Besides higher safety standard and less tolerable differential settlement, the approach of foundation design for railway infrastructure shares the same principle as for highway and high-rise building. As such, the key of geotechnical engineering work for railway construction is to identify the geotechnical hazards along the route and generate proper engineering solutions to mitigate or minimize the risk. Considering the characteristics of the geological conditions in the west alluvial plain of Taiwan, soil instability induced by earthquake will be the major geotechnical concern. This paper starts with review of railway damages occurred in 20 earthquakes with magnitude higher than 6 in Richter scale to understand the causes and patterns of railway damage during earthquake. The conclusion is ground movement caused by liquefaction and fault offset is the main reason resulting in railway damage and it is likely to happen in the west alluvial plain of Taiwan. At end, this paper uses a case to analyze ground instability caused by liquefaction and to evaluate the effectiveness of mitigation measures.
The ground vibrations induced by high-speed train have drawn engineer’s interest in recent years. The engineers need to study the vibration characteristics, which include frequency contents and vibration level, to find the vibration mitigation measures. This paper introduces the characteristics of ground vibrations induced by four high speed train systems, and reviews many approaches that have been suggested to be used for ground vibration mitigations. The effectiveness and applications of these vibration reduction methods are also discussed.
This paper introduces the geotechnical conditions and describes the potential problems for mass rapid transit system in Kaohsiung metropolitan. The problems may include the effect of adjacent building, liquefaction, salt pollution, …and other ten kinds. Proceeded the modern construction methods are introduced. The privatized infrastructure is used in this project. The constrained of conventions included design and construction will not so strong. Introducing the modern construction method, using the core of the construction method, and thinking structure of problem solving may stimulate the inspiration of innovation. Stimulating the inspiration of innovation to upgrade the efficiency and safety in the engineering; using the resources more efficiently, smoothly, and rapidly to construct the MRT in Kaohsiung are the characteristics of this project and the final propose of this paper.
Subgrade soil, an essential factor in the road design, is often used to determine the thickness of the pavement. Since, it is involved in a series of soil strength tests, the manipulation of weak soil is required to deal with a suitable method basing on the field situation. Thus, this article aims to introduce the functions, the methods and the development of the tests for subgrade. In addition, the solutions to insufficient bearing capacity in weak soil subgrade are also introduced, such as increasing soil capacity by soil reinforcement, and decreasing loading by lightweight soil. Moreover, the case studies on the lightweight of EPS embankment and reinforced earth are also presented in this paper.
Effects of reinforcement and soil nailing to the seismic stability of soil retaining walls are investigated based on the results of a series of shaking table tests on model retaining walls. A new psuedo-static method for analyzing the displacements of soil embankments and retaing walls are developed. The method for displacement analysis developed in this study provides accurate results, and is proved to be an effective tool for evaluating possible damages of highway embankments and soil retaing walls induced by major earthquakes.
In the arena of pavement management, GIS pavement network maintenance management is one kind of information system. Not only does it play the role of transaction (e.g. records of pavement condition changes, records of work construction and so forth) but also the supportive role of policy-making (e.g. the prioritized order of pavement maintenance). However, with the formidable omnipresence of Internet, the traditional pattern of pavement network maintenance management has to be gradually transformed. With the transformation, the information of pavement network maintenance would be boundless, and analyzed application situation would be publicized on Internet since correct information could be transmitted immediately. Therefore, a function pattern like this would require a boundless work process management system ensuring previous strong function, and a system established via Internet/Intranet would perfectly meet this demand. This paper was written to address the issue of GIS pavement network maintenance management.
How to choose a suitable structural type is designed regarding a highway crossed by a railway? One way is adopting overpass, the other one is under through. When construction of latter is carried out, smooth of operation and safety of transport must be ensured. For these reasons, besides full care of design and management of construction must be given close attention, a full coordination with the related unit of Taiwan Railway Bureau is crucially important. This article is mainly about using open cut and underpinning method to solve this engineering problem. There is a complete collection of information regarding design and construction of this method, points to pay attention regarding interface coordination and attentive matter of design between designer and Railway Bureau and a complete design case. The objective of this presentation is to provide reference to all who are concerned when similar designs are encountered in the future.
In 1994, during the construction of the Nankang Line, Taipei MRT, a unique event of water ingress was accidentally encountered at the Westgate Station Site of contract CN252. The Contractor with the intention to replace a faulty piezometer drilled a hole down to a depth of 20.5 m from the bottom of a 24.5 m deep excavation site induced large amount of water outflow with running sand, causing cracks and settlement on the adjacent Chung Hwa Road, and movement on the retaining system. To save the site from the verge of collapse, emergency measures such as gravel backfill, water filling, ground improvement by cement grouting, additional struts and seal-off grouting etc. were applied timely at various stage of remedy. This Paper which consists of two parts describes the complete history of the water ingress event. Part 1 as reported herein covers its occurrence, ground condition assessment, emergency actions and their considerations. Instrumentation data are presented to show the responses of ground movement. Finally a review comment on the measures used is given. The design and construction processes of the seal-off grouting prior to work resume will be reported and discussed in Part 2, in an accompanied Paper.
This Article is the Part 2 of the previous Paper on the water ingress event occurred at the CN252 site. The site which was temporarily stable after the emergency measures under-taken, still required complete sealing off of all water paths, drilled holes and soil strengthening below the excavation grade prior to work resume. Described in details herein, are the design considerations and grouting processes used; it covers the objectives and zoning of grouting, grout holes layout, grout depth of each zone, mixture of grouts, grouting pressure specified and sequence of work. To overcome the upheaval of king posts and struts due to injection of grout into the confined area, many modifications on grouting processes have been applied. Finally, laboratory tests results of drilled samples and still water tests in the grouted area proved that the grouting work is effective. The concluding remarks emphasize the invaluable experience achieved from the grouting work and the lessons learned from this event. The necessity of placing more weight onto the role of geotechnical engineers in deep excavation projects are also stressed.
KEY WORDS：grouting with standpipes, tube-a’-manchette grouting technique, low pressure grouting, cement-bentonite mixture, cut-off wall, LW (labile waserglas) grout method, ground upheaval, soil improvement, still water test.