摘要
变电站设备的正常运行,对地基沉降、差异沉降要求很高。某500 kV变电站位于围海滩涂,工程性质极差,天然地基不能满足变形及强度要求。桩网复合地基通过变形协调,能较充分地利用桩体承载能力,减小沉降及差异沉降,提高地基承载力和稳定性,是一种有效的软土地基处理技术。经方案比选与计算分析,该工程采用PHC-AB500桩网复合地基,桩中心距3 m,托板尺寸1.8 m×1.8 m,托板顶面铺设两层土工格栅,采用适合沿海滩涂地区的施工工艺。工程实施过程中,对桩网复合地基进行持续现场测试。测试结果表明,实测荷载分担比和地基沉降与计算值较为接近,荷载分担比逐渐稳定在70%~80%范围,大部分沉降发生在填筑施工期内;静载荷试验表明,桩网复合地基承载力满足设计要求;随着桩间土沉降,格栅逐渐发挥作用,第二层格栅变形和受力均比第一层格栅大。
There are high requirements on the foundation settlement and differential settlement for the substation equipment in the normal operation.A 500 kV substation is constructed in mud flat with extremely soft ground.Through the compatibility of deformation,the geogrid-reinforced and pile-supported foundation can fully utilize the bearing capacity of the pile,reduce settlement and differential settlement,and improve the bearing capacity and stability of the foundation.It is an effective soft soil foundation treatment technology.With a detailed assessment of scheme and calculation analysis,the PHC-AB500 with the space of 3 m and cap size of 1.8 m×1.8 m was selected as pile supported foundation with two-layer geogrid.The performance of the pile supported composite foundation was continuously monitored during the operation stage.The test results show that the measured load share ratio and foundation settlement are close to the calculated values,the load share ratio is gradually stabilized in the range of 70%-80%;and most of the settlement occurs during the filling construction stage with small post construction settlement.The static load test shows that the bearing capacity of pile network composite foundation meets the requirement.With the settlement of soil between the piles,the grid gradually takes effect,and the deformation and stress of the second layer of grid are larger than those of the first layer.
作者
田效军
黄达余
梅狄克
安春秀
TIAN Xiao-jun;HUANG Da-yu;MEI Di-ke;An Chun-xiu(Zhejiang Electric Power Design Institute of China Energy Engineering Group,Hangzhou 310012,Zhejiang,China)
出处
《地基处理》
2022年第5期423-429,共7页
Journal of Ground Improvement
关键词
变电站
桩网复合地基
土工格栅
差异沉降
托板
荷载分担比
substation
pile supported foundation
geogrid
differential settlement
pile cap
load share ratio
