Showing papers by "Mott MacDonald published in 1995"

Real-Time Water Allocation for Irrigation

Abstract: Throughout the world the importance of water management is becoming more important as the demand for water increases. As one of the major uses of water, irrigation could benefit from improved management practices. The establishment of a Water Operations Centre in Indonesia has seen the development of a real-time water-allocation model for a complex irrigation system covering 60 000 ha. The model uses linear programming (an optimization technique) to determine the best way in which to allocate limited water supplies while keeping crop yield losses to a minimum.

Role of engineering geology in natm construction

Abstract: The basic design philosophy of the New Austrian Tunnelling Method (NATM) of construction is implicitly reactive; it has been referred to as an observational method as monitoring is required to allow the optimization of support and to ensure that deformations are maintained within the definitions of safety. Benefits are obtained by optimizing the timing and nature of the primary ground support to suit the conditions exposed based on observations of performance during incremental construction. Engineering geologists have a pivotal role in investigating ground conditions and assessing the key design parameters in design modelling, monitoring and in observing the changing ground conditions during construction. Engineering geologists are also involved in decision-making processes for altering support types based on feedback from performance monitoring. Four major projects are discussed where multiple heading and incremental excavation and sequential support techniques have been implemented, which required the skill of engineering geologists and rock mechanics engineers. There is a need for a systematic appraisal of ground conditions and for further documented case studies. There are many opportunities for engineering geologists in this interdisciplinary, interactive, observational design and construction process.

Rock engineering for dundee inner ring road

Abstract: Stage XII of Dundee Inner Ring Road runs through a built-up part of the city of Dundee and includes a 145 m long cut and cover tunnel and a 355 m length of road in vertical open cut with retaining walls. Excavations extended 14 m below the level of adjacent ground. During construction, disturbance to nearby buildings and services had to be minimized; close attention was paid to the stability of the excavations and the selection of excavation techniques. This paper presents an outline of the site geology, describes the approach to geotechnical investigations and highlights certain aspects of design and construction, particularly the stabilization of the sidewalls and the role of detailed geotechnical mapping. The route runs within a Devonian age sandstone-mudstone-shale-basic lava sequence dipping at 20 to 30 degrees. Historically, stability problems have occurred in these formations in the Dundee area. Site investigations included inclined coring to clarify the disposition of faults, exploratory trenching, cross-hole seismic surveys and rock anchor trials. Particular attention was paid to elucidating the discontinuity characteristics with reference to the presence of low shear strength planes. Rock classification techniques were used to assist in excavatibility studies and to provide guidelines for rock reinforcement selection. Excavations were mapped in detail during construction, and supplementary rock testing was carried out. Updated interpretations were prepared, enabling the design for the temporary and permanent works to be kept under review and adjusted as work progressed.

Structural simulation using numerical analysis

Abstract: Publisher Summary The power of present-day computers in conjunction with increasingly sophisticated numerical analysis programs provides engineers the analysis capabilities These capabilities encompass fluid and structural mechanics and incorporate the whole range of nonlinear phenomena However, the very power and universality of the capabilities brings a growing necessity to ensure they are applied in a correct and valid manner Mistakes could be very costly and difficult to detect during the analysis process This chapter presents examples of the application in structural mechanics of the finite element method applied in a nonlinear manner to the prediction of the ultimate loads for various types of structures The lessons learned in preparing the numerical models and interpreting the results from the computer programs are described in the chapter The chapter concludes with a discussion on the implications for engineering practice and education of the increasing availability and application of computer based numerical analysis programs It is concluded that there will be a trend to greater application of numerical analysis to simulate the complete history and behavior of engineering systems, but that the technical capabilities of the engineers involved in this work must be at the highest level and organized in such a manner as to ensure physical validity of the results