Numerical Analysis Of The Properties Of Large Diameter Cast-In-Situ Tubular Piles Under Horizontal Load

Seawall constructed with large diameter cast-in-situ tubular piles is a new type of seawall. Compared with traditional seawalls, it has more advantages in terms of fast-construction, material-saving and high bearing capacity. But nowadays it is not widely used in ocean engineering because few researches have been done on its working behavior.By using stiffhess equivalent method, this structure is simplified into plain strain problem. Horizontal load is the main load acting on the structure. Hence through numerical analysis, the horizontal properties of this kind of seawall are investigated. Different effects on its behavior are studied, such as soil properties, pile space, piles stiffness, beam stiffness, penetration depth, the location of connecting beam and rubble reinforcement. Useful conclusions are drawn as following. The best penetration depth is 2d (d is the outer diameter of tubular pile) and the suitable pile space is 4d. It is rather recommended to increase the stiffness of connecting beam than the pile stiffness itself. The location of connecting beam is suggested to be a little farther from the top of the piles. It is better to reinforce the soft clay in the seafloor and dumped rockfill is tested to be a good treatment. The range of the treatment is a key parameter and suggested to be 3d.Then different cross sections of the traditional seawalls and its application are introduced. Security, economy and environmental protection are three key issues in the design. The principles and procedures of seawall designing are also put forward. Two cases studies demonstrate that despite of many advantages, this structure can not be used in all situations because of the limited length and stability.