Study on safety warning indicators for seepage in upstream clay impermeable earth-rock dams following severe drought conditions

Conventional seepage safety early warning approaches predominantly depend on monitoring data related to seepage safety. However, in arid environments characterized by the absence of water or significantly low water levels within reservoir areas, traditional seepage safety monitoring methods fail to yield reliable data, thereby impeding the implementation of effective early warning systems. This study proposes the utilization of parameter indicators associated with clay dry shrinkage cracks induced by severe drought as a basis for conducting seepage safety early warning assessments. The research involves analyzing the shrinkage stress of clay in arid conditions and examining the development of cracks in clay impermeable bodies. A method for calculating the depth and width of shrinkage cracks is proposed and validated through soil sample tests. By analyzing the distribution of soil matric suction during drought, a relationship between crack depth and width is established, allowing for the estimation of crack depth based on the width of shrinkage cracks. Using the Baiguishan Reservoir as a case study, calculations indicate that a crack width of 0.52cm is identified as a warning indicator for potential seepage damage in the clay impermeable body. The findings can aid in the operation and management of earth-rock dams during drought conditions.