水泥改良软土次固结变形特性试验研究  

Experimental study on secondary consolidation deformation characteristics of cement modified soft soil

作　　者：贺建清 任虎程[2] 胡惠华 吴昊天 王朦 HE Jianqing;REN Hucheng;HU Huihua;WU Haotian;WANG Meng(Hunan Provincial Key Laboratory of Hydropower Development Key Technology,Changsha 410014,China;Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Hunan University of Science and Technology,Xiangtan 411201,China;Hunan Provincial Communications Planning,Survey&Design Institute Co.,Ltd.,Changsha 410200,China)

机构地区：[1]水能资源利用关键技术湖南省重点实验室,湖南长沙410014 [2]湖南科技大学岩土工程稳定控制与健康监测省重点实验室,湖南湘潭411201 [3]湖南省交通规划勘察设计院有限公司,湖南长沙410200

出　　处：《铁道科学与工程学报》2023年第3期941-949,共9页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52078211);湖南省自然科学基金资助项目(2021JJ30252);湖南省重点实验室开放基金资助项目(PKLHD201903)。

摘　　要：人工配制不同水泥掺量的水泥土,进行一维固结蠕变试验,研究水泥掺量对水泥土次固结特性的影响;测定水泥土吸附结合水含量,确定吸附结合水含量与水泥掺量的关系,探究水泥对软土次固结特性的影响机制。研究结果表明,水泥土的结构强度随着水泥掺入比的增加而增大,水泥掺入比低于10%,其增速缓慢;超过10%,增速明显。水泥土的主固结时间几乎不受固结压力影响,随着水泥掺入比增大明显减小。水泥改良软土的次固结系数C_(α)与固结压力p的关系曲线在结构强度附近存在峰值点,起始阶段,次固结系数随着固结压力增加逐渐增大;超过峰值后,随着固结压力增加先是明显减小,最后逐渐趋近于基本不再变化的常数。施加的固结压力低于水泥土的结构强度时,e-lg t关系曲线近似呈直线,主、次固结界限模糊,主、次固结划分点难以确定;超过水泥土的结构强度时,e-lg t关系曲线呈反S形,固结压力越大,线形特征越明显,主、次固结分界点越清晰。水泥土的次固结系数C_(α)与压缩指数Cc的比值近似为一常数,水泥土的C_(α)/C_(c)值明显低于原状土,几乎不到原状土C_(α)/C_(c)值的一半,C_(α)/C_(c)值与水泥掺入比aw呈线性递减关系。水泥土的吸附结合水含量Wg与水泥掺入比aw呈良好的线性递减关系,水泥掺量增加,吸附结合水含量变小,结合水膜变薄,流变相物质体积占比相应减少,改良后的软土随着流变相物质的减少,整体性质呈现出次固结特性变弱的趋势。Cement soils with different cement contents were artificially prepared.One-dimensional consolidation creep test was carried out to study the influence of cement content on the secondary consolidation characteristics of cement soil.The adsorbed bound water content of cement soil was measured.The relationship between adsorbed bound water content and cement content was determined to explore the influence mechanism of cement on the secondary consolidation characteristics of soft soil.The results show that the structural strength of cement soil increases with the increase of cement mixing ratio.The growth rate is slow when the cement mixture ratio is less than 10%.When cement is added more than 10%,the growth rate is obvious.The main consolidation time of cement soil is almost not affected by the consolidation pressure,and decreases significantly with the increase of cement mixing ratio.Besides,the relationship curve between secondary consolidation coefficient C_(α) and consolidation pressure p of cement-improved soft soil has a peak point near the structural strength,at the initial stage,the secondary consolidation coefficient increases gradually with the increase of consolidation pressure.When the peak value is exceeded,with the increase of consolidation pressure,the consolidation pressure decreases significantly at first and then gradually approaches a constant which is almost unchanged.In addition,when the applied consolidation pressure is lower than the structural strength of cement soil,the e-lg t curve is approximately linear,the boundary of primary and secondary consolidation is fuzzy.The division point of primary and secondary consolidation is difficult to determine.When it exceeds the structural strength of cement soil,the e-lg t relationship curve is anti-S-shaped.At this time,the greater the consolidation pressure is,the more obvious the linear characteristics are,the clearer the demarcation point between primary and secondary consolidation.Moreover,the ratio of secondary consolidation coefficient C_(α)

关 键 词：软土 水泥土 水泥掺入比 次固结特性 影响机制 

分 类 号：TU43[建筑科学—岩土工程]