RECENT DEVELOPMENTS IN SITE INVESTIGATION AND TESTING FOR HARD ROCK TBM PROJECTS
For several recent TBM tunnel projects, unexpected ground conditions have been encountered, causing extra cost, considerable delay, and in some cases major claims. Undoubtedly, insufficient and/or irrelevant site investigation and testing are among the main causes of such incidents. The purpose of this paper is to review the main investigations and tests relevant for hard rock TBM projects, with particular emphasis on the considerable development that has taken place over the last few years. Also, guidelines for defining optimum scope and extent of site investigations and testing are discussed, as well as the importance of adjusting the investigations and tests according to complexity of the ground conditions and project type.
Improving Performance of Shield TBM for Subway Tunnel Passing Through Riverbed
As a technology of mechanical excavators is developed, an application of Shield TBM becomes variable and wide. As a result, shield TBM can be applied most geological conditions, such as soil condition with high water pressure, hard rock condition, and mixed condition. However, an extensive and detail geological investigation should be conducted to select most suitable equipment and cutting tools for high performance. This paper will focus on an improvement of shield performance in difficult condition by alternative plans and modifications of shield TBM.
Hard rock tunnel boring: Prognosis and costs
Abstract This paper is drawn from four project reports, dealing with: (1) hard rock tunnel boring; (2) drill-and-blast tunnelling—prognosis; (3) drill-and-blast tunnelling—costs; and (4) a drillability and drilling rate index catalogue. The project reports are based on jobsite follow-up work of both bored and blasted tunnels. This paper summarizes some developments in TBM and cutter design, factors influencing the boring process and factors that affecting tunnelling costs, e.g. the increased productivity possible with TBMs.