双壁静压开口管桩贯入及承载特性试验研究

为了更进一步研究黏性土地基上静压桩贯入及承载特性,通过在桩身安装光纤光栅(FBG)以及在桩顶安装温度自补偿传感器,对双壁开口模型管桩的沉桩和单桩承载特性进行研究。结果表明:压桩力、桩端阻力、桩侧摩阻力随着贯入深度的增加而增大,且桩端阻力为沉桩过程的主要阻力,沉桩结束时占比为66.7%。相比于外管,内管桩侧摩阻力和桩身轴力均较小。荷载-位移曲线为陡降型,最大沉降为47.72 mm,极限荷载为6.3 kN,是沉桩终压力的2.48倍。试桩内管桩身轴力在土塞高度范围内以及外管桩身轴力在桩长范围内随着桩身埋深逐渐减小。内管桩侧摩阻力仅在土塞高度的范围内随着深度逐渐增加;外管桩侧摩阻力在荷载小于7.0 kN时,随着深度呈先增大后减小的趋势,当桩顶荷载达到7.0 kN时,随着深度逐渐增大。在各级荷载作用下桩端阻力占桩顶荷载的比例为53.6%～65.1%,表现出了较好的端承桩性状。研究结果对双壁开口管桩内外管贯入及承载特性的研究具有重要的意义。

Experimental study on penetration and bearing characteristics of double-walled static pressure open tubular pile

In order to further study the penetration and bearing characteristics of static pressure piles on cohesive soil foundation. In this paper, the pile-sinking and bearing characteristics of the double-walled open model pipe piles are studied by installing fiber grating (FBG) on the pile body and installing the temperature self-compensation sensor on the pile top. The results show that the pile driving force, the pile end resistance and the pile side friction resistance increase with the increase of the filling depth, and the pile end resistance is the main resistance of the pile sinking process, and the proportion at the end of the pile sinking is 66.7%. Compared with the outer tube, the inner tube pile side friction resistance and the pile axial force are small. The Q-s curve is steeply descending, with a maximum settlement of 47.72 mm and a limit load of 6.3 kN, which is 2.48 times the final pile pressure.. The axial force of the inner pile within the height range of the soil plug and the outer pile body within the length of the pile are gradually reduced with the depth of the pile. When the load is less than 7.0 kN, the lateral friction resistance of the outer pipe pile increases first and then decreases with the depth. When the pile top load reaches 7.0 kN, the lateral friction resistance of the outer pile increases with the depth.Under the load of all levels, the ratio of pile end resistance to pile top load is between 53.6 and 65.1%, showing a good end bearing pile behavior. Comparing the test results with the field test, the similarities and differences of the bearing characteristics of the prefabricated piles in the indoor and field tests are obtained, which is of great significance to the actual project.