Analysis Of Static And Dynamic Stability Of Cracks In Concrete Gravity Dam

Reservoir dams are important engineering facilities for flood control and irrigation in various countries.Concrete gravity dams have always been relatively large dam types in dam construction.Cracks are inevitable in concrete structure during operation.The safety of gravity dam with cracks is directly related to the life and property interests of the downstream people.Therefore,it is particularly important to study the impact of cracks on the stability of gravity dams under static or seismic loads.This paper uses ANSYS finite element static and dynamic analysis method to analyze the static bearing capacity and seismic response of the concrete gravity dam with horizontal cracks.The main numerical simulation work and research results are as follows:(1)Select the RCC gravity dam with initial cracks,use the parametric design language(apdl)of ANSYS finite element software to establish a two-dimensional model of the gravity dam,and adopt the mixed mode I-II crack propagation criterion of concrete with the initiation toughness as the parameter,The loads considered in the calculation include: the hydrostatic pressure on the upstream,the hydrostatic pressure in the crack and the dead weight of the dam body,and the cohesive force of the fracture process zone(FPZ).Analyze the influence of the upstream initial horizontal crack height and crack length on the static bearing capacity of gravity dam under different load combinations.The reservoir water level-crack mouth opening displacement(H-CMOD)curve,reservoir water level-crackmouth shear displacement(H-CMSD)curve,fracture propagation path,and maximum fracture process zone length were obtained.The results show that the calculated cracking water level of 30 working conditions all exceed the dam height;When the loading conditions and the initial crack height of the gravity dam are unchanged,with the increase of the initial crack length,the crack mouth opening displacement(CMOD)in the initiating state,the crack mouth opening displacement(CMOD)and the crack mouth shear displacement(CMSD)in the limit state are increasing,the crack mouth shear displacement(CMSD)Before the limit state of the dam is basically unchanged,and the water level of the cracking reservoir,the limit reservoir water level and the maximum length of the FPZ of the dam are decreasing;When the loading conditions and initial crack length of the gravity dam are unchanged,the higher the crack,the lower theultimate bearing capacity of the dam;The existence of water pressure will significantly change the bearing capacity of the concrete gravity dam,which cannot be ignored in crack static stability analysis of gravity dam.The maximum fracture process zone considering the hydrostatic pressure in the crack is shorter;the crack extension paths of gravity dams are all towards the downstream surface or dam foundation Direction expansion.(2)An alternative RCC gravity dam with initial cracks is used for seismic response analysis.For the three working conditions of empty storage,the loads considered in the calculation include:dead water level and normal water storage level,consider the upstream hydrostatic pressure,hydrodynamic pressure,intra-fracture water pressure,dam weight,FPZ cohesion,seismic load,analysis of the effect of the height and length of the initial horizontal crack on the upstream surface on the bearing capacity of the gravity dam.The time history curve of the horizontal dynamic displacement of the crest of the dam crest,the time history curve of the vertical dynamic displacement of the crest,the time history curve of the crack mouth opening displacement(CMOD),the time history curve of the fracture mouth shear displacement(CMSD),the crack propagation path are obtained.The calculation results show that the earthquake has stronger destructive ability to the gravity dam.Under the action of the seismic load,cracks of a certain length will also expand in the empty reservoir;The load conditions and crack height are the same,the higher the water level,the greater the maximum displacement toward tthe direction of the water pressure upstream of the dam,but the maximum value of crack mouth opening displacement and crack mouth shear displacement becomes smaller;The crack propagation angle is gentle and expands towards the downstream surface.