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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。
Ground fissure is a kind of special geological disasters. The main mode of its activity is the vertical dislocation of the strata and the rupture of the earth’s surface, which endangered the construction (structure) of the project. The differential settlement of strata on both sides caused by the ground fissure activity will generate additional stress (pressure) on the underground structure across the ground fissure zone, which is different from the general formation, leading to longitudinal cracking of the underground structure or even direct shearing or shearing failure. How to solve the effective load of ground under ground fissure is the key to the structural design of underground engineering spanning the ground fissure zone. Taking the Xi’an metro crossing the ground fissure zone as the research background, through the analysis of the mechanism and data of the large-scale physical model test of the tunnel crossing the ground fissure in the shallow buried tunnel, the load structure model of the subway tunnel and the surrounding soil under the ground fissure activity environment is established, Used to calculate the size of the overlying vertical formation pressure of the subway tunnel structure in the ground fissure section. In this paper, the calculation method of ground fissure load based on stratum strangulation is tentatively put forward, and compared with the calculation method of ground fissure load and the normal method based on the Marston principle. Finally, the comparison and verification with the model test results show that based on the stratum holding effect The calculation method of ground fissure load is an effective method to calculate the earth pressure of the overburden in the metro tunnel structure in the section of ground fissures. This method has important guidance and reference value for the design of metro tunnel and urban underground engineering in ground subsidence ground crack development area.