基于隔时复压试验的静压桩优化设计方法  

Optimum design method of jacked piles based on interval re-pressed test

作　　者：张明义[1] 刘俊伟[2] 张忠苗[2] 于秀霞 

机构地区：[1]青岛理工大学土木学院,山东青岛266033 [2]浙江大学岩土工程研究所,浙江杭州310058 [3]青岛万合建筑设计有限公司,山东青岛266520

出　　处：《岩土工程学报》2010年第2期320-324,共5页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(50678086)

摘　　要：桩的承载力随时间变化的现象称为承载力时间效应,现有设计方法没有全面考虑此方面的影响。利用静力压桩机方便移机的特点,对桩进行复压使其产生一定的贯入度,以确定任意时刻的广义极限承载力,称之为隔时复压试验,其特点是以减少后期沉降和提高承载力为目的的复压方法。珠海、太原隔时复压试验的结果显示,承载力增长趋势是明显的。将隔时复压的结果与广泛采用的Skov和Denver的承载力增长经验关系式对比,发现两者的相关性显著,并得到了时效系数的分布范围。通过较短时间内的隔时复压结果,确定长期承载力增长规律,并运用到静压桩的优化设计中,同时采用复压调节系数和安全系数对结果进行修正,以提高设计方法的准确性。详细介绍了优化设计的思路,并以太原某工程为例证明了此方法的可行性。此设计方法对降低施工难度、缩短工期、节约成本、保证设计的可靠度都具有重要意义。The Change in pile capacity with time after installation which is usually referred to time effect or set-up,and the decrease in pile capacity with is termed as relaxation are rarely incorporated in the present design method.The singular ultimate-bearing capacity can be confirmed when the completed piles are repressed at specified time by the convenient pile jacking machine,which is named as the method of interval re-pressed tests and it is different from the traditional re-pressed construction draft.Based on the collected data from Zhuhai and Taiyuan,pile set-up is significant and continues to develop for a long time.The Skov and Denver＇s equation is adopted to predict the change trend of axial pile capacity with time,and the reliability of this method is testified and the range of A value is confirmed by the results of interval re-pressed tests.The characteristics of predicted set-up capacity are described by the interval re-pressed test results in short term after the initial installation,which is incorporated into the design to optimize the proposal.Meanwhile the accuracy of the method is improved by employing dimensionless setup factor and safety factor.High feasibility of the design process is presented and proved by the design case in Taiyuan.The proposed design method is meaningful to reducing the construction difficulty,decreasing the construction period,saving the cost and improving the reliability of design.

关 键 词：静压桩 优化设计方法 最终压桩力 隔时复压 承载力时间效应 

分 类 号：TU473[建筑科学—结构工程]