Energy partitioning during seismic slip in pseudotachylyte-bearing faults (Gole Larghe Fault, Adamello, Italy)   总被引：1，自引：0，他引：1  

Lidia Pittarello  Giulio Di Toro  Andrea Bizzarri  Giorgio Pennacchioni  Jafar Hadizadeh  Massimo Cocco 《Earth and Planetary Science Letters》2008,269(1-2):131-139

The determination of the earthquake energy budget remains a challenging issue for Earth scientists, as understanding the partitioning of energy is a key towards the understanding the physics of earthquakes. Here we estimate the partition of the mechanical work density into heat and surface energy (energy required to create new fracture surface) during seismic slip on a location along a fault. Earthquake energy partitioning is determined from field and microstructural analyses of a fault segment decorated by pseudotachylyte (solidified friction-induced melt produced during seismic slip) exhumed from a depth of ~ 10 km—typical for earthquake hypocenters in the continental crust. Frictional heat per unit fault area estimated from the thickness of pseudotachylytes is ~ 27 MJ m^− 2. Surface energy, estimated from microcrack density inside clast (i.e., cracked grains) entrapped in the pseudotachylyte and in the fault wall rock, ranges between 0.10 and 0.85 MJ m^− 2. Our estimates for the studied fault segment suggest that ~ 97–99% of the energy was dissipated as heat during seismic slip. We conclude that at 10 km depth, less than 3% of the total mechanical work density is adsorbed as surface energy on the fault plane during earthquake rupture.  相似文献   

Development of a new connection for precast concrete walls subjected to cyclic loading     

Ramin Vaghei  Farzad Hejazi  Hafez Taheri  Mohd Saleh Jaafar  Farah Nora Aznieta Abdul Aziz 《地震工程与工程振动(英文版)》2017,16(1):97-117

The Industrialized Building System (IBS) was recently introduced to minimize the time and cost of project construction. Accordingly, ensuring the integration of the connection of precast components in IBS structures is an important factor that ensures stability of buildings subjected to dynamic loads from earthquakes, vehicles, and machineries. However, structural engineers still lack knowledge on the proper connection and detailed joints of IBS structure construction. Therefore, this study proposes a special precast concrete wall-to-wall connection system for dynamic loads that resists multidirectional imposed loads and reduces vibration effects (PI2014701723). This system is designed to connect two adjacent precast wall panels by using two steel U-shaped channels (i.e., male and female joints). During casting, each joint is adapted for incorporation into a respective wall panel after considering the following conditions: one side of the steel channel opens into the thickness face of the panel; a U-shaped rubber is implemented between the two channels to dissipate the vibration effect; and bolts and nuts are used to create an extension between the two U-shaped male and female steel channels. The developed finite element model of the precast wall is subjected to cyclic loads to evaluate the performance of the proposed connection during an imposed dynamic load. Connection performance is then compared with conventional connections based on the energy dissipation, stress, deformation, and concrete damage in the plastic range. The proposed precast connection is capable of exceeding the energy absorption of precast walls subjected to dynamic load, thereby improving its resistance behavior in all principal directions.  相似文献   

Critical Zone Assessments of an Alluvial Aquifer System Using the Multi-influencing Factor (MIF) and Analytical Hierarchy Process (AHP) Models in Western Iran     

Taheri  Kamal  Missimer  Thomas M.  Taheri  Milad  Moayedi  Hossein  Mohseni Pour  Fathollah 《Natural Resources Research》2020,29(2):1163-1191

Natural Resources Research - Many arid regions in the world suffer from over-exploitation of local groundwater resources leading to the degradation of freshwater aquifer systems, drying of spring...  相似文献   

Polar wander of Mars: Evidence from giant impact basins     

Jafar Arkani-Hamed 《Icarus》2009,204(2):489-498

We investigate the polar wander of Mars in the last ∼4.2 Ga. We identify two sets of basins from the 20 giant impact basins reported by Frey [Frey, H., 2008. Geophys. Res. Lett. 35, L13203] which trace great circles on Mars, and propose that the great circles were the prevailing equators of Mars at the impact times. Monte Carlo tests are conducted to demonstrate that the two sets of basins are most likely not created by random impacts. Also, fitting 63,771 planes to randomly selected sets of 5, 6, or 7 basins indicated that the identified two sets are unique. We propose three different positions for the rotation pole of Mars, besides the present one. Accordingly, Tharsis bulge was initially formed at ∼50 N and moved toward the equator while rotating counterclockwise due to the influence of the two newly forming volcanic constructs, Alba Patera and Elysium Rise. The formation of the giant impact basins, subsequent mass concentrations (mascons) in Argyre, Isidis, and Utopia basins, and surface masses of volcanic mountains such as Ascraeus, Pavonis, Arsia and Olympus, caused further polar wander which rotated Tharsis bulge clockwise to arrive at its present location. The extensive polar motion of Mars during 4.2-3.9 Ga implies a weak lithosphere on a global scale, deduced from a total of 72,000 polar wander models driven by Tharsis bulge, Alba Patera and Elysium Rise as the major mass perturbations. Different compensation states, 0-100%, are examined for each of the surface loads, and nine different thicknesses are considered for an elastic lithosphere. The lithosphere must have been very weak, with an elastic thickness of less than 5 km, if the polar wander was driven by these mass perturbations.  相似文献   

Characterization of a Sedimentary Soft Rock by a Small In-Situ Triaxial Test     

Abbas Taheri  Kazuo Tani 《Geotechnical and Geological Engineering》2010,28(3):241-249

To measure the shear strength and deformability of a sedimentary soft rock, a small down-hole in-situ triaxial testing method is developed. The apparatus consists of a triaxial cell and an axial loading device which enables testing at any depth. In this method, a columnar specimen of diameter 90 mm and 285 mm height can be sheared at the bottom of a drill hole. A series of tests were conducted at a 50 m deep experimental cavern. The test gallery is contained in mudstone with some inter-bedded thin sand layers. The tests were done in three different depths in a borehole by a multiple-step loading method. The new testing method was successful to measure stress–strain relation of rock mass. The test results demonstrated that the multiple-step loading method is acceptable in mudstone formation, if an appropriate criterion for load reversal is selected to recognize the instant of failure by stress–strain relation during loading. In addition, different results for mechanical properties of mudstone rock mass were observed in the specimens contained sand layers. It is also concluded that, the same loading method is not successful if a sand layer is located in the middle of the specimen due to large damage induced in early stages of loading.  相似文献   

Response of sediment-dwelling annelida community in relation to geochemical parameters in the Gorgan Bay,Caspian Sea     

K. D. Bastami  M. Taheri  H. Bagheri  M. Y. Foshtomi  S. Ganji  S. Haghparast  F. Soltani  A. Hamzehpoor  B. Karimi 《International Journal of Environmental Science and Technology》2014,11(7):2025-2036

This study aimed to investigate the population of annelida communities in relation to environmental factors and heavy metals accumulated in sediments of the Gorgan Bay. The pollution load index and potential ecological risk (PER) were calculated. The results indicated mean concentrations (ppm) of heavy metals were (mean ± SD) Pb: 11.5 ± 4.88, Cu: 18 ± 8.83, Zn: 42 ± 22.15, Ni: 29.20 ± 14.68, Co: 10.56 ± 14.68, As: 7.77 ± 2.12, Sr: 1,449 ± 902.59 and V: 26.64 ± 10.25. Considering PER, sediments of the Gorgan Bay had low ecological risk. Based on abundance data, dominant species were Streblospio gynobranchiata, Nereis diversicolor, Tubificoides fraseri and Tubificidae unknown, respectively. Results of redundancy analysis displayed that T. fraseri and N. diversicolor were associated with high values of Sr. All the species were negatively correlated with As. There were positive correlation between S. gynobranchiata and N. diversicolor with values of clay, salinity, depth and silt. The present study provided the relative importance of heavy metals and environmental variables which partly assist in structuring assemblages of annelida in a transitional area.  相似文献   

Groundwater quality in the semi‐arid region of the Chahardouly basin,West Iran     

A. Taheri Tizro  K.S. Voudouris 《水文研究》2008,22(16):3066-3078

Chahardouly basin is located in the western part of Iran and is characterized by semi‐arid climatic conditions and scarcity in water resources. The main aquifer systems are developed within alluvial deposits. The availability of groundwater is rather erratic owing to the occurrence of hard rock formation and a saline zone in some parts of the area. The aquifer systems of the area show signs of depletion, which have taken place in recent years due to a decline in water levels. Groundwater samples collected from shallow and deep wells were analysed to examine the quality characteristics of groundwater. The major ion chemistry of groundwater is dominated by Ca²⁺ and HCO₃^?, while higher values of total dissolved solids (TDS) in groundwater are associated with high concentrations of all major ions. An increase in salinity is recorded in the down‐gradient part of the basin. The occurrence of saline groundwater, as witnessed by the high electrical conductivity (EC), may be attributed to the long residence time of water and the dissolution of minerals, as well as evaporation of rainfall and irrigation return flow. Based on SAR values and sodium content (%Na), salinity appears to be responsible for the poor groundwater quality, rendering most of the samples not suitable for irrigation use. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Comparative analysis on macroscale material models for the prediction of masonry in-plane behavior     

Zizi  Mattia  Chisari  Corrado  Rouhi  Jafar  De Matteis  Gianfranco 《Bulletin of Earthquake Engineering》2022,20(2):963-996

Bulletin of Earthquake Engineering - Simulating the mechanical behavior of masonry structures with reasonable approximation using numerical models is a complex issue, mainly due to the...  相似文献   

Unified bounding surface model for monotonic and cyclic behaviour of clay and sand     

Moghadam  Seyed Iman  Taheri  Ehsan  Ahmadi  Morteza  Ghoreishian Amiri  Seyed Ali 《Acta Geotechnica》2022,17(10):4359-4375

Acta Geotechnica - This paper presents a constitutive model enabled to simulate monotonic and cyclic behaviour of clay and sand in a unified framework. The bounding surface concept has been...  相似文献   

An integrated GIS-based approach for geohazards risk assessment in coal mines     

Vahid Vaziri  Jafar Khademi Hamidi  Ahmad Reza Sayadi 《Environmental Earth Sciences》2018,77(1):29

From the viewpoint of safety in underground coal mining, the most suitable mining panel is the one with minimum geological structures, the right machinery, and equipment selection, trained employee, and proficient stope management. Since the ground parameters are uncontrollable and inherent uncertainties exist, a high percent of risk will usually accompany the underground coal mining activities. The main purpose of this study is to present a geological–geotechnical risk assessment model for identification of high risk-prone areas in underground coal mines using an integrated GIS-geostatistics system. Tabas as the first mechanized and largest underground coal mine in Iran was selected as a case study in this study. Gas content of coal seam, Coal Mine Roof Rating (CMRR), initial in situ stress state, fault throw, and orientation were selected as hazard/risk factors. For estimating the amount of coal seam gas content, CMRR and initial in situ stress in unsampled areas and providing the prediction maps, geostatistics module in ArcGIS was used. Rock engineering system–interaction matrix method was used for attribute weight assignment. Next, the attribute layers were weighted, rated, and overlaid to create a final map of geohazards risk. The analysis results of final risk map indicate that about 45% of under study area is prone to high to very high geohazards risk. Comparison of the results with experiences obtained during the early part of the mine and mined-out panels showed generally good agreement with promising ideas. This highlights the potential application of the GIS-based approach for hazards detection and geohazards risk assessment in underground coal mines.  相似文献