一种新型非饱和土温控三轴试验系统的研制与初步应用

为研究温度对非饱和土水力、力学和声学性质的影响,自主研发一套带有弯曲元和精密体变量测的温控式三轴仪。本设备通过在GDS应力路径非饱和土三轴试验系统中增设温控内压力室的方式,实现了对温度变化的精确控制及量测;通过将压差传感器与温控内压力室相结合,实现了温度变化情况下试样体变的精确量测;同时增设了一套弯曲元测试系统,增加了仪器的功能,实现了温度变化情况下对试样实时波速的测试。通过对杭州湾粉细砂土开展4个温度水平的三轴剪切试验以及同一温度水平下的波速测试,结果表明:新仪器能够稳定的控制温度变化条件、精确测量温度变化条件下试样的体变以及测量温度变化条件下试样的实时波速,初步检验了仪器性能的可靠性。该设备整体结构简单,拆装方便,可实现常规非饱和(饱和)土试验与温控非饱和(饱和)土试验之间自由切换,互不干扰。设备研制的成功,将为非饱和(饱和)土的热-水-力-声耦合特性的研究提供方便有效的测试装置。     

隧道岩溶管道型突涌水动态演化特征及涌水量综合预测

建立了隧道岩溶管道型突涌水模型,进行了突涌水过程中动态演化特征分析,结果表明揭露岩溶管道型突涌水的动态演化无明显的时间效应,但空间特征呈现阶段演化的规律,突涌水区域可分为三种典型流速演化区域:管道内部的近似高速稳定区,隧道与岩溶管道临界面附近的流速升高区以及隧道内部灾害水体的衰减–低速稳定区。基于管道内部区域流速动态衰减规律,提出了基于数值分析法和极限(离散)解析法的涌水量综合预测方法,形成揭露岩溶管道型突涌水的涌水量预测体系,并设计了相应的模型试验,进行了涌水量的实时监测,监测结果验证了涌水量综合预测方法的合理性。     

协同意义下的建筑工程变更问题分析

大多数文献对工程变更持负面看法,但无法解释工程变更为什么在建筑工程中普遍存在。建筑工程系统是复杂自适应系统,在界面协同作用下,能够产生涌现效果并以工程变更的形式存在且积极影响工程进展。除涌现因素外,工程变更还包括常规性和消极性变动因素,因此,对工程变更应采取协同管理和合同管理相结合、以协同管理为主导的策略。     

城市化进程中城市社区变迁探究--以深圳为例

随着城市化进程的不断加快,我国城市社区的结构和功能发生着越来越深刻的变化,也带来了众多的社会问题和社会矛盾。本文以我国快速城市化典型代表的深圳市为例,探讨城市社区的发展、变迁和类型的分化,旨在为规划城市社区发展、制定社区政策和探索谋划社区治理新路提供积极的现实指导。     

A flood risk assessment to municipal infrastructure due to changing climate part II: case study

Flooding often has devastating consequences. It is important to understand the evolution of these risks as climate changes. Municipal infrastructure is designed using historical data that no longer accurately represents current climate conditions, indicating infrastructure may underperform. The purpose of this study is to apply a new methodology for the assessment of climate change caused flood risk by Bowering et al. (2013) to the City of London, Ontario, Canada. Floodplain maps derived from climate, hydrologic and hydraulic analyses provide direct input into risk assessment procedure. Inundated infrastructure and high risk areas are identified in tables and maps for two climate and two hydraulic scenarios. Results indicate the most critical flood scenario is the 100 year climate change upper bound and high risk is driven by expensive infrastructure located in the floodplains. Results of the study are used as the support for climate change adaptation policy development and emergency management.     

Statistical evaluation on storm sewer design criteria under climate change in Seoul,South Korea

This study conducted statistical analysis under both stationary and non-stationary climate using rainfall data measured in Seoul, South Korea. The 50 year annual maximum rainfall data were analysed with generalised extreme value distribution and Gumbel distribution. Possible rainfall changes were predicted with nonstationary forms of the two distributions, considering time variable location parameters. The current storm sewer design criteria were assessed by reflecting climate change implications and expected lifetime performance. Expected return periods were reduced to 4.67, 8.66, 19.16 and 23.53 years for the current 10 min - 5, 10, 30 and 50 years. The newly suggested design criteria of 5, 10, 30 and 50 yr return period storm events were 5.3, 12, 48 and 107 years for the 10 min duration for a 50 year lifetime expectancy.     

Sensitivity analysis of municipal drinking water distribution system energy use to system properties

Municipal Drinking Water Distribution Systems (MDWDSs) consume a significant quantity of energy to transport water, thereby exacerbating greenhouse gas emissions and global climate change. The current study is a sensitivity analysis that uses a network solver to quantify energy savings due to the alteration of three system properties—system-wide water demand, storage tank parameters (maximum water level, diameter, elevation), and pumping stations (horsepower, number of boosters, and their locations) of seven diverse MDWDSs. It was found that a 50% reduction in water demand, main pump horsepower, and booster horsepower resulted in an average energy savings of 47, 41, and 9.5% respectively, for the seven systems analyzed. Other properties examined showed insignificant savings. Even though an individual system analysis is more conclusive, this sensitivity analysis can guide optimization studies to focus on the most sensitive properties.     

Theorizing Inside Activism: Understanding Policymaking and Policy Change from Below

To further our understanding on policymaking and policy change we need to recognize the significance of individual key actors in policy and planning processes. This article theorizes on the characteristics and policy influence of inside activism in which individual public officials act strategically from inside public administration to change government policy and action in line with a civic engagement and value commitment. Based on initial empirical findings from Swedish local government, we argue that inside activism is empirically relevant but not satisfactorily covered by other key actor concepts. We theorize that inside activism is 1) dualistic: open, deliberative, consensus-seeking and tacit, tactical, power-driven; 2) influential through informal networking inside and outside of government; and 3) dynamic as it varies over time and between critical situations. Due to current trends in society and public administration (e.g. governance), we expect inside activism to be increasingly relevant and we encourage further theoretical, empirical as well as normative research and discussion on this phenomenon.     

External corrosion to concrete sewers: a case study

The aim of this study was to investigate the deterioration of concrete sewers and identify responsible factors; this investigation was a part of an ongoing asset evaluation for Rennes (France). The sewer studied was a 300 mm spun concrete pipe laid in 1992. Core samples (D 28 mm, L 40 mm) were taken from different areas of a pipe (invert, crown and side wall) and analysed to quantify the condition of the concrete and the extent of damage to the internal and external surface of the pipe. Physical and mechanical properties of the material were characterised. The depassivation of the concrete was measured by testing with a phenolphthalein solution. The study showed that in this particular case the external corrosion was extensive with minimal internal corrosion.

It is proposed that the corrosion was possibly linked to the use of a contaminated backfill or organic acids in the ground water. Recommendations are proposed concerning the direction of future research.     

Regional loss estimation due to hurricane wind and hurricane-induced surge considering climate variability

This paper presents a framework to assess the potential hurricane damage risks to residential construction. Studies show that hurricane wind, frequency and/or hurricane-induced surge may change as a result of climate change; therefore, hurricane risk assessments should be capable of accounting for the impacts climate change. The framework includes a hurricane wind field model, hurricane-induced surge height model and hurricane vulnerability models. Three case study locations (Miami-Dade County, FL; New Hanover County, NC and Galveston County, TX) are presented for two types of analyses: annual regional loss estimation and event-based regional loss estimation. Demographic information, such as median house value and changes in house numbers, and distribution of houses for different exposures, is used to estimate the time-dependent probability of damage with or without possible climate change-induced change in wind speed, frequency and/or surge height. Through both analyses, it was found that climate change may have a significant impact on regional hurricane damage losses.