Research On The Forming Environment Of Karst Soil Caves In The Representative Areas

Karst soil caves are unique geological disasters of the cover soil in Karst Area. In this paper, Qintang of Guigang, Baiyun of Guangzhou and Guiyang highway were chosen as typical sites. Through field investigation, data collection, Ground Penetrating Radar probe and other means, we could obtain karst soil caves’geological models and hydrodynamic condition of all the typical areas by analyzing the geological setting and the status of the karst soil caves.Based on these, through field monitoring and laboratory test, karst soil caves’formation environment was analyzed by groundwater factors, soil factors and the interaction between water and soil from the perspective of physics and chemistry.When analyzed groundwater factors of the study fields, two main points of view were considered: hydrodynamic condition and water chemistry. We could find out water environmental condition of the area by analyzing the ion composition and calculating the type of water chemistry, saturation index, PCO2,combined with groundwater monitoring. The results showed that the groundwater fluctuation and water chemical composition was closely related to karst soil caves’formation.Soil factors in the areas were mainly analyzed from the follow aspects:thickness of the overburden, soil structure, porosity, moisture content, saturation and other soil physical parameters, chemical and mineral compositions at different parts of the soil and so on. These results showed that karst soil caves were more proned to formation, as the soil layer was more thinner, cohesive soil was mingled with sandy gravel and bivariate or even multivariate structure of the soil. The soil structural strength was more higher next to surface and vary greatly downward due to the different structural components. When it came to the site of the bedrock surface, soil structure had low strength, less contents of soluble salt, and more probability to develop karst soil caves.The interaction between water and soil by the laboratory test showed that the collapse of the cohesive soil was closely related to the soil moisture content, mineral composition and so on. Especially in the wet and dry cycle conditions, the soil was prone to disintegration.Finally, this paper summarized the karst soil caves’ influence factors and distribution regularity of all the typical areas. It provided a new idea and useful exploration in order to explore the quantitative analysis of karst soil caves’formation on next step.