基于土压力监测值的超大沉井下沉端阻力计算与分析  

End Resistance Calculation and Analysis of Super-Large Open Caisson During Soil Excavation Sinking Based on Monitored Soil Pressure Data

作　　者：董学超 郭明伟[1,2] 蒋振雄 王水林 陈哲文[1] DONG Xue-chao;GUO Ming-wei;JIANG Zhen-xiong;WANG Shui-lin;CHEN Zhe-wen(Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Jiangsu Provincial Transportation Engineering Construction Bureau,Nanjing 210004,China)

机构地区：[1]中国科学院武汉岩土力学研究所,湖北武汉430071 [2]中国科学院大学,北京100049 [3]江苏省交通工程建设局,江苏南京210004

出　　处：《桥梁建设》2022年第5期78-84,共7页Bridge Construction

基　　金：交通运输行业重点科技项目(2019-MS1-011)。

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。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.

关 键 词：桥梁工程 超大沉井基础 取土下沉 刃脚形式 刃脚土压力 端阻力 计算方法 施工监测 

分 类 号：U443.131[建筑科学—桥梁与隧道工程] U445.557[交通运输工程—道路与铁道工程]