The rock indentation tests by a conical pick were conducted to investigate the rock cuttability correlated to confining stress conditions and rock strength.Based on the test results,the regression analyses,support vec...The rock indentation tests by a conical pick were conducted to investigate the rock cuttability correlated to confining stress conditions and rock strength.Based on the test results,the regression analyses,support vector machine(SVM)and generalized regression neural network(GRNN)were used to find the relationship among rock cuttability,uniaxial confining stress applied to rock,uniaxial compressive strength(UCS)and tensile strength of rock material.It was found that the regression and SVM-based models can accurately reflect the variation law of rock cuttability,which presented decreases followed by increases with the increase in uniaxial confining stress and the negative correlation to UCS and tensile strength of rock material.Based on prediction models for revealing the optimal stress condition and determining the cutting parameters,the axial boom roadheader with many conical picks mounted was satisfactorily utilized to perform rock cutting in hard phosphate rock around pillar.展开更多
Among the triggering factors of postearthquake bedrock landslides, rainfall plays an important role. However, with slope variation, the mechanism of its effects on the failure of rock landslides is not dear. Here, fro...Among the triggering factors of postearthquake bedrock landslides, rainfall plays an important role. However, with slope variation, the mechanism of its effects on the failure of rock landslides is not dear. Here, from the viewpoint of fracture mechanics, and based on post-earthquake conditions, the mechanisms of crack propagation, water infiltration and development of the sliding surface were investigated. Then, according to the upper boundary theorem, the effects of water infiltrated into fractures on the stability of rock slopes were analyzed quantitatively. Finally, an example is presented to verify the theory. The results show that the propagation and coalescence of cracks and the lubrication of incipient sliding surfaces are the main causes of the failure of post-earthquake rock landslides in response to rainfall.展开更多
Based on the deformation characteristics of the roadways driven along goaf in fully mechanized top coal caving faces, the author considers that it is the key to ensure the stability of surrounding rocks of roadway dri...Based on the deformation characteristics of the roadways driven along goaf in fully mechanized top coal caving faces, the author considers that it is the key to ensure the stability of surrounding rocks of roadway driven along goaf to control the deformation during the period affected by mining. Considering the characteristics of the roadway layout in fully mechanized top coal caving faces, a technical scheme of destressing is put forward and the destressing effect is analyzed by using the software of Universal Distinct Element Code 3 0(UDEC 3 0).展开更多
The Tianhuashan Basin is one of the most important volcanic basins in the northern Wuyi,southeastern China,comprising two successive volcanic units,the Daguding Formation and the overlying Ehuling Formation,along with...The Tianhuashan Basin is one of the most important volcanic basins in the northern Wuyi,southeastern China,comprising two successive volcanic units,the Daguding Formation and the overlying Ehuling Formation,along with several small associated igneous intrusions.The Lengshuikeng super-large-scale Ag-Pb-Zn deposit,which is closely related to these volcanic-intrusive rocks,is located in the northwestern part of the basin.In order to understand the basin evolution and magmatism,we determined LA-ICP-MS U-Pb zircon ages for the volcanic successions and associated intrusive rocks.U-Pb zircon dating of volcanic units yielded precise ages of 144±1 Ma for crystal tuff in the lower member of the Daguding Formation,142±1 Ma for andesite within the upper member of the Daguding Formation,140±1 Ma for tuffite of the first(i.e.,lowermost) member of the Ehuling Formation,and 137±1 Ma for rhyolitic ignimbrite within the third volcano-stratigraphic member of the Ehuling Formation.Three types of intrusive igneous rocks(quartz syenite porphyry,K-feldspar granite porphyry,and rhyolite porphyry) yielded precise weighted mean 206 Pb/238 U ages of 144±1,140±1,and 140±1 Ma,respectively,suggesting that these intrusions along with the aforementioned volcanics were all emplaced during the Early Cretaceous.In addition,the weighted mean 206 Pb/238 U ages determined on zircon from two samples of a granite porphyry intrusion,which hosts ore mineralization of the Lengshuikeng Ag-Pb-Zn deposit,are 158±1 and 157±1 Ma,indicating emplacement in the Late Jurassic.These new geochronological results for igneous rocks of the Tianhuashan Basin constrain the timing of volcanic and plutonic activity in the basin,and have important implications for our understanding the tectonic history of the region,and for identifying metallogenic types and the timing of ore deposition of the Lengshuikeng deposit.展开更多
基金financial supports from the National Natural Science Foundation of China(Nos.51904333,51774326)。
文摘The rock indentation tests by a conical pick were conducted to investigate the rock cuttability correlated to confining stress conditions and rock strength.Based on the test results,the regression analyses,support vector machine(SVM)and generalized regression neural network(GRNN)were used to find the relationship among rock cuttability,uniaxial confining stress applied to rock,uniaxial compressive strength(UCS)and tensile strength of rock material.It was found that the regression and SVM-based models can accurately reflect the variation law of rock cuttability,which presented decreases followed by increases with the increase in uniaxial confining stress and the negative correlation to UCS and tensile strength of rock material.Based on prediction models for revealing the optimal stress condition and determining the cutting parameters,the axial boom roadheader with many conical picks mounted was satisfactorily utilized to perform rock cutting in hard phosphate rock around pillar.
基金supported by The National Basic Research Program of China (also called 973 Program) (Grant No. 2008CB425802)the National Natural Science Foundation of China (Grant No. 40872181)
文摘Among the triggering factors of postearthquake bedrock landslides, rainfall plays an important role. However, with slope variation, the mechanism of its effects on the failure of rock landslides is not dear. Here, from the viewpoint of fracture mechanics, and based on post-earthquake conditions, the mechanisms of crack propagation, water infiltration and development of the sliding surface were investigated. Then, according to the upper boundary theorem, the effects of water infiltrated into fractures on the stability of rock slopes were analyzed quantitatively. Finally, an example is presented to verify the theory. The results show that the propagation and coalescence of cracks and the lubrication of incipient sliding surfaces are the main causes of the failure of post-earthquake rock landslides in response to rainfall.
文摘Based on the deformation characteristics of the roadways driven along goaf in fully mechanized top coal caving faces, the author considers that it is the key to ensure the stability of surrounding rocks of roadway driven along goaf to control the deformation during the period affected by mining. Considering the characteristics of the roadway layout in fully mechanized top coal caving faces, a technical scheme of destressing is put forward and the destressing effect is analyzed by using the software of Universal Distinct Element Code 3 0(UDEC 3 0).
基金supported by the National Natural Science Foundation of China (Grant No. 40930419)Special Research Funding for the Public Benefit Sponsored by MLR (GrantNo. 200911007)
文摘The Tianhuashan Basin is one of the most important volcanic basins in the northern Wuyi,southeastern China,comprising two successive volcanic units,the Daguding Formation and the overlying Ehuling Formation,along with several small associated igneous intrusions.The Lengshuikeng super-large-scale Ag-Pb-Zn deposit,which is closely related to these volcanic-intrusive rocks,is located in the northwestern part of the basin.In order to understand the basin evolution and magmatism,we determined LA-ICP-MS U-Pb zircon ages for the volcanic successions and associated intrusive rocks.U-Pb zircon dating of volcanic units yielded precise ages of 144±1 Ma for crystal tuff in the lower member of the Daguding Formation,142±1 Ma for andesite within the upper member of the Daguding Formation,140±1 Ma for tuffite of the first(i.e.,lowermost) member of the Ehuling Formation,and 137±1 Ma for rhyolitic ignimbrite within the third volcano-stratigraphic member of the Ehuling Formation.Three types of intrusive igneous rocks(quartz syenite porphyry,K-feldspar granite porphyry,and rhyolite porphyry) yielded precise weighted mean 206 Pb/238 U ages of 144±1,140±1,and 140±1 Ma,respectively,suggesting that these intrusions along with the aforementioned volcanics were all emplaced during the Early Cretaceous.In addition,the weighted mean 206 Pb/238 U ages determined on zircon from two samples of a granite porphyry intrusion,which hosts ore mineralization of the Lengshuikeng Ag-Pb-Zn deposit,are 158±1 and 157±1 Ma,indicating emplacement in the Late Jurassic.These new geochronological results for igneous rocks of the Tianhuashan Basin constrain the timing of volcanic and plutonic activity in the basin,and have important implications for our understanding the tectonic history of the region,and for identifying metallogenic types and the timing of ore deposition of the Lengshuikeng deposit.
