为改善目前基桩承载力试验中位移测试方法的经济性和便捷性,以既有连通管原理为基础,提出差压连通管式位移测试方法,建立测点位移与差压连通管内压差的变化量的关系,从而通过测量半封闭式连通管两端液体表面处的气压差变化实现对基桩试验时竖向位移的测量.结合实际工作要求,研发该方法的位移测量设备,并通过与步进电机控制式移动平台及百分表对应的测试试验验证了该方法的准确性.将该方法应用于某大桥自平衡法试桩工程中,结果表明:① 测试期间无需基准梁,无安装垂直度要求,可降低试验成本;② 与电子位移传感器测量结果一致,最大差值0.24 mm,说明应用该方法进行基桩承载力试验中的位移测量具有较好的经济性和可行性.%To improve the economy and simplicity of the current displacement measurement methods for testing of the bearing capacity of the foundation piles,a displacement measurement method of the differential pressure connecting pipe kind was proposed on the basis of the existing connecting pipe principle.The relationship of the variation amounts between the displacement of the measurement points and the pressure differences in the differential pressure connecting pipe was established and the vertical displacement of the foundation piles in the testing could be then measured by means of measuring the air pressure difference variations on the liquid surfaces at both ends of the semi-closed connecting pipe.In accordance with the real work demand,the displacement measurement equipment accommodating to the proposed method was developed and the accuracy of the method was verified through the testing corresponding to the mobile platform controlled by the stepper motor and the dial gauge.The method has been applied to the self-balanced load testing of the piles of a bridge and the results of the application show that (1) in the testing,the datum beams and installation verticality are not required and the method can therefore reduce the testing cost;(2) the measurements of the method are accordant with those of the electronic displacement sensors and the maximum difference value is 0.24 mm,which further shows that the method has rather good economy and feasibility when applied to the displacement measurement in the testing of the bearing capacity of the foundation piles.
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