Abstract
Applicability of densification method by means of controlled blasting is examined by three field tests, and design formulae are proposed. Sand, silt and fill grounds are examined. Blasting is designed to install in the borehole which are arranged with several meters distance from each other, and fired with a little time lags. Water boiled out from the ground and the ground surface subsided after blasting. Since the SPT-N values increases according to the settlement of the ground, it can be used as remedial measures against soil liquefaction. The ground settled significantly just after the blasting, and terminates for several days. Duration of settlement increases up to several weeks as fines contents increases. Improvement of the ground strongly depends on the amount of blasting per unit volume. It is also affected by delay time and distance between boreholes. Although increase of SPT-N value becomes smaller as fines contents increase, the method is applicable to the ground with fines contents larger than 40 %. The vibration of the ground can be predicted from the data by single blasting or preliminary test, and vibration in the vicinity of the site can be reduced by controlling the blasting conditions.
