基于三轴UU试验的土体含水率对根土复合体强度特性的影响

Effect of Soil Moisture Content on Strength Characteristics of Root-soil Complex Based on Triaxial UU Test

为研究自然边坡其强度特性随含水率的变化规律。通过设计不同体积含水率(20%,27%,35%,40%,45%)和2种含根量(RAR=0.1%,0.3%)的重塑土进行不固结不排水三轴试验,以研究含水率对土体破坏方式、抗剪强度和初始切线模量的影响。结果表明:(1)试样破坏模式多为剪切变形和剪胀变形,在含水率为20%,27%时,出现明显剪切贯穿面破裂带,其余含水率下表现为剪胀变形;(2)含水率对根土复合体抗剪强度主要体现在黏聚力上,含水率从20%升至45%时,2种含根量的根土复合体黏聚力分别降低67%,72%;含水率低于35%时,可用对数关系表示,随含水率升高,黏聚力明显降低;含水率达到35%以上时,可用线性关系表示,黏聚力下降速度减缓;含根量增加,抗剪强度提高;(3)不同含根量和围压下根土复合体初始切线模量与含水率关系可以用线性关系拟合,含水率从20%升至45%时,2种含根量的根土复合体初始切线模量平均分别降低43%和47%。综合考虑土体弹塑性和植物因素对土体位移或变形的影响,可提高边坡稳定性计算精度。研究结果可为植物边坡以及水土保持植被建设治理提供科学参考,丰富根系固土领域的科学理论。

In order to study the variation of strength characteristics with moisture content of natural slopes.The influence of moisture content on soil failure,shear strength and initial tangent modulus was carried out by designing reconstituted soil with different volume moisture content(20%,27%,35%,40%,45%)and two root content(RAR=0.1%,0.3%).The results showed that:(1)The specimen rupture mode was mostly shear deformation and shear expansion deformation,and when the moisture content was 20%and 27%,the obvious shear penetration surface fracture zone appeared,and the rest of the moisture content was shear deformation.(2)The effect of moisture content on the shear strength of the root soil complex was mainly reflected in the cohesion,and when the moisture content increased from 20%to 45%,the cohesion of the two kinds of root-soil complex decreased by 67%and 72%;when the moisture content was lower than 35%,it could be expressed by logarithmic relationship,and the cohesion decreased significantly with the increase of moisture content;when the moisture content reached more than 35%,it could be expressed by linear relationship,and the decline rate of cohesion slowed down;the shear strength increased with the increase of root content.(3)The relationship between the initial tangential modulus and the moisture content of the root-soil complex under different root content and confining pressure could be fitted by linear relationship,and when the moisture content increased from 20%to 45%,the initial tangential modulus of the two root-soil complex with root content decreased by 43%and 47%on average.Comprehensively considering the influence of elastic-plasticity and plant factors on soil displacement or deformation,the accuracy of slope stability calculation could be improved.The research results can provide scientific reference for the management of plant slope and soil and water conservation vegetation construction,and enrich the scientific theory in the field of root soil consolidation.