This study employs similar simulation testing and discrete element simulation coupling to analyze the failure and deformation processes of a model coal seam's roof.The caving area of the overburden rock is divided...This study employs similar simulation testing and discrete element simulation coupling to analyze the failure and deformation processes of a model coal seam's roof.The caving area of the overburden rock is divided into three zones:the delamination fracture zone,broken fracture zone,and compaction zone.The caving and fracture zones'heights are approximately 110 m above the coal seam,with a maximum subsidence of 11 m.The delamination fracture zone's porosity range is between 0.2 and 0.3,while the remainder of the roof predominantly exhibits a porosity of less than 0.1.In addition,the numerical model's stress analysis revealed that the overburden rock's displacement zone forms an'arch-beam'structure starting from 160 m,with the maximum and minimum stress values decreasing as the distance of advancement increases.In the stress beam interval of the overburden rock,the maximum value changes periodically as the advancement distance increases.Based on a comparative analysis between observable data from on-site work and numerical simulation results,the stress data from the numerical simulation are essentially consistent with the actual results detected on-site,indicating the validity of the numerical simulation results.展开更多
Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete（SEMDC）was established.The existing experimentalmethods for durability of concrete were summarized,a...Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete（SEMDC）was established.The existing experimentalmethods for durability of concrete were summarized,and the merits and demerits of these experimentalmethods were analyzed.Major factors affecting the durability of concrete were found through literature review.These factors were analyzed and the similarity criteria were established according to the similarity theory,and then the SEMDC was established according to the rules of these criteria.The various influentialfactors of the experimentalmethod were analyzed and the merits and demerits of this new experimentalmethod were discussed.According to SEMDC,changing the geometry shrinkage ratio was the only way to accelerate the test in order to keep the experiment similar to the reality.There were few other parameters which need to be changed in SEMDC,making the test easy to be achieved.According to SEMDC,time shrinkage ratio was the square of geometric shrinkage ratio,so an appropriate increase of the geometric shrinkage ratio could accelerate the test.Finally,an example of experimentaldesign for durability of concrete was devised theoretically base on SEMDC theory.展开更多
基金National Key R&D Program of China(2023YFC3009100,2023YFC3009102)National Natural Science Foundation of China(52304198)Open Fund of the National and Local Joint Engineering Research Center for Safe and Accurate Coal Mining(EC2021016).
文摘This study employs similar simulation testing and discrete element simulation coupling to analyze the failure and deformation processes of a model coal seam's roof.The caving area of the overburden rock is divided into three zones:the delamination fracture zone,broken fracture zone,and compaction zone.The caving and fracture zones'heights are approximately 110 m above the coal seam,with a maximum subsidence of 11 m.The delamination fracture zone's porosity range is between 0.2 and 0.3,while the remainder of the roof predominantly exhibits a porosity of less than 0.1.In addition,the numerical model's stress analysis revealed that the overburden rock's displacement zone forms an'arch-beam'structure starting from 160 m,with the maximum and minimum stress values decreasing as the distance of advancement increases.In the stress beam interval of the overburden rock,the maximum value changes periodically as the advancement distance increases.Based on a comparative analysis between observable data from on-site work and numerical simulation results,the stress data from the numerical simulation are essentially consistent with the actual results detected on-site,indicating the validity of the numerical simulation results.
基金Funded by the National Natural Science Foundation of China(Nos.50808173 and 51208504)
文摘Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete（SEMDC）was established.The existing experimentalmethods for durability of concrete were summarized,and the merits and demerits of these experimentalmethods were analyzed.Major factors affecting the durability of concrete were found through literature review.These factors were analyzed and the similarity criteria were established according to the similarity theory,and then the SEMDC was established according to the rules of these criteria.The various influentialfactors of the experimentalmethod were analyzed and the merits and demerits of this new experimentalmethod were discussed.According to SEMDC,changing the geometry shrinkage ratio was the only way to accelerate the test in order to keep the experiment similar to the reality.There were few other parameters which need to be changed in SEMDC,making the test easy to be achieved.According to SEMDC,time shrinkage ratio was the square of geometric shrinkage ratio,so an appropriate increase of the geometric shrinkage ratio could accelerate the test.Finally,an example of experimentaldesign for durability of concrete was devised theoretically base on SEMDC theory.
