| 摘要: |
| 钻井船插桩时会使邻近平台桩桩身受到挤土荷载作用，这种挤土荷载可能会严重影响平台桩的承载能力。采用CEL方法结合模型试验分析桩靴贯入砂土层时邻近桩受到的挤土压力变化。通过对缩尺试验结果的计算，验证了CEL方法的可行性。进一步分析了桩靴贯入砂土层时，邻近桩桩身挤土压力的变化。分析结果表明，邻近桩靠近桩靴一面受到的挤土压力随桩土相对位移的增加而不断增大直到极限值，在泥面以下10倍邻近桩桩径范围内，桩身最大挤土压力随土层深度逐渐增加，其变化范围为1.5~5.0倍的朗肯被动土压力，当土层深度超过10倍邻近桩桩径后，桩身最大挤土压力趋于稳定，约5.0倍的朗肯被动土压力；而远离桩靴一面受到的挤土压力随相对位移增加而不断减小，最终保持在朗肯被动土压力的10％～20％；桩身受到的挤土压力合力随桩土相对位移增加而不断增大直到极限值，在泥面以下10倍邻近桩桩径范围内，桩身极限挤土压力合力随土层深度逐渐增加，其变化范围为1.5~5.0倍的朗肯被动土压力；当土层深度超过10倍邻近桩桩径后，桩身极限挤土压力合力趋于稳定，约5.0倍的朗肯被动土压力。最后还定量分析了砂土摩擦角、弹性模量、泊松比和净间距的变化对插桩挤土力变化关系的影响。 |
| 关键词: 挤土力 CEL方法 极限土压力 p－y曲线 钻井船插桩 |
| DOI：10.12170/201905012 |
| 分类号:TU473 |
| 基金项目:国家自然科学基金资助项目（51579174） |
|
| Analysis of pile shaft soil pressure caused by spudcan penetration into sand |
|
GUO Dong1,2, WANG Jianhua1,2, FAN Yifei1,2
|
|
1.State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin;2.Geotechnical Engineering Institute, Tianjin University, Tianjin
|
| Abstract: |
| The spudcan penetration can give large soil compaction loads on the pile foundation adjacent to the platform, which may seriously affect the bearing capacity of the platform pile. Based on available model tests, the CEL method is adopted to investigate the variation of soil resistance along the pile shaft during the spudcan penetration into sand. The efficacy of the method is proved by comparison with a 1g model test. On this basis, some analyses of the relationships between the soil-pile relative displacement and the soil pressure are carried out in this paper. The analysis results show that the soil squeezing pressure facing towards the pile shoe increases with the increase of the relative displacement of pile and soil until the limit value. Within the range of 10 times of the adjacent pile diameter below the mud surface, the maximum soil squeezing pressure of the pile shaft gradually increases with the depth of the soil layer, and the range of change is (1.5~5.0) Kpγ′z; and when the soil depth is more than 10 times of the pile diameter, the maximum earth pressure of the pile shaft tends to be stable, which is about 5.0Kpγ′z. The soil squeezing pressure on the side far from the pile shoe decreases with the increase of the relative displacement, and finally keeps at (0.1~0.2) Kpγ′z. The resultant force of soil squeezing pressure on the pile shaft increases with the increase of the relative displacement of pile and soil until the limit. Within the range of 10 times of the adjacent pile diameter below the mud surface, the ultimate soil pressure resultant force of the pile increases gradually with the depth of the soil layer, and the range of change is (1.5~5.0) Kpγ′z. When the soil depth is more than 10 times of the pile diameter, the ultimate earth pressure resultant force of the pile shaft tends to be stable, which is about 5.0Kpγ′z. Finally, the influences of the changes in sand friction angle, elastic modulus, Poisson ratio of sand and net spacing on the change of the soil squeezing pressure are quantitatively analyzed. |
| Key words: soil pressure CEL method ultimate soil pressure p-y curves spudcan penetration |
