基于DIC技术的砂土中圆形锚板上拔土体变形特性试验研究  

Experimental study on the deformation characteristics of soils around uplift circular plate anchors using digital image correlation technology

作　　者：史旦达 毛逸瑶 杨勇 原媛 郝冬雪[2] SHI Dan-da;MAO Yi-yao;YANG Yong;YUAN Yuan;HAO Dong-xue(College of Ocean Science and Engineering,Shanghai Maritime University,Shanghai 201306,China;School of Civil Engineering and Architecture,Northeast Electric Power University,Jilin,Jilin 132012,China)

机构地区：[1]上海海事大学海洋科学与工程学院,上海201306 [2]东北电力大学建筑工程学院,吉林吉林132012

出　　处：《岩土力学》2020年第10期3201-3213,共13页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.41772273,No.11802172)。

摘　　要：针对福建标准砂,采用非接触式数字图像相关技术(digital image correlation, DIC),通过一系列室内模型试验研究了圆形锚板上拔时锚周土体的变形特性,重点分析了盘径、埋深比和砂土相对密实度的影响。试验结果表明,随着盘径的增加,同一埋深比条件下,上拔力峰值和出现上拔力峰值时的位移水平均明显增大,而上拔承载力系数Nγ则随着盘径的增加而减小,但盘径变化不影响上拔时锚周土体位移影响区的形状,且以上规律不受砂土相对密实度变化的影响。对于密砂,锚周土体位移影响区形状随着埋深比的增加由倒梯形向U字形发展,土体剪切破坏面为沿锚板边缘向外侧斜上方演进的直线型破坏面,且与竖直方向的夹角约为1/4φp(φp为土的峰值摩擦角);随着锚板的上拔,锚板上方土体出现较为明显的体积膨胀。对于松砂,随着埋深比的增加,锚周土体位移影响区形状由延伸至土体表面的矩形向内置于土体的贝壳形发展;浅埋时,土体剪切破坏面沿锚板边缘垂直向土体表面开展;深埋时,土体剪切破坏面沿锚板边缘向内侧斜上方发展,与水平方向的夹角约为45°+1/2φp。无论何种埋深比,锚板正上方均观测到小范围的体积膨胀区,其上为体积收缩区,且随着埋深比的增加体积收缩量逐渐增加。A series of indoor model tests was conducted to study the sand deformation characteristics around uplift circular plate anchors using digital image correlation technology, with emphasis on the effects of plate diameter, embedment ratio and relative density of sand. The experimental results show that when a same embedment ratio is reached, the peak uplift force and the displacement for the appearance of peak uplift force both increase with increasing plate diameter, yet the uplift bearing capacity coefficient decreases as plate diameter increases. The shape of influence zone concerning soil deformation is not affected by the variation of plate diameter, and this regularity is independent of soil density. For the dense sand case, as embedment ratio increases, the shape of influence zone evolves from a reversed trapezoid to a U shape, and a linear shear failure surface can be captured with the inclination angle of 1/4φ_p to the vertical, where φ_p is the peak friction angle of soil. The surrounded soil exhibits a significant volume expansion due to the uplift of plate anchor in dense sand. For the loose sand case, as embedment ratio increases, the shape of influence zone gradually develops from a rectangle extended into soil surface, to a shell shape embedded within the soil. As to a shallow anchor in loose sand, the shear failure surface of soil perpendicularly progresses from the edge of anchor plate to soil surface. When a deep anchor in loose sand is discussed, an inside oblique shear failure surface can be observed and the inclination angle to the horizontal is about 45°+1/2φ_p. Irrespective of the embedment ratio, due to the uplift of plate anchor, a small volume expansion zone is observed above the anchor plate, upon which is a large volume contraction zone with the value of volume contraction increasing with the increase of anchor’s embedment ratio.

关 键 词：数字图像相关技术 圆形锚板 土体变形 上拔承载力系数 

分 类 号：TU473.1[建筑科学—结构工程]