路基宽度对多年冻土区透壁式通风管-块石复合路基降温效应的影响
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摘要
多年冻土区公路路基大多属高温冻土、极易受工程的影响产生融化下沉,多年冻土区宽幅公路聚热效应尤明显,路基宽度的增加会导致路基病害加重,路基稳定性问题已成为青藏道路工程建设亟待解决的关键问题。透壁式通风管-块石复合路基是一种主动降温措施。为研究其在宽幅公路的冷却效果及路基宽度的变化对路基降温效应的影响,基于块石层和通风管中空气的流速场和多孔介质传热的温度场的特征,采用两相物理场耦合关系,在考虑全球气候变暖以及路基两侧阴阳坡的条件下对宽幅公路透壁式通风管-块石复合路基的温度场进行数值模拟,分析路基施工后10年间的降温效应。研究结果表明:相较于素土路基,透壁式通风管-块石复合路基在路基下侧形成稳定冰核,对宽幅公路的冷却效果更为显著,宽度对路基的风速场和温度场影响明显。路基宽度增大,透壁式通风管风速减小,块石层风速增加,冰核面积及其下移深度增长速率变小,路基稳定时间加长,透壁式通风管-块石复合路基的降温效应逐渐减弱。当路基宽度大于32 m时,块石层风速增长速率明显放缓,低温区域面积增长速率及边缘深度下移增长速率下降,路基稳定时间延长,零温线上升高度减小。
The roadbeds in permafrost regions are mostly high-temperature frozen soils, which are highly susceptible to melting by engineering. The wide-area highways in permafrost regions have obvious heat-collecting effect, the increase of roadbed width will lead to aggravation of roadbed diseases. The stability of subgrade has become a key problem to be solved in the construction of Qinghai-Tibet road project. The composite roadbed which is composed of perforated ventilation ducts and crushed-rock layers is an active cooling measure. To study the cooling effect of wide highway and the influence of roadbed width on the cooling effect of roadbed, based on the characteristics of velocity filed of air flow in the crushed-rock layer and the ventilation duct as well as temperature field in heat transfer of porous media, adopting the two-phase physical field coupling relations, the numerical analysis on the temperature field of the composite roadbed with ventilated crashed rock layer of wide highway is carried out under sunny-shady slope boundaries and global warming condition to analyze the cooling effect of the roadbed after 10 years of construction. The result shows that(1) compared with the plain soil roadbed, the abovementioned composite roadbed forms a stable ice core on the lower side of the roadbed, the cooling effect on the wide highway is more significant, and the width has an obvious effect on the wind speed field and temperature field of the roadbed;(2) as the width increases, the wind speed in perforated ventilation duct decreases, the wind speed in crushed-rock layer increases,the growth rates of ice core area and its depth become slower, the stabilization time of roadbed becomes longer, and the cooling effect of the composite roadbed is gradually weakened;(3) when the roadbed width is greater than 32 m, the wind speed growth rate of crushed-rock layer is obviously slowed down, the growth rates of the low temperature area and the edge depth decrease, the roadbed stabilization time is prolonged, and the 0 ℃ line rise height is reduced.
The roadbeds in permafrost regions are mostly high-temperature frozen soils, which are highly susceptible to melting by engineering. The wide-area highways in permafrost regions have obvious heat-collecting effect, the increase of roadbed width will lead to aggravation of roadbed diseases. The stability of subgrade has become a key problem to be solved in the construction of Qinghai-Tibet road project. The composite roadbed which is composed of perforated ventilation ducts and crushed-rock layers is an active cooling measure. To study the cooling effect of wide highway and the influence of roadbed width on the cooling effect of roadbed, based on the characteristics of velocity filed of air flow in the crushed-rock layer and the ventilation duct as well as temperature field in heat transfer of porous media, adopting the two-phase physical field coupling relations, the numerical analysis on the temperature field of the composite roadbed with ventilated crashed rock layer of wide highway is carried out under sunny-shady slope boundaries and global warming condition to analyze the cooling effect of the roadbed after 10 years of construction. The result shows that(1) compared with the plain soil roadbed, the abovementioned composite roadbed forms a stable ice core on the lower side of the roadbed, the cooling effect on the wide highway is more significant, and the width has an obvious effect on the wind speed field and temperature field of the roadbed;(2) as the width increases, the wind speed in perforated ventilation duct decreases, the wind speed in crushed-rock layer increases,the growth rates of ice core area and its depth become slower, the stabilization time of roadbed becomes longer, and the cooling effect of the composite roadbed is gradually weakened;(3) when the roadbed width is greater than 32 m, the wind speed growth rate of crushed-rock layer is obviously slowed down, the growth rates of the low temperature area and the edge depth decrease, the roadbed stabilization time is prolonged, and the 0 ℃ line rise height is reduced.
引文
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[6] 田亚护,刘建坤,沈宇鹏. 青藏铁路多年冻土区热棒路基的冷却效果三维有限元分析[J].岩土工程学报,2013,35(增2):113-119. TIAN Ya-hu,LIU Jian-kun,SHEN Yu-peng. 3-D Finite Element Analysis of Cooling Effect of Qinghai-Tibet Railway Embankment with Thermosyphons in Permafrost Regions[J].Chinese Journal of Geotechnical Engineering. 2013,35(S2):113-119.
[7] 肖建章,赖远明,张学富,等. 青藏铁路旱桥的三维温度特性分析[J].冰川冻土,2004,26(4):426-434. XIAO Jian-zhang,LAI Yuan-ming,ZHANG Xue-fu,et al. Three-dimensional Temperature Character Analysis of the Land Bridge on the Qinghai-Tibet Railway[J]. Journal of Glaciology and Geocryology,2004,26(4):426-434.
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[9] 沈宇鹏,许兆义,王连俊,等. 路基宽度对多年冻土区站场路基温度场的影响[J].北京交通大学学报,2008,32(1):20-23.SHEN Yu-peng,XU Zhao-yi,WANG Lian-jun,et al. Influence of the Width of Station Embankment on Temperature Field in Permafrost Area[J]. Journal of Beijing Jiaotong University,2008,32(1):20-23.
[10] YU W B,LAI Y M,ZHANG X F. Laboratory Investigation on Cooling Effect of Coarse Rock Layer and Fine Rock layer in Permafrost Regions [J]. Cold Regions Science and Technology,2004, 38(3):31-42.
[11] 汪双杰,陈建兵. 青藏高原多年冻土路基温度场公路空间效应的非线性分析[J].岩土工程学报,2008,30(10):1544-1549.WANG Shuang-jie,CHEN Jian-bing. Nonlinear Analysis for Dimensional Effects of Temperature Field of Highway Embankment in Permafrost Regions on Qinghai-Tibet Plateau[J]. Chinese Journal of Geotechnical Engineering,2008,30(10):1544-1549.
[12] LAI Y M,GUO H X,DONG Y H. Laboratory Investigation on the Cooling Effect of the Embankment with L-shaped Thermosyphon and Crushed-rock Revetment in Permafrost Regions[J]. Cold Regions Science and Technology,2009,58(3):143-150.
[13] ZHANG M Y,LAI Y M,DONG Y H. Numerical Study on Temperature Characteristics of Expressway Embankment with Crushed-rock Revetment and Ventilated Ducts in Warm Permafrost Regions[J]. Cold Regions Science and Technology,2009,59(1):19-24.
[14] 刘戈,汪双杰,孙红,等. 透壁式通风管-块石复合路基降温效果模型试验及数值模拟[J]. 岩土工程学报,2015,37(2):284-291. LIU Ge,WANG Shuang-jie,SUN Hong,et al. Model Test and Numerical Simulation of Cooling Effect of Ventilated Duct-crashed Rock Composite Embankment[J]. Journal of Geotechnical Engineering,2015,37(2):284-291.
[15] NIU F J,SUN H, GE X R,et al. Temperature Adjustment Mechanism of Composite Embankment with Perforated Ventilation Pipe and Blocky Stone[J]. Journal of Shanghai Jiaotong University: Science, 2013, 18(6):729-732.
[16] 张坤,李东庆,童刚强. 通风管-块石复合路基降温效果的数值分析[J].中国矿业大学学报,2011,40(1):35-42.ZHANG Kun,LI Dong-qing, TONG Gang-qiang. Numerical Analysis of the Cooling Effect of an Embankment with Ventilated Ducts and Closed Block Stones[J]. Journal of China University of Mining & Technology,2011,40(1):35-42.
[17] JTG B01—2014,公路工程技术标准[S]. JTG B01—2014, Technical Standard of Highway Engineering[S].
[18] 何平,程国栋,马巍,等. 块石通风性能实验研究[J]. 岩土工程学报,2006,28(6):789-792.HE Ping,CHENG Guo-dong,MA Wei,et al. Researches on Ventilation Properties of Block Stones Layer[J]. Chinese Journal of Geotechnical Engineering,2006,28(6):789-792.
[2] 高宝林,孙志忠,董添春,等.青藏铁路路基下融化夹层特征及其对路基沉降变形的影响[J].冰川冻土,2015,37(1):126-131.GAO Bao-lin,SUN Zhi-zhong,DONG Tian-chun,et al. Characteristics of Thawed Interlayer beneath Embankment of the Qinghai-Tibet Railway in Permafrost Regions and Its Effect on Embankment Settlement Deformation[J]. Journal of Glaciology and Geocryology,2015,37(1):126 -131.
[3] 孙志忠,马巍,李东庆.青藏铁路北麓河试验段块石路基与普通路基的地温特征[J]. 岩土工程学报,2008,30(2):303-308.SUN Zhi-zhong,MA Wei,LI Dong-qing. Ground Temperature Characteristics of Block Stone Embankment and Traditional Embankment at Beiluhe along Qinghai-Tibet Railway[J]. Chinese Journal of Geotechnical Engineering,2008,30(2):303-308.
[4] 牛富俊,程国栋,李建军,等. 多年冻土区管道通风路基温度边界条件及温度场实测研究[J].冰川冻土,2006,28(3):386-389.NIU Jun-fu,CHENG Guo-dong,LI Jian-jun,et al. Experimental Study on the Thermal Boundary Conditions and Temperature Fields of Duct-ventilated Embankment in Permafrost Regions[J]. Journal of Glaciology and Geocryology,2006,28(3):386-389.
[5] 李国玉,李宁,康佳梅. 青藏铁路冻土区块石护坡路基热传递特性[J].冰川冻土,2007,29(2):315-321.LI Guo-yu,LI Ning,KANG Jia-mei. Heat Transfer Characteristics of the Embankment with Crushed-bock Slope Protection in Permafrost Regions along the Qinghai-Tibet Railway[J]. Journal of Glaciology and Geocryology,2007,29(2):315-321.
[6] 田亚护,刘建坤,沈宇鹏. 青藏铁路多年冻土区热棒路基的冷却效果三维有限元分析[J].岩土工程学报,2013,35(增2):113-119. TIAN Ya-hu,LIU Jian-kun,SHEN Yu-peng. 3-D Finite Element Analysis of Cooling Effect of Qinghai-Tibet Railway Embankment with Thermosyphons in Permafrost Regions[J].Chinese Journal of Geotechnical Engineering. 2013,35(S2):113-119.
[7] 肖建章,赖远明,张学富,等. 青藏铁路旱桥的三维温度特性分析[J].冰川冻土,2004,26(4):426-434. XIAO Jian-zhang,LAI Yuan-ming,ZHANG Xue-fu,et al. Three-dimensional Temperature Character Analysis of the Land Bridge on the Qinghai-Tibet Railway[J]. Journal of Glaciology and Geocryology,2004,26(4):426-434.
[8] LAI Y M,WANG Q S,NIU F J, et al. Three-dimensional Nonlinear Analysis for Temperature Characteristic of Ventilated Embankment in Permafrost Regions[J].Cold Regions Science and Technology,2004,38(2):165-184.
[9] 沈宇鹏,许兆义,王连俊,等. 路基宽度对多年冻土区站场路基温度场的影响[J].北京交通大学学报,2008,32(1):20-23.SHEN Yu-peng,XU Zhao-yi,WANG Lian-jun,et al. Influence of the Width of Station Embankment on Temperature Field in Permafrost Area[J]. Journal of Beijing Jiaotong University,2008,32(1):20-23.
[10] YU W B,LAI Y M,ZHANG X F. Laboratory Investigation on Cooling Effect of Coarse Rock Layer and Fine Rock layer in Permafrost Regions [J]. Cold Regions Science and Technology,2004, 38(3):31-42.
[11] 汪双杰,陈建兵. 青藏高原多年冻土路基温度场公路空间效应的非线性分析[J].岩土工程学报,2008,30(10):1544-1549.WANG Shuang-jie,CHEN Jian-bing. Nonlinear Analysis for Dimensional Effects of Temperature Field of Highway Embankment in Permafrost Regions on Qinghai-Tibet Plateau[J]. Chinese Journal of Geotechnical Engineering,2008,30(10):1544-1549.
[12] LAI Y M,GUO H X,DONG Y H. Laboratory Investigation on the Cooling Effect of the Embankment with L-shaped Thermosyphon and Crushed-rock Revetment in Permafrost Regions[J]. Cold Regions Science and Technology,2009,58(3):143-150.
[13] ZHANG M Y,LAI Y M,DONG Y H. Numerical Study on Temperature Characteristics of Expressway Embankment with Crushed-rock Revetment and Ventilated Ducts in Warm Permafrost Regions[J]. Cold Regions Science and Technology,2009,59(1):19-24.
[14] 刘戈,汪双杰,孙红,等. 透壁式通风管-块石复合路基降温效果模型试验及数值模拟[J]. 岩土工程学报,2015,37(2):284-291. LIU Ge,WANG Shuang-jie,SUN Hong,et al. Model Test and Numerical Simulation of Cooling Effect of Ventilated Duct-crashed Rock Composite Embankment[J]. Journal of Geotechnical Engineering,2015,37(2):284-291.
[15] NIU F J,SUN H, GE X R,et al. Temperature Adjustment Mechanism of Composite Embankment with Perforated Ventilation Pipe and Blocky Stone[J]. Journal of Shanghai Jiaotong University: Science, 2013, 18(6):729-732.
[16] 张坤,李东庆,童刚强. 通风管-块石复合路基降温效果的数值分析[J].中国矿业大学学报,2011,40(1):35-42.ZHANG Kun,LI Dong-qing, TONG Gang-qiang. Numerical Analysis of the Cooling Effect of an Embankment with Ventilated Ducts and Closed Block Stones[J]. Journal of China University of Mining & Technology,2011,40(1):35-42.
[17] JTG B01—2014,公路工程技术标准[S]. JTG B01—2014, Technical Standard of Highway Engineering[S].
[18] 何平,程国栋,马巍,等. 块石通风性能实验研究[J]. 岩土工程学报,2006,28(6):789-792.HE Ping,CHENG Guo-dong,MA Wei,et al. Researches on Ventilation Properties of Block Stones Layer[J]. Chinese Journal of Geotechnical Engineering,2006,28(6):789-792.