砂土地基中受水流影响的竖向力-水平力联合受荷桩承载特性模型试验研究  

Model study on the bearing behavior of V-H combined loaded pile in sand considering the current effects

作　　者：邹新军[1,2] 曹雄 周长林 ZOU Xin-jun;CAO Xiong;ZHOU Chang-lin(College of Civil Engineering,Hunan University,Changsha,Hunan 410082,China;Key Laboratory of Building Safety and Energy Efficiency of 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》2020年第6期1855-1864,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51578231,No.51378197)。

摘　　要：海上风机大直径单桩基础除承受竖向荷载V与水平荷载H外,同时还受水流冲刷、扰动。基于Swipe加载法,在室内水槽模型中设计完成了砂土中的V-H联合受荷桩测试,获得了静、动水流状态及不同竖向力大小条件下的荷载-位移曲线及桩身弯矩分布;经无量纲化处理与拟合,得到了考虑水流影响的V-H联合受荷桩承载力包络线及其简化计算公式。结果表明:水流冲刷降低了总的桩侧摩阻力,导致竖向荷载-位移曲线初始刚度降低;桩身水平位移和弯矩在仅受水流作用时较小,但同时受水流、水平荷载作用相比于单一水平受力时则明显增大;增加桩顶竖向荷载在水平位移较小时有助于提高桩身水平承载力,但随水平位移增大且竖向荷载接近竖向极限承载力V_u时,可能会因重力二阶(P-Δ)效应而削弱桩身水平承载力;桩身最大弯矩位置不会随水流状态与竖向荷载大小的改变而明显变化,基本保持在泥面以下2~3倍桩径处。Large-diameter single pile foundations of offshore wind turbines are always subjected to complex scour and disturbance of currents,as well as the vertical load(V)and horizontal load(H).Based on the Swipe loading method,the test of V-H combined loaded piles in sand is designed and completed in flume.The load-displacement curves and the bending moment of the pile shaft under both static and flowing states with different vertical loads are obtained.By dimensionless processing and fitting,the envelope of the V-H combined bearing capacity with consideration of the current effects is obtained.The results show that the total friction resistance of the pile side decreases due to the scouring action caused by the currents,and thus leading to decrease in the initial stiffness of the vertical load-displacement curve.When merely subjecting to the currents,the horizontal displacement and bending moment of the pile shaft are relative small,but they show significant increments when simultaneously subjecting to the combined action of horizontal force and the currents.An increase in the vertical force V on the pile head helps to improve the horizontal bearing capacity of the pile when the horizontal displacement of the pile is small.But when the horizontal displacement is large and V approaches to the limitation of the vertical bearing capacity V_u,the horizontal bearing capacity of the pile will be decreased due to the second order effects of gravity(P-Δ).The position of the maximum bending moment of the pile shaft is not significant changed with the flow state and V,which generally appears at the locations of 2–3 times the pile diameter below the mud line.

关 键 词：大直径单桩 水流 V-H联合荷载 承载特性 模型试验 

分 类 号：TU473.1[建筑科学—结构工程]