扩孔微型桩抗震性能试验研究

对6根具有不同扩孔参数的微型桩进行室内足尺低周循环侧向加载试验,得到滞回曲线和骨架曲线,并计算耗能能力和延性系数,对其抗震性能进行评估.所得结论可为新型抗震型半整体式桥台桥梁的实际应用打下基础,对整体式桥台桥梁支承桩的扩孔技术也有一定借鉴意义.

Experimental investigation on seismic performance of micropile with predrilled oversize hole

Indoor full-scale cyclic lateral loading experiments of 6 micropiles with different predrilled-hole parameters were carried out.From the experiments, their hysteresis curves and skeleton curves, as well as energy dissipation capacity and ductility were obtained to reflect seismic performance. The following conclusions can be drawn: 1) in the elastic stage, the hysteresis curves look like spindle and its dissipation capacity is small. In the elastic-plastic stage and failure stage, the hysteresis curves seem like full bows, showing good seismic energy dissipation capacity; 2)the predrilled hole of micropile has effects on energy dissipation that the increasing of predrilled-hole aperture slightly improves it; that the variation of predrilled-hole depth in small range has little influence on it; and that the loose material compactness of predrilled hole improves it greatly; 3)the ductility coefficients of micropiles with different predrilled-hole parameters are between 2.45 ~ 3.67. All of the micropiles with predrilled oversize hole show lower ductility. the aperture and the material compactness of predrilled holes have little influence on their ductility. The increasing of predrilled-hole depth is helpful to improve the ductility. These conclusions will make contribution to the practical application of proposed aseismic semi-integral abutment bridge and provide reference for the hole-predrilling technology in integral abutment bridges.