Risk identification and risk mitigation during metro station construction by enlarging shield tunnel combined with cut-and-cover method

Constructing a metro station by enlarging shield tunnels combined with a mining/cut-and-cover method provides a new method to solve the contradictions of construction time limits of shield tunnels and stations. As a new-style construction method, there are several specific risks involved in the construction process. Based on the test section of Sanyuanqiao station on Beijing metro line 10, and combined with the existing methods of risk identification at present, including a review of world-wide operational experience of similar projects, the study of generic guidance on hazards associated with the type of work being undertaken, and discussions with qualified and experienced staff from the project team, etc., the specific risks during the construction process of the metro station constructed by enlarging shield tunnels combined with the cut-and-cover method are identified. The results show that the specific risks mainly come from three construction processes which include constructing upper enclosure structures, excavating the soil between shield tunnels and demolishing shield segments. Then relevant risk mitigation measures are put forward. The results can provide references for scheme improvement and a comprehensive risk assessment of the new-style construction method.

A new method of measuring optical turbulence of atmospheric surface layer at Antarctic Taishan Station with ultrasonic anemometer

To find the optimal location for large-aperture telescopes is a goal of astronomy. Chinese Antarctic astronomy has begun to flourish in recent years, and it is an urgent need in basic astronomical work to measure and analyze the optical turbulence spatiotemporal distribution in the Antarctic region. We analyzed turbulence data measured by a mobile atmospheric parameter measurement system from 30 December 2013 to 10 February 2014 at Antarctic Taishan Station. Because there is a discrepancy between the refractive index structure constant Cn2 measured by an ultrasonic anemometer with a single-point temperature structure function method and by micro-thermometer, a new method to measure C,2 with a temperature spectrum method is proposed herein. Through comparing long-term continuous Cn2 data derived from ultrasonic anemometer with those via the new method and micro-thermometer, trend, magnitude and measured weak turbulence of-2× 10-16m-2/3 are generally satisfactory. The reason for the discrepancy in Cn2 measurement between the ultrasonic anemometer with the old method and micro-thermometer is investigated.

Feasibility evaluation for excavation of Naghshe Jahan Square subway station by underground methods

In recent years, in reaction to the increasing usage of urban areas, the excavation of underground spaces has been developed. One of the most challenging issues encountered by engineers is the construction of subway stations as large underground spaces at shallow depth with soft surrounding soils. In this paper, Naghshe Jahan Square subway station located in Isfahan, Iran, has been simulated by geomechanical fnite difference method(FDM). This station is located under important historical structures. Therefore, the ground displacement and surface settlement induced by the excavation of the subway station should be strictly controlled. Many of such problems are affected by selected excavation method. For these reasons, different underground excavation methods associated with construction have been studied. In this study, sequential excavation method and large-diameter curved pipe roofng method are used and the numerical results of the two methods are compared. The presence of groundwater table obliges us to choose special techniques for the stability of the ground around the subway station during construction; hence compressed air and ground freezing techniques are utilized in the simulations of the subway station. Finally, after choosing appropriate support systems, the large-diameter curved pipe roofng method with 1.5 m spacing between curved pipes is proposed.

Study on Rear-end Real-time Data Quality Control Method of Regional Automatic Weather Station

[Objective] The aim was to study the rear-end real-time data quality control method of regional automatic weather station. [Method] The basic content and steps of rear-end real-time data quality control of regional automatic weather station were introduced. Each element was treated with systematic quality control procedure. The existence of rear-end real time data of regional meteorological station in Guangxi was expounded. Combining with relevant elements and linear changes, improvement based on traditional quality control method was made. By dint of evaluation and relevant check of element, the quality of temperature and pressure was controlled. [Result] The method was optimized based on traditional quality control method, and it narrowed the effectiveness of real-time data quality control. The quality check of hourly precipitation applied relevant check of hourly minimum temperature, vertical consistency check of radar data, which can effectively improve the accuracy and credibility of hourly precipitation quality control. [Conclusion] The method was on trial for one year in the quality control of real-time data in the regional automatic meteorological station in Guangxi and had gained good outcome.

QUAD METHOD FOR IDENTIFYING RELATIVELY STABLE STATIONS

The QUAD(Quasi-Accurate Detection of gross errors) method which is originally developed to detect gross errors in the geodetic data is extended and used to select and identify relatively stable stations. The formulas and algorithm are described in detail. Some problems that should be noticed in the use of this method are discussed. Finally, this method is applied to some data observed in North China as an example.

Study on V_P/ V_S Variation Behavior in the Shanxi Region by the Wadati Single Station and Multi-earthquake Method

Based on arrival time data of seismic phases of ML≥2. 0 earthquakes measured at Shanxi Digital Seismic Network for the period from January 2001 to October 2014,V_P/ V_S in the Shanxi region is calculated using the Wadati single station and multi-earthquake method,and an investigation is conducted into the variation behavior of V_P/ V_S in the Shanxi region before and after the three earthquakes of MS≥4. 5 in 2010. Our study finds that abnormal V_P/ V_S appeared earlier at distant stations before all of the three earthquakes,which is at the time range from 6 months to 1 year before the earthquakes,and later at near stations,at the time range 10 days to 2 months before earthquakes. Therefore,it  s possible to narrow down the scope of the location in earthquake prediction from the distant and near station data. The calculations of Dongshan seismic station indicate that the size of the residual of the origin time has impact on the detail of V_P/ V_S variation,thus,appropriate thresholds should firstly be set for the residuals of origin time at each seismic station in practical application,to ensure scientific and steady V_P/ V_S calculations.

Electromagnetic response function for the semi-annual variations estimated by the single-station method using the night-time values of the geomagnetic fields

The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep gcomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper.

光伏电站理论发电功率的优化计算模型与方法

光伏电站理论发电功率计算结果的准确性直接影响弃光电量的统计,对电网调度及光伏发展规划影响重大。理论发电功率的传统计算方法有样板逆变器法和气象数据外推法,当样板逆变器的出力受到限制时,样板逆变器法计算结果不准确,而气象数据外推法参数众多且难以确定。针对上述问题,提出了一种光伏电站理论发电功率优化计算方法。首先,介绍了样板逆变器法和气象数据外推法的计算原理,并分析了两种方法的特点和不足。然后,基于光伏电站历史出力及气象信息,提出了改进样板逆变器法和改进气象数据外推法。在实际应用中,当弃光未发生或者在弃光初始阶段采用计算精度更高的改进样板逆变器法开展计算,当样板逆变器出力受到限制时,切换至改进气象数据外推法进行求解。最后,对国内某光伏电站在不同气象条件下开展仿真计算,验证了所提方法的合理性和有效性。

基于TOPSIS-Shapley值法的梯级水电站补偿效益分摊研究

针对流域内联合电站数目众多但利益分配存在纠纷的情况,旨在提出一种更为合理的梯级电站利益分配方法。基于Shapley值法和TOPSIS法,综合考虑电站贡献及电站对不同客观分摊方法的相对满意程度,建立TOPSIS-Shapley值法梯级电站补偿效益分摊模型,同时为解决Shapley值法在求解多利益主体梯级电站联合调度增益分配问题中的局限性,引入聚合降维思想。模型思路如下:将上游电站联合调度前后梯级发电效益的增量作为补偿效益,首先采取四种不同的客观分摊方法对电站特性参数指标进行计算,构成TOPSIS的基础决策矩阵,利用TOPSIS原理得出电站对各个分摊方法的相对满意度,同时采用联盟博弈理论,计算电站所有可能联盟方式下的发电效益,得到基于Shapley值的补偿效益分摊结果,最后将TOPSIS原理得出的分摊系数与由Shapley值法所得的分摊系数结合形成综合分摊权重,应用于黑河上游的八级电站补偿效益分摊中。工程应用实例表明:该方法不仅考虑了联盟电站对整体的边际贡献和各电站的分摊满意程度,且兼顾了电站的特性指标差异,合理量化和分配了各电站间的发电补偿效益,分摊结果公平合理、易被各方接受,可促进流域各级电站参与联合调度从而达到整体效益最大的目标,对于数量较多的梯级水电站补偿效益分配问题具有重要参考意义。

基于DEMATEL-ISM方法的水电站机组检修作业安全事故致因链分析

针对水电站机组检修作业种类和危险因素多、安全事故频发等问题,通过文献挖掘与专家访谈方式,对水电站机组检修作业安全影响因素类别进行了划分。基于DEMATEL-ISM方法,构建了安全事故致因多层次递阶ISM模型来确定事故致因因素层级,通过剖析事故致因因素的中心度和权重,挖掘关键致因因素和推求事故致因链的路径权重,厘定关键致因链。采用该模型对某水电站致因链进行了分析,结果表明,安全检查不到位为关键致因因素,“安全检查不到位→违规作业→设备的问题→粉尘、油漆等有害物质”为关键致因链。

黄土地区洞桩法地铁车站边桩和中柱的受力变形机理

[目的]为了确保黄土地区洞桩法车站施工过程中重要竖向承重构件的稳定性,需要对施工过程中边桩和中柱的受力变形机理进行研究,并对最不利受力阶段边桩和中柱提出变形控制措施。[方法]以西安地铁2号线何家营站为研究背景,通过数值模拟与现场监测的方法,对施工过程中边桩的水平位移、钢筋内力、水平土压力及中柱应变展开研究。[结果及结论]扣拱施作以及站厅层和站台层土体开挖是边桩水平位移最不利的三个阶段,在这些关键阶段施工时,应在结构内部架设钢支撑并适当加固已扰动的地层;在桩梁和扣拱施作中,边桩主筋承受轴向压力,而在站内剩余土方施工阶段,边桩背土侧的钢筋由轴向压力逐渐转化为轴向拉力,且随着边桩埋深的增大,钢筋的轴向拉压力增长变缓;在扣拱初期支护施作中,土压力在边桩埋深6.6 m处达到最大值34.5 kPa,且随着边桩埋置深度增大,边桩的桩侧压力增长速率显著,因此车站内侧的土方开挖是控制边桩迎土侧土压力大小的关键阶段,必要时对桩后土体进行注浆加固有利于提高桩基的承载力;中跨扣拱施工时,中柱的应变呈现出先减小、后增大的趋势。

站城融合背景下的高铁站域空间利用一体化评价——以武汉市为例

在站城融合的背景下,交通枢纽站成为承载多种功能的重要的复合型公共空间,为使高铁站域空间成为城市发展中具有吸引力的核心部分,对新一代高速铁路枢纽提出了站城一体化的要求,以更好地满足人们对交通、娱乐、休闲的需求。该文以武汉市三个主要高铁站为例,依托地理信息科学(GIS)技术,结合多源大数据,通过借鉴日本站城一体化的发展模式,从交通可达性、设施便利性、功能混合度和土地开发强度四个维度建立高速铁路枢纽空间利用一体化评价指标体系,对铁路枢纽一体化水平进行了综合系统的评价。相关结果对高铁站的建设与完善提供了借鉴。

充填站荷载作用下露天坑边坡稳定性分析

某铁矿生态修复工程采用尾砂胶结固化方式对露天采坑进行回填,计划在露天坑周边建设充填站,为论证边坡及充填站安全可靠性,本文采用极限平衡分析和数值模拟方法,对充填站荷载作用下的边坡稳定性进行了计算分析。计算结果显示,该充填站所处的边坡在回填至-354 m时为基本稳定,在充填至-300 m工况下处于稳定状态,为确保边坡及充填站安全,建议加强该充填站所在区域边坡监测,确定所在区域边坡稳定前提下进行建设。

基于24Model-D-ISM的地铁站火灾疏散影响因素研究

为预防地铁站火灾事故,深入了解地铁站火灾人员疏散影响因素间的内在联系与层次结构,基于第6版“2-4”模型(24Model)分析63起地铁站火灾疏散事故,充分考虑各个因素之间的交互作用,提取19个影响地铁站人员疏散的关键因素,建立地铁站火灾人员疏散影响因素指标体系;采用算子客观赋权法(C-OWA)改进决策试验与评价实验法(DEMATEL),确定地铁站火灾人员疏散的重要影响因素;在此基础上,采用解释结构模型(ISM)分析各个因素间的层次结构及相互作用路径,构建地铁站火灾人员疏散影响因素的多级递阶结构模型。研究结果表明:疏散引导、恐慌从众行为、人员拥挤为地铁站火灾人员疏散的关键影响因素;地铁站火灾人员疏散受表层因素、中间层因素、深层因素共同作用的影响,其中,疏散教育与培训、设施维护与检查、疏散预案等因素是根源影响因素,重视根源影响因素的改善有利于从本质上预防和控制事故的发生。

布仑口水电站冲击式机组柔性电制动技术应用

为保证布仑口水电站机组停机过程中轴承油膜不被破坏,确保机组瓦温运行在安全范围内,解决制动停机问题,文章以新疆布仑口水电站为背景,介绍了冲击式机组柔性电制动技术的工程应用,重点介绍了布仑口电站冲击式机组停机方式、柔性电制动停机原理、电制动主回路接线形式、电制动流程、电制动系统主要设备参数,并对柔性电制动技术的基本思路和工程实现进行探讨。

北斗坐标框架解算中的IGS参考站选站方法研究

首先从ITRF2020框架中筛选能接收北斗信号的站点;然后从数据完整性、卫星可见性、多路径误差等方面对站点观测数据质量进行分析,设定相应标准进行筛选;最后基于格网法提出一种既考虑均匀性又考虑数据质量和站点稳定性的选站方法。利用该方法优选72个全球均匀分布的测站作为北斗坐标框架解算中的IGS参考站。

一种双工位NEG吸气性能测试装置设计

文章设计了可选择定压法或定容法测量非蒸散型吸气剂(NEG)吸气性能的测试装置,装置设计有两个结构对称的测试工位,可同时对两个测试样品进行预处理和性能测试,装置结构设计合理紧凑,测试效率高。测试装置可直接通过软件输出吸气速率和吸气量等性能参数。测试结果表明该装置本底真空度高,其中样品室真空度优于1×10^(−7) Pa,漏放气速率小于3×10^(−7) Pa·L/s;测试数据精度高且可靠,其中吸气速率测量精度达1 mL/s,吸气量测量精度达1 Pa·mL。

适用于空间站环境的脑力疲劳检测方法的研究

目的针对航天员在轨期间可能出现的脑力疲劳问题,研究一种适用于空间站环境的脑力疲劳检测方法。方法地基实验采用36h睡眠剥夺实验诱发脑力疲劳状态,采集45名受试者的脑电图(EEG)数据和问卷评分,计算与脑力疲劳相关的一系列EEG特征并运用随机森林分类器构建脑力疲劳检测方法,以区分脑力疲劳水平。结果在地基实验和天基实验的数据中均取得85%以上的平均准确率,各项评价指标趋势一致。结论基于EEG信号的脑力疲劳检测方法能够应对环境及任务的差异,在地基实验与天基实验中均展现出准确稳定的性能,未来在空间飞行环境中的应用具有一定可行性。

水电主导现货市场优化出清研究

针对传统以购电经济性为唯一目标的市场出清中梯级水电一边缺水一边弃水的水-电不匹配问题,本研究结合梯级水电运行特性,提出一种水力、电力、价格3因素耦合的出清方法。首先,梳理了梯级水电出清后缺水和弃水两种水-电不匹配的工况,提出用水-电耦合度指标来度量水量与电量匹配的程度,并给出了水-电耦合度的计算方法。其次,建立了适用于水电主导电力市场的水力、电力和价格耦合出清模型,设计了购电成本最小化和水-电耦合度最大化两个目标函数。为了提高模型求解效率,提出模型结构分层、搜索空间缩减和计算时段合并的模型求解综合降维策略,并基于价格排序-粒子群耦合优化算法实现模型求解。最后,以四川省串并混联开发的“3梯8站”组成的虚拟市场进行日前模拟出清。结果表明:与传统以经济性为唯一目标的出清模型相比,水-电-价耦合出清模型的购电费用不变,但水-电耦合度提高了1.57%,证明水-电耦合度最大化目标的加入不会增加购电成本,但对减少出力不足、提升出清结果的可执行率和降低弃水都有显著成效;所提求解策略降低了模型复杂度,提高了求解效率,为解决梯级水电现货市场出清中水-电-价的不耦合问题提供了新思路。

基于响应面法的泵站导流墩开孔参数优化

针对扩建泵站工程进水建筑物内存在的偏流、漩涡等不良流态,工程往往采取布置导流墩的方法来优化流态,但其结构参数通常根据经验进行调整,难以达到最优效果。为了确定导流墩开孔的最佳结构参数,研究将导流墩的开孔长度、宽度、高度和间距作为设计变量,基于中心组合设计法进行试验方案设计,以轴向流速均匀度作为评价指标,构建响应面模型进行优化分析,确定了导流墩开孔的最佳参数组合。在最佳参数组合下进行数值模拟,发现实际值与响应面模型预测值误差仅为0.33%,轴向流速均匀度相较于原方案提升了11.17%,显著改善了前池流态。研究结果表明建立的响应面模型能够反应评价指标和设计变量的关系,并且可以将该方法应用到整流措施的结构参数优化中。