Causal Analysis on the Deformation of Tailings Stacking Dam in the Tongtianping Gold Deposit in Hui County, Gansu Province

For the tailings stacking dam of the Tongtianping gold deposit in Hui County of Gansu Province, the foundation soil is silty clay with very low strength, its characteristic value of bearing capacity is 80~100kPa. When the initial dam is lower than 20.0m, it is piled up by silty clay, and then the later fill dam is built on the basis of the initial dam. During the production, the filter dry backfilling materials are used piled up by using the up-stream type tailing damming method. The groundwater of tailings stacking yard is rich. If the buried depth of groundwater level is nearby the earth's surface, the groundwater will expose as the boundary spring. Both the dam foundation soil and the dam body are the cohesive soils with strong water-holding capacity and poor permeability, both of them have a slope of about 10 °, and the dam foundation soil is distributed as a slope with angle of 5°~10°. Due to the weak foundation soil has not been processed, the drainage measures of dam foundation and dam body are very poor, leading to the uplift, cracking and collapse deformation damage for the dam (that was operated shortly before) body and dam surface, seriously affecting the normal use of the dam body. Through carrying out the later supplementary investigation, the remedial measures, such as foundation reinforcement and dam drainage, had been putted forward. After nearly two years of monitoring, it's proved that the dam body is steady and its operation is fine.