This article adopts three artificial intelligence techniques, Gaussian Process Regression（GPR）, Least Square Support Vector Machine（LSSVM） and Extreme Learning Machine（ELM）, for prediction of rock depth（d） at ...This article adopts three artificial intelligence techniques, Gaussian Process Regression（GPR）, Least Square Support Vector Machine（LSSVM） and Extreme Learning Machine（ELM）, for prediction of rock depth（d） at any point in Chennai. GPR, ELM and LSSVM have been used as regression techniques.Latitude and longitude are also adopted as inputs of the GPR, ELM and LSSVM models. The performance of the ELM, GPR and LSSVM models has been compared. The developed ELM, GPR and LSSVM models produce spatial variability of rock depth and offer robust models for the prediction of rock depth.展开更多
To solve the technical cruxes of the conventional system in deep rock mass, an automatic testing system for hydraulic fracturing that includes a single tube for hydraulic loop, a pressure-relief valve, central-tubeles...To solve the technical cruxes of the conventional system in deep rock mass, an automatic testing system for hydraulic fracturing that includes a single tube for hydraulic loop, a pressure-relief valve, central-tubeless packers, and a multichannel real-time data acquisition system was used for in-situ stresses measurement at great depths （over 1000 m） in a coalfield in Juye of Northern China. The values and orientations of horizontal principal stresses were determined by the new system. The virgin stress field and its distributing law were decided by the linear regression from the logged 37 points in seven boreholes. Besides, the typical boreholes arranged in both the adjacent zone and far away zone of the faults were analyzed, respectively. The results show that a stress concentration phenomenon and a deflection in the orientation of the maximal horizontal stress exist in the adjacent zone of the faults, which further provides theoretical basis for design and optimization of mining.展开更多
This paper presents some questions to the formula of pressure=depth×specific gravity from the viewpoint that the hydrostatic pressure is equal to the gravity of overlying rocks and the rocks in a static fluid sta...This paper presents some questions to the formula of pressure=depth×specific gravity from the viewpoint that the hydrostatic pressure is equal to the gravity of overlying rocks and the rocks in a static fluid state, which is drawn from the research and analysis of the research field and the corresponding problems of the pressure state in the deep crust and the formation depth of the UHP metamorphic rocks. In this research, the underground rocks are considered as the solid possessing some rheological behaviors to discuss the polysource stress state and to obtain a more reasonable method for the calculation of depths using the model of the unbalanced force solid. It is suggested from this paper that the P/SW method for the calculation of the ultrahigh pressure stemming only from the gravity has obviously overstated the formation depth of the UHP metamorphism. The formation model emphasizing the effect of the gravity, the tectonic force and the metamorphic force of the facies change concludes that such UHP minerals as coesite may have been produced in the inner crust.展开更多
The formation depth of metamorphic rocks in the Dabie ultrahigh pressure metamorphic (UHPM) zone influences not only our understanding of formation mechanism and evolution processes of collision orogenic belt, but...The formation depth of metamorphic rocks in the Dabie ultrahigh pressure metamorphic (UHPM) zone influences not only our understanding of formation mechanism and evolution processes of collision orogenic belt, but also the studies on earth's interior and geodynamic processes. In this study, the isotopic data of metamorphic rocks in the Dabie UHPM zone are discussed to give constraints on the formation depth in the Dabie UHPM zone. The ε Sr of eclogite in the Dabie UHPM zone varies from 18 to 42, and the ε Nd varies from -6.1 to -17, both of them show the characters of isotopic disequilibrium. The oxygen isotope studies indicate that the protoliths of these UHPM rocks have experienced oxygen isotope exchange with meteoric water (or sea water) before metamorphism and no significant changes in the processes of metamorphism on their oxygen isotope composition have been recorded in these rocks. Except for one sample from Bixiling, all samples of eclogite from Dabie UHPM zone show the 3He 4He ratios from 0.79×10 -7 to 9.35×10 -7 , indicating the important contribution of He from continental crust. All Sr, Nd, O and He isotopic studies indicate that the UHPM rocks retain the isotopic characteristics of their protoliths of crust origin. No significant influence of mantle materials has been found in these metamorphic rocks. Trying to explain above isotopic characteristics, some researchers assume that the speeds of dipping thrust and uplifting of rocks were both very high. In this condition, there will not be enough time for isotopic exchange between crust protolith and mantle materials. Therefore, we can not see the tracer of mantle materials in these UHPM rocks. However, this assumption can not be justified with available knowledge. Firstly, it was estimated that the whole process of UHPM took at least 15 Ma. During such a long period, and at the metamorphic temperature of ≥700 ℃, the protolith of crust origin can not escape from isotopic exchange with mantle materials if the UHPM have happened in the mantle depth of ≥100 km. In contrast, all problems will be dismissed if we assume that the UHPM have happened at the depth still in crust.展开更多
To ensure the stability of a tunnel during construction, rock bolts are usually installed, which affects the stress distribution around the tunnel. Therefore, it is necessary to study the effects of rock bolting on th...To ensure the stability of a tunnel during construction, rock bolts are usually installed, which affects the stress distribution around the tunnel. Therefore, it is necessary to study the effects of rock bolting on the stress distribution around the tunnel. In this article, the effects of rock bolting on the stress distribution around the tunnel, including the pesition and orientation of bolts, the overburden depths, and the bolt lengths, are simulated using the ANSYS software with an elnstoplastic model. The effect of multiple bolts of 2 m and 1 m lengths on the stress distribution in the roof and on the lateral sides of a tunnel and at different overburden depths is considered. An important finding is that the tensile stress region that is very dangerous for rock in the bottom of the tunnel grows rapidly with increasing overburden depths when rock bolts are installed only in the roof or on the lateral sides of a tunnel. The determination of the length of the rock bolt used around a tunnel is dependent on the loads and the integrity of the rock mass around the tunnel. In addition, rock bolting around the tunnel can obviously reduce the coefficients and the size of the region of stress concentration, especially when installed in high-stress areas. This fact is very important and essential for the design of tunnels and ensures engineering safety in tunnel engineering.展开更多
One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets...One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets are basically used to increase the rock cutting efficiency.However,there are no mature recommendations for selection of rational parameters,and the relationship between indicators of rock cutting efficiency and parameters of pulsed water jet is still not established.In this context,we aimed at developing a generalized equation for calculating rock cutting efficiency,in which all the major parameters in consideration of rock cutting process are included.Then,a calibration of the rational parameters of rock cutting by pulsed water jets was conducted.The results are likely helpful for increasing productivity and reducing energy consumption.展开更多
According to the regression analysis of measured stress data in magmatite,sedimentary and metamorphic rock all over the world,it is found that the stress state in the three rocks is different and closely related to it...According to the regression analysis of measured stress data in magmatite,sedimentary and metamorphic rock all over the world,it is found that the stress state in the three rocks is different and closely related to its formation.The relationships among the stress and depth and the Young's modulus of rock are also discussed and the results show that stress can increase with the Young's modulus.展开更多
By building a tunnel model with a semi-circular crown, the asymmetric rock pressure applied to the shallow tunnel in strata with inclined ground surface is analyzed. Formulae, which not only include the parameters .re...By building a tunnel model with a semi-circular crown, the asymmetric rock pressure applied to the shallow tunnel in strata with inclined ground surface is analyzed. Formulae, which not only include the parameters .related to both tunnel structure and surrounding rock mass, but the overburden depth, are developed. The computation for four tunnel models show that the method presented is feasible and convenient. Furthermore, the influence of the overburden depth on the rock pressure is elaborated, and the criterion to identify the deep or shallow tunnels is formulated as well.展开更多
In the previous work of the present study,moment tensors of 11 major earthquakes in the Qinghai-Xizang Plateau and its surrounding region from 1966 to 1980 are estimated by generalized inversion technique.The seismic ...In the previous work of the present study,moment tensors of 11 major earthquakes in the Qinghai-Xizang Plateau and its surrounding region from 1966 to 1980 are estimated by generalized inversion technique.The seismic source time function and focal depth are immediately determined in the inversion.The results indicated that all earthquakes investigated here are shallow events within the upper crust.The purpose of this paper is to present a summary of the distribution of focal depths of earthquakes in and near the Qinghai-Xizang Plateau from the above result,combining the focal depths of 78 significant earthquakes from 1964 to 1986,which are relocated individually by other authors,as well as to discuss its tectonic implication.展开更多
文摘This article adopts three artificial intelligence techniques, Gaussian Process Regression（GPR）, Least Square Support Vector Machine（LSSVM） and Extreme Learning Machine（ELM）, for prediction of rock depth（d） at any point in Chennai. GPR, ELM and LSSVM have been used as regression techniques.Latitude and longitude are also adopted as inputs of the GPR, ELM and LSSVM models. The performance of the ELM, GPR and LSSVM models has been compared. The developed ELM, GPR and LSSVM models produce spatial variability of rock depth and offer robust models for the prediction of rock depth.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50490271)
文摘To solve the technical cruxes of the conventional system in deep rock mass, an automatic testing system for hydraulic fracturing that includes a single tube for hydraulic loop, a pressure-relief valve, central-tubeless packers, and a multichannel real-time data acquisition system was used for in-situ stresses measurement at great depths （over 1000 m） in a coalfield in Juye of Northern China. The values and orientations of horizontal principal stresses were determined by the new system. The virgin stress field and its distributing law were decided by the linear regression from the logged 37 points in seven boreholes. Besides, the typical boreholes arranged in both the adjacent zone and far away zone of the faults were analyzed, respectively. The results show that a stress concentration phenomenon and a deflection in the orientation of the maximal horizontal stress exist in the adjacent zone of the faults, which further provides theoretical basis for design and optimization of mining.
文摘This paper presents some questions to the formula of pressure=depth×specific gravity from the viewpoint that the hydrostatic pressure is equal to the gravity of overlying rocks and the rocks in a static fluid state, which is drawn from the research and analysis of the research field and the corresponding problems of the pressure state in the deep crust and the formation depth of the UHP metamorphic rocks. In this research, the underground rocks are considered as the solid possessing some rheological behaviors to discuss the polysource stress state and to obtain a more reasonable method for the calculation of depths using the model of the unbalanced force solid. It is suggested from this paper that the P/SW method for the calculation of the ultrahigh pressure stemming only from the gravity has obviously overstated the formation depth of the UHP metamorphism. The formation model emphasizing the effect of the gravity, the tectonic force and the metamorphic force of the facies change concludes that such UHP minerals as coesite may have been produced in the inner crust.
文摘The formation depth of metamorphic rocks in the Dabie ultrahigh pressure metamorphic (UHPM) zone influences not only our understanding of formation mechanism and evolution processes of collision orogenic belt, but also the studies on earth's interior and geodynamic processes. In this study, the isotopic data of metamorphic rocks in the Dabie UHPM zone are discussed to give constraints on the formation depth in the Dabie UHPM zone. The ε Sr of eclogite in the Dabie UHPM zone varies from 18 to 42, and the ε Nd varies from -6.1 to -17, both of them show the characters of isotopic disequilibrium. The oxygen isotope studies indicate that the protoliths of these UHPM rocks have experienced oxygen isotope exchange with meteoric water (or sea water) before metamorphism and no significant changes in the processes of metamorphism on their oxygen isotope composition have been recorded in these rocks. Except for one sample from Bixiling, all samples of eclogite from Dabie UHPM zone show the 3He 4He ratios from 0.79×10 -7 to 9.35×10 -7 , indicating the important contribution of He from continental crust. All Sr, Nd, O and He isotopic studies indicate that the UHPM rocks retain the isotopic characteristics of their protoliths of crust origin. No significant influence of mantle materials has been found in these metamorphic rocks. Trying to explain above isotopic characteristics, some researchers assume that the speeds of dipping thrust and uplifting of rocks were both very high. In this condition, there will not be enough time for isotopic exchange between crust protolith and mantle materials. Therefore, we can not see the tracer of mantle materials in these UHPM rocks. However, this assumption can not be justified with available knowledge. Firstly, it was estimated that the whole process of UHPM took at least 15 Ma. During such a long period, and at the metamorphic temperature of ≥700 ℃, the protolith of crust origin can not escape from isotopic exchange with mantle materials if the UHPM have happened in the mantle depth of ≥100 km. In contrast, all problems will be dismissed if we assume that the UHPM have happened at the depth still in crust.
文摘To ensure the stability of a tunnel during construction, rock bolts are usually installed, which affects the stress distribution around the tunnel. Therefore, it is necessary to study the effects of rock bolting on the stress distribution around the tunnel. In this article, the effects of rock bolting on the stress distribution around the tunnel, including the pesition and orientation of bolts, the overburden depths, and the bolt lengths, are simulated using the ANSYS software with an elnstoplastic model. The effect of multiple bolts of 2 m and 1 m lengths on the stress distribution in the roof and on the lateral sides of a tunnel and at different overburden depths is considered. An important finding is that the tensile stress region that is very dangerous for rock in the bottom of the tunnel grows rapidly with increasing overburden depths when rock bolts are installed only in the roof or on the lateral sides of a tunnel. The determination of the length of the rock bolt used around a tunnel is dependent on the loads and the integrity of the rock mass around the tunnel. In addition, rock bolting around the tunnel can obviously reduce the coefficients and the size of the region of stress concentration, especially when installed in high-stress areas. This fact is very important and essential for the design of tunnels and ensures engineering safety in tunnel engineering.
文摘One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets are basically used to increase the rock cutting efficiency.However,there are no mature recommendations for selection of rational parameters,and the relationship between indicators of rock cutting efficiency and parameters of pulsed water jet is still not established.In this context,we aimed at developing a generalized equation for calculating rock cutting efficiency,in which all the major parameters in consideration of rock cutting process are included.Then,a calibration of the rational parameters of rock cutting by pulsed water jets was conducted.The results are likely helpful for increasing productivity and reducing energy consumption.
文摘According to the regression analysis of measured stress data in magmatite,sedimentary and metamorphic rock all over the world,it is found that the stress state in the three rocks is different and closely related to its formation.The relationships among the stress and depth and the Young's modulus of rock are also discussed and the results show that stress can increase with the Young's modulus.
文摘By building a tunnel model with a semi-circular crown, the asymmetric rock pressure applied to the shallow tunnel in strata with inclined ground surface is analyzed. Formulae, which not only include the parameters .related to both tunnel structure and surrounding rock mass, but the overburden depth, are developed. The computation for four tunnel models show that the method presented is feasible and convenient. Furthermore, the influence of the overburden depth on the rock pressure is elaborated, and the criterion to identify the deep or shallow tunnels is formulated as well.
基金This project was spousored by the state science and Technology Commission ,China.
文摘In the previous work of the present study,moment tensors of 11 major earthquakes in the Qinghai-Xizang Plateau and its surrounding region from 1966 to 1980 are estimated by generalized inversion technique.The seismic source time function and focal depth are immediately determined in the inversion.The results indicated that all earthquakes investigated here are shallow events within the upper crust.The purpose of this paper is to present a summary of the distribution of focal depths of earthquakes in and near the Qinghai-Xizang Plateau from the above result,combining the focal depths of 78 significant earthquakes from 1964 to 1986,which are relocated individually by other authors,as well as to discuss its tectonic implication.
