跨地裂缝地铁隧道竖向地层压力计算方法探讨

 地裂缝是一种特殊的地质灾害，其活动方式主要表现为地层的垂直错动并引起地表破裂，对工程建(构)筑物危害十分严重。地裂缝活动引起其两侧地层的差异沉降会在跨越地裂缝带的地下结构上产生不同于一般地层的附加应力(压力)，导致地下结构纵向拉裂甚至直接剪切或剪断破坏。如何求解地裂缝环境下地层有效荷载是跨越地裂缝带地下工程结构设计的关键。以西安地铁穿越地裂缝带为研究背景，通过对浅埋暗挖地铁隧道穿越地裂缝带大型物理模型试验作用机制及数据的分析，建立地裂缝活动环境下地铁隧道与周围土体荷载结构模型，用于计算跨地裂缝段地铁隧道结构上覆竖向地层压力的大小。探讨性地提出基于地层挟持作用的地裂缝荷载计算方法，并与基于马斯顿原理的地裂缝荷载计算法及规范法进行对比，最后与模型试验结果进行对比验证与讨论，认为基于地层挟持作用地裂缝荷载计算法是计算跨地裂缝地段地铁隧道结构上覆地层土压力的有效方法，该方法对于地面沉降地裂缝发育区地铁隧道及城市地下工程设计具有重要指导和参考价值。

Calculation of vertical strata load of metro tunnel crossing ground fissure zone

Ground fissure is a kind of special geological hazard resulting in the vertical dislocation of strata and ground surface rupture，which may cause severe harm to engineering structures. Unlike the ordinary stratum stress caused by the soil gravity，the additional soil pressure induced by the ground fissure activity is different and often causes the underground structure to appear longitudinal tension crack and even direct shear failure. Determining the effective strata load in the zone with ground fissures is the key to the structure design of underground engineering crossing over the ground fissure belts. The metro in Xi?an crossing the ground fissures is studied in this paper. A load-structure model between the metro tunnel and surrounding soil in the active ground fissure environment was established on the basis of mechanism analysis and results of physical model test. The model was used to calculate the overlying vertical formation pressure of metro tunnel structure crossing ground fissures. A method of calculating the overlying load on the metro tunnel caused by the ground fissure activity was put forward and compared with the calculation method based on A. Marston principle and the method from the Code for metro design in China. The method was verified with the model test results.