润扬桥基三维裂隙网络渗流数值模拟

Numerical simulation of fracture network seepage of rock masses of Runyang Bridge abutment

润扬长江大桥北锚碇是大桥关键工程,承担大桥悬索较大拉力。北锚碇的基础为花岗岩裂隙岩体,分布断裂和多组裂隙,基岩表部风化,上覆约45m厚的第四系松散沉积层,基坑开挖深度达48m,基坑内外水头差达47m。如何做好防渗和排水,对施工期的安全和施工质量至关重要。为此,采用离散裂隙网络渗流的三结构模型与连续介质渗流模型相结合,对北锚碇场区的地下水渗流进行了多种工况的数值模拟,为基坑防渗和排水设计提供了主要参考依据,其数值模拟结果已得到后来施工期实际资料的验证。

Runyang Bridge is an important part of the whole transportation network of the Yangtze River, and its north abutment is the key part of the bridge, because it will support a large pulling force. The foundation of the north abutment is composed of the fractured granite rock, the top of which was weathered, and was covered by Quaternary loose sediments of 45m. The pit of the foundation is 48m deep and the water head drop between inner and outer of the pit is 47m. So designing of anti-seepage and drainage is very important for the security and the quality of construction. Therefore the combination of the model of discrete fractnre networks （so-called the model of three type fractnres） and the model of porous medium is applied in simulating the seepage flow of the rock and Quaternary sediments for several conditions of groundwater seepage. The results gave valuable guidance for the pit seepage control and drainage design, which have been validated by the data of construction period.