黏土条件下隧道稳定率分析

Stability Degree of Excavation in Clay Soil

隧道稳定是岩土工程领域一个重要问题。分析了岩土工程中常用来评价稳定性的安全系数,引出了隧道稳定率的概念;给出了几种不同情况下隧道稳定率的表述形式,即不考虑土重影响时的稳定率,考虑土重影响时的稳定率和隧道支撑力的稳定形式;以Davis提出的一个变量隧道垮落模型为例,构建块体速度场和受力分布图,根据功能原理,推导了基于一个变量的单圆形隧道稳定率。根据现场实测数据,得出现场稳定率;根据分析计算,得出理论稳定率。针对3种不同形式的稳定率进行了分析,当现场稳定率的值大于理论值时,隧道已垮落;当现场稳定率的值等于理论值时,隧道处于临界垮落状态;当现场稳定率的值小于理论值时,隧道处于稳定状态;由此,可根据不同情况,利用不同形式的稳定率表达式评价隧道是否稳定。

Stability of the tunnel is a very important issue in geotechnical engineering.First the factor of safety is introduced into the assessment of stability in the geotechnical engineering,and then the concept of stability degree is defined.Various kinds of the stability degrees of tunnel are discussed,including those with and without consideration of earth weight and that related with support strength of tunnel.Then with a variable tunnel model of failure proposed by Davis＇s as an example,the block body velocity field and the stress distribution are obtained,based on the work-energy theorem,and the stability degree is calculated.According to measured data on the site,the site stability degree is obtained.The theoretical stability degree can be obtained by analysis.These three different stability degrees are compared when the value of site stability degree is greater than the theoretical value,then the tunnel would fail;when the value of site stability degree is equal to the theoretical value,then the tunnel is in a critical failure state;when the value of site stability degree is smaller than the theoretical value,then the tunnel is in a stability state.According to different circumstances,with the use of different expressions of the stability degree of the tunnel,the tunnel stability can be assessed.