Joint test method for high ground stress soft rock tunnel loose circle

Abstract

The embodiment of the invention provides a joint test method for a high ground stress soft rock tunnel loose circle, which comprises the following steps: selecting a to-be-tested area, testing the range of the surrounding rock loose circle in a reciprocating manner through a geological radar detector, and recording as a first test result S1; according to the first test result S1, performing drilling on the area where geological radar test is conducted, and the drilling depth meets S1+2 meters; adopting a one-transmitting and two-receiving acoustic logging instrument to carry out loosening circle testing on the drilled hole, and recording a second testing result S2; comparing and judging whether the first test result S1 is similar to the second test result S2 or not; if so, determining thatthe loose circle test in the region is completed; if not, extending the drilling depth to S1+4 m, installing a multi-point displacement meter in the drilled hole, and recording a third test result S3; and judging whether the first test result S1 is close to the third test result S3 or not, or whether the second test result S2 is close to the third test result S3 or not.

Description

technical field [0001] The invention relates to the field of tunnel construction, in particular to a combined testing method for loose rings of high ground stress soft rock tunnels. Background technique [0002] Several fault fracture zones are intertwined vertically and horizontally in the difficult and dangerous mountainous areas of Southwest my country, the tectonic movement is very strong, strong earthquakes occur frequently, and the rock mass joints and fissures in the area are extremely developed. The phenomenon of large deformation, the excavation process of the high ground stress soft rock tunnel is affected by the formation disturbance, and the regional weak and broken surrounding rock causes local stress release and the formation of loose circles. [0003] The applicability of the range of surrounding rock loose circle obtained through construction experience or theoretical derivation under multiple assumptions is not high, so the field test technology of loose circ...

AI Technical Summary

Problems solved by technology

[0004] Determining the scope of the loose circle after tunnel excavation is an important basis for rationally designing the tunnel support structure and evaluating the stability of the surrounding rock. Different small coal mine roadways for railway tunnels have larger construction sections and spans, which constitute a wider range of rock mass loosening. The ring test method is a single test method, and the reliability of the actual loose ring range measured is low, which affects the design of the support structure

[0005] In recent years, the technical means of on-site testing of loose rings has been continuously innovated. The existing testing methods are mainly divided into physical detection method and direct observation method based on different testing principles. However, there are still disadvantages in the test. The method is significantly affected by the integrity of the test hole or rock sample coring. In addition, the current test methods all use a single test technology, and the test results lack the mutual verification of multiple test technologies, and the test accuracy is still open to question.

Images