Method for evaluating mechanical state of secondary lining of mining method tunnel

Abstract

The invention discloses a method for evaluating the mechanical state of a secondary lining of a mining method tunnel. The method comprises the steps that S1, a circumferential distance change value and a radial clearance convergence change value are measured, specifically, Delta L=L1-L0, and Delta R<ii>= Delta R1<ii>-Delta R0<ii>; S2, an inversion analysis of the internal force of a structure is carried out to obtain a calculated value Deltaof the change in the circumferential distance and a calculated value Delta<ii> of the change in radial clearance convergence; S3, the internalforce of the current state of the structure is obtained, when a value of Sigma(Delta L-Delta)<2>+K* Sigma(Delta R<ii>-Delta<ii>)<2> is smallest, iteratively calculating is carried out, the calculation ends, the structural internal force at the end is taken as the current structural internal force, and the calculated load is taken as the actual load currently born by the structure; and S4, the stress state of the structure is evaluated, and the internal force and load of the current structure are compared with the ultimate internal force considered in the design. According to the method for evaluating the mechanical state of the secondary lining of the mining method tunnel, the change of the arc length of the second lining is only need to be measured, and the radial displacement of characteristic points is only need to be monitored, the reliability is high, and the accuracy is high.

Description

technical field [0001] The invention belongs to the technical field of tunnel engineering, and more specifically relates to a method for evaluating the mechanical state of a secondary lining of a mining tunnel. Background technique [0002] Mine method tunnels are generally designed according to the principle of the New Austrian Method, and most of them adopt composite lining, which is composed of two parts: the primary support system of anchor + shotcrete and the secondary lining of concrete (or reinforced concrete). The external surrounding rock pressure is borne by the primary support, and the secondary lining is used as a safety reserve to bear the surrounding rock pressure transferred after the durability part of the primary support fails. However, in some tunnels with large deformation of soft rock and tunnels with significant rheological properties of the surrounding rock, the secondary lining needs to be designed to bear part of the pressure of the surrounding rock. ...

AI Technical Summary

Problems solved by technology

[0004] (1) Based on cost considerations, only a very small number of monitoring sections can be selected to install sensors, which cannot represent the health status of the entire tunnel, and the sensors are embedded in a point-like distribution on a single monitoring section, and only a few points can be measured The internal force of other points can only be obtained by speculation, and often cannot obtain the largest or most unfavorable internal force, so it cannot characterize the health status of a single tunnel section structure

[0005] (2) The pre-embedded components need to be buried during the tunnel construction period, which will have a great impact on the construction process; the embedded sensors inside the structure, due to the concrete pouring process, etc., the survival rate cannot be guaranteed to be 100%, and some point sensors will be damaged. Failure to obtain data; For high-speed railway tunnels, there are data transmission and testing components in embedded sensors, which are often located on the inner surface of the structure, which becomes a hidden danger to driving safety

[0006] (3) The lifespan of existing sensors is generally not high (about 10-15 years), which is far below the structural design life of 100 years, and long-term testing cannot be realized

Especially for tunnels where the secondary lining is used as a safety reserve, the secondary lining does not actually bear the surrounding rock pressure until the primary support components deteriorate, when the primary support begins to deteriorate and part of the surrounding rock pressure is transferred to the secondary lining , the sensor has often failed due to its own short life, that is to say, the sensor can no longer be used when monitoring is required

For soft rock large deformation tunnels and tunnels with significant rheological properties of surrounding rock, the surrounding rock pressure borne by the secondary lining also increases with time. This growth process often lasts for decades, and the existing sensor technology cannot achieve full process monitoring

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