基于JRC-JCR模型的桥址边坡渐进破坏分析

The Progressive Failure Analysis of Bridge Site Slope Based on the JRC-JCR Model

特大桥作为线性工程中的控制性工程,其桥址边坡的稳定性至关重要。由于陡峻山体往往发育有强卸荷裂隙,有潜在崩塌的可能。针对中国云南某一特大桥的桥址边坡稳定性问题,首先通过详细的地质调查确定其主要结构面特征,然后通过盒计数法得到结构面的分形维数,进而估算得到其结构面粗糙度系数并得到其抗剪强度参数。为了分析不同结构面系数以及陡倾卸荷裂隙倾角对稳定性的影响,建立有限元模型进行分析计算,最后给出了工程加固措施建议。其结果表明:①控制桥址边坡稳定性的关键结构面是一组陡倾的强卸荷裂隙以及一组缓倾的岩层层面;②研究区域结构面粗糙程度差异大,大部分较为粗糙;③有限元计算揭示出桥址边坡呈现典型的渐进破坏模式,若前方堆积体被移除,位移较大区域集中在陡坎前部;④随着粗糙度系数的减少以及陡倾结构面角度的加大,边坡由局部破坏转变成整体破坏;⑤要提高边坡的稳定性,必须控制陡倾结构面的进一步变形,并据此提出了相应的工程处置措施,结果表明处置后的边坡稳定性较好,可以进行下一步的工程建设。

As a control project in the linear engineering,the slope stability at the bridge site is very important.Because the strong unloading cracks often develop the steep mountain,the rock slope may lead to collapses.In view of the slope stability of a very large bridge in Yunnan,China,the main structural surface features are determined by the detailed geological survey,and then the fractal dimensions of the structural surfaces are obtained by the box counting method so that the roughness coefficient of the structural surface is estimated and the shear strength parameters are obtained.In order to analyze the influence of the different structural surface coefficients and steep dumping crack inclination angles on the slope stability,several finite element models are established for analysis and calculation,and some suggestions for engineering reinforcement are given.The results show that①the key structural planes controlling the slope stability at the bridge site are a group of steeply dipping strong unloading cracks and a group of gently dipping rock layers.②where are great differences in the structural surface roughness in the study area,most of which are relatively rough.③the finite element calculations reveal that the slope at the bridge site presents a typical progressive failure mode.If the front accumulation body is removed,the larger displacement area will be concentrated on the front of the steep ridge.④with the decrease in roughness coefficient and the increase in the steep structural surface angle,the slope failure model changes from the local failure to the overall failure.⑤it is necessary to control the further deformation of the steep-dip structural plane to improve the stability of the slope,and accordingly,the corresponding engineering disposal measures are put forward.The results show that the slope after disposal is of good stability,and the next step of engineering construction can be carried out.