地铁下穿区域灌注桩成孔精度控制研究

Hole Forming Accuracy Control of Cast-In-Place Pile in Subway Underpass Area

旋挖钻孔灌注桩是一种在各类工程中广泛应用的桩基基础,工艺较为成熟,能够穿越各类复杂地层。但受到地质条件等外部因素影响,灌注桩偶现桩位偏移、斜桩情况。深圳市某水质净化厂工程建设区域内涉及到地铁盾构下穿,原有PHC管桩基础变更为灌注桩基础,一旦灌注桩发生偏位,整改难度高、代价大,且对结构安全与地铁施工均有不可预测的影响,因此对桩位、垂直度的控制有较高要求。在本工程中,主要应用GPS-RTK和垂球法对灌注桩成孔精度进行控制。

Rotary drilling cast-in-place pile is a pile foundation widely used in various projects,its technology is relatively mature and can pass through various complex strata.However,due to the influence of external factors such as geological conditions,the pile position offset and inclined pile of cast-in-place pile occasionally occur.Metro shield tunneling is involved in the construction area of a water purification plant in Shenzhen,and the original PHC pipe pile foundation is changed to cast-in-place pile foundation.Once the cast-in-place pile deviates,the rectification is difficult and costly,and has an unpredictable impact on structural safety and metro construction.Therefore,there are high requirements for the control of pile position and verticality.In this project,GPS-RTK and vertical ball method are mainly used to control the forming accuracy of cast-in-place pile.