考虑Hansbo渗流及变井阻的竖井地基非线性大应变固结分析  

A NUMERICAL SOLUTION FOR NONLINEAR LARGE-STRAIN CONSOLIDATION OF VERTICAL DRAIN-IMPROVED SOILS BY CONSIDERING HANSBO’S FLOW AND TIME-AND-DEPTH DEPENDENT WELL RESISTANCE

作　　者：李阔 李传勋[1] 郭霄 LI Kuo;LI Chuan-xun;GUO Xiao(Faculty of Civil Engineering and Mechanics,Jiangsu University,Zhenjiang,Jiangsu 212013,China;Zhejiang Highway and Waterage Engineering Consulting Co.Ltd.,Hangzhou,Zhejiang 310006,China)

机构地区：[1]江苏大学土木工程与力学学院,江苏镇江212013 [2]浙江公路水运工程咨询有限责任公司,浙江杭州310006

出　　处：《工程力学》2024年第9期144-154,共11页Engineering Mechanics

基　　金：国家自然科学基金项目(51878320)。

摘　　要：大量资料表明,软土中孔隙水渗流在低水力坡降时会偏离达西定律,同时高压缩性软土在外载作用下产生的较大应变致使经典的小应变固结理论不再适用,竖井地基中的软土大应变也必然导致排水体发生弯折、出现淤堵等不良排水状态从而影响竖井的通水量。基于此,应用经典的Hansbo渗流定律描述软土中的渗流规律,采用随时间、深度变化的变井阻模型描述竖井在固结过程中通水量的变化,在Gibson大应变几何假定下建立可以考虑外荷载随时间变化的竖井地基大应变非线性固结模型,并给出其数值解答。通过与退化工况下已有的解答和工程实例开展对比分析,验证所建固结模型的可信性。对不同工况下的竖井地基大变形固结性状进行分析时发现:Hansbo渗流参数m和i1在合理取值范围内时其与达西渗流竖井地基固结度间的差异可高达10%,但当井径比小于13时,两者间的差异不到5%,此时可忽略土中存在的非达西渗流现象,一旦井径比超过13,竖井地基固结计算就有必要考虑土中的Hansbo渗流现象;变井阻导致竖井的通水量逐渐降低,在考虑土中Hansbo渗流后,变井阻与常井阻计算的竖井地基平均固结度间的差异最大达10%;竖井长度与竖井影响区半径之比(H/r_(e))达到12.5时,土中竖向渗流已影响甚微,且随着H/r_(e)的增大竖向渗流的影响会更小,此时可忽略不计。Numerous data show the deviation of the pore water flow from the Darcian law during low hydraulic gradient.Meanwhile,the classical small-strain consolidation theory becomes no longer applicable because of the large strain generated by soft soil with high compressibility under the external load.And the large strain will lead to the bending of the drainage body,the occurrence of silting,and other poor drainage conditions.Based on this,the Hansbo’s flow is used to describe the non-Darcian flow in soft soil,and the time-and-depth dependent well resistance model is used to describe the reduction of drainage capacity.The large-strain nonlinear consolidation model with vertical drain under time-dependent is presented,and its numerical solution is derived.The solution is compared with the existing solutions and an engineering case to verify its correctness.When analyzing the consolidation properties under different working conditions,it is found that the difference of consolidation degree between the Darcian flow and Hansbo’s flow can be as high as 10%only if the Hansbo’s flow parameters m and i1 are within a reasonable value range.However,the difference between the two is less than 5%when the radius ratio is less than 13.At this time,the non-Darcian flow in the soil can be ignored.Once the radius ratio exceeds 13,it is necessary to consider the Hansbo’s flow.Variable well resistance leads to a gradual decrease of drainage capacity in vertical drain,and the difference of the consolidation degrees calculated by the variable well resistance and by the constant well resistance is up to 10%after considering the Hansbo’s flow.When the ratio H/r_(e) reaches 12.5,the vertical flow in soil has little effect,which will be even smaller with the increase of H/r_(e) and can be approximately ignored at this time.

关 键 词：岩土工程 竖井地基 数值解 Hansbo渗流 变井阻 大应变 非线性固结 

分 类 号：TU447[建筑科学—岩土工程]