Development and Application of Static Load Test System for Pile Foundation Based on Steel Screw Anchor Piles

A new type of static load test system and test method based on steel screw anchor pile is proposed. Through field uplift tests of single pile and pile group, the influence of soil properties, pile length and other factors on the uplift bearing capacity of steel screw pile is analyzed. The influence range of steel screw pile on the displacement of adjacent soil and pile foundation are revealed. The calculation method of ultimate uplift bearing capacity of single steel screw anchor pile is established. The reliability of the test method is verified by practical cases. The test results show that the uplift bearing capacity of steel screw pile is higher than that of straight rod pile. According to the properties and compactness of the soil, the coefficient of uplift side resistance improvement of steel screw piles can be taken as 1.2 - 1.6. The construction of steel screw pile is convenient and can be reused, without special treatment of the test site. The test method can save up to 70% of the cost compared with traditional surcharge test method, and greatly improve the safety of large-tonnage static load test.