强风化花岗岩中钻孔扩底灌注桩承载性状试验

Experimental Study on Bearing Behavior of Bored Belled Piles in Strong Weathered Granite

对3根埋有应力测试元件的钻孔扩底灌注桩静载试验结果的分析表明，在竖向荷载的作用下，桩底土压力的分布规律为中部大、两边小（〉6000 kN），桩端扩大头上斜面土压力随桩身沉降增大而减小，各土层侧摩阻力达到极限时所需桩顶位移为12-19mm。试验还表明，桩侧摩阻力达到最大值后的“软化”现象非常明显，根据试验实测数据的计算，软化后的侧摩阻力衰减为20％～30％，各土层侧摩阻力实测值也普遍比规范给定的理论计算值小9-17％。

This paper describes static loading test in three numbers of belied piles. The analysis of test resuits shows that the basic resistance distribution is a peak in the central and reduction in the edge under vertical loading. The ground pressure on the upper inclined surface of the belled pile shall reduce while the pile settlement increases. The frictional resistance shall achieve the peak while the settlement of the piles reaches 12 mm to 19 mm. The experiment also indicates that when the pile side friction reaches its maximum, the ＂softening phenomenon＂ becomes obvious. According to the calculation of the experimental measured data, the frictional resistance was weaken by 20%--30%, and the actual measured value of various soil layers was generally smaller than the theoretical value assigned by the standard by 9%- 17%.