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隔热涂层对高温隧洞支护结构温度应力的影响
Influence of Thermal Insulation Coating on Temperature Stress in Support Structures of High-Temperature Tunnels
为解决高地温引水隧洞支护结构在运行过程中因拉应力过大导致的开裂问题,以某高地温引水隧洞为例,采用三维有限元仿真技术,模拟了不同隔热涂层厚度条件下隧洞全生命周期的温度与应力变化,并评估了其对抗裂安全性的提升作用。研究发现,随着隔热涂层厚度的增加,二次衬砌内外温差显著减小,同时,在过水前施加隔热涂层能够有效降低运行期二次衬砌所受拉应力,且涂层厚度与拉应力降幅之间呈正相关关系,不满足抗裂安全标准的区域面积也相应减少。当隔热涂层厚度为2 mm时,二次衬砌各部位拉应力均保持在材料极限抗拉强度之下,且大部分部位能满足抗裂安全度≥1.6的要求。研究成果可为类似高地温隧洞支护结构温控防裂提供参考。
[Objective] This study focuses on the issue of cracking in the support structures of high-temperature water diversion tunnels during the operation period caused by excessive tensile stress. An active thermal control strategy involving the application of thermal insulation coatings with specific thicknesses before water flow in the tunnel is proposed and systematically quantified. This study evaluates the regulatory effect of this strategy on the temperature and stress fields throughout the life cycle of the tunnel (from construction to operation) and its role in improving crack resistance safety. [Methods] Based on a three-dimensional thermo-mechanical coupled finite element method, a typical high-temperature water diversion tunnel was used as the engineering background. The temperature evolution and stress response of the structure under different thermal insulation coating thicknesses were precisely simulated. [Results] The thermal insulation coating significantly improved the temperature gradient of the secondary lining. As the coating thickness increased, the temperature difference between the inner and outer sides notably decreased. The application of thermal insulation coating before water flow in the tunnel effectively suppressed the temperature difference between the inner and outer sides of the secondary lining and the resulting tensile stresses. The coating thickness was positively correlated with the reduction in tensile stress, leading to a corresponding decrease in the area of zones that did not meet crack resistance safety criteria. In particular, when the coating thickness was 2 mm, the peak tensile stresses at all key locations of the secondary lining were below the ultimate tensile strength of the material. Except for localized high-stress zones, the crack resistance safety factor in the majority of the zones remained stable above 1.6, significantly outperforming the no-coating or thin-coating schemes. [Conclusion] Pre-applying a thermal insulation coating of appropriate thickness (such as 2 mm) before water flow in the tunnel is a highly efficient and innovative thermal control and cracking prevention strategy. This source-intervention approach significantly reduces the tensile stresses induced by temperature loads, fundamentally enhancing the structural safety and durability of high-temperature tunnels during long-term operation. The research findings provide direct quantitative design guidance and key technical support for similar engineering projects.
高地温引水隧洞 / 有限元仿真 / 温度场 / 应力场 / 抗裂安全度
high-temperature water diversion tunnel / finite element simulation / temperature field / stress field / crack resistance safety degree
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为研究爆破荷载作用下隧道裂隙围岩的塌方规律,以连云港北固山隧道为工程背景,借助UEDC离散元数值模拟软件,模拟隧道钻爆法施工时裂隙围岩塌方运动全过程, 揭示塌方过程中位移、速度、加速度等的变化规律,并深入探究不同节理分布时隧道塌方运动和破坏形态演变过程,为类似隧道工程建设提供借鉴。结果表明:爆破荷载作用下隧道裂隙围岩位移先小幅上升后下降;不同倾角节理分布时隧道塌方运动主要是形变和滑移;45°节理与另一不同倾角的节理组合时,隧道塌方运动主要表现为形变、开裂和塌落。
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To study the collapse law of tunnel surrounded with fracture rock under blasting load, this paper simulates the collapse process of fracture surrounding rock while the tunnel suffers blasting excavation by virtue of discrete element method software UDEC relying on Beigu Mountain Tunnel engineering in Lianyungang. This research reveals the changing rule of factors including displacement, velocity and acceleration while the crack surrounding rock falling down. Furthermore, it explores collapse and failure pattern of fracture surrounding rock with different joints. In this way, this research can provide reference for similar tunnel construction. The results illustrate that: The fracture surrounding rock rises a little and then falls when it is exposed to explosion. The landslide motion is mainly divided into deformation and slip as the joint inclination varies. When the 45-inclination-angle joint combines with another different inclination-angle joint, the rock mass reflection can be concluded as deformation, cracking and falling.
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研究目的: 西南山区花岗岩隧道地处雅鲁藏布江缝合带地区,地质条件极其复杂,区域地质构造作用强烈,隧道建设中面临的高地应力及岩爆灾害风险异常显著。根据隧址区地质资料,结合附近工程区的地应力测试数据,通过COMSOL建立隧道数值计算模型,采用边界荷载调整法反演分析隧址区的初始地应力场,研究分析隧址区的地应力特征,并探讨花岗岩隧道沿线岩爆危险性等级。 研究结论: (1)花岗岩隧道轴线最大水平主应力S<sub>H</sub>为5.1~33.5 MPa,竖向主应力S<sub>v</sub>为4.2~55.1 MPa,隧道沿线80.48%的区域处于高到极高地应力状态;(2)当隧道埋深小于600 m时,花岗岩隧道主要以水平构造应力为主,应力场类型主要为S<sub>H</sub>>S<sub>v</sub>>S<sub>h</sub>,表现应力结构为走滑型;当隧道埋深超过600 m,大埋深的竖向主应力开始占据主导地位,应力场类型主要为S<sub>v</sub>>S<sub>H</sub>>S<sub>h</sub>,表现应力结构为正断型;(3)花岗岩隧道地层多为Ⅱ、Ⅲ级硬质脆性围岩,根据岩石弹性能指数和岩石脆性系数测试结果,中粒角闪黑云花岗岩具有中等岩爆倾向的储能和释能条件;(4)基于最大初始地应力值S<sub>max</sub>和岩石强度应力比R<sub>c</sub>/S<sub>max</sub>双指标评价法,花岗岩隧道全长13 047 m,其中强烈和极强岩爆风险段共9 000 m,占比68.98%;(5)本研究结论可为类似地质条件下的复杂山区深埋长大隧道勘察设计及岩爆灾害防治提供数据支撑。
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<b>Research purposes:</b> The granite tunnel in the southwest mountainous area is located in the Yarlung Zangbo River suture zone, the geological conditions are extremely complex and the regional tectonic action is strong, and the risk of high geo-stress and rockburst disaster in tunnel construction is extremely significant. According to the regional geological data, combined with the measured in-situ stress data of the nearby engineering area, the numerical calculation model of the tunnel was established by COMSOL, the initial in-situ stress field of the tunnel site area was analyzed by the boundary load adjustment method, the in-situ stress characteristics was studied, and the rock burst hazard level of the granite tunnel was discussed.<br/><b>Research conclusions:</b> (1)The maximum horizontal principal stress S<sub>H</sub> of the granite tunnel axis is 5.1~33.5 MPa, the vertical principal stress S<sub>v</sub> is 4.2~55.1 MPa, and 80.48% of the area along the tunnel is in the state of high to extremely high in-situ stress.(2)When the tunnel depth is less than 600 m, the granite tunnel is mainly dominated by horizontal tectonic stress, the stress field type is mainly S<sub>H</sub>>S<sub>v</sub>>S<sub>h</sub>, and the stress structure is strike-slip type.When the tunnel buried depth exceeds 600 m, the vertical principal stress of large buried depth begins to dominate, and the stress field type is mainly S<sub>v</sub>>S<sub>H</sub>>S<sub>h</sub>, indicating that the stress structure is a positive fault type.(3)The granite tunnel strata are mostly hard and brittle surrounding rocks of grade Ⅱ and Ⅲ. According to the test results of rock elastic energy index and brittleness coefficient, the medium grain amphibolite black cloud granite has the energy storage and energy release conditions of medium rockburst tendency.(4)Based on the evaluation method of the maximum initial stress value S<sub>max</sub> and the rock strength stress ratio R<sub>c</sub>/S<sub>max</sub>, the total length of the granite tunnel is 13 047 m, and the risk section of strong and extremely strong rockburst is 9 000 m, accounting for 68.98%.(5)The research conclusion of this paper can provide data support for the investigation and design of deep-lying long tunnel and rockburst disaster prevention in complex mountainous areas under similar geological conditions.
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结合岩爆的分类、机制、评价预警方法及防控原则,对深埋隧洞施工期岩爆主动和被动防控措施进行了梳理,重点分析其作用机理、适用范围与防控效果。对比了钻爆法和全断面隧道掘进机(TBM)法施工下岩爆的不同特征规律及防控重点,调研了典型水工隧洞的岩爆防控技术应用情况,包括锦屏二级水电站引水隧洞、引汉济渭工程秦岭隧洞、N-J水电站引水隧洞和滇中引水工程香炉山隧洞。结果表明:岩爆的主动防控措施包括钻孔应力释放、超前应力解除爆破、先导洞、高压喷水、钻孔注水、超前锚杆和预应力锚杆支护;被动防控措施包括喷锚支护、钢支撑、钢筋网(柔性钢丝网);钻爆法的岩爆防控重点是及时封闭支护,TBM法则需通过主动防控规避强烈-极强岩爆;当前大型水工隧洞的岩爆防治普遍采取主动+被动联合防控,主动措施以超前应力释放为核心,被动措施则采取“喷锚网+钢拱架”共同加固围岩,且注重使用快速柔性支护型式;岩爆的动态防控、量化精准防控以及发展更高效的超前应力释放技术和柔性吸能支护体系是值得进一步研究的方向。
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The classification, mechanism, evaluation, prediction methods and prevention principles of rockburst are briefly introduced first. On this basis, active and passive prevention and control techniques for rockburst during deep tunnel construction are summarized. In particular, the mechanism, application scope and prevention effects of such measures are highlighted. The differences of rockburst characteristics between drilling and blasting (D&B) method and tunnel boring machine (TBM) method are analyzed, and the applications of rockburst prevention techniques in typical projects are investigated. Such projects include the diversion tunnel of Jinping II hydropower station, the Qinling tunnel of Hanjiang-to-Weihe River Diversion Project, the diversion tunnel of Neelum-Jhelum (N-J) hydroelectric project in Pakistan and Xianglushan tunnel of the diversion project in Central Yunnan. 1) Active rockburst prevention techniques include borehole stress release, advanced stress relief blasting, pilot tunnels, high-pressure water injection, advanced anchor bolts and pre-stressed anchor bolts; passive prevention techniques include shotcrete-bolt support, steel support and reinforcement mesh (flexible steel wire mesh). 2) Timely closed support and active measures against strong-extremely-strong rockburst are the key points of preventing rockburst induced by D&B method and TBM method, respectively. 3) At present, active and passive measures are combined for the rockburst prevention of large hydraulic tunnels. For active prevention, advance stress release is the dominant measure, while for passive prevention, shotcrete-bolt-mesh combined with steel support is adopted together with the use of fast flexible support. 4) Dynamic prevention, precise quantitative prevention, and more efficient advanced stress release technology and flexible energy absorption support system are research directions in future.
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工程岩体分级是岩石力学及其工程应用研究的最基本内容之一,当前岩体分级体系中尚无考虑高地温及高温度梯度等复杂地质环境下的围岩分级方法。依托南疆某水电站高温洞段引水隧洞工程建设,基于现场地质描绘、现场钻孔测试及室内岩石力学试验成果,采用RMR、GSI、BQ和HC等不同分级体系对高温洞段开展岩体质量评价;最后根据实际围岩级别与定性和定量分级结果对比分析,提出了高地热下围岩类别影响因子及阈值指标,给出了高地热赋存环境状态对围岩分级的修正方法,在此基础上提出适用于高地温梯度环境下的隧洞围岩质量分级与评价方法。研究表明,考虑了温度修正后,各类围岩的岩体质量评价结果相对传统方法减小1/4~1/2级,与实际定级结果更为接近,提高了分级的准确率。研究结果对于存在高地温的隧洞围岩分级有参考价值。
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The classification of engineering rockmass is a most basic content in rock mechanics and rock engineering application research area. However, current applied rockmass classification system doesn’t cover the rockmass classification method for surrounding rockmass under special geological conditions, such as high ground temperature and high temperature gradient. On background of a hydropower station construction in south Xinjiang, a segment of diversion tunnel with high ground temperature is chosen for surrounding rockmass classification research. On the basis of field geological mapping, in-situ acoustic test and laboratory rock mechanics test results, the RMR, GSI, BQ and HC systems are applied respectively to the rockmass classification and rockmass quality evaluation for the research segment. According to actual surrounding rockmass grade as well as qualitative and quantitative grading results, the influence factors and threshold indexes of high ground temperature are proposed. The evaluation method of surrounding rock quality method of tunnel under complex geological conditions is obtained. Results show that the rockmass quality evaluation grade results with the proposed method are reduced by 1/4~1/2 grade, much closer to the actual grading results.
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郭平业, 卜墨华, 张鹏, 等. 高地温隧道灾变机制与灾害防控研究进展[J]. 岩石力学与工程学报, 2023, 42(7): 1561-1581.
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李准. 玉磨铁路高地温隧道降温技术及其经济研究[J]. 铁道工程学报, 2022, 39(6):95-99.
研究目的: 在铁路建设过程中,正确处理高地温段落施工及合理确定其投资是铁路建设者需要考虑的重要问题。本文以玉溪至磨憨铁路中七座高地温隧道施工为样本,对辅助坑道,单、双、三线段落施工进行技术经济研究,确定其工艺流程、施工参数和技术标准等问题,采用现场测定法和写实统计法,统计工料机消耗,测定分析降温措施补充定额及高温段落的工机降效费率,为完善同类工程的概预算编制体系提供参考。研究结论: (1)统计工料机消耗,可得到降温措施补充定额及高温段落的工机降效费率;(2)单线隧道高地温隧道Ⅳ级围岩施工条件下,温度等级为Ⅰ级、Ⅱ级、Ⅲ级时的降效系数分别为1.256、1.405和1.699;(3)建立隧道高温环境下施工的施工组织模型,最终可计算出常温段落与高温段落隧道特殊降温措施增加费率;(4)具体补充定额、降效费率及施组模型可为后续铁路项目提供借鉴和参考。
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<b>Research purposes:</b> Correct construction methods for high geothermal tunnel sector and reasonable investment are key considerations of designers in railway construction. This paper introduces a comprehensive technical and economic research on seven high geothermal tunnels in Yuxi to Mohan railway, including service gallery and single, double, triple line main tunnels. Labor cost, material and machine shift consumption are measured under certain construction parameters, technological process, technical requirements, using realistic statistical method and field measurement method. Supplementary quota of cooling measures and efficiency reduction rate of labor and machine are also analyzed afterwards, which will provide reference for perfecting the budgeting system of similar projects.<br/><b>Research conclusions:</b> (1) The consumption of labor cost, material and machine is counted, and the supplementary quota of cooling measures and the efficiency reduction rate of labor and machine in the section of high temperature are obtained. (2) Under the construction condition of grade Ⅳ surrounding rock of single-line tunnel with high ground temperature, the efficiency reduction coefficients of gradeⅠ, Ⅱ and Ⅲ are 1.256, 1.405 and 1.699. (3) The construction organization model of tunnel construction under high temperature environment is established, and the increase rate of special cooling measures for normal temperature section and high temperature section tunnel can be finally calculated. (4) The supplementary quota, efficiency reduction rate and construction organization model can provide reference for subsequent railway projects.
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谢高英. 高地温隧道施工期冰块辅助降温效果研究[J]. 地下空间与工程学报, 2023, 19(4):1329-1338.
为了解决高地温隧道施工环境的热害难题,研究冰块辅助手段降温效果并确定其设计参数,以成昆铁路保安营隧道工程为依托,采用现场实测数据验证的数值模型就不同冰块形状和布置方式对高地温隧道中不同截面位置温度场分布影响问题进行了深入分析。研究表明:与纯机械通风对比,加以冰块辅助后各截面气温显著降低且各截面温度差距显著减小;立墙式冰块双侧布置降温速度最快,立墙形状比立方体形状快约20%,双侧布置比单侧布置快约15%;冰块用量相同条件下,通风30 min后隧道气温与其形状和布置方式关联性不大,冰块起到的作用主要为冷却被围岩加热后的新鲜风并维持其温度,隧道气温主要由通风温度决定。
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In order to solve the problem of heat damage in high ground temperature tunnel construction environment, the cooling effect of ice cube assisted method is studied and its design parameters are determined. Based on the Chengkun Railway Baoangying tunnel project, the numerical model is verified by field measured data and was used to conduct an in-depth analysis of the influence of different ice shapes and arrangements on the temperature field distribution of different cross-sectional locations in high ground temperature tunnels. The results show that: compared with pure mechanical ventilation, the temperature of each section is significantly lower and the temperature difference between sections is significantly reduced with the aid of ice blocks. The cooling speed of wall-shaped ice blocks arranged in double-sided is the fastest, about 20% faster than the cube shape, and the double-sided arrangement is about 15% faster than the single-sided arrangement. When the amount of ice is the same, the correlation between the tunnel temperature and the shape and arrangement of ice blocks after 30 min of ventilation is not significant, and the role of ice blocks is mainly to cool the fresh air heated by the surrounding rock and maintain its temperature, the tunnel temperature is mainly determined by ventilation temperature.
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蒋爽, 蒋涛, 王树刚, 等. 隧道围岩温度分析解及隔热层对衬砌温度的影响分析:以大瑞铁路高黎贡山隧道为例[J]. 隧道建设(中英文), 2020, 40(2):195-201.
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李燕波. 高温热害水工隧洞支护结构受力分析数值模拟研究[J]. 长江科学院院报, 2018, 35(2):135-139.
为得到高温热害水工隧洞支护结构的受力机理,以新疆某引水隧洞为例,通过理论计算并使用ANSYS建立热-固耦合模型,对高温热害隧洞支护结构的受力特征进行了计算和分析。结果表明:在围岩与混凝土间设置隔热层能显著改善一期混凝土衬砌的受力情况,衬砌平均应力减小约46%,对二期混凝土无明显影响;隔热层会使支护结构的平均位移增大约14%;隔热层能显著提高一、二期混凝土的安全系数,其均值>1。对隧洞进行喷锚支护并对二期混凝土进行配筋后,隔热层+一期混凝土+二期钢筋混凝土组成的支护结构可以满足工程安全性的要求,可应用于实际工程中。
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In order to obtain the stress mechanism of hydraulic tunnel lining under high geothermal condition, we calculated and analyzed the mechanical characteristics of a diversion tunnel in Xinjiang through theoretical calculation and ANSYS within established hot-solid coupling model. Interrelated analyses conclude that heat insulation layer between surrounding rock and concrete could obviously improve the stress situation of the primary concrete lining by reducing the average stress by about 46%, but had no significant effect on the secondary concrete lining; also the average displacement of the lining structure increased about 14%; the thermal insulation layer could also significantly improve the safety factor of primary concrete lining and secondary concrete lining, with the mean value greater than 1. The supporting system together with heat insulation layer, primary concrete lining and secondary reinforced concrete could meet the safety requirements, and can be used in practical engineering.
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王凯生. 高地温引水隧洞复合支护结构适应性评价及优化设计[D]. 石河子: 石河子大学, 2020.
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朱伯芳. 大体积混凝土温度应力与温度控制[M]. 北京: 中国电力出版社, 1999.
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沈思朝, 颉志强, 王首豪. 基于数值仿真的水闸温控措施敏感性分析[J]. 长江科学院院报, 2022, 39(1): 146-154.
水闸属于薄壁大体积混凝土结构,实践表明,若不采取温控措施,尤其是低温季节施工的混凝土水闸结构在浇筑初期极易出现表面裂缝,后期易扩展为贯穿性裂缝。弄清各温控措施对水闸温度场、应力场及开裂风险的影响,是制定水闸温控指标和防裂措施的前提。以某在建的低温季节浇筑水闸工程为研究对象,利用三维有限元法,计算分析了在低温季节浇筑施工时水闸结构的温度场、应力场特性,重点进行了开裂风险的敏感性分析。结果表明,单一温控措施的防裂效果有限,控温浇筑、表面保温、冷却通水必须相互协调,能有效控制水闸温度应力并避免裂缝产生。
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Sluice is a large-volume concrete structure with thin walls. Practice have shown that concrete sluice structure constructed in low-temperature season is subjected to surface cracks in the early stage of pouring if no temperature control measure is taken, and such surface cracks would penetrate through in later stage. To clarify the influence of temperature control measures on the temperature field, stress field and cracking risk of the sluice is the prerequisite of determining temperature control indices and formulating anti-cracking measures. With a sluice project under construction in low-temperature season as a case study, we examined the spatial and temporal characteristics of temperature field and stress field by simulating the construction process using 3D finite element method. On this basis, we analyzed the sensitivities of stress to pouring temperature, surface temperature preservation, and water cooling. Results manifested that single measure has limited effect. Multiple measures including temperature-control pouring, surface temperature preservation, and water cooling must be coordinated to effectively control the temperature stress of the sluice and avoid cracks.
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