上软下硬地层大直径土压平衡盾构下穿民房建筑群沉降控制北大核心CSCD

依托广州地铁18号线盾构施工,针对其地层分布复杂、软硬差异大及穿越密集民房建筑群等特点,通过注浆加固、现场动态监测、优化掘进参数等一系列主动措施,解决实际工程中掘进参数合理取值与地表建筑沉降变形控制两大难题。研究结果表明:(1)在该类软硬地层中掘进时,刀盘在通过不同岩层断面分界线时扭矩、推力等参数波动较大,总推力与扭矩有良好的相关性,各掘进参数宜控制为:推力30000~35000 kN、扭矩4500~6000 kN·m、推进速度35~45 mm/min;(2)提出的多段式封孔洞内超前注浆工艺可使刀盘前18 m范围内的地表上抬3~5 mm,最大上抬值能达9.02 mm,同时能缓解土体在盾构下穿时及后续固结稳定的沉降趋势;(3)因刀具磨损、掘进参数波动大、螺旋机卡死等引起的临时停机会造成地表建筑日沉降速率超过3 mm/d,在预设停机点位置前采取洞内超前注浆和克泥效工法能有效缓解沉降趋势,在带压开舱期间日沉降速率控制在2 mm/d以下;(4)左右隧道轴线附近的地表建筑沉降基本可分为“微小隆起—沉降较大—逐渐稳定”三个阶段,测点最大沉降值最终稳定在-21.38 mm、-22.49 mm,均小于控制值。     

Study on Mechanical Properties of Tunnel Lining Structure with Spray-applied Waterproofing Membrane北大核心CSCD

In order to study the influence of spray-applied waterproofing membrane layer on the mechanical properties of tunnel lining structure, a numerical calculation model of composite lining, spray-applied waterproofing lining and single-shell lining is established according to the mechanical parameters and interface parameters of waterproofing membrane measured by tests, and comparative analysis is made on the mechanical properties of the three types of lining structures. The research results show that: (1) compared with the composite lining, the stress of the secondary lining in the spray-applied waterproofing lining structure is significantly reduced, and the stress of the initial support has little change, but the displacement of both the initial support and the secondary lining increases; (2) in the spray-applied waterproofing lining structure, the whole section of the secondary lining is in the state of small eccentric compression, and the safety factor is greatly improved; (3) spray-applied waterproofing membrane layer can improve the cooperative force-bearing capacity of initial support and secondary lining, and improve the stress state of secondary lining, which is beneficial to improve the safety of secondary lining; and (4) with the increase of the cooperative force-bearing capacity of spray-applied waterproofing lining structure, the internal force of spray-applied waterproofing lining structure will be infinitely close to that of single-shell lining structure. © 2022, Editorial Office of Modern Tunnelling Technology. All right reserved.     

临近端头井盾构开挖引起土体沉降数值分析北大核心CSCD

文章以南昌地铁2号线雅苑路站施工为例,基于小应变硬化土体(HSS)本构模型,建立从端头井始发的双线盾构隧道掘进模型,分析了基坑开挖与双线盾构掘进共同作用下的土体沉降规律。结果表明:(1)加固盾构始发区土体可有效减弱区域范围内地表沉降,该区域内地表沉降量远小于区间隧道沉降量;(2)在同一埋深条件下,先建隧道地表沉降最大值高于后建隧道地表沉降最大值,地表横向沉降槽呈现非对称W型;(3)基坑开挖与盾构掘进共同作用下引起的地表沉降值,可以由二者单独作用产生的沉降值叠加计算得到。     

Collecting longitudinal data from freight operators: survey design and implementation ideas and challenges

Freight transport research has generally been limited by a lack of data of the breadth and quality available for passenger transport, particularly in terms of behavioural data. This paper discusses the survey design and implementation of a survey intended to collect longitudinal behavioural data on the responses of freight transport firms to environmental policies. The design of the survey is centred around a hypothetical scenario where respondents are asked how they would complete a given freight task within common constraints. One of the key components of the survey design is a dynamic component intended to simulate the changing business environment. The paper illustrates the many challenges in getting complex freight related surveys in the field.     

An economic model for sustainable harbor trucking

Truck emissions at a port may have a severe impact on neighbors, resulting in a politically sensitive sustainability issue for the port management. Strict emissions controls may adversely affect throughput whereas the lack of strict controls will be unacceptable to local citizens and environmental interests. We develop an economic model minimizing cost of truck emissions control and collateral production changes and apply it to decision making for a port seeking to meet a throughput goal while also attempting to satisfy an emissions constraint. Outcomes predicted by the model allow informed decisions about the impact of controls.     

The drinking driver: a medical view

Accidents are the third main cause of death in Europe with 40% of them due to road traffic accidents (RTAs). These victims are mainly young male drivers/riders and elderly pedestrians. One quarter of the deaths and 10% of the injuries are associated with alcohol. Consumption of alcohol is generally increasing. Ignorance of the effects of alcohol on the body and on the performance of skilled mental and physical tasks contributes to the number of road users who are impaired by alcohol. Alcohol is a depressant drug which impairs information processing in the brain. The risk of being involved in a RTA increases very rapidly with increasing concentration of alcohol in the body. There are probably two groups of drivers, the majority who do not drink, or who drink very little, before driving and those who regularly drink whether or not they are going to drive. The former (the social drinker) can do without his drink, the latter (the problem drinker) cannot. Various legislative measures have been introduced in different countries with varying success. Most developed countries now make it illegal to drive with more than a stipulated concentration of alcohol in the body. Much discussion centres round what further legal steps should be taken to reduce drinking and driving, especially the more widespread use of random roadside breath testing of drivers. Doctors are much concerned in this public health problem which causes such misery and waste of resources and are involved in research on the physical and psychological effects of alcohol, the best methods of educating drivers on these effects and, where necessary, identifying those who are misusing alcohol to the extent that they should be kept off the road.     

Optimal assignment for check-in counters based on passenger arrival behaviour at an airport

Establishing how to utilize check-in counters at airport passenger terminals efficiently is a major concern facing airport operators and airlines. Inadequate terminal capacity and the inefficient utilization of facilities such as check-in counters are major factors causing congestion and delays at airport passenger terminals. However, such delays and congestion can be reduced by increasing the efficiency of check-in counter operations, based on an understanding of passengers' airport access behaviour. This paper presents an assignment model for check-in counter operations, based on passengers' airport arrival patterns. In setting up the model, passenger surveys are used to determine when passengers arrive at the airport terminals relative to their flight departure times. The model then uses passenger arrival distribution patterns to calculate the most appropriate number of check-in counters and the duration of time that each counter should be operated. This assignment model has been applied at the Seoul Gimpo International Airport in Korea. The model provides not only a practical system for the efficient operations of time-to-time check-in counter assignments, but also a valuable means of developing effective longer-term solutions to the problem of passenger terminal congestion and delays. It also offers airlines a means of operating check-in counters with greater cost effectiveness, thus leading to enhanced customer service.