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马鞍山长江大桥北锚沉井体积巨大,下沉施工中有必要对其进行实时监测,主要监测内容包括刃脚与侧壁土压力、沉井结构钢板钢筋应力、沉井内外水位及沉井几何姿态等。首先采用数值分析,确定了沉井下沉初期为沉井结构受力的最不利工况,且边隔墙中跨部位为关键截面。监测结果表明,所选的关键截面较为合理。在沉井下沉初期,刃脚土压力对吸泥极为敏感。随着沉井的下沉,侧壁摩阻力逐渐增大,刃脚土压力趋于减小。沉井结构钢板与钢筋应力未出现过大拉应力,沉井几何姿态监测结果也表明下沉施工顺利。
The North Anchorage Caisson of the Ma’anshan Yangtze River Bridge is huge in size. It is necessary to conduct real-time monitoring during the construction of the submarine. The main monitoring contents include the pressure on the blade edge and the sidewall, the stress on the steel plate in the caisson structure, the water level inside and outside the caisson and the geometry of the caisson . Firstly, numerical analysis was used to determine the most unfavorable condition of the caisson structure subjected to the initial caisson sinking, and the midspan of the cavern is the key cross-section. Monitoring results show that the selected key section is more reasonable. In the early period of sunk shaft sinking, soil pressure on the edge of the blade is very sensitive to sucking mud. With the sinking of the caisson, the frictional resistance of the sidewall gradually increases, and the earth pressure on the blade edge tends to decrease. Caisson structure steel and steel stress does not appear excessive tensile stress, caisson geometric attitude monitoring results also show that the construction of the sunk well.