Reliability analysis of service life for ultra-high core-wall rockfill dam considering the seepage-dissolution effect of dam foundation impervious structure
Ultra-high core-wall rockfill dams exhibit highly non-homogeneous cement-based impermeability,which significantly affects the accurate assessment of the long-term performance of the dam foundation's impervi-ous structure under the seepage-dissolution effect.Based on the Karhunen-Loeve expansion method,the random field of cement-based material parameters is discretized.A multi-layer forward neural network model was estab-lished as the core to map the relationship between random fields and service life.A service life reliability analysis method was thereby developed.Taking the Changhe dam project as the background,the seepage and dissolution characteristics of cement-based materials under random permeability coefficient,porosity,and solid phase calci-um concentration were studied.The accuracy of the neural network prediction model was verified,and service life reliability analysis of the ultra-high core-wall rockfill dams was carried out.Permeability erosion would enhance the spatial variability of the permeability coefficient of the cement base impermeability.The unit seepage discharge of the dam body and foundation under the random condition of cement-based material parameters is 0.87-1.19 times that under the average condition.The service life of the dam foundation with 95％guarantee rate is 63.4 years.From impermeability and mechanical perspectives,reducing the average permeability coefficient of the main anti-seepage curtain,average permeability coefficient and spatial variability of consolidation grouting can more effectively prolong the service life of the dam.The non-homogeneity of the cement-based impervious struc-ture of the dam foundation should be emphasized in the design,construction,operation,and maintenance of ul-tra-high core-wall rockfill dams,considering the seepage-dissolution effect.
万方数据
维普
