走滑断层地震地表断裂位错估计方法研究

为对一次地震中可能造成的地表断裂位错作出较准确的估计，采用拟静力弹塑性有限元方法，分别对覆盖土层为粉质黏土和黏土情况下，走滑断层引发的地震地表断裂进行了数值模拟分析。根据历史震害数据回归拟合的震级M与基岩位错 的关系式以及数值计算结果，建立了震级M与地表位错 的关系式。公式中考虑了土层厚度H对地表位错 的影响，而不仅仅局限于根据震级M的大小通过统计公式来估算地表断裂位错 。结果表明，走滑断层引发的地震地表断裂位错不仅与震级的大小有关，还与土层厚度和土层性质有关；在相同震级作用下，随着土层厚度的增加，地表位错逐渐减小；在相同震级和相同土层厚度下，上覆土层为粉质黏土时产生的地表位错要大于上覆土层为黏土时产生的地表位错；根据拟合的公式估计出不同震级情况下可不考虑走滑断层影响的临界覆盖土层厚度值，有助于提高活动断裂地震危险性评估工作的可靠性。

Estimate method of dislocation to seismic surface rupture under strike-slip fault

In order to estimate seismic surface rupture dislocation more accurately, the finite element method of pseudo-static elastoplasticity is used for numerical simulation to seismic surface rupture by strike-slip fault. In the numerical model, the two cases of silty clay and clay are discussed respectively. According to the relationship between magnitude M and bedrock dislocation Dbedrock which is regressed and fitted based on historical earthquake damage data and numerical calculation results, the relationship between magnitude M and surface dislocation Dsurface is set up. In the formula, the influence factor of soil thickness H is considered, and not just estimate surface rupture dislocation depending on magnitude by using statistical formula. The results show that: seismic surface rupture dislocation under strike-slip fault relates not only to magnitude, but to soil thickness and soil properties; Surface dislocation decreases gradually with the increasing of soil thickness under the same magnitude; Surface dislocation of silty clay is larger than that of clay under the same magnitude and soil thickness; The critical value of soil thickness without considering strike-slip fault is estimated based on the fitting formulas, and the result is helpful to improve the reliability of seismic risk evaluation of active fault.