【作者】 李小和；

【导师】 魏庆朝；

【作者基本信息】 北京交通大学 ， 道路与铁道工程， 2009， 博士

【摘要】 冻土区路基工程的修建,在改变原来天然地面的散热特征和多年冻土季节融化层水热输运特征的同时,作为横垣地面的连续线型结构物,还极大地改变了原有的地表水热环境特征,使路基修筑以后形成的新结构物与周围环境开始了新的二维传热过程,伴随这种传热过程的土体变形对路基工程裂缝的发生和发展起了很重要的作用。青藏铁路开通工程列车后,列车振动荷载的介入增加了新的影响因素,使路基工程裂缝的发生发展过程更加复杂。2001年开工建设的青藏铁路冻土试验工程经过一个冻融循环后,路基不同部位出现了工程裂缝,其后不同阶段也陆续出现了一些不同程度的工程裂缝。研究不同阶段冻土区路基工程裂缝的发生机理、工程对策,对保证今后青藏铁路冻土区线路长期安全运营具有重要应用价值。本文以青藏铁路冻土区路基工程裂缝为研究对象,以经典冻土学理论和国内外对路基工程裂缝理论认识及研究成果为基础,进行了以下几个方面的研究:1、通过现场调查初步明确了影响冻土区路基工程裂缝的工程地质条件、环境地质条件和水热环境条件等主要因素,分析了工程修建引起的水热环境变化,提出了控制影响路基工程裂缝的人为水热环境应注意的问题。2、结合青藏铁路工程实际,对冻土区路基修建后不同时期出现的不同部位和形态的路基工程裂缝,从传热学角度,即从路基土体冷生过程的角度对工程裂缝发展进行了阶段划分,研究了不同阶段路基工程裂缝发展的特征,分析了不同阶段影响路基工程裂缝的不同因素和发生部位。3、通过对路基地温场、变形观测、裂缝发生及发展的形态变化的实际观测,从土质学机理、冻土冷生机理和水热环境影响机理三个方面对路基工程裂缝的发生机理进行了研究,针对不同阶段冻土区路基工程裂缝的发生机理和发展过程,提出整治裂缝的工程对策。4、针对防治路基开裂典型工程对策的长期效果进行了数值计算模拟和分析,结合实际观测结果对防止裂缝和整治裂缝的技术关键和工程管理提出可供实践的意见。更多还原

【Abstract】 Constructions of roadbed in permafrost areas have changed the thermal distinction of original natural ground surface and the distinction of water-heat transportation within seasonal thawing layer of permafrost,as well as the water-heat environmental distinction of original ground surface.All these changes have led to a new two-dimensional heat-transfer process between the new structures and the environment at both vertical and horizontal directions.Roadbed deformation associated with such heat-transfer process influences the occurrence and development of crack of roadbed. After the permafrost roadbed construction of Qinghai-Tibet railway completion, vibrating load from the constructional trains made the mechanical expression of the new heat-transfer process more complex.The permafrost test roadbed construction of Qinghai-Tibet railway was built in 2001 and cracks occurred at different places of roadbed after first cycle of freezing and thawing.It is valuable to study the mechanics and engineering solutions to ensure the safety of long-period operation of Qinghai-Tibet railway.Based on classic theory of cryopedology and research achievements of roadbed cracks,the crack of Qinghai-Tibet railway roadbed was studied in this dissertation.Its main contents are generalized as follows.1.Engineering geological conditions,environmental geological conditions and water-heat environmental conditions were determined as influential factors of crack occurrence by field survey.Changes of water-heat environmental conditions caused by roadbed construction were analyzed,and key problems that control the crack of roadbed were presented.2.Cracks were classified according to its location and shape.Distinctions of different development stages of roadbed crack were studied.Also influential factors and occurrence locations were analyzed.3.The mechanics of occurrence of roadbed cracks was studied from phases of soil mechanics,permafrost cooling mechanics and water-heat environmental influence mechanics by field survey of ground temperature field,roadbed deformation and the development of crack shape.Regulating measures were presented.4.Numerical simulation was accomplished to evaluate the long-period effect of regulating measures for cracks.Finally key preventive and regulating techniques and suggestions were presented.更多还原