随机变量相关性对隧道二衬作用效应的研究

地下工程中岩土层自身的随机性、模糊性及不确定性因素使得隧道工程面临着较大风险。随着隧道工程的蓬勃发展,如何提高隧道工程衬砌结构的安全度、降低工程结构风险措施的研究显得尤为重要。然而,直至目前仍然没有系统、科学的方法来降低隧道工程风险。本文以可靠度理论为基础,同时基于ANSYS软件中的PDS技术,对隧道工程中二衬结构的某些参数的相关性入手,探讨随机输入变量的相关系数对二衬结构的作用效应的影响。研究成果表明:忽略随机变量之间的相关性将对计算结果造成很大误差;二衬作用效应与计算参数的相关系数之间存在一定的线性关系;隧道设计中应当考虑计算参数间的相关性才能使工程设计更贴近真实情况。     

城市综合管廊线性定位优化

随着城市的飞速发展,以传统直埋方式敷设的地下管线已经不能很好地满足现代化城市的发展需求,综合管廊的建设成为城市发展的必然趋势。为了提高综合管廊的利用效率,节省建设和运营成本,该研究在假设综合管廊是由多条垂直线和水平线组成的连续多段线基础上,以规划区内各需求点至水平线的距离加权之和最小为目标,构建了综合管廊中心线定位优化模型,得出了综合管廊中心线的平面定位。通过实例分析,验证了模型及求解程序的可行性。为综合管廊线路定位的定量研究提供了基础理论依据,并为综合管廊的合理规划提供了新思路。     

混沌理论在建筑设计中的应用

首先明确了混沌理论的含义,然后分析其理论来源及历史,之后从混沌理论内在随机性和初值的敏感性等的本质特征出发,简述在建筑与城市中的体现应用,最后简要指出其在建筑设计方面的意义。     

Optimal probability‐based partial mass isolation of elevated coal scuttle in thermal power plant building

Partial mass isolation (PMI) system is a practical strategy to mitigate seismic response of the main structure. Many studies provide various formulas to estimate an optimum design solution for the structure under simplified excitation models. But the efficiency of these optimization methods under actual ground motion records requires investigation. This paper proposes a new optimization design framework, which considers the randomness of ground motions. To describe the vibration depression effects of the PMI under various records, several theoretical distributions were assumed and tested. A Weibull distribution was selected because of its best performance in the chi‐squared tests among the several theoretical distributions. A sensitivity study on the number of records was performed to ensure the accuracy of estimated parameters with a relatively small sample size. This framework was adopted in the design of a PMI system for a large‐scale thermal power plant building through both single‐objective and multiobjective optimization procedures. Optimal design results from the single‐objective optimization procedure were compared with those from traditional formulas. Additionally, with the relative displacement limitation, the Pareto optimum set was obtained from the multiobjective optimization procedure. The final design was compared with the single‐objective optimization result.     

Management of road tunnels: Construction,maintenance and lighting costs

This paper presents a life cycle cost analysis, which compares construction, maintenance, and lighting costs needed to manage a highway tunnel. As regards the decision making process, it often considers only construction costs. Instead even maintenance and lighting, especially related to road tunnels, cause important cash flows. Therefore, both construction and managing costs have to be planned, in order to assess the cheapest solution. The lighting system of a road tunnel must guarantee the visual guidance for users moving at design speed and without hazardous actions.In this case study, the authors designed the pavement according to Italian standards and the lighting system according to Italian and European technical rules (UNI and UNI EN standards). They used LED technologies to maximize energy saving and road safety. The examined case study shows the importance of the surface pavement material, since it may contribute to the inter-reflected light and reduce electric energy consumption.     

牛家营二号隧道风积砂段施工技术

以牛家营二号隧道风积砂段隧道施工为例,着重对岩石隧道与风积砂隧道过渡段、风积砂隧道洞口段等施工技术进行了总结,通过该方案的实施,解决了风积砂隧道易塌方、出洞难等问题,简化了施工程序,节约了施工成本。     

Optimal cost design with sensitivity analysis using decomposition techniques. Application to composite breakwaters

Minimizing the expected total cost of a structure, including maintenance and construction is a difficult problem because of the presence in the objective function of the yearly failure rates, which have to be calculated by an optimization problem per each failure mode. In this paper, a new method for the design of structures that minimizes the total expected costs of the structure during its lifetime based on Benders’ decomposition is presented. In addition, some tools for sensitivity analysis are introduced, which make it possible to determine how the cost and yearly failure rates of the optimal solution are affected by small changes in the input data values. The proposed method is illustrated by its application to the design of a composite breakwater under breaking and non-breaking wave conditions.     

城市隧道施工穿越建(构)筑物风险管理体系

城市隧道不可避免临近既有建(构)筑物施工,使其结构安全面临较大风险。实施系统化、科学化和规范化的环境安全风险管理,确保建(构)筑物的安全是当前需要重点研究的问题。基于城市地下工程基本力学问题与风险管理目标的分析,结合工程实践,从系统的角度出发,提出了城市隧道施工穿越建(构)筑物安全风险管理的一般程序,具体阐述了其中所包含的建(构)筑物的现状评估和安全性评价、隧道施工方案优化、施工过程控制、过程监测及工后评估和恢复等五个方面的主要工作内容,强调从技术可操作性层面上对建(构)筑物安全性进行系统性控制,由此即构建了隧道施工穿越建(构)筑物安全风险管理体系。该体系已用于指导工程实际,取得了良好效果,也期待在基础理论研究、定量化研究及操作细化等问题上进一步深化和完善。     

Determining the principles of tunnel support based on the engineering geological behaviour types: example of a tunnel in tectonically disturbed heterogeneous rock in Serbia

A methodology for designing a tunnel support system according to the actual ground conditions and the critical behaviour types is analysed in this paper. The methodology is justified with the principles of the New Austrian Tunnelling Method that incorporates the top heading and bench method. The role of the geological material and its implication in tunnel design, reinforced with advances in site investigation methods, cannot be based solely on the development of the geotechnical classification systems and the consequent quantification of the rock masses. Support requirements for rock masses with equal classification ratings can be different. The procedure presented in this study cannot bypass the geological and/or in situ characteristics dictating or influencing the tunnel behaviour compared with a standardised classification that could miss the specifics and particularities of and around a tunnel section. The step-by-step procedure is applied in a tunnel excavated in tectonically disturbed heterogeneous flysch sediments in Serbia. The complex structure of these materials, resulting from their depositional and tectonic history that includes severe faulting and folding, presents a challenge to geologists and engineers. The possible ground types are evaluated, and then, combined with the factors of the tunnel geometry, the primary stress condition, and the water conditions, several behaviour types are considered. These classified behaviour types, followed by the suitable mechanical properties that are required for effective tunnel engineering design, are the basis for the numerical design of the appropriate primary support measures to achieve stable tunnel conditions. The twin-tube, two-lane highway tunnel was successfully constructed without significant problems.

     

公路隧道监控量测对塌方的预测作用之探讨

在隧道施工过程中,由于受工程地质、水文地质条件、自然灾害及人为因素等影响,易发塌方等地质灾害现象。在隧道工程中,监控量测作业的落实与数据反馈灵活的运用,除了可预防隧道灾害发生降低损失外,减少人员的伤亡,亦可以随时检验支护选取最经济最有效率的作业模式,大大的降低施工成本,真正保证隧道的施工安全。     

隧道施工控制技术在穿越既有高速公路工程中的应用研究

隧道工程的多元化发展促进了隧道施工技术的更新。在解决我国新建成隧道近距离穿越既有高速公路的问题时,怎样保证既有高速公路安全正常的运行,又能保证隧道的施工和质量安全,就需要我国的隧道施工技术上达到一定的高度,以保证施工的有效完成。     

广州城市隧道结构设计与景观优化探讨

结合广州市的一些城市车行隧道,阐述隧道景观设计的内容和方法,介绍如何在隧道景观设计中结合园林美学等知识,使隧道设计不仅满足其使用功能,而且更安全、舒适、美观以及更具艺术文化风格。     

Anwendung der Random‐Set‐Methode (RSM) für Standsicherheitsuntersuchungen im Tunnelbau

Application of the Random Set Method (RSM) for stability analyses in tunnel construction. This paper discusses the application of the Random Set Method (RSM) in tunnel construction. It shows the benefits, by means of an example, of using RSM for stability analyses. The results of the calculation using state‐of‐the‐art deterministic methods are compared with the results of RSM, which cover the entire range of parameters of a homogeneous section of a tunnel. For this investigation it is postulated that the stability of a tunnel is ensured when the actual deformations correspond with the calculated deformations. If the stability analysis is made using a deterministic approach, a significant degree of interpretation is required for the evaluation and comparison of measurement and calculation results. This is not the case when using RSM because the full range of possible parameters enters the analysis as compared to selected parameter combinations.     

地下水渗流作用下的盾构隧道开挖面安全系数上限分析

利用数值模拟技术对地下水渗流情况下盾构隧道开挖面的渗流场进行模拟,获得了隧道开挖面周边各节点的孔隙水压力。基于极限分析上限定理,利用各节点孔隙水压力计算出隧道开挖面上限破坏机制中的孔隙水压力功率,并将其视为一个外力功率代入虚功率方程中,构建出考虑渗流影响的开挖面安全系数目标函数。通过非线性序列二次规划法对该目标函数进行优化计算,得到开挖面安全系数上限解。利用强度折减法验证了该方法的有效性,并将其用于考虑地下水渗流作用的盾构隧道工程实例分析。研究表明:在考虑地下水渗流的情况下,开挖面安全系数随土体黏聚力、摩擦角、开挖面支护力的增大而增大,随地下水位的升高而减小;开挖面的破坏范围随摩擦角的增大而显著减小,但地下水位线的位置对开挖面的破坏范围影响较小。     

基于约束多目标优化算法的盾构隧道设计方法

当前盾构隧道的设计仍主要依托于经验确定设计参数,然后对其安全性进行校核,难以定量的考虑成本和控制指标(收敛变形等)的关系。以衬砌厚度、截面配筋率、横向接头螺栓直径为设计参数,以成本及结构的水平收敛变形为优化目标,结合多目标优化的算法,进行了盾构隧道的横断面设计。采用非支配原理,通过引入约束违反函数,实现了基于NSGA-Ⅱ算法的复杂约束条件处理。最后通过具体算例,完成了满足截面安全性要求的限制条件下,完整Pareto前沿面的获取工作,并与无约束优化结果进行了分析对比,说明了迭代过程的收敛性,阐述了所得Pareto前沿面的价值意义,得到了不同设计条件下的最优解。     

边坡爆破开挖对邻近已有洞室影响研究

边坡爆破施工振动对邻近已有洞室的影响及其控制是工程中的关键技术问题。新建边坡在与已有洞室间距比较小的情况下进行爆破开挖,爆破开挖产生的爆破波会危及已有洞室围岩和衬砌结构的安全与稳定性。结合锦屏一级水电站左岸坝肩边坡施工爆破对洞室影响的分析课题,应用动力有限元数值模拟,研究不同的边坡与已有洞室间距、岩体阻尼比、最大单响药量情况下边坡爆破振动对洞室围岩和衬砌结构的影响问题。根据洞壁质点振动速度允许值与洞室衬砌在边坡爆破振动波作用下的动拉应力值,考虑不同阻尼比,得出不同围岩级别下,不同边坡与洞室间距的最大单响药量控制：III类岩体边坡,坡面距已有洞室20,50 m时,边坡开挖爆破最大单响药量分别控制在100和300 kg以内;IV类岩体边坡,坡面距已有洞室20,50 m时,边坡开挖爆破最大单响药量分别控制在150和450 kg以内,研究结果为实际工程的施工和设计提供参考和依据。     

基于截面极限承载力曲线的衬砌厚度减薄研究

复合式衬砌结构的优化设计是隧道工程技术的重要研究课题之一。衬砌厚度过大、配筋过密,不仅造成经济浪费,还可能导致衬砌容易开裂。依托蒙华铁路隧道工程,通过现场试验和理论分析的方法,研究衬砌厚度减薄的可行性。首先,基于衬砌截面极限承载力曲线的概念,提出以抗弯安全系数评价衬砌安全性的方法。其次,根据现场试验得到的衬砌截面内力监测值,揭示了衬砌厚度减薄前、后,截面内力的变化特征,得到减薄衬砌厚度,衬砌截面的抗弯安全系数增大,抗弯安全性有所提高。最后,通过有限元数值计算,验证了现场监测得到的主要结果,即初期支护加强、衬砌减薄的复合式衬砌结构优化设计是可行的。研究结果表明,在隧道衬砌设计时,厚度设计过大会使其截面刚度过大,抗弯安全系数反而会减小,衬砌容易发生开裂破坏,适当减薄衬砌厚度,有利于保证其抗弯安全性。研究成果对复合式衬砌结构的设计具有一定的参考意义。     

跨越地铁隧道的结构分析与设计

广州市珠江新城核心区市政交通项目的主体结构从地铁5号线隧道上方跨越而过。结构设计中针对地铁保护的要求以及工程结构布置、岩土地质状况、各部位与地铁隧道的空间关系等具体条件,通过各类计算分析进行了多种结构方案对比,并将最终方案落实到结构设计中,同时提出了具体措施与要求。结合该工程上述方案对比及设计措施,为跨越地铁隧道的同类结构提供了分析与设计方面的经验与参考做法。     

衬砌背后双空洞影响下隧道结构的安全状态分析

衬砌背后多空洞的存在使隧道结构受力状态更加复杂,极易引起结构开裂并直接影响到隧道结构的安全性。针对Ⅳ级围岩两车道公路隧道,采用数值模拟和模型试验分别研究拱顶或拱肩背后存在双空洞条件下隧道结构的安全状态。数值模拟结果表明:衬砌背后双空洞的存在,显著改变了隧道结构内力分布,恶化了结构受力状态;空洞尺寸增大会导致隧道结构轴力整体降低,并使空洞范围内及两空洞之间的隧道结构弯矩明显增大;两空洞间隧道结构各截面安全系数较无空洞时显著降低,并表现出随空洞尺寸增加而逐渐降低的趋势,该区域也是隧道结构安全性评价重点部位;拱肩衬砌背后存在双空洞时,其对结构截面安全系数的影响较拱顶和拱肩分别存在空洞的情况更大。模型试验得到的空洞对衬砌结构安全系数影响规律与数值模拟结果基本一致,并获得了双空洞作用下衬砌结构的破坏演化规律。研究成果可为隧道衬砌背后空洞的致灾机制和灾变控制研究提供参考和借鉴。