膜袋注浆桩在软基处理应用中的试验研究

在介绍膜袋注浆桩及其加固机理的基础上,通过现场实体试验,对注浆过程中孔隙水压力变化进行了分析,并结合注浆量统计分析、现场开挖检验和钻孔抽芯检验对成桩状况进行了研究,结果表明直径为40cm的单个注浆孔挤土效应影响范围可达5m,在2m范围内挤土效应衰减较快,而注浆后可形成连续、强度较高的桩体。     

复合地层土压平衡盾构掘进参数模拟分析研究

复合地层特别是软硬交互地层的盾构掘进参数模拟与预测理论及方法研究,目前还处于薄弱阶段。基于Terzaghi松动土压力模型与CSM(科罗拉多矿业学院)模型,对广州地铁3号线大石—汉溪区间不同风化程度混合岩地层的土压平衡盾构掘进表现分别进行模拟分析,结果基本符合实际的掘进表现,但在贯入度大于20 mm/r的硬岩掘进情况下推力及扭矩模拟值与实际值存在较大正负差异。针对这种正负差异情况,分析可能产生的原因。通过对软硬交互复合地层的盾构受力分析,模拟计算在软硬地层各占50%情况下的推力与扭矩值,结果表明,总推力和扭矩的模拟值均在实际值范围内,验证了采用的综合考虑软土和硬岩模拟分析结果的复合地层掘进参数模拟分析方法的有效性。     

隧道涌突水的原因和预测预报方法

复杂地质条件下的隧道涌突水是常见的施工灾害之一,严重威胁着现场施工安全及进度。为了能更准确地预测预防涌突水的发生,减少危害,从常规地质方法角度进行研究,从地下水补给、流通、存储和水压等几方面进行系统分析,解析涌突水的原因以及可能性;对几个隧道涌突水事件发生的原因进行探索,并结合理论分析和实践经验,提出一些勘察、预报时容易忽视的地方,以引起注意。     

城市轨道交通工程控制测量建网策略

为了解决城市轨道交通大规模、大范围建设过程中导致的测量控制网的整体性差、新旧坐标系统不匹配等问题,分析了全国城市轨道交通工程建设的新趋势,根据工作经验,总结了目前城市轨道交通工程测量工作面临的新问题,有针对性地提出了城市轨道交通工程地面控制测量建网策略。实践证明,通过实施这些策略,能够很好地解决目前城市轨道交通建设所面临的诸多测量问题。     

黄土盾构隧道膨润土泥浆渣土改良技术研究

为了解决黄土地层中土压平衡盾构施工地铁区间隧道时出现的出土困难、土仓压力难以建立以及刀具温度过高等问题,采用膨润土、泡沫对渣土进行改良才能保证盾构掘进效果。采用正交试验法进行了膨润土泥浆优化试验与泡沫优化试验。通过膨润土泥浆优化试验找到了适合黄土地层的膨润土改良剂及膨润土泥浆的最优体积分数。通过泡沫优化试验找到了泡沫性能与发泡剂溶液最佳体积分数的关系,本文研究成果在实际工程中得到了成功应用,以期为类似工程提供借鉴与参考。     

盾构隧道施工对既有铁路轨道与排洪涵管影响的数值分析

以福州地铁l号线的罗汉山站—福州火车站区间段盾构隧道工程为依托,采用有限元程序MIDAS,对近距离双线平行盾构掘进过程进行动态模拟,揭示盾构新隧道施工对既有铁路轨道和排洪涵管沉降产生的影响,得到了铁路轨道和涵管沉降曲线。计算结果表明,列车数量、隧道注浆程度、地层损失率等因素对铁路轨道和排洪涵管沉降有较大影响。     

浅谈地源热泵技术

阐述地源热泵技术的概念。介绍地源热泵系统的组成部分、工作原理和分类,分析地源热泵系统的特点和实际应用情况。提出地源热泵这种可再生能源在我国节能降耗、生态环保、可持续发展中具有广阔的发展和应用前景。     

Modeling taxi drivers’ decisions for improving airport ground access: John F. Kennedy airport case

Taxi service is an important component of airport ground access, which affects the economic competitiveness of an airport and its potential positive impact on the surrounding region. Airports across the globe experience both taxi shortages and excesses due to various factors such as the airport’s proximity to the city center, timing and frequency of flights, and the fare structure. Since taxi drivers are independent entities whose decisions affect the taxi supply at airports, it is important to understand taxi drivers’ decision mechanisms in order to suggest policies and to maintain taxi demand and supply equilibrium at the airports. In this paper, New York City (NYC) taxi drivers’ decisions about airport pick-ups or cruising for customers at the end of each trip is modeled using logistic regression based on a large taxi GPS dataset. The presented approach helps to quantify the potential impacts of parameters and to rank their influence for policy recommendations. The results reveal that spatial variables (mainly related to proximity) have the highest impact on taxi drivers’ airport pickup decisions, followed by temporal, environmental and driver-shift related variables. Along with supplementary information from unstructured taxi driver interviews, the model results are used to suggest policies for the improvement of John F. Kennedy (JFK) airport’s ground access and passenger satisfaction, i.e. the implementation of taxi driver frequent airport server punch cards and a time-specific ride share program.     

基坑上跨盾构隧道实测数据分析及保护研究

以某绕城高速公路深基坑上跨运营盾构隧道工程案例为背景,首先以南半幅深基坑违规施工为切入点,通过现场监测、检测与三维扫描普查等实测成果,佐证违规施工对盾构隧道的不利影响程度,其次通过修正惯用法理论计算及Ansys建模分析,评估隧道结构横断面及纵断面的安全性能与安全冗余储备,再次以优化保护措施的北半幅施工为比对研究对象,通过现场实测数据证明分幅、分段、跳仓、限时开挖,增加板凳桩桩长,缩小桩间距,加大盖板厚度,实施土体填充注浆等措施可减少开挖期及工后盾构隧道隆起量,可以缩短工后隆起时间。据此,提出基坑上跨运营盾构隧道在设计、施工相关建议,为该类保护区外部作业及保护工作提供参考。     

Preference-based evolutionary algorithm for airport surface operations

In addition to time efficiency, minimisation of fuel consumption and related emissions has started to be considered by research on optimisation of airport surface operations as more airports face severe congestion and tightening environmental regulations. Objectives are related to economic cost which can be used as preferences to search for a region of cost efficient and Pareto optimal solutions. A multi-objective evolutionary optimisation framework with preferences is proposed in this paper to solve a complex optimisation problem integrating runway scheduling and airport ground movement problem. The evolutionary search algorithm uses modified crowding distance in the replacement procedure to take into account cost of delay and fuel price. Furthermore, uncertainty inherent in prices is reflected by expressing preferences as an interval. Preference information is used to control the extent of region of interest, which has a beneficial effect on algorithm performance. As a result, the search algorithm can achieve faster convergence and potentially better solutions. A filtering procedure is further proposed to select an evenly distributed subset of Pareto optimal solutions in order to reduce its size and help the decision maker. The computational results with data from major international hub airports show the efficiency of the proposed approach.