宝兰客运专线洪亮营隧道滑坡成因机制探讨

Investigation on the formation and the mechanism of landslide in Hongliangying tunnel in the Baoji-Lanzhou passenger dedicated railway

根据现场调查和资料分析,认为洪亮营隧道滑坡属铁路隧道施工引发的工程滑坡,滑坡总方量约1.82×10~5 m^3,滑坡类型为黄土错落性滑坡,结合其形态和微地貌特征,可将滑坡从平面上划分为滑壁变形区、牵引滑体、主滑体、右侧次滑体和左侧次滑体5个区域.洪亮营隧道斜坡属自然形成的黄土斜坡,研究认为人类工程对斜坡的开挖扰动和路基施工中强夯形成的循环荷载是滑坡的主要引发因素.对滑坡的形成机理和过程可概括为4个阶段:开挖应力调整阶段、蠕滑剪切和拉裂阶段、锁固剪断和错落阶段、侧向分离扩展阶段,滑坡形成了垂直运动距离大于水平运动距离的错落性滑动,破坏了隧洞并封闭了洞口.采用有限元法对滑坡的变形进行了模拟,结果很好地反映了滑坡体内的变形场、应力场及破坏区分布,这样有助于更加客观、全面地对滑坡稳定性进行评判.

The landslides was classified to a typical scattered-type loess landslide with a total volume of some 1.82×106m3. Based on field investigation, according to its morphology and micro-geomorphic features, the landslide could be divided into 5 regions in the plane： the sliding wall deformation area, the traction sliding area, main landslide area, the right side sliding area and the left side sliding area. According to the kinetic characteristics of landslide, the formation mechanism of landslide could be summarized into four stages, namely the excavation stress adjustment stage, the creep shear and tensile breaking stage, the locking broken and scattered stage, the lateral separation and expansion stage. The study found out that the vertical sliding distance was greater than the horizontal distance which formed scattered sliding and blocked up the tunnel. The deformation were simulated with finite element model, the result reflected the deformation field, stress field and the distribution of broken areas well. The stability of the landslide could be calculated more objectively and more systematically.