Investigation into the effect of uncertainty of CPT-based soil type estimation on the accuracy of CPT-based pile bearing capacity analysis

Cone Penetration Test (CPT or CPTu) is commonly used for estimating soil types and also for the geotechnical design of pile foundation. However, the level of agreement between the CPT-based soil types and the traditional identification of soil types based on samples may vary significantly; and it is not clearly understood if this variation has any sort of relationship with the CPT-based pile design. To investigate into this area, a ground investigation trial was carried out at six different locations as part of a highway scheme in East of England. At each location the trial comprised one CPTu adjacent to one borehole (BH) with conventional sampling and laboratory testing. The soil types were estimated from the CPTs and compared with the boreholes findings, and the levels of correlation between them were established. Similarly, the ultimate bearing capacity of a typical bored pile based on the CPTs and on the BHs were calculated and compared. Despite the variable level of disagreement of the CPT-based soil type estimation with the BHs findings, the pile capacity based on CPT data was found to be generally consistent with the values obtained from the traditional BHs-based pile design

Sustainable geotechnics

"Sustainable Geotechnics" may be considered as a discipline in ground engineering, appearing recently in the construction industry in response to the emerging Low Carbon Economy concerning the global challenges of climate change, diminishing fossil fuel reserves, and environmental management. In the UK Low Carbon Economy is often considered in terms of 'decarbonisation' of buildings, transport, industry, and power sector. This is to be addressed using a wide variety of sustainable approaches, which produce great challenges and opportunities to ground engineers. This paper discusses how the emerging Low Carbon Economy will affect the design and construction of low-carbon buildings and infrastructure as well as innovation covering some of the sustainable approaches recognized by ground engineering communities

Towards Efficient Computation in Real-Time Systems

Graph algorithms have gained popularity and are utilized in high performance and mobile computing paradigms. Input dependence due to input graph changes leads to performance variations in such algorithms. The impact of input dependence for graph algorithms is not well studied in the context of approximate computing. This thesis conducts such analysis by applying loop perforation, which is a general approximation mechanism that transforms the program loops to drop a subset of their total iterations. The analysis identifies the need to adapt the inner and outer loop perforation as a function of input graph characteristics, such as the density or size of the graph. A predictive model is proposed to learn the near-optimal loop perforation rates using synthetic input graphs. When the input-aware loop perforation model is applied to real world graphs, the evaluated graph algorithms systematically degrade accuracy to achieve performance and power benefits. Results show ~30% performance and ~19% power utilization improvements on average at a program accuracy loss threshold of 10% for an NVidia GPU. The analysis is also conducted for two concurrent Intel CPU architectures, an 8-core Xeon and a 61-core Xeon Phi machine

Laboratory measurement of time-dependent deformation properties of muddy siltstone.

This paper investigates the time-dependent deformation of argillaceous rocks, drawing principally on laboratory experiments carried out on muddy siltstone recovered from an open pit mine located in the midlands, UK. A series of creep tests were conducted on both intact and fractured rock samples to cover the two ultimate structural conditions of rock mass. Based on the creep test results, the relationship between axial strain and time under different axial and deviatoric stresses was investigated. The creep data of both intact and fractured rock samples was successfully fitted to Burgers model to represent creep behaviours of pre and post failure. The study provides improved representation of the time-dependent deformation properties of rock mass, which is essential to enhance geomechanical modelling of long-term stability of abandoned mines and for the application of underground disposal of radioactive waste.Research Programme of the Research Fund for Coal and Steel (RFCS), grant numbers RFCR‐CT‐2003‐00011