朱子涵, 蔚立元, 李景龙, 等. 峰前卸荷大理岩变形演化规律及破坏耗能特征[J]. 煤炭学报, 2020, 45(S1): 181-190. DOI: 10.13225/j.cnki.jccs.SJ20.0122
引用本文: 朱子涵, 蔚立元, 李景龙, 等. 峰前卸荷大理岩变形演化规律及破坏耗能特征[J]. 煤炭学报, 2020, 45(S1): 181-190. DOI: 10.13225/j.cnki.jccs.SJ20.0122
ZHU Zihan, YU Liyuan, LI Jinglong, et al. Deformation evolution and dissipated energy characteristicsof marble under pre-peak unloading conditions[J]. Journal of China Coal Society, 2020, 45(S1): 181-190. DOI: 10.13225/j.cnki.jccs.SJ20.0122
Citation: ZHU Zihan, YU Liyuan, LI Jinglong, et al. Deformation evolution and dissipated energy characteristicsof marble under pre-peak unloading conditions[J]. Journal of China Coal Society, 2020, 45(S1): 181-190. DOI: 10.13225/j.cnki.jccs.SJ20.0122

峰前卸荷大理岩变形演化规律及破坏耗能特征

Deformation evolution and dissipated energy characteristicsof marble under pre-peak unloading conditions

  • 摘要: 变形是岩石卸荷破坏过程中的重要特征,岩石中积聚能量的耗散则是卸荷破坏的本质。利用MTS 815.3岩石力学试验系统探究大理岩在峰前卸荷条件下的变形演化规律及破坏耗能特征,主要考虑了应力路径、卸荷速率和卸荷点等因素的影响。结果表明:围压卸至0处体积应变为正时,可制备卸荷损伤破裂岩样,体积应变在卸荷过程中分为3个阶段:稳定阶段、缓慢减小阶段和显著扩容阶段;卸荷过程中,剪胀角与卸荷点呈正相关;变形模量(或广义泊松比)先缓慢减小(增加),随后快速降低(增加),卸荷点越大变形模量(或广义泊松比)转折点处对应的围压越大,卸荷路径对变形模量和广义泊松比影响较小;耗散能与卸荷点呈正相关,升轴压卸围压耗散能>恒轴压卸围压>卸轴压卸围压;不同卸荷路径下吸收能和耗散能随卸荷速率的增加差值逐渐减小,趋于稳定的吸收能和耗散能大小约0.27 MJ/m3和0.16 MJ/m3;卸荷速率控制试样破坏形态,低卸荷速率下,破坏形态以张拉剪切为主,破坏试样表面张拉裂纹和环向裂纹显著;较高卸荷速率下,表面张拉裂纹减少,破坏形式主要为伴随岩块崩落的剪切破坏;卸荷路径和卸荷点对岩样的破坏程度起作用,其中升轴压破坏程度>恒轴压>卸轴压,且与卸荷点呈正相关。

     

    Abstract: During the rock unloading failure process,the deformation evolution is an important feature and the dissipation of accumulated energy in the rock is the essence of unloading failure. The deformation and energy evolution characteristics of marble are studied based on MTS815.3 testing system in terms of three unloading paths,three unloading rates and three unloading points. The results show that the unloaded damaged rock samples can be obtained when the volumetric strain is positive when the confining pressure is 0. The volumetric strain is divided into three stages during the unloading process:the stabilization phase,the slow reduction phase and significant expansion phase. The dilatancy angle is positively correlated with the unloading point during unloading process. The deformation modulus (generalized Poisson's ratio) decreases (increases) slowly first,then decreases (increases) rapidly in the test. The larger the unloading point,the larger the deformation modulus (generalized Poisson's ratio) is and the unloading paths have no significant effect on the deformation modulus and generalized Poisson's ratio. Dissipative energy is positively correlated with unloading point. The absorption energy and dissipation energy of different unloading paths decrease with the increase of the unloading rate,and eventually stabilize. The final absorption and dissipation energy are about 0.27 MJ/m3 and 0.16 MJ/m3. The failure mode is mainly controlled by the unloading rate. When the unloading rate is from low to high,the failure mode of the specimen changes from tensile shear failure to shear failure accompanied with spalling.Unloading points and unloading paths play a role in the degree of rock fracture. The research conclusions have a certain reference value for the excavation of deep caverns and the optimization of support schemes.

     

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