综合管廊运行对临近能量支护排桩传热特性的影响

Influence of utility tunnel operation on thermal performance of adjacent energy sheet pile wall

该文针对综合管廊内空气对流换热对临近能量支护排桩传热特性的影响,通过在管廊内壁设置不同边界条件,建立三维有限元模型分析综合管廊运行对临近能量支护排桩传热特性的影响。通过将模拟结果与现场实测数据对比,验证模型的可靠性。探讨管廊内壁不同边界条件下能量支护排桩热交换率、桩-土换热量和桩体温度的变化规律。研究表明,管廊内空气对流换热会造成桩侧热交换和桩体温度的空间非对称性,从而影响能量支护排桩的地热提取效率。随着管廊内空气流速的增加,能量桩的地热提取效率逐渐增加,但当管廊内空气流速大于0.7m/s后,能量支护排桩的地热提取效率最终趋向于管廊内壁为恒定温度边界时的取值67.4W/m,管廊内壁采用恒定温度边界条件可作为能量支护排桩地热提取效率计算的上限,而采用热绝缘边界是偏于保守的。当管廊内壁采用已有研究提出的简化边界条件时,模型可以用于计算能量支护排桩的换热效率。

3⁃D finite element models were developed to investigate the effects of utility tunnel operation on the thermal response of an adjacent energy sheet pile wall,and influence of different boundary conditions on heat convection of air inside the utility tunnel was considered􀆰The models were validated by comparing the simulated results with the experimental results from a field test􀆰The heat exchange rate of energy sheet pile wall,heat flux and temperature on pile surface under different boundary conditions were analyzed􀆰The results show that the heat convection of the air inside the utility tunnel can influence the asymmetry distribution of heat flux,pile temperature,and the heat exchange rate of the energy pile􀆰The heat exchange rate of the energy pile incerases with the air velocity,but when the air velocity is larger than 0􀆰7m/s,the heat exchange rate of the energy sheet pile wall tends to the value of 67􀆰4W/m under constant temperature boundary condition of utility tunnel inner surface􀆰The constant temperature condition could be regarded as the upper limit of calculation of the heat exchange of energy sheet pile wall,while the boundary of thermal insulation is conservative􀆰When the simplified boundary for utility tunnel inner surface conducted in the previous study is adopted,the proposed model can be used to calculate the heat exchange rate of the energy sheet pile wall.