The Research On Subgrade Basement Survey And Disease-Treating Technology In Typical Karst Areas Of Guangxi

In karst areas investigation and treatment of subgrade base is a major problem during Highway construction. This paper discusses two typical kinds karst problems existing in basement of highway in Guangxi. One is the exposed-karst disease at Sui-nan highway, the other is soil-covered cave disease of Gui-yang highway. After deeply investigating and analyzing about the domestic survey methods of karst collapse, new technologies and new methods of karst treatment construction, subgrade karst treatment technology and the investigation technology of basement the was carried out by the way of site surveys, typical cases, the combination of theoretical analysis and field test. Basing analysis of soil cave features in Guiyang highway, three geophysical methods including ground penetrating radar (GPR), shallow earthquakes and high-density resistivity were chosen as a comparative testing method of the on-site soil cave investigation. Excavation of the site was used to verify the accuracy of these methods. Then the conclusion of GPR be the best soil cave survey method in Guiyang highway was drawn out .According to the principle of attach much importance to karst water in soil cave treatment, two basic methods of treatment were carried out: Excavation-filling + geotextile filter, drilling and grouting method. Also defined the scope of application of the two methods. Through an analysis of the form features of exposed karst beside Sui-nan highway, the two major factors that affect the stability of karst roadbed were known well, they are the uneven pattern of karst features and the role of karst water. In accordance with problem of the karst water and feature, the disposal principles and measures were given respectively. The most important is that th different measures must adapt to different scale of karst forms. In this principle treatment of exposed karst problems and the delineation of the specific indicators were established. Finally, all kinds of treatment methods were summarized, also their successful applications to deal with the changeable karst water and complex karst are demonstrated by various engineering examples.