拟静力法公路路基结构抗震稳定性研究

Seismic Stability Analysis of Highway Subgrade Based on the Pseudo-static Method

中国是一个地震多发国家,特别是在中西部地区。地震的发生为偶然事件,发生频率并不大,但一旦发生所造成的破坏却是灾难性的,对于高等级公路也不例外。在以前的研究中,很少涉及路基填土的动力学特性以及路基结构在地震荷载作用下的稳定性,现行《公路工程抗震设计规范》对地震动力荷载作用主要是以区域地震烈度作为惟一的参考依据,没有考虑地震振动频率和地震持续时间等特性,因此无法真实反映路基结构在地震作用时的特性。针对以上问题,对路基结构的动力稳定性通过拟静力方法进行研究,对路基结构动力稳定性计算的拟静力公式进行了改进。对于挡土墙在地震荷载作用下挡墙加速度受到影响,在计算挡土墙土压力时考虑地震加速度分布系数的影响;对于路基通过引入加速度分布系数对地震惯性力进行了改进,并对路基边坡拟静力稳定计算的公式进行了改进。

China is an earthquake-prone country,especially in its central and western regions. Earthquake is an unexpected event,and while its occurrence is not frequent,it can be catastrophic, and its effect on high grade highways is no exception.Previous research has rarely addressed the dynamic characteristics of subgrade filing and the stability of subgrade structures under earth-quake loads.The effect on the seismic dynamic load,as documented by the current“Code for the Design of Highway Engineering,”typically uses the region of earthquake intensity as its only ref-erence.This code does not consider seismic vibration frequency,the duration of an earthquake,or other characteristics.Therefore it cannot accurately reflect the characteristics of a subgrade struc-ture during an earthquake.In this paper,we carry out research on the dynamic stability of the roadbed structure using the pseudo-static method.We have improved upon the quasi-static method with respect to its formula for the dynamic stability of the roadbed structure.The retaining wall acceleration,as affected by the seismic load,is considered in the calculation of the earth pressure on the retaining wall,as is the influence of the seismic acceleration distribution coefficient.With respect to the roadbed,we also improved the seismic inertia force by introducing the acceleration distribution coefficient.From these pseudo-static method modifications,the stability calculation formula for subgrade slopes was thereby improved.