预应力薄壁管桩螺旋钻土纠偏施工工艺.doc

预应力薄壁管桩螺旋钻土纠偏施工工艺

一、基本情况
某工程为框架七层，总长度为78.98m，总宽度为66.01m，建筑面积为17135㎡，分为A1，A2，A3栋，中间以裙楼相连，主楼与裙楼间设有后浇带和伸缩缝，按七度抗震设计,框架抗震等级为三级。
土质情况：根据地质报告反应，第一层为素填土，层厚0.30—1.80m，第二层为粉质粘土，层厚0.60—2.45m，第三层为淤泥质粘土，层厚14.00—25.50m，第四层为淤泥质粘土，层厚为1.90—6.90m，第五层为粘土，层厚为6.50—27.10m。
工程采用Ǿ400、 Ǿ550预应力薄壁管桩，桩长32m，采用静压成桩，施工后，经动测发现部分管桩上部断裂，桩顶严重偏位，最大偏位量达到610mm，为利用下部管桩的承载力需将上部断桩复位，然后在管桩内筒中浇灌配筋砼进行接桩补强。经对几种纠偏复位方法进行试验比较，最后选定螺旋钻取土纠偏施工方案。
二、取土纠偏专用工具
1、螺旋钻：由钻杆、螺旋叶片、转动手柄及连接件构成。钻杆的长度由钻孔深度要求确定，钻杆应能抵抗转动时产生的扭矩，本工程使用钻杆
Prestressed thin-walled spiral drill pipe construction technology soil correction

I. Basic
The framework of a project to seven, with a total length of 78.98m, total width of 66.01m, a building area of 17,135 square meters, divided into A1, A2, A3 Building, connected to the middle in order to skirt the main building is equipped with the podium after the pouring and expansion joints, seismic design by 7 degrees, frame seismic rating of 3.
Soil conditions: According to the geological report reaction, the first layer filling factor, thickness 0.30-1.80m, the second layer of clay, thickness 0.60-2.45m, the third layer is silty clay, thickness of 14.00- 25.50m, silty clay, the fourth layer, thickness is 1.90-6.90m, the fifth layer of clay, with the thickness 6.50-27.10m.
Works with Ǿ400, Ǿ550 prestressed thin-walled pipe, pile length 32m, using static pile, after construction, by the dynamic testing found that some of the upper pipe rupture, a serious deviation pile head, the maximum deviation amounted to 610mm, for the use of the lower part of the bearing capacity of pipe piles need to reset the top off, then the inner cylinder in the water in the pipe reinforced concrete for the pile reinforcement. The reduction of several methods of correcting experimental comparison, the final selection of spiral drill dug rectification construction program.
Second, take soil correction special tools
1, spiral drill: the drill pipe, spiral blades, turn the handle and connector form. The length of drill pipe to determine the drilling depth required, the drill pipe should be able to resist the torque generated during rotation, the use of drill pipe works