不均匀复杂地质条件下承台深基坑支护及止水结构研究

依托成都世纪城路东延线府河桥#2索塔承台深基坑工程，研究不均匀复杂地质条件下承台顶面低于施工水位的深基坑支护及止水结构。经过比选，主塔承台深基坑采用钢筋混凝土排桩+高压旋喷桩支护结构方案。通过 CFG 桩机改装，钻头改换成潜孔锤成孔，将常规旋喷桩先引孔后成桩工序，改变为成孔后直接喷浆成桩工序，提高了施工工效，降低了施工成本。

Study on Supporting and Water Stopping Structures of Deep Foundation Pit for Bearing Platform under Heterogeneous Geological Conditions

For the purpose of studying the supporting and water stopping structures of deep foundation pit which locate in sand layer and large size sandy pebble layer with heterogeneous geological conditions and have the top of bearing platform lower than the water level in construction, the foundation pit engineering for the cable tower 2# of Fuhe Bridge on East Extension Line of Century City Road, Chengdu was taken as the background. Depending on the comparison of schemes, it was determined, first, to adopt reinforced concrete pile row plus high pressure jet grouting pile to be the supporting structure for the foundation pit of main tower; second, to modify the drilling rod of CFG pile machine with down-the-hole hammer to be the drill bit; third, to change the processing steps of grouting pile from the conventional two steps, i.e. first hole guiding then pile forming, to one step, i.e. directly pile forming by grouting after drilling, all of which improved the work efficiency and reduced the construction cost.