Rock fragmentation is frequently observed during rockfalls events , but it is rarely considered in rockfall analysis and rockfall protection system design because it is a complex phenomenon, influenced by many factors that are not very well understood. Only limited experimental and numerical studies exist on fragmentation and the current status of knowledge about fragmentation does not allow it to be modelled in a predictive manner. The presentation will focus on an extensive fragmentation testing campaign conducted to obtain high quality fragmentation data that addresses this knowledge gap and provides a foundation for future fragmentation research. The campaign was conducted by using artificial rock blocks on specifically-designed apparatus built to study quantitatively the complex phenomenon of fragmentation of rocks upon impact. Multiple high-s peed cameras are used to capture and reconstruct the impact and 3D trajectories of flying fragments. A significant contribution of this research to rockfall engineering was the development and validation of a novel model that can reliably predict the impact survival probability of brittle homogenous spheres and irregular rocks under collinear impact, using data from standard quasistatic UCS and indirect tensile laboratory tests , with the potential for extension to irregular shapes and natural rock materials.

Energy Connect, a new 700km 330/500kV transmission line, will be the longest new transmission line project constructed in Australia in recent times. Linear infrastructure projects face many challenges in their planning and delivery due to significant changes and variability in geological, environmental, climatic and stakeholder inputs. Comparable infrastructure projects in terms of linear extent, such as the Pacific Highway Upgrade, have typically been delivered in multiple stages, however Energy Connect is being delivered in its entirety in one package.

This presentation provides an insight into the delivery of the geotechnical investigations for the project that to date, have included over 800 boreholes, 1200 Cone Penetration Tests and 400 Electrical Resistivity Tests. This presentation will present an overview of some of the logistical challenges faced when conducting geotechnical investigations over such a vast linear distance and will also discuss the wide range of investigation techniques undertaken.

The project spans from Wagga Wagga in NSW to the South Australia/NSW border, north west of Buronga. The project has been divided into four main overhead transmission line components ranging in length from 30km to approximately 400km, across largely rural and remote parts of New South Wales. Critical to the successful delivery of the investigations has been the detailed planning and methodical execution of the investigations. Local community engagement has been paramount to the successful delivery of the investigations, with many local business suppliers becoming positively engaged with this significant energy infrastructure project.
Appropriate equipment selection, careful selection of competent and experienced subcontractors and management of materials, fuel, samples and waste were all taken into consideration in the planning and execution of the investigations, that have taken place over 2.5 years.

To ensure consistent and high quality investigation data was obtained, SMEC utilised an inhouse, digital logging platform. The implementation of this digital logging platform had many tangible benefits to the project that will be presented.

The redevelopment of Sydney’s Central Business District has prompted a trend toward updating the existing heritage buildings to include modern functionality while preserving their historical integrity. The Lands Department Sandstone project involves transforming the Lands Department’s heritage sandstone building into a modern luxury hotel, requiring excavation within the building footprint to deepen its basement by two levels for the construction of lifts, back-of-house and service areas, and a tunnel.

The project geotechnical challenges included numerous rock joints due to proximity to the G.P.O. Fault Zone.  The jointing results in rock wedges and other mechanisms that required underpinning of the heritage and new foundations adjacent to the new excavation.  Limited ground deformation tolerance of heritage buildings and restricted machinery access exacerbated the design and construction complexities.  Site investigation demonstrated the variable geotechnical conditions, with downhole camera inspections implemented to confirm the rock jointing locations with precision for the underpinning design.

A precast concrete beam with steel members, acting as a wall “transfer” structure, was designed and constructed to transfer the loads from an existing 5-storey sandstone block wall, which was located directly over the proposed shaft excavation, onto new underpinned foundations on both sides of the excavation.  The underpinning of the new transfer beam and the other existing footings alongside the proposed shaft excavation was designed to be supported by rock bolts.  To address building settlement risks, flat jacks were incorporated into the transfer structure foundations and an optimisation of the excavation geometry and construction sequence was implemented, accompanied by design verification through trial trenches and staged excavation.

Through innovative engineering solutions, and meticulous planning construction and verification, this project successfully solved the geotechnical complexities associated with the redevelopment of the heritage building while preserving its historical integrity, and provided a valuable precedent for future development.

Three-dimensional (3D) cellular inclusions such as geocells and scrap rubber tyres improve the engineering properties of the infill materials by providing all-around confinement. Although the 3D geoinclusions possess immense potential in the railway industry, their application is still limited due to a lack of adequate techniques to evaluate the magnitude of improvement provided by these artificial inclusions. This study presents an innovative computational approach to evaluate the effectiveness of 3D cellular geoinclusions in improving the performance of ballasted railway tracks. The proposed method is an integrated approach that combines the additional confinement model with the geotechnical rheological model for a railway track. The methodology is applied to an open track-bridge transition, and the results revealed that the geoinclusions substantially reduce the differential settlement. However, the magnitude of improvement depends on the opening size, placement location within the track and material used to manufacture the cellular inclusions. Moreover, the magnitude of settlement reduction also depends on the axle load and subgrade soil properties. The proposed methodology can assist the railway engineers in assessing the efficacy of 3D inclusions in improving the performance of railway tracks and help select the most appropriate material, size, and location of reinforcement for deriving maximum benefits.