初始剪应力对软黏土地基地震灾变特性的影响

Region of seismic fortification intensity of 7 degrees or more widely distributes in China, so these foundations may be at risk from earthquake disaster. The initial shear stress often inevitably exists in the foundations because of the upper buildings. In present, insufficient researches have been done into the effect of the initial shear stress on the earthquake disaster characteristics of the soft clay foundation. Therefore, this project reveals the effect of the initial shear stress on the soft clay foundation dynamic disaster characteristics, through the dynamic test, theoretical analysis and numerical simulation. Firstly, we contrast and analyze the dynamic characteristics of soft clay fundation soil when the initial shear stress exist or not; Secondly, according to the result of soil dynamic tests and constitutive analysis, we estabilish the modified constitutive model and the parameter values of the dynamic strength by considering the influences of initial shear stress; Finally, we reveal the effect of the initial shear stress on the soft clay foundation catastrophe characteristics and propose seismic measures under earthquake load through numerical simulation, using the modified constitutive model, the test parameter values of the dynamic strength and dynamic strength criterion. It can be seen that the research results are of important academic significance to further enrich the soft clay foundation seismic analysis theory, and they can be applied in the seismic strengthening design of the soft clay foundation to reduce earthquake damage.

抗震设防烈度7度及以上地区在我国广泛分布，这些地区建筑物的地基可能会遭受地震灾害的作用。而对于许多建筑物地基而言，由于其上部建筑物的存在常常不可避免的会受到初始剪应力的作用。本项目针对初始剪应力作用下软黏土地基地震灾变特性研究的不足，通过动力试验、理论分析和数值仿真，揭示初始剪应力对软黏土地基动力灾变特性的影响。首先开展软黏土的动三轴试验，对比分析软黏土存在和不存在初始剪应力作用时的动力特性；其次根据动力试验结果和本构理论分析，建立考虑初始剪应力作用的软黏土修正本构模型；最后，采用所建立的修正本构模型和试验得到的动强度参数值、动强度准则，结合工程实例，通过数值仿真，揭示初始剪应力对软黏土地基在地震荷载作用下灾变特性的影响，提出存在初始剪应力软黏土地基的抗震措施。研究成果具有重要的学术理论意义，进一步丰富了软黏土地基抗震分析理论，且可应用于地基抗震加固设计，从而减轻地震对软黏土地基的破坏。

抗震设防烈度7度及以上地区在我国广泛分布，这些地区建筑物的地基可能会遭受地震灾害的作用。而对于许多建筑物地基而言，由于其上部建筑物的存在常常不可避免的会受到初始剪应力的作用。本项目针对初始剪应力作用下软黏土地基地震灾变特性研究的不足，通过动力试验和理论分析，揭示初始剪应力对软黏土地基动力灾变特性的影响。首先开展软黏土的动三轴试验，对比分析软黏土存在和不存在初始剪应力作用时的动力特性；其次根据动力试验结果和本构理论分析，提出了饱和粘土动应力-应变关系发展模型；最后，给出了工程设计和数值计算中所关心的饱和粘土强度参数的变化规律和动强度准则，揭示初始剪应力对软黏土地基在地震荷载作用下灾变特性的影响。研究成果具有重要的学术理论意义，进一步丰富了软黏土地基抗震分析理论，且可应用于地基抗震加固设计，从而减轻地震对软黏土地基的破坏。