基质吸力作用下非饱和粉土强度特性研究

发布时间：2018-08-22 15:51

【摘要】：为研究豫东高速公路路基填筑粉土的非饱和力学特性,采用四联非饱和土直剪仪进行控制吸力条件下的强度特性试验,着重分析吸力对非饱和粉土强度的贡献,并对其干密度效应进行了探讨.结果表明,豫东黄河冲积粉土颗粒级配较为集中在0.005~0.075 mm的粉粒组.击实曲线出现了不对称的"双驼峰"现象,但两个干密度峰值相差较大,工程应用中需注意最大干密度的准确获得.非饱和粉土的抗剪强度与固结应力呈线性相关关系.干密度和吸力对粉土的黏聚力c均有影响,但影响规律不同.黏聚力c随吸力的减小呈抛物线变化,在最佳含水率附近黏聚力达到峰值.粉土干密度越大,其黏聚力越大.粉土内摩擦角随吸力增加呈增大趋势,吸力大于100 k Pa后基本趋于稳定,影响幅度在5°以内.基质吸力对抗剪强度的影响呈非线性关系.粉土的内摩擦角φ'与吸力相关,φ~b则受吸力与固结应力共同影响,φ'与φ~b均非常数,在τ_f—(u_a-u_w)—(σ_n-u_a)空间中,摩尔库伦破坏面呈双向弯曲形态.
[Abstract]:In order to study the unsaturated mechanical properties of subgrade filling silt in the east of Henan Province, the strength characteristic tests under the condition of controlled suction were carried out by means of a four-fold direct shear apparatus for unsaturated soil, and the contribution of suction to the strength of unsaturated silt was emphatically analyzed. The dry density effect is also discussed. The results show that the particle gradation of the alluvial silt in the Yellow River in eastern Henan Province is concentrated in the silt group of 0.005 ~ 0.075 mm. The compaction curve appears asymmetric "double hump" phenomenon, but the difference between the two peak values of dry density is great, so attention should be paid to the accurate obtaining of maximum dry density in engineering application. The shear strength of unsaturated silt is linearly correlated with the consolidation stress. Dry density and suction have effects on the cohesion of silt c, but the influence law is different. The cohesive force c changes with the decrease of suction and reaches the peak value near the optimum moisture content. The greater the dry density of silt, the greater the cohesion. The internal friction angle of silt tends to increase with the increase of suction. When the suction is more than 100 KPA, the friction angle tends to be stable, and the influence range is less than 5 掳. The influence of matrix suction on shear strength is nonlinear. The internal friction angle 蠁'is related to suction, and 蠁 b is affected by both suction and consolidation stress. Both 蠁 'and 蠁 B are very numerous. In 蟿 -f- (u_a-u_w)-(蟽 n-ua) space, the molar Coulomb failure surface is biaxially curved.
【作者单位】：中原工学院建筑工程学院;信阳师范学院建筑与土木工程学院;
【基金】：国家自然科学基金项目(51509274) 河南省科技创新人才计划(164200510020) 河南省高等学校重点科研项目计划(15A560013) 中原工学院青年骨干教师资助计划
【分类号】：U416.1

【参考文献】