苑举卫1,孙邦宾2,郭 彤3,姚 兵2
预应力管桩用于基坑支护的抗弯刚度分析及工程应用研究
苑举卫1,孙邦宾2,郭 彤3,姚 兵2
摘 要:预应力管桩水泥土复合挡墙支护技术(简称PCMW工法)采用PHC管桩作为挡土构件,其抗弯刚度的合理选取对设计结果和支护安全影响较大。本文引入刚度降低系数,通过开展PHC管桩和钻孔桩的抗弯刚度对比分析研究,建立了面向设计的PHC管桩抗弯刚度和弯矩取值原则;结合工程实例,验证了PHC管桩抗弯刚度计算方法的适用性。研究结果表明:由于预应力的存在,使得预应力管桩开裂后的刚度衰减速度远低于钻孔灌注桩;采用本文推荐的PHC管桩抗弯刚度方法得到的计算结果与基坑监测结果规律性吻合良好。
Abstract: In PCMW (Prestressed Concrete Tube-pile Soil-cement Mixed Wall), the precast tube-pile is used to withstand soil pressure, whose bending stiffness has great influence on design of supporting structure in deep excavation and deformation predication. Based on analysis of stiffness reduction coefficient between PHC pile and cast-in-place concrete pile, the result shows that prestress makes PHC pile keep relatively higher bending stiffness after cracking, which benefits for lateral deformation control of foundation pit. A successful project example of PHC pile with PCMW demonstrates the applicability of the method.
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