用机械阻抗法确定作业井架地锚桩的极限承载力

由于油田井下作业井架为一两腿落地的空间钢架结构，需要用绷绳作支撑，所以用于固定油田井下作业井架绷绳的地锚桩，其抗拔极限承载力的研究与确定对保证井下作业安全至关重要。本文用机械阻抗法对井下作业系统中地锚桩的极限抗拔载荷进行了测试与研究。采用瞬态激励法，用变时基技术分别测试了4种规格尺寸的油管桩和一种规格尺寸的水泥桩在瞬态激励下的速度信号，进行变时基传函分析得出动刚度，确定了极限承载力。结果分析表明，在大庆油田粘性土使用条件下，水泥桩的极限抗拔拉力很大，完全可以满足井下作业需要；不同尺寸油管桩的极限抗拔拉力差异较大，井下作业时应使用2．5m以上长度的油管桩。

Ultimate pull bearing capacity of anchor pile on working derricks determined by mechanical impedance method

It is very important to research and determine the ultimate bearing capacity of anchor pile to ensure the safety of downhole operation, which is used to fix the guy wires on working derricks in oil fields. The ultimate bearing capacity of anchor pile in downhole operation system is studied in this paper. Velocity signals of four kinds of oil pipe piles and a kind of cement pile under instantaneous impulsion are measured by using instantaneous impulsion method and variable time base technology. Based on analyzing variable time base transfer function, dynamic stiffness is gotten, and the ultimate bearing capacity is determined. The result shows that the ultimate bearing capacity of the cement piles is large enough to meet the requirement of the downhole operation fully, and the ultimate bearing capacities of the oil pipe piles of different sizes are different, and the oil pipe piles, which are longer than 2.5 meters in downhole operation are recommended.