【摘要】 为准确计算超大沉井取土下沉时沉井底部不同区域的端阻力，提出一种考虑沉井刃脚形态的端阻力计算方法。该方法将端阻力计算区域根据刃脚形态进行分类，分别采用不同的斜面投影面积折减系数计算不同类别计算区域的沉井端阻力。以常泰长江大桥为背景，研究其北塔沉井基础在首次取土下沉过程中的刃脚土压力分布规律，并根据实测数据，验证该方法的可行性。研究结果表明：沉井下沉过程中的刃脚土压力和端阻力均由中心区域向外侧区域转移，仅在外井孔开始取土后，存在小幅度的反向转移；由于刃脚形式存在差异，沉井不同区域刃脚所对应的斜面投影面积折减系数不同；单斜面和双斜面构造刃脚的折减系数推荐取值分别为0.45和0.61,采用折减系数推荐值计算的沉井端阻力和根据土压力监测值推得的折减系数计算的沉井端阻力最大相对误差小于9.5%,偏差较小。更多还原

【Abstract】 A method to accurately calculate the end resistance of different zones in super-large caisson base during soil excavation sinking is proposed. The method takes into account the shapes of the caisson cutting edges and classifies the end resistance calculation zones in accordance with shapes of cutting edges. Different reduction factors of oblique projection area are used to calculate the caisson end resistance in different calculation zones. The Changtai Changjiang River Bridge is applied as a case to study the distribution of soil pressure on cutting edges during the first soil excavation sinking of the open caisson foundation, and together with the measured data, the feasibility of the method was verified. The results show that during the caisson sinking process, the soil pressure and end resistance of cutting edges were mainly transferred from the central zone to the peripheral zones, and slight reverse transfer was found after the soil excavation in the peripheral wells. Due to that the shapes of the cutting edges are different, the reduction factors of oblique projection area corresponding to cutting edges in different zones are also varying. The recommended values of reduction factors for cutting edges with single inclined plane and with double inclined planes are 0.45 and 0.61,respectively. The relative error of the caisson end resistance calculated by the recommended reduction factors and the reduction factors derived using monitored soil pressure data is less than 9.5%,the deviation is small.更多还原