岷江双线特大桥高边坡稳定性研究

成兰铁路岷江双线特大桥高边坡位于岷江地震带,该区域属于高烈度地震强震频发区,降雨量大且集中,不良地质分布广,在复杂环境因素的影响下,极其容易引起边坡滑坡。在研究现场工程地质情况的基础上,利用FLAC3D有限差分软件,建立三维边坡模型,进行天然、降雨、地震及降雨-地震耦合工况下的稳定性分析。研究结果表明,天然工况下安全系数为1.318,边坡处于稳定状态;降雨工况下,随降雨量的增加,雨水入渗和加载作用增强,位移高值区逐步扩大并逐渐向坡脚延伸,25 mm/d、35 mm/d及45 mm/d降雨条件下的安全系数分别为1.001、0.932、0.912;地震工况下边坡不稳定,坡腰中上部位移与加速度最大,为易滑坡区域;降雨-地震耦合工况下,坡腰中上部极其不稳定,且随降雨量增加,滑体位移及加速度均增大。

STUDY ON THE STABILITY OF HIGH SLOPE OF THE MINJIANG RIVER DOUBLE-TRACK BRIDGE

The high slope of Double-track Bridge on Minjiang River of Chenglan Railway is located in Minjiang River seismic belt, which is a high and frequent seismic region, with substantial concentrated rainfall and widespread unfavorable geology. Under the impact of the complicated environmental factor, it may give rise to the slope slide easily. In this paper, 3D slope mode is established with FLAC3D finite difference software based on the study on the geology of field engineering, and stability analysis in such working conditions as the natural rainfall, earthquake and coupling of rainfall and earthquake. According to the results, the safety coefficient in natural working condition is 1.318, and the slope is in stable status. In rainfall working condition, with the increase of rainfall, the rainwater infiltration and loading function is enhanced, and the displacement high-value area expands gradually and extends to the slope toe. In 25 mm/d, 35 mm/d and 45 mm/d rainfall condition, the safety coefficient is 1.001, 0.932 and 0.912 respectively. The slope is quite unstable in earthquake working condition, and the upside displacement and accelerated speed of the mid-slope is the greatest, and it is easy-sliding area. In the coupling working condition of rainfall and earthquake, the upside of mid-slope is extremely unstable, and with the increase of rainfall, the displacement and accelerated speed would increase.