Practical applications of DDA to disaster prevention

Some of practical applications of DDA to disaster prevention in Kyushu University are introduced. The first application is to analyze stability of breakwater by considering tsunami induced see page. A local piping mode and global failure mode are clarified by DDA simulations. The second application is to analyze stability and simulate cave-in phenomenon for sand beach. An approach of using DDA to continuous material like sand ground is proposed by generating proper artificial mesh. The bearing capacity and arch function are clarified for the sand ground with a cave. The cave-in phenomenon is reshown by DDA simulations. The third application is to clarify the mechanism of extreme earthquake wave based on so-called trampoline effect and ping-pong model. The extreme waveform with a PGA of more than 4000 gal recorded in Japan is reshown by DDA simulation. These applications will play an important role in disaster prevention in future.