复杂长竖井长距离引水隧洞施工进度风险分析与仿真优化研究

发布时间：2018-08-26 19:24

【摘要】：复杂长竖井长距离引水隧洞工程对于地下空间的合理与有效利用意义重大。然而,长竖井长距离引水隧洞施工是一个极其复杂的过程,由于其独特的工程结构及复杂的施工环境,易引起上下平洞之间的气压差,且其通风断面小、距离长容易造成通风散烟困难;同时其施工过程存在的工序持续时间和逻辑关系变化结果导致风险概率升高;以及由于采用钻爆法和TBM法开挖造成施工方式多样复杂。这为长竖井长距离引水隧洞施工过程的研究分析带来了极大的挑战。传统的全过程仿真技术虽然可实现施工方案的优选和施工过程的描述,然而初始的仿真系统无法解决通风参数的科学取值、模型逻辑关系和活动时间的风险性分析等问题;同时,传统的仿真系统输出结果无法进行施工参数对工期影响的灵敏性分析。因此,本文就上述问题展开深入的研究分析,以期为复杂长竖井长距离引水隧洞施工进度风险分析与仿真优化研究提供理论依据与技术支撑。研究取得了以下主要成果:1、结合长竖井长距离引水隧洞复杂的施工特点,在通风数值模拟与进度风险分析的基础上,在原有仿真模型中既考虑通风参数的科学取值,又进行了模型逻辑关系和活动时间的不确定性分析,以优化传统隧洞仿真模型。长竖井长距离引水隧洞施工面临着施工战线长、施工强度高以及开挖工程量大等一系列问题,是一个极其复杂的过程。目前的长距离引水隧洞施工仿真模型中,通风参数多依靠工程类比与专家经验来选取,缺乏一定的科学性;且模型建立过程中没有考虑施工风险对施工进度的影响,降低了模型的实践意义。针对上述问题,本文在仿真模型中增加综合考虑多洞交叉布置和长竖井气压差特点的施工通风数值模拟模块和施工进度风险分析模块,以分析通风对施工进度的影响并确定科学合理的通风参数以及分析工序逻辑关系不确定性与活动时间不确定性对隧洞施工进度的影响。通过上述两个模块的加入来优化长竖井长距离引水隧洞施工仿真模型,提高仿真结果的准确度和可靠性。2、针对传统钻爆法施工通风散烟时间凭经验确定的不足,结合带有长竖井的复杂长距离引水隧洞施工通风特点,提出基于Euler-Euler两相流数值模拟的施工通风时间参数确定方法。传统的隧洞钻爆开挖施工通风研究中时间参数多是凭经验确定,而且对洞室内风流路径和污染物扩散过程难以预测。复杂长竖井长距离引水隧洞的施工工作面多,通风距离长,且长竖井的布置使通风散烟更加困难。现有引水隧洞的两相流模拟研究多是针对单一隧洞独头掘进的Euler-Euler两相流研究,对多洞交叉情况下施工通风的Euler-Lagrange模拟研究初有涉及,但都未直观得出在长竖井气压差和多洞交叉分布影响下的复杂长距离引水隧洞施工通风污染物浓度空间分布和随时间运移机制。因此,本文建立了综合考虑多洞交叉布置和长竖井气压差特点的复杂长竖井长距离引水隧洞施工通风euler-euler两相流紊流模型,模拟得出污染物随时间和空间变化的扩散运移,进而得出科学的通风时间参数,以期为仿真参数的优化和工程实际提供理论依据。3、针对目前进度风险分析研究中主要考虑活动时间不确定性而忽略逻辑关系不确定性的不足,提出了综合考虑逻辑关系不确定性和活动时间不确定性的复杂长竖井长距离引水隧洞施工进度风险分析方法。复杂长竖井长距离引水隧洞建设周期长、施工强度大、隧洞及支洞布置纵横交错,是一个复杂的系统工程。长竖井由于其独特的工程结构及复杂的施工环境,施工过程面临着钻挖工艺繁杂、地质条件多变等问题。其施工过程存在的诸多不确定因素不仅会对工序持续时间造成影响,还会引发风险事件,导致工序逻辑关系发生变化,进而影响长竖井长距离引水隧洞施工进度。目前的进度风险分析主要研究活动时间不确定性,未考虑施工中风险事件发生导致工序间逻辑关系变化对施工进度的影响。针对上述问题,充分考虑复杂长竖井长距离引水隧洞特有的施工工艺及多变的施工环境等特点,从逻辑关系不确定性和活动时间不确定性两个方面开展隧洞施工进度风险分析。与目前进度风险分析相比,提出的同时考虑逻辑关系不确定性和活动时间不确定性的风险分析方法可实现对施工风险更全面的分析,为复杂长竖井长距离引水隧洞施工进度管理提供科学的指导。4、针对施工工期受工序持续时间和施工参数影响的问题,采用极差分析法,对长竖井长距离引水隧洞施工工期进行多因素灵敏性分析。长竖井长距离引水隧洞施工过程同时采用钻爆法与tbm法两种洞室开挖方式,施工方式更为复杂,施工难度更大,施工过程中的不确定性与随机性更高,然而,以往的研究主要针对单一施工方式的工程问题展开,并且缺乏针对多因素对工期影响的分析研究,对实际施工的指导作用有限。针对上述问题,基于极差分析法对长竖井长距离引水隧洞的施工工期进行多因素灵敏性分析,在隧洞施工进度风险分析的基础上,判断可能影响工期的关键路线上的仿真工序持续时间和全部仿真参数对工期的影响程度。与目前的引水隧洞施工工期灵敏性分析研究相比,基于极差分析法的多因素灵敏性分析可以判断出所有可能的施工仿真影响因素对工期的影响程度,识别出对工期影响显著的关键施工工序和施工参数,为施工组织计划的制定和现场施工的管理提供了科学全面的依据。5、依托某复杂长竖井长距离引水隧洞施工工程,进行应用研究,验证了上述理论和方法的可行性。(1)以某水电站复杂长竖井长距离引水隧洞施工通风过程为实例,运用所建立的Euler-Euler气固两相流数学模型进行模拟研究。通过现场试验验证了数学模型的可靠性,实测值和模拟值之间体现良好一致性。为得到合理的网格划分方案,对计算网格进行了网格灵敏性分析。对数值计算结果进行分析,研究了风流组织结构和污染物的扩散运移规律,得出了通风散烟时间与钻爆开挖长度之间的关系,优化了仿真参数的选取。(2)结合工程背景,分别采用概率分支法和统计钟法分析地质风险和设备风险影响下的长竖井长距离引水隧洞施工逻辑关系不确定性;采用最乐观时间、最可能时间、最悲观时间和0.75分位数确定活动时间β分布函数,并采用舍选法进行抽样,以实现活动时间的不确定性分析。(3)在隧洞施工仿真中考虑通风参数的科学取值、模型逻辑关系和活动时间不确定性分析,进行长竖井长距离引水隧洞施工全过程仿真。不仅可以获得工期、关键线路、资源强度等仿真成果,还可通过多次仿真求得完工概率、完工风险、最关键线路和工序关键度等风险指标,为复杂长竖井长隧洞施工进度管理提供科学的指导。(4)依托长竖井长距离引水隧洞施工全过程动态仿真模型,在隧洞施工进度风险分析的基础上,分别对单项工程活动持续时间对总工期波动影响、施工参数对单项工程活动持续时间波动影响这两个阶段进行长竖井长距离引水隧洞施工工期多因素灵敏性分析;采用极差分析法分别对关键路线上的工序持续时间对工期的影响、施工参数对工序持续时间的影响进行统计分析;判断仿真模型中的全部仿真参数对工期的影响程度,识别出施工中需要重点控制的施工工序与施工参数,为施工进度计划的安排以及现场施工工期的控制提供理论依据。
[Abstract]:However, the construction of long-distance diversion tunnel with long shaft is a very complicated process. Because of its unique engineering structure and complex construction environment, it is easy to cause the air pressure difference between the upper and lower level tunnels, and its ventilation section is small and the distance is long. It is easy to cause the difficulty of ventilation and smoke dispersal; at the same time, the change of working procedure duration and logical relationship in the construction process results in the increase of risk probability; and the various and complex construction methods caused by the use of drilling and blasting and TBM excavation. This brings great challenges to the study and analysis of the construction process of long-distance diversion tunnel with long shaft. Although the whole process simulation technology can realize the optimization of construction scheme and the description of construction process, the initial simulation system can not solve the scientific value of ventilation parameters, the risk analysis of model logic relationship and activity time, etc. At the same time, the traditional simulation system output results can not carry out the influence of construction parameters on the construction period. Sensitivity analysis. Therefore, this paper carries out in-depth study and Analysis on the above problems in order to provide theoretical basis and technical support for risk analysis and simulation optimization of construction schedule of complex long-distance diversion tunnel with long shaft. On the basis of value simulation and schedule risk analysis, the original simulation model not only considers the scientific value of ventilation parameters, but also analyzes the uncertainties of logical relationship and activity time of the model in order to optimize the traditional tunnel simulation model. In the current simulation model of long-distance diversion tunnel construction, the ventilation parameters are mostly selected by engineering analogy and expert experience, and lack of certain scientificity; moreover, the influence of construction risk on construction schedule is not considered in the process of model establishment, which reduces the practical significance of the model. To solve the above problems, this paper adds a numerical simulation module of construction ventilation and a risk analysis module of construction schedule to the simulation model, which considers the characteristics of multi-tunnel cross-layout and long shaft air pressure difference comprehensively, in order to analyze the influence of ventilation on construction schedule and determine scientific and reasonable ventilation parameters, as well as to analyze the uncertainty of the logical relationship between the process and the activity time. The influence of uncertainty on tunnel construction schedule is studied. The simulation model of long-distance diversion tunnel with long shaft is optimized by adding the above two modules to improve the accuracy and reliability of simulation results. 2. Aiming at the shortage of ventilation and smoke dispersal time determined by experience in traditional drilling and blasting method, combined with complex long-distance diversion with long shaft. Based on Euler-Euler two-phase flow numerical simulation, a method for determining time parameters of construction ventilation in tunnel construction is proposed. The time parameters in traditional tunnel excavation ventilation research are mostly determined by experience, and it is difficult to predict indoor air flow path and pollutant diffusion process. The existing two-phase flow simulation research of diversion tunnel is mostly focused on the Euler-Euler two-phase flow research of single tunnel heading alone. The Euler-Lagrange simulation study of construction ventilation in the case of multi-tunnel crossing has been initially involved, but it is not intuitively concluded that the construction ventilation is long. The spatial distribution and time-dependent transport mechanism of ventilation pollutants in complex long-distance diversion tunnels under the influence of vertical pressure difference and multi-tunnel cross-distribution are presented in this paper. 3. In order to provide a theoretical basis for the optimization of simulation parameters and engineering practice, the shortcomings of considering the uncertainty of activity time while ignoring the uncertainty of logical relationship in the current schedule risk analysis are proposed. A risk analysis method for construction schedule of long-distance diversion tunnel with complex long shaft considering both uncertainty of logic relationship and uncertainty of operation time is presented.The construction period of long-distance diversion tunnel with complex long shaft is long,the construction intensity is large,and the arrangement of tunnel and its branches is crisscross. The construction process is confronted with the problems of complicated drilling and excavation technology and changeable geological conditions in the complex construction environment. Many uncertain factors in the construction process will not only affect the duration of the working procedure, but also cause risk events, resulting in the change of the logical relationship of the working procedure, thereby affecting the construction of long-distance diversion tunnel with long shaft. Schedule. Current schedule risk analysis mainly focuses on the uncertainty of activity time, and does not consider the influence of the change of logical relationship between processes caused by the occurrence of risk events on the construction schedule. Compared with the current progress risk analysis, the proposed risk analysis method, which considers both the uncertainty of logical relationship and the uncertainty of activity time, can realize a more comprehensive analysis of construction risk and is a complex long-distance diversion tunnel with long shaft. 4. Aiming at the problem that the construction period is affected by the duration of the working procedure and the construction parameters, the sensitivity analysis of the construction period of the long-distance diversion tunnel is carried out by using the range analysis method. Excavation method is more complicated, construction is more difficult, uncertainty and randomness are higher in the construction process. However, previous studies mainly focus on the engineering problems of a single construction method, and lack of analysis and Research on the impact of multiple factors on the construction period, which has limited guiding effect on the actual construction. Based on the risk analysis of tunnel construction schedule, the duration of simulation procedure and the influence degree of all simulation parameters on the construction period of the key route which may affect the construction period are judged. Compared with sensitivity analysis, sensitivity analysis based on range analysis method can judge the influence degree of all possible construction simulation influencing factors on the construction period, identify the key construction procedures and construction parameters which have significant impact on the construction period, and provide a scientific and comprehensive for the formulation of construction organization plan and site construction management. According to. 5, the feasibility of the above theory and method is verified by applying the construction project of a complex long-distance diversion tunnel with a long shaft. (1) Taking the construction ventilation process of a complex long-distance diversion tunnel with a long shaft as an example, the Euler-Euler gas-solid two-phase flow mathematical model is used to simulate and study. In order to get a reasonable mesh generation scheme, the grid sensitivity analysis was carried out. The numerical results were analyzed, and the air flow structure and pollutant diffusion and transport law were studied. The time of ventilation and smoke dispersion were obtained. The relationship between the length of drilling and blasting excavation and the selection of simulation parameters are optimized. (2) Combining with the engineering background, probabilistic bifurcation method and statistical bell method are used to analyze the uncertainty of long-distance diversion tunnel construction logic relationship under the influence of geological risk and equipment risk; the optimistic time, the most likely time, the pessimistic time and 0.75 points are used. (3) Considering the scientific value of ventilation parameters, the logical relationship of the model and the uncertainty analysis of the activity time, the simulation of the whole construction process of the long-distance diversion tunnel with a vertical shaft is carried out. The simulation results such as time limit, critical line, resource strength, etc. can also be obtained through many times of simulation, and the risk indexes such as completion probability, completion risk, most critical line and process criticality can be obtained, which can provide scientific guidance for the construction schedule management of complex long shaft long tunnel. (4) Based on the dynamic simulation model of the whole construction process of long shaft long distance diversion tunnel, in the On the basis of risk analysis of tunnel construction schedule, multi-factor sensitivity analysis of long-distance diversion tunnel construction period is carried out in the two stages of the influence of duration of single project activity on the fluctuation of total construction period and construction parameters on duration fluctuation of single project activity respectively, and the critical route is analyzed by range analysis method. The influence of process duration on construction period and the influence of construction parameters on process duration are analyzed statistically; the influence degree of all simulation parameters on construction period in simulation model is judged; the construction process and construction parameters that need to be controlled in construction are identified; the construction schedule and the construction period on site are arranged and controlled. Provide theoretical basis.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV511

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