Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This...Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This phenomenon has become a focal point in landslide research.Yet,there is a lack of studies on the failure modes and mechanisms of hidden,steep obliquely inclined bedding slopes.This study investigated the Shanyang landslide in Shaanxi Province,China.Using field investigations,laboratory tests of geotechnical parameters,and the 3DEC software,this study developed a numerical model of the landslide to analyze the failure process of such slopes.The findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of gravity.The landslide,initially following a dip angle with the support of a stable inclined rock mass,shifted direction under the influence of argillization in the weak interlayer,moving towards the apparent dip angle.The slide resistance effect of the karstic dissolution zone was increasingly significant during this process,with lateral friction being the primary resistance force.A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more pronounced.Notably,deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force,leading to the eventual buckling failure of the landslide.This study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide,highlighting the critical role of lateral friction from the karstic dissolution zone in its failure mechanism.These insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides.展开更多
The insertion torque of a dental implant is an important indicator for the primary stability of dental implants.Thus,the preoperative prediction for the insertion torque is crucial to improve the success rate of impla...The insertion torque of a dental implant is an important indicator for the primary stability of dental implants.Thus,the preoperative prediction for the insertion torque is crucial to improve the success rate of implantation surgery.In this present research,an alternative method for prediction of implant torque was proposed.First,the mechanical model for the insertion torque was established based on an oblique cutting process.In the proposed mechanical model,three factors,including bone quality,implant geometry and surgical methods were considered in terms of bone-quality coefficients,chip load and insertion speeds,respectively.Then,the defined bone-quality coefficients for cancellous bone with the computed tomography(CT)value of 235–245,345–355 and 415–425 Hu were obtained by a series of insertion experiments of IS and ITI implants.Finally,the insertion experiments of DIO implants were carried out to verify the accuracy of developed model.The predicted insertion torques calculated by the mechanical model were compared with those acquired by insertion experiments,with good agreement,the relative error being less than 15%.This method allows the insertion torque for different implant types to be quickly established and enhances prediction accuracy by considering the effects of implants’geometries and surgical methods.展开更多
Carbon fiber reinforced polymer(CFRP)and CFRP-based composite honeycomb sandwich structures are particularly sensitive to impact.The mechanical characteristics of composite honeycomb sandwich structures under oblique ...Carbon fiber reinforced polymer(CFRP)and CFRP-based composite honeycomb sandwich structures are particularly sensitive to impact.The mechanical characteristics of composite honeycomb sandwich structures under oblique impact are studied by numerical simulation and experiment.The oblique impact model is established,and the reliability of the model is verified by the oblique impact test.To further analyze the influence of structural parameters on energy absorption under oblique impact,the influence of impact angle,face sheet thickness and wall thickness of the honeycomb is numerically studied.The results show that the impact angle has an important effect on energy distribution.The structural parameters also have an effect on the peak contact force,contact time,and energy absorption,and the effect is different from normal impact due to the presence of frictional dissipation energy.Compared with normal impact,the debonding of oblique impact will be reduced,but the buckling range of the honeycomb core will be expanded.展开更多
In order to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines in China,we have analyzed the characteristics of spontaneous coal combustion and explain t...In order to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines in China,we have analyzed the characteristics of spontaneous coal combustion and explain theoretically the factors affecting spontaneous coal combustion,such as rock bursts,high temperatures,high ventilation resistance,slow advancing speed and large obliquity mining.Key technologies to prevent spontaneous combustion occurring in sharply inclined seams in deep mines are proposed;these include pouring water,stopping leakage in upper and lower corners of the working face,choking off the goaf and covering the coal.CO concentrations were controlled within two years to less than 15×10-6 at the upper corner by applying these technologies at the 1410 working face of the Huafeng coal mine.Our method has significant theoretical value and is of practical importance in controlling spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines.展开更多
A new non-simplified model of formation flying is derived in the presence of an oblate main- body and third-body perturbation. In the proposed model, considering the perturbation of the third- body in an inclined orbi...A new non-simplified model of formation flying is derived in the presence of an oblate main- body and third-body perturbation. In the proposed model, considering the perturbation of the third- body in an inclined orbit, the effect of obliquity （axial tilt） of the main-body is becoming important and has been propounded in the absolute motion of a reference satellite and the relative motion of a follower satellite. From a new point of view, J2 perturbed relative motion equations and considering a disturbing body in an elliptic inclined three dimensional orbit, are derived using Lagrangian mechanics based on accurate introduced perturbed reference satellite motion. To validate the accuracy of the model presented in this study, an auxiliary model was constructed as the Main-body Center based Relative Motion （MCRM） model. Finally, the importance of the main-body＇s obliquity is demonstrated by several examples related to the Earth-Moon system in relative motion and lunar satellite formation keeping. The main-body＇s obliquity has a remarkable effect on formation keeping in the examined in-track and projected circular orbit （PCO） formations.展开更多
基金jointly supported by the projects of the China Geological Survey(DD20230092,DD20201119)。
文摘Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This phenomenon has become a focal point in landslide research.Yet,there is a lack of studies on the failure modes and mechanisms of hidden,steep obliquely inclined bedding slopes.This study investigated the Shanyang landslide in Shaanxi Province,China.Using field investigations,laboratory tests of geotechnical parameters,and the 3DEC software,this study developed a numerical model of the landslide to analyze the failure process of such slopes.The findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of gravity.The landslide,initially following a dip angle with the support of a stable inclined rock mass,shifted direction under the influence of argillization in the weak interlayer,moving towards the apparent dip angle.The slide resistance effect of the karstic dissolution zone was increasingly significant during this process,with lateral friction being the primary resistance force.A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more pronounced.Notably,deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force,leading to the eventual buckling failure of the landslide.This study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide,highlighting the critical role of lateral friction from the karstic dissolution zone in its failure mechanism.These insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides.
基金Major Research&Development Program of Shandong Province(Grant No.2015GGX103043)Taishan Scholars Program of Shandong Province(Grant No.ts201712002).
文摘The insertion torque of a dental implant is an important indicator for the primary stability of dental implants.Thus,the preoperative prediction for the insertion torque is crucial to improve the success rate of implantation surgery.In this present research,an alternative method for prediction of implant torque was proposed.First,the mechanical model for the insertion torque was established based on an oblique cutting process.In the proposed mechanical model,three factors,including bone quality,implant geometry and surgical methods were considered in terms of bone-quality coefficients,chip load and insertion speeds,respectively.Then,the defined bone-quality coefficients for cancellous bone with the computed tomography(CT)value of 235–245,345–355 and 415–425 Hu were obtained by a series of insertion experiments of IS and ITI implants.Finally,the insertion experiments of DIO implants were carried out to verify the accuracy of developed model.The predicted insertion torques calculated by the mechanical model were compared with those acquired by insertion experiments,with good agreement,the relative error being less than 15%.This method allows the insertion torque for different implant types to be quickly established and enhances prediction accuracy by considering the effects of implants’geometries and surgical methods.
基金This research was supported by the National Natural Science Foundations of China(Nos.52175153,U1833116,51705468 and 11402234)the China Scholarship Council(CSC).
文摘Carbon fiber reinforced polymer(CFRP)and CFRP-based composite honeycomb sandwich structures are particularly sensitive to impact.The mechanical characteristics of composite honeycomb sandwich structures under oblique impact are studied by numerical simulation and experiment.The oblique impact model is established,and the reliability of the model is verified by the oblique impact test.To further analyze the influence of structural parameters on energy absorption under oblique impact,the influence of impact angle,face sheet thickness and wall thickness of the honeycomb is numerically studied.The results show that the impact angle has an important effect on energy distribution.The structural parameters also have an effect on the peak contact force,contact time,and energy absorption,and the effect is different from normal impact due to the presence of frictional dissipation energy.Compared with normal impact,the debonding of oblique impact will be reduced,but the buckling range of the honeycomb core will be expanded.
基金Projects 2007B53 supported by the Foundation for National Excellent Doctoral Dissertation of ChinaBK2008123 by the Natural Science Foundation of Jiangsu Province
文摘In order to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines in China,we have analyzed the characteristics of spontaneous coal combustion and explain theoretically the factors affecting spontaneous coal combustion,such as rock bursts,high temperatures,high ventilation resistance,slow advancing speed and large obliquity mining.Key technologies to prevent spontaneous combustion occurring in sharply inclined seams in deep mines are proposed;these include pouring water,stopping leakage in upper and lower corners of the working face,choking off the goaf and covering the coal.CO concentrations were controlled within two years to less than 15×10-6 at the upper corner by applying these technologies at the 1410 working face of the Huafeng coal mine.Our method has significant theoretical value and is of practical importance in controlling spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines.
文摘A new non-simplified model of formation flying is derived in the presence of an oblate main- body and third-body perturbation. In the proposed model, considering the perturbation of the third- body in an inclined orbit, the effect of obliquity （axial tilt） of the main-body is becoming important and has been propounded in the absolute motion of a reference satellite and the relative motion of a follower satellite. From a new point of view, J2 perturbed relative motion equations and considering a disturbing body in an elliptic inclined three dimensional orbit, are derived using Lagrangian mechanics based on accurate introduced perturbed reference satellite motion. To validate the accuracy of the model presented in this study, an auxiliary model was constructed as the Main-body Center based Relative Motion （MCRM） model. Finally, the importance of the main-body＇s obliquity is demonstrated by several examples related to the Earth-Moon system in relative motion and lunar satellite formation keeping. The main-body＇s obliquity has a remarkable effect on formation keeping in the examined in-track and projected circular orbit （PCO） formations.
