基于3D-DIC的预制双孔洞大理岩应变场演化规律研究

Strain Field Evolution Law of Prefabricated Double-Holes Marble Based on 3D-DIC

为了研究预制孔洞对大理岩力学性质的影响,预制两组含不同孔洞的大理岩试样进行对比试验:第一组为S型,保持两孔洞D1、D2的直径大小相同,并改变孔洞直径大小;第二组为D型,改变单个孔洞D1的直径大小,保持孔洞D2的直径不变。通过单轴压缩试验并结合3D-DIC技术,得到大理岩试件在不同压缩试验阶段的最大主应变演化云图,分析不同孔洞大理岩破坏过程中裂纹萌生、扩展规律。试验结果表明:随着孔洞直径增大,S型试样的峰值应力与弹性模量降低,D型试样的峰值应力与弹性模量先增大后降低;S型试样产生的裂纹以拉伸裂纹为主,应变集中与裂纹主要发生在D1孔洞附近,D型试样产生的裂纹以拉-剪裂纹为主,应变集中与裂纹主要发生在D2孔洞附近;S型试样破坏模式为拉伸破坏,D型试样随着D1孔洞直径的增大,破坏模式由剪切破坏变为拉伸破坏。

In order to study the effect of prefabricated holes on the mechanical properties of marble,two sets of marble samples with different holes were prefabricated for comparative testing.The first group was S-shaped,with the diameter of the two holes D1 and D2 the same,and the diameter of the holes was changed.The second group was D-shaped,changing the diameter of the single hole D1,while keeping the diameter of hole D2 unchanged.By combining uniaxial compression tests with 3D-DIC technology,the maximum principal strain cloud maps of marble samples at different compression test stages were obtained,and the crack initiation and propagation laws during the failure process of marble with different holes were analyzed.The test results show that as the hole diameter increases,the peak stress and elastic modulus of the S-shaped sample decrease,while the peak stress and elastic modulus of the D-shaped sample first increase and then decrease.The cracks generated by the S-shaped sample are mainly tensile cracks,strain concentration and cracks mainly occur near the D1 hole,while the cracks generated by the D-shaped sample are mainly tensile-shear cracks,and strain concentration and cracks mainly occur near the D2 hole.The failure mode of the S-shaped sample is tensile failure,while the failure mode of the D-shaped sample changes from shear failure to tensile failure as the diameter of the D1 hole increases.