斜坡桩水平循环特性模型试验及有限杆单元解  

Model test and finite beam element solution of cyclic lateral characteristics of piles in sloping ground

作　　者：彭文哲 赵明华[1,2] 杨超炜 赵衡[1,2] PENG Wen-zhe;ZHAO Ming-hua;YANG Chao-wei;ZHAO Heng(College of Civil Engineering,Hunan University,Changsha,Hunan 410082,China;Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education,Hunan University,Changsha,Hunan 410082,China)

机构地区：[1]湖南大学土木工程学院,湖南长沙410082 [2]湖南大学建筑安全与节能教育部重点实验室,湖南长沙410082

出　　处：《岩土力学》2023年第2期381-391,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.52108317,No.51908208)。

摘　　要：为了揭示斜坡效应和循环弱化效应共同影响下的斜坡桩水平循环特性,进行了不同循环次数、荷载幅值及坡度下的单向水平循环加载试验,并将水平静载试验作为对照,揭示了桩顶位移、桩身弯矩及地基反力等变化规律。综合考虑二阶效应及桩-土相互作用的影响,对单元刚度矩阵进行了改进,提出了有限杆单元解。将理论预测曲线等与实测曲线及幂级数法计算结果进行了对比,验证了有限杆单元解的合理性。结果表明:桩身弯矩及位移均随循环次数非线性增加,最大弯矩位置逐渐从无量纲深度z_(α)=1.25下移到z_(α)=1.75;桩顶无量纲位移y_(0,α)与循环次数n之间的关系符合幂函数y_(0,α)=An^(0.11);当荷载幅值由20 N增加到40 N时,最大无量纲弯矩由0.010增加到0.029,位置均保持在z_(α)=1.7附近;当坡度由30°增加到60°时,最大无量纲弯矩由0.011(z_(α)=1)增加到0.025(z_(α)=2.5)。To reveal the cyclic lateral characteristics of piles in sloping ground under the combined influence of slope effect and cyclic weakening effect,one-way cyclic lateral loading tests with different cycle numbers,load amplitudes and slope angles were carried out,and corresponding lateral static loading tests were conducted as a comparison.The variation trends of pile head deflection,bending moment and subgrade reaction were revealed.Then,the element stiffness matrix was improved by considering the second-order effect and pile-soil interaction to develop the finite beam element solution.Finally,the theoretical predicted curves were compared with measured curves and results calculated by the power series method to validate the finite beam element solution.The results show that the bending moments and pile deflections nonlinearly increase with cycle numbers,and the location of maximum bending moments gradually drops downwards from the non-dimensional depth z_(α)=1.25 to z_(α)=1.75.The relationship between the non-dimensional deflection y_(0,α)atop the pile and cycle number n satisfies the power function y_(0,α)=An^(0.11).When the load amplitude increases from 20 N to 40 N,the maximum non-dimensional bending moment increases from 0.010 to 0.029,but their locations remain near z_(α)=1.7.When the slope angle increases from 30° to 60°,the maximum non-dimensional bending moment increases from 0.011(z_(α)=1)to 0.025(z_(α)=2.5).

关 键 词：桥梁工程 桩基础 水平循环特性 模型试验 斜坡效应 有限杆单元法 

分 类 号：U473.1[机械工程—车辆工程]