塑料套管混凝土桩单桩承载特性研究

Research on Bearing Performance of Plastic Tube Cast-in-place Single-pile

为研究塑料套管混凝土桩(TC桩)的承载特性,采用室内试验研究外设塑料套管对桩体竖向抗压强度的影响;结合现场试验,对不同桩尖类型的桩体进行了静载和荷载传递试验,分析不同桩尖类型的TC桩单桩承载能力和桩身轴力、侧摩阻力及端阻力的变化规律。建立了TC桩单桩沉降和侧摩阻力的简化计算方法,并与现场实测数据进行了对比。试验结果和理论分析结果表明:外设的塑料套管可提高桩身混凝土的竖向抗压强度约23%～38%;桩尖直径为26cm圆形桩尖的单桩静载试验的极限承载力最大,其次是30cm圆形桩尖、方形桩尖、十字形桩尖;侧摩阻力沿桩深呈两头小中间大的态势,最大侧摩阻力发生在2/5～4/5桩深范围内;所得的理论值与实测值相吻合。

In order to investigate the bearing properties of the plastic tube cast-in-place concrete pile （TC pile）, the vertical compressive strength of the pile was studied at lab. Based on the field test, the static load test of single TC pile and load transfer experiment were carried out on the piles with different types of pile tips. And the bearing capacity of single TC pile was analyzed. The steel stress meters were buried in the pile body with circular pile tip of 26 cm in diameter and the frequency variation of steel stress meter was read during the process of static load test. The change laws of shaft force, skin friction and tip resistance were explored. The simplified calculation methods of settlement and skin friction for TC piles were established. Test results and theoretical analysis show that the external plastic tube can increase the vertical compressive bearing capacity of pile concrete by 23 %-38%; the ultimate bearing capacity of single pile with circular pile tip of 26 cm in diameter is maximum, followed by the pile with circular pile tip of 30 cm in diameter, pile with square pile tip and pile with cross pile tip; the skin friction is little atboth ends and large in middle, and the summit is within 2/5-4/5 pile length;the theoretical values are consistent with the measured.