1g model test is carried out to evaluate the ultimate lateral capacity of the spiral model pile. The model piles are scaled down using a proper similarity equation. In order to identify the lateral capacity of the spiral model pile, the conventional pipe and flat bar model piles were conducted as well. To estimate the rigid spiral pile's ultimate lateral capacity in dense sandy soil, a simplified model is proposed based on Winkler's assumption by modifying an ultimate lateral soil resistance.


In the state of the pile foundation's art, novel types of piles have been innovated, viz. helical and spiral shape piles. In a pile foundation engineering and anchoring technology, the spiral pile has been studied and developed in recent years—the spiral pile, which has an advantage, such as less construction work and soil disturbance. Due to wind force, flood and earthquake, the pile foundation suffers lateral force. Considerable lateral forces make an over-deflection to the piles. For recovering deflected pile, a recyclable pile is recommended because of cost-efficiency.

The spiral pile foundations are frequently used in situations where soft soil appears, and minor soil disturbance is needed. Thus, some of the solar panel farms have been using a spiral pile for express construction. The spiral shape pile has low bending stiffness because of the lower cross-section area comparing with the circular shape pile. Therefore, in shearing force, the spiral pile has a relatively higher bending moment along the pile length comparing with the pipe. There is a lack of study focusing on the lateral behavior of spiral piles. However, in the preceding literature, the prediction method of axial bearing capacity of the spiral bolt in the rock by Hirata et al., (2005), and pushing and pull-out performance of spiral pile by Sato et al., (2014), Wang and Tani et al., (2018), were studied. A study on the reinforcement of a single spiral pile using a batter spiral pile was studied by Jugdernamjil and Tani et al., (2020). From the experimental result of Wang and Tani et al., (2018), the rational pitch-width ratio (length of pile pitch divided by the width of pile, p/w) was obtained to be equal to 4.5, which ratio has been used in this research as shown in Fig. 1. A model spiral pile, which is made by twisting a flat bar into a spiral shape. Although, a spiral pile for the field is produced by cast iron because of the availability of fabrication.

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