非饱和填土侧限压缩变形特性试验研究及应用初探  

Experimental study and preliminary application on the confined compressive deformation characteristics of unsaturated filling soils

作　　者：张沛然[1] 黄雪峰[1,2] 扈胜霞[3] 杨校辉[1] 

机构地区：[1]兰州理工大学土木工程学院,甘肃兰州730050 [2]解放军后勤工程学院土木工程系,重庆401311 [3]延安大学建筑工程学院,陕西延安716000

出　　处：《岩土力学》2018年第2期437-444,共8页Rock and Soil Mechanics

基　　金：陕西省科技统筹创新工程计划课题(No.2012KTDZD03-04);国家自然科学基金(No.51309199)~~

摘　　要：为研究吸力及压实度对非饱和压实填土压缩变形特性的影响,并建立脱湿(吸力增长)状态下的填方土体工后沉降变形修正计算应用模型,开展了控制吸力和压实度的一维非饱和土侧限压缩试验。结果表明:压缩曲线平缓段随压实度和吸力的提高而增长,表明土样的结构屈服强度同步得到提高;在比容v变化差值序列上,饱和土压缩土样最大、常规压缩土样次之、脱湿土样最小,并且吸力越大,比容v变化差值越小。经历脱湿(吸力增长)后的压实土压缩性降低,定义和建立了吸力压缩系数m_s及其经验模型,用以表征和度量吸力和压实度对压缩特性的影响规律及程度,发现m_s随竖向应力增加呈现指数型衰减。对模型参数与压实土相关参量间的关联性进行了分析探讨,同一压实度土样不同吸力所对应的参数α均值随压实水平提高而线性减小,参数λ总体上随吸力的增加而增大,但随压实度的提高吸力对于土体抗压性增强的贡献水平降低且参数l试验数值点靠拢线性趋近线,土样的压缩性随压实度和吸力大小变化而动态调整。基于分层总和法的基本原理初步构造建立了高填方非饱和填土压缩变形修正计算模型(MS),其应用途径应建立在进一步对非饱和压实填土受荷状态下脱湿土-水特征关系的研究基础之上。To study the influence of suction and degree of compaction on the deformation of unsaturated filling soils, one-dimensional confined compression test of unsaturated soil was carried out to control suction condition and degree of compaction. Results show that the gentle stage of the compressive curve extends with the increase of compaction and suction, indicating the synchronously improved yield strength of soil samples. The saturated soil sample has the largest difference of the specific volume v during the test, and the dehydration soil sample changes the smallest. The greater the suction is, the smaller the difference of specific volume v is. Compressibility of compacted soil decreases after dehydrating or suction growth. The suction compressibility coefficient and its empirical model are defined and established to characterize the influence of suction and compaction on compressive characteristics and measure the influence degree. It is found that the model exhibits exponential decay with increasing the vertical stress. The relationship between the parameters of the model and relevant parameters of compacted soil are analyzed and discussed. The average value of the parameters corresponding to the different suctions of the same compacted soil sample decreases linearly with the increase of compaction level. The parameters generally increase with the increase of suction. However, with the increase of compaction degree, the contribution of suction to the compressive strength decreases and the experimental value point is close to the linear approaching line. The compressibility of soil samples is adjusted dynamically with the change of compaction and suction. Based on the basic principle of the layered summation method, a modified calculation model for the compressive deformation of the high fill unsaturated filling soils （MS） is established. The application of this model should be established on the study of the relationship between soil and water of unsaturated compacted filling soils on the loading state.

关 键 词：非饱和土 压实度 吸力 荷载 压缩变形 压缩系数 

分 类 号：TU411[建筑科学—岩土工程]