冻融循环下含预制缺陷3D打印岩石细观结构演化及力学损伤特性研究  

Investigation on the Micro-structure Evolution and Mechanical Damage Characteristics of 3D Printed Rock with Prefabricated Defects under Freeze-Thaw Cycles

作　　者：黎圣君 汪尧 郑原树 何潇 LI Shengjun;WANG Yao;ZHENG Yuanshu;HE Xiao(School of Civil Engineering and Architecture,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China;Shock and Vibration of Engineering Materials and Structures Key Lab of Sichuan Province,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China)

机构地区：[1]西南科技大学土木工程与建筑学院,四川绵阳621010 [2]西南科技大学工程材料与结构冲击振动四川省重点实验室,四川绵阳621010

出　　处：《西南科技大学学报》2024年第4期73-82,共10页Journal of Southwest University of Science and Technology

基　　金：四川省自然科学基金(2022NSFSC1161);西南科技大学博士基金(20zx7129)。

摘　　要：岩石的冻融破坏是导致寒区在役岩土工程结构稳定性丧失与破坏的重要因素。岩石宏观冻融破坏往往经历了细观层面微裂纹萌生、发展、聚并、贯通的损伤过程,即在冻融循环条件下岩石初始缺陷(孔-裂隙结构)在周期性冻胀力作用下发生的疲劳损伤。为探究含有初始缺陷的3D打印岩石在冻融循环作用下的细观结构演化和力学性能劣化特征,通过单轴压缩试验和SEM成像测试,分析了不同冻融条件下3D打印岩石力学性质劣化特征以及细观结构演化规律。采用CT扫描三维重构技术获取和重构了样品的等效孔隙网络模型,定量分析样品的孔隙率、渗透率、孔喉数量等细观结构参数随冻融次数的变化规律,建立了以孔隙结构参数定义的冻融损伤变量,分析了冻融损伤变量随冻融次数增长的演化规律。结果表明:预制裂缝的存在会显著增加3D打印岩石的脆性,随着冻融次数增加,在循环冻胀作用的影响下,砂粒之间的原始胶结受到破坏,微裂纹开始萌生,颗粒排列逐渐由均匀变得无序,孔隙数量和尺寸均表现为增大。冻融损伤变量的发展经历了缓慢增加-平稳增长-快速发展3个阶段。本研究成果为揭示冻融循环条件下岩石宏观力学性质劣化与细观结构演化之间的内在关系和冻融破坏机制提供了一种无损、定量的研究方法,能够为寒区岩土工程冻融破坏防治提供理论指导。Freeze-thaw damage of rocks is a significant factor leading to the loss of stability and destruction of in-service geotechnical engineering structures in cold regions.Macroscopic rock failure often goes through a damage process of micro-crack initiation,development,coalescence,and penetration at the microscale,which is the fatigue damage that occurs to the rock’s initial defects(pore-fracture structure)under the action of cyclical freeze-thaw expansion forces.To investigate the microstructural evolution and mechanical property degradation characteristics of 3D printed rocks with initial defects under freeze-thaw cycles,uniaxial compression test and SEM imaging test were conducted to analyze the mechanical property degradation characteristics and microstructural evolution patterns of 3D printed rocks under different freeze-thaw conditions.The CT scanning three-dimensional reconstruction technology was used to obtain and reconstruct the equivalent pore network model of the samples,and the variation of the microstructural parameters such as porosity,permeability,and pore throat number of the samples with the number of freeze-thaw cycles were quantitatively analyzed.A freeze-thaw damage variable defined by pore structure parameters was established,and the evolution rule of the freeze-thaw damage variable with the increase of freeze-thaw cycles was analyzed.The results show that the presence of prefabricated cracks significantly increases the brittleness of 3D printed rocks.With the increase of freeze-thaw cycles,the original cementation between sand grains is destroyed under the influence of cyclical freeze-thaw expansion,micro-cracks begin to initiate,the arrangement of particles gradually becomes disordered,and both the number and size of pores increase.The development of the freeze-thaw damage variable goes through three stages:slow increase,stable growth,and rapid development.The research findings of this paper provide a non-destructive and quantitative research method for revealing the intrinsic relationship b

关 键 词：3D打印 冻融循环 CT扫描 细观结构 损伤变量 

分 类 号：TU528.1[建筑科学—建筑技术科学]