidation drainage shear test; converting the shear strength relaxation curve into an lgt1/[tau] curve, and establishing a long-term strength equation of the shear strength of the test piece along with time change under different vertical loads; and selectinga required long-term strength equation under a vertical load, and determining a long-term shear strength parameter of the test piece, namely the long-term shear strength parameter of the tunnel anchor surrounding rock. According to the invention, the long-term shear strength parameter is adopted, so that the mechanical property of the rock mass under continuous shear load can be more reliably reflected, and the deviation between a test result and engineering practice is greatly reduced.

Description

technical field [0001] The invention relates to a safety evaluation method for tunnel anchorage, which belongs to the technical field of bridge engineering. Background technique [0002] At present, the anchorage methods of suspension bridges mainly include gravity anchorage, tunnel anchorage, composite anchorage of gravity anchor or tunnel anchor + anchor cable, and composite anchorage of reinforced concrete and rock mass. Tunnel anchors are often used in canyon areas where the rock mass is relatively hard and complete, and most of the tension in the main cable is transmitted to the surrounding rock through the anchor plug body. The bridge will generate a huge pulling force to act on the anchorage, and the function of the anchorage is to transmit this huge pulling force to the foundation. At this time, the anchorage will have a huge shearing effect on the surrounding rock mass, and the shearing The force will continue to act during the safe service life of the bridge, caus...

AI Technical Summary

Problems solved by technology

In-situ experiments to test the shear strength parameters of surrounding rocks are usually troublesome, especially in areas with soft geology, in-situ experiments are even more difficult to carry out

Moreover, the existing method for determining the surrounding rock parameters is to conduct direct shear tests, and use the instantaneous shear strength parameters of the surrounding rock to evaluate the safety of the tunnel anchorage. Therefore, this value is usually large, resulting in a large deviation between the results of the indoor test and the actual project, and it is impossible to accurately judge the safety of the project, so that it is impossible to take safety measures in time

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