狭长深基坑支护结构设计的有限元分析
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摘要
以南京某地铁车站深基坑工程为研究对象,介绍该工程场区的地质条件,支护形式及施工工序;分析该基坑在开挖过程中围护结构的位移、支撑轴力及基坑周围土体地表沉降的变化,通过有限元软件Plaxis对基坑开挖进行数值模拟,并将计算结果与实测结果进行比较分析,二者结果基本吻合,并且通过进一步研究得到了支护结构抗弯刚度EI、坑边超载及开挖对基坑变形规律的影响结果。增加支护结构的抗弯刚度能一定程度减小地连墙的水平位移,随着坑边超载P的不断增大墙顶水平位移不断加大,当P=50 k Pa时,围护结构墙顶范围内发生明显屈服。而随着开挖深度的不断增大,超载对地连墙水平位移的影响系数不断减小。基坑开挖时。地下连续墙最大侧移位置大致位于开挖面附近,且随着开挖深度的增大而逐渐下移。当土体开挖至坑底且未施工底板和垫层时,此时基坑处于最危险状态。
In deep foundation pit engineering of nanjing subway station as the research object, introduces the engi-neering geological conditions in jobsite, the support form and construction process; Analysis of the foundation pitdisplacement of retaining structure in the process of excavation and supporting axial force and the change of thesurface settlement of soil around the foundation pit, the pit excavation are numerically simulated by finite elementsoftware Plaxis, analysis and comparing the calculated results with measured results, the two results are basicallyconsistent, and the supporting structure is obtained by further research on bending stiffness EI, pit overload andthe result of the influence of excavation of foundation pit deformation law. Can increase the flexural stiffness of sup-porting structure to a certain extent reduce the horizontal displacement of wall, with the increase of test pit over-load P wall top horizontal displacement increasing, when P = 50 k Pa, retaining wall structure within the scope ofapparent yield. As the increasing of excavation depth, the overload of the wall and decreases the influence of thehorizontal displacement coefficient. In the excavation of foundation pit. Underground continuous wall maximum lat-eral position near the excavation surface, and down gradually along with the increase of excavation depth. Whenthe soil excavation to the bottom slab and cushion layer, and construction at the moment of foundation pit in themost dangerous state.
In deep foundation pit engineering of nanjing subway station as the research object, introduces the engi-neering geological conditions in jobsite, the support form and construction process; Analysis of the foundation pitdisplacement of retaining structure in the process of excavation and supporting axial force and the change of thesurface settlement of soil around the foundation pit, the pit excavation are numerically simulated by finite elementsoftware Plaxis, analysis and comparing the calculated results with measured results, the two results are basicallyconsistent, and the supporting structure is obtained by further research on bending stiffness EI, pit overload andthe result of the influence of excavation of foundation pit deformation law. Can increase the flexural stiffness of sup-porting structure to a certain extent reduce the horizontal displacement of wall, with the increase of test pit over-load P wall top horizontal displacement increasing, when P = 50 k Pa, retaining wall structure within the scope ofapparent yield. As the increasing of excavation depth, the overload of the wall and decreases the influence of thehorizontal displacement coefficient. In the excavation of foundation pit. Underground continuous wall maximum lat-eral position near the excavation surface, and down gradually along with the increase of excavation depth. Whenthe soil excavation to the bottom slab and cushion layer, and construction at the moment of foundation pit in themost dangerous state.
引文
[1]台运好,吕凤梧,贾福源.基坑开挖渗流场与应力场耦合计算及其环境影响分析[J].结构工程师,2008,24(6):116-119.
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[5]乔亚飞,丁文其,王军,王春波.无锡地区地铁车站深基坑变形特性[J].岩土工程学报,2012,(S1):761-766.
[6]李淑,张顶立,房倩.北京地区深基坑墙体变形特性研究[J].岩石力学与工程学报,2012,31(11):2344-2353.
[7]吕爱钟,蒋斌松.岩石力学反问题[M].北京:煤炭工业出版社,1998.
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[9]姜忻良,徐炳伟.狭长基坑中地下连续墙的简化计算模型[J].工程力学,2009,26(6):33-36.
[10]高俊合,赵维炳.土体非线性影响的深基坑支护研究综述[J].水利水电科技进展,1997,17(4):14-17.
[11]JARDINE R J,FOURIE A B,BURLAND J B.Studies of the influence of non-linear stress-strain characteristics in soil-structureinteraction[J].Geotechnique,1986,36(3):377-396.
[2]刘建航,侯学渊.基坑工程手册[M].北京:中国建筑工业出版社,1997.
[3]武文永,曹雪山.南京地铁鸡鸣寺站地下连续墙深层水平位移特性研究[J].华东交通大学学报,2014(3),115-119
[4]徐中华,王建华,王卫东.上海地区深基坑工程中地下连续墙的变形性状[J].土木工程学报,2008,41(8):81-86.
[5]乔亚飞,丁文其,王军,王春波.无锡地区地铁车站深基坑变形特性[J].岩土工程学报,2012,(S1):761-766.
[6]李淑,张顶立,房倩.北京地区深基坑墙体变形特性研究[J].岩石力学与工程学报,2012,31(11):2344-2353.
[7]吕爱钟,蒋斌松.岩石力学反问题[M].北京:煤炭工业出版社,1998.
[8]JANBU J.Soil compressibility as determined by oedometer and triaxial tests[J].ECSMFE Wiesbaden,1963(1):19-25.
[9]姜忻良,徐炳伟.狭长基坑中地下连续墙的简化计算模型[J].工程力学,2009,26(6):33-36.
[10]高俊合,赵维炳.土体非线性影响的深基坑支护研究综述[J].水利水电科技进展,1997,17(4):14-17.
[11]JARDINE R J,FOURIE A B,BURLAND J B.Studies of the influence of non-linear stress-strain characteristics in soil-structureinteraction[J].Geotechnique,1986,36(3):377-396.