自钻式原位剪切旁压模型不同固结荷载颗粒流数值试验  

PFC^(3D) numerical experiments of self-boring in-situ shear pressuremeter model test under different consolidation pressures

作　　者：张亚飞[1] 徐光黎[1] 申艳军[2] 胡焕忠 

机构地区：[1]中国地质大学工程学院,武汉430074 [2]西安科技大学建筑与土木工程学院,西安710054 [3]武汉中交岩土工程有限责任公司,武汉430052

出　　处：《岩土力学》2014年第2期591-600,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.41072218)

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。The self-boring in-situ shear pressuremeter （SBISP） has little disturbance to the surrounding soil. It can simultaneously determine the deformation and strength parameter of easily disturbed soil at depth and has an extensive application prospect in the determination of soil parameters accurately. However, the deformation response of surrounding soil under multilevel loading process in SBISP test has seldom been studied up to present because of the limitations of the analytical tools and research level. At the same time, the determination of the deformation parameter of the soil is closely related to its deformation mechanism. Based on this, the SBISP model test under different consolidation pressures is simulated by particle flow code in three dimensions （PFC3D）. The results of numerical experiments show that the displacements of particles in central area increases with the shear stress imposed stepwise;and the direction of displacement vector shows a clearly preferred direction. The shape of displacement vectors in influence area is a reverse cone under the fifth grade shear stress. Additionally, with the increase of the consolidation pressure, the influence area of the numerical sample diminishes gradually. The motion trails of particles are step-like lines; the steps are becoming gentler as the distances from particle to the probe rob center increasing; and the vertical displacements of particles descend in a negative exponential form. The magnitude of shear stress depends on the frictional coefficient of the probe;the shear stress-shear displacement curve is no longer changes when it reaches a certain value. This study is of great enlightened significance in the further research of the relation between deformation process and deformation modulus of soil under multilevel loading process in the SBISP test, which lies in the influence area.

关 键 词：自钻式原位剪切旁压试验 颗粒流 变形响应 不同固结荷载 运动轨迹 

分 类 号：TU413[建筑科学—岩土工程]