Reinforcing cycles involving inter- and intraorganizational paradoxical tensions when managing large construction projects

In recent years, scholars have shown a growing interest in combining control and flexibility when organizing and managing large construction projects, in contrast with the traditional focus on control. Prior research recognizes that there is a paradoxical tension between control and flexibility, meaning that, while both approaches make sense individually, they appear impossible to combine. Large construction projects are interorganizational, which means that tensions between interorganizational control/flexibility coexist with tensions between intraorganizational direction/empowerment, but the interplay and possible reinforcing cycles involving the two tensions have rarely been investigated in prior research. A multiple case study of four large construction projects with three rounds of interviews show how intraorganizational direction/empowerment can influence interorganizational control/flexibility and vice versa, and demonstrate both vicious and virtuous reinforcing cycles that involve the two types of tensions. Therefore, contributing to the project management and construction management literature, it is argued that employing a systemic approach when studying interorganizational projects is essential. A systemic paradox perspective can reveal interdependencies between tensions at different organizational interfaces, improve the understanding of how individuals in all managerial positions interplay, and explain how reinforcing cycles emerge and develop; this is important to recognize when organizing, staffing and managing large construction projects.     

工程配套小型石料矿山复杂环境开采爆破技术

建设工程配套石料矿山相比传统以取得矿产品为目的的采石场具有周边环境复杂、施工强度高、全寿命周期短、工程质量要求灵活多变、爆破安全警戒工作量大等特点。以普陀区六横岛中远船务二期工程石料（宕渣）矿爆破开采工程为例，介绍了该类矿山开采爆破的设计施工技术要点及施工经验，有效解决了建设工程配套小型石料矿山复杂环境开采爆破存在的一些问题，对于类似工程实践有一定的借鉴价值。     

雨林地区米拉多铜矿排土场碾压堆石坝施工技术

随着社会经济的发展，如何合理、有序、经济、环保地处理弃土弃渣已成为强降雨地区土石方项目亟需解决的问题。而对于雨林地区土石方工程往往需要布设大面积的排土场进行弃土弃渣，弃土弃渣存在“量大、集中”等特点。为保证弃土有效容量，排土场往往设置在沟谷中，雨林地区排土场如何保证地基处理、渗流层施工、分层填筑碾压是坝体施工质量控制的关键所在。以厄瓜多尔米拉多铜矿采矿工业场地工程项目为例，该项目存在土石方开挖工程量大，项目面临雨季长、高雨频等突出气候特点。项目排土场设计为碾压堆石坝，坝体整体高度84.8 m，坝体填筑石方达27.8万m3。简要介绍了该工程1 095 m排土场坝体施工的特点和难点，叙述坝体施工过程中采取的主要关键技术，为类似的工程施工提供借鉴。     

The roles of conceptual modelling in improving construction simulation studies: A comprehensive review

The conceptual modelling phase of simulation studies has proven to be effective in enhancing the impact of simulation modelling in different domains. However, this simulation phase did not receive much attention in the construction simulation domain. The objective of this paper is to identify the roles that conceptual modelling can play in advancing the engagement, accuracy, and adoption (among other things) of discrete-event simulation studies in construction. In this paper, a Systematic Literature Review (SLR) is conducted, which involves a comprehensive search of databases and researchers’ profiles to identify journal papers, conference articles, books, and theses that have reported the benefits of conceptual modelling for discrete-event simulation studies. The review resulted in 82 documents that were published from 2000 to 2020. Results indicate that the benefits of conceptual modelling include facilitating communications between stakeholders, capturing sufficient information for the simulation model, improving the quality of simulation models, guiding other simulation modelling activities, and facilitating verification and validation of simulation models. By linking these benefits to the current research agenda in construction simulation, this paper shows the significance and potential of the conceptual modelling phase to enhance the impact of discrete-event simulation studies in construction.     

Teaching construction sciences with the integration of BIM to undergraduate architecture students

This study aims to test two hypotheses: teaching building information modeling (BIM) in relation to construction science provides students with a remarkable understanding of the nature of construction science (Hypothesis 1), and if the student has positive attitude toward the use of the BIM program, then efficiency by which construction science is taught by its means is improved (Hypothesis 2). Results and process of a case study with a novel teaching methodology were discussed in terms of the benefits of the students. A questionnaire study was conducted on the student group with which the case study was performed to test each student's attitude. Results were evaluated statistically. When BIM is integrated with the teaching of basic construction courses within architecture degree programs, the students understood the building system principles simply and effectively. As a result of the statistical analysis, the students find the applied method effective. Moreover, their attitude toward BIM affects the process.     

Preliminary results of hand arm vibration (HAV) exposures of chipping hammer operators in tropical weather: Analysis of exposures and protective gloves

Objectives of this study are to analyze the HAV exposures of chipping hammer operators from field measurements and to investigate the potential of various types of gloves in reducing the exposures. HAV exposures of twelve male operators were measured at four different operating conditions: bare hand, wearing normal workman gloves, wearing heavy workman gloves and wearing vibration reducing gloves. From the measurements, 8 h exposure values were determined and assessed against standards. The total vibration values were determined and effectiveness in vibration attenuation by gloves was compared. It was found that all most all operators, HAV exposure levels exceeded the exposure action value (EAV) and about 83% of the operators exceeded the exposure limit values (ELV). A reduction in the total vibration magnitude was observed with protective gloves: 8.3% with normal workman gloves, 14.6% with heavy workman gloves and 40% with vibration-reducing gloves. To confirm the effectiveness of the vibration reducing gloves, further field investigations are required with simultaneous measurements by considering parameters affecting HAV (i.e., hand forces and postures).     

Assessing the impact of COVID-19 and safety parameters on energy project performance with an analytical hierarchy process

COVID-19 has destabilized the global economy, disrupted the lives of billions of people globally, and caused the workforce to suffer. Furthermore, the spread of this disease has caused most nations to impose strict lockdown regulations and shutdown most industries. This study aimed to highlight the key issues of energy project performance alongside construction activities that were halted during the COVID-19 outbreak to follow social distancing, lockdown, and public safety parameters. A questionnaire survey was administered to accomplish the purpose of this study. The responses of 42 energy project professionals and experts were evaluated using the analytical hierarchy process (AHP) for group decision-making. AHP shows that the biggest influences on project performance during COVID-19 pandemic were government measures and personal factors. The findings provide insight to support energy project planning and management during and after the pandemic, including prioritization of labor force health and safety.     

Current condition and future directions for lean construction in highways projects: A small and medium-sized enterprises (SMEs) perspective

The aim of this study is to identify the parameters defining how Lean Construction (LC) is being implemented (current condition) and how LC can be further promoted (future direction) from a Small-Medium Sized Enterprises (SMEs) perspective. Although SMEs constitute the largest group in construction supply chains, LC, as an emerging phenomenon in civil construction project management, has been rarely investigated from an SMEs perspective. Also, overlooking the more macro factors like project governance and supply chain management, LC deployments have been mainly discussed from a production process perspective to date. After a review of the extant literature and 20 interviews with managers from the highways sector, a list of 31 current condition and 40 future direction statements were produced, classified under the delivery, process, training, project governance and supply chain related headings and used in a questionnaire survey with 110 responses. The current condition highlights problems like a short-term relations structure, competitive tendering mechanisms, fragmentation, problems in engaging with SMEs for LC, unstandardised LC techniques, and issues with convincing SMEs to deploy LC by demonstrating the business case on mutual benefits. Action items relating to the current project delivery structure were given the highest importance by the supply chain, alongside the LC training and project governance issues for the future of LC at highways SMEs. Additionally, a statistically significant correlation was identified among many future action items.     

用于矿山等极端环境中的高精度定位算法

高精度室内定位技术在矿山、建筑、施工等多种极端环境下都有需求。基于超宽带通信(Ultra Wideband,UWB)的室内定位技术能够提供较高的定位精度,但超宽带信号易受到障碍物的干扰,并且在类似矿山等极端环境中,障碍物不可避免。因此,超宽带非视线传输(Non-Line-of-Sight,NLoS)测距成为当前的一个研究热点。当前研究大多集中在识别和消除非视线传输对超宽带测距的影响上,实际应用中,大多数情形下超宽带信号根本无法穿透障碍物,会导致定位标签只能够与2个或1个信标节点通信,但完成三边定位至少需要3个信标节点。为此,提出了一种基于目标行为分析的定位算法,该算法能够在短时间内仅剩余一个信标节点与标签通信时,也可实现高精度定位。该算法以超宽带通信为基础,使用信号飞行时间(Time of Flight,TOF)算法测距并定位。通过分析信号正常时的目标运动轨迹来判断其速度和方向,当信号不正常时(可通信的信标节点减少),可利用预测的速度和方向参数来实现辅助定位。将该算法部署在一个基于超宽带定位的系统中进行了测试,结果表明:当能够与标签通信并完成TOF算法的信标节点数量少于3个时,基于NLoS传输识别和消除的算法无法完成定位,而基于目标行为分析的定位算法依然能够实现定位,在单信标节点区域的平均定位误差为0.93 m,最大误差为1.41 m,在2个信标节点测距的区域,平均定位误差为0.64 m,最大误差为1.2 m。