| 摘要: |
| 【目的】探讨初始干密度、干湿循环作用及膨胀土体应变对黑龙江引嫩工程渠基膨胀土土水特征的影响，为松嫩平原地区膨胀土土体的渗流研究及其非饱和本构模型的建立提供参考。【方法】以黑龙江膨胀土为研究对象，采用高速恒温冷冻离心机，对4种不同初始干密度（1.45，1.53，1.58和1.63 g/cm3）重塑试样及同一初始干密度下1,3,5次干湿循环试样进行恒温冷冻离心试验，同时平行进行4种不同初始干密度下的收缩试验，并对膨胀土进行体应变修正；基于Gardner模型，建立可以考虑体应变及干湿循环影响的土水特征拟合公式。【结果】体应变修正后的土样体积含水率较修正前提高1.4%~2.8%，且基质吸力越高提高的幅度越大；初始干密度为1.45，1.53，1.58和1.63 g/cm3的4种试样的进气值分别为12.42，38.46，52.21和87.19 kPa，说明初始干密度越大进气值越大，且初始干密度越大试样的土水特征曲线越平缓，持水性越好；随循环次数增加，试样的持水性变差，但会在循环3次后趋于稳定；所建立的土水特征拟合公式能够同时描述基质吸力随初始孔隙比（或干湿循环次数）、体积含水率2个因素的变化规律。【结论】初始干密度及干湿循环作用对黑龙江膨胀土的土水特征曲线有显著影响，同时膨胀土自身性质引起的体应变对土水特征曲线影响较大，在分析膨胀土土水特征时要充分考虑以上因素的影响。 |
| 关键词: 黑龙江膨胀土 土水特征曲线 干湿循环 体应变修正 |
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| 基金项目:国家自然科学基金项目（51978572）；“十三五”国家重点研发计划项目（2017YFC0405103）；陕西省重点研发计划项目（2017ZDXM-SF-074）；陕西省水利科技计划项目（2013slkj-10） |
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| Soil water characteristics of expansive soil in Heilongjiang considering volumetric strain and dry-wet cycle |
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ZHAO Jiamin,ZHANG Aijun,NIU Lisi,et al
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| Abstract: |
| 【Objective】This study discussed the influences of initial dry density,dry wet cycle and volume strain change on soil water characteristics of expansive soil in the canal foundation of Heilongjiang diversion project to provide reference for seepage study and establishment of unsaturated constitutive model of swelling soil in the Songnen Plain.【Method】High-speed constant temperature freezing centrifuge was used to conduct constant temperature freezing centrifugal test on remolded samples of Heilongjiang expensive soil with four different initial dry densities (1.45,1.53,1.58 and 1.63 g/cm3) and on samples with same initial dry density after one,three and five dry wet cycles.The shrinkage test was carried out in parallel,and the volume strain change of expansive soil was corrected.Based on Gardner model,a fitting formula of soil water characteristics considering the effect of volume change and dry wet cycle was established.【Result】The volume moisture content of soil sample after volume strain change modification was increased by 1.4%－2.8%,and higher matric suction caused greater increasing range.The air intake values of four samples with initial dry densities of 1.45,1.53,1.58 and 1.63 g/cm3 were 12.42,38.46,52.21 and 87.19 kPa,indicating that higher initial dry density led to greater air intake value,smoother soil water characteristic curve and better the water holding capacity.With the increase of number of cycles,the water holding capacity decreased,but it became stable after three cycles.The established soil water characteristic fitting formula can simultaneously describe the change of matrix suction with initial void ratio (or number of dry wet cycles) and volume moisture content.【Conclusion】Initial dry density and initial dry wet cycle had significant influence on soil water characteristic curve of expansive soil in Heilongjiang.The volume strain change caused by nature of expansive soil had great influence on soil water characteristic curve.These factors should be fully considered when analyzing soil water characteristics of expansive soil. |
| Key words: Heilongjiang expansive soil soil-water characteristic curve dry-wet cycle volume strain correction |
