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分散性土耐冲蚀性低、抗渗性能差,在纯水中具有很高的分散性,严重威胁水利工程的安全。在分散性土的鉴别和改性方面已有很多成果,但分散性土动力特性的研究见诸报端的还很少。利用日本诚研社生产的DTC-199型电液伺服加荷往复扭剪三轴仪,对取自宁夏某碾压均质土坝的分散性土的动剪切模量进行了探索。通过改变试样的含水率、干密度和围压等初始条件,研究分散性土在不同试验条件下的动力特性及剪切模量的变化规律,并进行对比分析。得出:分散性土的动剪应力-应变关系符合Hardin-Drnevich双曲线模型;控制初始条件,当其他条件相同时,含水率越低,动剪切模量越大;干密度越大,试样动剪切模量越大;围压越高,其动剪切模量越大;初始剪切模量及最大动剪应力的变化规律与之相似。动剪切模量随动剪切应变的增大普遍呈衰减趋势。
Erosion resistance of disperse soil is low, impermeability is poor, with high dispersion in pure water, a serious threat to the safety of water conservancy projects. There have been many achievements in the identification and modification of dispersive soils, but there are few reports on the dynamics of disperse soils. The dynamic shear modulus of dispersive soils taken from a roller compacted homogeneous earth dam in Ningxia was explored by DTC-199 electro-hydraulic servo-reciprocating torsional shear triaxial apparatus manufactured by Japan Research Institute. By changing the initial conditions such as water content, dry density and confining pressure, the dynamic characteristics and shear modulus of dispersed soil under different experimental conditions were studied and compared. The results show that the dynamic shear stress-strain relationship of dispersive soil conforms to the Hardin-Drnevich hyperbola model. When the initial conditions are the same, the lower the water content is, the greater the dynamic shear modulus is. The higher the confining pressure is, the larger the dynamic shear modulus is. The initial shear modulus and the maximum dynamic shear stress are similar. Dynamic shear modulus increases with the increase of shear stress generally declining trend.