浅埋平板圆锚竖向拉拔极限承载力计算方法

A method for calculating vertical pullout ultimate bearing capacity of shallow circular anchor plate

采用自制可视化试验装置开展了平板圆锚的拉拔模型试验,基于数字照相测量技术对极限拉拔下锚周土体的位移变形场进行了量化分析。在本次试验的埋深比范围内,极限承载力随埋深比增加而非线性增大,但增长速率逐渐减缓;观测到的锚周土体滑动面与地面、锚板所围区域整体呈现出“底大、顶小、径长”的倒喇叭形状;滑动面可用两条直线段来近似描述;极限拉拔力学模型由一个截面直径上小下大的倒圆台和一个等截面圆柱体组成。根据极限平衡条件推导建立了砂土中浅埋平板圆锚竖向拉拔极限承载力的计算方法,该方法对4组试验数据的计算较其他4种方法与试验实测值更为接近,且离散性更小,效果较好。

A self-made visual test device was used to carry out pullout model test of circular anchor plate,and the displacement and deformation fields of the soil around anchor plate were measured and analyzed in the limit state based on the digital photographic measurement technology.Under the test conditions,the ultimate bearing capacity increases nonlinearly with the increase of buried depth ratio,but the growth rate slows down gradually.The observed area surrounded by the soil sliding surface,the ground surface and the anchor plate present an inverted trumpet shape of“large bottom,small top,and long sliding surface”.The sliding surface can be approximated by two straight segments.The ultimate pullout mechanical model consists of an inverted trapezoidal cylinder with a small upper section and a large lower section and an equal-section cylinder.Based on the limit equilibrium conditions,an approach to calculating the ultimate bearing capacity of a shallow circular anchor plate in sand is developed.The calculated results of the four sets of test data by this method are closer to the measured values than by the other four methods,and the dispersion is smaller.