The deformation control of surrounding rock in gobside roadway with thick and hard roof poses a significant challenge to the safety and efficiency of coal mining.To address this issue,a novel approach combining direct...The deformation control of surrounding rock in gobside roadway with thick and hard roof poses a significant challenge to the safety and efficiency of coal mining.To address this issue,a novel approach combining directional and non-directional blasting techniques,known as combined blasting,was proposed.This study focuses on the experimental investigation of the proposed method in the 122108 working face in Caojiatan Coal Mine as the engineering background.The initial phase of the study involves physical model experiments to reveal the underlying mechanisms of combined blasting for protecting gob-side roadway with thick and hard roof.The results demonstrate that this approach effectively accelerates the collapse of thick and hard roofs,enhances the fragmentation and expansion coefficient of gangue,facilitates the filling of the goaf with gangue,and provides support to the overlying strata,thus reducing the subsidence of the overlying strata above the goaf.Additionally,the method involves cutting the main roof into shorter beams to decrease the stress and disrupt stress transmission pathways.Subsequent numerical simulations were conducted to corroborate the findings of the physical model experiments,thus validating the accuracy of the experimental results.Furthermore,field engineering experiments were performed,affirming the efficacy of the combined blasting method in mitigating the deformation of surrounding rock and achieving the desired protection of the gob-side roadway.展开更多
In the western part of the Netherlands due to several economic factors there is a strong pressure to extend the urban activities. This means that a large open peatland area of special ecological interest, the so calle...In the western part of the Netherlands due to several economic factors there is a strong pressure to extend the urban activities. This means that a large open peatland area of special ecological interest, the so called green heart, will be threatened more and more by urbanization. In this area diary farming predominates and the ecological value is largely dependant on this land use (meadow birds). Scenarios for future landscapes have been developed for this area taken into account different spatial lay out of urbanization. The consequences for nature were evaluated with a decision support system. The so called LEDESS (landscape ecological decision support system) links available landscape ecological knowledge to a geographical information system (GIS) to evaluate the scenarios. LEDESS is based on a deterministic concept of the ecotope dependent on physiotope, vegetation dynamics, target vegetation and management, and of faunal habitat requirements that are also dependent on vegetation structure. It also take 02/12/98s into account the accessibility of the landscape for migrating fauna species. It turns out that urbanization will deteriorate the existing fragmented landscape. As an answer to the scenarios of urbanization different options for nature restoration have been elaborated in additional scenarios. The consequences were evaluated again with the same computer model. The study has concluded that fragmentation can be compensated to some extend by enlargement of habitats, but the effectiveness depends highly upon the spatial allocation of the new habitats.展开更多
基金funding support from the National Natural Science Foundation of China(Grant Nos.52074298 and 52204164)Fundamental Research Funds for the Central Universities(Grant No.2022XJSB03).
文摘The deformation control of surrounding rock in gobside roadway with thick and hard roof poses a significant challenge to the safety and efficiency of coal mining.To address this issue,a novel approach combining directional and non-directional blasting techniques,known as combined blasting,was proposed.This study focuses on the experimental investigation of the proposed method in the 122108 working face in Caojiatan Coal Mine as the engineering background.The initial phase of the study involves physical model experiments to reveal the underlying mechanisms of combined blasting for protecting gob-side roadway with thick and hard roof.The results demonstrate that this approach effectively accelerates the collapse of thick and hard roofs,enhances the fragmentation and expansion coefficient of gangue,facilitates the filling of the goaf with gangue,and provides support to the overlying strata,thus reducing the subsidence of the overlying strata above the goaf.Additionally,the method involves cutting the main roof into shorter beams to decrease the stress and disrupt stress transmission pathways.Subsequent numerical simulations were conducted to corroborate the findings of the physical model experiments,thus validating the accuracy of the experimental results.Furthermore,field engineering experiments were performed,affirming the efficacy of the combined blasting method in mitigating the deformation of surrounding rock and achieving the desired protection of the gob-side roadway.
文摘In the western part of the Netherlands due to several economic factors there is a strong pressure to extend the urban activities. This means that a large open peatland area of special ecological interest, the so called green heart, will be threatened more and more by urbanization. In this area diary farming predominates and the ecological value is largely dependant on this land use (meadow birds). Scenarios for future landscapes have been developed for this area taken into account different spatial lay out of urbanization. The consequences for nature were evaluated with a decision support system. The so called LEDESS (landscape ecological decision support system) links available landscape ecological knowledge to a geographical information system (GIS) to evaluate the scenarios. LEDESS is based on a deterministic concept of the ecotope dependent on physiotope, vegetation dynamics, target vegetation and management, and of faunal habitat requirements that are also dependent on vegetation structure. It also take 02/12/98s into account the accessibility of the landscape for migrating fauna species. It turns out that urbanization will deteriorate the existing fragmented landscape. As an answer to the scenarios of urbanization different options for nature restoration have been elaborated in additional scenarios. The consequences were evaluated again with the same computer model. The study has concluded that fragmentation can be compensated to some extend by enlargement of habitats, but the effectiveness depends highly upon the spatial allocation of the new habitats.
