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The coupling effect of static and dynamic stress in fault structure areas exacerbates the risk of rock impact in underground fault areas. The stress distribution law and impact dynamic load response features of roadway surrounding rock in fault structure areas have significant peculiarities. At present, research on the impact of fault structures mainly focuses on the vicinity of the working face, but there is little research on the impact damage of roadways in fault structures. Taking the roadway in a deep buried high stress fault structure area of a mine in Shaanxi Province as the engineering background, the mechanical features of deformation and failure of the roadway surrounding rock in the fault structure area are analyzed. ① There is a significant stress barrier effect on the fault plane, and there are two special stress zones near the normal fault, namely the stress concentration zone in the hanging wall and the stress reduction zone in the lower wall. Due to the influence of the fault plane, the static load concentration stress of the roadway side shows an asymmetric distribution feature. The stress concentration on the side far from the fault plane is greater than that on the side near the fault plane, and the risk of impact damage to the surrounding rock of the roadway on this side increases. ② The fault plane has a significant barrier effect on the transmission of stress waves, and the dynamic load response of the hanging wall of the normal fault is greater than that of the lower wall. Due to the asymmetric distribution of stress on the two sides of the roadway, the dynamic load response of the right side is significantly greater than that of the left side. Based on the above features, a collaborative anti impact control technology of 'unloading (large diameter drilling pressure relief) - support (stepped reinforcement into layered energy absorption and anti impact support)' is proposed for the surrounding rock of the fault structure area roadway. The engineering test results show the following points. ① After adopting the 'unloading support' collaborative anti impact treatment measures for the roadway surrounding rock , the stress concentration areas of the two sides of the roadway are transferred to the deep part of the surrounding rock by 3-5 meters. The stress peak value is reduced by 18.5%-20.3%, and the stress concentration degree of the roadway surrounding rock is significantly reduced. ② Before the implementation of the 'unloading support' collaborative anti impact treatment measures, the deformation of the roadway roof, floor, and two sides are 856, 334, 325, and 567 mm, respectively. The deformation and damage of the roadway surrounding rock are severe. After adopting the 'unloading support' collaborative treatment measures, the deformation of the roadway surrounding rock decreases by 35.69%-62.03%, and the stability of the roadway surrounding rock is enhanced. ③ The coal powder content in the borehole is also significantly lower than the critical coal powder content, and the dynamic power of the roadway surrounding rock is reduced.

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

On 21 June 2022 (at 20:54:34UTC), a magnitude 6.0 (Richter scale) earthquake (depth 4 km) struck eastern Afghanistan, devastating parts of the Khost and Paktika provinces. With its epicentre located southwest of Khost city, more than 1000 people were killed and several thousands injured by the earthquake. Deformation modelling and finite-fault source characterisation provide essential information for seismic hazard management and advanced analysis of the seismicity in earthquake prone areas. The coseismic deformation, which occurred west of the NNE–SSW-trending North Waziristan–Bannu thrust fault zone, was assessed using dual-pass (ascending and descending) interferometric Sentinel-1 data. The line of sight (LOS) displacement estimated from ascending pass imagery ranged from + 0.38 m to − 0.16 m. The descending pass LOS displacement ranged from + 0.10 m to − 0.13 m. The displacement components are resolved in vertical and east–west directions using ascending and descending passes. The displacement is predominantly westward with a strong upliftment component, thus indicating an SW-trending oblique slip movement of the fault. Inversion modelling was done to derive the seismic source characteristics from DInSAR displacement values using an elastic dislocation model. The linear inversion model converges at a single fault source solution with a dip and strike of ~ 62° and 216° N, respectively, having a rake of 25° N. The distributed slip values vary between 0 and 2.25 m. The inversion model results in a moment magnitude of 6.18 and a geodetic moment of 2.06 × 1018 Nm, comparable to those derived using teleseismic body wave data by USGS. Damage assessment using optical data from the Worldview-1 satellite substantiates that the building damages are located primarily within the zone of surface deformation. [ABSTRACT FROM AUTHOR]

For one hundred earthquakes （5.0≤MW≤6.9） that occurred around the epicenter of the 2010 Bio-Bío, Chile MW8.8 earthquake from 1 January 1990 to 26 February 2010, their focal mechanism solutions were used to calculate the friction coefficient on the fault plane and the friction coefficient as a function of time. The results show that within the period of four years and two months from the beginning of 2006 until the occurrence of the Bio-Bío mainshock the friction coefficient around the epicentral area showed a decreasing trend, dropped from about 0.73 at the beginning of 2006 to about 0.4 immediately towards the occurrence of the Bio-Bío mainshock, with a relative decrease of 45.2%. It will be of great significance for understanding the occurrence process of strong earthquakes and earthquake prediction.

The Samos (Sisam) Island earthquake of October 30, 2020 (11:51:25 UTC, Mw = 7.0, ML = 6.6, depth = 12 km) was a major earthquake with an epicenter in the Aegean Sea, ~ 10 km north of Samos Island and ≥ 40 km from the Aegean region of Turkey. The main stages of this study were the analysis of the aftershock regime of the earthquake, the correlation of this regime with the kinematics and the determination of seismic wave propagation and aftershock duration. In the subsequent 2 months, there were 4783 aftershock earthquakes (1.0 ≤ ML ≤ 5.3) within the earthquake's deformation zone. The cause of the mainshock was an E-W oriented normal faulting, and showed seismotectonic behavior compatible with the active tectonics of western Anatolia. According to the epicenter map of the aftershocks, the October 30, 2020, Samos earthquake process resulted in crust deformation over a total geographical area of 75 km × 41 km. The results of the seismic source propagation showed that there was no spatially or temporally correlated advance in dominant energy release observed around the mainshock hypocenter. A stable decay of aftershock activity was observed from the spatial and temporal analyses of the aftershocks that occurred within 2 months of the mainshock event. Moreover, with the proposed method of this study using the completeness plane technique to estimate the duration of aftershock activity allowed aftershocks to be estimated to last for ~ 2 years. For validation, this method was applied to two previous earthquakes with different faulting mechanisms. [ABSTRACT FROM AUTHOR]

Copyright of Bistua: Revista de la Facultad de Ciencias Básicas is the property of Facultad de Ciencias Basicas de la Universidad de Pamplona and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the barrier effect and its mechanism of steep fault plane on rock mass movement caused by mining, based on the numerical simulation method, the influence of fault on displacement field and stress field of surrounding rock is analyzed when the goaf is located in the hanging wall and footwall respectively. The results show that under the assumed conditions, the fault plane within the influence scope of mining destroys the continuity and coordination of rock mass movement and deformation, affects the propagation of surrounding rock stress, and has a certain barrier effect; the displacement and stress difference of surrounding rock on both sides of the fault plane caused by the upper wall mining is larger than that caused by the lower wall mining, and the effect of mining on the release of surrounding pressure is stronger. The occurrence mechanism of the barrier effect of the steep fault plane on the rock movement is revealed. The research results are of great significance to the determination of rock mass movement range under the influence of faults. [ABSTRACT FROM AUTHOR]