PHC刚性管桩基础上的闸首底板内力计算方法

Calculation method for internal force of soleplate of lock head on PHC rigid tubular pile foundation

为了合理解决复合桩基上的闸首底板内力简化计算问题,分析复合桩基沉降机理,基于应力与沉降分解法给出桩与桩、桩与土、土与桩和土与土的沉陷系数计算式,结合并列铰接地基梁法建立考虑桩-土-结构共同作用的计算模型。依托高石碑船闸工程实例,通过与查表法的对比验证计算程序的可靠性,研究在不同工况时底板单宽弯矩、沉降、地基反力的变化规律。结果表明,该模型计算的桩土分担比与有限元分析结果接近,计算精度可以满足结构简化分析的需要,能合理反映基桩的根数、以及间距与桩长不规则等因素对底板沉降和内力的影响。运营期相对于完建期而言,地基均处于回弹状态、底板弯矩增量有正负值,可优化调整底板宽缝封闭前边墩浇筑高程、回填土高程,使得运营期出现的正负弯矩接近相等。

In order to solve the problem about simplified calculation of the internal force of soleplate on composite pile foundation, the settlement mechanism of composite pile foundation was analyzed. The formula of settlement coefficients of pile and pile, pile and soil, soil and pile, soil and soil was given based on stress and settlement decomposition method, combining with the method of the spatial foundation beam hinged side-by-side, and the calculation model that considering the interaction in pile, soil and structure was established. On the basis of the Gaoshibei Ship Lock, the reliability of computational procedure was verified by comparing with table method, and the variation law of soleplate＇ s bending moment per unit width, settlement and subgrade reaction was researched in different conditions. The results show that, the sharing ratio of pile and soil calculated by this model is close to the result calculated by FEM, and the calculating precision can meet the requirements of simplified structural analysis. The model can reasonably reflect the influence of pile＇s quantity, irregular interval and length on the settlement and internal force of soleplate. In terms of operating period relative to the end of construction, the foundation is in rebound state, the increment of soleplate＇s bending moment have positive and negative value. The pouring elevation of side pier and the filling elevation of backfill soil should be optimized before joints of soleplate, which is sealed to make the positive and negative bending moment approximately equal in operating period.