城市下穿隧道明挖段抗浮桩设计的关键问题探讨
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摘要
为了得到明挖隧道敞开段抗浮桩受力性能,基于截条法理论,建立考虑岩土-桩基相互作用计算模型,对抗浮桩受力性能进行研究。结果表明:常规的布置方法抗浮桩边桩布置于侧墙底,中桩根据底板的跨度与边桩接近等距离布置,压力水头确定后,由桩基平均分担底板水浮力与结构自重的差值,计算出桩基受力性能与工程实际差异较大。在水平土压力作用下,中桩约为边桩抗力的2倍,因此按平均分配抗拔力的方法计算出的桩长及配筋易引起结构耐久性及安全性问题。工程设计时可采用整体抗浮法验算结构抗浮稳定性,确定抗拔基桩根数,采用截条法计算结构受力,经过计算确定基桩布置,使每根桩受力均匀合理。
In order to reasonably obtain the mechanical properties of anti-floating piles in open-cut tunnels,a calculation model considering rock-soil-pile interaction is established to study the mechanical properties of anti-floating piles. The results show that:in the conventional layout method,the side piles of anti-floating piles are arranged under the side wall and the middle piles are arranged according to the span of the bottom plate and equidistantly from the side piles. In design calculation the pressure head is determined and the influence of lateral wall horizontal pressure on uplift piles is neglected,which leads to a great difference between the calculation of pile foundation stress and the actual engineering. When the side piles are arranged under the side wall,the force of the middle piles is about twice that of the side piles,which leads to the large pull-out force of the middle piles. The calculation of the length of the piles and the reinforcement distribution according to the average pull-out force can easily lead to the durability and safety problems of the structure. The integral anti-floating method is used to check the anti-floating stability of the structure. The integral anti-floating method is used to check the anti-floating stability of the structure. The number of uplift piles is determined,the force of structure is calculated by section method,and the arrangement of foundation piles is determined by calculation,so that the force of each pile can be uniform and reasonable.
In order to reasonably obtain the mechanical properties of anti-floating piles in open-cut tunnels,a calculation model considering rock-soil-pile interaction is established to study the mechanical properties of anti-floating piles. The results show that:in the conventional layout method,the side piles of anti-floating piles are arranged under the side wall and the middle piles are arranged according to the span of the bottom plate and equidistantly from the side piles. In design calculation the pressure head is determined and the influence of lateral wall horizontal pressure on uplift piles is neglected,which leads to a great difference between the calculation of pile foundation stress and the actual engineering. When the side piles are arranged under the side wall,the force of the middle piles is about twice that of the side piles,which leads to the large pull-out force of the middle piles. The calculation of the length of the piles and the reinforcement distribution according to the average pull-out force can easily lead to the durability and safety problems of the structure. The integral anti-floating method is used to check the anti-floating stability of the structure. The integral anti-floating method is used to check the anti-floating stability of the structure. The number of uplift piles is determined,the force of structure is calculated by section method,and the arrangement of foundation piles is determined by calculation,so that the force of each pile can be uniform and reasonable.
引文
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[2]黄琪祺,周健.抗浮锚杆在工程设计中的应用[J].土工基础,2008,22(3):1-3.
[3]刘发前.地下结构抗浮设计讨论[J].城市道桥与防洪,2010(6):211-213+243.
[4]王立波.浅析明挖隧道抗拔桩设计[J].江苏建筑,2012(1):93-95.
[5]张跃明.抗拔桩变形及对地铁车站结构计算影响分析[J].隧道建设,2014,34(6):519-524.
[6]朱斌.地铁车站抗拔桩设计计算分析方法[J].工程与建设,2014,28(2):239-241.
[7]何日雄.基于桩顶位移协调的地下室底板抗浮设计[J].建筑结构,2014,44(8):40-43.
[8]建筑地基基础设计规范:GB 5007-2011[S].北京:中国建筑工业出版社,2011.
[9]陈锦剑,王建华,范巍,等.抗拔桩在大面积深开挖过程中的受力特性分析[J].岩土工程学报,2009,31(3):402-407.
[10]陈希哲,叶菁.土力学地基基础(第5版)[M].北京:清华大学出版社,2013.