Comprehensive extension assessment on tunnel collapse risk
Feng Zhang · Journal of Central South University(Science and Technology) · 2011
On the basis of statistical analysis on inducing factors of tunnel collapse,extension theory was applied to comprehensively evaluate tunnel collapse risk.The process is as follows.Flow chart of extension assessment was firstly established,and some main influencing factors with non-dimension preprocessed,including the classification of tunnel collapse,were used to set up classical and limited matter-elements.A simple dependent function was then used to determine factor weight for avoiding human subjective effect.The extension assessment model was used to evaluate collapse risk in Liuyanghe tunnel.The results show that the main inducing factors of tunnel collapse are weak rock and rainfall,for weak rock has very poor mechanical properties and rainfall will weaken rock mechanics and reduce the effective stress in surrounding rock.Thus it is easy to yield and become more instable.Collapse risk of Liuyanghe tunnel is high and some prevention measures must be taken such as putting emphasis on geology survey and monitoring during construction,and improving treatment capacity of collapse as well.