隧道出洞口松散围岩塌方时空预测研究

Time and space prediction of collapse of loose wall rock at tunnel exit

塌方是山岭隧道出洞口经常发生的一类工程地质灾害,对其发生部位和时间预测一直是隧道工程技术难题之一。从应力传递概念出发,推导出隧道出洞口松散围岩失稳判据,得出塌方发生时进入松散围岩段的临界距离,可以对开挖过程中塌方发生可能性及其空间位置进行预测;并结合灰色理论和协同学理论,基于实测拱顶下沉数据,建立塌方时间预报的灰色-协同理论模型。然后,通过马鞍山隧道塌方事故对所推导的塌方位置判据和塌方时间预测模型进行有效验证,结果表明:计算出塌方的空间位置和发生时间与实际情况相吻合,说明推导的塌方空间位置判据和建立的隧道塌方时间的灰色–协同预测模型是合理可行的,且具有较高的预测精度和可靠性,可为其它隧道出洞口塌方预测提供参考和借鉴。

Collapse is one of engineering geological hazard that often occurs at mountain tunnel exit.The prediction of spatial position and occurrence time of the collapse is one of technical problems of the tunneling engineering.The instability criterion and critical distance in loose wall rock at tunnel exit when the collapse occurs are deduced based on the stress-transferring theory.These formulas can be used to forecast the possibility and spatial position of the collapse.At the same time,based on the measured data of vault crown settlement,a grey-synergetic prediction model is established by use of the grey theory and the synergetic theory.Then the instability criterion and the grey-synergetic prediction model are verified by the collapse which occurs in Maanshan tunnel of Zhuji-Yongjia highway.The results show that the spatial position and the occurrence time of the collapse predicted are consistent with the practical situations.It is feasible to use the deduced instability criterion and grey-synergetic theory to predict the spatial position and occurrence time of tunnel collapse.This prediction method has high accuracy and reliability,and it can provide references for the prediction of other collapses at tunnel exit.