Study On The Karst Development Characteristics Of Zhulin Test Section Yun-Gui Railway And Its Influence On The Project

Carbonate rocks distribute Widely in China, especially in regions of southwest including Yunnan、Guizho、Guangxi and so on areas, Karst development situation is very serious, it has brought great harm to the construction and operation of railway and highway and other linear engineering. Aiming at the Karst Subgrade to put forward effective engineering measures is very meaningful.The new railway line of Yun-Gui in Yunnan province lengh is about 434km, Carbonate rocks are widely distributed along the railway line. In Zhulin test section various karst morphologies are developed, harmful effect of surface and underground karst on railway construction significantly. Therefore this paper selects Zhulin test section of the new railway line of Yun-Gui as the object of study. Based on the field investigation to research the karst development characteristics and its influence on engineering.The purpose of this paper is as follows:Through field investigation, field test and drilling data to identify the characteristics of the test section in karst development, and put forward rectification measures, to do numerical simulation aiming at the process and the form of groundwater dissipation before and after the grouting remediation.The main contents of this paper and the results are as follows:(1) Having a profound understanding about the geological conditions of the test section and the study area. Zhulin test section Yun-Gui railway located eastern Yunnan karst plateau landscape area, carbonate bedrock is almost here, and dissolution is strong, structure relative growth.(2) After the statistical of the drilling data of the test section and the completion of the field test, to analyse and summarize the ups and downs of the bedrock surface and Surface erosion crush belt, the development of underground cave, the change of the thickness of covering, the changes of groundwater level of the four short sections, to get the karst development law of test section.(3) There are 43.7% karst line sections in the new railway line of Yun-Gui all fronts. To summarize the distribution characteristics、the combination form and karst development degree of karst along the test section, we discover depression uvala is the most widely distributed, the highest hazard karst developmental type. Peak cluster depression and karst hills and depressionst as the most common erosion landform, accounted for 44%,26% of the karst line sections. Therefore, we make the development of peak cluster depressions and karst hills and depressions as the research focus.(4) Zhulin test section mainly distributed in the middle part of watershed area between Jiumo River and Nanqiu River. Karst depression uvala evolved bidirectionally. Affected by the headward erosion of regional rivers one side, and continued the characteristics of its evolution on the lysogenic surface. It possesses the characteristics of the supply type depression uvala:its flat shape is dish mainly; the underground krast space is not large but relatively uniform; the soil thickness is large, the structure is diversified; and the groundwater depth is shallow, the dynamic change is faint.(5) This paper uses the numerical simulation method, to simulate the dissipation of groundwater changes with time for different forms of karst development, to evaluate the safety of subgrade in the rainfall condition for different forms of karst development and then.(6) Finally, according to the site conditions of the Zhulin test section, we put forward the highly targeted treatment measures, and evaluate the grouting effect.