土质隧道考虑时空效应的施工力学行为分析

Analysis on construction mechanics behavior of soil tunnel considering space-time effect

通过对膨胀土隧道开展动态施工力学的物理模型试验,得出各测点在洞室开挖和衬砌支护条件下的围岩应力—时间响应曲线。根据响应曲线对施工过程中围岩随时间及空间条件的变化而呈现的力学响应及行为表现进行分析,并将响应曲线的发展变化趋势按开挖和支护分为不同阶段,其中开挖过程分为零增长、微增长、急剧下降、缓慢减小和相对平稳5个阶段;支护过程分为急剧增长和缓慢下降2个阶段。此外,通过对隧洞竖向线及水平腰线上距洞室边缘不同距离测点的分析,表明随着距离的增大,由隧洞开挖导致的围岩应力释放量减少,释放速率减缓,力学响应敏感度降低,衬砌支护对围岩力学特性的影响也逐渐减弱。

Based on the physic model test of dynamic construction mechanics of expansive soil tunnel, the wall rock stress-time responsive curves of each measuring points were gained under the conditions of tunnel excavation and lining construction. According to the response curves, the mechanical response and behavioral ex-pression of wall rock based on the changes of time and space condition during construction process are analyzed, and the developing and changing tendency of responsive curves are divided into different stages according to tun-nel excavation and lining construction. The tunnel excavation process can be divided into five stages： zero in-crease, slight increase, dramatic decrease, slight decrease, relatively stable. Likewise, the lining construction process can also be divided into dramatic increase and slight decrease. Besides, through the analysis of measuring points with different distance from the tunnel chamber edge and local on vertical and horizontal line, it is indica-ted that with the increase of distance, the magnitude of wall rock stress release will reduce. At the same time re-lease rate will drop and the sensitive of mechanical response will decrease because of tunnel excavation. Mean-while, the impact that lead by lining construction for mechanical properties of wall rock will weaken gradually.