【作者】 赖金星；

【导师】 谢永利；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2008， 博士

【摘要】 鉴于复杂地质条件下高海拔地区特长公路隧道温度场特征及结构性能研究不足的现状,论文依托青藏高原东部青沙山公路隧道工程,通过对结构受力和温度场的大规模现场测试、基于有限元理论的数值模拟及理论分析等手段对高海拔地区公路隧道力学性状进行了系统研究,为依托工程设计施工及防冻保温提供了有效指导。1.针对依托工程特点,开展了大规模的围岩位移和结构受力性状现场测试。分析了围岩位移特性,根据围岩位移进行反分析得出了后续数值模拟所需参数。结构受力性状测试表明:隧道洞口段受冻胀力作用,其峰值位置在边墙底部与仰拱相交处,隧道洞口段边墙和仰拱支护应加强,隧道运营期间冻胀力有增加趋势;依托工程最冷月份平均气温为-11.2℃,规范规定低于-15℃时应考虑冻胀力的结论值得商榷。2.鉴于高海拔地区隧道温度场特征研究的不足,开展了系统的环境温度与地温场测试与分析。得出了环境温度变化规律及温度场数值模拟的荷载条件。地温场测试表明:隧道洞口附近与洞内地温梯度不同,地温场受环境温度、自然风、地质条件和地下水的影响较大;洞内地温随着围岩深度的加深而增加;围岩内隧道径向存在某一比较稳定的温度边界条件,隧道内初始温度场也为某一固定值,可作为温度场数值模拟的初始边界条件;隧道运营期间,因“活塞”效应风速增大,冷能入侵加剧,洞内环境温度下降,洞内地温下降。3.基于温度场测试成果,将隧道内环境实测温度作为载荷施加到隧道二衬混凝土表面,采用非稳态带相变的热传导有限元方法对温度场进行数值模拟,对隧道一般埋深横断面和隧道纵向进行有、无保温隔热层的数值分析,确定了隧道内保温隔热层厚度和沿隧道纵向铺设长度,推荐了外贴式防冻保温结构型式。采用温度-应力耦合有限元模型计算了50a冻螎循环下洞口段冻胀力,并与弹性力学公式和测试结果进行了对比分析。4.根据依托工程复杂地质条件特点,建立了有效的数值计算模型,着重研究了力学参数敏感性、断层破碎带隧道稳定性、偏压条件下进洞施工方法的合理性、洞口段长管棚预支护力学性状、滑动面与隧道轴线大角度相交时隧道开挖对含抗滑桩边坡稳定性影响。5.提出了简捷适用的支护强度发挥度概念,根据系统的围岩压力测试成果,采用研编荷载结构模型程序对依托工程长期安全性和支护强度发挥度进行了分析。结果表明:实测围岩压力作用下结构处于安全状态,VI级围岩测试断面最合理,V级围岩测试断面最不合理;冻胀力作用下,VI、V级围岩测试断面安全系数最小值满足规范要求。更多还原

【Abstract】 In view of poor theory research on structure characteristics and temperature field for cold-region road tunnels with complex geological conditions, Based on the cold-region tunnel named Qingshashan in Qinghai province, located in the east of Qinghai-Tibet plateau, serving engineering are regarded as the capital objective, through in-situ test, numerical simulation which based on FEM theory and theory analysis, mechanical characteristics of cold-region road tunnels with complex geological conditions were studied systemically.1.According to the characteristics of depending engineering, The in-situ test was synthetically taken to disclosure regularity of displacement of surrounding rock and mechanical characteristics of support structure. In-situ test results show that lining in opening of the tunnel loaded by frozen-heave force. The maximum frozen-heave force is located at crossing position between sidewall and invert. So crossing position between sidewall and invert should be reinforced. Average temperature of the depending tunnel during the coldest month is -11.2℃, while according to the code for Design of road tunnel(JTG D70-2004) frozen-heave force should be considered when average temperature of the tunnel during the coldest month less than -15℃, So the conclusion of the code should be re-determined.2.Based on the cold-region tunnel named Qingshashan, a one-way and double lane tunnel with disjunctive up and down lines,14 sections were set up to observe the ground temperature with resistance method of temperature determination. The distribution characters of the ground temperature versus time and space were studied. It is found that, 1) Ground temperature field is influenced by air temperature, nature wind, geological conditions and seepage of groundwater. 2) Maximum of negative air temperature and maximum frozen depth is not at the same section.3) with increasing of depth the ground temperature increases. 4) The temperature gradient of outer tunnel is different from inner tunnel. The obtained conclusions can guide the construction and design of tunnel in cold regions.3.According to the in-situ test results of temperature, by FEM with phase change the temperature fields of tunnel with insulation and without insulation are calculated and analyzed. The thickness and length of heat insulation layer are obtained, then insulation structure layed out of the lining is taken. By coupled FEM of temperature and stress frozen-heave force was researched under 50a freeze-thaw circulate. The results of in-situ test, elasticity formula and simulation analysis were also contrasted.4.By effective FEM model, Sensitivity analysis of mechanical parameters to deformation of surrounding rock was studied. Stability of depending tunnel in a fracture was studied, Reasonable tunnel starting scheme in partial press was studied, mechanical characteristic of long pipe shed was studied, Stability of slope with anti-slide piles under tunneling was studied.5.Strength displaying factor of tunnel support was defined. According to test result of pressure of surrounding rock, by development program based on load-structure model, Long-period security and strength displaying factor of tunnel support were studied for the depending engineering. It is found that, the tunnel applied by test pressure is safety. The minimum coefficient of safety for the tunnel applied by frozen-heave force meets the specification in tested cross-section in classified VI&V surrounding rock.更多还原