Abstract:
Sand fill beneath the structure and surrounding area should be well compacted to
make it non liquefiable. Once a structure is constructed on liquefiable soil, mitigation
measures become very expensive. Therefore, it is very important to control the quality
of sand fill so that structure would not be vulnerable to damage induced by seismic
liquefaction. Compaction control of sand fill is generally done by determining field
density using Sand Cone Method in Bangladesh. Sand Cone Method is expensive and
cumbersome to do after completion of compaction in every single layer. The present
study was aimed at developing an alternative indirect method which can be used to
determine Relative Density easier and faster for clean sand of any particle size.
The study consists of three stages. To know the height of fall and hole diameter of
sand discharging bowl for a desired Relative Density of a specific sand, the air
pluviation method was calibrated in the first stage. Then in the second stage sand
deposits of different relative densities were prepared in calibration chamber and
Dynamic Probing Light (DPL) and Dynamic Cone Penetrometer (DCP) tests were
performed on the prepared sand deposit. Correlation between Penetration Index (rate
of penetration in mm/blow, P;odcx)and Relative Density was made from the test results
in calibration chamber. At the last stage, the correlation was verified for two dredge
fill sites where DCP and DPL results were compared with the result from Sand Cone
Method.
A generalized correlation between P;odcxand Relative Density for clean sand of any
particle size was found from this study. To determine in situ Relative Density of sand
deposit, it is concluded that the proposed method (DCP and DPL) can be used as an
alternative indirect method which is suitable up to 2 m depth.
