الفهرس | Only 14 pages are availabe for public view |
Abstract Titls thesis studies the stability of sand, gravel, and rock beaches under wave forces. The stability of these beches is affected by their slope angle, particle grain size diameter, wave height, wave period, approach angle, and closure water depth. Wave attack on beaches affects their stability depending on the particle grain size diameter. For small particle grain sizes the wave attack affects the profile development and reshape it into different shapes. For particles of large grain size diameters, the wave attack leads to local instability of individual particles. The stability of beaches is investigated using a computer program, which is developed to check whether a beach is stable or not. In the present study, for sand and gravel beaches, there are two pivot points on the profile; the first point, is located at the intersection of the profile with the still water level, the second point is found at the toe of the profile. These two pivot points maintain the assumed initial slope of the deformed profile, from which the eroded and accreted volumes between this initial slope and the profile may be computed, and consequently the stability of sand or gravel beaches may be predicted depending on the relative values of the net volume to the eroded volume. For rock beaches, the stability depends on the failure mechanisms of each individual particle on the profile. These mechanisms of failure may be categorized as: sliding, rolling, and lifting. The stability of rock beaches is presented in a design chart collecting all the affecting variables. from this chart the stability of rock beaches can be increased by decreasing the slope or covering the beach by rocks with larger grain size diameter. A solved example is given for demonstration the uses of the derived model for checking the stability of a beach and its protection in case of the unstability. |