基于MATLAB的CFG桩复合地基优化设计研究
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摘要
CFG桩复合地基是竖向增强体复合地基的一种,由于该方法可以掺入工业废料粉煤灰、不配筋以及充分发挥桩间土的承载能力,工程造价一般为桩基的1/3—1/2,经济效益和社会效益非常显著,因此得到越来越广泛的应用。目前比较常用的设计方法主要是先根据复合地基承载力来初选各项参数,再依据变形要求来调整参数,该方法需多次试算,且计算结果不一定经济。因此寻求更合理的设计计算方法变得非常迫切。
本文首先详细介绍了复合地基的基本理论,包括复合地基承载力和复合地基变形的计算方法,进而单独介绍了规范对CFG桩复合地基设计计算的要求。在CFG桩复合地基设计计算理论准备充分的情况下,引入了最优化设计理论。着重介绍了最优化问题模型的三要素包括:设计变量、目标函数和约束条件。并对最优化设计流程图做了介绍。然后简要介绍了MATLAB软件的基础知识,对MATLAB软件的流程控制语句做了具体介绍。
在此基础上,分析了CFG桩设计参数桩径d、桩长l、置换率m和桩体强度对复合地基加固效果的影响。通过建立60m厚的均质土体模型,运用MATLAB绘图演示了该关系。为CFG桩复合地基优化设计的设计参数选取提供了依据。
通过以上理论准备,本文选取了CFG桩复合地基的桩径d、桩长l、置换率m作为设计参数,并对桩体强度做了要求;以满足复合地基的承载力f_(spk)、控制总变形量s为约束条件;将CFG桩混合料的总用量定为目标函数;以能够实现CFG桩混合料用量最少的设计作为最优化设计。以MATLAB软件为优化计算平台,根据MATLAB流程控制语句的特点,建立了CFG桩复合地基优化设计的流程图。
本文选取了具体的工程实例,对其进行优化设计。以与原设计相同的沉降值作为变形控制条件,优化设计后CFG桩混合料的用量可以节约10%,取得了较显著的经济效益。
Cement Fly-ash Gravel (CFG) pile composite foundation is a kind of vertical reinforcement composite foundations. As industrial waste fly-ash can be added and no steel is needed in this method, as well as the bearing capacity of soil can be fully used, engineering cost of the CFG piles normally is only 1/3 to 1/2 of that for pile foundations. Due to remarkable economic and social benefits, CFG pile composite foundations are applied into engineering practice more and more widely. In general design each parameter is primarily assumed a value according to the required bearing capacity, and then it is adjusted to satisfy the settlement limitation of subsoils. It may take many trials in the calculation, while the result still may not be economical. Thus it becomes very urgent to look for a more reasonable design method.
Firstly, the basic theory of composite foundation is introduced, including the calculation methods about the bearing capacity and settlement of the composite foundation, then the requirements of the design calculation by standardization about CFG piles composite foundation are introduced. Secondly, following the theoretical preparation of CFG piles composite foundation is the optimization design theory. Emphasis is paid on three key elements of the optimization problem model, including design parameters, objective function and constraint conditions, and then is the flow chart of the optimization design. Thirdly, this paper briefly covers the basic knowledge of MATLAB software, and a specific introduction to the flow control statements of MATLAB software is shown.
The influence of design parameters which include pile diameter, pile length, area replacement rate and strength of the CFG piles on stabilization effect is analyzed. Through an established homogeneous soil mass model of 60m thick, the relationships between design parameters and bearing capacity and settlement of CFG pile composite foundation are shown by using the graphics of MATLAB. This work provides basis to select the design parameters for the optimization design of CFG piles composite foundation.
According to above-mentioned theoretical preparation, the author adopts the pile diameter, pile length, and area replacement rate as the main design parameters, while considering the strength of the piles. The permitted bearing capacity of composite foundation and total controlling settlement are taken as the constraint conditions, and the total volume of the CFG piles mixture is selected as the objective function. The design achieving the least amount of the CFG piles mixture is the optimum one. Using MATLAB as a computing platform, the author sets up a flow chart of the optimization design according to the features of MATLAB's flow control statements.
In the paper, a practical engineering project is taken as an example to carry out optimization analysis. With the same settlement value in original design, it shows the volume of CFG piles mixture in the case can be saved up to 10%.
本文首先详细介绍了复合地基的基本理论,包括复合地基承载力和复合地基变形的计算方法,进而单独介绍了规范对CFG桩复合地基设计计算的要求。在CFG桩复合地基设计计算理论准备充分的情况下,引入了最优化设计理论。着重介绍了最优化问题模型的三要素包括:设计变量、目标函数和约束条件。并对最优化设计流程图做了介绍。然后简要介绍了MATLAB软件的基础知识,对MATLAB软件的流程控制语句做了具体介绍。
在此基础上,分析了CFG桩设计参数桩径d、桩长l、置换率m和桩体强度对复合地基加固效果的影响。通过建立60m厚的均质土体模型,运用MATLAB绘图演示了该关系。为CFG桩复合地基优化设计的设计参数选取提供了依据。
通过以上理论准备,本文选取了CFG桩复合地基的桩径d、桩长l、置换率m作为设计参数,并对桩体强度做了要求;以满足复合地基的承载力f_(spk)、控制总变形量s为约束条件;将CFG桩混合料的总用量定为目标函数;以能够实现CFG桩混合料用量最少的设计作为最优化设计。以MATLAB软件为优化计算平台,根据MATLAB流程控制语句的特点,建立了CFG桩复合地基优化设计的流程图。
本文选取了具体的工程实例,对其进行优化设计。以与原设计相同的沉降值作为变形控制条件,优化设计后CFG桩混合料的用量可以节约10%,取得了较显著的经济效益。
Cement Fly-ash Gravel (CFG) pile composite foundation is a kind of vertical reinforcement composite foundations. As industrial waste fly-ash can be added and no steel is needed in this method, as well as the bearing capacity of soil can be fully used, engineering cost of the CFG piles normally is only 1/3 to 1/2 of that for pile foundations. Due to remarkable economic and social benefits, CFG pile composite foundations are applied into engineering practice more and more widely. In general design each parameter is primarily assumed a value according to the required bearing capacity, and then it is adjusted to satisfy the settlement limitation of subsoils. It may take many trials in the calculation, while the result still may not be economical. Thus it becomes very urgent to look for a more reasonable design method.
Firstly, the basic theory of composite foundation is introduced, including the calculation methods about the bearing capacity and settlement of the composite foundation, then the requirements of the design calculation by standardization about CFG piles composite foundation are introduced. Secondly, following the theoretical preparation of CFG piles composite foundation is the optimization design theory. Emphasis is paid on three key elements of the optimization problem model, including design parameters, objective function and constraint conditions, and then is the flow chart of the optimization design. Thirdly, this paper briefly covers the basic knowledge of MATLAB software, and a specific introduction to the flow control statements of MATLAB software is shown.
The influence of design parameters which include pile diameter, pile length, area replacement rate and strength of the CFG piles on stabilization effect is analyzed. Through an established homogeneous soil mass model of 60m thick, the relationships between design parameters and bearing capacity and settlement of CFG pile composite foundation are shown by using the graphics of MATLAB. This work provides basis to select the design parameters for the optimization design of CFG piles composite foundation.
According to above-mentioned theoretical preparation, the author adopts the pile diameter, pile length, and area replacement rate as the main design parameters, while considering the strength of the piles. The permitted bearing capacity of composite foundation and total controlling settlement are taken as the constraint conditions, and the total volume of the CFG piles mixture is selected as the objective function. The design achieving the least amount of the CFG piles mixture is the optimum one. Using MATLAB as a computing platform, the author sets up a flow chart of the optimization design according to the features of MATLAB's flow control statements.
In the paper, a practical engineering project is taken as an example to carry out optimization analysis. With the same settlement value in original design, it shows the volume of CFG piles mixture in the case can be saved up to 10%.
引文
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[7]张世尧,陈涛,顾祥林.以沉降控制的掺粉煤灰水泥粉喷桩优化设计方法[J].地基基础.2003,1:29-34
[8]许明军.高速公路碎石桩处理液化地基的优化设计研究[D].南京:东南大学,2004
[9]芮瑞.刚性桩加固软土地基的路堤荷载传递机理与优化研究[D].武汉:武汉理工大学,2007
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[15]尚新生.多元复合地基工作机理及优化设计研究[D].西安:西安理工大学,2004
[16]蒋金锋,陈银深.水泥土桩复合地基的优化设计方法研究[J].西部探矿工程.2006,2:40-41
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[18]孙琳娜.复合地基的沉降及按沉降控制的优化设计研究:[D].杭州.浙江大学建筑工程学院岩土工程专业.2006
[19]朱筱嘉.带帽刚性疏桩复合地基数值分析和优化设计研究[D].南京:河海大学,2007
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[22]牛顺生.长短桩组合型复合地基智能优化设计方法研究[D].长沙:湖南大学,2006
[23]李茂英,曾庆军,莫海鸿,等.高速公路拓宽工程沉降控制复合地基优化设计[J].岩土力学.2008,29(2):535-540
[24]徐玉芬.刚性长桩与柔性短桩复合地基优化设计[D].南京:东南大学,2005
[25]甘先永.基于ANSYS的粉喷桩复合地基设计方案优化[J].铁道科学与工程学报.2006.3(2):58-61
[26]李永刚,李宁.中心布桩复合地基优化设计的数值分析[A].中国土木工程学会第九届土力学及岩土工程学术会议论文集[C].北京.2003,10:854-859
[27]M.Enoki,N.Yagi,R.Yatabe,etal.Shearing Characteristic of Composite Ground and It's Application to Stability Analysis[J].Deep Foundation Improvement:Design Construction and Testing,ASTM,1991
[28]Bransby M F.Springman S M.3-D finite element modeling of pile groups adjacent to surcharge loads[J].Computers and Geotechnics.1996,19(4).301-324.
[29]Mirza U A A.Pile skin friction in clays[J].International Journal of Offshore and Polar Engineering.1997,7(1):77-80
[30]Meyerhof G.G..Some recent foundation research and its application to design.The Structure Engineer.Vol.31,1953,No.6,151-167
[31]Meyerhof G.G.,Ranjan G..The bearing capacity of rigid piles under inclined loads in sand.Vertical piles.Canadian Geotechnical Journal.1972,9(4):440-446
[32]Meyerhof G.G.,Sastry.Bearing capacity of rigid piles under eccentric and inclined loads.Canadian Geotechnical Journal.1985,22(3):267-275
[33]Meyerhof G.G.Behavior of pile foundations under special loading conditions:1994 R.M hardy keynote address.Canadian Geoteehnical Journal,1995,32(2):204-219
[34]郑俊杰.地基处理技术[M].武汉:华中科技大学出版社,2004.88,197
[35]王吉望.复合地基的现状与发展[J].冶建总院院刊,1990.2
[36]盛崇文.振动水冲法[M].北京:水利电力出版社,1983
[37]Hughes J.M.O.,Withes N.J..Reinforcing Soft Cohesive Soils with Stone Columns.Ground Engineering,(7),3,1974
[38]Brauns J..Die Anfangstraglast von Schottersaulen in Bindingen Unterground.Die Bautechnik,8.1978
[39]Broms B.B.Soil Improvement Methods in Southeas Asia Regional Conf.on SMFE Vol.2,1987
[40]Geddes J.D.Stresses in Foundation Soils Due to Vertical Subsurface Load,Geotechnique,Vol.16,231,1966
[41]王恩远,吴迈.工程实用地基处理手册[M].北京:中国建材工业出版社,2005.125
[42]叶书麟,叶观宝.地基处理[M].第二版.上海:中国建筑工业出版社,2004.76.
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[44]中华人民共和国建设部.GB50007-2002.建筑地基基础设计规范.北京:中国建筑工业出版社出版,2002
[45]闫明礼,张东刚.CFG桩复合地基技术及工程实践[M].第二版.北京:中国水利水电出版社,2006.111
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[2]龚晓南.复合地基理论及工程应用[M].第二版.北京:中国建筑工业出版社,2007.1,68,87-89,122
[3]李作勤.复合地基中桩土应力比和优化设计[J].岩土力学.1995,16(4):30-37
[4]陈兵.复合地基中优化设计参数的方法[J].安徽建筑.2002,3:86-87
[5]鲁长亮,黄生文,朱树彬.桩承土工加筋地基桩土应力比计算及其优化设计[J].西部探矿工程.2005,5:43-45
[6]马洪友.同三高速(珠海段)软土地基处理方法及基层优化设计[D].长春:吉林大学,2006
[7]张世尧,陈涛,顾祥林.以沉降控制的掺粉煤灰水泥粉喷桩优化设计方法[J].地基基础.2003,1:29-34
[8]许明军.高速公路碎石桩处理液化地基的优化设计研究[D].南京:东南大学,2004
[9]芮瑞.刚性桩加固软土地基的路堤荷载传递机理与优化研究[D].武汉:武汉理工大学,2007
[10]苏克俭,张季超,江毅,等.复合地基在南沙地基基础优化设计中的应用[A].第16届全国结构工程学术会议[C].2007
[11]李志远.粉喷桩软基处理的优化设计研究[J].广东土木与建筑.2007,6:28-30
[12]刘涛.CFG桩复合地基三维有限元分析及优化设计[D].南京:南京理工大学,2006
[13]李建光.组合桩复合地基沉降变形研究及优化设计探讨[D].成都:成都理工大学,2002
[14]陈丽萍.长短桩复合地基设计理论研究[D].武汉:武汉理工大学,2007
[15]尚新生.多元复合地基工作机理及优化设计研究[D].西安:西安理工大学,2004
[16]蒋金锋,陈银深.水泥土桩复合地基的优化设计方法研究[J].西部探矿工程.2006,2:40-41
[17]王金山,唐小兵,杨永谦.复合地基的优化设计[J].2001年船舶与海洋工程研究专集,2001,143:120-121,126
[18]孙琳娜.复合地基的沉降及按沉降控制的优化设计研究:[D].杭州.浙江大学建筑工程学院岩土工程专业.2006
[19]朱筱嘉.带帽刚性疏桩复合地基数值分析和优化设计研究[D].南京:河海大学,2007
[20]Mindlin,R.D..Force at a point in the interior of a semi-infinite solid[J].Physics,1936,7(2):195-202.
[21]王松江.CFG桩联合碎石桩长短桩结合的复合地基优化设计研究[D].南京:河海大学,2005
[22]牛顺生.长短桩组合型复合地基智能优化设计方法研究[D].长沙:湖南大学,2006
[23]李茂英,曾庆军,莫海鸿,等.高速公路拓宽工程沉降控制复合地基优化设计[J].岩土力学.2008,29(2):535-540
[24]徐玉芬.刚性长桩与柔性短桩复合地基优化设计[D].南京:东南大学,2005
[25]甘先永.基于ANSYS的粉喷桩复合地基设计方案优化[J].铁道科学与工程学报.2006.3(2):58-61
[26]李永刚,李宁.中心布桩复合地基优化设计的数值分析[A].中国土木工程学会第九届土力学及岩土工程学术会议论文集[C].北京.2003,10:854-859
[27]M.Enoki,N.Yagi,R.Yatabe,etal.Shearing Characteristic of Composite Ground and It's Application to Stability Analysis[J].Deep Foundation Improvement:Design Construction and Testing,ASTM,1991
[28]Bransby M F.Springman S M.3-D finite element modeling of pile groups adjacent to surcharge loads[J].Computers and Geotechnics.1996,19(4).301-324.
[29]Mirza U A A.Pile skin friction in clays[J].International Journal of Offshore and Polar Engineering.1997,7(1):77-80
[30]Meyerhof G.G..Some recent foundation research and its application to design.The Structure Engineer.Vol.31,1953,No.6,151-167
[31]Meyerhof G.G.,Ranjan G..The bearing capacity of rigid piles under inclined loads in sand.Vertical piles.Canadian Geotechnical Journal.1972,9(4):440-446
[32]Meyerhof G.G.,Sastry.Bearing capacity of rigid piles under eccentric and inclined loads.Canadian Geotechnical Journal.1985,22(3):267-275
[33]Meyerhof G.G.Behavior of pile foundations under special loading conditions:1994 R.M hardy keynote address.Canadian Geoteehnical Journal,1995,32(2):204-219
[34]郑俊杰.地基处理技术[M].武汉:华中科技大学出版社,2004.88,197
[35]王吉望.复合地基的现状与发展[J].冶建总院院刊,1990.2
[36]盛崇文.振动水冲法[M].北京:水利电力出版社,1983
[37]Hughes J.M.O.,Withes N.J..Reinforcing Soft Cohesive Soils with Stone Columns.Ground Engineering,(7),3,1974
[38]Brauns J..Die Anfangstraglast von Schottersaulen in Bindingen Unterground.Die Bautechnik,8.1978
[39]Broms B.B.Soil Improvement Methods in Southeas Asia Regional Conf.on SMFE Vol.2,1987
[40]Geddes J.D.Stresses in Foundation Soils Due to Vertical Subsurface Load,Geotechnique,Vol.16,231,1966
[41]王恩远,吴迈.工程实用地基处理手册[M].北京:中国建材工业出版社,2005.125
[42]叶书麟,叶观宝.地基处理[M].第二版.上海:中国建筑工业出版社,2004.76.
[43]中华人民共和国建设部.JGJ79-2002.建筑地基处理技术规范.北京:筑龙网,2002
[44]中华人民共和国建设部.GB50007-2002.建筑地基基础设计规范.北京:中国建筑工业出版社出版,2002
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