Design of eco blocks for protection of submerged pipeline
In order to protect coastal facilities mainly from wave and current actions, the self-locking eco blocks constituting elements of protecting shore structures against scouring were designed. These blocks are adapted to the sloping bottom, coastal dunes, and submerged coastal pipelines, counteracting the destructive and erosive impulse action. A series of laboratory experiments has been conducted to investigate the reflection of water waves over and against a train of protruded or submerged shore structures and compare the reflecting capabilities of incident waves including wave forces. In this study the hydraulic model experiment was conducted to identify the performance of newly designed water affinity eco blocks to keep the coast slope and bottom mound from scouring by reduction of the wave reflection and to convince stability of the block placement. Revised design of each block element was also tested for field conditions. From the result of experiments, the field applicability of the developed blocks and placement was discussed afterward.
CONTROL OF CROSS-SHORE SEDIMENT TRANSPORT BY A DISTORTED RIPPLE MAT
A method to control cross-shore sediment transport by a distorted ripple mat which is the artificial ripples of distorted cross section has been studied through hydraulic experiments and numerical simulation. First of all,the relative importance of factors affecting cross-shore sediment transport on fixed bed ripples and the condition on which sediment is definitely transported onshoreward are obtained. Based on this condition,experiments with movable bed are carried out to see how efficiently the distorted ripple mat can be utilized in stabilizing natural/artificial beaches. Furthermore,a. numerical model of beach profile change in which effects of ripple distortion are considered has been developed and beach stabilizing effects of the mat are also reproduced numerically.
Evaluation and Control of Collapsible Soils
Some compacted soils wetted under certain conditions of compaction and loading may exhibit additional settlement (collapse). To investigate the effect of the soil type, compaction water content, initial dry unit weight and applied pressure at wetting on collapse potential, 138 single‐oedometer tests were conducted on eight different soils. The results indicate that well‐graded soils tend to collapse more than poorly graded ones under similar conditions. Furthermore, collapse potential decreases with an increase in (1) The difference between the sand and clay percentages; (2) compaction water content; and (3) initial dry unit weight, while it increases with pressure at wetting. A multiple regression analysis was performed on the laboratory results to provide a collapse‐predictive model that was substantiated by data reported by several researchers. A chart is presented to estimate (1) The collapse potential of soils under various conditions; and (2) the critical water content beyond which no collapse is ex...