初始损伤对脆性岩石抗压力学性质的影响

来源期刊:中南大学学报(自然科学版)2017年第2期

论文作者:陈积光 陈乐求 张家生 陈俊桦

文章页码:484 - 491

关键词:岩石;损伤;单轴抗压强度;弹性模量;脆性破坏

Key words:rock; damage; uniaxial compressive strength; elastic modulus; brittle failure

摘    要:基于现有各向同性损伤本构理论,提出岩石初始损伤定义及其计算方法。初始损伤表示为加载前的损伤岩石弹性模量相对无损岩石弹性模量的劣化程度。对不同初始损伤的玄武岩试样进行单轴抗压试验,定量分析初始损伤对玄武岩的应力与应变关系、强度、破坏应变、初始泊松比和应变软化性质等的影响,给出单轴抗压强度、初始泊松比等力学参数随初始损伤变量变化的规律及拟合公式。研究结果表明:只有当岩石初始损伤超过损伤门槛值即无损岩石破坏时对应的损伤值时,岩石抗压强度随初始损伤增大而显著减小;与峰值应力对应的应变随初始损伤增大而近似呈线性增大趋势;岩石初始泊松比随初始损伤增大近似呈指数增大;初始损伤越小,应力峰值后的岩石破坏越显脆性。

Abstract: The initial damage definition for rock and the method were presented based on current isotropic damage constitutive model. The initial damage was expressed as the inferiority degree of the initial modulus of rock compared with the undamaged modulus. The uniaxial compressive tests for basalt with different initial damages were carried out. The influences of initial damage of rock on the relationship among the uniaxial compressive stress and the uniaxial compressive strain, the uniaxial compressive strength, the failure strain, the initial value of Poisson''''s ratio, the strain softening, and so on, were quantitatively analyzed. The rule and fitting formula about the mechanical parameters (including the change of the uniaxial compressive strength, the initial Poisson ratio, and so on) changing with the initial damage of rock were presented. The results show that only their initial damage value surpasses the damage threshold value which is corresponding to the peak stress of undamaged rock under uniaxial compressive loading, and the uniaxial compressive strength of initial damage rock samples decreases significantly with the increment of the initial damage. The strain corresponding to the peak stress increases almost linearly with the increment of the initial damage. The initial Poisson ratio shows exponential growth with the initial damage. The brittle failure after peak stress is remarkable with the decrement of the initial damage of rock.

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