Abstract
The Maebashi mudflow deposit ground saturated with ground water consists of the weakly combined volcanic ash sand. The strength of this volcanic ash sand is small as the N-value is between 3-11, which entails the possibility of liquefaction during large earthquakes. Cyclic undrained triaxial tests have been done using undisturbed samples obtained from the sand deposit. The liquefaction characteristics of the sand were investigated. From the results of the cyclic undrained triaxial tests, the liquefaction strength ratio RL was found to be 0.43-0.69, which means that the calculated resistance ratios for the liquefaction became 1.0 or more. This result contradicts with the information from N-value stated above, the reason of which is considered in this study. Furthermore, the seismic effects on infrastructures constructed on the Maebashi mudflow deposit ground are investigated and considerable reduction of their construction costs by evaluating RL correctly is suggested.
