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Model tests on effects of spudcan penetration on an adjacent pile group
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摘要: 为研究钻井船作业过程中桩靴贯入对邻近群桩的影响，在砂土层中开展了1g条件下的1×2型群桩模型试验，邻近桩桩头条件为固定桩头，桩间距为2.5倍桩径。通过对桩靴贯入土层前和桩靴贯入土层过程中邻近群桩中近桩靴桩的弯矩的测量，得出沿桩身弯矩随桩靴贯入土层深度的变化规律，并与相同净间距单桩桩身响应情况对比。将同一时刻群桩桩身最大弯矩相对于单桩桩身最大弯矩的增长率定义为弯矩增大系数，通过弯矩增大系数的变化研究插桩对邻近群桩效应的影响及插桩对邻近群桩效应的影响随净间距的变化。研究表明：与桩靴贯入土层前相比，桩靴的贯入使邻近群桩效应减弱，且随着净间距的增加，插桩对邻近群桩效应的影响越来越小，净间距超过1倍桩靴最大直径时，建议可以不考虑插桩对邻近群桩的影响。Abstract: A series of model tests in sand under 1g condition were conducted to investigate the influence of spudcan penetration on an adjacent pile group. Behaviors of piles with fixed pile head constraints were observed, and the pile spacing was selected as 2.5 times the pile diameter during the tests. The changing pattern of the pile shaft bending moment with spudcan penetration into the soil was analyzed by comparison of the maximum bending moment along the pile near the spudcan in the adjacent pile groups before and after spudcan penetration, and the response of a single pile with the same clearance was compared as well. The growth rate of the maximum bending moment of the pile group relative to the maximum bending moment of the single pile body was defined at the same time as the flexural strength ratio. The influence of spudcan penetration on pile group effect and the influence of clearance on the pile group effect were studied through the flexural strength ratio. Compared with the pile group effect before spudcan penetration, it is indicated that spudcan penetration weakens the pile group effect; and the influence of spudcan penetration on the pile group effect is weakened with the increase of clearance, when the clearance exceeds one time the maximum spudcan diameter. It is recommended that the influence of spudcan penetration on the adjacent pile group can be ignored. This study can provide useful guidance to investigate the influence of spudcan penetration on an adjacent pile group.
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Key words:
- model test /
- spudcan /
- sand site /
- clear spacing /
- pile group effect
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图 10 桩靴贯入土层时的桩身弯矩
Figure 10. Pile bending moments when spudcan penetrates into soil layer
表 1 桩身最大弯矩
Table 1. Maximum bending moment of the pile
dp/D T1 T2 T3 单桩/（N·m） 群桩/（N·m） $ {\eta _{\rm{M}} } $ /%单桩/（N·m） 群桩/（N·m） $ {\eta _{\rm{M} } } $ /%单桩/（N·m） 群桩/（N·m） $ {\eta _{\rm{M}} } $ /%0.5 9.35 7.93 −15.2 8.53 7.32 −14.2 5.67 6.04 6.5 1.0 9.71 8.13 −16.3 8.12 6.83 −15.9 5.80 6.07 4.7 1.5 10.04 9.07 −9.7 4.37 4.53 3.7 6.28 6.39 1.8 2.0 12.69 10.08 −20.6 6.83 5.57 −4.4 6.40 6.75 5.5 
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