渭河盆地构造应力场有限元数值模拟

Tectonic Stress Field of the Weihe Basin Using the Finite Element Method

依据渭河盆地活动构造特征及深部地层结构,以高精度GPS成果为边界条件,构建了区域三维有限元模型,并将模拟断裂运动性质及区域构造应力场,与地质地球物理的结果对比检验了模型模拟结果合理性。数值模拟结果更加精细地揭示出,陇县-马昭与韩城-华县断裂是渭河盆地中部与东、西部构造应力场差异的明显分界带,两条断裂夹挟的盆地中部区域是拉张应力(NW-SE向)集中带,陇县-马昭断裂以西则呈显著挤压应力(近E-W向),韩城-华县断裂以东以NE-SW向挤压应力为主;而礼泉-蒲城-合阳断裂又为盆地中部区域南、北两侧构造应力场差异分界带,断裂南侧较北侧呈现出更显著的NW-SE向拉张应力,该特征与断裂南侧构造地裂缝较北侧更为发育相对应。

Based on the tectonic and the deep geological strata structure of the Weihe Basin,the threedimensional（3 D）finite element dynamic model was established by using the high-precision GPS monitoring data as boundary conditions.We further compared the movement property of faults and focal tectonic stress field simulated by the 3 Dmodel with the geological survey results and focal mechanism.The results of numerical simulation detailed reveal that the Longxian-Mazhao and Hancheng-Huaxian faults are the obvious difference boundaries of the tectonic stress field.The middle part where between the two faults is the concentration zone of tensile stress in the NW-SE direction,on the west side of the Longxian-Mazhao fault presents significant compression stress in the E-W direction,while on the east side of the Hancheng-Huaxian fault mainly presents compression stress in the NE-SW direction.The Pucheng-Liquan-Heyang fault is also the obvious difference boundaries divided the tectonic stress field of the middle part of Weihe Basin into two parts.The south side shows more significant tensile stress in the NW-SE direction compared with the north side of this fault.That may be the tectonic dynamic mechanism for the ground fissure more developed in the south side than the north side.