中文摘要：

半干旱地区石灰改良膨胀土非饱和强度特征研究,对确保膨胀土地基石灰处理工程的合理设计、工程的长期安全运行具有重要实际意义。基于非饱和GDS三轴试验系统和SEM试验及数字图像处理技术,对合肥新桥国际机场工程场地掺石灰7%改良膨胀土的微结构、土水特征曲线（SWCC）和抗剪强度开展试验研究,试图从宏、微观相结合角度探讨非饱和石灰改良膨胀土的强度特征。研究得出石灰改良膨胀土的微观结构以粒状颗粒为主,剪切破坏面上的土体微孔隙直径主要为0.52-7.80μm,面积大多小于4μm^2,实测吸水过程的SWCC较脱水过程曲线存在明显的滞后现象,且进气值大于原状膨胀土值;相同围压下灰土的抗剪强度峰值、残余强度值随着吸力的增大而增大;对吸力相同,残余强度则随围压的加大而增大;吸力平衡阶段体积应变规律同剪切阶段的变化规律不同。

英文摘要：

Lime-treated expansive clays in semiarid area are in typical unsaturated state. Consequently,to ensure the rational design of foundation treatment,and safe operation,research on shear strength is of great significance.Herein, Based on scanning electron microscope（SEM） technology, digital image processing technology, and unsaturated GDS triaxial stress path system,microstructures,soil-water characteristic curves（SWCC） and strength of improved expansive soil with 7% lime in Xinqiao airport of Hefei were discussed. And strength properties of unsaturated lime-treated expansive clay were also further investigated by means of macro-micro comprehensive methods. It is found that microstructure in lime-treated expansive soil appears obvious harsh granular texture. The diameters were mainly from 0.52 to 7.80 μm,and pore area was less than 4 μm^2. The measured SWCC behaves hysteretic characteristics between drying test and wetting test, and the air-entry suction is bigger than that of undisturbed expansive clay. Under the same amount of cell pressure,the higher suction the larger the peak strength and residual shear strength were. Moreover,for tests with the constant suction,residual shear strength increased with increasing cell pressure. The volume strains in the procedures of suction balance and shearing appeared differently.