高速铁路采空区桥基变形数值模拟分析
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摘要
目前国内高速铁路设计对于大型采空区都进行了绕避,针对无法绕避的小采空区和采空巷道都采取了相应的工程措施,高速铁路采空区桥基桩台基础的应用在国内研究的较少,本文基于合福铁路上饶官山底特大桥59号墩台(DK499+584.180)和62号墩台(DK499+682.28),通过有限差分软件FLAC3D进行数值建模,研究分析了两个墩台在上部荷载作用下的沉降变形规律,荷载传递规律等。主要研究内容和成果如下：
(1)对采空区桥基变形、稳定性、治理技术以及数值模拟方法的国内外研究现状进行了比较详细的叙述。
(2)对两个墩台进行数值模拟分析后表明,在穿过采空区的桥墩下方应用桩基础加固可以减小桩间土承担的荷载,并显著减小地层和基础的沉降量,同时对采空区的沉降起到了抑制作用,证明这样的处理方法对采空区桥基有很好的加固效果。
(3)对两个墩台的沉降变形进行研究分析,沉降随着荷载的增大而增大,不同深度的地层中,越是浅层土,沉降量越大；桩间土和桩顶的沉降量有细微差别,但可以忽略不计,桩土相对位移随着荷载增大而增大,但趋势也渐渐平缓。
(4)对两个墩台的荷载传递机理进行研究分析,随着上部荷载的不断增大,桩身轴力从桩顶到桩底呈减小趋势,桩顶轴力最大,它的变化趋势随荷载的增大而增大；穿过采空区的桩,在该段由于没有与地层接触,轴力保持不变；桩身侧摩阻力随上部荷载的增大,先增大,然后再减小,穿过采空区的桩,在该段数值为零；桩土应力比以及桩荷载分担比随荷载增大而增大,桩开始承担更多的荷载。
Mineral resources are rich and are widely distributed in China. Because of the historical reasons, most of the gobs for mining are abandoned without effective governance. There is a large area of ground subsidence and fissures in the stage of development of the mined-out area, although some mined-out areas have not been clearly changed, they still have a serious threat to the construction and the people's lives and property. And the mined-out area is one of the potential geological disasters by human activities.
In this dissertation, based on the number59pier section of DK499+584.180and the number62pier section of DK499+682.28in GuanShanDi bridge of HeFu railway, the numerical modeling is built by finite difference software FLAC3D, this dissertation studies the regularity of the settlement deformation and the load transfer of the two piers under the influence of the upper load. The main contents and results are as follows:
(1) The research status of the numerical simulation method at home and abroad about the deformation of the bridge foundation, the stability and the governance of technology of the goaf is summarized systematically.
(2) Analyze the numerical simulation, which shows that the pile foundation under the pier which is through the mined-out area is reinforced to reduce the sharing load in the soil among piles and reduce dramatically the settlement between the stratum and the foundation. Meanwhile, it is inhibiting the settlement of the mined-out area. All above prove this handling method has good reinforcement effect on the bridge foundation in the mined-out area.
(3) A numerical simulation has been conducted to study the law of settlement, and the results suggested that sedimentation increases as the load increases. The more shallow location, the greater amount of settlement for soil layers at different depth. There are some differences in the soil among piles and the top of the pile for the pile settlement however it is negligible. The relative displacement of the pile-soil increases as the load increases and the trend has gradually getting gentle.
(4) Analyze the load transfer mechanism of two piers, which suggests that the pile axial force reduces from the top of the pile to the bottom of the pile as the load increases, the axial force which is at the top of the pile is maximum and increases with the increment of the load: The axial force remains unchangeable while the pile passes through the gob, because there is no contact with the formation in this section; The pile skin friction increases first and then reduces as the load increases, the figure is zero in this section while the pile passes through the gob. The increase of the pile-soil stress ratio and the pile load sharing ratio shows that the piles begin to take on more loads.
(1)对采空区桥基变形、稳定性、治理技术以及数值模拟方法的国内外研究现状进行了比较详细的叙述。
(2)对两个墩台进行数值模拟分析后表明,在穿过采空区的桥墩下方应用桩基础加固可以减小桩间土承担的荷载,并显著减小地层和基础的沉降量,同时对采空区的沉降起到了抑制作用,证明这样的处理方法对采空区桥基有很好的加固效果。
(3)对两个墩台的沉降变形进行研究分析,沉降随着荷载的增大而增大,不同深度的地层中,越是浅层土,沉降量越大；桩间土和桩顶的沉降量有细微差别,但可以忽略不计,桩土相对位移随着荷载增大而增大,但趋势也渐渐平缓。
(4)对两个墩台的荷载传递机理进行研究分析,随着上部荷载的不断增大,桩身轴力从桩顶到桩底呈减小趋势,桩顶轴力最大,它的变化趋势随荷载的增大而增大；穿过采空区的桩,在该段由于没有与地层接触,轴力保持不变；桩身侧摩阻力随上部荷载的增大,先增大,然后再减小,穿过采空区的桩,在该段数值为零；桩土应力比以及桩荷载分担比随荷载增大而增大,桩开始承担更多的荷载。
Mineral resources are rich and are widely distributed in China. Because of the historical reasons, most of the gobs for mining are abandoned without effective governance. There is a large area of ground subsidence and fissures in the stage of development of the mined-out area, although some mined-out areas have not been clearly changed, they still have a serious threat to the construction and the people's lives and property. And the mined-out area is one of the potential geological disasters by human activities.
In this dissertation, based on the number59pier section of DK499+584.180and the number62pier section of DK499+682.28in GuanShanDi bridge of HeFu railway, the numerical modeling is built by finite difference software FLAC3D, this dissertation studies the regularity of the settlement deformation and the load transfer of the two piers under the influence of the upper load. The main contents and results are as follows:
(1) The research status of the numerical simulation method at home and abroad about the deformation of the bridge foundation, the stability and the governance of technology of the goaf is summarized systematically.
(2) Analyze the numerical simulation, which shows that the pile foundation under the pier which is through the mined-out area is reinforced to reduce the sharing load in the soil among piles and reduce dramatically the settlement between the stratum and the foundation. Meanwhile, it is inhibiting the settlement of the mined-out area. All above prove this handling method has good reinforcement effect on the bridge foundation in the mined-out area.
(3) A numerical simulation has been conducted to study the law of settlement, and the results suggested that sedimentation increases as the load increases. The more shallow location, the greater amount of settlement for soil layers at different depth. There are some differences in the soil among piles and the top of the pile for the pile settlement however it is negligible. The relative displacement of the pile-soil increases as the load increases and the trend has gradually getting gentle.
(4) Analyze the load transfer mechanism of two piers, which suggests that the pile axial force reduces from the top of the pile to the bottom of the pile as the load increases, the axial force which is at the top of the pile is maximum and increases with the increment of the load: The axial force remains unchangeable while the pile passes through the gob, because there is no contact with the formation in this section; The pile skin friction increases first and then reduces as the load increases, the figure is zero in this section while the pile passes through the gob. The increase of the pile-soil stress ratio and the pile load sharing ratio shows that the piles begin to take on more loads.
引文
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[2]C.J.F.P.Jones and T.D.Rourke.Mining Subsidence Effects on Transportation Facilities, MIS.,1988(7): 107-126
[3]Eric.C.Drum.Mechanism of Subsidence Induced Damage and Technique for Analysis, MIS.,1985(10): 168-190
[4]M.C.Wang.Settlement Behavior of Footing Above a Void, PCGGE, New orleans,1982:168-183
[5]孙超,薄景山,孙有为等.采空区沉陷研究历史及现状.防灾科技学院学报,2008,10(4)
[6]孙宗第.高等级公路下伏空洞勘探、危害程度评价及处治研究报告集[R].北京：科学出版社,2000
[7]郭广礼.老采空区上方建筑地基变形机理及其控制[M].徐州：中国矿业大学出版社,2001
[8]隋旺华,沈文.浅部采空区岩层移动的工程地质分析及有限元模拟[J].煤炭学报,1991,15(3)：72-82
[9]邓喀中,马伟民.开采沉陷中的岩体节理效应[J].岩石力学与工程学报,1996,15(4)：345-352
[10]Cui Ximin. Improved prediction of differential subsidence caused by underground mining[J]. Rock Mechanics and Mining Sciences,2000,37(4):615-627
[11]Donnelly L J. The monitoring and prediction of mining subsidence in the Amaga, Angelopolis, Venecia and BolomboloRegions, Antioquia, Colombia[J]. Engineering Geology,2001,59(1/2): 103-114
[12]成枢.岩层与地表移动数值分析新方法[M].北京：中国矿业大学出版社,1998
[13]谢和平,周宏伟,王金安等.FLAC在煤矿开采沉陷预测中的应用及对比分析[J].岩石力学与工程学报,1999,18(4)：397-401
[14]高谦,乔兰等.地下工程系统分析与设计[M].北京：中国建材工业出版社,2005
[15]赵静波,高谦,李莉.地下采动岩层移动预测理论分析与研究[J].矿冶工程,2004(3)：1-4
[16]尹士献.厚黄土覆盖层村镇下条带开采研究[D].西安科技大学.2004
[17]徐永圻.煤矿开采学[M].徐州：中国矿业大学出版社1999
[18]于广明.矿山开采沉陷非线性理论与实践导引[M].北京：煤炭工业出版社,1998
[19]何国清、杨伦编.矿山开采沉陷学.北京：中国矿业大学出版社,1991
[20]蒋金平.老采空区上建高速公路的工程地质适应性及治理研究.矿山压力与顶板管理,2003
[21]吴兆营,薄景山,杜国林等.采空区对地表稳定性的影响.自然灾害学报,2004,13(2),114
[22]孙雅洁,孙占法等.荷载作用下老采空区上方地表移动变形规律的数值模拟研究.华北科技学院学报,2006,3(2),9
[23]伍永田,张旭生.采空区塌陷的离散元模拟.采矿技术,2008：8(1),73-74
[24]金爱兵,明世祥等.采空区地表沉陷及移动规律的数值模拟.采矿技术,2008,8(4),70。
[25]王玉标,李永斌.断层地质构造对采空区路基路堑稳定性的影响.山西建筑,2008,34(32)： 267～268
[26]孙超,薄景山等.采空区地表沉降影响因素研究.吉林大学学报(地球科学版),2009,39(3)：498～501
[27]白志辉,李亮等.老采空区上方地基稳定性及残余变形规律研究.煤矿开采,2009
[28]李森林,马博恒等.基建场地下伏采空区剩余沉降量的数值模拟.勘查科学技术,2009,33～35
[29]齐辉,商庆森,朱海波等.采空区公路沥青路面结构层应力关键影响因素分析,2009
[30]朱友群,施斌,王宝军.边坡高填方路基下伏多层采空区稳定性数值模拟评价,2008,17(3)：394-395
[31]向龙,肖均,陈寿根.采空区上覆岩体离层发展规律研究,公路隧道,2009,(3)：13
[32]王树仁,张海清,慎乃齐.穿越采空区桥隧工程危害效应分析及对策.解放军理工大学学报(自然科学版),2009,10(5)：492
[33]张建文,王树仁,贾会会.地面施工载荷对采空区顶板变形破坏效应分析.煤炭科学技术,2010,38(9)：19
[34]杨令强,武甲庆,秦冰.地下采空区堤防工程的变形与稳定分析.水利水电技术,2007,11(38)：37
[35]饶为国,刘文娟,许玉德.地下采空区对高填路堤边坡稳定的影响.岩土工程界,2005,9(4)：37
[36]刁心宏,刘峰,习小华.采空区对公路路基稳定性影响的离散元法分析[J],路基工程,2006,(6)：91-93
[37]张志沛,王芝银,刘旭.高速公路与下伏煤矿采空区的长期稳定性分析[J],西安科技大学学报,2005,25(4)：415-419
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