To determine reasonable distance of gas pre-drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants,the pa...To determine reasonable distance of gas pre-drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants,the paper conducted the numerical simulation of pre-drainage gas in drillings along coal seam, studied the relationship of adsorption constants and permeability, gas pressure, and effective drainage radius of coal seams, and applied the approach to the layout of pre-drainage gas drillings in coal seams. The results show that the permeability of coal seams is on the gradual increase with time, which is divided into three sections according to the increase rate: the drainage time 0–30 d is the sharp increase section;30–220 d is the gradual increase section; and the time above 200 d is the stable section. The permeability of coal seams is in negative linear and positive exponent relation with volume adsorption constant VLand pressure adsorption constant PL, respectively. The effective drainage radius is in negative linear relation with VLand in positive exponent relation with PL. Compared with the former design scheme, the engineering quantity of drilling could be reduced by 25%.展开更多
Glacial lake outburst floods(GLOFs)are increasingly frequent under warming and degradation,exerting profound impacts on regional ecosystems,geomorphology,and human systems.Ice-dammed lakes account for nearly 70% of GL...Glacial lake outburst floods(GLOFs)are increasingly frequent under warming and degradation,exerting profound impacts on regional ecosystems,geomorphology,and human systems.Ice-dammed lakes account for nearly 70% of GLOFs worldwide,yet their dynamics remain poorly understood in remote regions such as the interior Tibetan Plateau.Here,we present the first systematic assessment of the evolution and drainage of ice-dammed lakes across the region using multi-source satellite imagery.Between 1973 and 2024,the number of ice-dammed lakes increased from 256 to 323,while the total area declined from 22.66±0.93 km^(2) to 20.43±1.6 km^(2) due to repeated drainage and diminished reservoir capacity.Newly formed lakes tended to shift toward higher elevations.A total of 775 previously unreported GLOFs were detected based on abrupt lake area loss.Bayesian regression reveals a sharp rise in GLOF frequency,from an average of 11 GLOFs per year during 1990-1994 to 42.6 GLOFs per year during 2020-2024.Meanwhile,GLOF timing has shifted earlier by 9.07±3.71 days,and pre-drainage lake areas declined by 0.02±0.01 km^(2) compared to 1990.These findings highlight the evolving behavior of ice-dammed lakes in response to climate change and glacial recession,with important implications for regional cryospheric research and disaster mitigation.展开更多
基金Financial support for this work,provided by the National Natural Science Foundation of China(Nos.51327007,51104118 and51204134)Shaanxi Province Youth Science and Technology Star Project of China(2014KJXX69)
文摘To determine reasonable distance of gas pre-drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants,the paper conducted the numerical simulation of pre-drainage gas in drillings along coal seam, studied the relationship of adsorption constants and permeability, gas pressure, and effective drainage radius of coal seams, and applied the approach to the layout of pre-drainage gas drillings in coal seams. The results show that the permeability of coal seams is on the gradual increase with time, which is divided into three sections according to the increase rate: the drainage time 0–30 d is the sharp increase section;30–220 d is the gradual increase section; and the time above 200 d is the stable section. The permeability of coal seams is in negative linear and positive exponent relation with volume adsorption constant VLand pressure adsorption constant PL, respectively. The effective drainage radius is in negative linear relation with VLand in positive exponent relation with PL. Compared with the former design scheme, the engineering quantity of drilling could be reduced by 25%.
基金supported by the National Natural Science Foundation of China(Grant Nos.424B2002,U23A2011)National Key R&D Program of China(Grant No.2024YFF0808603)Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(Grant Nos.2024QZKK0500,2024QZKK0400).
文摘Glacial lake outburst floods(GLOFs)are increasingly frequent under warming and degradation,exerting profound impacts on regional ecosystems,geomorphology,and human systems.Ice-dammed lakes account for nearly 70% of GLOFs worldwide,yet their dynamics remain poorly understood in remote regions such as the interior Tibetan Plateau.Here,we present the first systematic assessment of the evolution and drainage of ice-dammed lakes across the region using multi-source satellite imagery.Between 1973 and 2024,the number of ice-dammed lakes increased from 256 to 323,while the total area declined from 22.66±0.93 km^(2) to 20.43±1.6 km^(2) due to repeated drainage and diminished reservoir capacity.Newly formed lakes tended to shift toward higher elevations.A total of 775 previously unreported GLOFs were detected based on abrupt lake area loss.Bayesian regression reveals a sharp rise in GLOF frequency,from an average of 11 GLOFs per year during 1990-1994 to 42.6 GLOFs per year during 2020-2024.Meanwhile,GLOF timing has shifted earlier by 9.07±3.71 days,and pre-drainage lake areas declined by 0.02±0.01 km^(2) compared to 1990.These findings highlight the evolving behavior of ice-dammed lakes in response to climate change and glacial recession,with important implications for regional cryospheric research and disaster mitigation.
