修井机地锚桩抗拔承载能力试验研究

Experimental study on uplift resistance of earth anchor piles for oil work-over rig derrick

地锚桩经由绷绳与井架相连,是修井时固定安放修井井架的重要组成部分,其桩基抗拔承载力直接关系到修井作业和人员安全。大庆油田现用地锚桩主要形式为普通油管桩,其极限承载力主要为桩侧摩阻力。为使修井地锚桩具有足够的承载力以保证修井安全,运用振动和机械阻抗测试方法,对不同土况下桩承载力进行试验,通过计算机械导纳和动刚度,得到大庆油田采油区域地锚桩承载能力与土质条件的关系:黏土桩承载力最大,砂土次之,低洼湿地和建筑回填土较差。解释了地锚桩拔桩过程中桩土作用机理和侧摩阻力非线性变化规律。采用直接拔桩方法对测试结果进行验证,说明机械阻抗法可推广应用于此类等截面抗拔桩的承载力研究,为油田地锚桩安全施工提供理论依据。

The earth anchor pile is the most important part to fix the derrick on the oil work-over rig, which is con- nected with steel wire ropes during the work-over operation. Its bearing capacity concerns the safety of workers and work-over equipment. The oil pipes are ordinarily made into the anchor piles. The main part of the pile＇ s ultimate bearing capacity is pile side friction. To ensure the fixing quality of the whole derrick, the anchor piles must have great bearing capacity. The experiments on anchor piles in different soil conditions are done by using the methods of vibration and mechanical impedance test. After calculating the piles＇ mechanical impedance and dynamic stiffness, the results of relations between the bearing capacities of anchor piles and soil conditions are got. The greatest bear- ing capacity of anchor pile is in clay soil, then in sandy soil, and the least is in low-lying wetland and construction backfill soil. It explains the mechanism of soil-pile interaction and the nonlinear law of pile side friction. The direct pile oulling method is used, which verifies the validity and accuracy of the mechanical impedance test, and is worth popularizing in the type of uniform section piles research. It can provide a help to prevent the anchor piles from be- ing pulled out the earth during the oil tubes moving up and down, and ensure the safety operation.