光伏支架螺旋桩斜向拉拔承载特性试验研究

针对光伏支架螺旋桩斜向荷载作用下承载特性认识不足,在砂土中开展大尺寸单锚片螺旋桩斜向拉拔载荷试验,研究荷载角度、埋深比对承载特性的影响规律,探究锚片表面的土压力强度分布变化规律,分析斜向拉拔承载控制机理。研究表明：1）荷载位移曲线一般表现为硬化型,荷载角度相同时,埋深比越大,拉拔极限荷载与相应位移均越大。埋深比相同时,荷载角度增加,曲线更显陡峭,极限荷载增大,极限位移则减小。2）分解后的荷载-水平位移曲线和荷载-竖向位移曲线特征差异显著,前者曲线完整、非线性发展充分。除竖向拉拔外,其他拉拔角度下竖向极限位移均远小于水平极限位移。3）斜向拉拔承载力T_U(a)与对应埋深比竖向拉拔承载力T_u(90°)之比与荷载角度之间具有很好的线性关系。4）锚片上的土压力强度均受两种锚土相互作用机制共同影响,最大土压力强度系数与埋深比和土体内摩擦角有关,可达被动土压力强度系数的近两倍。5）荷载角度0°,65°],螺旋桩斜向拉拔承载性状由水平方向控制,在65°,90°]则由竖直方向控制。斜向荷载竖向分量可提高螺旋桩水平方向的承载力,但在设计判别时可将其视为安全储备不予考虑。

EXPERIMENT STUDY ON INCLINED PULLOUT BEARING CHARACTERISTIC OF SCREW ANCHOR PILE OF PHOTOVOLTAIC BRACKET

In view of the insufficient understanding of the bearing characteristic of screw anchor pile of photovoltaic bracket under inclined loading, inclined pullout test of large size screw anchor pile with single blade is carried out in sand. The study focuses on the influence regulation of load angle and buried depth ratio on bearing characteristic, the variation of soil pressure distribution on the surface of anchor blade, and the inclined pullout bearing control mechanism. The main conclusions are as follows： （1） The load-displacement curves are generally hardening type, with the same loading angle, the greater the buried depth ratio, the greater the pullout limit load and the corresponding displacement; with the same buried depth ratio, the curve becomes steeper as the loading angle increases, and the ultimate load increases, but the corresponding displacement decreases. （2） There are significant differences between load-horizontal displacement curve and load-vertical displacement curve, the former curve is complete and the nonlinear development is sufficient. Besides the vertical pullout, and the vertical ultimate displacement at other loading angles is far less than the horizontal ultimate displacement. （3） The ratio of inclined pullout capacity T_U(a) to the vertical pullout capacity T_u(90°) with the same burial depth ratio is linear with the loading angle. （4） Soil pressure on anchor blade is influenced by two anchor-soil interaction mechanisms, The maximum soil pressure coefficient is related to the burial depth ratio and the friction angle of soil, the value of which can reach nearly twice of the passive soil pressure coefficient. （5） In the range of 0°,65°], the inclined pullout bearing characteristics of screw anchor pile is controlled by horizontal loading, while in the range of 65°,90°], that is controlled by vertical loading. The vertical component of the inclined loading can improve the horizontal bearing capacity of screw anchor pile, but it can be regarded as a safety reserve in the design judgement.