试样边壁及内部缺陷对土体渗透系数测量的影响分析

摘要

土体的渗透系数是评价土体渗透固结性能的重要指标.在心墙坝中,准确测定心墙料的渗透系数对评价心墙的固结变形和拱效应具有非常重要的意义.测量渗透系数的方法包括渗透试验和固结试验.由于试样边壁和内部缺陷的影响,这两种方法的测量结果均可能与实际土体的渗透系数存在一定偏差.本文通过对概念模型的理论分析和推导计算,研究了试样边壁和内部缺陷对渗透试验和固结试验测量渗透系数结果的影响.分析结果表明,试样边壁和内部缺陷均对渗透试验的结果有显著影响,而对固结试验的结果则影响较小.在选择渗透系数的测量方法时,应根据具体情况.在分析心墙坝的渗漏量时,宜通过渗透试验测定心墙料渗透系数,但需要对试样边壁进行处理,尽可能消除边壁效应的影响;在分析心墙的应力变形时,则宜通过固结试验测定心墙料的固结系数或渗透系数,以免高估了心墙的固结性能.%Permeability coefficient is an important index to evaluate the consolidation performance of soil.Accurate determination of the permeability coefficient of the core wall material is very important for evaluation for the deformation and the arch effect of earth core rockfill dam (ECRD).The methods of measuring permeability coefficient include seepage test and consolidation test.Because of the influence of boundary and internal defects of the sample,the measurement results of the two methods may have certain deviation from the actual permeability coefficient of soil.This paper studies the influence of boundary and internal defects of the specimen on the measurement of permeability coefficient by seepage test and consolidation test,based on theoretical analysis and numerical calculation of the conceptual model.The results show that both boundary and internal defects of the sample have significant influence on the results of the seepage test,while the result of the consolidation test is less affected.The choice of permeability measurement methods should be based on specific circumstances.When the leakage of ECRD is evaluated,it is better to measure the permeability coefficient of the core wall by seepage test,but the boundary of sample should be treated to eliminate the influence of boundary defects.When the deformation behavior of ECRD is evaluated,it is better to determine the consolidation coefficient or permeability coefficient through consolidation test,to avoid overestimation of permeability of the core wall.