基础理论与实验研究

不同围压及应变速率下页岩变形及破损特性试验研究

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  • 1. 重庆大学 煤矿灾害动力学与控制国家重点实验室,重庆 400044;2. 西南科技大学 土木与建筑工程学院, 四川 绵阳 621010; 3. 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,湖北 武汉430071
刘俊新,男,1976年生,双博士后,教授,主要从事岩石力学与渗流力学研究。

收稿日期: 2016-09-17

  网络出版日期: 2018-06-05

基金资助

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)。

Experimental study of mechanical behaviours of shale under different confining pressures and different strain rates

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  • 1. State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China; 2. Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China; 3. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China

Received date: 2016-09-17

  Online published: 2018-06-05

Supported by

This work was supported by the National Nature Science Foundation of China(51604044); Chongqing Postdoctoral Foundation(Xm2016028) and the Sichuan Provice and Technology Support Project(2016G20157).

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。

本文引用格式

刘俊新,张 可,刘 伟,施锡林, . 不同围压及应变速率下页岩变形及破损特性试验研究[J]. 岩土力学, 2017 , 38(S1) : 43 -52 . DOI: 10.16285/j.rsm.2017.S1.005

Abstract

To investigate the mechanical properties of shale under different confining pressures and different strain rates, the triaxial compression experiments of Longmaxi Group shale samples are conducted under different confining pressures and different strain rates. The experimental results show that the confining pressure and strain rate affect obviously elastic modulus, peak strength and fracture morphology of the shale. The elastic modulus and peak strength increase with the increase of confining pressure, the increase of peak strength is significantly greater than thaengtht of the elastic modulus; and the peak strength showed a linear increasing trend. At a low confining pressure, elastic modulus and peak strength gradually increase along with the inclining of strain rate from low to high; the relationship between the two and the strain rate can be described by a biquadratic polynomial. With the increase of confining pressure, the effect of strain rate on the shale is gradually weakened; at a high confining pressure of 50 MPa, the phenomenon of the compressive strength and elastic modulus increase with the increase of strain rate is terminated. Under condition of low confining pressure and high strain rate, the shale is mainly split shear failure; with the increase of confining pressure and the decrease of strain rate, the failure mode would change from split shear failure to single shear failure; and then gradually transits to a ductile fracture. The results of the test have important guiding roles in establishing the mechanical parameters of shale and designing the fracturing program.
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