高竖向应力作用下海砂直接剪切特性研究

随着近海工程项目的日益增多,海砂可作为经济性建筑材料,但关于高应力作用下海砂的剪切特性研究未见相关文献。通过研究高竖向应力作用下中等粒径海砂的直剪特性,探究了剪切速率对强度指标的影响,得出以下主要结论:(1)随着竖向应力的增大,海砂应力-位移曲线的软化特性越来越突出。(2)海砂达到峰值应力时的位移大致呈现随竖向应力的增大而逐渐增大的趋势。(3)剪切过程中,竖向位移逐渐减小并趋于稳定,表现出剪胀特性。(4)竖向位移-剪切位移关系曲线在初始过程呈现出轻微的剪缩过程,表现为一个较长的稳定阶段,主要是与材料选择与高竖向应力有关。(5)剪切速率对高竖向应力作用下摩尔-库伦曲线的斜率有一定影响,近似可认为随剪切速率的增大,表现为内摩擦的降低。研究成果对近海工程项目建设有一定的参考价值。

Direct Shear Characteristics of Marine Sand under Higher Vertical Stresses

With increasing offshore engineering projects, marine sand can be used as an economic building material, but there is no relevant literature on the shear characteristics of marine sand under higher stresses. In this paper, the direct shear characteristics of medium-sized marine sand under higher vertical stresses are studied, and the influence of shear rate on the strength index is explored. With the increase of vertical stress, the softening characteristics of the stress-displacement curve of marine sand become more and more prominent. The displacement when the marine sand reaches the peak stress tends to increase with the increase of vertical stress. During the shear process, the vertical displacement first decreases gradually and then tends to become stable, showing shear expansion characteristics. The relationship curve of vertical displacement and shear displacement presents a slight shear contraction process in the initial process, representing a long-term stable period mainly due to material selection and high vertical stress. The shear rate has a certain impact on the slope of the Mohr-Coulomb curve under the action of high vertical stress, which can be roughly understood as the increase of shear rate is represented as the decrease of internal friction. Our study results have some values for offshore engineering projects.