局部超低温制冷治理多年冻土路基融沉的数值模拟研究
|
摘要
青藏铁路路基在全球升温和人为施工热扰动等不利因素的影响下会出现融沉现象,针对多年冻土地区升温引发的路基融沉问题,提出了采用超低温短时制冷进行工程抢险和维护冻土路基稳定的方法。主要分析短时超低温制冷方法在不同的布管位置(路基和坡脚地层)、布管角度(水平管和倾斜管)、管长度(5 m、7 m)和制冷时间等因素影响下路基温度场、冻土上限和融化盘的变化。研究表明:超低温制冷方法是一种高效治理融沉灾害的抢险施工工法;管长越长冻土交圈时间越短,因为超低温的制冷效率高,可以在短时间内使路基处于负温状态,显著提高承载力;路基水平管的冻结效果好,坡脚处的冻结效果差;冻土上限可以在短时间内最高提升5 m,融化盘面积大大减少甚至可以被消除;路基内最高温度可以降低2℃,路基的最大融化深度可以降低4 m。综上所述,只要施工采取适宜的布管方式就可以在短时间内使整个路基处于负温状态,同时提高路基的承载力,达到很好的工程抢险效果。研究成果对治理多年冻土地区路基病害具有参考价值。
Thaw settlement of the subgrade of Qinghai Tibet Railway is to occur under the impacts from the global temperature rising and the thermal disturbance from artificial construction,thus a method for the relevant emergency construction and maintenance of the stability of the subgrade in permafrost soil zone with the short-time cryogenic refrigeration is proposed herein for the problem from the thaw-settlement of subgrade in the high temperature permafrost soil zone. The changes of the temperature field,frozen soil upper limit and thaw bowl under the influences from the factors,such as various positions of pipe layout(subgrade and slope toe stratum) various angles of pipe layout(horizontal pipe and inclined pipe),length of pipe(5 m and 7 m) and refrigeration time,are analyzed. The study result shows that the method of cryogenic refrigeration is an efficient emergency construction method for dealing with the thaw settlement hazard; for which the longer the pipe is,the shorter the frozen-soil enclosing time is to be. Because of the high refrigeration efficiency,the subgrade can be made into a condition of negative temperature in a short period of time,and then its bearing capacity is to be significantly enhanced. The refrigeration effect of the horizontal pipe inside the subgrade is better,while the effect at the slope toe is poorer. The upper limit of frozen soil can be increased by the highest of 5 m in a short period of time,while the area of the thaw bowl can be largely decreased and even eliminated. The maximum temperature inside the subgrade can be decreased by 2 ℃,while the maximum thawing depth can be decreased by 4 m as well. In conclusion,only the overall subgrade can be made into a negative temperature status by the pipe layout mode that is adaptable to construction,the bearing capacity of the subgrade can be enhanced along with a better effect of emergency construction. The study result has a referential value for the control of the engineering disease of the subgrade in permafrost soil zone.
Thaw settlement of the subgrade of Qinghai Tibet Railway is to occur under the impacts from the global temperature rising and the thermal disturbance from artificial construction,thus a method for the relevant emergency construction and maintenance of the stability of the subgrade in permafrost soil zone with the short-time cryogenic refrigeration is proposed herein for the problem from the thaw-settlement of subgrade in the high temperature permafrost soil zone. The changes of the temperature field,frozen soil upper limit and thaw bowl under the influences from the factors,such as various positions of pipe layout(subgrade and slope toe stratum) various angles of pipe layout(horizontal pipe and inclined pipe),length of pipe(5 m and 7 m) and refrigeration time,are analyzed. The study result shows that the method of cryogenic refrigeration is an efficient emergency construction method for dealing with the thaw settlement hazard; for which the longer the pipe is,the shorter the frozen-soil enclosing time is to be. Because of the high refrigeration efficiency,the subgrade can be made into a condition of negative temperature in a short period of time,and then its bearing capacity is to be significantly enhanced. The refrigeration effect of the horizontal pipe inside the subgrade is better,while the effect at the slope toe is poorer. The upper limit of frozen soil can be increased by the highest of 5 m in a short period of time,while the area of the thaw bowl can be largely decreased and even eliminated. The maximum temperature inside the subgrade can be decreased by 2 ℃,while the maximum thawing depth can be decreased by 4 m as well. In conclusion,only the overall subgrade can be made into a negative temperature status by the pipe layout mode that is adaptable to construction,the bearing capacity of the subgrade can be enhanced along with a better effect of emergency construction. The study result has a referential value for the control of the engineering disease of the subgrade in permafrost soil zone.
引文
[1] 孙志忠,武贵龙,贠汉伯,等. 多年冻土南界附近青藏铁路路基下的冻土退化[J].冰川冻土,2014,36(4);767- 771.
[2] 孙志忠,马巍,党海明,等. 青藏铁路多年冻土区路基变形特征及其来源[J]. 岩土力学,2013,34(9);2667- 2671.
[3] 马巍,刘端,吴青柏,等.青藏铁路冻土路基变形监测与分析[J]. 岩土力学,2008,29(3);571- 579.
[4] 程国栋.青藏高原多年冻土区路基工程地质研究[J].第四纪研究,2003,23(2);134- 141.
[5] 马巍,程国栋,吴青柏.多年冻土地区主动冷却地基方法研究[J].冰川冻土,2002,24(5);578- 587.
[6] 葛建军.青藏铁路多年冻土区保温护道路基温度场数值模拟研究[J].冰川冻土,2008,30(2):90- 95.
[7] 马立峰.牙林线多年冻土区路基冻融病害整治工程效果模拟[J].水文地质工程地质,2009,36(2):62- 66.
[8] 艾世勃,李君富.遮阳板与保温材料组合措施整治多年冻土地区路基病害数值分析[J]. 矿产勘查,2007(3):37- 41.
[9] 米隆,赖远明,吴紫汪,等.高原冻土铁路路基温度特性的有限元分析[J].铁道学报,2003,25(2);62- 67.
[10] 米隆,赖远明,张克华.冻土通风路基温度场的三维非线性分析[J].冰川冻土,2002,24(6);765- 769.
[11] 盛煜,刘永智,张建明,等.青藏公路多年冻土路基内的热状况[J].自然科学进展,2002,12(8);839- 844.
[12] 喻文兵,赖远明,牛富俊,等.多年冻土区铁路通风路基室内模型试验的温度场特性[J].冰川冻土,2002,24(5);601- 607.
[13] 牛富俊,程国栋,赖远明.青藏铁路通风路堤室内模型试验研究[J].西安工程学院学报,2002,24(3);1- 6.
[14] GOREING D J,INSTANES A,KUMA R P.Convective heat transfer in railway embankment ballast[C]//THIMUS J F.Ground Freezing 2000.Rotterdam,Netherlands:Balkema,2000: 31- 36.
[15] ZARLING J P,BILLY P E,CONNOR D J.Air duct systems for stabilization over permafrost area[C]//NAS. Proceeding of the 4th International Conference on Permafrost,Fairbanks. Washington,D.C.: National Academy Press,1983: 1463- 1468.
[2] 孙志忠,马巍,党海明,等. 青藏铁路多年冻土区路基变形特征及其来源[J]. 岩土力学,2013,34(9);2667- 2671.
[3] 马巍,刘端,吴青柏,等.青藏铁路冻土路基变形监测与分析[J]. 岩土力学,2008,29(3);571- 579.
[4] 程国栋.青藏高原多年冻土区路基工程地质研究[J].第四纪研究,2003,23(2);134- 141.
[5] 马巍,程国栋,吴青柏.多年冻土地区主动冷却地基方法研究[J].冰川冻土,2002,24(5);578- 587.
[6] 葛建军.青藏铁路多年冻土区保温护道路基温度场数值模拟研究[J].冰川冻土,2008,30(2):90- 95.
[7] 马立峰.牙林线多年冻土区路基冻融病害整治工程效果模拟[J].水文地质工程地质,2009,36(2):62- 66.
[8] 艾世勃,李君富.遮阳板与保温材料组合措施整治多年冻土地区路基病害数值分析[J]. 矿产勘查,2007(3):37- 41.
[9] 米隆,赖远明,吴紫汪,等.高原冻土铁路路基温度特性的有限元分析[J].铁道学报,2003,25(2);62- 67.
[10] 米隆,赖远明,张克华.冻土通风路基温度场的三维非线性分析[J].冰川冻土,2002,24(6);765- 769.
[11] 盛煜,刘永智,张建明,等.青藏公路多年冻土路基内的热状况[J].自然科学进展,2002,12(8);839- 844.
[12] 喻文兵,赖远明,牛富俊,等.多年冻土区铁路通风路基室内模型试验的温度场特性[J].冰川冻土,2002,24(5);601- 607.
[13] 牛富俊,程国栋,赖远明.青藏铁路通风路堤室内模型试验研究[J].西安工程学院学报,2002,24(3);1- 6.
[14] GOREING D J,INSTANES A,KUMA R P.Convective heat transfer in railway embankment ballast[C]//THIMUS J F.Ground Freezing 2000.Rotterdam,Netherlands:Balkema,2000: 31- 36.
[15] ZARLING J P,BILLY P E,CONNOR D J.Air duct systems for stabilization over permafrost area[C]//NAS. Proceeding of the 4th International Conference on Permafrost,Fairbanks. Washington,D.C.: National Academy Press,1983: 1463- 1468.