基于CT扫描单轴压缩下注浆体试块裂隙动态演化过程试验研究  

Experimental study of fracture dynamic evolution process of grouting specimen under uniaxial compression based on CT scanning

作　　者：朱昌星[1] 孙家鑫 王彦伟 ZHU Chang-xing;SUN Jia-xin;WANG Yan-wei(School of Engineering,Henan Polytechnic University,Jiaozuo,Henan 454000,China)

机构地区：[1]河南理工大学土木工程学院,河南焦作454000

出　　处：《岩土力学》2022年第9期2493-2503,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51874119);河南省教育厅基金(No.2011A440003);河南理工大学博士基金(No.B2009-96)。

摘　　要：为了研究注浆体在荷载作用下裂隙动态演化过程,以级配砂砾注浆试块为研究对象,利用CT扫描系统对其单轴压缩破坏过程进行阶段性扫描。通过图像重构技术实现注浆体试块内部裂隙结构空间可视化,定量表征裂隙数目和体积等结构特征参数;采用Python编程对CT切片的灰度值和分形维数进行计算,分析试块不同阶段的细观损伤程度。结果表明:整个压缩阶段,注浆体试块内部裂隙体积呈现缓慢上升-缓慢下降-缓慢上升-急速上升趋势,裂隙数目呈现先增大后减小的趋势;裂隙扩展遇到砂砾时,多为绕砾扩展,少数情况出现穿砾扩展,裂隙分叉扩展多发生在水泥基体与砂砾的界面处;按试块内部裂隙演化过程可将破坏分为4个阶段:初始缺陷扩张阶段、压密阶段、裂隙加速扩展阶段和裂隙贯通阶段;试块同一阶段同层切片的损伤变量与分形维数在数值上呈现一定的正相关性,与其裂隙体积演化趋势相似。研究成果可为深入研究注浆体失效过程及裂隙演化规律提供参考依据。To study the fracture dynamic evolution process of grouting specimens under loading conditions,the graded gravel grouting specimen was periodically scanned during the uniaxial compression damage process using a CT scanning system.Based on the image reconstruction technique,the spatial visualization of the fracture structure inside the test grouting specimen block is achieved,and the structural characteristic parameters are characterized quantitatively such as the number and volume of fractures.The gray value and fractal dimension of the CT slices are calculated using Python programming to analyze the mesoscale damage extent at different loading stages of the grouting specimen.It is shown that the specimen’s internal fracture volume shows a trend of slow rise,slow fall,slow rise,and rapid rise.The fracture number shows a trend of increasing firstly and then decreasing during the whole compression stage.When the fracture expansion paths encounter gravel,most of the fractures expand around the gravel location and few fractures expand through the gravel.In addition,the fracture bifurcation expansion mostly appears at the interface between the cement matrix and gravel.The specimen damage process could be divided into four stages in terms of the fracture evolution process inside the specimen:initial defect expansion stage,internal crack compacting stage,fracture expansion stage,and fracture penetration stage.For the slice at the same loading stage of the test specimen,it is found that the value of the damage variable and fractal dimension shows a certain positive correlation,which is similar to the trends of the fracture volume evolution.The research results can provide a reference for the study of the failure process and fracture evolution law of the grouting body.

关 键 词：CT扫描 注浆体 数字重构 裂隙演化 量化表征 

分 类 号：TU452[建筑科学—岩土工程]