高地应力软岩大变形隧道稳定性判据研究

围岩是隧道稳定性控制的主要对象,针对铁路隧道建设中高地应力软弱围岩的重大理论与实践难题,本文开展了理想连续介质条件下,围岩塑变形加速发展或塑性应变突变的稳定性极限状态研究。提出:(1)开挖过程中应充分发挥围岩的自承能力,允许围岩发生一定程度的塑性变形,但不能因过大变形让围岩进入松动状态,以保持围岩的稳定性;(2)当围岩塑性过程发展到塑性应变突变或变形加速发展时,围岩材料将进入塑性流动状态。此时,围岩因过大变形而松动,扰动后极易失稳、坍塌。(3)近区围岩塑性流动松动、深部为连续介质条件下,高地应力软岩大变形隧道稳定性的理论分析与判据方法有待深入研究。

Research on Stability Criterion of Tunnel with Large Deformation in High Ground Stress Weak Rock

Surrounding rock is a main object to control the tunnel stability.For the important theories and practical problems of high ground stress weak rock in the construction of railway tunnel,the research on the stability limit state of accelerated development of plastic deformation or sudden change of plastic strain of surrounding rock is carried out under conditions of ideal continuous medium.It is put forward that:(1)Self-supporting capacity of surrounding rock should be fully played during excavation,and the plastic deformation should be allowed for the surrounding rock to a certain extent,but the surrounding rock cannot be loosened due to excessive deformation,so as to maintain the stability of the surrounding rock.(2)When the plastic process of surrounding rock develops to the sudden change of plastic strain or the accelerated development of deformation,the materials of surrounding rock will go into the state of plastic flow.Meanwhile,the surrounding rock is getting loose because of excessive deformation so that it is very easy to lose stability and collapse after disturbance.(3)When the plastic flow of surrounding rock in near region is loose and the deep part is continuous medium,the theory analysis and criterion method of the stability of tunnel with large deformation in high ground stress weak rock need to be further studied.