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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 phenomenon that the bearing capacity of pile changes with time is called the time effect of bearing capacity, and the existing design method does not fully consider the influence of this aspect. The use of static pile driving machine to facilitate the transfer of the characteristics of the pile re-pressure to produce a certain degree of penetration, in order to determine the generalized ultimate load at any moment, called interval pressure test, which is characterized by a reduction Post-settlement and increase the carrying capacity for the purpose of the complex pressure method. Zhuhai, Taiyuan interval pressure test results show that the increasing trend of bearing capacity is obvious. Comparing the results of interval recuperation with the empirical correlations of the widely used growth rates of Skov and Denver, we found that the correlation between the two is significant and the range of distribution of the aging coefficient is obtained. The law of long-term bearing capacity growth is determined by the results of interval-time recompression in a relatively short period of time. The optimal design of static pressure pile is applied to the optimization design of the static pressure pile, and the results are corrected by the coefficient of re-regulation and safety factor to improve the accuracy of the design method Sex. The idea of optimal design is introduced in detail, and the feasibility of this method is illustrated with an example of a project in Taiyuan. This design method is of great significance to reduce the difficulty of construction, shorten the construction period, save costs and ensure the reliability of the design.