基于CT-三轴试验的珊瑚砂试样细观孔隙结构演化特性  

Evolution characteristics of mesoscopic pore structure for coral sand samples based on CT-triaxial tests

作　　者：胡丰慧 方祥位 申春妮 姚志华[3] 陈正汉 HU Fenghui;FANG Xiangwei;SHEN Chunni;YAO Zhihua;CHEN Zhenghan(School of Civil Engineering,Chongqing University,Chongqing 400045,China;School of Civil and Hydraulic Engineering,Chongqing University of Science and Technology,Chongqing 401331,China;Department of Airdrome Construction Engineering,Air Force Engineering University,Xi'an 710038,China;Department of Military Installation,Army Logistics University,Chongqing 401311,China)

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆科技大学土木与水利工程学院,重庆401331 [3]空军工程大学机场建筑工程系,陕西西安710038 [4]陆军勤务学院军事设施系,重庆401311

出　　处：《岩土工程学报》2025年第5期936-947,共12页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51978103);重庆英才创新创业示范团队项目(cstc2024ycjh-bgzxm0012)。

摘　　要：孔隙特征及受荷过程中的演化特性对珊瑚砂的物理力学特性有重要影响。利用自主研发的高压土工CT-三轴仪,在保证试样常规尺寸大小的前提下,对珊瑚砂进行围压为100~1600 kPa的三轴固结排水试验,同时在加载过程中对珊瑚砂试样进行实时CT扫描,根据CT图像分析孔隙形状参数球圆度和各向异性,利用数字体积关联法(DVC)分析珊瑚砂的孔隙结构演化特性。结果表明,在围压和颗粒破碎的影响下,加载过程中珊瑚砂试样的孔隙结构演化大致可分为3段,即加载端部位(Ⅰ段)主要受到压力作用,颗粒发生破碎和滑动引起孔隙率减小,局部应变主要为负应变即压应变;试样中部及以下部位(Ⅱ和Ⅲ段),低围压时颗粒滑移孔隙外扩宏观上表现为剪胀现象,局部应变呈现正应变即拉应变,高围压和颗粒破碎会抑制剪胀现象;较好地解释了低围压时砂样的剪切带常发生在试样中间及偏下部分的原因。试样加载过程中孔隙形状随围压增大越来越接近球形和趋于各向同性;沿竖直方向,试样的变形量在围压约束下逐渐减小。试样的孔隙体积和局部应变在加载过程中逐渐稳定,符合砂土的临界状态理论。研究成果对深入认识珊瑚砂的工程力学特性具有重要意义。The evolution characteristics of pore structure during loading have an important influence on the mechanics of coral sand.Using the self-developed high-pressure geotechnical CT-triaxial apparatus,the triaxial consolidated tests on the coral sand with a confining pressure of 100~1600 kPa are carried out under the premise of ensuring the conventional size of samples.The real-time CT scanning of the coral sand samples is carried out during loading.The shape parameters of pores like sphericity and anisotropy are analyzed according to the CT images,and the evolution characteristics of pore structure for the coral sand are analyzed by the digital volume correlation method.The results show that the evolution of pore structure for coral sand samples during the loading process can be roughly divided into three stages under the influences of confining pressure and particle breakage.That is,the loading end(section Ⅰ)is mainly affected by compression,the porosity decreases because of the particle breakage and movement,and the local strain is mainly negative.While in the middle and lower parts of the samples(sections Ⅱ and Ⅲ),the combination of slipping particles and increasing porosity macroscopically shows dilatation at low confining pressure,and the local strain shows positive strain.However,the high confining pressure and particle breakage inhibit dilatation.It is explained that the shear zone of the sand samples often occurs in the middle and lower parts of the samples at low confining pressure.During loading,the pore shape of the samples becomes closer to spherical and isotropic with the increase of confining pressure,and the deformation of the samples increases with the axial strain and gradually decreases under the constraint of high confining pressure.The pore volume and local strain of the samples are gradually stabilized during loading.The research results are of great significance for understanding the engineering mechanical properties of the coral sand.

关 键 词：珊瑚砂 CT扫描 细观孔隙 演化 数字体积关联法DVC 

分 类 号：TU43[建筑科学—岩土工程]