甫当隧道温度应力场数值模拟分析

发布时间：2018-06-06 13:41

  本文选题：铁路隧道 + 高地热　； 参考：《兰州交通大学》2015年硕士论文

【摘要】：近几年来国家大力发展铁路市场,来带动国家经济的发展。国内高速铁路里程的日益增长,使得设计师们越来越多的使用桥梁与隧道来征服高山、跨越峡谷。隧道,作为线路中的一种常见的建筑结构形式,近几年来更是被广泛的应用,而且隧道的长度也在不断的增加。长大隧道的出现及长度的不断增长,在给线路选线工作提供便利的同时,以前不太明显的隧道病害,逐渐成为影响隧道施工及运营的重要因素。高地热问题就是近年来逐渐开始显现的一种隧道病害—地温场对隧道结构的影响程度也明显的提高。本文以高海拔、高地温的拉日线甫当隧道为依托,根据传热学所学的相关理论知识,运用ANSYS对现场实际情况进行数值模拟,分析了在施加了温度荷载的前后,二次衬砌结构的受力情况及安全系数,决定使用隔热材料来阻碍地层中热量流向隧道二次衬砌结构。结合现场实际情况,经过综合比选,确定了隔热层的材料种类和施做厚度。然后分两阶段—施工阶段及运营阶段对隧道进行通风降温,并计算运营期间二次衬砌内的应力及安全系数,确保隧道在施工过程中及使用年限内都有足够的可靠性。(1)运用ANSYS软件,分别计算分析甫当隧道二次衬砌结构仅在温度场和在温度应力场耦合作用下,应力分布特征及安全系数情况。结果显示,温度对结构内力影响较大,结构的安全系数降低。(2)分别模拟结构在施做隔热层前后,隧道二次衬砌内部结点温度情况。计算结果表明在施做隔热层后,二次衬砌结构的温度提升速率更为平缓,且在计算年限之内,隧道二次衬砌温度明显降低。(3)模拟分析不同材质及不同厚度的隔热层,结合实际情况,以经济合理为原则,选择最优隔热层施做方案—在二次衬砌及复合防水层之间,施做10cm厚复合型硅酸盐隔热层,来阻碍地层中热量流向隧道二次衬砌结构。(4)考虑隧道贯通以前,隧道内部空气与隧道外空气对流不明显,为保证施工人员的安全,施工机械设备的正常运作,决定使用通风机对隧道进行通风降温处理。模拟计算结果显示,当空气温度15℃、风管内风速大于15米/秒时,距离掌子面110米的范围内,隧道内部气温下降到30℃以内。(5)运营过程中,假设隧道内空气充分与洞外空气对流,计算结果显示,隧道二次衬砌结构在隧道内气温及隔热层的作用下,较不采取任何降温措施情况下,结构内部应力有所降低,整体安全性提高,运营通风满足要求。
[Abstract]:In recent years, the country has vigorously developed the railway market to drive the development of the national economy. With the increasing mileage of domestic high-speed railway, designers use bridges and tunnels to conquer mountains and cross canyons. Tunnel, as a common architectural structure, has been widely used in recent years, and the length of tunnel is increasing. With the appearance of long tunnel and the increasing length of long tunnel, it is convenient for the route selection work, but the tunnel disease, which was not obvious in the past, has gradually become an important factor affecting the tunnel construction and operation. The high geothermal problem is a kind of tunnel disease which gradually appears in recent years-the influence degree of the ground temperature field on the tunnel structure is also obviously improved. In this paper, based on the high altitude and high ground temperature pullout tunnel, according to the relevant theoretical knowledge of heat transfer, using ANSYS to carry out the numerical simulation of the actual situation in the field, the analysis is made before and after the temperature load is applied. Because of the stress and safety factor of the secondary lining structure, it is decided to use the heat insulation material to block the heat flow to the tunnel secondary lining structure. According to the actual situation in the field, the material types and the thickness of the heat insulation layer are determined by comprehensive comparison and selection. Then the tunnel is ventilated and cooled in two stages-construction phase and operation stage, and the stress and safety factor in the secondary lining during operation are calculated. To ensure that the tunnel has sufficient reliability during construction and service life. (1) using ANSYS software to calculate and analyze the secondary lining structure of the tunnel only under the coupling of temperature field and temperature stress field. Stress distribution and safety factor. The results show that the temperature has a great influence on the internal force of the structure, and the safety factor of the structure is reduced. 2) respectively, the temperature of the inner node of the tunnel secondary lining is simulated before and after the construction of the thermal insulation layer. The calculation results show that the temperature rise rate of the secondary lining structure is more gentle after the application of the heat insulation layer, and the temperature of the secondary lining of the tunnel decreases obviously within the calculated years. (3) the heat insulation layer of different materials and thickness is simulated and analyzed. In combination with the actual situation and taking the principle of economy and rationality as the principle, the best heat insulation layer is chosen-between the secondary lining and the composite waterproof layer, the 10cm thick composite silicate insulation layer is applied. To block the flow of heat in the formation to the secondary lining structure of the tunnel. (4) considering that before the tunnel is through, the convection between the air inside the tunnel and the air outside the tunnel is not obvious. In order to ensure the safety of the construction personnel, the normal operation of the construction machinery and equipment is ensured. It was decided to use ventilator for ventilation and cooling of tunnel. The simulation results show that, when the air temperature is 15 鈩，

本文编号：1986747