The Tiansheng Port special ship channel bridge of the Hutong Changjiang River Bridge is a flexible arch bridge with three-span continuous rigid girder with span arrangement (140+336+140) m .The main pier No .4 of the bridge is located in the riverbed area of deep silty sand stratum in the Changjiang River and the foundation for the pier has 36 nos .of φ2 .5 m bored piles that are 115 m long and are bored to the depth of 121 .5 m .In the light of the characteristics that the stratum succession at the foundation is complex ,the phase changes are drastic and the silty sand stratum is deep ,the construction of the bored piles of the pier was carried out ,using the bor-ing platform .The holes of the piles were bored ,using the high-power air lifting reverse circulating boring machine and the high-quality PHP slurry .The reinforcement cages for the piles were manu-factured by the long line match method and were lowered in sections into the holes after the holes were well bored and cleared off for the first time by the air lifting reverse circulating .At this stage ,the holes were cleared off again for the second time ,the holes were inspected and the tremie concrete for the piles was cast by the tremie duct method .The ultrasonic inspection and the hole depth measurement data of the bored piles of the pier after the construction showed that the diame-ters and inclination degrees of the bored holes and the sediment thickness of the second time clear-ing all met the special quality inspection and evaluation criteria of the project and the pile shafts also met the standard of Class I piles .%沪通长江大桥天生港专用航道桥为(140+ 336+140 ) m的三跨连续刚性梁柔性拱桥 ,该桥4号主墩位于长江深厚粉砂层河床区 ,采用36根φ2 .5 m钻孔桩基础 ,桩长115 m ,钻孔深度为121 .5 m.针对4号主墩基础地层层序复杂、相变剧烈、厚度较大的特点 ,4号主墩钻孔桩采用钻孔平台方案施工 ,并采用大功率气举反循环钻机配合优质PHP泥浆进行钻孔 ,钢筋笼采用长线法制作 ,钻孔桩成孔后 ,采用气举反循环工艺进行第1次清孔,清孔后分节下放钢筋笼 ,进行第2次清孔 ,清孔合格后 ,采用导管法进行桩基水下混凝土灌注施工.4号主墩钻孔桩施工后,根据超声波检测及孔深数据测量 ,其桩孔孔径、孔斜及二清沉渣厚度均达到工程专项质量检验评定的标准 ,桩身均达到Ⅰ类桩的标准.
展开▼
