自钻式原位剪切旁压模型不同固结荷载颗粒流数值试验

发布时间：2018-11-20 20:40

【摘要】：自钻式原位剪切旁压仪具有扰动小,能同时测出不同深度土的变形和强度参数,在精确测定土体参数方面具有广阔的应用前景。然而,目前受分析手段与研究水平的限制,对SBISP多级加载过程中周围土体的变形响应研究较少,而土体变形参数的确定与其变形机制是密切相关的。基于此,应用PFC3D颗粒流程序对不同固结荷载SBISP模型进行了仿真数值试验,试验结果表明:随着剪应力的逐级施加,中间区域颗粒的位移量不断增大,且位移矢量方向性更加显著,在第5级剪应力作用下,影响区域位移矢量形状呈现为倒锥形;而随着上覆固结压力的增大,探头周围试样的受影响范围逐渐变小;在探头作用下球颗粒的运动轨迹呈台阶状,台阶形态随距探杆中心距离增大而趋于平缓,球颗粒的Z向位移量亦随之呈负指数形式衰减;此外,剪应力与探头摩擦系数呈正相关关系,但当摩擦系数达到某一阈值时,剪应力-位移曲线不再变化。其研究成果对于深入开展SBISP试验多级加载过程中影响域内土体变形过程与变形模量之间关系研究具有重要启迪意义。
[Abstract]:The self-drilling in-situ shear pressure-presser has small disturbance and can simultaneously measure the deformation and strength parameters of soil at different depths, so it has a broad application prospect in the accurate measurement of soil parameters. However, limited by the analytical means and the research level, the deformation response of soil around the SBISP multistage loading process is less studied, and the determination of soil deformation parameters is closely related to its deformation mechanism. Based on this, the PFC3D particle flow program is used to simulate the SBISP model of different consolidation loads. The experimental results show that the displacement of particles in the intermediate region increases with the application of shear stress step by step. The direction of displacement vector is more obvious, and the shape of displacement vector is inverted cone under the action of the fifth order shear stress. However, with the increase of the overburden consolidation pressure, the influence range of the specimen around the probe becomes smaller. Under the action of the probe, the trajectory of the ball particle is like a step, the shape of the step tends to be gentle with the increase of the distance from the center of the probe, and the Z direction displacement of the ball particle attenuates in the form of negative exponent. In addition, there is a positive correlation between the shear stress and the friction coefficient of the probe, but when the friction coefficient reaches a certain threshold, the shear stress-displacement curve does not change. The research results are of great significance for further research on the relationship between soil deformation process and deformation modulus in the multi-stage loading process of SBISP test.
【作者单位】：中国地质大学工程学院;西安科技大学建筑与土木工程学院;武汉中交岩土工程有限责任公司;
【基金】：国家自然科学基金资助项目(No.41072218)
【分类号】：TU413

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