Abstract:The behaviors of bearing capacity and settlement of bored piles in two different depth bearing layers with/without end post-grouting are studied contrastively through static load tests for piles with different lengths in a certain engineering practice of Ningbo City. The study results show that if the 8th soil stratum—silty soil is selected as bearing layer,the pile length is 55 m and employing pile end post-grouting can increase the bearing capability and decrease the pile top settlement remarkably;although selecting the 13th soil stratum—sandy gravel embedded with clay as bearing layer,where there is bedrock below,it can prevent pile end from plunge failure effectively. Therefore the pile length is 88 m and it is very difficult to penetrate the silty sand stratum during installation,which is about 20 m in thickness. Therefore,the construction quality is hard to control. This makes mudcakes around piles at pile ends too thick,resulting in decreasing of the bearing capability of single pile and failure to meet design requirements. The technical economic analysis is made quantitatively and the selection of pile bearing layer is optimized. In order to guarantee the safety of engineering piles,it should reduce the cost as minimum as possible and make pile installation convenient. The silt soil stratum is finally selected as the bearing layer.