静压有孔管桩超孔隙水压力消散的影响因素分析

Influencing Factors Analysis on the Dissipation of Excess Pore Water Pressure of Static Perforated Pipe-pile

静压管桩因其质量可靠和施工过程中具有无噪声、无振动、应力小等诸多优点被广泛用于工程中。但静压管桩属于部分挤土桩,在沉桩过程中,桩周土体不仅会产生较大位移,而且会在短时间内形成较高的水压力。有孔管桩通过在桩身开孔能使土中自由水流入管腔,从而减小局部土体位移,加速超孔隙水压力的消散并降低其最大值。本文利用圆孔扩张理论,通过理论公式和工程算例的对比分析,得出有孔管桩沉桩超孔隙水压力随径向距离的增大呈对数衰减,随沉桩速率的加快不断增大,随深度的加深呈递增趋势,随开孔孔径的加大逐渐减小。可对控制管桩挤土效应提供可靠的理论依据。

Static pressure pipe-pile is widely used because of its reliable quality,noiseless and vibration-less characteristics,less construction stress and so on.But static pressure pipe pile belongs to partial squeezing soil pile,and the squeezing effect produced during pile sinking will not only produce huge disturbance to the soil around the pile,but also produce huge excess pore water pressure in a short time.The pipe-pile with holes can make the free water flow into the inner cavity of the pipe to reduce the displacement of soil,thus reducing the maximum value of excess pore water pressure and accelerating the dissipation of excess pore water pressure.In this paper,using the theory of cavity expansion,through the comparison of theoretical formula and an example,it shows that the excess pore water pressure decreases with the increase of radial distance;the excess pore water pressure increases with the increase of the velocity;the excess pore water pressure increases with depth deepening;the excess pore water pressure decreases with the increase of pore size.Thereby it can provide a reliable theoretical basis for controlling the soil compaction effects.