沉积方向对饱和密砂力学特性的影响

Influence of Sedimentary Direction on Mechanical Characteristic of Saturated Dense Sand

沉积方向对土体强度的影响对于研究初始各向异性而言具有重要意义。基于砂土颗粒的毛细效应提出一种试样制备方法,制备若干组具有不同沉积方向的密砂试样。通过系列三轴固结排水剪切试验研究沉积方向对强度、体变的影响,并拟合得到沉积方向和峰值强度的关系公式。研究表明:沉积方向夹角在0°~90°范围内对峰值强度和体变的影响比较显著,当沉积方向夹角与试样破坏面方向(45°+φ/2)接近时,剪切带形成得更早,试样更容易达到破坏,所对应的峰值强度更低,达到峰值和残余状态更早。依据试验结果拟合得到沉积方向夹角和峰值强度的关系公式,公式预测结果与试验结果吻合度在不同围压条件下均较高。研究结果为研究砂土的初始各向异性力学特性提供了有益的方法。

The influence of sedimentary direction on the strength and volumetric change of dense sand was examined via series of triaxial conslidated drained shear test.Dense sand specimens with different sedimentary directions were prepared based on the capillary effect of sand.Test results revealed that sedimentary direction had obvious influence on the ultimate peak strength and volumetric deformation of sand when the direction changed between 0°~90°.When the sedimentary direction was close to the failure plane direction which is suggested as(45°+φ/2),the shear band of sample developed earlier,leading to easier failure with lower peak strength and earlier residual stage.Furthermore,a fitting formula reflecting the relation between sedimentary direction and peak strength is put forward.The formula-predicted result well coincided with test result under different confining pressures.Studying the influence of sedimentary direction on strength is of importance to the research of initial anisotropy of sand.