基于模型试验的桥基岸坡岩体变形分区研究

Study on deformation division of bridge foundation slope based on model test

变形是控制桥基岸坡稳定性的重要因素。以西南某高速公路跨越金沙江大桥为依托,建立室内边坡模型实验及有限元模型来研究不同大小桥梁荷载作用下边坡的位移响应机制。通过定义位移敏感性系数为边坡内部各点处位移荷载曲线的平均曲率,将边坡内部划分为3种不同敏感程度区域,并与模型实验中测量得到的位移数据进行比较分析。然后基于不同荷载等级下敏感区域分布来研究桥基下方软弱夹层的存在对边坡变形的影响。结果表明:在桥梁荷载作用下,承台前缘的部分有向边坡体外部挤出的趋势,在承台处及后缘处需要考虑竖向的沉降问题。当桥梁荷载超载达到十倍设计桥梁荷载时,承台周围的位移变形已经不可忽视。下部软弱夹层的存在使桥梁荷载对边坡的影响向深处及边坡前缘发展。当桥基荷载足够大时,边坡有整体破坏的趋势。

Deformation is a key factor to control the rock stability of bridge foundation slope.In the present paper,both the laboratorial slope model and the FEM models were built to analyze the displacement response under different bridge load.The sensitive coefficient was defined as the average curvature of displacement-loading curve to partition the slope into three levels of sensitive areas and this concept was confirmed by the displacement data from laboratorial slope model test.Then,the influence of the weak layer under the bridge foundation to the deformation of slope was studied based on different distributions of sensitive areas under different loading levels.Results show that the leading edge of bearing plat⁃form tends to be extruded out of the slope under the bridge load while the settlement occurred both in front of and under⁃neath the platform.When the bridge load reaches tenfold designed load,the deformation around the bearing platform can⁃not be ignored.And the existence of weak layer allows the bridge load to affect deep areas and leading edge of the slope.When the bridge load is extremely high,the slope tends to fail.