摘要
天津市地下工程施工主要集中在粉土层处,这类土层极易随地下水的流失而流失,在该类地区的地下结构在施工及运营期间也易出现渗漏现象.其中土体的工程性质与渗透特性是这种渗流侵蚀灾害的重要影响因素.因此很有必要对天津粉土的工程性质,尤其是渗透特性进行标定.为确定天津地下承压含水层中粉土的渗透特性,首先开展室内试验研究,适当地加工改造《土工试验方法标准》中规定的标准试验仪器,通过比重试验、颗粒分析试验、液塑限试验对天津粉土进行比重、级配、液塑限等基本参数进行标定,详细汇总整理各个试验数据,应用相关公式及数据处理方法对大量试验数据展开分析得出试验结果;然后通过常水头渗透试验与变水头渗透试验相结合的方式对粉土渗透系数的变化特征进行分析.研究结果表明:天津粉土的渗透系数随孔隙率的增大呈现增大的趋势,随时间的增长而减小且最终趋于稳定.从天津粉土的土体特性出发,将既无法传递净水压,也不能产生渗流的由结合水占领的无效孔隙排除,剩下的孔隙比定义为有效孔隙比.利用有效孔隙比的概念对经典的太沙基渗流理论进行修正,提出了适用于天津粉土的渗透系数估算公式.该公式能很好地计算天津粉土的渗透系数,可为天津市承压含水层中地下施工的灾害防治工作提供参考.
The underground engineering construction in Tianjin is mainly concentrated in the silt soil layer,which is easily lost with the loss of groundwater.In addition,the underground structure in this area is prone to leakage during construction and operation.The engineering properties and seepage characteristics of soil are important factors affecting the seepage erosion hazard.Thus,it is necessary to calibrate the engineering properties of Tianjin silt,especially the permeability.To determine the permeability characteristics of silt in the underground confined aquifer of Tianjin,first,laboratory tests were carried out to properly process and transform the standard test instruments specified in the“Standard for Soil Test Method”.Basic parameters such as specific gravity,grade,and liquid plastic limit of Tianjin silt were calibrated through specific gravity test,particle analysis experiment,and liquid plastic limit test.Each test data was then summarized and sorted in detail.A large number of test data were analyzed using relevant formulas and data processing methods to obtain the test results.The variation characteristics of the silt permeability coefficient were then analyzed by the combination of constant head permeability test and variable head permeability test.Results show that the permeability coefficient of Tianjin silt increases with the increase of porosity,decreases with the increase of time,and finally tends to be stable.Based on the characteristics of Tianjin silt soil,the invalid pores that are occupied by bound water that cannot transfer water purification pressure and cannot produce seepage are excluded,and the remaining pore ratio is defined as the effective pore ratio.This paper uses the concept of effective pore ratio to modify the classical percolation theory of the Terzaghi foundation and proposes an applicable formula for estimating the permeability coefficient of Tianjin silt.The formula more precisely calculates the permeability coefficient of Tianjin silt.Results of this work could provide a
作者
郑刚
王佳琳
佟婧博
张天奇
Zheng Gang;Wang Jialin;Tong Jingbo;Zhang Tianqi(School of Civil Engineering,Tianjin University,Tianjin 300072,China;Key Laboratory of Coast Civil Structure Safety(Tianjin University),Ministry of Education,Tianjin 300072,China)
出处
《天津大学学报（自然科学与工程技术版）》
EI
CAS
CSCD
北大核心
2022年第1期77-84,共8页
Journal of Tianjin University：Science and Technology
基金
国家自然科学基金重点资助项目(41630641)
国家自然科学基金青年基金资助项目(51808387).
关键词
天津粉土
颗粒级配
比重
液塑限
渗透试验
太沙基
Tianjin silt
particle gradation
specific gravity
liquid plastic limit
penetration test
Terzaghi
