颗粒级配对粗粒土强度和变形特性的影响

The Influence of Particle Gradation on Strength and Deformation Characteristics of Coarse-grained Soil

对掺加不同比例碎石的粗粒土进行了大型三轴试验,得到了颗粒级配对粗粒土强度和变形特性的影响规律.在素土中掺加不同比例的碎石可以明显改善土体的颗粒级配组成;素土和改良土的应力应变关系表现为加工硬化型,随着粗粒含量的增加,同一轴向应变对应的偏应力增大,围压增加也会导致偏应力增大;偏应力与轴向应变表现为明显的双曲线关系,初始切线模量和极限应力随着P5含量和围压σ3的增加而增大;P5含量的增加有助于提高土样内摩擦角φ和黏聚力C,而含泥量增加会导致内摩擦角φ和黏聚力C减小;低围压时粗粒含量较多的土样表现出明显的剪胀,较高围压时产生的体积应变较大;径向应变ε3与轴向应变ε1表现为明显的抛物线关系,通过改进的邓肯-张的E-ν模型得到初始泊松比μi受围压和颗粒级配的双重影响.

Large triaxial tests of coarse grained soil mixed with different proportions of gravel have been performed, which obtains the effect law of particle gradation on strength and deformation characteristics of coarse grained soil. Mixing different proportions of gravel into the natural soil can significantly improve the particle size distribution. The stress-strain relationship of natural soil and improved soil work is hardening. With the increase in coarse content, the same axial strain corresponds to the deviator stress increases. The increase of confining pressure will increases the deviator stress. Deviatoric stress and axial strain show a hyperbolic relationship. Initial tangent modulus and ultimate stress increase as the increase of P5 content and confining pressure. The increase of P~ content helps to improve the internal friction angle and cohesion.The increase of clay content decreases the angle of internal friction and cohesion. As low confining pres- sure, the soil samples with more coarse content show significant dilatancy; as high confining pressure, the volumetric strain increases; the relationship of radial strain with the axial strain performs parabolic. By im- proving Duncan-Chang E-v model, the initial Poisson＇s ratio is affected by the confining pressure and the particle size distribution.