傅鹤林,李欢,李鲒,等. 寒区炭质千枚岩冻−动联合损伤特性[J]. 煤炭学报,2024,49(S1):274−284. DOI: 10.13225/j.cnki.jccs.2023.0643
引用本文: 傅鹤林,李欢,李鲒,等. 寒区炭质千枚岩冻−动联合损伤特性[J]. 煤炭学报,2024,49(S1):274−284. DOI: 10.13225/j.cnki.jccs.2023.0643
FU Helin,LI Huan,LI Jie,et al. Freezing-dynamic combined damage characteristics of carbonaceous phyllite in cold region[J]. Journal of China Coal Society,2024,49(S1):274−284. DOI: 10.13225/j.cnki.jccs.2023.0643
Citation: FU Helin,LI Huan,LI Jie,et al. Freezing-dynamic combined damage characteristics of carbonaceous phyllite in cold region[J]. Journal of China Coal Society,2024,49(S1):274−284. DOI: 10.13225/j.cnki.jccs.2023.0643

寒区炭质千枚岩冻−动联合损伤特性

Freezing-dynamic combined damage characteristics of carbonaceous phyllite in cold region

  • 摘要: 由于寒区隧道围岩在冻融及动载的作用下会产生严重的损伤和性能退化,因此研究两者耦合作用下岩石的劣化特征具有重要意义。利用MTS815加载系统对炭质千枚岩试样开展了0、30、60次不同冻融循环次数下的三轴多级循环加卸载试验,研究了冻融及循环荷载对炭质千枚岩力学参数及变形的影响,基于能量计算分析了不同冻融次数岩石在动载下的能量演化规律,从宏观和微观角度进行对比,分析岩石在静载与冻−动耦合下的破坏形态,揭示了相应的破坏模式。试验研究表明:① 与静载压缩强度相比,在冻融和循环荷载共同作用下岩石的强度有明显的降低,并且表现出明显的塑性,同时冻融循环次数越多,该现象也越显著;② 随着冻融循环次数的增加,弹性模量会逐渐减小而泊松比却逐渐增大;③ 在循环过程中,轴向和环向不可逆应变均逐渐增加,两者的应变增量均在每一级应力的初始循环内最大而后逐渐减小,而不可逆体积应变先增大后减小,即体积先以压实为主后逐渐转变为以膨胀为主;④ 岩石内部主要以弹性能为主,耗散能占比在第1个循环周期内迅速降低,在之后的循环周期内呈现阶梯式增加而后趋于稳定;⑤ 从宏观与微观角度分析,单调加载与循环加载作用下两者的破坏机理不同,但均为斜截面的剪切破坏,但循环加卸载破碎程度更大。

     

    Abstract: The surrounding rock of tunnel in cold region would produce serious damage and performance degradation under the action of freeze-thaw and dynamic loads. Therefore, it is of great significance to study the deterioration characteristics of rock under the coupling effect of freeze-thaw and dynamic loads. In this paper, the MTS815 loading system was used to carry out the triaxial multi-stage cyclic loading and unloading tests on the carbonaceous phyllite samples under 0, 30, 60 different freeze-thaw cycles. The effects of freeze-thaw and cyclic loading on the rock mechanical parameters and deformation were studied. Based on energy calculation, the energy evolution law of rocks with different freeze-thaw cycles under dynamic load was analyzed. Finally, the failure modes of rocks under static load and freeze-dynamic coupling were compared and analyzed from macro and micro perspectives, and the corresponding failure modes were revealed. The results are as follows: ① Compared with the compressive strength of static load, the strength of rock under the combined action of freeze-thaw and cyclic load is significantly reduced, and it shows obvious plasticity. Meanwhile the more freeze-thaw cycles, the more significant the phenomenon; ② With the increase of freeze-thaw cycles, the elastic modulus will gradually decrease and the Poisson's ratio will gradually increase; ③ During the cyclic process, the axial and hoop irreversible strains increase gradually, and the strain increments of both are the largest in the initial cycle of each level of stress and then decrease gradually, while the irreversible volume strain increases first and then decreases, that is, the volume is mainly compacted first and then gradually transformed into expansion; ④ The rock is mainly composed of elastic energy, and the proportion of dissipated energy decreases rapidly in the first cycle and increases stepwise in the subsequent cycle and then tends to be stable; ⑤ From the perspective of macro and micro analysis, the failure mechanism of monotonic loading and cyclic loading is different, but both are the shear failure of inclined section, but the degree of cyclic loading and unloading is greater.

     

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