透水性混凝土桩施工中超孔隙水压力变化特性试验

Experiment on Variation Characteristics of Excess Pore Water Pressure During Pervious Concrete Pile Construction

为研究透水性混凝土桩施工中产生的超孔隙水压力的变化规律,通过在现场埋设孔隙水压力计的方法,监测并分析了振动沉管法单桩施工过程中及施工后桩周土体的超孔隙水压力随时间、径向距离及深度的变化,并根据监测结果分析了透水性混凝土桩单桩施工对桩周地基的影响。结果表明:对于高地下水位的粉性土地基,桩周土体的超孔隙水压力在沉管结束时达到最大值,之后消散速率较快,完全消散时间较短,且距桩越近,超孔隙水压力的上升与消散速率越快;超孔隙水压力在径向上与深度上大致呈现递减趋势,距桩越近,超孔隙水压力越大;地基土体的液化范围与加固范围的空间分布呈上大下小的漏斗形。提出的适用于透水性混凝土桩的施工工艺可为类似工程的设计与施工提供参考。

In order to reveal change regulation of excess pore water pressure during pervious concrete pile construction,excess pore water pressure of soil around the pile changing with time,radial distance and depth were monitored and analyzed during and after single pervious concrete pile construction by vibrating sinking pipe through the method of burying pore water pressure gauges in the field,and the effect of single pervious concrete pile construction on foundation around the pile was analyzed according to the monitoring results.The results show that excess pore water pressure of soil around the pile reaches maximum after sinking pipe and afterwards dissipates quickly for silt foundation with high groundwater level.The time of excess pore water pressure disappearing completely is very short.The rates of rise and decrease of excess pore water pressure are faster where it is closer to the pile.The excess pore pressure decreases approximately in radial direction and depth.The excess pore water pressure at same depth of each moment is larger where it is closer to the pile.The spatial distributions of liquefaction scope and reinforcement scope are about a funnel shape.The proposed construction technology suitable for pervious concrete pile can provide reference for design and construction of similar engineering.