摘要
为研究深埋隧道在钻爆法开挖时的岩体裂纹扩展规律,建立了2个由多个水泥砂浆试块组成的可模拟节理分布和施加不同应力的组合模型,分别命名为模型1和模型2,模型尺寸为180 cm ×80 cm×25 cm(长×宽×高),其中,母体尺寸为60 cm × 80 cm × 25 cm,母体两侧分别为单条节理和多条节理块体,通过施加不同静应力,分析了9次累计爆破产生的动荷载对砂浆试块母体沿静加载方向裂纹扩展的影响.结果表明:当静应力从0.5 MPa增加到5 MPa时,两个模型上表面都产生了沿静应力加载方向的裂纹,其主裂纹扩展方向与静应力加载方向之间形成了夹角,且裂纹长度大于60 cm,在模型1底部形成了爆破漏斗轮廓,直径约30 cm,未脱落,而模型2底部形成了直径约52 cm、深10 cm的漏斗,且漏斗已脱落.数值分析验证了不同静应力对爆破裂纹扩展方向有导向作用,与模型试验结果完全一致,所不同的是数值计算的主裂纹长度小于模型试验的裂纹长度,分析了造成这种偏差的原因.
Abstract
To investigate the rock mass crack propagation pattern in deep-buried tunnels during drilling and blasting excavation,two combined model tests(labeled as Model 1 and Model 2)consisting of multiple cement mortar blocks were carried out.The dimensions of the models were both 180 cm x 80 cm x25 cm(length width height).A-mong them,the matrix size was 60 cm × 80 cm × 25 cm,and two sides had single and multiple joints.Furthermore,a thorough analysis was conducted to determine the influence of dynamic loads stemming from nine cumulative explo-sions on the crack propagation in a matrix by applying various static stresses,particularly on the direction of the ap-plied static loading.The experimental results reveal that cracks emerge on both Model 1 and Model 2 surfaces along the direction of static stress loading when the static stress increases from 0.5 MPa to 5 MPa.The crack propagation direction forms an angle on the loading direction,and the main crack is longer than 60 cm.A blasting funnel contour with about 30 cm diameter is formed on the bottom of Model 1,which does not fall off.In comparison,a funnel with a-bout 52 cm diameter and a 10 cm depth is formed on the bottom of Model 2,which has fallen off.Numerical analysis verified that the static stress has a guiding effect on the propagation direction of blasting cracks,which is consistent with the model test results.The difference was that the length of the main crack calculated by numerical calculation was smaller than that of the model test.Finally,the reason for this deviation was analyzed.
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