Micro screw anchor piles are ideal as the foundation of solar power plants and have been widely used in recent years. In this study, test apparatuses for the uplift loading test, compression test, and lateral loading test of the micro screw anchor pile were designed. Comprehensive field tests (totally 72 piles) for six types of micro screw anchor pile were conducted in clayey, loess, and sandy sites, and some conclusions can be drawn as follows. (1) The typical ranges of bearing capacity in three soil sites with the micro screw anchor pile were obtained under uplift, compressive, and lateral loading conditions; the lateral bearing capacity varied over a small range (8.1 to 11.7 kN) for various site conditions and pile configurations and was much smaller than the uplift and compressive bearing capacities. (2) The screw anchor pile with more helical blades had better performance under uplift, compressive, and lateral loading conditions; increasing the embedded depth of blade substantially enhanced the uplift and compressive bearing capacities but only slightly influenced the lateral bearing capacity. (3) The clayey site had larger uplift and compressive bearing capacities than the loess and sandy sites; the uplift bearing capacity was larger than the compressive bearing capacity in clay but smaller than the compressive bearing capacity in sand. (4) The classic cylindrical shear method was improved by taking into account the shaft resistance above and below the blade(s), which can better predict the uplift and compressive bearing capacities; as for the lateral bearing capacity, a simple but practical prediction method was also proposed. This study will contribute to a better understanding of the failure mechanism and bearing capacity of micro screw anchor piles. The site information and test results are promising to provide data for further analytical and numerical works.

微螺钉锚桩是理想的太阳能发电厂的基础，近年来已被广泛使用。在这项研究中，设计了用于微螺钉锚桩的升力荷载试验，压缩试验和横向荷载试验的试验设备。在黏土，黄土和沙地进行了六种类型的微型螺旋锚桩的综合现场测试（总共72根桩），可以得出以下结论。（1）微型锚杆桩在三个土点的典型承载力范围是在上，压和侧向荷载条件下得出的；在各种工地条件和桩身配置下，侧向承载力在一个很小的范围内（8.1至11.7 kN）变化，并且远小于隆起和压缩承载力。（2）螺旋叶片更多的螺旋锚桩在升力，压缩力和侧向荷载条件下具有更好的性能；增加叶片的嵌入深度可显着增强抗拉力和抗压承载力，但对侧向承载力的影响很小。（3）黏土场地比黄土和沙土场地具有更大的隆起和承压能力；抗拔承载力大于粘土的抗压承载力，但小于砂土的抗压承载力。（4）考虑到叶片上方和下方的轴阻力，改进了经典的圆柱剪切方法，可以更好地预测升力和压缩承载力；对于侧向承载力，还提出了一种简单实用的预测方法。这项研究将有助于更好地理解微型螺旋锚桩的破坏机理和承载力。现场信息和测试结果有望为进一步的分析和数值研究提供数据。