基于Civil 3D的三维地质覆盖层建模技术及应用

Civil 3D作为一个面向岩土勘察行业BIM设计及应用的解决方案,已成为三维地质建模实现技术之一。针对水运工程勘区场地覆盖层不同工程地质特点,采用"点-面-体"三维地质模型的构建思路,分别提出单一和复杂覆盖层地质模型建模方法。结合某船闸工程案例,通过覆盖层边界线导入、曲面分割、曲面围合等技术,实现场地三维地质模型表层岩土体精细化表达,准确直观地展示了勘区覆盖层地质发育与分布情况。研究成果对于后续土方量计算、基坑开挖设计等岩土勘察BIM应用具有重要实践意义。     

弱电系统后备电源整合与智能化计时管理

提出城市轨道交通采用弱电系统后备电源整合与智能化计时配电管理的设计理念,并通过在深圳地铁3号线中的应用,表明该系统具有更高的适应性、可用性、可靠性、可维护性和可扩展性,该系统整合后。可大幅度节省建设投资、降低运营成本、节省能源,而且有利于环保。     

TDCS/CTC系统路局中心网络防火墙桥接模式

TDCS/CTC系统作为铁路运输指挥的重要行车设备,系统网络安全是保障其正常运行的因素之一,防火墙是重要的网络安全设备。简单介绍防火墙在TDCS/CTC系统中应用情况及接入模式,并根据TDCS/CTC系统的特点详细分析中心网络的2种防火墙接入模式(路由模式和桥接模式)及透明桥接模式的优势。     

水上栈桥和平台在人造覆盖层中的优化设计

研究目的:通过分析人造覆盖层中入岩深度和不同边界条件下结构的整体稳定性,提供深水裸岩河床条件下人造覆盖层中水上栈桥和平台的优化设计方法,确保其安全性和可靠性。研究结论:(1)为减少爆破工作量,裸岩河床人造覆盖层中可以采用短桩形式,且短桩条件下采用"拉列琴假定"计算的入岩深度可以确保其安全性和可靠性;(2)因无法准确计算人造覆盖层对栈桥桩和平台桩的侧向抗力,桩的底部约束可按铰结和固结两种方式计算,实际情况介于这两者的计算结果之间;(3)若栈桥桩与平台桩在独立状态下不能满足安全性和可靠性,应增加二者之间的连接系,连接系的规格、数量和位置需通过整体强度及稳定性分析确定。     

干燥粉细砂层大断面斜井转入正洞施工技术

大西铁路客运专线干庆隧道3号斜井转入正洞施工中,成功运用了梯形断面弧形巷道垂直挑顶直接转入正洞的施工方案。就干燥粉细砂层地质,针对不同部位综合采取了密排超前小导管注改性水玻璃加固砂层施工技术、多台阶分部开挖法、侧壁超前旋喷咬合桩加固砂层施工方法、强刚度特殊结构门架技术和控制支护脚部下沉施工技术,分别阐述了其施工工艺流程和技术要点。该技术可对类似地质条件下的隧道施工和控制流砂、涌砂甚至砂层滑塌等现象提供指导和借鉴。     

Distribution of void fraction in bubbly flow through a horizontal channel: Bubbly boundary layer flow, 2nd report

A method of enveloping the hull with a sheet of microbubbles is discussed. It forms part of a study on means of reducing the skin friction acting on a ship's hull. In this report, a bubble traveling through a horizontal channel is regarded as a diffusive particle. Based on this assumption, an equation based on flow flux balance is derived for determining the void fraction in approximation. The equation thus derived is used for calculation, and the calculation results are compared with reported experimental data. The equation is further manipulated to make it compatible with a mixing length model that takes into account the presence of bubbles in the liquid stream. Among the factors contained in the equation thus derived, those affected by the presence of bubbles are the change of mixing length and the difference in the ratio of skin friction between cases with and without bubbles. These factors can be calculated using the mean void fraction in the boundary layer determined by the rate of air supply into the flow field. It is suggested that the ratio between boundary layer thickness and bubble diameter could constitute a significant parameter to replace the scale effect in estimating values applicable to actual ships from corresponding data obtained in model experiments.List of symbols a ₁ proportionality constant indicating directionality of turbulence - B law-of-the-wall constant - C _f local skin-friction coefficient in the presence of bubbles - C _f0 local skin-friction coefficient in the absence of bubbles - d _b bubble diameter (m) - g acceleration of gravity (m/s²) - j _g flow flux of gas phase accountable to buoyancy (m/s) - j _t flow flux of gas phase accountable to turbulence (m/s) - k ₄ constant relating reduction of liquid shear stress by bubble presence to decrease of force imparted to bubble by its displacement due to turbulence - l _b mixing length of gas phase (m) - l _m mixing length of liquid phase (m) - l _mb diminution of liquid phase mixing length by bubble presence (m) - Q _G rate of air supply to liquid stream (l/min) - q _/g velocity of bubble rise (m/s) - 2R height of horizontal channel (m) - T _* integral time scale (s) - U _m mean stream velocity in channel (m/s) - U friction velocity in channel (m/s) - V volume of a bubble (m³) - u, ¯ v time-averaged stream velocities inx- andy-directions, respectively (m/s) - u, v turbulent velocity components inx- andy-directions, respectively (m/s) - v root mean square of turbulence component in they-direction (m/s) - root mean square of bubble displacement iny-direction with reference to turbulent liquid phase velocity (m) - y displacement from ceiling (m) - local void fraction - _m mean void fraction in boundary layer - _m constant relating local void fraction to law-of-the-wall constant - _t reduction of turbulent stress (N/m²) - law-of-the-wall constant in turbulent liquid region in absence of bubbles - ₁ law-of-the-wall constant in turbulent liquid region in presence of bubbles - ₂ law-of-the-wall constant in gas phase - _m constant indicating representative turbulence scale (m) - viscosity (Pa × s) - v kinematic viscosity (m²/s) - density (kg/m³) Suffixes G gas - L liquid - 0 absence of bubbles     

引松供水工程岩溶及软弱破碎地层敞开式TBM施工技术

引松供水工程四标段隧洞TBM法施工长度约17 km,其中7 332 m主要穿越灰岩(岩溶)、炭质板岩、断层等软弱破碎地层。为解决TBM在该类地层中掘进时TBM偏机、栽头、刀盘被糊、被卡、涌泥涌水、收敛变形引起设备被卡等难题,通过资料查阅、调研国内外现有TBM施工案例、专家咨询研讨等,对比研究多种方案;结合工程实践,提出TBM超前地质预报、钢拱架、钢筋排和喷射混凝土联合及时支护等一系列确保TBM连续施工的方案与措施。经工程验证,该方案与措施能够很好地保证TBM在岩溶及软弱破碎地层的连续掘进,为工程的顺利实施奠定了坚实的基础。本文研究得出了一系列理论及参数,可为类似工程提供借鉴和参考。     

新型酸性水玻璃注浆材料的研究与应用

针对城市地铁穿越砂层时注浆预加固的材料问题,研究磷酸-水玻璃注浆材料的凝胶时间、凝胶形态和砂土固结体强度的影响因素以及工程应用材料配比,设计磷酸-水玻璃注浆材料室内凝胶性能试验和砂土固结体强度试验,并与传统的硫酸-水玻璃注浆材料进行系统性对比,最后根据室内试验选择合适的材料配比进行现场注浆试验。试验结果表明:1)磷酸-水玻璃混合液中,当磷酸的掺量增大时,磷酸与水玻璃的体积比增大,混合液的pH值减小,凝胶时间增大,存在一一对应的关系;2)磷酸-水玻璃混合液的pH值是磷酸-水玻璃浆液凝胶时间和凝胶形态的决定性因素;3)磷酸-水玻璃浆液中磷酸质量分数、水玻璃波美度和混合液体积比分别变化时,加固体抗压强度稍有变化,影响较小。     

湍流激励下简支平板振动特性的解析法研究

解析法基于随机激励理论,采用湍流脉动压力的Corcos模型作为输入,结合考虑流固耦合时平板的频响函数,求解得到平板振动速度的自功率谱密度。计算结果同已有文献吻合较好,证明了解析法的正确性。同时研究结果表明：湍流激励下平板的振动特性体现了平板本身的固有特性;随着来流速度的增大,平板振速的均方谱密度幅值按一定的数值关系增大。     

大直径地铁盾构隧道下穿高铁明挖隧道方案研究

天津某地铁盾构区间超深埋隧道下穿京津城际线解放路明挖隧道,工程处于软土地层,地质条件差,工程风险大。为探究盾构下穿对高铁明挖隧道的影响,首先对高铁明挖隧道现状进行调查,对外径6.6 m双线盾构依次下穿高铁明挖隧道4种方案的优缺点进行比选分析,并运用有限元数值模拟手段对优选方案进行分析计算。结果表明:(1)高铁明挖隧道现状良好,最大不均匀沉降为0.7 mm;(2)盾构下穿绕避高铁明挖隧道地连墙方案可行性及安全性均优于其他方案,该方案对高铁既有结构不会造成直接破坏,模拟计算结果能够满足相关规范要求(沉降<2 mm),方案安全可行。