滨海上覆吹填砂软土地基沉降预测及加固效果分析
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摘要
软土广泛分布在珠江三角洲地区,其工程性质差,孔隙比大、含水量高、强度低。软土地基承载力低,易于变形,在工程建设中难以满足工程需求,必须进行加固处理。实践证明,利用沿海地区丰富的泥沙资源用进行工程建设和软基处理是一种经济有效、方便快捷的方式。本文基于东莞市虎门港沙田港区(7、8#码头)二期工程堆载预压软基处理工程,运用FLAC~(3D)软件进行软基的固结沉降模拟,在前人工作的基础上,通过现场监测、理论研究、数值模拟等手段主要进行了以下几方面的工作:
1、首先介绍了几类常用的软基沉降预测方法和数值计算方法,并研究了袋装砂井的固结机理和特点;
2、对依托工程试验段的工程概况、设计方案、监测方案进行说明,通过对各种监测数据和相关资料进行系统分析研究,揭示了上覆吹填砂软土地基在吹填砂作用下竖向沉降及土体水平位移的发展趋势、孔隙水压力的分布规律;并结合室内试验和现场十字板剪切试验评价试验区的加固效果,总结一些影响软土地基加固效果的因素;
3、根据实测沉降数据,分别采用双曲线拟合法、指数曲线拟合法、Asaoka法以及改进泊松曲线模型对试验区分级加载下沉降进行了预测计算,并将几种方法的计算结果进行对比分析,总结出本文改进的方法更适用于上覆吹填砂软土地基沉降预测的结论,为类似工程提供依据和可借鉴经验。
4、通过砂井的简化方法和建立砂井的三维实体单元两种建模方式,利用FLAC~(3D)软件对试验区进行固结沉降计算,并将数值模拟结果与沉降监测数据相比较,发现软件模拟计算的结果与现场实测值吻合较好,验证了模型计算的准确性和实用性。
The soft soil widely distributes in Pearl River Delta area,its engineering characteristic is bad with bigger void ratio,higher water content,lower intensity.In engineering constructing ,we have to reinforce the soft ground because of its lower carrying capacity and aptness to deform. In fact,it is cost-effective and convenient in the coastal areas to use the resource-rich sediment for engineering and reinforcing. This article is based on the preloading soft foundation treatment of the second phase project in ShaTian port under HuMen port in DongGuan. Using the FLAC~(3D) software to do the settlement estimated simulation of the softweak ground work, based on the previous work, through the local testing, theoretic study, numerical value simulation ect ways, to do the mainly following aspects of works:
1.Firstly, several commonly prediction models and the numerical calculation methods of soft foundation settlement were given out,and the consolidation mechanism and consolidation characteristics of preloading with sand wick were researched.
2.Furthermore, this paper narrates the general situation, design program, monitoring program of the experimental segment.Then the author reveals the current of vertical settlement and horizontal displacement and the distributing disciplinarian for the soft soil foundation under the filled sand.Then the paper analysis the reinforcement effect with the data measured from laboratory test and vane shear test,and summarizes some elements to effect the reinforcement effect of soft soil foundation.
3.Thirdly, based on the actual settlement,the paper forecasts and calculates the experimental area settlement with stage loading by hyperbola method,exponential curve method, Asaoka method and modified posson curve.The calculation results of different methods are compared and analyzed to conclude that the proposed method is a suitable method to forecasts the settlement of the soft soil foundation under the filled sand.These solution can provide the basis and reference experience on the similar projects.
4.Finally, through the simplified method of sand drains and the establishment of sand drains'three-dimensional solid element,this paper uses FLAC~(3D) software to calculate the three-dimensional consolidation of the experimental area. Found the better consistent situation between the software simulation calculation result and the local testing result,and validate the veracity and practicability of the model calculation.
1、首先介绍了几类常用的软基沉降预测方法和数值计算方法,并研究了袋装砂井的固结机理和特点;
2、对依托工程试验段的工程概况、设计方案、监测方案进行说明,通过对各种监测数据和相关资料进行系统分析研究,揭示了上覆吹填砂软土地基在吹填砂作用下竖向沉降及土体水平位移的发展趋势、孔隙水压力的分布规律;并结合室内试验和现场十字板剪切试验评价试验区的加固效果,总结一些影响软土地基加固效果的因素;
3、根据实测沉降数据,分别采用双曲线拟合法、指数曲线拟合法、Asaoka法以及改进泊松曲线模型对试验区分级加载下沉降进行了预测计算,并将几种方法的计算结果进行对比分析,总结出本文改进的方法更适用于上覆吹填砂软土地基沉降预测的结论,为类似工程提供依据和可借鉴经验。
4、通过砂井的简化方法和建立砂井的三维实体单元两种建模方式,利用FLAC~(3D)软件对试验区进行固结沉降计算,并将数值模拟结果与沉降监测数据相比较,发现软件模拟计算的结果与现场实测值吻合较好,验证了模型计算的准确性和实用性。
The soft soil widely distributes in Pearl River Delta area,its engineering characteristic is bad with bigger void ratio,higher water content,lower intensity.In engineering constructing ,we have to reinforce the soft ground because of its lower carrying capacity and aptness to deform. In fact,it is cost-effective and convenient in the coastal areas to use the resource-rich sediment for engineering and reinforcing. This article is based on the preloading soft foundation treatment of the second phase project in ShaTian port under HuMen port in DongGuan. Using the FLAC~(3D) software to do the settlement estimated simulation of the softweak ground work, based on the previous work, through the local testing, theoretic study, numerical value simulation ect ways, to do the mainly following aspects of works:
1.Firstly, several commonly prediction models and the numerical calculation methods of soft foundation settlement were given out,and the consolidation mechanism and consolidation characteristics of preloading with sand wick were researched.
2.Furthermore, this paper narrates the general situation, design program, monitoring program of the experimental segment.Then the author reveals the current of vertical settlement and horizontal displacement and the distributing disciplinarian for the soft soil foundation under the filled sand.Then the paper analysis the reinforcement effect with the data measured from laboratory test and vane shear test,and summarizes some elements to effect the reinforcement effect of soft soil foundation.
3.Thirdly, based on the actual settlement,the paper forecasts and calculates the experimental area settlement with stage loading by hyperbola method,exponential curve method, Asaoka method and modified posson curve.The calculation results of different methods are compared and analyzed to conclude that the proposed method is a suitable method to forecasts the settlement of the soft soil foundation under the filled sand.These solution can provide the basis and reference experience on the similar projects.
4.Finally, through the simplified method of sand drains and the establishment of sand drains'three-dimensional solid element,this paper uses FLAC~(3D) software to calculate the three-dimensional consolidation of the experimental area. Found the better consistent situation between the software simulation calculation result and the local testing result,and validate the veracity and practicability of the model calculation.
引文
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[2] Sridharan A, Murthy N S & Prskask. Rettangula hypetbola method of consolidation analysis[J]. Geotechnique,Vol.37,No.3,1987,PP:355-368.
[3] Tan,T.S.Inoue,T.and Lee, S. L. Hyperbolic method for consolidation analysis [J], ASCE,JGED, Vol.117, No.Ⅱ,1991,PP:1723-1737.
[4]周焕云,黄晓明.高速公路软土地基沉降预测方法综述[J],交通运输工程学报,2002(4):7-10.
[5]李国维,杨涛,宋江波.公路软基沉降双曲线预测法的进一步探讨[J].公路交通科技,2003,20(1).
[6]潘林有、谢新宇.用曲线拟合的方法预测软土地基沉降[J],岩土力学,2004,,25(7):1053-1058.
[7]余景超.软基最终沉降量推算方法的比较及优化[J].武汉理工大学学报,2010,32(27).42-45
[8]李磊.地基沉降预测方法分析[D].浙江大学.2004
[9] Asaoka Akira. Observational procedure of settlement prediction [J].Soils and foundations, 1978,18(4):872101.
[10]刘松玉,经绯.软土地基上分期施工的路堤沉降预测方法[J].岩土工程学报,2003,25(2).228-232
[11]宰金珉,梅国雄.全过程的沉降量预测方法研究[J].岩土力学,2000,20(4):322-325.
[12]梅国雄,宰金珉殷宗泽等.沉降-时间曲线呈“S”型的证明——从一维固结理论角度[J].岩土力学,2004,25(1):20-22.
[13]梅国雄,宰金珉,殷宗泽等.沉降-时间曲线呈“S”型的证明及其应用——从土体本构关系[J].岩土力学,2005,26:21-24.
[14]王立忠编著.岩土工程现场监测技术及应用[M].杭州:浙江大学出版社,2000.
[15]石世云.多变量灰色模型MGM(1,n)在变形预测中的应用[J].测绘通报,1998,10.
[16]张仪萍,张土乔,龚晓南.沉降的灰色预测[J].工业建筑,1999,29(3):45-48,57.
[17]张仪萍,俞亚南等.沉降预测中的灰色模型理论与Asaoka法[J].系统工程理论与实践,2002,9:141-144
[18]曾超,肖锋等.应用灰色模型(G,M)预测软土路基沉降量[J].安全与环境工程,2002,1(9):17-19
[19]刘勇键.用人工神经网络预测高速公路软土地基的最终沉降[J].公路交通科技,2000,17(6):15-18.
[20]米鸿燕,蒋兴华.基于灰色BP神经网络的沉降预测模型应用研究[J].昆明理工大学学报,2007,32(2):65-68
[21]胡伍生,方磊.动态预测软土路基沉降的神经网络模型研究[J].测绘科学,2008,33(6):110-112
[22]汪建斌,陈忠平.一种考虑荷载高度的沉降预测新方法[J].中外公路,2003,23(5):72-74.
[23]邵光辉.复合双曲线法预测公路沉降探讨[J].林业建设,2001(6):30–33.
[24]胡庆国,黄庆,黄生文.用实测资料求多极加载时软基沉降量的方法[J].湖南交通科技,1997,23(3):9–12.
[25]张仪萍,曹国强,李涛,张土乔.分级加载条件下沉降预测方法[J].中国公路学报,2005,18(1):30–33.
[26]刘松玉,经绯.软土地基上分期施工的路堤沉降预测方法[J].岩土工程学报, 2003, 25(2): 228–232.
[27]杨涛,李国维,杨伟清.基于双曲线法的分级填筑路堤沉降预测[J].岩土力学,2004,25(10):1551–1554.
[28]杨涛,戴济群,李国维.基于指数法的分级填筑路堤沉降预测方法研究[J].土木工程学报,2005, 38(5): 92–95.
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