Study on Shrinkage Characteristics and the Law of Crack Propagation of Compacted Red Clay

Abstract

Key word:compaction;red clay;shrinkage deformation;crack Characteristics Abstract:The red clay has high moisture content, high plasticity, high void ratio and other special engineering properties,especially when the subgrade surface dehydrates,it shrinks and cracks,caused the subgrade to have some diseases.Taking the subgrade filling from Liupanshui inner Expressway as the research object,doing the shringkage test to the red clay,measuring the shrinkage deformation and the crack characteristics of the red clay during the shrinkage process,got the law of the shrinkage deformation and evolution of the crack of the red clay under shrinkage condition. Foreword Because the red clay has high moisture content, high plasticity, high void ratio and other special engineering properties,with the operation time of the highway growing,the subgrade and pavement has some diseases.The Guiyang-Zunyi Expressway,the Guiyang-Bijie Expressway and some other expressways have a lot of ruts. In the survey we also found that a large number of pavement cracks, the crack size is different and the crack shape is irregular, the most serious crack is the vertical crack casued by sink,the length of the crack is more than a hundred meters, the pavement also has large area subsidence,these all mainly casued by subgrsde subsidence. There also has some problems of different degrees of red clay in other roads has been built outside Guizhou province.Such as 107 National Highway in Moyang,the semi-rigid type base,the surface course and the cement pavement always appear crack, slab pumping and crack slab.During the construction of the Beijing Zhuhai Expressway between Moyang and Yizhang,using a lot of red clay to filling embankment near Yizhang,making the embankment surface appear serious shape crack and fissuring,he crack size is different,The maximum width is up to5-6cm, depth is up to 26cm.The fundamental reason of subgrade pavement cracking is the red clay shrink because of the r educe of water. So the research of the deformation of red clay has a practical significance on highway construction in red clay area.