Determination of the relative soil compactness in the foundation condition by microgravity data

Low-density zones with high void ratio can be detected in the foundation condition by microgravity data. After collecting the data and using standard corrections methods, Bouguer anomalies are computed. Residual anomalies are obtained by removing the trend or regional anomalies from Bouguer anomalies. Negative anomalies are quite distinguishable in residual anomalies map. One of the most important causes of lowdensity zones is the decrease of soil compactness due to the high void ratio. These detected low-density or low-compacted zones should be grouted before any kind of construction. These zones are associated with lows in microgravity data and relative negative anomalies consequently. These detected negative anomalies seem to be inter connected in some way. This connection advocates the hypothesis of a common source for these anomalies. The detected low-compacted zones are examined and confirmed by a few number of test pits. One of the pits encountered an underground man-made water supply. Some other test pits encountered loose or low-compacted zones that were filled with water after a few hour of drilling, originated from the detected man made water supply.