以在建的世界最大跨径(575 m)钢管混凝土拱桥平南三桥北岸拱座基础工程为依托,采用袖阀管注浆技术对拱座基础持力层——饱和砂卵石层进行加固处治,并采用浅层平板载荷试验及现场大型直剪试验对处治后的砂卵石层地基的地基承载力和混凝土与砂卵石层注浆固结土体接触面的摩擦系数进行检测,以验证袖阀管注浆技术用于饱和砂卵石地层加固处治效果。研究结果表明,工程所采用的袖阀管注浆工艺显著提高了卵石层承载性能和摩擦性能。相关经验及成果可为西江流域或相似地质条件下修建大跨桥梁基础提供重要的参考资料,并对此类基础形式的优化设计施工工作提供依据。

The sleeve-valve-pipe grouting technique was applied to strengthening the saturated sandy gravel stratum, which is the load-bearing stratum for the foundation project of the Pingnan Third Bridge, the largest span (575 m) CTST (concrete-filled steel tube) arch bridge under construction in the world. Shallow plate load test and large-scale shear test were carried out to check the bearing capacity of the reinforced sandy gravel stratum and the friction coefficient of the contact surface between concrete and reinforced sandy gravel stratum. The purpose of the tests was to verify the effectiveness of sleeve-valve-pipe construction technique for strengthening the saturated sandy gravel stratum. Results indicated that the grouting had greatly improved the carrying capacity and frictional cofficient of the sandy gravel stratum. The research findings offer important reference for the construction of long span bridge foundation in Xijiang River Basin under similar geological conditions, and hopefully provide basis for the optimization design and construction of such foundation form.