Abstract:
This research aims at studying the settlement behavior of a road on cement column improved soil during the construction at EGATs reservoir powerplant. Many types of geotechnical instruments which are surface settlement plate, deep settlement point, open standpipe, closed hydraulic piezometer and digitilt horizontal inclinometer, were installed before the construction in order to measure the settlements and excess pore pressure. From the recorded data during 296 days, it is found that the maximum value of settlement occurred at the center of the road with the magnitude of 4.18 cm (soil without improvement). The comparison of the settlement measured at the center of the road between improved soil (at the top of cement column) and soil without improvement indicates that the settlement was reduced by 50 percent if soil was improved by cement column. In the analysis based on Terzaghi Method, the predicted settlement of improved soil can be reduces by 67.40 percent of soil without improvement. In case of settlement prediction by using three methods, which are One Dimensional Method, Broms and Boman Method, Asaokas Method. The Asaokas graphical method yields a good correlation with the data field. The calculated error is 12.7 percent at 296 days. The vertical consolidation coefficient from Asaokas graphical method yields, cv(Field) = 8cv(Lab). From the slope stability analysis of improved-soil road, the obtained safety factor is 1.84.