长距离复杂洞室联动通风与污染物扩散的数值模拟研究

发布时间：2018-07-06 07:30

本文选题：地下洞室 + 施工通风　；参考：《清华大学》2015年博士论文

【摘要】：施工通风问题已经成为我国大型地下洞室工程施工最关键的一项制约因素,直接涉及到人员健康、施工效率、设备布置以及节能减排诸多方面。本文以我国某国家石油储备基地地下水封洞库工程为背景,采用现场测验、理论分析和计算流体力学(CFD)相结合的方法,对长距离复杂洞室群联动通风所涉及到的理论问题与实际问题进行了研究,取得了以下主要成果:现场测量的地下洞室内平均温度沿程分布稳定,为三维风流数学模型假定等温通风提供了依据。采用RNG k-ε湍流模型模拟三维附壁射流,计算的流场分布和边界层厚度均与实测值吻合良好,验证了湍流模型的正确性。采用组分输运模型模拟隧洞通风有害气体扩散,计算的有害气体浓度随时间变化规曲线与实测值基本吻合,为组分输运模型的正确性提供了佐证。提出当隧洞内工作面附近回流平均速度达到地下洞室施工通风规范要求的最小风速时的断面为临界断面,其与风筒出口之间的距离为最大风流有效作用长度。建立了隧洞压入式通风数值模型,根据模拟结果分析了影响射流和回流平均速度沿程分布无量纲曲线的因素,得到了射流和回流平均速度半经验公式。以最小风速为求解条件,由回流平均速度半经验公式构建了最大风流有效作用长度公式。将该公式应用于隧洞施工通风,计算结果与现场测量的风流有效作用长度最为接近,验证了该公式的正确性和实用性。对隧洞抽出式通风进行了数值模拟研究,提出了以风筒至边壁最大距离为依据的吸风有效作用长度计算公式。该公式的计算结果与美国矿山局给出的公式最为接近,并且考虑了隧道断面形状和风筒位置变化的影响。对采用不同型式射流口的隧洞进行了有害气体扩散数值模拟。渐变收缩型射流口增大了射流的紊动强度,渐变扩张型射流口增大了射流的扫掠面积。后者能使风筒出口与洞口之间的断面速度更快地趋于均匀,从而缩短隧洞施工所需的通风时间,加快施工进度。建立了地下石油水封洞库通风的复杂三维数值模型,针对实际施工中所需要解决的问题进行了模拟计算。获得了多断面施工、多点联动通风的风流方向、路径,找到了风流组织过程中存在的风流较弱的洞室通道,并分析了有害气体在地下洞室群中的动态变化过程及规律。为提高通风效率、消除有害气体滞留提出了优化方案,取得了良好的通风效果,为现场施工提供了重要的理论支撑。
[Abstract]:The problem of construction ventilation has become one of the most critical factors in the construction of large underground caverns in China, which directly involves the health of personnel, construction efficiency, equipment layout and energy saving and emission reduction. Based on the underground water sealing engineering of a national petroleum reserve base in China, this paper adopts the method of field test, theoretical analysis and computational fluid dynamics (CFD). In this paper, the theoretical and practical problems related to the combined ventilation of long distance and complex caverns are studied. The main results are as follows: the average temperature distribution in underground caverns measured in situ is stable, It provides a basis for the assumption of isothermal ventilation in three dimensional wind flow mathematical model. The RNG k- 蔚 turbulence model is used to simulate the three-dimensional wall-bound jet. The calculated flow field distribution and boundary layer thickness are in good agreement with the measured data, which verifies the correctness of the turbulent model. The component transport model is used to simulate the diffusion of harmful gas in tunnel ventilation. The calculated variation curve of harmful gas concentration with time is in good agreement with the measured value, which provides evidence for the correctness of the component transport model. It is proposed that the cross section of the tunnel is critical when the average velocity of reflux near the working face reaches the minimum wind speed required by the ventilation code for underground cavern construction, and the distance between the section and the outlet of the tube is the maximum effective length of air flow. The numerical model of tunnel pressure-in ventilation is established. Based on the simulation results, the factors influencing the distribution of the average velocity of jet and reflux along the path are analyzed, and the semi-empirical formula of the average velocity of jet and reflux is obtained. With the minimum wind speed as the solution condition, the maximum effective air flow effective length formula is constructed from the semi-empirical formula of average reflux velocity. When the formula is applied to ventilation in tunnel construction, the calculated results are most close to the effective length of air flow measured in the field, which verifies the correctness and practicability of the formula. In this paper, the numerical simulation of tunnel ventilation is carried out, and a formula for calculating the effective action length of suction wind based on the maximum distance from the tube to the side wall is put forward. The calculation results of the formula are most close to those given by the United States Mine Administration, and the influence of tunnel cross-section shape and tuyere position change is taken into account. Numerical simulation of harmful gas diffusion in tunnels with different jet orifices was carried out. The turbulent intensity of the jet is increased with the gradual shrinkage jet opening, and the sweep area of the jet is increased with the gradual expansion jet opening. The latter can make the cross section speed between the outlet of the tuyere and the opening of the tunnel more uniform, thus shortening the ventilation time required for the tunnel construction and speeding up the construction progress. A complicated three-dimensional numerical model for ventilation of underground oil and water seal cavern is established, and the problems that need to be solved in actual construction are simulated and calculated. The air flow direction and path of multi-section construction and multi-point linkage ventilation are obtained. The tunnel passage with weak air flow in the process of air flow organization is found, and the dynamic change process and law of harmful gas in underground cavern group are analyzed. In order to improve ventilation efficiency and eliminate harmful gas retention, an optimization scheme is put forward, and good ventilation effect is obtained, which provides important theoretical support for field construction.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE822

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