恒定法向刚度边界下含陶粒砂砂岩裂隙剪切力学特性研究  

Shear mechanical behaviors of ceramic proppant-infilled sandstone fractures under constant normal stiffness boundary conditions

作　　者：王刚[1,2] 王鹏举 王长盛 蒋宇静 栾恒杰[4] 黄娜[1] WANG Gang;WANG Pengju;WANG Changsheng;JIANG Yujing;LUAN Hengjie;HUANG Na(Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology,Qingdao 266590,China;College of Civil Engineering,Fujian Institute of Engineering,Fuzhou 350118,China;Graduate School of Engineering,Nagasaki University,Nagasaki 852-8521,Japan;College of Energy and Mining Engineering,Shandong University of Science and Technology,Qingdao 266590,China)

机构地区：[1]山东科技大学山东省土木工程防灾减灾重点实验室,山东青岛266590 [2]福建工程学院土木工程学院,福建福州350118 [3]长崎大学工学研究科,长崎852-8521 [4]山东科技大学能源与矿业工程学院,山东青岛266590

出　　处：《岩土工程学报》2023年第9期1790-1800,共11页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(52079077,52209141);山东省自然科学基金青年项目(ZR2021QE069)。

摘　　要：含支撑剂砂岩裂隙的剪切行为对致密气开采具有重要影响。通过开展不同边界条件下两种粗糙砂岩剪切试验,探究法向应力(1~6 MPa),法向刚度(0~5 GPa/m),初始法向应力(2~6 MPa),支撑剂尺寸(16/30目,20/40目,30/50目)对含陶粒砂砂岩裂隙剪切特性的影响。结果表明:加入陶粒砂后,裂隙面的峰值摩擦角减小,剪切刚度及峰值剪应力降低,并且剪缩量增加,剪胀量减小;随着法向应力的增加,剪切强度提高。在恒定法向刚度(CNS)边界下,随着法向刚度的增加,残余剪应力提高,但峰值剪应力、最终剪胀量和表观摩擦角降低。随着初始法向应力增加,峰值剪应力、残余剪应力及剪切刚度均提高,且变化幅度高于法向刚度的影响;初始法向应力的增加抑制了裂隙面的剪胀,提高了裂隙面的表观摩擦角。随着陶粒砂尺寸的减小,剪切强度提高,剪胀位移增加。The shear behavior of sandstone fractures filled with proppant has an important impact on tight gas production.In this study,the effects of normal stresses(1~6 MPa),normal stiffnesses(0~5 GPa/m),initial normal stresses(2~6 MPa)and proppant sizes(16/30 mesh,20/40 mesh and 30/50 mesh)on the shear behaviors of ceramic proppant-infilled sandstone are revealed through the direct shear tests on two kinds of rough sandstone under the constant normal load(CNL)and constant normal stiffness(CNS)boundary conditions.The results indicate that after adding proppant,the peak friction angle,the shear stiffness and the peak shear stress of fracture decrease,the shear contraction increases and the shear dilation decreases.With the increase of the normal stress,the shear strength increases.Under the constant normal stiffness boundary,with the increase of the normal stiffness,the residual shear stress increases,but the peak shear stress,the final shear dilation and the apparent friction angle decrease.With the increase of the initial normal stress,the peak shear stress,the residual shear stress and the shear stiffness increase,and the variation range is higher than that of the normal stiffness.The increase of the initial normal stress inhibits the shear dilation of the fracture surface,and increases the apparent friction angle of the fracture.With the decrease of the proppant size,the shear strength increases and the dilatancy displacement increases.

关 键 词：恒定法向荷载 恒定法向刚度 支撑剂 砂岩裂隙 剪切特性 

分 类 号：TU432[建筑科学—岩土工程]