隐伏走滑断层错动致上覆土体破裂过程的研究

Study on Rupture Process of Overlying Soil Cause by Buried Strike-slip Fault Movement

通过建立三维数值模型,对隐伏走滑断层错动引发上覆土体的破裂过程进行了研究。利用应力Lode参数和等效塑性应变分别对断层错动过程中上覆土体的应力状态和破裂过程进行了分析,得到以下结论:在走滑断层错动过程中,地表土体应力状态从压缩→压剪→纯剪→拉剪→拉伸→拉剪→纯剪发生变化,随上覆土体埋深的增大,从压剪过度到拉剪应力状态,需要更大的断层位错量。对于相同的断层位错量,地表土体比埋深较大的土体产生更大等效塑性应变,因而地表土体先出现破坏变形。走滑断层的错动诱发地表土体出现“雁列式”破裂带,该破裂带与断层走向有一定夹角且向深部发展有限。

The rupture process of overlying soil caused by buried strike-slip fault is studied through making the three-dimensional numerical model.The stress state and failure process of overlying soil are analyzed by using stress Lode parameter and effective plastic strain during the movement of buried fault.The results of numerical simulation are summarized as follows:(1)The stress state of surface soil mass varies via compression→compression-shear→pure shear→tensile-shear→tesile→tensile-shear→pure shear during the movement of strikeslip fault.With the increase of the buried depth of the overlying soil,a greater amount of fault dislocation is required from compression-shear to tensile-shear stress state.(2)For the same amount of fault dislocation,the equivalent plastic strain of surface soil is larger than that of the soil of larger burial depth.Therefore,the failure deformation of surface soil firstly appears.(3)The fault movement of strike-slip fault induces the formation of echelon rupture zone,which has a certain angle with the fault strike and has limited depth.