An in situ low-pressure grouting application

This study examined the effects of low-pressure grouting on soil properties at a site that is at risk of soil liquefaction. The study was conducted at a 96 m² site located in Yalova, Turkey, that is considered a first-degree seismic zone. Compaction grout was injected into a silty sand layer at 100 kPa and 150 kPa pressure at three different points at depths of up to 9 m. Standard penetration tests, cone penetration tests and seismic refraction tests were conducted before and after the grouting, to determine the effect of grouting on the soil properties in the field. Grout injection holes were drilled at a spacing of 1·25–3·0 m. Grout injection was observed to be impossible in wells that were spaced closer than 1·50 m, because of the diffusion of grout from primary injections. The injected grout volume was calculated to be 5% of the total soil volume. The results from the tests indicate that the bearing capacity of the soil increased by approximately 50%, and the safety factor with respect to liquefaction increased by a factor of up to 100%.