Assessing the deformation response of double-track overlapped tunnels using numerical simulation and field monitoring

The unprecedented rate of metro construction has led to a highly complex network of metro lines.Tunnels are being overlapped to an ever-increasing degree.This paper investigates the deformation response of double-track overlapped tunnels in Tianjin,China using finite element analysis(FEA)and field monitoring,considering the attributes of different tunneling forms.With respect to the upper tunneling,the results of the FEA and field monitoring showed that the maximum vertical displacements of the ground surface during the tail passage were 2.06 mm,2.25 mm and 2.39 mm obtained by the FEA,field monitoring and Peck calculation,respectively;the heaves on the vertical displacement curve were observed at 8 m(1.25D,where D is the diameter of the tunnel)away from the center of the tunnel and the curve at both sides was asymmetrical.Furthermore,the crown and bottom produce approximately0.38 mm and 1.26 mm of contraction,respectively.The results of the FEA of the upper and lower sections demonstrated that the tunneling form has an obvious influence on the deformation response of the double-track overlapped tunnel.Compared with the upper tunneling,the lower tunneling exerted significantly less influence on the deformation response,which manifested as a smaller displacement of the strata and deformation of the existing tunnel.The results of this study on overlapped tunnels can provide a reference for similar projects in the future.

Coupler force reduction method for multiple-unit trains using a new hierarchical control system

During traction and braking of multiple-unit trains,substantial longitudinal dynamic forces might occur in couplers due to the non-optimal distribution of traction and braking forces generated by self-propelled carriages.These dynamic forces might create shocks affecting the reduction of endurance of the weakest train structural components primarily.Thus,the overall operational safety of the train is also lowered.The purpose of the paper is to develop a new control system to supervise the activities related to the longitudinal dynamics of each train carriage in a multiple-unit train to reduce the longitudinal coupler forces acting during train traction and braking.The hierarchical structure of the control system consists of two levels.The first master level of control works like standard cruise control.However,the reduction of longitudinal coupler forces is achieved by applying a second level of slave control systems with a control configuration of feedback compensation.

Lateral damage mechanism of the double-track tunnel in the mountainous layered soft rock and NPR anchor cable control

Due to complex geological formations,lateral damage often occurs during excavation in mountainous layered soft rock double-track tunnels.This paper discusses the stresses and the damage characteristics of the surrounding rock under overload in a mountainous layered soft rock double-track tunnel through indoor model experiments to provide a basis for the effective control of lateral damage.The experiments show that the conventional support method cannot effectively control the lateral damage due to interlayer sliding.Therefore,the negative Poisson’s ratio(NPR)anchor/cable control method is proposed.And the scientificity and feasibility of the NPR anchor/cable control technology are proved by the field application and monitoring data of the Minxian Tunnel and Changning Tunnel.It is further demonstrated that high preload is the most effective way to control the lateral damage in layered soft rock tunnels.

The Optimizing Model and Its Solution for Making Train Working Graph with Computer on Separative Division of Double－Track Lines

The authoros specialize in the field of optunization and automatic programme oftrain working graph. In this peper, at frist, a mixed 0-1 integer progranimingmodel about this problem for duuble-track lines is set up, then the principle andProcess of selution are stated, with an application exaiiiple put forward.

Neuronal Activity in the Cerebellum During the Sleep-Wakefulness Transition in Mice

Cerebellar malfunction can lead to sleep disturbance such as excessive daytime sleepiness,suggesting that the cerebellum may be involved in regulating sleep and/or wakefulness.However,understanding the features of cerebellar regulation in sleep and wakefulness states requires a detailed characterization of neuronal activity within this area.By performing multiple-unit recordings in mice,we showed that Purkinje cells(PCs)in the cerebellar cortex exhibited increased firing activity prior to the transition from sleep to wakefulness.Notably,the increased PC activity resulted from the inputs of lowfrequency non-PC units in the cerebellar cortex.Moreover,the increased PC activity was accompanied by decreased activity in neurons of the deep cerebellar nuclei at the nonrapid eye-movement sleep-wakefulness transition.Our results provide in vivo electrophysiological evidence that the cerebellum has the potential to actively regulate the sleep-wakefulness transition.

The Study on Differential Charges of Universities in China

This paper mainly discusses the ＂double-track charge＂ system （ price prejudice charge system ） in theory and practice. The author explains and analyzes the ＂differential charges phenomenon＂ of universities in China by taking ＂Pareto optimality＂ as regulation standard and ＂Darwin optimality＂ as empirical standard, combining regulation standard with practice standard, realistic standard of value judgment with ultimate standard, and fairness with efficiency. This paper provides theoretical reference and an operation platform for application and implementation differential charges and the containment of corruption in college enrollment.