In-situ test method and structure for deeply-buried soft-rock tunnel

Abstract

The invention provides an in-situ test method for a deeply-buried soft-rock tunnel. The in-situ test method comprises the first step of conducting sampling on an early-stage exploration tunnel to obtain distribution characteristics of in-situ stress fields, the second step of calculating and determining parameters of a simulation test tunnel, the third step of excavating and expanding a size effect transition section, the fourth step of calculating and determining positions of monitoring sections, the fifth step of arranging an observation branch tunnel and pre-burying monitoring instruments, the sixth step of excavating the simulation test tunnel, and the seventh step of conducting regular observation through the monitoring instruments. The invention further provides an in-situ test structure for the deeply-buried soft-rock tunnel. The in-situ test structure for the deeply-buried soft-rock tunnel is established according to the in-situ test method. The in-situ test structure comprises the simulation test tunnel, the early-stage exploration tunnel and the observation branch tunnel. By the adoption of the in-situ test method and structure, anisotropism and size effects of soft rock are truly represented, a large quantity of measured data and test information of the properties of surrounding rock can be obtained, the uncertain factors that deeply-buried soft rock are low in strength and prone to softening with water, and a high deeply-buried cave section is hard to form are avoided, the defects of existing monitoring methods and tests are effectively overcome, and a reliable data support is provided for analysis of stability of the tunnel.

Description

Technical field [0001] The invention relates to a testing technology for deep-buried soft rock tunnels, in particular to an in-situ testing technology for the size effect and anisotropy characteristics of deep-buried soft rock tunnels. Background technique [0002] At present, the tunnel project has been developing in the direction of growth and deep burial. More and more tunnel projects in all walks of life have experienced continuous large deformations and collapses in local tunnel sections due to high deep buried ground stress, weak surrounding rocks, and development of joints and cracks. Especially hydraulic and traffic tunnel projects generally have large excavation sections, and the section size effect makes the above phenomenon more obvious, causing great difficulties to the tunnel design and construction. Once the high ground stress is combined with the weak surrounding rock, the rock around the cave will be subjected to high ground stress after excavation, and the rock ...

AI Technical Summary

Problems solved by technology

[0003] At present, domestic and foreign research on soft rock tunnel engineering with high buried depth and large cross-section is still mainly focused on laboratory tests. However, due to the obvious anisotropy characteristics of soft rock and its low strength, the sampling and sample preparation process It is easy to be damaged by the influence of the external environment, so the actual response characteristics of soft rock in the field are very different from those in laboratory tests. It is necessary to carry out in-situ tests to grasp the deformation of surrounding rock in deep soft rock tunnels However, excavating a simulated test tunnel with the same size as the original tunnel is not only expensive, but also difficult to meet the time requirements of the project. If the size is small, the surrounding rock failure phenomenon under high stress conditions cannot be fully exposed. , unable to strongly support the research on the problem of soft rock cavitation

Images