非饱和石灰改良膨胀土的持水及强度特性试验研究

Experimental Study on Water-holding and Strength Characteristics of Unsaturated Lime-treated Expansive Soils

采用压力板仪和GDS非饱和三轴试验系统,对广西的非饱和石灰改良膨胀土的持水特性和强度特性进行了研究.对试验结果进行拟合,得到了不同石灰掺量和压实度条件下改良膨胀土的土-水特征曲线,探明了两者对改良膨胀土的持水特性的影响规律.通过非饱和三轴排水剪试验,探明了基质吸力对改良土应力-应变关系的影响规律.研究表明,随着石灰掺量增加,试样的偏应力峰值与残余含水率增大,进气吸力值相应降低.同时,随着土样压实度的增加,其进气吸力值增加,而残余含水率降低.改良后的膨胀土,应力-应变曲线均表现为应变软化型,试样的抗剪强度随基质吸力的增加而增加.

The water holding and strength characteristics of unsaturated expansive soils in Guangxi improved by mixing lime have been studied,through using pressure plate instrument and GDS triaxial test system for unsaturated soils.The soil-water characteristic curves of the improved expansive soils with different lime contents and different compaction degrees have been obtained,then investigated the influence laws of lime contents and compaction degrees on soil-water characteristics of improved expansive soils.Similarly,the effects of matric suction on the stress-strain relations of the improved expansive soil also have been investigated.The research results show that the peak value of the deviatoric stress and the residual moisture content is increased but the value of air-entry suction is decreased with the increasing of lime content.Meanwhile,the value of air-entry suction is increased but the residual moisture content is decreased with the increasing of compaction degrees of soil samples.The results demonstrate that the stress-strain curves of expansive soil with different lime content are fitted strain-softening model.The shear strength of soil samples is increased with the increasing of matric suction.