西北地区光伏支架微型抗拔类基础优化设计及试验研究

为了解决西北地区光伏支架基础的设计和应用问题，在传统抗拔类基础之上提出了微型锚杆复合桩。通过在西北某光伏电站砂砾石场地的现场足尺试验，由竖向位移观察装置及埋设在不同深度处的应力计对加载过程中各试桩的位移变形和轴力变化情况进行了全时动态监测，对比分析了传统抗拔基础和微型锚杆复合桩的承载特性及相关工程应用问题。结果表明:传统抗拔类基础的荷载 位移曲线形态因桩型不同而异，微型锚杆复合桩呈现缓变型；传统抗拔类基础的极限承载力普遍低于15 kN，而微型锚杆复合桩普遍高于60 kN，承载能力大幅度提高，但微型锚杆复合桩承载力随桩长提高方面存在临界长度（4 m）；微型锚杆复合桩抗拔承载特性优化参数分别从承载力、位移变形及复合优化效果3个方面定量表征了相近桩基尺寸下微型锚杆复合桩的优越抗拔工作性能；建议在西北砂砾石场地适度推广应用微型锚杆复合桩作为光伏支架抗拔基础，其中桩长设计可控制在4 m以内。

Optimal Design and Experimental Research of Photovoltaic Support Micro Anti Pull-out Foundation in Northwest China

In order to solve the design and application of photovoltaic support foundation in northwest China, the composite pile with micro anchor composite pile was put forward on the basis of traditional anti pull out foundation. The field full scale test of sand gravel site was carried out in a photovoltaic power station in northwest China, the displacement and axial force changes of the test piles during the loading process were monitored dynamically at full time by the vertical displacement observation device and the stress gauges embedded in different depths. The bearing capacity and engineering application of the traditional anti pull out foundation and micro anchor composite piles were compared and analyzed. The results show that the load displacement curves of the traditional anti pull out foundation vary with the pile type, and the curves of micro anchor composite pile exhibit slow change type. The ultimate bearing capacity of the traditional anti pull out foundation is generally lower than 15 kN, while that of the micro anchor composite pile is generally higher than 60 kN. The bearing capacity of micro anchor composite pile increases greatly, but it has critical length (4 m) with the increase of pile length. The optimal parameters of anti pull out bearing characteristic of micro anchor composite pile reflect excellent working performance with similar pile size in three aspects quantitatively, including the bearing capacity, displacement and composite optimal effect. It is suggested that the micro anchor composite pile can be applied as the pull out foundation of the photovoltaic support in the northwest sand gravel site, and the design of pile length can be controlled within 4 m.