试论大口径灌注桩施工中扶正器与充盈系数的关系

在复杂地层中施工超深大口径钻孔灌注桩时,常因充盈系数增大而使成本居高不下.为解决温州世贸中心大厦桩基项目施工中的实际问题,从钻杆的屈曲理论出发,采用能量法分析钻杆的稳定性,建立了钻杆扶正器放置间距方程.同时应用该理论在工程中进行了初步试验,并在其他因素不变的情况下增大转速、钻杆柱底部的轴向压力和线重度中的任意一项,扶正器与钻头之间的安放间距均减小.

Relationship of Filling Coefficient of Large-Diameter Bored Pile and the Place of Centralizer

The application of bored piles with large-diameter and super-depth to complex stratum often costs more than expected because of large filling coefficient. In an attempt to decrease the filling coefficient of Wenzhou International Trade Center pile foundation project, we have adopted a centralizer on the drill string. After a through interpretation of drill string stability, the equation of length between drill bit and centralizer is obtained. We have described the experiment based on the equation and discussed a more comprehensive study on the impact caused by the change of rotary speed,pressure and gravity permeter rod.