The load is applied to the column by dead weights such as sandbags or pig iron on lead bars or by a reaction frame which may be anchored to the soil by means of anchors or centered with steel joists. Can be jacked up against a heavily loaded platform. The bottom hydraulic jack should be butted against the joist with a ball bearing in the middle. The load is increased regularly to 200 kg or approximately one-fifth of the ultimate bearing capacity or until the ultimate load is reached.
The settlements should be recorded at least to an accuracy of 0.02 mm with the help of at least two dial gauges to take care of any differential settlement that may occur. Settlements should be observed for each increment of load after an interval of 1, 4, 10, 20, 40, 60 minutes and thereafter at hourly intervals. In the case of clayey soils, the time-settlement curve should be plotted at each load stage and the load should be increased to the next stage either when the curve indicates that the settlement has exceeded 70–80 per cent of the expected ultimate settlement at that stage or at the end of a 24-hour period. For soils other than clayey soils, each load increment shall be kept for not less than 1 hour and up to the time when no further measurable settlement occurs. The next increment of load shall then be applied and the observation is repeated
Leave a Reply