摘要
成层土中基坑渗流场与均质土层中渗流场有较大差别,最有可能发生突涌事故的位置也不同,因此准确确定成层土中基坑二维稳态渗流场是基础工程建设中的重要课题。针对成层土中基坑稳态渗流问题,将基坑周围土体按成层条件划分为多个区域,采用叠加原理和分离变量法给出各区域水头分布的级数形式解,根据各区域间连续条件和傅里叶级数正交性求得成层土中基坑二维稳态渗流场水头分布的显式解析解。将解析解计算得到的水头分布、挡墙水压力与有限元软件计算结果进行验证,并将解析解退化为单层土形式与半解析解进行对比,结果吻合较好,验证了解析解的正确性和有效性。将解析解与考虑水土相互作用的水压计算方法和等效渗透系数方法进行对比,基于解析解进一步给出计算基坑内出逸比降、挡墙水压力和抗突涌安全系数的计算公式,并结合工程案例分别采用解析方法和等效渗透系数方法对成层土中基坑的抗突涌性能进行分析对比。研究结果表明:解析解在求解成层土中基坑渗流场时更贴合实际情况;考虑不同土层间渗透系数差异时,水头在渗透性较差的土层中变化更快;上层土体渗透系数较小时,在土层分界面处发生突涌的风险比挡墙底部更大;等效渗透系数方法在求解某些成层土基坑渗流场时误差较大。
The seepage field in a layered soil excavation is significantly different from that in a homogeneous soil layer,and the most likely location for a sudden surge accident is also different.Therefore,accurately determining the two-dimensional steady-state seepage field in a layered soil excavation is an important issue in basic engineering construction.For the steady-state seepage problem in a layered soil excavation,the soil around the excavation was divided into multiple regions according to the layered conditions.The series solution of the water head distribution in each region was given by using the superposition principle and the separation of variables method.The explicit analytical solution of the water head distribution of the two-dimensional steady-state seepage field in the layered soil excavation was obtained according to the continuity conditions between the regions and the orthogonality of the Fourier series.The water head distribution and retaining wall water pressure calculated by the analytical solution were verified with the results of finite element software,and the analytical solution was degenerated into a single-layer soil form and compared with the semi-analytical solution.The results are in good agreement,verifying the correctness and effectiveness of the analytical solution.The analytical solution is compared with the water pressure calculation method considering the interaction between water and soil and the equivalent permeability coefficient method.Based on the analytical solution,the calculation formulas for the escape ratio drop,retaining wall water pressure and anti-surge safety factor in the excavation are further given.The anti-surge performance of the excavation in layered soil is analyzed and compared using the analytical method and the equivalent permeability coefficient method in combination with engineering cases.The research results show that the analytical solution is more in line with the actual situation when solving the seepage field in a layered soil excavation;when conside
作者
余俊
张志中
和振
李东凯
YU Jun;ZHANG Zhizhong;HE Zhen;LI Dongkai(School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2024年第1期194-203,共10页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(52078496)。
关键词
成层土
二维渗流场
解析解
正交性
抗突涌
stratified soil
two-dimensional seepage field
analytical solution
orthogonality
bursting
