高混凝土坝考虑水表面张力影响的水力劈裂研究

水力劈裂是200m以上高混凝土坝、高碾压混凝土坝需要重点关注的安全隐患。为深入研究高混凝土坝的水力劈裂机理,研发了一种新型混凝土高压水劈裂试件,利用该试件进行了相同条件下水力劈裂及气压劈裂对比试验。研究表明,在静态加压条件下,混凝土发生破坏的水力劈裂水压显著大于气压劈裂的气压,混凝土断裂过程区中水的表面张力对裂缝扩展有抵抗作用。基于试验,提出了水表面张力抵抗劈裂作用的表达式,利用混凝土断裂力学中的裂纹尖端应力强度因子法,构建了考虑水表面张力作用的混凝土水力劈裂模型,该模型计算结果与试验结果吻合良好。应用水表面张力模型分析200m级重力坝水力劈裂影响,可进一步改进考虑高压水劈裂的特高混凝土坝设计。

Study on hydraulic fracturing of high concrete dam considering surface tension of water

Hydraulic fracturing is a potential safety hazard for high concrete dams and high RCC dams over 200 meters.In order to study the hydraulic fracturing mechanism of high concrete dam,a new type of concrete high pressure water splitting specimen was developed,and the hydraulic fracturing and pneumatic fracturing tests under the same conditions were studied by using the invented specimen.The results show that the water pressure of hydraulic fracturing is higher than that of pneumatic fracturing under static pressure,and the surface tension of water in the process of concrete fracture has a resistance to crack propagation.Based on the test,the expression of water surface tension resistance to splitting effect is proposed,and the concrete hydraulic splitting model considering water surface tension is constructed by using the stress intensity factor method at the crack tip in concrete fracture mechanics.The model calculation results are in good agreement with the experimental results.The water surface tension model is used to analyze the hydraulic fracturing effect of 200 meters gravity dams,which can further improve the design of super high concrete dams considering high-pressure water fracturing.