The aim of this study is to design economically foundations which are subjected to large lateral forces such as unsymmetrical earth pressure or seismic inertia force of superstructure by using grid form soil improvement wall used as liquefaction prevention of soft ground. The proposed way is to add dents and bumps to the head of the soil improvement and unite concrete foundation with it for lateral force transmitting. Lateral resistance of the joint is studied theoretically and experimentally. The results show the performance of the joint is more than 1.5 times larger than the no dent and bump joint under same contact pressure and the proposed calculation formula is valid.

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It is introduced that the construction process of west artificial island of Hong Kong-Zhuhai-Macao Bridge. The emphasis is the settlement of foundation and the deformation of island wall which are calculated by finite difference method (FDM) during construction. By analysis, consolidation settlement of soft clay foundation and steel cylinders deformation under every construction procedure are known. And key procedures are discovered for guiding design and construction. The results show that two construction procedures backfilling sand in the island and flinging stone outside the island to be slope are key procedures, because they have greater influence on steel cylinders and foundation of island. Foundation settlement speed in the construction period is far greater than the specification requirements, while foundation crack and other accidents are not available. The reason is steel cylinders restricting lateral deformation of soft clay foundation. Therefore, the foundation settlement control standards in such artificial island should break through the requirements of specification. Meanwhile, it is known that the maximum settlement of soft clay foundation of artificial island is 2.92m. Residual settlement is 13cm. Maximum vertical displacement of the steel cylinder top is 28.5cm, and lateral displacement is 8cm.

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In the 2011 off the Pacific coast of Tohoku Earthquake, especially coastal areas of the Pacific Ocean suffered extensive damage by tsunami. Then, there were needs to develop reinforcement methods for existing breakwaters against tsunami force. The authors proposed a method to reinforce a breakwater against tsunami with a steel wall behind the breakwater. This report presents the experimental results of the breakwater reinforcing method. In the proposed method, steel piles are inserted behind the breakwater and rubbles are filled between the caisson and the piles. The model caisson failed in sliding mode without this improvement method. When it was reinforced with steel walls and filling, the horizontal resistance of the model caisson improved effectively. The failure mode of the caisson changed from sliding mode to ground failure mode. By analyzing the bending moment of the steel wall, the stress distribution in the wall from the caisson via filling and the ground was obtained and failure surface of the ground can be estimated.

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This paper deals with development of an effective reinforcement technology for breakwater foundation which provides resiliency to breakwater against earthquake. The technique involves use of steel sheet piles and gabion type mound (gravel wrapped up in steel wired mesh) in the foundation of breakwater as a reinforcing measure, which is effective in preventing subsidence and horizontal displacement of breakwater. A series of shaking table test were performed to evaluate the effectiveness of the developed technique under earthquake loadings. The results of this study reveal the advantages of resilient breakwater in reducing the damage to breakwater foundation brought by destructive earthquake.

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In finite element modelling of laterally loaded pile or pile subjected to soil movement, normal stiffness (Kn) of pile-soil interface is required. However, the correlation of normal stiffness to soil stiffness is not widely available. This paper shows the results of the investigation of the normal stiffness by simulating the renowned laterally loaded pile test in Houston (in clay medium) and Arkansas (in sand medium). Series of parametric studies using 3D finite element program were carried by varying the ratio of normal stiffness to soil Young's modulus at reference level. By matching pile lateral deflection and bending moment of the pile. This study suggested that a ratio of Kn/Eoed 10 ~ 100 is acceptable for pile in clay domain while a ratio of Kn/Eoed 1 ~ 10 is acceptable for pile in sand domain. The study also found that Mohr Coulomb model fails to model the response of laterally loaded pile. By using an appropriate normal stiffness, the ultimate lateral load of the pile can be predicted by using 3D finite element program.

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Seawalls are constructed to defend the shorelines from wave attack. Depending on the ratio of maximum design wave height to the depth of still water at the wall the wave forces acting on the seawall are classified as non-breaking wave force, breaking wave force and broken wave force. Seawall will be subjected to non-breaking wave force, when the depth of water at the wall is greater than 1.5 times the maximum design wave height. In the present analysis a vertical face rigid waterfront retaining wall supporting submerged backfill, and is subjected to non-breaking wave force is considered. Stability analysis has been carried out by considering two cases viz., when wave trough is at the wall, which causes active earth pressure condition, and when wave crest is at the wall, which leads to passive earth pressure condition and the stability is reported in terms of factor of safety against sliding and overturning modes of failures. Sensitivity analysis has been conducted for investigating the effects of different parameters, such as, relative wave height, soil and wall friction angles and height of water on landward side. It is observed that factor of safety against overturning mode of failure decreases by 80% when the ratio of non-breaking wave height to water depth on seaward side changed from 0 to 0.6. The proposed closed form solutions and design charts provide a better guideline for design of seawall subjected to non-breaking waves against sliding and overturning modes of failures.

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