岩溶场地地震作用下加速度变化研究

Research of acceleration change in karst area by earthquake

为研究岩溶场地地表地震动参数变化规律,运用正交试验的基本理论和方法步骤,通过正交试验设计单一土洞在4种因素(土洞直径、覆盖土层厚度、土洞深度以及土体动弹性模量)变化下地表加速度时程的变化。选取了正交表分析设计32组数值试验的方案,建立400m×400m的场地有限元模型计算,并运用MATLAB软件对上述32组有限元试验计算结果进行二次回归分析,得到场地地表地震动与各主要影响因素的关系式。分析得到:土洞的直径d对场地的地表峰值加速度影响最大,其次是覆盖土层厚度H和土体动弹性模量E,影响较小的是土洞的深度h;且当仅有1个自变量时分别随着土洞直径d、覆盖层厚度H和土体的动弹性模量E变化时为开口向下的二次函数,随着土洞中心点的深度h变化时为开口向上的二次函数。

For the research of karst area surface change law of earthquake ground motiong parameters by using the basic theory and method of the orthogonal experiment steps, through the orthogonal experiment design single hole in the four factors （ soil hole diameter, thickness of covering soil layer, soil hole depth and the soil dynamic modulus of elasticity） changes the acceleration time history of the earthg surface. Selected the orthogonal table ofto analysis and design of 32 set of numerical test plan, set up the venue of the 400m by 400m finite element model, and using the MATLAB software to the above 32 groups of quadratic regression analysis based on the finite element calculation results, the surface of the ground motions and the relation between the main influence factors. Analysis： the soil hole diameter d had the greatest influence on the ground surface peak acceleration, followed by the soil and the cov- eting soil thickness H of dynamic elastic modulus E, Less affected the depth of the soil hole is h ; And when there is only one independent variables respectively as the soil hole diameter d, covering soil layer thickness H and the dy- namic modulus of elasticity E changes quadratic function for opening downward, with the change the depth of the soil hole center h for the opening up of the quadratic function.