桩基沉渣控制

东岳基建 DONGYUE INFRASTRUCTURE 1 本文所述沉渣是指砂沉淀及泥浆沉淀的结合物 桩孔孔壁坍塌 产生的沉淀物不包括在本文所述沉渣中 有关孔壁坍塌的防治内容 请见 塌孔专项防治措施 孔底沉渣控制专项措施孔底沉渣控制专项措施 The control measures of sediment in bottom of the hole 1 沉渣厚度超标产生的原因沉渣厚度超标产生的原因 The reasons why the thickness of sediment exceed the standard 在旋挖钻桩施工过程中 不可避免的会产生一些土壤颗粒沉淀 物及由于使用泥浆而产生的泥浆沉淀物 规范的施工流程和合理的 材料运用可以将沉渣的厚度保持在较低水平 导致桩的承载力无法 满足要求的沉渣产生的原因如下 It may produce some soil particles precipitate and mud sediment inevitably in the construction process of rotary drill pile The thickness of sediment can maintain at a lower level if the construction process and materials was reasonable The reasons why the thickness of sediment exceed the standard was as follow 1 泥浆配比不合理 东岳基建 DONGYUE INFRASTRUCTURE 2 Mud ratio is not reasonable 由于泥浆指标不好 造成了泥浆携渣能力差 很多岩块 岩粒 岩粉 泥坯不能携出钻孔 Because the mud index is not good so the mud can not carry the rock powder rock clay out of the drill 2 二次清孔不彻底 The second time hole cleaning is not thorough 在钢筋笼下放完毕后进行二次清孔 是一个关键的工序 也是 灌注混凝土前最后一次清理桩底沉渣的机会 但此时 清孔受到钢 筋笼直径较扩大头小的限制 加之导管直径较大 正循环时导管底 水流冲击力有限 孔底的岩块 岩粒 岩粉及泥坯清除不彻底 因 此 在终孔后若不认真清孔 二次清孔在本工程作用有限 无法达 到彻底清孔 The second time hole cleaning was after the installation of steel reinforcement cage It is a key process and is the last time to clean up the sediment of pile bottom before grout concrete but the hole cleaning was limited by the diameter of steel reinforcement cage and the diameter of catheter water flow impact pressure was not enough of positive cycle in duct bottom the rock rock powder and granular mud at bottom of the hole 东岳基建 DONGYUE INFRASTRUCTURE 3 can not be cleaned thoroughly Therefore The second time hole cleaning just has little effect in the hole cleaning it shall clean up the hole carefully after the end of the hole 3 沉渣量测有误差 如测绳伸缩 测量时测绳不垂直等 Sediment measurement has error such as measuring rope was extended the measuring rope is not vertical when measuring the sediment 4 施工人员操作失误 如二次清孔验收后 没有注意保护桩 口 导致土块掉入桩孔中 Construction worker s operation errors such as the second time hole cleaning after acceptance pay no attention to the protection of pile so clod fall into the hole 2 预防措施预防措施 Preventive measures 1 保证泥浆满灌 泥浆可以很好地保护孔壁 保持泥浆大致与水平地面在同一平 面 满灌的泥浆对孔壁具有水头压力 减少进入泥浆中的土壤颗粒 增强泥浆携带土渣的能力 Slurry can protect the hole wall well keep the mud level and the 东岳基建 DONGYUE INFRASTRUCTURE 4 ground at the same plane the filling of the mud has water head pressure on the hole wall reduce the soil particles into the slurry and enhance the ability of the mud carry soil out 2 二次清渣 第二次清孔是在下好钢筋笼和导管后进行 利用导管进行清孔 清孔后要保证沉渣 50mm 比重范围在 1 05 1 1 之间 含沙量 4 粘度为 18 21s 以便能将孔底周围虚土清除干净 最终沉渣达到设 计规范要求 The secondary hole cleaning was carried out after the reinforcement cage and the catheter in a good position use the catheter for hole cleaning and ensure that the sediment is equal to or less than 50mm after cleaning the hole specific gravity in the range of 1 05 1 1 the sediment concentration is equal to or less than 4 viscosity of 18 21s clean up the sediment around the bottom of the hole eventually meet the requirement of the standard 3 经常复核测绳的尺度是否精确 及时更换刻度不清晰 伸 缩量较大的测绳 check the measuring rope scale is accurate or not regularly replace the measuring rope witch scale is not clear and expansion is larger timely 东岳基建 DONGYUE INFRASTRUCTURE 5 4 向工人强调沉渣对桩承载力的危害及由此造成的严重后果 并将质量保证工作以书面的形式落实到相关责任人 Emphasize on the dangers of sediment on the pile to the workers and the quality assurance work should be charged by responsible person 5 注意保护验收后的桩口 严禁非工作人员靠近桩口 Protect the pile after acceptance non staff is allowed to come close to the pile 6 灌注过程中 适当加大首灌混凝土方量 选用大口径料斗 连续浇灌 增强对孔底沉渣的冲击力减少孔底沉渣的残余 In