高速公路软土地基沉降反演与预测研究
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摘要
在软土地基上修建高速公路时，面临的主要问题是稳定和变形。由干路堤设计高度一般只有几米，稳定条件较易满足。所以，对于路堤工程，特别是对路面变形的要求非常严格的高速公路路堤工程，软土地基的沉降变形问题成为路堤建设的关键性土工技术问题。高速公路工后沉降的设计要求很高，相应对软土地基沉降的预测分析精度要求也很高，传统的计算方法已经无法满足这一要求。本文从影响路基沉降的不确定性因素出发，做了一些研究工作。
对于重要工程或重要地段的软土沉降反演计算，采用基于模型辨识的参数反演方法。根据模型辨识的原则和路基沉降的特点，把软土沉降计算模型的辨识分为二个层次：介质形态初步模型的辨识和最优模型的辨识。为了考虑软土次固结作用对软土地基后期影响，在传统考虑弹性、非线性弹性模型的模型类属集合中力口入了Merchant粘弹性模型。
对于一般工程的路基沉降计算，采用基于模型辨识的曲线拟合法。并且基于影响路基沉降分析的不确定性荷载因素，对车辆荷载及填土荷载逐级施加两种情况进行了量化分析：依据太沙基固结理论，推导了两种情况下的土层平均固结度公式，由此分析和讨论了不确定性荷载因素影响下路基固结的特性。在考虑填土荷载逐级施加情况的基础上，对指数法进行了改进。
结合徐宿高速公路，进行了基于模型识别的路基沉降反演预测和各类曲线拟合法预测工后沉降的计算，通过计算验证了模型识别反演预测思路和方法的适用性和改进指数法预测路基工后沉降的有效性和合理性。
The stability and deformation are the main problems for expressway constructed on the soft soil ground. The requirement of stability is easily reached, due to the design height of embankment is several meter. For embankment engineering of expressway, where the pavement deformation is strictly limited, the settlement of soft soil ground becomes the key engineering technique problem. The precision of the embankment's settlement forecast and analysis should be higher because the design of the expressway back-work settlement is exactly confined. Therefore, the traditional algorithm method can't meet the demands. Based on the uncertain factors affecting embankment's settlement, the paper makes some research work.
For important engineering or important embankment, the method of parameter inverse analysis based on model discerning is used to calculate the embankment's settlement. According to the principle of model discerning and the feature of embankment's settlement, the calculation model of soft soil ground's settlement is divided into the material discerning of the first model and the best model, In order to consider the soft soil ground's settlement affected by the secondly consolidation in the later stage, the Merchant visco-elastic model based on the elastic model and the non-linear-elastic model is adopted.
For the ordinary engineering, the curve fitting methods based on model discerning are introduced to calculate the embankment's settlement. On the basis of the uncertainty load factors which influence embankment's settlement, the vehicle load and the step-exert construction load are studied by quantity. According to the Terzaghi's consolidation theory, the average consolidation degree formulas of the corresponding situations are inferred. Moreover, the feature of the embankment's consolidation in the effect of uncertainty load factors is studied. At the same time, based on analyzing the step-exert construction load, the index method is improved.
The inverse analysis method based on model discerning and all these curve fitting methods are used to forecast settlement of Xuzhou-Suqian expressway after completing. The result from calculation and analyzed shows the thinking and the method in the paper are suitable, and it can be proved its rationality and feasibility in studying and forecasting settlement after construction of the embankment.
对于重要工程或重要地段的软土沉降反演计算，采用基于模型辨识的参数反演方法。根据模型辨识的原则和路基沉降的特点，把软土沉降计算模型的辨识分为二个层次：介质形态初步模型的辨识和最优模型的辨识。为了考虑软土次固结作用对软土地基后期影响，在传统考虑弹性、非线性弹性模型的模型类属集合中力口入了Merchant粘弹性模型。
对于一般工程的路基沉降计算，采用基于模型辨识的曲线拟合法。并且基于影响路基沉降分析的不确定性荷载因素，对车辆荷载及填土荷载逐级施加两种情况进行了量化分析：依据太沙基固结理论，推导了两种情况下的土层平均固结度公式，由此分析和讨论了不确定性荷载因素影响下路基固结的特性。在考虑填土荷载逐级施加情况的基础上，对指数法进行了改进。
结合徐宿高速公路，进行了基于模型识别的路基沉降反演预测和各类曲线拟合法预测工后沉降的计算，通过计算验证了模型识别反演预测思路和方法的适用性和改进指数法预测路基工后沉降的有效性和合理性。
The stability and deformation are the main problems for expressway constructed on the soft soil ground. The requirement of stability is easily reached, due to the design height of embankment is several meter. For embankment engineering of expressway, where the pavement deformation is strictly limited, the settlement of soft soil ground becomes the key engineering technique problem. The precision of the embankment's settlement forecast and analysis should be higher because the design of the expressway back-work settlement is exactly confined. Therefore, the traditional algorithm method can't meet the demands. Based on the uncertain factors affecting embankment's settlement, the paper makes some research work.
For important engineering or important embankment, the method of parameter inverse analysis based on model discerning is used to calculate the embankment's settlement. According to the principle of model discerning and the feature of embankment's settlement, the calculation model of soft soil ground's settlement is divided into the material discerning of the first model and the best model, In order to consider the soft soil ground's settlement affected by the secondly consolidation in the later stage, the Merchant visco-elastic model based on the elastic model and the non-linear-elastic model is adopted.
For the ordinary engineering, the curve fitting methods based on model discerning are introduced to calculate the embankment's settlement. On the basis of the uncertainty load factors which influence embankment's settlement, the vehicle load and the step-exert construction load are studied by quantity. According to the Terzaghi's consolidation theory, the average consolidation degree formulas of the corresponding situations are inferred. Moreover, the feature of the embankment's consolidation in the effect of uncertainty load factors is studied. At the same time, based on analyzing the step-exert construction load, the index method is improved.
The inverse analysis method based on model discerning and all these curve fitting methods are used to forecast settlement of Xuzhou-Suqian expressway after completing. The result from calculation and analyzed shows the thinking and the method in the paper are suitable, and it can be proved its rationality and feasibility in studying and forecasting settlement after construction of the embankment.
引文
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[8] Davis E. H. and Poulus H. G., The Use of Elastic Theory for Settlement Prediction under Three-dimensional Conditions, Geotechnique, 1968, 18(1):67～91
[9] Skempton A. W. and Bjerum L., A Contribution to the Settlement Analysis of Foundation on Clay, Geoteclmique, 1957, 7(4): 168～178
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materials, Proc Int Symp on Underground Engineering, Vol1, 1983
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[35] 谢宁，孙钧．上海地区饱和软粘土流变特性[J]．同济大学学报，1996，24(3)：233-237
[36] 占学钊．软土地区深基坑开挖变形分析及安全监测[D]．河海大学硕士学位论文，2003
[37] 沈珠江．理论土力学[M]，北京：中国水利水电出版社，2000
[38] 张学言．土塑性力学的建立与发展[J]．力学进展．1989,19(4)：485-495．
[39] 杨晖．车辆荷载作用下复合路基沉降研究的现状[J]．交通科技,2001(1)：46-47
[40] 凌建明，王伟等．行车荷载作用下湿软路基残余变形的研究[J]．同济大学学报，2002，30(11)：1315-1320
[41] 刘世君，岩石力学反演分析研究及工程应用[D]．河海大学博士学位论文，2003
[42] 赵维炳．软土固结与流变[M]．河海大学出版社，1996
[43] 刘世明，曾国熙．软粘土的次固结变形特性[J]．浙江大学学报，1990,24(6)：840-848
[44] 谭昌明，周建等．公路路堤软土地基沉降的二维反演与预测[J]．公路交通科技，2001，18(5)：11-14
[45] 殷宗泽，非线性及弹塑性比奥固结平面有限元程序[M]，河海大学，1988
[46] 郭志川．地基沉降的随机有限元法和可靠度计算[J]．土木工程学报，2001，34(5)：62-67
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[2] 折学森．软土地基沉降计算[M]．北京：人民交通出版社，
[3] 高大钊．土力学与基础工程[M]．北京：中国建筑工业出版社，1998
[4] Rendulic L. Porenziffer und Porenwasserdruck in Tonen. Bauingenieur, 1936, 7(51～53)
[5] Blot, M. A.. General theory of three-dimensional consolidation. J. of Applied Physics,Vol. 12, 155, 1941
[6] Gibson R. E., England G.L., Hussey M. J. H., The Theory of One-dimensional Consolidation of Saturated Clay(Ⅰ), Geotechnique, 1967, 17(3): 261～273
[7] 蔡正银等．自重应力作用下饱和粘土的固结特性[M]．岩土力学与工程的理论与实践，浙江大学出版社，1992
[8] Davis E. H. and Poulus H. G., The Use of Elastic Theory for Settlement Prediction under Three-dimensional Conditions, Geotechnique, 1968, 18(1):67～91
[9] Skempton A. W. and Bjerum L., A Contribution to the Settlement Analysis of Foundation on Clay, Geoteclmique, 1957, 7(4): 168～178
[10] 钱家欢、殷宗泽主编，土工原理与计算[M]，(第二版)，北京：水利电力出版社，1995
[11] Lambe T W, bjerrum L.A contribution to settlement analysis of foundation on Clay, 1957(7):168-178
[12] 日本道路协会编，蔡恩捷译．道路土工—软土地基处理技术指南[M]，北京：人民交通出版社，1984
[13] 张诚厚，袁文明，戴济群编著．高速公路软基处理[M]．北京：中国建筑工业出版社，1997
[14] 龚晓南．复合地基[M]．浙江：杭州大学出版社，1992
[15] Sandhu R S &Wilson E L.Finite Element Analysis of Seepage in Elastic Media,journal of Endineering Mechanics Division,ASCE,vil.95,1969
[16] 沈珠江．用有限元计算软土地基的固结变形[J]．水利水运科技情报，1977，4(1)：65-71
[17] Duncan J M, Chang C Y. nonlinear analysis of stress of strain insoils,J Soil Mech Found Div, ASCE, 1970,96(5): 1629-1653
[18] 谭昌明．高等级公路路堤软土地基沉降的反演与预测[D]．浙江大学博士学位论文，1999
[19] 罗昕．实测沉降的拟合和预测[D]．浙江大学硕士学位论文，2002
[20] 陈宝，马传明．珠江三角洲地区高速公路软基路堤工后沉降分析[J]．西部探矿工程，2003(6)：154-156
[21] Kavanagh K.And R.W. Clough, FiniteElement application in the characterization of elastic solids, Int. J.Solids Structure, 1971, Vo.1, 11-23
[22] 王芝银、李云鹏，地下工程围岩粘弹塑性参数反分析[J]．水利学报，1990(9)：31-34
[23] 杨志法、刘竹华，有限元图谱法的根据及其应用[J]．地下工程，1982(11)：24-28
[24] Cividini, Parameter estimation of a static geotechnical model using a Bayes' approach, Int J Rock mesh Min Sci&Geotech Abstr, Vol. 120,No.5, 1983.
[25] 吕爱钟、王永嘉，岩石力学反问题[M]，山东矿业学院出版社，1991．
[26] 杨林德等，岩土工程问题的反演理论与工程实践[M]，科学技术出版社，1995．
[27] Salcurai, Back analysis of measured displacements in shallow tunnel excavated in sandy
materials, Proc Int Symp on Underground Engineering, Vol1, 1983
[28] 刘允芳，弹性介质岩体中非圆形洞室位移反分析计算[J]．岩石力学和工程学报，1986(5)：43-46
[29] G.Gioda、S.Sakurai, Back analysis Procedure for the Interpretation of Field Measurements in Geomechanics, Int. J.for Num. and Analy Methods in Geomech, Vol.11, 1987:555-583
[30] 薛琳、杨志法，确定流变岩体的参数及地应力的位移反分析[J]．地质科学，1986(4)：5-8
[31] 龚晓南．反分析确定固结过程中土的力学参数[J]．浙江大学学报，1989(6)：841-848
[32] 康政虹．高等级公路软土路段路基沉降分析研究[D]．河海大学硕士学位论文，2003
[33] 黄文熙．土的工程性质[M]．北京：水利电力出版社，1983
[34] 章根德．土的本构关系及其工程应用[M]．北京：科学出版社，1995
[35] 谢宁，孙钧．上海地区饱和软粘土流变特性[J]．同济大学学报，1996，24(3)：233-237
[36] 占学钊．软土地区深基坑开挖变形分析及安全监测[D]．河海大学硕士学位论文，2003
[37] 沈珠江．理论土力学[M]，北京：中国水利水电出版社，2000
[38] 张学言．土塑性力学的建立与发展[J]．力学进展．1989,19(4)：485-495．
[39] 杨晖．车辆荷载作用下复合路基沉降研究的现状[J]．交通科技,2001(1)：46-47
[40] 凌建明，王伟等．行车荷载作用下湿软路基残余变形的研究[J]．同济大学学报，2002，30(11)：1315-1320
[41] 刘世君，岩石力学反演分析研究及工程应用[D]．河海大学博士学位论文，2003
[42] 赵维炳．软土固结与流变[M]．河海大学出版社，1996
[43] 刘世明，曾国熙．软粘土的次固结变形特性[J]．浙江大学学报，1990,24(6)：840-848
[44] 谭昌明，周建等．公路路堤软土地基沉降的二维反演与预测[J]．公路交通科技，2001，18(5)：11-14
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