不同胶结宽度粒间胶结特性试验研究

Experimental study of mechanical behaviors of bonded granules with different bond widths

胶结砂土中水泥含量、能源土中水合物的含量会导致其宏观力学特性的差异,从微观层面可以解释为颗粒之间胶结物含量的不同所导致的粒间力学性质的差异所致。为研究不同胶结物含量的胶结颗粒的力学特性,进行了不同胶结宽度的粒间胶结试验,试验结果表明:(1)峰值压缩荷载随胶结宽度的减小呈非线性变化,宽高比对峰值荷载有明显影响;(2)峰值拉伸荷载随胶结宽度减小而线性减小,宽高比对其影响不大;(3)峰值剪切荷载和峰值扭矩由两部分组成,即胶结部分和摩擦部分。且其变化趋势相似,随着法向荷载的增大,峰值荷载先随之增大,在达到临界应力比后,峰值荷载开始减小,当应力比达到1,即胶结破坏时,胶结部分不再发挥作用,此时粒间荷载由摩擦部分提供;(4)在压-剪-扭试验中,不同初始偏心距情况下得到的峰值荷载在剪力-扭矩平面内呈椭圆状。

The content of cementation in structured soil and hydrate in the methane hydrate-bearing sediments can influence the mechanical behaviors of the materials. Microscopically, this can be attributed to the different contents of cementation between the particles in the materials of concern. To investigate the mechanical properties of bonded particles with different contents of cementation, a series of experiments on bonded granules with different bond widths is carried out. The results show that：（1） The peak compression force decreases nonlinearly with the bond width, and is significantly affected by the aspect ratio;（2） The peak tension force decreases nearly linearly with the bond width, and trivially affected by aspect ratio;（3） The peak shear force and torsion are composed of two parts, namely bond part and frictional part, which vary in a similar way. The peak force increases first with the normal force; once after a critical stress ratio, it starts to decrease, and when the stress ratio equals 1.0, i.e., the bond material fails, the cementation no longer contributes to the peak force and the friction becomes dominant;（4） In the normal-shear-torsion tests under different bias-centroid distances, the peak force on the shear-torsion space has a ellipsoid shape.