Abstract: In order to reasonably improve the projet schedule and to reduce the construction cost, the based on a survey project in Tianshui, the pile foundation was optimized by static pile loading tests so that the pile bearing layer and construction technique were able to be selected. The results show that the gravel soil stratum is relatively dense in the construction site so that the pebble layer ④ as the bearing layer for piles is appropriate; As the bearing layer, the pebble soil layer is obviously better than that of the interbedded layer ⑤ of the strongly weathered to moderately weathered mudstone and conglomerate, which can be also used as the pile end bearing layer. In addition, the settlement stability of the test pile under the external load is better than that of the test pile without post grouting.

Key words: tianshui, river valley floodplain, piled foundation, optimization