DX挤扩灌注桩及其竖向承载力的若干问题

DX PILE AND ITS SEVERAL PROBLEMS OF VERTICAL BEARING CAPACITIES

对DX挤扩灌注桩的产生、类型、特点、承力盘(岔)设置原则、极限承载力的综合评价、竖向抗压承载力的计算、桩身强度验算及DX液压挤扩装置的构造给予介绍。依据24根DX挤扩灌注桩和3根大比例尺现场模型DX桩的静载荷试验的资料,系统阐述DX桩轴力传递的规律和特点;详细论述在极限状态和工作状态时总侧阻力、总盘端阻力和总桩端阻力的发展及分配规律以及桩身各分段单位侧阻力;承力盘单位盘端阻力和单位桩端阻力的发展规律。并对DX挤扩灌注桩与等直径钻孔灌注桩的荷载传递机理及抗压和抗拔承载力机理进行对比。最后对如何保证实施完整的静载荷试验,以获得有用的荷载传递资料给予论述。

It is introduced that the derivation,types,characteristics,principles for the location of the bulbs and branches,comprehensively estimating method for ultimate bearing capacity,calculation formula of vertical compressional bearing capacity,calculation formula of compressive bearing capacity of shaft of DX pile and structure of DX extruding device.Through the static loading tests for 24 DX piles and 3 DX piles with large scale field model,where the reinforcement stress detectors or electrial resistance strain gauges were embedded, the regular patterns and characteristics of mechanisms of bearing capacity of DX piles are systemically studied, and the developments and the distributions of the skin-friction resistances, the bulb resistances and the tip resistances under ultimate and working conditions are detailedly analysed, the developments of the unit skin-friction resistances of each sections of DX piles and the unit bulb resistances and the unit tip resistances of DX piles are systemically studied. The differences of load transfer mechanisms between DX piles and uniform bored piles, and the differences of mechanisms between compressive and tensional DX piles are also comparatively analysed. Finally, how to guarantee the static loading test so that to obtain the full useful data of the mechanisms of bearing capacities also are indicated.