华南沿海地区桥梁摩擦桩基础沉降研究与处理

为解决华南沿海强风化岩地区桥梁摩擦桩基础沉降问题,以深圳某跨海大桥为例,对该类桥梁基础沉降原因进行分析并提出相应处理措施。该桥11个摩擦桩基础桥墩在箱梁架设后均产生了不同程度的基础沉降。对最大沉降量为42 mm的桥墩桩基础进行钻芯取样分析并对该墩地基承载力进行验算。针对实际情况提出在该桥墩桩底进行压力注浆的处理措施,然后采用静载试验验证该措施的效果。结果表明:该桥墩基础出现沉降的主要原因是基础的持力层(强风化辉绿岩)遇水软化,造成地基承载力下降;桩底压力注浆后该基础的后续沉降量不足1 mm,说明该处理措施取得了良好的效果。

Study and Handling of Settlement of Bridge Frictional Pile Foundations in Coastal Area in South China

To cope with the problem of settlement of bridge frictional pile foundations in the strong weathered rocks in the coastal area in south China,a sea-crossing bridge in Shenzhen was cited as an example,the causes leading to the settlement of the foundations of such type were analyzed and the corresponding measure for handling the settlement was proposed.Of the sea-crossing bridge,the settlement of the frictional pile foundations of 11 piers of different degrees was observed after the box girder of the bridge was erected.The core of one of these foundations having the greatest settlement amount of 42 mm was sampled by drilling,analyzed and the bearing capacity of the ground base of the foundation was checked by calculation.In the light of the specific conditions of the foundation,the measure for handling the settlement by base grouting for the piles therein was taken and the effect of the measure was then verified by the static load test.The results of the analysis and test show that the primary cause leading to the settlement of the foundation is that the bearing stratum(strong weathered diabase) of the foundation becomes softened because of water,which in turn causes the bearing capacity of the ground base to decrease.After the piles of the foundation are base grouted,the successive settlement amount of the foundation is not up to 1 mm,proving that the effect of the measure is sound.