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泥皮的存在会使灌注桩承载力降低,由于受施工工艺、方法以及现场条件影响,泥皮并不全部分布于整个桩壁四周,而是存在于部分区域。用折减桩土接触面参数的方法来模拟泥皮作用,对不同高度分布的泥皮进行数值方法模拟,分析不同泥皮分布高度对灌注桩的承载性状影响。计算结果表明,泥皮分布高度越高,荷载-沉降曲线越陡,拐点位置不断前移,当泥皮性状比α=0.8时,极限承载力损失约在5%~25%,当α=0.6时,极限承载力损失约在5%~50%。泥皮分布高度对桩侧摩阻力的影响与上部荷载作用下泥皮性质能够提供的极限摩阻力有关;有泥皮存在的部位,桩身轴力传递速率明显加快,泥皮分布高度越高,桩身轴力传递速率越快,且越向下部,泥皮分布高度对轴力的影响越大;泥皮分布越高,桩侧摩阻力就越容易达到极限摩阻力,导致泥皮分布越高,桩端阻力越大。
The existence of mud skin will reduce the bearing capacity of cast-in-situ piles. Due to the influence of construction technology, methods and on-site conditions, the mud skin does not all distribute around the entire pile wall but exists in some areas. The method of reducing the contact surface between pile and soil was used to simulate the effect of the soil cover. The numerical simulation of the soil cover with different heights was carried out to analyze the influence of the distribution height of the soil cover on the bearing properties of the pile. The results show that the higher the height of mud distribution is, the steeper the load-settlement curve and the position of inflection point keep moving forward. When the trash ratio is α = 0.8, the ultimate bearing capacity loss is about 5% ~ 25% When the ultimate bearing capacity loss of about 5% to 50%. The influence of the height of the mud skin on the friction resistance of the pile is related to the ultimate frictional resistance that the mud skin can provide under the action of the upper load. The axial force transmission rate of the pile body is obviously accelerated in the presence of mud skin, The faster the axial force transmission of the pile, and the more the lower the height, the greater the influence of the height of the mud distribution on the axial force; the higher the distribution of the mud, the easier it will reach the ultimate friction, which will result in the higher distribution of the mud , The greater the pile end resistance.