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W-OH砒砂岩固结体干湿循环特性及其细观机理
马雯波1,2, 丁哲1,2, 吴智仁3, 梁止水4, 杨才千1,4
1.湘潭大学 土木工程与力学学院, 湖南 湘潭 411105;2.湘潭大学 湖南岩土力学与工程安全重点实验室, 湖南 湘潭 411105;3.江苏大学 环境与安全工程学院, 江苏 镇江 212013;4.东南大学 土木工程学院, 江苏 南京, 210096
摘要:
[目的] 对W-OH砒砂岩固结体干湿循环特性及其细观机理进行研究,为实现W-OH固结改良砒砂岩及其耐久性研究提供科学依据。[方法] 采用W-OH(亲水性聚氨酯材料)对砒砂岩进行固结处理,基于无侧限抗压试验、三轴抗压试验,研究其在干湿循环条件下的力学性能,并结合SEM,EDS和称重法对其干湿循环后样品微观结构、元素和质量损失进行分析,以获得其破坏机理。[结果] W-OH砒砂岩固结体的无侧限抗压强度、弹性模量和黏聚力在1~3次干湿循环后升高;在3~9次干湿循环后,固结体的力学强度降低;9次之后,剩下高黏结力的W-OH胶结体包裹于砒砂岩颗粒表面,力学强度趋于稳定。内摩擦角在1~9次干湿循环后上下波动,9次干湿循环后趋于稳定。采用碳元素分析和质量损失分析相结合的方法对土样中W-OH流失特性进行评价,发现土样在1~9次干湿循环中W-OH胶结体逐渐降低,并在9次干湿循环后达到稳定,这与上述宏观力学变化的规律相似,验证了破坏机理,为判断其长期特性提供理论依据。[结论] 研究表明可将9次干湿循环后达到稳定的W-OH砒砂岩固结体的力学性质作为土体的长期力学特性。
关键词:  干湿循环  W-OH砒砂岩固结体  无侧限抗压强度  三轴抗压强度  微观结构分析
DOI:10.13961/j.cnki.stbctb.2018.06.004
分类号:
基金项目:国家重点研发计划项目“砒砂岩区生态安全保障技术”(2017YFC0504505);国家自然科学基金项目(11502226);湖南省重点研发项目(2017WK2032)
Mechanical Properties and Meso-mechanism of Pisha Sandstone with W-OH Solidified Under Drying-wetting Cycles
MA Wenbo1,2, DING Zhe1,2, WU Zhiren3, LIANG Zhishui4, YANG Caiqian1,4
1.College of Civil Engineering and Mechanics, Xiangtan University, Xiangtan, Hu'nan 411105, China;2.Hunan Key Laboratory of Geomechanics and Engineering Safety, Xiangtan University, Xiangtan, Hu'nan 411105, China;3.School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China;4.School of Civil Engineering, Southeast University, Nanjing, Jiangsu 210096, China
Abstract:
The effects of drying-wetting cycles on the mechanical properties and meso-mechanism of the hydrophilic polyurethane material(W-OH) solidified Pisha sandstone were conducted to provide scientific basis for the study of W-OH consolidation amending Pisha sandstone and its durability. W-OH was used to consolidate the Pisha sandstone in this study. Macroscopic mechanical properties of the W-OH solidified Pisha sandstone were tested by unconfined compression experiment and triaxial compression experiment. To obtain the meso-mechanism, SEM, EDS and weighing methods were used to analyze the microstructure, elements, and quality losses of the sample after drying-wetting cycles. The results showed that unconfined compressive strength, elastic modulus, and cohesion of the W-OH solidified Pisha sandstone increased after drying-wetting cycles of 1~3 times. During drying-wetting cycles of 3~9 times, the mechanical strength of the W-OH solidified Pisha sandstone decreased. the rest solidified W-OH with high cohesive forces remained on the surface of the Pisha sandstone particles and the mechanical strength tended to be stable after drying-wetting cycles 9 times. The internal friction angle varied with fluctuation from 1 to 9 time drying-wetting cycles and stabilized after 9 times. The W-OH loss in the solidified soil samples was evaluated by the carbon element analysis and mass loss analysis. The solidified W-OH gradually decreased during drying-wetting cycles of 1~9 times and became stable after 9 times, which proved meso-mechanism of macroscopic mechanical properties above-mentioned and provided theoretical basis for long-term characteristics of W-OH consolidated Pisha sandstone. The results of this study suggest that the mechanical properties of W-OH solidified Pisha sandstone after 9 drying-wetting cycles can be considered as the long-term mechanical properties of this material.
Key words:  drying-wetting cycles  W-OH solidified Pisha sandstone  unconfined compressive strength  triaxial compressive strength  microstructure