嘉绍跨江大桥水中区引桥单桩独柱墩设计

Design of Single Pile Single Column Piers of Approach Bridge of Jiashao Bridge over North Shore Water Area

由于建设条件的特殊性,嘉绍跨江大桥70 m跨径水中区引桥采用没有承台构造、墩柱和大直径桩基础直接连接的单桩独柱下部结构方案。该方案主墩墩、梁固结,横桥向两幅桥之间主墩墩顶设置了工字形截面混凝土横系梁;钢护筒全长45 m,底口、顶口标高分别为-35 m、+10m;桩基础直径3.8 m,单桩桩长105～111 m,均按摩擦桩设计,桩基础采用C30海工水下混凝土;主墩采用圆柱形墩,墩顶断面宽8.5 m,圆端直径与墩底断面直径相同,墩柱采用C40海工混凝土。

Owing to the particularity of the construction conditions,the 70-m span approach bridge of the Jiashao Bridge over the north shore water area employs the scheme of the single pile single column structure without pile caps and with large diameter pile foundations directly connected with the pier columns.In the scheme,the piers and girder are rigidly connected and the I-shape concrete cross tie beams are provided at the pier tops in the transverse direction of the two separated bridge decks.The total length of a steel casing for the bored pile is 45 m,the elevation at bottom opening and top opening of the casing is respectively-35 m and ＋10 m.The diameter of a bored pile is 3.8 m,the length of a single bored pile is 105～111 m.All piles are designed as the frictional piles for which the C30 marine tremie concrete is used.The piers are the column shape piers,the width of the cross section at a pier top is 8.5 m and the round end diameter of the pier is the same with that of the cross section at the pier footing,for which the C40 marine concrete is used.