饱和粉土地基低强度混凝土桩振动沉管及静载试验
Vibration Pipe Sinking and Static Load Test of Low-strength Concrete Pile in Saturated Silt Soil Foundation

为研究饱和粉土地基低强度混凝土桩振动沉管施工产生的超孔隙水压力分布、消散规律及单桩和复合地基的承载特性，对滨州市饱和粉土地基进行了低强度混凝土桩的振动沉管和静载试验。结果表明：沉管振动下沉时，最大超孔隙水压力一般出现在桩端以上2~3 m；沉管振动下沉对桩周土体的扰动较小，最大超孔隙水压力与上覆土有效应力的比值仅为0.327；单桩振动拔管后15 min，临近超孔隙水压力的消散率可达到65%~75%；与设计规范的估算值相比，振动沉管成桩后单桩竖向极限承载力偏小，仅为估算值的55%~60%；低强度混凝土桩的加固作用明显，复合地基承载力与天然地基相比提高了约1倍。
In order to study the distribution and dissipation law of excess pore water pressure produced during construction, the single pile and composite foundation load？？bearing characteristics in saturated silt soil foundation, vibration pipe sinking and static load test of low strength concrete pile were carried out in Binzhou City. The results show that when vibration pipe sinking, the maximum excess pore water pressure appears 2？？3 m above the end of pile； vibration pipe sinking disturbs the soil around the pile little, the maximum excess pore water pressure is only 0.327 of that of overlying soil effective stress; the dissipation rate of excess pore water pressure can reach 65%？？75% after extubation for fifteen minutes; compared with the estimate value of design norms, the single pile vertical ultimate bearing capacity of vibration pile sinking is only 55%？？60% of the estimate value; the low strength concrete pile reinforcement effect is obvious and the bearing capacity of composite foundation can increase by 1 time compared with that of natural foundation