Experimental And Simulation Study On Hydraulic Fracturing Of High Concrete Gravity Dam

For high concrete gravity dams,the cracks are often located at the bottom of the dam,that is the heel part.These cracks are often subjected to high water pressure.If the crack length is long enough,these cracks may cause leakage.If it is serious,it will affect the normal operation of the dam,and will have an adverse impact on the people’s economic and property safety and even the safety of life.Therefore,considering that the high concrete gravity dam works under the influence of constant high head pressure all year round,the cracks at the heel position of the upstream dam face of the high concrete gravity dam are studied to provide advice for dam construction,evaluate and evaluate the safety of the dam.It is of great significance to strengthen the operation and management of dams.This paper intends to conduct a hydraulic fracturing analysis of the cracks at the heel of a high concrete gravity dam through a combination of experimental research and extended finite element simulation research.The main research contents are as follows:(1)Using the method of built-in coin-shaped cracks to simulate dam cracks.Considering the problem of the pouring level of the roller compacted concrete construction,the interval of pouring the level is set to 5 hours,and there are two ways to deal with the level and not to treat it.The results show that the strength of concrete has a significant impact on hydraulic fracturing.If the construction level is not set,whether the construction level is set,and whether the construction level is processed,the strength and hydraulic fracturing strength of the concrete will be affected to varying degrees.However,there is a time interval in this article.Under the premise of5 hours,this effect is negligible.(2)As far as hydraulic fracturing of concrete dams is concerned,the most important factor affecting the strength of hydraulic fracturing of concrete is the strength of the concrete itself.When the strength of concrete is higher,compared with low-strength concrete,the splitting water pressure will naturally be greater,and the ability of concrete to resist hydraulic splitting will increase with the increase in strength.When the compressive strength of concrete is 17.3MPa,the splitting water pressure is 1.7MPa;when the compressive strength of concrete is 24.5MPa,the splitting water pressure is 2.5MPa;when the compressive strength of concrete is33.1MPa,the splitting water pressure is 3.4MPa(3)Based on the bond crack unit model established by ABAQUS,combined with concrete damage,concrete constitutive relationship and concrete seepage-stress coupling model,a concrete hydraulic fracturing analysis model with seepage function is established.In the modeling and analysis of the concrete hydraulic fracturing specimens,it can be found that when the crack width changes suddenly,the normal stress of the crack in the Z direction at this time,namely S33=3.4MPa,and the split hydraulic pressure obtained from the test unanimous.(4)The established concrete hydraulic fracturing analysis model is applied to a solid high concrete gravity dam,and it is verified that there will be no hydraulic fracturing in the dam.After manually setting up two cracks with different lengths,considering the most unfavorable water pressure situation,the default is that the materials of the dam body and the dam foundation are the same.As the length of the crack increases,the crack gradually expands to the dam foundation,and the degree of expansion increases with the crack increase in length.