沉井下沉阻力离心模型试验研究

Study of sinking resistance of large and deep caisson based on centrifugal model test

如何正确计算沉井的下沉阻力一直是沉井结构设计的难点,为了更加深入地研究沉井下沉阻力及其分布规律,通过离心机模型试验分别对4组不同埋深工况下的沉井进行了下沉模拟,对沉井侧壁土压力、刃脚斜面土压力、刃脚踏面土压力、沉井内外土面沉降进行了分析。研究结果表明:侧壁土压力随入土深度的增加呈先增大后减小的趋势,可采用分段函数形式对其大小及分布形式进行简化计算;刃脚斜面土压力呈三次多项式分布形式;随着刃脚入土深度的增加,刃脚斜面与踏面土阻力均显著增大,而单位投影宽度刃脚斜面与踏面土阻力比基本保持不变;沉井下沉会导致井外土面沉降,井内紧靠沉井内壁的土面沉降,离沉井内壁有一定距离的土面隆起。上述试验与分析成果可为理论研究与工程设计提供参考。

How to correctly calculate the sinking resistance of caissons has been a difficult problem in the design of caisson structure.In order to comprehensively study the sinking resistance and distribution law of the caisson,the sinking simulation of the caisson in four different depth conditions is carried out through the centrifuge model test.Side pressure,earth pressure on foot blade incline,earth pressure on tread of foot blade and deformation of the earth surface have been analyzed.The results show that the side pressure increases first and then decreases,and its value and distribution can be simplified by piecewise function.Distribution of earth pressure on foot blade incline is cubic polynomial.With the increase of the depth of the foot blade,the soil pressure of incline and tread significantly increases,and the resistance ratio of incline and tread per unit width remains the same.Sinking of caisson will lead to subsidence of the earth surface outside the caisson,subsidence of the earth surface adjacent to caisson wall inside the caisson,and uplift of the earth surface which has a certain distance away from the caisson.The experimental and analytical results reported in this study can provide reference for theoretical research and engineering design.