不同围压及应变速率下页岩变形及破损特性试验研究

发布时间：2018-05-21 18:39

本文选题：页岩 + 应变率　；参考：《岩土力学》2017年S1期

【摘要】：为揭示围压及应变速率对页岩力学特性的影响规律,对志留统龙马溪组页岩试样开展了不同围压及不同应变率下的三轴压缩力学试验研究。结果表明,围压和应变率对页岩的弹性模量、峰值强度及破裂形态等均具有显著影响,弹性模量和峰值强度均随围压的升高而增加,峰值强度增加的幅度明显大于弹性模量,峰值强度呈线性增加趋势,低围压时应变率从低到高,弹性模量和峰值强度都呈逐渐升高的趋势,两者与应变率对数的关系可用二次多项式描述;随着围压增大,页岩的应变率效应逐渐减弱,在较高高围压(50 MPa)下峰值强度和弹性模量随应变速率增加而增加现象均变得极不显著。对试验后岩样的破坏模式进行分析可知,页岩在低围压高应变率状态下主要是劈裂剪切破坏,随着围压的增加和应变率的减小,试样的破坏由脆性劈裂剪切破坏向单一剪切破坏转变,再逐渐向延性破坏过渡。研究结果对于合理确立页岩力学参数及设计压裂方案具有较好的参考。
[Abstract]:In order to reveal the influence of confining pressure and strain rate on shale mechanical properties, triaxial compression tests were carried out on shale samples of Longmaxi formation in Silurian under different confining pressures and different strain rates. The results show that confining pressure and strain rate have significant effects on the elastic modulus, peak strength and fracture morphology of shale. The elastic modulus and peak strength increase with the increase of confining pressure, and the amplitude of the increase of peak strength is obviously larger than that of elastic modulus. The peak strength increases linearly, the strain rate increases from low to high at low confining pressure, and the elastic modulus and peak strength increase gradually. The relationship between them and the logarithm of strain rate can be described by quadratic polynomial, and with the increase of confining pressure, The strain rate effect of shale decreases gradually, and the peak strength and elastic modulus increase with the increase of strain rate at a higher confining pressure of 50 MPA. Through the analysis of the failure mode of rock samples after test, it is found that shearing failure of shale is mainly in the condition of low confining pressure and high strain rate, and with the increase of confining pressure and the decrease of strain rate, The failure of the specimen changes from brittle split shear failure to single shear failure and then to ductile failure. The results have a good reference for the reasonable establishment of shale mechanics parameters and the design of fracturing scheme.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点实验室;西南科技大学土木与建筑工程学院;中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;
【基金】：重庆大学煤矿灾害动力学与控制国家重点实验室开放基金(No.2011DA105287 FW201404) 重庆市博士后特别资助(No.Xm2016028) 四川省科技支撑计划项目(No.2016GZ0157) supported by the National Nature Science Foundation of China(51604044)~~
【分类号】：TU45

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