Statistical Analysis Of Face Slab Cracks And Numerical Simulation Study On Seepage Of Concrete Face Rockfill Dam

Concrete face rockfill dams(CFRDs)are widely used in hydropower engineering because of their low cost,small size,good adaptation to geological conditions,convenient construction,and good dam stability.The concrete face slab and the impervious curtain are important anti-seepage structures.When the anti-seepage system of a CFRD works normally,the seepage stability of the dam is guaranteed.There are many practical problems in the rapid development of the CFRD,mainly focus on a large number of cracks in the face slab caused by temperature-induced stress,shrinkage stress,deformation of dam,and the deterioration of the impervious curtain,which eventually lead to leakage of the dam body and dam foundation,threatening the safety of the dam.Therefore,it is significant to study the face slab cracks and the seepage characteristics under many abnormal conditions to ensure the stability and safety of dams.In this paper,statistical analysis and numerical calculation are used to systematically study face slab cracks and seepage characteristics of a CFRD under abnormal conditions.The main research contents are as follows:(1)This paper counts the face slab cracks of CFRDs at home and abroad,analyzing the cracking causes,cracking stages and cracking locations of face slabs.When the anti-seepage structure of the dam is abnormal,it is necessary to take corresponding measures to conduct seepage control in time.(2)Combined with the statistical cases of the face slab cracks,the equivalent continuum method is proposed.The finite element analysis method is combined with the block equivalent continuum method to calculate the three-dimensional seepage field of the dam area,then the size of the block is determined by comparing the seepage discharge in the dam area.The small-dimension block equivalent continuum method is used to study the seepage field of CFRDs with numerous and unevenly distributed cracks.Then the corresponding head distribution and seepage characteristics,including the phreatic line,the hydraulic gradient and the seepage discharge,are obtained.By comparing and analyzing whole equivalent continuum method of the face slab an the small-dimension block equivalent continuum method of the face slab,the accuracy and reliability of the small-dimension block equivalent continuum method are verified.(3)Based on the equivalent continuum method,the seepage and influencing factors of the CFRD are analyzed.3D finite element numerical simulations of the seepage of the actual project are performed.The seepage field and seepage characteristics are analyzed and compared quantitatively and systematically under various abnormal conditions,including cracks in different areas of the face slab and different degrees of degradation in the impervious curtain.