多年冻土区宽幅路基温度场规律研究

发布时间：2018-10-12 16:26

【摘要】：随着公路事业的发展,高等级宽幅公路逐渐向青藏高原多年冻土区延伸。由于宽幅路基结构总吸热面积和总体积热容的增加以及全球气候变暖的影响,路基及基底多年冻土温度升高,冻土人为上限下移,路基结构易发生热融沉降变形。‘青藏高原多年冻土对温度敏感性大,EPS隔热层路基、碎(块)石路基和热棒路基等工程措施在现有道路工程中的应用效果较好,但是对于宽幅路基的处治效果还需要进一步研究讨论。本文以温度场的数值模拟结果为基础,对多年冻土区无工程措施的宽幅路基、隔热层宽幅路基以及隔热层与换填碎石复合路基的温度场分布特征进行研究分析,主要包括以下几个方面：论文首先基于多年冻土区路基温度场数值计算、模型参数以及边界条件的相关理论,结合青藏高原地区气候环境及多年冻土的特征,建立了路基温度场数值计算的控制方程,确定了土体的热物理参数以及边界条件,给出了多年冻土区路基温度场有限元数值模拟的理论基础、材料参数及边界条件。其次,在对比了不同宽度和高度的普通路基温度等值线图、地温沿深度随时间的变化曲线图以及年最大融深随时间的变化曲线图的基础之上,研究分析了路基的尺寸效应对路基温度场的影响规律,计算表明宽幅路基结构的热稳定性差,且路基越高,稳定性越好,并指出多年冻土区无工程措施的宽幅路基的合理填筑高度为4m-6m。第三,论文基于温度场的数值模拟结果,对隔热层路基的工程应用效果进行了研究分析,计算结果表明隔热层路基的热稳定性明显提高,且隔热层埋深越浅、厚度越大,温度稳定性越好,并根据保温效果和行车要求指出隔热层的合理厚度为0.15m-0.25m,合理埋深为0.5m-1.0m。最后,论文根据隔热层路基人为上限位置确定换填碎石层厚度,并对复合路基结构的保护效果进行数值模拟,并根据数值模拟结果提出隔热层与换填碎石复合路基的隔热层合理厚度与换填碎石合理深度的组合,隔热层厚度为0.08m-0.1m,换填碎石深度为3-5m。
[Abstract]:With the development of highway, high-grade wide-width highway extends to the permafrost area of Qinghai-Xizang Plateau. Because of the increase of the total heat absorption area and the total volume heat capacity of the broad embankment structure and the influence of global climate warming, the temperature of the embankment and its base permafrost increases, the artificial upper limit of the frozen soil moves down, and the subgrade structure is prone to thermal thawing settlement deformation. The permafrost of Qinghai-Xizang Plateau is highly sensitive to temperature, and the engineering measures such as EPS thermal insulation subgrade, broken (block) stone subgrade and hot bar subgrade have been applied well in existing road engineering. However, the treatment effect of wide embankment needs further study and discussion. Based on the numerical simulation results of temperature field, the temperature field distribution characteristics of broad embankment without engineering measures in permafrost region, wide embankment with thermal insulation layer and composite subgrade of heat-insulating layer and replacement gravel are studied and analyzed in this paper. The main contents are as follows: firstly, based on the numerical calculation of embankment temperature field in permafrost region, the theory of model parameters and boundary conditions, the climatic environment and permafrost characteristics of Qinghai-Xizang Plateau are combined. The governing equation of subgrade temperature field is established, the thermal physical parameters and boundary conditions of soil are determined, and the theoretical foundation, material parameters and boundary conditions of finite element numerical simulation of embankment temperature field in permafrost region are given. Secondly, on the basis of comparing the temperature isoline map of common roadbed with different width and height, the curve of variation of geothermal temperature along depth with time, and the curve of annual maximum melting depth with time, The influence of the size effect of the subgrade on the temperature field of the roadbed is studied and analyzed. The calculation shows that the thermal stability of the subgrade structure is poor, and the higher the roadbed is, the better the stability is. It is pointed out that the reasonable filling height of the broad embankment without engineering measures in permafrost region is 4m-6 m. Thirdly, based on the numerical simulation results of temperature field, the engineering application effect of the thermal insulation subgrade is studied and analyzed. The calculation results show that the thermal stability of the thermal insulation subgrade is obviously improved, and the shallower the thermal insulation layer is, the greater the thickness is. The better the temperature stability, according to the heat preservation effect and driving requirements, the reasonable thickness of thermal insulation layer is 0.15m-0.25m, and the reasonable buried depth is 0.5m-1.0m. Finally, according to the artificial upper limit position of the thermal insulation subgrade, the thickness of the replacement gravel layer is determined, and the protective effect of the composite subgrade structure is simulated numerically. According to the results of numerical simulation, the combination of reasonable thickness of insulation layer and reasonable depth of replacement crushed stone is put forward. The thickness of heat insulation layer is 0.08m-0.1m, and the depth of replacement gravel is 3-5m.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.168

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