Research On Key Construction Technology Of Afloat Large Diameter Drilled Pile With Large Tidal Range And Complex Geology

Pingtan strait Road-rail bridge(B0 ~ B58)is the first road-rail Sea crossing bridge in china.The bridge are very bad environment,big wind,high wave,deep water,rapid flow,large tidal range,complex geological conditions.The construction technology is complex and difficult.The lower foundation part of bridge use the large diameter drilling bored pile,which is 3.0 m in diameter and 5.23 ~ 15 m the socket depth.Pile foundation construction impact drill reverse circulation method into a hole.Due to the complexity of geological conditions of bridge site location: rock slope,uneven coating thickness,high strength boulder(mostly tuff),steel liners in the difficult,and because the sea one day two,maximum tidal range of 7 m,cause the breast wall mud and external pressure difference very difficult to control water and soil,mud leakage arising in the course of drilling pile construction and even collapse hole problem,seriously affected the construction speed and efficiency.It is to solute the problems of large diameter bored piles in slurry leakage,hole collapse,hard and soft rock strata drilling in Pingtan strait Road-rail bridge(B0 ~ B58),use the theoretical analysis,numerical simulation and field test method.By studying the damage forms of seepage failure occurs and leak slurry,summarizing the construction technological process of the high-pressure rotary jet grouting piles and the water-stopping curtain fill flaky + clay(cement)box method,processing of inclined borehole drilling hard and soft rock backfill flaky method,and get all kinds of theoretical calculation formula of quantities.The research guides the large diameter bored piles construction of Pingtan strait Road-rail bridge(B0 ~ B58),and improve the construction efficiency,The achievement have important reference value for construction in marine engineering.