Experiment Research On Regularity Of Moisture Migration In Embankment Filled By Red Clay

Red clay is a kind of high liquid limit soil widespreads in karst zone, which forms as a result of the weathering from limestone, and widely distributing in the southern region of our province. along the highway project ChenZhou–NingYuan Expressway, there is a great deal of red clay,because of the special engineering properties ,using the red clay without pretreatment for the subgrade filling caused a lot of engineering problems,such as high natural moisture content, poor water-stability, low compaction degree, embankment surface is vulnerable to cracking, etc. Changing the high liquid limit red clay for better soil need more place to deposit the waste and provide better soil,that will occupy land resources and influense our nature enviroment. Therefore, we have to make full use of this high liquid limit red clay to subgrade filling,and study the mechanism of the disease caused by moisture changing so that to prevent the disease by proper measures.Red clay has a very significant cracking characteristics, so embankment surface is vulnerable to cracking, crack is good channel for water invasion and water evaporation, which speed up the moisture it moves and Lead to the circulation of moisture content changed with climate, consequently, it influences the physical nature of the red clay and makes the hidden trouble of the disease. So the research for the mechanism of water-disease of subgrade filling by red clay will play a vital role to avoid the disease. This article made a investigation for the cracking situation of the embankment surface in the red clay area, and made the representative jobs in the typical location during the excavation construction, such as selecting location , insitu tests, collecting earth,the establishment of cracking model of red clay;we carryed out some tests for the red clay in room:physical and mechnical properties tests,cracking test, permeability test,moisture migration regularity test; againsting the existing problem of insufficient apparatus and means, some new apparatus and devices were developed for determing the water permeability of the soil under different situations,such as:field water permeability measurement apparatus with precise control(water permeability measures in situ),water permeability measurement apparatus with compressive stress(water permeability measures in room for saturated sand ), water permeability measurement apparatus with varying head and compressive stress(water permeability measures in room for saturated clay ), moisture migration measurement devices for unsaturated soil.Finally,use Geo-Studio series software to set up model of a typical cross-section of the filled embankment in highway project of ChenZhou–NingYuan Expressway ,the numerical simulation of the moisture migration regularity under the condition of rainfall in embankment filled by red clay is carried out ,thus to provide useful reference for the treatment technology of the embankment disease.