干湿循环作用下玄武岩节理面剪切变形规律与改进的抗剪强度计算模型

Shear deformation patterns of basalt joint surfaces under dry-wet cycles and improved shear strength calculation model

摘要

【目的】大型水库的边坡消落带岩体常受干湿循环作用影响而产生劣化。为探究干湿循环作用下消落带玄武岩节理面剪切特性的劣化规律【方法】以白鹤滩水库边坡消落带玄武岩为研究对象，采用劈裂方式制备与天然节理面粗糙系数相近的节理面试样，开展了不同干湿循环作用下玄武岩节理面的直剪试验与三维形貌扫描测试，分析了节理面的剪切力学特性与细观形貌参数劣化规律，建立了考虑干湿循环的JRC-JCS模型。【结果】结果显示：随干湿循环次数的增加，抗剪强度呈现“先陡后缓”的劣化趋势，12次干湿循环过程中前5次的抗剪强度劣化幅度占总劣化的82.2%,且节理面的细观参数也相应降低；考虑干湿循环的JRC-JCS模型计算出的抗剪强度与室内试验值拟合效果较好。【结论】结果表明：节理面的细观形貌参数和粗糙度系数JRC与宏观抗剪强度的劣化规律一致，且形貌参数与抗剪强度具有良好的相关性；基于考虑干湿循环的JRC-JCS模型，能够利用节理面细观形貌参数变化，较为准确地预测节理岩体的抗剪强度劣化规律。

Abstract

[Objective] The rock mass within the slope hydro-fluctuation zone of large reservoirs often deteriorates due to dry-wet cycles. The aim is to investigate the deterioration patterns of the shear characteristics of basalt joint surfaces in the hydro-fluctuation zone under dry-wet cycles. [Methods] Basalt from the slope hydro-fluctuation zone of the Baihetan Reservoir was selected as the research object. Joint surface samples with roughness coefficients similar to those of natural joint surfaces were prepared using the splitting method. Direct shear tests and three-dimensional morphological scanning tests were performed on the basalt joint surfaces under different dry-wet cycles. The shear mechanical properties and the deterioration patterns of mesoscopic morphological parameters of the joint surfaces were analyzed, and a JRC-JCS model considering the dry-wet cycles was established. [Results] The result showed that with an increasing number of dry-wet cycles, the shear strength showed a deterioration trend of “rapid at first and then slowing down”. During the 12 dry-wet cycles, the deterioration in shear strength in the first five cycles accounted for 82.2% of the total deterioration, and the mesoscopic parameters of the joint surfaces also decreased accordingly. The shear strength calculated by the JRC-JCS model considering dry-wet cycles fitted well with the laboratory test values. [Conclusion] The findings reveal that the deterioration patterns of the mesoscopic morphological parameters and the roughness coefficient JRC of the joint surfaces are consistent with those of the macroscopic shear strength, indicating a good correlation between morphological parameters and shear strength. Based on the JRC-JCS model considering dry-wet cycles, the changes in mesoscopic morphological parameters of the joint surfaces can be used to predict the shear strength deterioration patterns of jointed rock masses.

关键词

水-岩作用 / 抗剪特性 / 形貌扫描 / 节理面粗糙度系数 / 干湿循环 / 力学特性 / 影响因素 / 劣化

Key words

water-rock interaction / shear characteristics / morphology scanning / joint surface roughness coefficient / dry-wet cycles / mechanical properties / influencing factors / deterioration

基金资助

国家自然科学基金区域创新发展联合基金重点项目(U22A20600)