RESEARCH ON MECHANISM OF JACK-UP DRILLING PLATFORM SPUDCAN PENETRATING INTO SATURATED SAND
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摘要: 为研究桩靴贯入饱和砂土的承载机制以及桩靴周围砂土变形机理，开展桩靴的抗压承载土工模型试验以及桩靴-土体相互作用的透明土试验，测得了桩靴荷载-沉降变化规律、桩靴周围砂土的位移向量场和等值线图，初步探讨了桩靴贯入饱和砂土时的承载机制与桩靴周围砂土变形机理。基于圆孔扩张理论及分段位移迭代算法，推导出静载作用下桩靴荷载-沉降变化规律；与试验结果的对比发现：计算误差约为11.7%。通过浅应变路径法(SSPM)计算得到桩靴周围土体位移理论值；与试验结果对比发现：计算误差在16.7%~26.3%。Abstract: In order to study the bearing characteristics of spudcan and the deformation mechanism of sand around the spudcan when the spudcan penetrated into saturated sand, model tests of bearing capacity of spudcan as well as transparent soil experiments of spudcan-soil interaction were carried out. The load-settlement curves of spudcan, displacement vector field and contour map of sand around the spudcan were obtained. According to the cavity expansion theory and segmental displacement iterative algorithm, the load-settlement curves of spudcan under static load was also derived, the error of which was about 11.7% compared with the test results. The theoretical displacement of soil around the spudcan was calculated using the shallow strain path method (SSPM). Compared with the test results, it is found that the calculation error was between 16.7% and 26.3%.
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Key words:
- spudcan /
- model test /
- transparent soil experiment /
- bearing mechanism /
- SSPM
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图 6 桩靴透明土模型示意图
Figure 6. Schematic diagram of spudcan model experiment in transparent soil
图 11 各级荷载作用下桩端阻力占桩顶荷载的比例
Figure 11. Ratio of pile end resistance to pile top load under various loads
图 12 桩靴贯入密实砂(相对密实度为0.821)的位移向量图
Figure 12. Displacement vector diagram of supdcan penetrating dense sand (relative compaction is 0.821)
图 13 桩靴贯入密实砂(相对密实度为0.930)的位移向量图
Figure 13. Displacement vector diagram of supdcan penetrating dense sand (relative compaction is 0.930)
图 14 桩靴贯入中密砂(相对密实度为0.665)的位移向量图
Figure 14. Displacement vector diagram of supdcan penetrating medium dense sand (relative compaction is 0.665)
图 15 桩靴贯入松散砂(相对密实度为0.231)的位移向量图
Figure 15. Displacement vector diagram of supdcan penetrating loose sand (relative compaction is 0.231)
图 16 桩靴贯入密实砂至2.1R时水平位移归一化等值线
Figure 16. Normalized contour of horizontal displacement of spudcan penetrating dense sand to 2.1R
图 17 桩靴贯入中密砂至2.1R时水平位移归一化等值线
Figure 17. Normalized contour of horizontal displacement of spudcan penetrating medium dense sand to 2.1R
图 18 桩靴贯入松散砂至2.1R时水平位移归一化等值线
Figure 18. Normalized contour of horizontal displacement of spudcan penetrating loose dense sand to 2.1R
图 19 圆孔扩张示意图
注：$ {r_0} $为桩体半径；$ {r_{\text{u}}} $为圆孔扩张半径； $ {\sigma _r} $为法向应力；$ {\sigma _\theta } $为切向应力。
Figure 19. Schematic diagram of cavity expansion
图 20 加压时桩靴-土体位移示意图
注：$ {r_0} $为桩身半径；$ {r_1} $为桩靴最大半径；$ \alpha $为桩靴半桩尖角；$ {S_1} $为桩侧土体扩张水平位移；$ {S_2} $为竖直位移。
Figure 20. Schematic diagram of spudcan displacement under pressure
图 24 荷载沉降曲线实测值与理论值对比
Figure 24. Comparison between measured and theoretical load-settlement curve
图 25 桩靴贯入至2.1R时各深度的水平向位移
Figure 25. Horizontal displacement at different depth caused by spudcan penetration to 2.1R
表 1 砂土土性参数
Table 1. Parameters of sand
密度/(kg·m−3) 最小干密度/(kg·m−3) 最大干密度/(kg·m−3) 含水率/(%) 相对密实度 泊松比 弹性模量/(MPa) 摩擦角/(°) 1.441 1.311 1.778 28.02 0.323 0.3 0.2 15 
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表 2 模型试验工况
Table 2. Model test conditions
试验编号 土样相对密实度 贯入深度记录点 T1 0.930 1.3R 2.1R T2 0.821 1.3R 2.1R T3 0.665 1.3R 2.1R T4 0.231 1.3R 2.1R
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