干湿循环对不同粒径组崩解性砂岩改良膨胀土的影响  

Influences of wetting-drying cycles on expansive soils improved with disintegrated sandstone with different particle size groups

作　　者：李国维[1,2] 王佳奕 陈伟[1,3] 吴建涛[1,2] 曹雪山[1,2] 吴少甫[4] LI Guo-wei;WANG Jia-yi;CHEN Wei;WU Jian-tao;CAO Xue-shan;WU Shao-fu(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210024,China;Highway and Railway Research Institute,Hohai University,Nanjing 210024,China;Geotechnical Research Institute,Hohai University,Nanjing 210024,China;China Railway 20th Bureau Group Co.,Ltd.,Xi'an 710016,China)

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210024 [2]河海大学道路与铁道工程研究所,江苏南京210024 [3]河海大学岩土工程研究所,江苏南京210024 [4]中铁二十局集团有限公司,陕西西安710016

出　　处：《岩土工程学报》2022年第4期643-651,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(41472240)。

摘　　要：基于引江济淮工程研究利用河道开挖弃料崩解性砂岩改良膨胀土的长期效果。试验结果表明:①崩解性砂岩改善膨胀土的压实性和强度特性,岩屑粒径小于2 mm时改良土的压实性最优,砂岩物理改良土的直剪指标与岩屑粒径正相关,砂岩水泥复合改良土的直剪指标主要受水泥改良作用控制,岩屑粒径的影响不明显;②崩解性砂岩对改良土干湿循环过程中的开裂具有抑制作用,砂岩物理改良土中岩屑粒径大于10 mm时其周围土中会出现裂隙集中现象,砂岩水泥复合改良土的裂隙率明显小于纯水泥改良土,与岩屑尺寸无显著相关性;③崩解性砂岩具有延缓改良土在干湿循环过程中凝聚力衰减的作用,延缓作用受岩屑尺寸影响,岩屑粒径在砂岩物理改良土中应不大于10 mm,在砂岩水泥复合改良土中应不大于5 mm;④崩解性砂岩微观上的演化特征影响改良土宏观上的裂隙发育和强度衰减规律。Based on the project of diverting water from Yangtze River to Huaihe River,the long-term effect of the improved expansive soils with disintegrated sandstone waste from river excavation is studied.The results show that:(1)The disintegrated sandstone improves the compactness and strength characteristics of the expansive soils.The improved expansive soils have the best compactness when the particle size of the disintegrated sandstone is less than 2 mm.The direct shear index of the physically improved soils is positively correlated with the particle size of the sandstone.The direct shear index of the compositely improved soils is mainly controlled by the improvement of cement,and the influences of particle size of the sandstone is not obvious.(2)The disintegrated sandstone can inhibit the cracking of the improved expansive soils during wetting-drying cycles.When the particle size of the sandstone is larger than 10 mm,there will be crack concentration in the surrounding soils.The crack rate of the compositely improved soils is significantly lower than that of the cement-improved soils,and has no significant correlation with the particle size of the sandstone.(3)The disintegrated sandstone has the effect of delaying the cohesion attenuation of the improved soils in the process of wetting-drying cycles,and the effect is affected by the particle size of the sandstone.The particle size of sandstone shall not be greater than 10 mm in the physically improved soils and 5 mm in the compositely improved soils.(4)The microscopic evolution characteristics of the disintegrated sandstone affect the macroscopic crack development and strength attenuation of the improved soils.

关 键 词：膨胀土 崩解性砂岩 粒径 干湿循环 微观机理 

分 类 号：TU452[建筑科学—岩土工程]