A method for determining tunnel limit displacement

Abstract

The invention discloses a method for determining tunnel limit displacement. The method comprises the steps of establishing a finite element numerical model; determining main mechanical parameters of the surrounding rock; wherein the tunnel site region ground stress adopts a self-weight ground stress field; determining a key monitoring point; simulating an excavation and support process; checking model rationality; dividing the surrounding rock strength by the reduction coefficient, and simulating an excavation and support process; if the calculation does not meet the stop condition, returningto the previous step and increasing the reduction coefficient until the stop condition is met; extracting the key point displacement of the previous reduction step reaching the stop condition; and theobtained key point displacement is multiplied by a measurable coefficient to serve as tunnel limit displacement for monitoring, measuring and early warning. The limit state and the limit displacementof the tunnel surrounding rock are obtained through surrounding rock strength reduction, operation is easy, reliability is achieved, cost is low, the influence of factors such as the tunnel section type, the buried depth, the construction procedure and the supporting structure on the tunnel limit displacement can be considered, and necessary technical support is provided for researching the tunnel limit displacement and establishing a monitoring and measuring early warning standard.

Description

technical field [0001] The invention relates to a method for determining the limit displacement of a tunnel, which belongs to the technical field of tunnel monitoring and measurement. Background technique [0002] The monitoring and measurement of surrounding rock deformation during tunnel construction is an important part of NATM tunnel construction technology. The monitoring results of tunnel surrounding rock deformation can not only be used to feed back and correct support parameters, but also have great significance for evaluating the stability of surrounding rock and ensuring the safety of on-site personnel and equipment. The stability analysis of the tunnel surrounding rock based on the displacement of the tunnel surrounding rock is to judge the stability of the tunnel surrounding rock by comparing the displacement of the surrounding rock measured on site with a certain limit displacement. Determination of limit displacement of rock and support system. At present, th...

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Problems solved by technology

However, the above methods have certain limitations: theoretical analysis needs to simplify the tunnel section, geological conditions and other factors, and it is difficult to consider the influence of non-circular section, complex geological conditions and specific construction methods on the tunnel limit displacement; site investigation requires The actual measurement data of the tunnel in the damaged state is counted, but it is extremely difficult to collect the tunnel monitoring measurement data in the damaged state; the on-site damage test of the tunnel and the indoor model test are relatively reliable methods to obtain the ultimate displacement of the tunnel, but these tests are expensive and limited by The cost factor is difficult to carry out many times, and the research can only be carried out on some typical conditions such as surrounding rock state, section shape, support type and construction method, and the results are difficult to apply to the real situation of the tunnel site

[0004] The above technologies do not give much consideration to how to determine the ultimate displacement of the tunnel in consideration of the actual section of the tunnel, the state of the surrounding rock, the support structure and the construction process. specific guidelines

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