Influences of stress dilation on shape of failure surface for shallow tunnels
For shallow tunnels of single-lane railway and four-lane road, numerical simulation using finite differential code was conducted. The mechanical behavior of loose rock masses was studied considering the influences of shear dilation on the shape of the failure surface for the shallow tunnels, and the break angles using numerical simulation was compared with those using the Rankines analytical solutions and design code. From the comparisons, it is found that the difference between the break angle by numerical simulation and the design code is small when the shear dilation angle is equal to 0, with the maximum relative difference being less than 0.2% in road tunnels. With the dilation angles increase, the loose plasticity zone area of surrounding rock reduces obviously,and the break angle increases gradually. When the dilation angle is equal to the internal friction angle, the materials follow associated flow rule, and the numerical solution of the break angle is larger than the analytical solution, with the maximum relative difference being greater than 16.7% in road tunnels. Therefore, associated flow rule leads to overestimating break angle, and the dilation angle has an important influence on the failure surface shape for shallow tunnels in the loose surrounding rocks.
shear dilatation shallow tunnel failure mechanism break angle
YANG Xiao-li(杨小礼) WANG Jin-ming(王金明)
School of Civil and Architectural Engineering, Central South University, Changsha 410075, China
国际会议
长沙
英文
293-297
2008-09-28（万方平台首次上网日期，不代表论文的发表时间）