越南海防热电厂二期工程超长大直径灌注桩荷载传递机理试验研究

Mechanism of Load Transfer on Ultra-long and Large-Diameter Bored Piles at Thermal Power Plant Phase-Ⅱ in Hai Phong City of Vietnam

越南海防热电厂二期工程位于海防市(Hai Phong)水源镇(Thuy-nguyen),装机容量为2×300 MW。场地为Gia河边的低地,属于喀斯特地貌区,岩溶比较发育,上部存在较厚的淤泥质土层,土质较差,不能满足厂区上部结构对地基的要求,因此厂区主要建筑物的地基处理采用钻孔灌注桩。对该工程区桩基进行了检测试验,依据桩基试验实测数据,分析了桩身轴力的荷载传递机理以及桩的荷载-沉降特性。结果表明:该工程区的单桩极限承载力可取为7 000 kN;桩身轴力的传递特性受多种因素影响,桩顶荷载主要通过桩侧摩阻力逐渐向下传递,具有明显的摩擦桩特点,桩侧摩阻力所占比重较大,而桩端阻力所占比重较小;桩底沉渣厚度显著影响桩顶沉降量与极限承载力。

The thermal power plant is located at Thuy-nguyen District,Haiphong city in Vietnam with an installed capacity of 2×300 MW.Since the power plant is located in a low land near the Gia River with developed karst geomorphology and thick mucky soil strata on the top,the soil quality is too weak to meet the requirements of the foundation.Bored piles are planned to be used on the main construction area.Pile foundation test is performed in this project area.Mechanism of axial force transfer on the pile and the characteristics of load-settlement of the pile are analyzed.The results suggest that the ultimate bearing capacity of single pile could be 7000kN in this area.The axial force transfer on pile is influenced by many factors.Load on the pile top is transferred down gradually by lateral friction resistance which takes up a great proportion compared with the friction resistance on the pile end.Sediment thickness at the bottom of pile remarkably affects the pile top settlement and the ultimate bearing capacity of pile.