长螺旋钻孔压灌混凝土抗压抗拔构件承载性状试验研究

Experimental study on bearing properties of compression and uplift components with long spiral drilled compression grouting concrete

为了研究长螺旋钻孔压灌混凝土工艺制成的抗压桩与无自由段复合锚杆的极限承载力、轴力、侧摩阻力的分布规律以及两者之间的联系,在现场进行了两组足尺试验;通过在抗压桩和复合锚杆内设置钢筋计,测出各级荷载下桩身/杆身不同深度的应变,推算出其轴力和侧摩阻力,进而对抗压桩和复合锚杆的受力机理进行了分析。分析结果表明,抗压桩和复合锚杆的侧摩阻力都是从上部开始发挥并向下部传递的,其中抗压桩桩端阻力对桩侧摩阻力表现出强化效应;复合锚杆的受力模式不同于普通的抗拔桩和抗浮锚杆,试验中杆身轴力峰值与张拉极限荷载的比值约为2/3。最后根据试验分析结果和《建筑桩基技术规范》（JGJ 94—2008）,提出了长螺旋钻孔压灌混凝土工艺下复合锚杆极限承载力的估算方法。

In order to study the distribution laws of ultimate bearing capacity,axial force,side friction resistance and the connection between compression piles and free-section composite anchors made by long spiral drilled compression grouting concrete technology process. Two full-scale tests were conducted in the field. By setting the steel bar gauges in the compression piles and composite bolts,the strains at different depths of the pile/shaft under different loads were measured,and its axial force and side friction resistance were calculated. And then the stress mechanism against the compression pile and composite anchor were analyzed. The analysis results show that the lateral frictional resistance of the compression pile and the composite anchor are both transmitted from the upper part to the lower part,and the pile end resistance of the compression anchor shows the strengthening effect on the pile side resistance; the force pattern of the composite anchor is unlike the ordinary uplift piles and anti-float anchors. The ratio of the axial peak force of the shaft to the tensile limit load is approximately 2/3. Finally, according to the experimental analysis results and Technical code for building pile foundations（ JGJ 94—2008）,the method for estimating the ultimate bearing capacity of composite anchor under the process of long spiral drilled compression grouting concrete technology was put forward.