Sediment physical properties of the DYNAS study area

Physical properties of the deposits in the DYNAS study area, the Mecklenburg Bay, were investigated using sediment echosounders and laboratory analysis were carried out on undisturbed short sediment cores. Wet bulk densities of about 1.2 g/cm³ for mud and up to 1.9 g/cm³ for silty sand were found in surface sediments of the Mecklenburg Bay. Sediment density–depth functions were approximated by logarithmic regression functions at different depth intervals. Sediment consolidation was studied by both (i) consolidation tests of sediment samples and (ii) from the void ratio–overburden pressure relation in natural sediments. Low shear strength values of 9–71 Pa were measured at the mud surface. Downcore, a depth gradient of about 14.5 Pa/cm was calculated. Sediments with high silt and sand contents are characterized by shear strength values of up to 3000 Pa. Published formulas derived from erosion studies were used to calculate the critical shear stress using wet bulk density and shear strength. The obtained results demonstrate clearly, that there is still a wide gap in knowledge about the relationships between erosion parameters and sediment physical properties.     

采用轮缘润滑装置降低轨道磨损

自从有了轨道交通后,轨道的磨损导致巨大的耗费就成了大问题.实践经验表明,轨道并非可无限制使用,磨损到一定程度后就必须更换,否则就会导致列车出轨,严重时会酿成灾难性事故.在蒸汽机车刚开始运行的时代,轨道的磨损就已经很严重了,随着电力机车和内燃机车投入应用,轨道的磨损愈加严重.这是因为相比较蒸汽机车的蒸汽机排放的蒸汽含油,喷出后会有精细油膜沉落到轨道上——虽然这些油膜还不足以解决过度的磨损问题,但磨损状况可有所改观。     

High- Speed railway lines in Germany:Experience in Tunnelling in Karstic Geology and Discussion Of Tunnel Driving Methods

In the course of Deutsche Bahn's new high - speed railway line between Nuremberg and Ingolstadt, a number of tunnels are being constructed, with a total length of about 15 km. One of the longest tunnel is the 7,250 m long Irlahüll tunnel.The tunnel was driven in karst geology. It was not expected that karst phenomena would be so widespread. This forced client, designer and contractor to take a new approach to the project. Different tools were developed to handle the problems on site. Additional site investigations had to be performed to identify karst phenomena in the vicinity of the tunnel. For validating the stability and serviceability of the tunnel, a new way of defining the probability of failure of the construction had to be found. Based on the experience of the tunnel driving at the high - speed railway line in Germany between Nuremberg and Ingolstadt, two different methods of tunnelling are discussed: Drill and blast ( New Austrian Tunnelling Method: NATM) and the use of tunnel boring machines (TBM).     

Disturbance compensation with a torque controllable steering system

Via a conventional steering system the driver perceives desired and disturbing effects such as road feedback and resonance effects, respectively. They appear with overlapping frequency spectra within the driver's steering torque. This paper introduces a control algorithm that is suppressing periodic disturbances without affecting useful steering road feedback attributes as well as regular power assistance characteristic. This is realised by an integrated torque actuator within the steering column in conjunction with a conventional Hydraulic-assisted Power Steering (HPS) system.     

德国高速铁路岩溶隧道工程经验和施工方法

在德国新高速铁路线Nuremberg至Ingolstadt段的工程中,修建了总长约15 km的若干座隧道,最长的是7 250 m的Irlahüu隧道.该隧道是在喀斯特地质条件下开挖的.当时没想到喀斯特地质现象分布范围如此广泛,迫使业主、设计人员和承包商对该工程采取了一些新对策.他们研制了一些不同的机具来应付现场发生的问题.同时不得不增加了一些现场勘查工作以查清隧道附近的喀斯特现象.为确保该隧道的稳定性和服务能力,还必须找到一种新的确定施工事故概率的新方法.根据德国高速铁路Nuremberg至Ingolstadt段的隧道施工经验,本文将对两种隧道施工方法钻爆法(或新奥法)和TBM法进行讨论.