【作者】 李鹏； 王殿斌； 孟庆洲； 冷传旭； 吴刚； 向明；

【Author】 LI Peng;WANG Dianbin;MENG Qingzhou;LENG Chuanxu;WU Gang;XIANG Ming;Qingdao Surveying & Mapping Institute;Qingdao Innovation Center of Smart (Green) Geotechnical Technology;

【机构】 青岛市勘察测绘研究院； 青岛市智慧(绿色)岩土技术创新中心；

【摘要】 以泥岩为持力层的锤击施工预制桩常出现承载力不足、沉降值过大现象,其承载破坏原因尚无统一认识。本文通过钻探及原位测试、现场检测、土工试验和扫描电镜试验等手段,对预制桩端的泥岩结构变化进行研究,探讨预制桩破坏的机理。研究表明:泥岩持力层锤击施工预制桩的承载破坏与锤击贯入有直接关联,桩端岩体孔隙发生重组,孔隙重组程度、裂隙大小与锤击贯入强度有关,同样条件下锤重较大或锤击数较多时,预制桩承载破坏的概率越大。泥岩的矿物成分和沉积韵律是影响预制桩承载力的重要因素,桩端岩体黏土矿物含量较高时,岩体强度相对较低,预制桩承载力越低。桩端持力层破坏与泥岩遇水膨胀软化效应无关联,地下水不是预制桩承载破坏的直接诱因。更多还原

【Abstract】 The phenomenon of inadequate load-bearing capacity and excessive settlement often occurs in the hammer-driven prefabricated piles with mudstone as the bearing layer, and a consensus regarding the underlying causes of pile bearing failure has not been established. Through drilling, in-situ testing, geotechnical testing, and scanning electron microscopy techniques, this study investigates the structural changes of mudstone at the bottom of prefabricated piles and discusses the failure mechanism associated with these piles. The findings demonstrate a direct correlation between the failure of hammer-driven prefabricated pile and hammer penetration. Pore reorganization occurs within the rock mass at the bottom of piles, with the extent of pore reorganization and crack size being influenced by the strength of hammer penetration. Under identical conditions, an increase in either hammer weight or number of strikes amplifies the likelihood of prefabricated piles failure. The mineral composition and deposition rhythm of mudstone are important factors that influence the load-bearing capacity of prefabricated piles. When the clay mineral content is high, it results in relatively lower strength of the rock mass, thereby leading to a reduced bearing capacity of prefabricated piles. The failure of the bearing layer is not attributed to the softening effect caused by mudstone expansion upon exposure to water,and it can be concluded that groundwater does not directly contribute to the failure of prefabricated pile bearing.更多还原