Generally tunnelling in urban ground condition is not always favourable due to the tunnels’ susceptibility to major displacement especially when excavated in the soft soil and/or weak weathered rock formation. Apart from conventional support systems, pre-support measure like forepoling umbrella arch is frequently used to reinforce the ground. Modern computational tools allows the inclusion of multi-stage excavations and pre-support which was not possible in two dimensional (2D) plane strain. This paper demonstrates the three dimensional (3D) finite element analysis of Pahang-Selangor raw water transfer tunnel, as a reference case, where multi-stage excavation and pre-support are incorporated as intrinsic part of the model. The New Austrian Tunnelling Method (NATM)-3 segments which encountered Grade III weathered granite, having shallow overburden cover, was selected for numerical analysis using RS3 software. Comparison between simulated and observed data has shown good agreement during verification

Road cutting, open pit mining, quarrying and various other constructions in hilly terrain demand special attention in terms of slope stability. The analysis of slope stability is of great significance not only for ensuring safe design of excavated slope, but also for preventing potential hazards. This research was undertaken to identify the controlling parameters affecting the slope instability. As the rock slope behaviour is mostly governed by discontinuities, discontinuum numerical technique such as Discrete Element Method (DEM) which has the ability to address discontinuity controlled instability is well suited for this case. This study investigated the failure pattern and its responsible factors leading to failure of a slope at a slate quarry situated in Wales, United Kingdom as a case study. The research work consisted of field investigation, laboratory experiments and parametric analysis by powerful and renowned distinct element computational tool Universal Discrete Element Code (UDEC). Evidence showed that complex failure mechanism involving distinct planar sliding surface along with block-flexural toppling contributed to the instability at the studied slate quarry. Dip of discontinuity, presence of water, weathering state and slope angle were the significant factors found in this study to have profound impact on controlling rock slope instability. The modelling results also indicated that the influence of structurally dipping at 78° of cleavage in slate and the water filling in the crack which developed excess water pressure have triggered the failure.