摘要
处于高水头条件下,水化学溶液的存在是诱发水泥砂浆结构失稳破坏的重要影响因素。针对这一问题,以水泥砂浆为试验研究对象,利用三场耦合试验测试系统和多功能材料伺服试验机对不同水化学溶液长期浸泡后的水泥砂浆试样进行基本材料力学试验和水力劈裂试验,对比分析不同水化学溶液下水泥砂浆水力劈裂形态、抗拉强度和水力劈裂临界水压力的演化规律。结果表明:不同的水化学溶液对水泥砂浆宏观性能的影响是不同的,水泥砂浆的劣化程度与溶液中离子成分和pH值密切相关,pH=3硫酸钠溶液中的水泥砂浆侵蚀后期损伤劣化程度逐渐加剧,大于pH=7,但仍小于pH=1硫酸钠溶液水化学溶液作用下水泥砂浆试件均呈现弱化的趋势,其水力劈裂临界水压力和材料强度的损伤劣化程度显著,但水泥砂浆水力劈裂临界水压力和抗拉强度损伤劣化程度存在明显差异,其中水力劈裂临界水压力劣化程度大于抗拉强度。同时,化学侵蚀下水泥砂浆水力劈裂临界水压力与抗拉强度之间的相关关系比较明显。从化学侵蚀后含初始裂缝的水泥砂浆断裂应力的降低和裂缝的增大这两个主要影响因素出发,分别引入缝长损伤系数和材料强度损伤系数,建立了化学侵蚀下水泥砂浆水力劈裂破坏准则,并提出了水力劈裂临界水压力与抗拉强度间的函数模型,结合大量的试验数据进行了验证,最后给出了两者存在函数关系的适用条件。
The chemical erosion has a significant influence on the induction of the instability of cement mortar structure under high water pressure conditions. In this study, the cement mortar is tested on the three-field coupling test system and servo-controlled testing system. The hydraulic fracturing morphology, the evolution regularities in tensile strength and critical water pressure of hydraulic fracturing are analyzed by long-term chemical corrosion. The research results indicate that the effects of four solutions on the macro-performance of cement mortars are different. At the later stage of immersion stage, the damage deterioration of the cement mortar specimens soaked in pH=3 Na2SO4 solution increases with the immersion time. The degree of damage deterioration in pH=1 Na2SO4 solution is the greatest, followed by those in pH=3 Na2SO4 solution, and then in pH=7 Na2SO4 solution. There are significant differences between tensile strength and the critical water pressure of hydraulic fracturing for corrosion degree under the action of water chemical solutions. As to the same condition, the corrosion degree of critical water pressure of hydraulic fracturing is greater than the tensile strength. Meanwhile, there is an obvious correlation among the critical water pressure of hydraulic fracturing and tensile strength of cement mortar under different chemical solution circumstances. In addition, the damage variable of fracture length and material strength are defined in terms of the failure criteria on critical stress of hydraulic fracturing which can be presented. Moreover, the functional correlation between the critical water pressure of hydraulic fracturing and tensile strength is presented, and a great quantities of experimental data are used to prove the analysis results. Finally, the applicable condition of functional relationship between critical water pressure of hydraulic fracturing and tensile strength is given.
作者
刘得潭
沈振中
徐力群
吴琼
汪瑞欣
LIU Detan;SHEN Zhenzhong;XU Liqun;WU Qiong;WANG Ruixin(Datang Hydropower Science&Technology Research Institute,Nanning 530007,China;College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China;Institute of Computer and Information Technology,Hohai University,Nanjing 210098,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2020年第S01期263-271,共9页
Journal of China Coal Society
基金
国家自然科学基金资助项目(U1765205)
长江科学院开放研究基金资助项目(CKWV2017515/KY)
关键词
水泥砂浆
化学溶液
水力劈裂
破坏准则
相关性
cement mortar
chemical dissolution
hydraulic fracture
failure criterion
correlation
