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[Display omitted] Establishing a suitable tunnel boring machine (TBM) performance estimation model is benefit to the machine type selection, project scheduling and budgeting. Although various models have been developed to predict TBM performance, most of these models use a relatively small specific database, which is difficult to be applied to engineering practice. In this study, some equations for estimating TBM penetration rate (PR) applicable to different geological conditions are proposed. Firstly, a TBM construction performance database containing 159 tunnel sections is built according to four different tunnel projects originating from China, which covers rock mass properties, TBM specification parameters and performance information. By eliminating the effects of some TBM specification and operating parameters, a normalized energy index is proposed for assessing the rock mass boreability. On this basis, a series of statistical analysis, i.e. linear multiple regression (LMR) and non-linear multiple regression (NLMR) are used to develop some empirical equations for estimating the PR by employing rock mass properties and TBM specification parameters, and more than 84% of the PR can be accurately predicted. Finally, to further evaluate the prediction performance of these equations, they are compared and discussed with fifteen published typical models, and the results proved that the models developed in this study are more reasonable and reliable. It should be noted that the input parameters of these equations are readily available at the project planning stage, thus they are very simple and practical for designers and constructors. [ABSTRACT FROM AUTHOR]

Abstract: Landscape design of tunnel portals has been under intensive study in recent years. This paper summarizes the general development of highway tunnels and the main problems concerning highway tunnel entrances during this development phase in China. It then analyzes the significance of mountain highway tunnel landscape design in terms of preventing travel fatigue, visual adaptation, communicating and displaying culture, land marking, and environmental protection. Thirdly, it lays down the principles for landscape design, e.g. safety, failure prevention, physiological, anthropological, blending and economic principles. Lastly, it discusses the diversity of landscape designs in China, including types of tunnel portals, integration with local cultures (subdivided into ethnological culture, regional culture and historical culture), environmental protection awareness, lighting transitions in tunnel entrances, blending with the surrounding environment, symbolic and metaphorical skills in tunnel portal landscape design, and special decorations. The results suggest that landscape design of tunnel portals is a comprehensive artistic endeavor, involving local culture; bionomics; psychology; environment protection; lighting; structural techniques; new material implementation; and new technical arts. In conclusion, good landscape design requires intensive and collaborative interdisciplinary studies. [Copyright &y& Elsevier]