Study On The Method Of Compaction And Grouting Used In The Karst Area Under The Lou-Xin High Way

ABSTRACT:With the development of highway construction, it is inevitable to go through karst areas, and Improving the reliability of the foundation in karst area has become a new topic of ground treatment. In this paper, the distribution of karst collapse area was clarified from the perspective of time and space, and the ground treatment methods in karst collapse area were studied by various types of soil tests. The main work is as follows:1、The stability of foundation in karst area of Lou-Xin Highway was evaluated by Semi-quantitative methods and the finite element theory. And the foundation treatment program in karst area of Lou-Xin Highway was proposed, with the consideration of the effect of roadbed construction and vehicle load, the size and depth of the cave on the roadbed.2、The method of compaction used in highway karst areas was studied by various types of soil tests. The tests resulted that, the horizontal and vertical deformation law of foundation was obtained under the effect of dynamic compaction, and the optimum tamping energy was obtained, and the effect depth of dynamic compaction treatment was presented, and the dynamic compaction program and the designed parameters were verified.3、Based on gelation test, strength test and contrast test of grouting material, the conclusion, which adding calcium carbonate can not only change the PH value of acid sodium silicate and but also the gelation time, is obtained. The result provides the experimental basis for the quality control of grouting treatment of karst foundation.4、The grouting control theory of the karst areas is discussed, and the control standards of the grouting volume and pressure are studied. The filling rate of the embankment construction is controlled correctly, the unloading time and the pavement constructing time is determined reasonably, and the earthwork calculation basis during construction is provided. They provide a reference for the engineering practice.5、The quality control technology of karst foundation engineering is studied. The treatment effect of karst foundation is verified through the comparative analysis of the geophysical results before and after treatment and the roadbed settlement observation after treatment.