摘要
研究目的:采用反射波法对冲击成孔单笼灌注桩进行桩身质量完整性检测,经验证发现在复杂地层中的灌注桩,存在严重扩径和露筋,既浪费大量混凝土,又影响桩身质量完整,为此须进行研究,找出其原因,改进其施工方法,达到既节约混凝土,又保证混凝土桩身质量完整。研究结论:(1)冲击成孔单笼灌注桩扩径原因是由于冲击成孔产生的冲击力,把地下水位以下的流砂、砾石、淤泥和与基岩面接触处的软塑黏土,以及溶洞内的充填物,分别冲击落入孔内,被泥浆返孔带出孔口,使其周围形成大于施工桩径的地下空间,灌注混凝土时地下空间处出现大的扩径,相应扩径的上方易出现缩径和露筋;(2)无地下水的硬塑粉质黏土地层可采用冲击成孔单笼灌注桩;(3)有地下水的流砂、砾石、淤泥等复杂地层可采用冲击成孔双笼灌注桩;能预防混凝土扩径和露筋,保证混凝土桩身质量完整;(4)在冲击成孔灌注桩的领域中应重视双笼法施工的应用与推广。
Research purposes ： Reflected wave method is used to investigate the integrity of the single cage pouring pile, validation found out there are serious expanding diameter and exposed reinforcement in the Complex Formation, both waste of concrete and the impact of the integrity of pile. Therefore should be studied, find out the reason, improved the construction method, not only can save concrete, but also ensure the concrete quality of pile body integrity. Research conclusions：（ 1 ） Impact hole single cage pile expanding diameter mainly due to the impact force to impact into the hole, put flow sand in underground water level, gravel, silt, and soft plastic clay layer contact the bedrock, as well as the cavities within the filling fabric impact into the hole, respectively by the mud return hole with a hole, which is larger than the diameter of pile formed around the construction of underground space, underground space concrete large expanding diameter, the corresponding expanding appear above the necking and exposed reinforcement; （2） Impact hole single cage pile can be made in hard plastie silty clay layer that have not groundwater; （3） Percussion hole double cage pouring pile construction should be used in order to prevention of expanding diameter and expose reinforcement of the concrete and ensure the concrete quality of pile body integrity in the sand, gravel, silt flow layer that have groundwater; （4） Percussion hole double cage pouring pile should be applied and generalized in the field of percussion hole pouring pile.
出处
《铁道工程学报》
EI
北大核心
2013年第12期19-22,共4页
Journal of Railway Engineering Society
关键词
灌注桩
冲击力
复杂地层
扩径
露筋
双笼
pouring pile
impact force
complex formation
expanding diameter
exposed reinforcement
double cage
