分岔隧道模型试验与数值模拟超载安全度研究

超载试验能得到隧道的超载安全度，通过大型地质力学模型对分岔隧道进行了超载试验，模拟了分岔隧道在不同侧压系数下围岩的变形、应力分布和破坏情况。同时，应用三维数值分析软件对模拟区域进行了模拟。模型试验和数值模拟结果分析表明，随着侧压系数K的增加，分岔隧道的侧向位移增加，拱顶位移由向下变为向上；当侧压系数为K=3．5时，应力达到极限；当侧压系数K≥4．0时，位移突变，最终最大位移达到100mm；塑性区骤增，隧道拱项围岩开始开裂，且有块体掉落。分岔隧道的拱顶和两帮是最易破坏的区域，隧道超载安全度为3．5。

Model test and numerical simulation of overload safety of forked tunnel

Tunnel overloading safety can be gained by overloading experiment. In this paper, the overloading stability of forked tunnel is researched using 3-D geomechanical model test. The displacements, stress distribution and failure of surrounding rock are analyzed. And the model test is simulated by 3-D numerical method (FLAC3D) also. Model test result and numerical simulation result analysis shows that the side displacements increase and vault displacement vector changes from downwards to upwards with the side-pressure coefficient K. The stress of key points achieve high-point at K=3.5; the displacement changes suddenly when K≥ 4.0 and the maximum final displacement achieve 100mm. The plastic zone increases suddenly and surrounding rock at vault begin to crack and fall when K≥ 4.0. Test and numerical result shows that vault and side of forked tunnel are easy to fracturing; the overloading safety degree is 3.5.