The evolution of a Late Cretaceous–Cenozoic intraplate basin (Duaringa Basin), eastern Australia: evidence for the negative inversion of a pre-existing fold–thrust belt

International Journal of Earth Sciences - The Duaringa Basin in eastern Australia is a Late Cretaceous?–early Cenozoic sedimentary basin that developed simultaneously with the opening of the...     

Correlation between geological units and mineralized zones using fractal modeling in Zarshuran gold deposit (NW Iran)

In this study, the relation between ore grade and geological characteristic has been studied as a principle and also important conceptual in Zarshuran gold deposit in NW Iran. The main subject in this study was identifying a correlation among the ore grade populations and rock types which could be used in other steps of local estimation in the deposit concentration–number (C–N) fractal model and logratio matrix. The C–N log–log plot reveals six geochemical zones defined by Au?<?0.02 ppm as non-mineralized zone and Au?>?0.02 ppm as mineralized zones. According to geological logging and field geology inspection, black gauge, jasperoid, fault gauge and breccia, and carbonaceous rocks are considered as main rock types which contain major Au mineralized zones. The correlation between geological and fractal modeling by logratio matrix shows that there is a good correlation between geological assumed host rocks and C–N fractal modeling. Black gauge rock type with 93.48 % of overall accuracy shows a significant correlation with supergene zone of fractal model, and jasperoid with 92.5 % and carbonaceous rock type with 52.90 % have a decent correlation with highly and lowly mineralized zone of fractal model relatively. Black gauge, jasperoid, and fault gauge and breccia have an approximately near cooperation in this zone for mineralization.     

Self-repair of cracks and defects in clay: a review of evidence,mechanisms, theories and nomenclature

Clay minerals and clayey soils have been extensively researched over the last century leading to a rich and still evolving corpus of knowledge on clay chemistry, microstructure and macroscopic behaviour. Clay has the ability, under certain conditions, to spontaneously repair its cracks. However, despite ample evidence, clay self-repair remains understudied and under-theorised. For example, the majority of experimental studies discussing clay self-repair infer its existence from changes to macroscopic properties assumed to be caused by self-repair, and only a small number of studies have attempted to observe self-repair directly. This paper reviews the literature on clay self-repair. First, it situates clay self-repair within the broader context of self-repairing material. Next, autogenous self-repair of clay, under wet-dry cycles, freeze–thaw cycles and deep-ground consolidation, is presented focusing on evidence, driving mechanisms and key variables of influence. Next, theories of clay self-repair proposed in the literature are discussed, highlighting their scope and limitations, as well as the extent to which they have been validated by experimental observations. Key gaps in current knowledge of clay self-repair are highlighted and ways in which they can be addressed in future research are proposed. Finally, a nomenclature distinguishing between different kinds of clay self-repair is proposed based on eight different attributes.

     

Comparative study of flash flood in ungauged watershed with special emphasizing on rough set theory for handling the missing hydrological values

Natural Hazards - Prediction of the flash floods in ungauged or poorly gauging watershed is one of the challenging tasks in the field of hydrology and needs implication of advanced techniques to...     

Evaluation of the Instability Risk of the Dam Slopes Simulated with Monte Carlo method (Case Study: Alborz Dam)

Embankment dams are one of the most important geotechnical structures that their failures can lead to disastrous damages. One of the main causes of dam failure is its slope instability. Slope Stability analysis has traditionally been performed using the deterministic approaches. These approaches show the safety of slope only with factor of safety that this factor cannot take into account the uncertainty in soil parameters. Hence, to investigate the impact of uncertainties in soil parameters on slope stability, probabilistic analysis by Monte Carlo Simulation (MCS) method was used in this research. MCS method is a computational algorithm that uses random sampling to compute the results. This method studies the probability of slope failure using the distribution function of soil parameters. Stability analysis of upstream and downstream slopes of Alborz dam in all different design modes was done in both static and quasi-static condition. Probability of failure and reliability index were investigated for critical failure surfaces. Based on the reliability index obtained in different conditions, it can be said that the downstream and upstream slope of the Alborz dam is stable. The results show that although the factor of safety for upstream slope in the state of earthquake loading was enough, but the results derived from probabilistic analysis indicate that the factor of safety is not adequate. Also the upstream slope of the Alborz dam is unstable under high and uncontrolled explosions conditions in steady seepage from different levels under quasi-static terms.

     

Discussion of “The effect of energy concentration of earthquake ground motions on the nonlinear response of RC structures” by H. Cao,M.I. Friswell

This discussion raises a few comments and questions on the paper by Cao and Friswell [Cao H, Friswell MI. The effect of energy concentration of earthquake ground motions on the nonlinear response of RC structures. Soil Dyn Earthquake Eng 2009; 29: 292–9.]. The authors consider an interesting problem on seismic response analysis of nonlinear structures. Specifically, the study examines the implication of the energy concentration of the adopted ground acceleration record on the nonlinear response of reinforced concrete structures. The paper employs the wavelet transform to characterize the energy content of the ground acceleration in time and frequency domains.     

Assessing the seismic behavior of steel moment frames equipped by elliptical brace through incremental dynamic analysis (IDA)

Incremental dynamic analysis and nonlinear static pushover analysis are carried out on a performance-based design to determine the seismic demands and capacities of an elliptic braced moment resisting frame (ELBRF). The objective is to assess ductility, overstrength and response modification factors in a modern steel-braced structural system based on incremental dynamic analysis. This integrated system is connected to a beam and column with an appropriate length while providing enough architectural space to allow for an opening without having the common problems associated with architectural spaces in braced systems. Several different classes of buildings are considered on soil type II. Linear dynamic analysis, nonlinear static pushover analysis and incremental nonlinear dynamic analysis related to 12 records from past earthquakes are carried out using OpenSees software. The factors of ductility, overstrength and response modification are calculated for this system. The values of 9.5 and 6.5 are found and suggested only for the response modification factor for ELBRF systems in allowable stress and ultimate limit state methods, respectively. The fragility curves are plotted for the first time for this type of bracing, which contributes to the assessment of building seismic damage.