寒区隧道水、热、力三场耦合分析与变形可靠度研究

发布时间：2018-12-26 15:01

【摘要】：随着近年来西部大开发战略的不断推进,西部高寒地区公路和铁路工程建设规模日渐扩大。在寒区公路和铁路工程建设过程中,修建了大量的隧道工程,然而在工程运营过程中,普遍出现了不同程度的冻害问题。本文针对寒区隧道的冻害问题,分析了冻害产生的机理,研究了寒区隧道围岩在冻融变化下的物理力学特性,推导了岩体的水、热、力三场耦合控制方程,并以巴哈达坂公路隧道为背景,建立了水、热、力三场耦合数学模型,对隧道建成后50年内的温度场、应力场及变形场进行模拟,计算分析了该隧道工程的变形可靠度和失效概率。主要内容包括:(1)归纳分析寒区隧道的冻害现象,主要表现为:衬砌渗漏水、挂冰,地道翻浆冒泥、冻胀结冰,衬砌破裂,洞门墙开裂,排水系统冻结堵塞,洞口处岩体和积雪热融滑塌等。(2)分析了隧道衬砌结构的冻害机理。寒区隧道冻害产生的主要原因是隧道岩体内部水分在温度降低到水的冰点以下时,水分冻结成冰产生体积膨胀对岩体和隧道衬砌产生冻胀力。(3)总结分析了温度场、渗流场、应力场耦合的基本理论,并建立了温度场、渗流场、应力场耦合控制方程。(4)以巴哈达坂隧道为背景,建立了温度场、渗流场、应力场耦合的数学模型,模拟分析了隧道建成后50年内的温度场、应力场及变形场的变化规律。结果表明:(1)温度场方面:隧道建成后第50年7月份,未铺设保温层隧道二次衬砌外侧的温度为5.26℃,铺设保温层隧道二次衬砌外侧的温度为1.64℃。未铺设保温层隧道围岩的融化深度为2.0m,铺设保温层隧道融化深度为1.1m,由此可知,铺设5cm厚的保温层对该隧道降温效果明显。(2)应力场方面:巴哈达坂隧道施工结束时,仰拱底部最大拉应力为0.32MPa,拱顶最大压应力为4.12MPa;隧道建成后第50年1月份,仰拱底部最大拉应力为1.36MPa,拱顶最大压应力为5.67MPa,由此可知,隧道建成后第50年,隧道仰拱底部衬砌的最大拉应力对隧道稳定性有较大影响。(3)变形场方面:巴哈达坂隧道施工结束时,隧道拱顶竖直向下的位移为2.07mm,仰拱竖直向上的位移为5.39mm;隧道建成后第50年1月份,拱顶竖直向下的位移为6.30mm,仰拱竖直向上的位移为9.32mm;隧道施工结束时,隧道侧墙的水平位移为2.98mm,隧道建成第50年1月份隧道侧墙的水平位移为6.59mm。(5)在巴哈达坂隧道温度场、应力场及变形场分析的基础上,采用响应面法和验算点法,并编写相应的计算程序,计算分析了隧道建成后50年内的可靠度指标和失效概率。计算结果表明,在容许变形量为8mm的情况下,巴哈达坂隧道施工结束时,隧道的可靠度指标为4.5052,隧道的失效概率为0.0016%;隧道的可靠度指标随时间的推移不断降低,隧道的失效概率不断增加,且增长速率逐渐增大,巴哈达坂隧道建成后第50年的变形可靠度指标为1.9736,相应的失效概率为5.6900%。
[Abstract]:With the development of the western region in recent years, the construction scale of highway and railway in the western alpine region is expanding day by day. In the process of highway and railway construction in cold region, a large number of tunnel projects have been built. In this paper, the mechanism of freezing damage is analyzed, and the physical and mechanical properties of surrounding rock in freezing and thawing are studied. The coupling control equations of water, heat and force of rock mass are deduced. Taking the Bahadaban Highway Tunnel as the background, the coupled mathematical model of water, heat and force is established to simulate the temperature field, stress field and deformation field within 50 years after the tunnel is completed. The deformation reliability and failure probability of the tunnel are calculated and analyzed. The main contents are as follows: (1) the freezing damage phenomenon of the tunnel in cold region is summarized and analyzed, which are mainly manifested as follows: lining leakage, ice hanging, tunnel mudding, frost heaving and icing, lining cracking, portal wall cracking, drainage system freezing and blocking, The mechanism of freezing damage of tunnel lining is analyzed. The main cause of tunnel frost injury in cold region is that when the water content in tunnel rock mass decreases below the freezing point of water, the volume expansion of water frozen into ice produces frost heaving force on rock mass and tunnel lining. (3) the temperature field is summarized and analyzed. The coupling control equations of temperature field, seepage field and stress field are established. (4) the mathematical model of temperature field, seepage field and stress field coupling is established based on the Bahadaban Tunnel. The variation of temperature field, stress field and deformation field within 50 years after tunnel completion is simulated and analyzed. The results show that: (1) the temperature field of the tunnel is 5.26 鈩，

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