Statistical Analysis of Bored Piles with Pile-Bottom Post Grouting

The statistics of cement consumption, bearing capacity, and settlements for pile-head and pile-toe are obtained by using the comparison of over 600 piles with or without grouting. The statistical results show that post grouting technique is most used in gravel and pebble stratum (taking up 67.8%), followed by silty sand (taking up 20.3%), and can also be used in silt and clay and bedrock. The post grouting technique is used in bedrock to solidify rock mass and sediment. By regression analysis of piles in gravel and pebble stratum or silt, the cement consumption is found to be linear with the square of pile diameter. Enhancement coefficient of post grouting pile's bearing capacity is 1.25 in silt and clay, 1.31 in silty sand, 1.46 in gravel and pebble stratum, and 1.16 in bedrock, respectively. For piles with the same diameter, the improvement of bearing capacity in gravel and pebble stratum is the biggest. By post grouting, the settlements of pile-head and pile-toe can be reduced by 24%similar to 37% and 49%similar to 78%, respectively.