Research On Dynamic And Static Analysis And Crack Expansion Of Rock-fill Dam With Cemented Gravel Soil Core

The core wall arch effect is an important factor that threatens the safety of superhigh core rockfill dam.Generally,gravel is added to the core wall to reduce the arch effect,but excessive gravel easily forms seepage passage,which is harmful to dam seepage prevention.The cemented gravelly soil with curing agent is better than gravel soil in anti-seepage performance,strength durability et al.Therefore,many experts considered adding HAS curing agent to gravel soil to make cemented gravelly soil core wall.The addition of curing agent can improve the deformation modulus of core wall and weaken the arch effect of core wall of super-high core rockfill dam.In this paper,the behaviors of cemented gravel soil core rockfill dam with different curing agent contents during service period were studied,including static and dynamic characteristics and core crack propagation.On this basis,the shape of cemented gravel soil core wall was optimized.The main research contents and results are as follows:(1)The static characteristics of cemented gravel soil core rockfill dam based on finite element method was studied with different curing agent contents during the completion period and the storage period.It is found that with the increase of curing agent content,the deformation modulus of cemented gravel soil gradually increases,the arch effect of core wall is improved during the completion period and the storage period,and the hydraulic splitting resistance of core wall is enhanced.The maximal vertical and horizontal displacements of the dam during the storage period decrease with the increase of curing agent content.The addition of curing agent improves the deformation coordination and the stress level of gravel soil core dam during the storage period.(2)The finite element model of seepage and slope stability of rockfill dam with cemented gravel core wall was established,and stability of dam slope and seepage during the storage period were analyzed with different contents of curing agent.The results show that the addition of curing agent can enhance the anti-seepage performance and slope stability.(3)Through the soil splitting test,it is found that the tensile strength and fracture energy of cemented gravel soil are significantly improved compared with gravel soil.On this basis,the research on crack propagation of cemented gravel core wall based on extended finite element method(XFEM)was carried out,and the influence of curing agent content on crack propagation performance was analyzed.It is found that the crack propagation resistance of core wall is improved with the increase of curing agent content.(4)Finite element analysis on dynamic characteristics of cemented gravel soil core rockfill dam with different contents of curing agent was carried out under the designed seismic magnitude,including acceleration and deformation of dam body,arch effect of core wall and stability of dam slope.The results show that the seismic performance of cemented gravel soil core dam is improved with the increase of curing agent content.(5)The body shape of cemented gravel soil core wall was optimized from two aspects: reducing top width and increasing slope gradient.It is found that the core wall arch effect is directly proportional to the top width and its slope gradient.The antiseepage performance,slope stability and seismic performance of rockfill dam are directly proportional to the top width and inversely proportional to the slope gradient of core wall.On the premise that dam safety during its service period is not affected,the shape with a slope gradient of 5 and a top width of 7m for the cemented gravel core wall is most optimum regarding to the curing agent mixture proportion of 6%,which leads to reduce construction quantity and save project cost.