冻融循环条件下单裂隙岩体损伤破坏特征研究

Damage Characteristics of Rock Specimens with Single Flaw under the Action of Freeze-Thaw Cycles

摘要: 我国疆域辽阔，在西部高海拔地区，昼夜温度变化明显，冻融循环现象普遍存在，而冻融作用会严重影响到裂隙岩体的物理力学性质，大大增加岩土工程的建设难度，而目前正在进行建设的川藏铁路部分区段正处于高寒区。因此，研究冻融作用对于裂隙岩体强度与稳定性的影响，越来越具有实际的工程应用价值。但是，国内外相关研究大多集中在理论分析与室内试验方面，而基于数值模拟的计算分析仍鲜有报道。故本文依托FLAC3D有限差分软件，并基于应变软化本构模型，对历经不同冻融循环次数后的具有不同裂隙倾角的岩体进行了单轴抗压模拟试验，而后利用模拟试验过程中获得的数据信息，从应力-应变曲线、峰值应力、残余应力以及塑性区发展规律等多个角度对裂隙岩体在冻融荷载耦合作用下的损伤破坏特征进行了分析与总结。研究结果表明，冻融作用会明显降低裂隙岩体的强度，加速破坏进程，并且其影响力会随冻融循环次数的增加而愈加凸显。

Abstract: China has a vast territory. In the high altitude area of western China, the temperature changes obviously day and night, and the freeze-thaw cycle is ubiquitous. The freeze-thaw action will seriously affect the physico-mechanical properties of fractured rock mass and greatly increase the difficulty of geotechnical engineering construction. At present, a part of the Sichuan-Tibet railway under construction is just in the high and cold region, therefore, it is of more and more practical engineering application value to study the influence of freeze-thaw action on the strength and stability of fractured rock mass. However, most of the relevant previous studies focus on theoretical analysis and laboratory tests, while the computational analysis based on numerical simulation is still rarely reported. Owing to these reasons, this paper is based on FLAC3D (finite difference software and strain softening constitutionality model), and uniaxial compressive simulation tests have been carried out for rock masses with different fracture dips after different freeze-thaw cycles. Then the damage and failure characteristics of fractured rock mass under the action of freeze-thaw cycles and load coupling have been analyzed and summarized by the stress-strain curve, peak stress, residual stress and the development law of plastic zone by using the data obtained in the simulation test. The results show that the freeze-thaw effect can significantly reduce the strength of fractured rock mass and accelerate the failure process, and its influence will become more prominent with the increase of freeze-thaw cycles.