Session: 10-05-01: Bucket Foundations and Caissons

Submission Number: 154271

The Influence of Seabed Trench on Suction Pile’s Holding Capacity 

Suction piles have been widely used as anchor points for semi-taut and taut mooring systems in deepwater sites for the last decade as this technique has advantages in both technical and economic aspects. Recently, large-size trenches were found in front and near the suction piles in some offshore areas, i.e., West Africa, which may greatly affect the pile’s holding capacity. As this is a relatively new issue, very few studies related to this problem have been carried out. In order to investigate the influence of a trench on a suction pile’s holding capacity, a three-Dimensional Finite Element Analysis (3D FEA) model using Finite Element Code PLAXIS 3D was developed. This paper presents the development of this 3D FEA model to investigate the influence of a trench on a suction pile’s holding capacity in deepwater marine clay. Using this model, a series of FEA runs were carried out. Firstly, the FEA model was used to investigate the remaining capacity of suction piles with trench depth assuming soil behavior was not influenced by the development of a trench. Secondly, the FEA model was used to investigate the remaining capacity of suction piles considering an influence on soil behavior due to the development of a trench. Finally, discussions and recommendations on suction pile’s holding capacity and structural impacts due to a seabed trench were provided to take the trench influence into consideration for suction pile geotechnical designs in similar soil conditions in West Africa offshore. 

Presenting Author: Jianchun Cao Bechtel

Presenting Author Biography: Dr. Jianchun Cao, a Senior Geotechnical Engineering Specialist with Bechtel. Jianchun has more than 30 years experience in both onshore and offshore industries, including design, analysis and construction assistance of shallow foundations as well as deep foundations (driven piles, suction piles. drilled shafts, caissons, compacted and expanded base concrete piles, prefabricated piles, cast-in-place reinforced concrete piles, CFA piles, and vibrato-concrete columns); slope stability analysis using various methods including three-dimensional finite element analysis (FEA) methods; soft soil improvement design (DMM, dynamic compaction, stone column) and construction monitoring; numerical modeling of soil-structure interaction problems using FEA; pile driving analyses using GRLWEAP for excessively long and large diameter piles under various soil conditions; geophysical survey and geotechnical exploration; preparation of specifications for geophysical & geotechnical survey and foundation design for mega projects on behalf of the owners; deep excavation support design and retaining wall design; and performing design review as the owner’s representative.