临近河堤桥塔承台施工中河堤防护方案设计

Protection Scheme Design for River Banks During Construction of Nearby Bridge Pylon Pile Cap

佛山市南海区东平水道特大桥主桥采用(35+260+51.5+66+62.5)m钢-混凝土混合主梁独塔斜拉桥,桥塔墩承台临近防洪大堤边坡,为保证承台施工过程中大堤的安全,对大堤防护进行方案设计。通过分析施工位置的地质条件、水位变化规律、大堤防护要求等,从安全性、施工便利性角度考虑,选用灌注桩+桩间高压旋喷桩止水的防护方案,防护桩直径1.25m,桩间距1.75m,横桥向设19根,顺桥向设7根,防护桩间采用2根0.6m高压旋喷桩形成止水帷幕,高压旋喷桩共50根。采用理正深基坑软件对防护桩桩身内力位移、地表沉降、嵌固稳定性、土的抗隆起稳定性进行计算,计算结果满足规范要求。工程实践证明,该方案确保了大堤和基坑的安全。

The main bridge of Dongping Waterway Bridge in the Nanhai District,Foshan City,is a single-pylon steel-concrete hybrid girder cable-stayed bridge with span arrangement of（35＋260＋51.5＋66＋62.5）m.The pile cap of the pylon pier is near the side slope of the river bank.To ensure the safety of the river banks during the pile cap construction,peculiar scheme design was performed.By analyzing the geological condition,water level variation and the protection requirements of the river banks at the bridge site,the scheme of bored piles plus the high-pressure jetting piles inserted among the bored piles for the sake of water stopping was selected,out of the concern of safety and construction convenience.The diameter of the protection piles is 1.25 m,spaced by 1.75 m.A number of 19 piles are erected along the transverse direction and 7 along the longitudinal direction.2,？0.6m high-pressure jetting piles are inserted among the piles to form water-stopping curtain.A number of 50 high-pressure jetting piles are inserted.The Lizheng deep foundation software was used to calculate the internal force and displacement of the pile shafts,ground settlement,embedding stability and the anti-upheaval stability of the soil.The calculated results meet the code requirements.The engineering practice proves that the scheme can assure the safety of the river banks and the foundation pit.