Abstract:The karst of the limestone yard in Hangudi of Qiaojia County is poorly developed, but excavation reveals that there exists large karst pipelines. It will be significant to find out the law of karst development for the next mining layout of the material yard. In this paper, the distribution characteristics and location of underground karst and surface karst are analyzed through field investigation, drill hole and geophysical prospecting in and around the material yard, and combined with the study of geological characteristics such as structure, lithology, hydrology and geomorphology, the mechanism of karst development is analyzed and discussed, It is considered that the areas can develop karst anomaly zone in poor karst development ,under special hydrological condition.The results show that: (1) Due to the development of surface tributaries, the surface water can not be gathered, and the surface karst is not developed. (2) There is a fault spring at the trailing edge of the gentle slope platform above the material yard with a flow rate of about 1.8L/s, and the spring water seeps into the underground of the platform, which makes the underground karst caves of the material yard area are more developed than the surface; the Buddha Cave and the Bat Cave were preserved on the trailing edge of the Hangudi Platform, which was the exit of the karst caves at that time; (3) The underground karst passage first seeps into the underground in the fault spring of Pujia Village platform. The spring infiltrates into the ground and develops a “vertical” pipeline outside the steep slope of the cut-out slope along the Zhongliangzi groove, whose the diameter is about 12m. At the location of 1400m elevation, horizontal pipelines are developed along the bedding layer, and the karst water is discharged to the surface from Buddha Cave and Bat Cave on the right bank of the Dawanzi groove. With the uplift of the Hangudi platform, the karst pipelines are still discharged to the bottom of the Jinsha River by vertical pipelines, and the exit is in the Longtan area of Qiaojia County; (4) Due to the collapse of the pipeline and its vicinity, which filling of karst cave breccia and secondary mud, so the quality requirements of stone cannot be met, and the reserves of useful materials in the material yard area are reduced by about 10-15%.