Performance evaluation of post-grouting for bored piles installed in inhomogeneous gravel pebble stratum overlaid by deep and soft soil layers

To study the behaviours of post-grouted piles installed in an uneven pebble bearing layer overlaid deep and soft soil layer in Wenzhou, China, static loading field tests of three bored post-grouted piles were conducted, considering the key design parameters of post-grouting including the grout volume, grout pressure, and bearing capacity. According to the on-site geological conditions in the region, the theoretical values were calculated through applying different calculation equations for these three parameters, and the actual values obtained from the field tests were investigated to assess the improvement effect of load-bearing performance of grouted piles installed in these geological conditions as an extremely uneven pebble-bearing layer overlaid by the deep and soft soil layer. The calculation equations of key design parameters of post-grouting in this type of soil layers were then proposed. This study could provide a reference to evaluate the performance of post-grouted piles under various grouting parameters in analogical soil layers.