摘要
黄河下游冲淤积在山东省形成了大量特殊的高液限黏土,由于沿线平原区路基填料极度匮乏,若弃之不用将造成极大损失.本文从施工期和运营期2个阶段对土体的强度和模量进行了试验探讨.黄泛区高液限黏土主要由高含量的磨圆粉粒及黏粒组成,高于最优含水率压实时,土体表现出空气体积率低、饱和度高的特点.基于滤纸试验,发现高进气值导致土体具有很强的持水性.基于不排水、不排气的三轴试验,获得了不同压实状态下土体归一化静强度和抗剪强度指标与饱和度、空气体积率的相关关系.该类土存在的最优饱和度为79%(相应空气体积率为8%).相较于土体的强度特征,黄泛区高液限黏土回弹模量受含水率的影响更敏感,含水率由20%增加至23%时,尽管路基依然保持稳定,但回弹模量的大幅衰减导致路基压缩应变增加近200%.结合我国和日本的路基压实控制标准,提出黄泛区高液限黏土的填筑含水率不应高于23%,空气体积率不高于8%(即压实度控制在90%及以上),以保证土体强度和模量的长期稳定性.
Large area of special high liquid limit clay was formed due to the depositing in the downstream of Yellow River at Shandong province.Without the use of such clay in those plain areas in lack of filling materials,great resource waste would be caused.This paper experimentally examined the soil strength and modulus in both construction and operation periods.The high liquid limit clay in Yellow River flood area consisted of higher rounded silt particle and clay particle,which presented low volume ratio of air and high saturation degree when compacted above the optimum moisture content.Based on the filter paper tests,it was indicated that high air intake value resulted in strong water retention capacity.Through the unventilated-undrained triaxial test,the relationships between the normalized static strength,shear strength and saturation degree/volume ration of air were obtained at different compaction states.It was found that the soil had an optimum saturation ratio at 79%(volume ratio of air=8%).The soil resilient modulus was more sensitive to the moisture contents.Although the subgrade remained safe when moisture contents increased from 20%to 23%,the compression strain increased by almost 200% due to the sharp decrease in the resilient modulus.Considering the subgrade compaction standard specified in China and Japan,the high liquid limit clay in Yellow River flood area should be compacted lower than 23%moisture content and 8% volume ratio of air,i.e.,no less than 90%compaction degree,to ensure the long-term stability of soil strength and modulus.
作者
蒋红光
曹让
马晓燕
陈思涵
陈鲁川
姚占勇
JIANG Hongguang;CAO Rang;MA Xiaoyan;CHEN Sihan;CHEN Luchuan;YAO Zhanyong(School of Qilu Transportation,Shandong University,Jinan 250061,China;Road Bureau,Shandong Provincial Department of Transport,Jinan 250002,China;Qilu Transportation Development Group,Jinan 250101,China)
出处
《湖南大学学报(自然科学版)》
EI
CAS
CSCD
北大核心
2019年第11期154-163,共10页
Journal of Hunan University:Natural Sciences
基金
国家自然科学基金青年基金资助项目(51608306)
软弱土与环境土工教育部重点实验室(浙江大学)开放基金资助项目(2017P01)
山东省交通厅科技发展计划项目(2011Y16,2016B21)
教育部博士后科学基金项目(2016M590636)
山东大学基本科研业务费专项资金资助项目(2016GN026)~~
关键词
黄泛区高液限黏土
持水能力
饱和度
空气体积率
抗剪强度
回弹模量
high liquid limit clay in Yellow River flood area
water retaining characteristics
saturation degree
volume ratio of air
shear strength
resilient modulus