电加热对高寒隧道温度和损伤影响的数值研究

Numerical simulation study on the effect of electric heating on temperature and damage in high-altitude cold tunnels

摘要

【目的】高海拔寒区隧道工程在国家发展大环境下逐年增多，隧道洞口冻害普遍存在，现阶段防冻技术主要是被动保温防冻技术。【方法】基于此，建立高寒隧道电加热主动防护数值模型，分析不同环境温度下衬砌的受拉损伤以及电加热技术对于围岩冻胀和衬砌低温劣化的抑制效果，并探讨不同电热带发热功率、埋置深度、工作时间及保温板厚度等参数对防护效果的影响。【结果】研究结果表明：(1)隧道衬砌损伤随温度降低愈加严重，复合电加热技术可以有效解决低温损伤劣化问题；(2)随环境温度降低，高寒隧道电加热系统热功率增大；(3)电热带应铺设于高寒隧道衬砌表面，并配套使用厚度约5 cm的保温层效果较好；(4)隧道衬砌温度随环境温度变化具有滞后性，建议在寒季开始前约15天左右开启电加热系统，提前7天关闭系统。【结论】电加热技术在隧道保温防冻中能极大程度提高保温防冻效果，不同环境温度下所需的电加热系统功率不同。通过对电加热进行参数化分析，提出合理的施工建议，以指导电加热技术在隧道工程中的应用。

Abstract

[Objective] Tunnel projects in high-altitude cold areas are increasing year by year under the national development environment. Tunnel opening frost damage is widespread, and at this stage, the frost protection technology is mainly passive thermal insulation and frost protection technology. [Methods] Based on this, a numerical model of electric heating active protection for high-altitude cold tunnels is established. The tensile damage of the lining under different ambient temperatures, the inhibition effect of electric heating technology on the freezing of the surrounding rock, and the low-temperature deterioration of the lining are analyzed. And the influence of different electric heating power, burial depth, working time, and thickness of insulation board on the protection effect are explored. [Results] The result of the study show that:(1) The damage of tunnel lining becomes more and more serious with the decrease of temperature. Composite electric heating technology can effectively solve the problem of low-temperature damage deterioration;(2) With the lowering of the ambient temperature, the thermal power of the electric heating system of the alpine tunnel increases;(3) Electric heating tape should be laid on the surface of the alpine tunnel lining, and supporting the use of a thickness of about 5 cm of the thermal insulation layer is more effective;(4) The tunnel lining temperature with the change in the ambient temperature with hysteresis. It is recommended to switch on the electric heating system about 15 days before the start of the cold season, and switch off the system 7 days in advance. [Conclusion] Electric heating technology in tunnel insulation and frost protection can greatly improve the effect of insulation and frost protection. Different ambient temperatures require different power of the electric heating system. Through the parametric analysis of electric heating, reasonable construction recommendations are made to guide the application of electric heating technology in tunnel engineering.

关键词

隧道工程 / 高海拔寒区 / 数值计算 / 电加热技术 / 低温损伤

Key words

tunneling / high altitude cold region / numerical calculation / electric heating technology / low-temperature damage

基金资助

国家自然科学基金区域创新发展联合基金(U21A20152)

国家自然科学基金面上项目(52278416)