Effects of Construction Technology on Bearing Behaviors of Rock-Socketed Bored Piles as Bridge Foundations

摘要

Construction technology has a considerable impact on the bearing behavior of bridge pile foundations. Considering practical bridge engineering, this study examined the mechanical characteristics of rock-socketed bored piles under different pile-forming methods using a self-balanced load test and explored the postgrouting effect on the load capacity of the piles. The results indicated that the dry rotary drilling pile method was conducive to ensuring the bearing strength of rock-socketed bored piles in bridge foundations, whereas the mud rotary drilling pile method significantly reduced the shaft resistance of rock-socketed bored piles as well as the pile-end resistance. The mud rotary drilling pile method also increased the settlement from the negative impact of sediment and the softening of carbonaceous shale. The postgrouting technique can effectively enhance the unit-shaft and end resistance of the rock-socketed bored pile and reduce its settlement by approximately 42 and 100% bearing capacity increment compared with dry and mud rotary drilling piles, respectively. Under their respective ultimate loads, the settlements also decreased by 37.5 and 54.4%. The postgrouting technique had a tremendous impact on the proportion of the end resistance to the shaft resistance, markedly increasing the end resistance for mud rotary drilling piles. These results provide an important reference for the design and construction of rock-socketed bored piles with a large diameter and length in bridge foundations. (c) 2019 American Society of Civil Engineers.