Lateral behavior of soldier pile-type breakwater in soft ground

Abstract

For most of small scale harbors and fishery ports in Korea, conventional construction methods of breakwater would have low economical efficiency due to the soft ground conditions of loose sandy soils or clayey soils in spite of low design wave. Therefore, it is necessary to develop an economical breakwater applicable to the circumstances with relatively low design wave and soft ground condition. In this study, a soldier pile type breakwater, which is the economical and ecological structure and can be easily constructed on soft ground without any need of ground improvement, was newly introduced. The proposed breakwater can be classified into two types, e.g., a typical flat type breakwater and a saw type breakwater. The former can be utilized to soft ground condition more effectively with an aid of the enforcement methods such as raker or anchor cable. On the other hand, the latter has a structural characteristic of increasing the resistance against bending moment because the soldier piles are connected in zigzag manner. Several model tests were performed to investigate the effects of various factors such as embedded depth of the pile, reinforcement methods (raker, anchor cable), and soldier pile connection types (flat type vs. saw type) on the lateral behavior of the proposed breakwaters, which were installed into loose sandy soils with relative density of 11-38%. Furthermore, parametric studies on clayey soils were also carried out by use of finite element program ABAQUS, which deploys Von-Mises failure criteria for soils. The results revealed that the lateral resistance increases to constant values as the embedded depth increases and even for a very soft ground the lateral resistance can be assured by adopting the reinforcement techniques such as raker and anchor. And, it was also verified that the saw type breakwater shows a better geotechnical performance than the flat type breakwater if no additional reinforcement methods are utilized. Copyright © 2007 by The International Society of Offshore and Polar Engineers(ISOPE).