Axial chain rockbursts(ACRs)repeatedly occur in deep tunnels during drilling and blasting methodology(D&B)within locked-in stress zones,severely hindering construction progress.In extremely cases,ACRs can persist ...Axial chain rockbursts(ACRs)repeatedly occur in deep tunnels during drilling and blasting methodology(D&B)within locked-in stress zones,severely hindering construction progress.In extremely cases,ACRs can persist for 7−10 d and affect areas exceeding 20 m along tunnel axis.Through integrated geological investigations and microseismic(MS)monitoring,the geological characteristics,MS activity patterns,and formation mechanisms of ACRs were analyzed.In tectonically active regions,locked-in stress zones arise from interactions between multiple structural planes.Blasting dynamic disturbances during tunnel excavation in these zones trigger early slippage along structural planes and fractures in the surrounding rock,with MS events developing ahead of the working face.High-energy MS events dominate during the development and occurrence stages of ACRs,extending 20−30 m(3−4 tunnel diameters)ahead of the working face.Following the ACRs,low-energy MS events primarily occur behind the working face.Tensile fracturing is the predominant failure mode during ACRs.Shear and mixed fractures primarily occur within the ACRs zone during the intra-ACR phase.Monitoring MS event locations ahead of the working face provides a reliable approach for prewarning potential ACR-prone zones.展开更多
While brain computer interfaces(BCIs)ofer the potential of allowing those sufering from loss of muscle control to once again fully engage with their environment by bypassing the afected motor system and decoding user ...While brain computer interfaces(BCIs)ofer the potential of allowing those sufering from loss of muscle control to once again fully engage with their environment by bypassing the afected motor system and decoding user intentions directly from brain activity,they are prone to errors.One possible avenue for BCI performance improvement is to detect when the BCI user perceives the BCI to have made an unintended action and thus take corrective actions.Error-related potentials(ErrPs)are neural correlates of error awareness and as such can provide an indication of when a BCI system is not performing according to the user’s intentions.Here,we investigate the brain signals of an implanted BCI user sufering from locked-in syndrome(LIS)due to late-stage ALS that prevents her from being able to speak or move but not from using her BCI at home on a daily basis to communicate,for the presence of error-related signals.We frst establish the presence of an ErrP originating from the dorsolateral pre-frontal cortex(dLPFC)in response to errors made during a discrete feedback task that mimics the click-based spelling software she uses to communicate.Then,we show that this ErrP can also be elicited by cursor movement errors in a continuous BCI cursor control task.This work represents a frst step toward detecting ErrPs during the daily home use of a communications BCI.展开更多
Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician...Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician Chen Zongji, the locked-in stress problem in underground rock is simulated by the thermal expansion of hard rubber particles. The pore inclusion in rock is assumed to be uniformly distributed spherical cavities. Using the thermal stress theory, the stress of rock with a spherical pore inclusion is equivalent to the thermal stress generated by the spherical hard rubber inclusion. The elastic theory formula of the temperature increment and the equivalent pore pressure of the spherical hard rubber inclusion is derived. The numerical simulation of the rock mass model with a spherical hard rubber inclusion is carried out and compared to the theoretical calculation results<span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> the results show that they are consistent. The method proposed by this paper for simulating stress distribution in rock by thermal stress is reasonable and feasible</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> it has a positive meaning for further study of mechanic phenomenon of rock with micropore inclusion.</span>展开更多
基金Projects(52222810,52178383)supported by the National Natural Science Foundation of China。
文摘Axial chain rockbursts(ACRs)repeatedly occur in deep tunnels during drilling and blasting methodology(D&B)within locked-in stress zones,severely hindering construction progress.In extremely cases,ACRs can persist for 7−10 d and affect areas exceeding 20 m along tunnel axis.Through integrated geological investigations and microseismic(MS)monitoring,the geological characteristics,MS activity patterns,and formation mechanisms of ACRs were analyzed.In tectonically active regions,locked-in stress zones arise from interactions between multiple structural planes.Blasting dynamic disturbances during tunnel excavation in these zones trigger early slippage along structural planes and fractures in the surrounding rock,with MS events developing ahead of the working face.High-energy MS events dominate during the development and occurrence stages of ACRs,extending 20−30 m(3−4 tunnel diameters)ahead of the working face.Following the ACRs,low-energy MS events primarily occur behind the working face.Tensile fracturing is the predominant failure mode during ACRs.Shear and mixed fractures primarily occur within the ACRs zone during the intra-ACR phase.Monitoring MS event locations ahead of the working face provides a reliable approach for prewarning potential ACR-prone zones.
文摘While brain computer interfaces(BCIs)ofer the potential of allowing those sufering from loss of muscle control to once again fully engage with their environment by bypassing the afected motor system and decoding user intentions directly from brain activity,they are prone to errors.One possible avenue for BCI performance improvement is to detect when the BCI user perceives the BCI to have made an unintended action and thus take corrective actions.Error-related potentials(ErrPs)are neural correlates of error awareness and as such can provide an indication of when a BCI system is not performing according to the user’s intentions.Here,we investigate the brain signals of an implanted BCI user sufering from locked-in syndrome(LIS)due to late-stage ALS that prevents her from being able to speak or move but not from using her BCI at home on a daily basis to communicate,for the presence of error-related signals.We frst establish the presence of an ErrP originating from the dorsolateral pre-frontal cortex(dLPFC)in response to errors made during a discrete feedback task that mimics the click-based spelling software she uses to communicate.Then,we show that this ErrP can also be elicited by cursor movement errors in a continuous BCI cursor control task.This work represents a frst step toward detecting ErrPs during the daily home use of a communications BCI.
文摘Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician Chen Zongji, the locked-in stress problem in underground rock is simulated by the thermal expansion of hard rubber particles. The pore inclusion in rock is assumed to be uniformly distributed spherical cavities. Using the thermal stress theory, the stress of rock with a spherical pore inclusion is equivalent to the thermal stress generated by the spherical hard rubber inclusion. The elastic theory formula of the temperature increment and the equivalent pore pressure of the spherical hard rubber inclusion is derived. The numerical simulation of the rock mass model with a spherical hard rubber inclusion is carried out and compared to the theoretical calculation results<span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> the results show that they are consistent. The method proposed by this paper for simulating stress distribution in rock by thermal stress is reasonable and feasible</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> it has a positive meaning for further study of mechanic phenomenon of rock with micropore inclusion.</span>
