剪切速率对沼泽草炭土抗剪强度的影响研究

Study of influence from shear rate on shear strength of swamp tukfy soil

剪切速率对岩土体力学特性有重要影响,为揭示剪切速率对沼泽草炭土抗剪强度的影响规律,进行原状沼泽草炭土的分解度试验、扫描电镜试验以及不同固结围压下4种剪切速率(0.006%·min-1、0.008%·min-1、0.010%·min-1和0.012%·min-1)的固结排水三轴压缩试验。试验结果表明:当固结应力较小时,轴向应变较小时(<4%),剪切速率对应力-应变关系曲线影响较小;同一固结状态下,随着剪切速率的增加,相同轴向应变(>4%)的主应力差逐渐增大;轴向应变达到15%时,0.012%·min-1的主应力差比0.010%·min-1约大25%,0.010%·min-1的主应力差比0.008%·min-1约大20%;剪切速率对草炭土三轴固结排水强度影响较大,剪切速率增加,内摩擦角增大,黏聚力变化不大,抗剪强度提高。研究成果为沼泽草炭土地区铁路与公路线路工程的路堤填筑施工提供试验参考。

The shear rate has an important influence on the mechanical properties of rock and soil.In order to reveal the influence of shear rate on the shear strength of the swamp tukfy soil,the decomposition degree experiment and scanning electron microscopic experiment(SEM)as well as the triaxial compression experiments with four kinds of shear rates(0.006%·min-1,0.008%·min-1,0.010%·min-1 and 0.012%·min-1)under different consolidation confining pressures were carried out on the undisturbed swamp tukfy soil.The experimental results show that when the consolidation stress is small with small axial strain(<4%),the influence of shear rate on the stress-strain relationship curve is less.Under the same consolidation state,the principal stress difference of the same axial strain(<4%)is to be gradually increased along with the increase of shear rate.When the axial strain reaches 15%,the principal stress difference of 0.012%·min-1 is about 25%larger than that of 0.010%·min-1,while the principal stress difference of 0.010%·min-1 is about 20%larger than that of 0.008%·min-1.The influence of shear rate on the triaxial drained consolidation strength of the swamp tukfy soil is larger,thus the internal friction angle is to be increased with little change of cohesion and the increase of shear strength along with the increase of the shear rate.The study result can provide the experimental reference for the construction of the embankment filling for the railway and highway line engineering project within the area of swamp tukfy soil.