重载交通水泥混凝土路面材料与结构研究
|
摘要
重载交通现象是世界范围内普遍存在的问题,已引起国内外道路工作者的关注,并对此进行了许多尝试性和探讨性的研究。本文从材料与结构两方面对重载交通水泥混凝土路面修筑技术进行了深入研究。
(1) 在分析重载交通条件下水泥混凝土路面损坏特征及其机理的基础上,从材料与结构方面提出了防止或者减少冲刷破坏、疲劳破坏和磨损等措施。针对冲刷破坏,比较有效的途径是设置传力杆和路面内部排水系统,以及采用耐冲刷的高模量基层材料,如贫混凝土基层和水泥稳定碎石基层;针对早期疲劳破坏,问题解决的途径有两条:一是在现有设计抗折强度5.0MPa基础上,增加面板厚度;二是在基本不增加板厚的基础上,提高路面的设计抗折强度,以提高路面板抵抗重轴载疲劳破坏的能力。
(2) 为了增强有限路面厚度抵抗重轴载破坏的能力,降低原材料消耗及水化热,对基于重载交通的高性能路面混凝土(High Performance Pavement Concrete,简称HPPC)进行了系统深入的研究,提出了具有优良路用性能的HPPC组成设计方法及施工工艺。
(3) 现行规范中基顶当量回弹模量换算方法是建立在弯沉等效基础之上的,这种方法掩盖了半刚性基层的特性,尤其是重载交通水泥混凝土路面下的高模量基层特性,使得荷载应力和温度应力计算值出现较大的偏差。本文在大量计算基础上,分别建立了以板底拉应力和温度翘曲应力为等效原则的基顶当量回弹模量换算方法。
(4) 现行规范中双层板荷载应力分析仍采用了弹性薄板基本假设,未能考虑双层板的竖向压缩和横向剪切变形,过分扩大了基层的支撑作用,致使计算结果出现较大的偏差。本文在大量计算的基础上,建立了双层板荷载应力实用计算方法。
(5) 为了便于应用及避免查用诺谟图时出现偏差,本文针对通用的设计条件进行大量的有限元分析,根据计算结果建立了具有较高精度的温度翘曲应力系数和温度应力系数的经验公式。
(6) 温度变化对接缝传荷效能的影响较大,负温度梯度的作用有利于降低板边挠度值,而对于特定路面结构,传荷系数是温度和时间的函数。在计算临界荷位处温度应力和荷载应力时可不考虑传力杆的影响,对纵缝设拉杆时建议在计算温度应力时引入拉杆修正系数(k_(tr)=1.02～1.05)。
(7) 有限元分析表明,轮载或者温度变化作用下传力杆/混凝土界面存在明显应力集中现象,致使界面处容易形成初始裂缝和挤碎,使传力杆松动量增大,降低传荷能力,甚至导致接缝损坏。传力杆装置改进的初步研究表明,保护套能有效减少传力杆/混凝土界面处应力集中现象,提高接缝传荷能力的耐久性,并讨论了保护套的设计及制作方法。
(8) 通过对重载交通特性、材料性能与结构组合等方面的研究,及对现有重载交通水泥混凝土路面使用状况、破损机理等综合分析,在广泛搜集有关资料的基础上,提出了重载交通路面结构组合的原则,并给出了重载交通水泥混凝土路面的典型结构。
The heavy-load transportation is a worldwide problem, which has come to attention at home and abroad and has been researched. In this study, the construction techniques of cement concrete pavement under heavy-load transportation were researched from the two aspects of materials and makeup of pavement.1. The characteristic and mechanism of initial failures on cement concrete pavements underheavy-load transportation have been analyzed in this paper. Based on this, the countermeasure against cement concrete pavement destroying was addressed herein from pavement's material and makeup. Setting dowel in concrete transverse joints and pavement structural drainage system, choosing the base material of good performance at aspect of anti-pumping, can effectively prevent pavements pumping damages; Increasing the thickness or raising the flexure strength of concrete slab can prevent the initial fatigue failures.2. In order to building up anti-destroying capability of the given pavement thickness under heavy load, reducing the wastes of raw and processed materials, the high performance pavement concrete, which has a very good road performances, was developed applying to cement concrete pavement under heavy-load transportation.3. The calculation method of composite resilient modulus of foundation in present specification of cement concrete pavement design for highway is based on the principles of the deflections equivalency at the top of base. The method can't reflect the characteristics of large rigidity of semi-rigid base, which results in the very larger difference between a loading or thermal stresses computed value and a theoretically correct value. In this study, the calculation method of composite resilient modulus of foundation was founded on the equivalent principles of the flexure stresses of concrete slabs and stresses induced concrete slab due to thermally warped or curled.4. Concrete slabs was assumed to be an infinite thin plate resting on elastic foundation, when loading stresses in double-layered plain concrete pavements adopted in present specification of cement concrete pavement design for highway are analyzed. The assumption can't calculate the vertical compressing deflection and the level cutting deflection, and exaggerates the function of base supporting. This brings about the error of loading stresses computed value in double-layered plain concrete pavements. The applied calculation method of loading stresses in double-layered plain concrete pavements was founded in the study5. For the sake of convenient for application and avoiding consulting a nomogram for
thermal stresses calculation, through a great deal of calculation for different pavement construct, this paper presents experiential formula for the coefficient of thermal stresses, which has precision in use.6. The results indicated that the influence of temperature variations on load transfer efficiency is very large, application of negative temperature gradient make for reducing deflections at joints and LTE of a specific pavement is time dependant. The influence of dowel bars at transverse joints on loading stresses and thermal stresses at the critical load position can be ignored, and the influence coefficient of dowel bars at longitudinal joints on thermal stresses is 1.02— 1.05.7. In this study, three dimensional finite element models were developed simulating stressesinduced in doweled joints due to thermal and load. The results indicate that excessive contact stresses at the interfaces between steel dowels and the surrounding concrete occurs due to thermal and load, and crack at dowel/concrete interface form. This leads to the development of dowel looseness and distress in concrete transverse joints. New load-transferring device pilot studies indicate that the protecting sleeves significantly reduce the magnitude of such contact stresses and enhance durability of load transfer efficiency. Finally, this paper presents the design method of the protecting sleeves.8. Based on analysis of pavement condition and damaged mechanism on cement concretepavements under heavy-load transportation, according to research of the characteristic of heavy-load transportation, material properties and structural composition design of cement concrete pavement, this paper presents the principia of structural composition design and the typical structure of cement concrete pavement under heavy-load transportation9. Considering the failures characteristic on cement concrete pavements under heavy-load transportation, in this study, a design method of concrete pavements, which aims for preventing concrete pavement fatiguing and pumping distress and destroying under the once or more effect of loads, is primarily put forward.
(1) 在分析重载交通条件下水泥混凝土路面损坏特征及其机理的基础上,从材料与结构方面提出了防止或者减少冲刷破坏、疲劳破坏和磨损等措施。针对冲刷破坏,比较有效的途径是设置传力杆和路面内部排水系统,以及采用耐冲刷的高模量基层材料,如贫混凝土基层和水泥稳定碎石基层;针对早期疲劳破坏,问题解决的途径有两条:一是在现有设计抗折强度5.0MPa基础上,增加面板厚度;二是在基本不增加板厚的基础上,提高路面的设计抗折强度,以提高路面板抵抗重轴载疲劳破坏的能力。
(2) 为了增强有限路面厚度抵抗重轴载破坏的能力,降低原材料消耗及水化热,对基于重载交通的高性能路面混凝土(High Performance Pavement Concrete,简称HPPC)进行了系统深入的研究,提出了具有优良路用性能的HPPC组成设计方法及施工工艺。
(3) 现行规范中基顶当量回弹模量换算方法是建立在弯沉等效基础之上的,这种方法掩盖了半刚性基层的特性,尤其是重载交通水泥混凝土路面下的高模量基层特性,使得荷载应力和温度应力计算值出现较大的偏差。本文在大量计算基础上,分别建立了以板底拉应力和温度翘曲应力为等效原则的基顶当量回弹模量换算方法。
(4) 现行规范中双层板荷载应力分析仍采用了弹性薄板基本假设,未能考虑双层板的竖向压缩和横向剪切变形,过分扩大了基层的支撑作用,致使计算结果出现较大的偏差。本文在大量计算的基础上,建立了双层板荷载应力实用计算方法。
(5) 为了便于应用及避免查用诺谟图时出现偏差,本文针对通用的设计条件进行大量的有限元分析,根据计算结果建立了具有较高精度的温度翘曲应力系数和温度应力系数的经验公式。
(6) 温度变化对接缝传荷效能的影响较大,负温度梯度的作用有利于降低板边挠度值,而对于特定路面结构,传荷系数是温度和时间的函数。在计算临界荷位处温度应力和荷载应力时可不考虑传力杆的影响,对纵缝设拉杆时建议在计算温度应力时引入拉杆修正系数(k_(tr)=1.02～1.05)。
(7) 有限元分析表明,轮载或者温度变化作用下传力杆/混凝土界面存在明显应力集中现象,致使界面处容易形成初始裂缝和挤碎,使传力杆松动量增大,降低传荷能力,甚至导致接缝损坏。传力杆装置改进的初步研究表明,保护套能有效减少传力杆/混凝土界面处应力集中现象,提高接缝传荷能力的耐久性,并讨论了保护套的设计及制作方法。
(8) 通过对重载交通特性、材料性能与结构组合等方面的研究,及对现有重载交通水泥混凝土路面使用状况、破损机理等综合分析,在广泛搜集有关资料的基础上,提出了重载交通路面结构组合的原则,并给出了重载交通水泥混凝土路面的典型结构。
The heavy-load transportation is a worldwide problem, which has come to attention at home and abroad and has been researched. In this study, the construction techniques of cement concrete pavement under heavy-load transportation were researched from the two aspects of materials and makeup of pavement.1. The characteristic and mechanism of initial failures on cement concrete pavements underheavy-load transportation have been analyzed in this paper. Based on this, the countermeasure against cement concrete pavement destroying was addressed herein from pavement's material and makeup. Setting dowel in concrete transverse joints and pavement structural drainage system, choosing the base material of good performance at aspect of anti-pumping, can effectively prevent pavements pumping damages; Increasing the thickness or raising the flexure strength of concrete slab can prevent the initial fatigue failures.2. In order to building up anti-destroying capability of the given pavement thickness under heavy load, reducing the wastes of raw and processed materials, the high performance pavement concrete, which has a very good road performances, was developed applying to cement concrete pavement under heavy-load transportation.3. The calculation method of composite resilient modulus of foundation in present specification of cement concrete pavement design for highway is based on the principles of the deflections equivalency at the top of base. The method can't reflect the characteristics of large rigidity of semi-rigid base, which results in the very larger difference between a loading or thermal stresses computed value and a theoretically correct value. In this study, the calculation method of composite resilient modulus of foundation was founded on the equivalent principles of the flexure stresses of concrete slabs and stresses induced concrete slab due to thermally warped or curled.4. Concrete slabs was assumed to be an infinite thin plate resting on elastic foundation, when loading stresses in double-layered plain concrete pavements adopted in present specification of cement concrete pavement design for highway are analyzed. The assumption can't calculate the vertical compressing deflection and the level cutting deflection, and exaggerates the function of base supporting. This brings about the error of loading stresses computed value in double-layered plain concrete pavements. The applied calculation method of loading stresses in double-layered plain concrete pavements was founded in the study5. For the sake of convenient for application and avoiding consulting a nomogram for
thermal stresses calculation, through a great deal of calculation for different pavement construct, this paper presents experiential formula for the coefficient of thermal stresses, which has precision in use.6. The results indicated that the influence of temperature variations on load transfer efficiency is very large, application of negative temperature gradient make for reducing deflections at joints and LTE of a specific pavement is time dependant. The influence of dowel bars at transverse joints on loading stresses and thermal stresses at the critical load position can be ignored, and the influence coefficient of dowel bars at longitudinal joints on thermal stresses is 1.02— 1.05.7. In this study, three dimensional finite element models were developed simulating stressesinduced in doweled joints due to thermal and load. The results indicate that excessive contact stresses at the interfaces between steel dowels and the surrounding concrete occurs due to thermal and load, and crack at dowel/concrete interface form. This leads to the development of dowel looseness and distress in concrete transverse joints. New load-transferring device pilot studies indicate that the protecting sleeves significantly reduce the magnitude of such contact stresses and enhance durability of load transfer efficiency. Finally, this paper presents the design method of the protecting sleeves.8. Based on analysis of pavement condition and damaged mechanism on cement concretepavements under heavy-load transportation, according to research of the characteristic of heavy-load transportation, material properties and structural composition design of cement concrete pavement, this paper presents the principia of structural composition design and the typical structure of cement concrete pavement under heavy-load transportation9. Considering the failures characteristic on cement concrete pavements under heavy-load transportation, in this study, a design method of concrete pavements, which aims for preventing concrete pavement fatiguing and pumping distress and destroying under the once or more effect of loads, is primarily put forward.
引文
1.王振清.公路超限运输概论.人民交通出版社,1997.
2.山西省交通科学研究院、同济大学.承受特重车辆作用的水泥混凝土路面应力分析研究报告,2001.
3.刘颖.重载道路路面设计方法研究.长安大学硕士学位论文,2001年.
4.张海斌.重载作用下路用材料特性及设计参数研究.长安大学硕士学位论文,2001年.
5.河南省许昌市公路管理局,长安大学.重载交通水泥混凝土路面材料与结构研究报告,2003年12月.
6. Ioannides, A. M., and Donnelly, J. P. (1988), Three-dimensional analysis of slab on stress dependent foundation. Transportation research record 1196, TRB, National research council, Washington, D. C., pp. 72-84.
7. Analytical Modeling of Rock-Structure Interaction, (1973), Volumes 1-3. Reports AD-761-648, 649, 650, Advanced Research Projects Agency of U.S.Department of Defenseand U.S.Bureau of Mines.
8. ASCE Report card on America's Infrastructures (2001).
9. The AASHTO road test-Pavement research (1962). Special report 61E, Highway Research Board.
10. Channakeshava, C., Barzegar, F., and Voyiadjis, G. (1993). Nonlinear finite lement analysis of plain concrete pavement with doweled joints. Journal of transportationengineering, 199(5).
11. Chatti, K., Lysmer, J., and Monismith, C.L. (1994), Dynamic finite element analysis of jointed concrete pavements. Transportation research record 1449, TRB, 12.
12. National research council, Washington, D. C..
13. Grant M. The World of Rome, 1960.
14.陈志华.外国建筑史.中国工业出版社,1962.
15.Neville A M.混凝土的性能.中国建筑工业出版社,1983.
16. Mindess S、Young J F. Concrete. Prentice—Hall INC. Englewood Cliffs, Newjersey, 1981
17.吴中伟、廉慧珍.高性能混凝土.中国铁道出版社,1999.
18.中华人民共和国交通部.《公路水泥混凝土路面设计规范》(JTG D40-2002).人民交通出版社,2002
19.田波.重载水泥混凝土路面结构分析.同济大学博士学位论文,2001
20.赵炜诚.重载作用下贫混凝土基层混凝土路面设计方法初步研究.同济大学博士学位论文,2003
2.山西省交通科学研究院、同济大学.承受特重车辆作用的水泥混凝土路面应力分析研究报告,2001.
3.刘颖.重载道路路面设计方法研究.长安大学硕士学位论文,2001年.
4.张海斌.重载作用下路用材料特性及设计参数研究.长安大学硕士学位论文,2001年.
5.河南省许昌市公路管理局,长安大学.重载交通水泥混凝土路面材料与结构研究报告,2003年12月.
6. Ioannides, A. M., and Donnelly, J. P. (1988), Three-dimensional analysis of slab on stress dependent foundation. Transportation research record 1196, TRB, National research council, Washington, D. C., pp. 72-84.
7. Analytical Modeling of Rock-Structure Interaction, (1973), Volumes 1-3. Reports AD-761-648, 649, 650, Advanced Research Projects Agency of U.S.Department of Defenseand U.S.Bureau of Mines.
8. ASCE Report card on America's Infrastructures (2001).
9. The AASHTO road test-Pavement research (1962). Special report 61E, Highway Research Board.
10. Channakeshava, C., Barzegar, F., and Voyiadjis, G. (1993). Nonlinear finite lement analysis of plain concrete pavement with doweled joints. Journal of transportationengineering, 199(5).
11. Chatti, K., Lysmer, J., and Monismith, C.L. (1994), Dynamic finite element analysis of jointed concrete pavements. Transportation research record 1449, TRB, 12.
12. National research council, Washington, D. C..
13. Grant M. The World of Rome, 1960.
14.陈志华.外国建筑史.中国工业出版社,1962.
15.Neville A M.混凝土的性能.中国建筑工业出版社,1983.
16. Mindess S、Young J F. Concrete. Prentice—Hall INC. Englewood Cliffs, Newjersey, 1981
17.吴中伟、廉慧珍.高性能混凝土.中国铁道出版社,1999.
18.中华人民共和国交通部.《公路水泥混凝土路面设计规范》(JTG D40-2002).人民交通出版社,2002
19.田波.重载水泥混凝土路面结构分析.同济大学博士学位论文,2001
20.赵炜诚.重载作用下贫混凝土基层混凝土路面设计方法初步研究.同济大学博士学位论文,2003