振动荷载下不同级配的基床粗粒土填料孔隙连通性特征研究
Connectivity characteristics of internal pores of unbound embankment fill materials with different gradations subjected to vibration loading
摘要
Abstract
Unbound granular fill(UGF)materials are commonly compacted during vibration compaction to construct railway embankments and rolling,but,the quantitative gradation effects affecting the connectivity characteristics of three-dimensional(3D)internal pore structures and related seepage performance are barely understood.To address this deficiency,laboratory UGF specimens were prepared with three different gradations(i.e.,G/S(mass ratio of stony and sand)is 1.0,1.8,2.5)designed based on particle packing theory and then compacted by the newly developed vibratory plate compactor.The dry-density optimal vibratory parameters combination were determined accordingly.The UGF specimens compacted with such optimal parameters combination were scanned by the X-ray computer topography(XCT)equipment and reconstructed their 3D models.The connectivity characteristics of 3D internal pores were quantified by using the image processing techniques and the maximum ball algorithms.The seepage characteristics of such UGF specimens with different gradations were simulated and comparatively analyzed.The results show that the vibratory parameters combination includes 25 Hz frequency,1.4 kN force,and at least 60 s duration when the dry density of specimen is the best.As the gradation parameter G/S increases,the throat length and radius of internal pores increase,the quantities of intermediate and largesized pores increase,and the average pore radius increases.The pore-throat ratio can better quantify permeability performance,i.e.,as it increases,the average coordination number of internal pores increases,their throats become longer,and their radius become bigger,and pore connectivity thus improves.The G/S influences the radius,throat length and connectivity of 3D pores,and furtherly governs seepage velocity,i.e.,as G/S increases,the throats of internal pores transition from thin and elongated to thick and short until the thick and long seepage paths are formed.The gradations with greater G/S are recommended for desired internal pore connectivity and permeability under the premise that the compaction quality and deformation stability are satisfied.关键词
基床粗粒土填料/级配/孔隙/连通性/XCT扫描/渗流模拟/渗透性能Key words
unbound granular embankment fill materials/gradation/pores/connectivity/X-ray computer topography(XCT)scanning/seepage simulation/permeability performance分类
交通工程引用本文复制引用
王萌,于群丁,肖源杰,华文俊,李文奇..振动荷载下不同级配的基床粗粒土填料孔隙连通性特征研究[J].中南大学学报（自然科学版）,2023,54(11):4436-4448,13.基金项目
国家自然科学基金资助项目(52178443,51878673,U1934209) （52178443,51878673,U1934209）
国家重点研发计划项目(2019YFC1904704) （2019YFC1904704）
中国铁道科学研究院科技研究开发计划重大课题(2020YJ022 （）
2019YJ026) （）
重载铁路工程结构教育部重点实验室(中南大学)开放课题(2021JZZ01,2021JZZ02,2022JZZ03) （中南大学）
中南大学研究生自主探索创新项目(2021zzts0788,2021zzts0227,2021zzts0223)(Projects(52178443,51878673,U1934209)supported by the National Natural Science Foundation of China （2021zzts0788,2021zzts0227,2021zzts0223）
Project(2019YFC1904704)supported by the National Key R&D Program of China （2019YFC1904704）
Projects(2020YJ022,2019YJ026)supported by the Key R&D Program of Chinese Academy of Railway Sciences （2020YJ022,2019YJ026）
Projects(2021JZZ01,2021JZZ02,2022JZZ03)supported by the Open Foundation of MOE Key Laboratory of Engineering Structures of Heavy Haul Railway(Central South University) （2021JZZ01,2021JZZ02,2022JZZ03）
Projects(2021zzts0788,2021zzts0227,2021zzts0223)supported by the Graduate Free Exploration Programt of Central South University) （2021zzts0788,2021zzts0227,2021zzts0223）
