含油率影响下油页岩力学性质与破坏断裂特征研究

Research on the Characteristics of Oil Shale Mechanics and Destruction Fracture under the Influence of Oil Content

油页岩的含油率存在巨大差异,这种含油率的变化会引起其力学性质与破坏断裂特征的差异。选取含油率为6.5%、6%、5%和3%的垂直层理油页岩试样,对其开展单轴压缩实验、场应变与声发射监测。研究发现:含油率的提升会降低油页岩抗压强度,并使其由脆性向延性转变。高含油率油页岩易发生剪切—张拉破坏;低含油率油页岩破坏模式偏向于张拉破坏。加载过程中,油页岩试件主应变场由均匀分布向应变集中分布转变,垂直层理油页岩的应变场更容易形成多条平行应变集中条带,当含油率不断降低时,主应变场变化过程中的剪切现象减弱。高含油率的试样振铃计数表现为阶梯型增长,破坏后,依然出现了较高的振铃计数;低含油率油页岩只在破坏时出现较高的振铃计数。相同弹性能条件下,低含油率油页岩在储能阶段的变形更小。高含油率试样具有一定延性,在试样到达应力峰值点后,弹性能并没有完全释放,仍保留一部分弹性能。低含油率试样的抗变形能力较强,所以,在相同应变条件下,其耗散的能量更高。

There is a huge difference in oil content of oil shale,and this change in oil content will cause differences be-tween their mechanical properties and destructive breakdown characteristics.Select vertical oil shard samples with a oil content of 6.5%,6%,5%,and 3%.It carried out a single-axis compression experiment,field strain and acoustic emission monitoring.Studies have found that the increase in oil content will reduce the pressure resistance of oil shale and transform it from crispy to delay.High oil-content oil shale is prone to shear-tensor damage.Low oil-content oil shale destruction mode is biased towards tensor damage.During the loading process,the main strain field of the oil shale is transformed from a uniform distribution to a concentrated distribution.The shear phenomenon in the field change weakened.A high oil-content sample ringing count is the growth of the stepped type.After the damage,there is still a high ringing count.The high ringing count of low oil-content oil shale occurs only when it is destroyed.Under the same elasticity conditions,the deformation of low oil-content oil shale in the energy storage stage is smaller.The high oil-content sample has a certain delay.After the sample reaches the peak of the stress,the elasticity is not fully released,and some elasticity is still retained.Low oil-content samples have strong anti-deformation ca-pacity,so under the same strain conditions,their scattered energy is higher.