A combined testing method for loose rings in soft rock tunnels with high ground stress

Abstract

The embodiment of the present invention provides a joint test method for loose circles of high ground stress soft rock tunnels, comprising: selecting the area to be tested, reciprocatingly testing the range of loose circles of surrounding rocks by geological radar detectors, and recording as the first test result S 1 ; According to the first test result S 1 , to drill the area where the geological radar test has been carried out, and the drilling depth satisfies S 1 +2 meters; use a single-engine double-receiver acoustic logging tool to test the loose ring of the borehole, and record the second test result S 2 ; Compare and judge the first test result S 1 and the second test result S 2 Whether it is similar; if it is similar, it is determined that the loose circle test in this area is completed; if not, extend the drilling depth to S 1 +4 meters, and install a multi-point displacement meter in the borehole to record the third test result S 3 ; Judging the first test result S 1 with the third test result s 3 is similar, or the second test result S 2 and the third test result S 3 Is it close.

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