Study On Engineering Characteristics Of Loess In Middle Pleistocene

In order to study the engineering characteristics of the mid-Pleistocene loess,L5 loess in the south of Jinyang was selected as the research object and a systematic analysis was carried out.On the basis of testing the basic physical index of L5 loess of South Jingyang plateau,this paper is mainly focused on the following aspects:(1)Determination of L5 pore distribution curve by mercury porosimetry.(2)The filter paper method was used to determine the matrix suction of L5 during Undisturbed and disturbed,and the test results were fitted.(3)Standard consolidation test was used to determine e~logP curves of L5 undisturbed loess under different Water contents.Determination of K0 Coefficient by Consolidation Apparatus Method.(4)Determination of Shear Strength of Remolded and Undisturbed L5 Loess at Different Water Contents by Direct Shear Test and Triaxial CD Test.(5)The maximum pure cohesion and tensile strength of the Undisturbed L5 loess under different Water contents were measured by two-sided shear and tensile tests.(6)Determination of Saturation Permeability of Undisturbed L5 Loess Using Conventional Permeation Test and Triaxial Test.According to the pore distribution characteristics,whether the mercury injection or withdrawal curve,the pore volume of saturated freeze-dried sample is smaller than that of natural air-dried sample with natural water content,It shows that L5 loess with saturated state still has a certain collapsibility.The volume of shrinkage caused by it is greater than the volume of shrinkage caused by natural air drying under conditions of natural water content.The pore size distribution curve of L5 has two peaks,0.03 ?m and 2.5 ?m,respectively.The measured SWCC shows that the water content of 10% is about the limiting water content of water migration from liquid water to gaseous water migration,the water content of15% is the turning point from rapid decline to slow start,and water content of 20% is the corresponding value of the intake value.The results of SWCC measurements of L5 were fitted by van Genuchten and Fredlund & Xing SWCC equations,and the results shows that the van Genuchten equation and Fredlund & Xing fit better.