Vertical and Lateral Bearing Capacity of FRP Composite Sheet Piles in Soft Soil

Zhe Wang,Wangjing Yao,Sifa Xu,Zhouxiang Ding,Kaiwen Weng,Shuwei Wu

doi:10.1155/2020/8957893

Abstract

Fiber-reinforced polymer (FRP) composite sheet piles are usually favored for slope and river-retaining structures due to their construction and environmental efficiency. Their applications, however, have been hindered by the lack of understanding of the bearing capacity. This paper studies the vertical and lateral bearing capacity of FRP composite sheet piles through three full-scale tests conducted in Haiyan, a soft soil site in the Yangtze River Delta of China. In the three tests, we measured the vertical bearing capacity of the FRP composite sheet piles, the bearing capacity of the composite foundation, and the lateral capacity of the FRP composite sheet piles, respectively. The test results show that the Q-S (load on the top of the pile versus settlement) curve of the FRP composite sheet piles exhibits a steep fall while that of the composite foundation is relatively flat. Moreover, the ultimate bearing capacity of the FRP composite sheet piles is measured to reach 23.8 kN while that of the composite foundation increases by 47.1 %, reaching 35.0 kN. It shows that the FRP composite sheet piles under the composite foundation have a favorable bearing performance. Finally, the final horizontal displacement of the FRP composite sheet pile in the reinforced area with anchoring the sheet pile is smaller than the final horizontal displacement in the nonreinforced area, indicating that the horizontal bearing capacity can be significantly improved by anchoring the sheet pile.

Highlights

Steel sheet pile cofferdams have been widely used for river and coastal revetments, piers, and other support structures built in the water because of their convenience of installment, cost efficiency, and reusability
According to the Technical Code for Testing of Building Foundation Piles [32] and the Technical Specification for Composite Foundations [33], the ultimate bearing capacity in the pile load test is referred to as the prior load level preceding the subsequent load level under which the pile top settlement exceeds twice that of the prior load level and the relative stability standard fails to be met in 24 h. erefore, the pile foundation is considered to have failed at the application stage of the load 210 kN, namely, the composite foundation has correspondingly reached its ultimate bearing capacity
In terms of incremental analysis, points b, c, and d in the A1 area are featured by the lateral displacement increments in different magnitudes: (1) relatively small for the Group 0 (G0)-Group 1 (G1) and Group 4 (G4)-Group 6 (G6) stages; (2) intermediate for the G1-Group 2 (G2) and Group 3 (G3)-G4 stages; (3) relatively large during the G2-G3 stages. e largest lateral displacement increments account for 51.8, 51.4, and 54.0% of the total lateral displacement, respectively

Summary

Introduction

Steel sheet pile cofferdams have been widely used for river and coastal revetments, piers, and other support structures built in the water because of their convenience of installment, cost efficiency, and reusability. Research has been conducted into the applications of steel sheet piles [1,2,3,4]. E problem of corrosion was found in those steel sheet piles exposed to the marine environment [5,6,7]. Solvent or heavy metal coatings were applied to those steel piles, which have serious environmental consequences [9]. E advantages of FRP composite sheet piles over steel sheet piles lie largely in their lightness, high specific strength, high durability, corrosion resistance, chemical resistance, and low maintenance [10,11,12]. FRP composite piles may be employed to replace traditional steel piles under harsh environmental conditions [13]. FRP composite sheet piles tend to be more affordable as they have been more widely adopted in construction [17]

Methods

Results

Discussion

Conclusion