Geotechnical Engineering Online Library

The faults and fractures are known as two of the most important parameters in earthquake occurrence. During the construction in urban areas, faults and fractures may be covered in depth and thus are not visible at the ground surface. In this context, non-invasive geophysical prospecting methods (microtremor and geoelectrical methods) and borehole data were used to detect subsurface geological structures hidden faults) in a suburb of Shirz in Iran. The horizontal to vertical spectral ratio HVSR) method was used to obtain the dynamic parameters (predominant frequency and resonance amplitude) f the soil, to detect hidden faults. The results show that the abrupt changes in the sediment thickness and predominant frequencies at a specific direction (NW-SE) can be related to the displacement of a nearly vertical fault with NW-SE trend. In addition, the electrical resistivity method using continuous resistivity profiling (CRP) and Schlumberger arrays was employed to detect a hidden fault and the results were compared with previous data. The obtained results of both arrays illustrate the presence of a nearly vertical fault with NW-SE trend in the region. Comparison of all results shows that the detected faults by both methods are consistent with each other. Therefore, it can be conclusive that combination of the two methods is a useful and reliable approach to study and detect hidden faults.

Thermo-active diaphragm walls have proved their effectiveness in the thermal conditioning of buildings and infrastructures. However, some aspects still need to be investigated in order to tailor methods and tools for an accurate prediction of their energy and structural performance. In this perspective, some issues are addressed that concern the definition of models for the numerical analysis, in particular issues about the modelling of geometry and thermal boundary conditions. Taking advantage of a monitoring programme on a real full-scale structure, this research focuses on the assessment of heat transfer process and thermal response of diaphragm wall and soil mass on the basis of field data. Understanding of the heat transfer process contributes to the definition of the time-dependent thermal boundary conditions at the excavation side. From the analysis of thermal gradients in the wall, the condition at the excavation side is recognised as a major factor that influences the heat transfer process, governing the direction of the heat flux in different seasons of operation of the geothermal system.