水位下降诱发含水层-弱透水层1维黏弹性固结分析  

One-dimensional Viscoelastic Consolidation Analysis of Aquifer-Aquitard Due to Drawdown of Water Level

作　　者：徐进[1] 杨伟涛 陈征 王少伟 XU Jin;YANG Weitao;CHEN Zheng;WANG Shaowei(School of Civil Eng.,Yantai Univ.,Yantai 264005,China;Key Lab.of Rock Mechanics in Hydraulic Structural Eng.(Wuhan Univ.),Ministry of Education,Wuhan 430072,China)

机构地区：[1]烟台大学土木工程学院,山东烟台264005 [2]武汉大学水工岩石力学教育部重点实验室,湖北武汉430072

出　　处：《工程科学与技术》2021年第5期89-97,共9页Advanced Engineering Sciences

基　　金：国家自然科学基金项目(41602284);烟台大学研究生科技创新基金项目(YDZD2006)。

摘　　要：过量开采地下水引起的地面沉降是一种严重的环境地质灾害,其具有土层变形长期发展的特点,弱透水层黏性土与含水层砂土的流变性是导致这一现象的重要原因之一。为此,采用广义开尔文模型描述弱透水层和含水层的流变性,结合太沙基1维固结理论和连续性条件,建立了水位变化诱发弱透水层–含水层双层系统流变固结的控制方程和定解条件。利用Laplace变换,给出基于传统矩阵传递法和边界转换法,分别推导了该双层系统在Laplace域内孔压和沉降的计算公式;采用Stehfest逆变换方法进行数值模拟并编写计算程序,得到真实物理空间解。通过与已有单层解析解、双层模型试验值和数值模拟结果的对比,验证了本文解法和程序的正确性。对比研究表明,相比于传统矩阵传递法,边界转换法可以将混合边界条件转换成单一边界条件,具有更高的计算精度和计算效率。最后,基于边界转换法,利用总沉降定义的固结度,研究了土体黏滞性系数、渗透系数以及水位下降速率等因素对土层长期变形的影响。结果表明:渗透系数和水位下降速率的影响主要体现在前中期,渗透性越小,水位下降速率越慢,固结发展得越慢;黏滞性系数的影响则主要体现在土层变形的后期,黏滞性越强,同等水位变化条件下变形完成所需时间越长。Land subsidence is mainly caused by excessive exploration of groundwater resource,which has been a common and serious geological hazard.Land subsidence has the characteristics of the long-term development of soil deformation,in which one of the main reasons for the phenomenon is the rheology of clay in aquitard and sand in aquifer.Therefore,based on the generalized Kelvin viscoelastic model used to simulate the rheological properties of aquitard and aquifer,combined with Terzaghi’s one-dimensional consolidation theory and continuity condition,the equation governing rheological consolidation and definite solution condition of long-term deformation of the aquitard–aquifer foundation owing to groundwater level variation are obtained.Using Laplace transform,based on traditional matrix transfer method and boundary transform technique,the calculation formulas of the pore water pressure and settlement of the two-layer system in Laplace space are derived,respectively.In order to obtain the solutions in time domain,the Stehfest method is used to calculate numerical inverse transformation and the computation program has been developed.Compared with the existing analytical solutions of single-layer soil,the experimental results and numerical simulation results of two-layer system,the two methods and computation program are verified.In contrast to the traditional matrix method,the boundary transformation technique can transform the involved mixed-type boundary conditions into more tractable uniform boundary conditions;in the meanwhile,it has higher computational accuracy and efficiency.Finally,based on the boundary transformation technique and average consolidation degree defined by the total settlement,more numerical examples have been conducted to investigate the influences of viscosity of skeleton,soil layer per-meability and water head falling rate on the long-term deformation of two-layer soil.The results show that the influences of permeability coeffi-cient and drawdown rate on consolidation progress are mainly ref

关 键 词：地下水位变化 地面沉降 双层地基 黏弹性模型 半解析解 

分 类 号：TU433[建筑科学—岩土工程]