PHC管桩动力特性试验研究

系统地阐述了竖向/水平-回转耦合强迫振动和扭转自由振动等动力特性测试的原理和计算方法,并对某新建火力发电厂PHC管桩进行了动力特性试验。试验分析计算所得的抗压刚度Kz、抗剪刚度Kx、抗弯刚度Kj、抗扭刚度Ky和竖向振动阻尼比zz、水平-回转耦合振动第1振型阻尼比zxj1、扭转振动阻尼比zy 离散性小,有很好的规律性。试验是在桩头自由条件下进行的,实际桩头嵌固在桩基承台中,增加了桩头的嵌固条件和承台侧面填土抗力的影响,故具体应用时可根据承台结构、承台侧面填土、承台底面与地基土接触等具体情况酌情予以提高。

Test study on dynamic properties of PHC pile

The parameters of foundation dynamic properties are the necessary data for analysis of dynamic response and stability of all constructions under dynamic loading. At present, prestressed high strength concrete piles(PHC) are applied broadly to civil engineering. The properties of PHC under static force have been studied much, but rarely under dynamic force. This paper expounds the principles and methods of dynamic properties tests as vertical forced vibration test, forced vibration coupled with translating and rocking test,twisting free vibration test,and three PHC piles of a thermal power plant to be built are measured by this dynamic properties test. The analyzed results show that compressing rigidity (Kz),shearing rigidity (Kx), bending rigidity (Kj), twisting rigidity(Ky), and some damping coefficients (zz , zxj1, zy) have little variety and good regularity. However,piles are usually constructed to form base slab,which increases lateral loading capacity of single pile, so the values of Kx , Kj , Ky , zxj1, zy should be properly increased according to the type and lateral fill of base slab, contact property between the lower face of base slab and subsoil.