Given the increasingly notable segmentation of underground space by existing subway tunnels, it is dif- ficult to effectively and adequately develop and utilize underground space in busy parts of a city. This study pr...Given the increasingly notable segmentation of underground space by existing subway tunnels, it is dif- ficult to effectively and adequately develop and utilize underground space in busy parts of a city. This study presents a combined construction technology that has been developed for use in underground spaces; it includes a deformation buffer layer, a special grouting technique, jump excavation by compart- ment, back-pressure portal frame technology, a reinforcement technique, and the technology of a steel portioning drum or plate. These technologies have been successfully used in practical engineering. The combined construction technology presented in this paper provides a new method of solving key techni- cal problems in underground spaces in effectively used cross-subway tunnels. As this technology has achieved significant economic and social benefits, it has valuable future applications.展开更多
Carpal tunnel syndrome (CTS) is the most common of all focal neuropathies. Electrodiagnostic (EXD) of CTS has advanced to include Combined Sensory Indexes (CSI) improving the specificity and sensitivity of EXD by empl...Carpal tunnel syndrome (CTS) is the most common of all focal neuropathies. Electrodiagnostic (EXD) of CTS has advanced to include Combined Sensory Indexes (CSI) improving the specificity and sensitivity of EXD by employing intra-hand comparative data. Ultrasound (US) is a popular tool for the assessment of CTS. Cross Sectional Area (CSA) is the most consistent US parameter, but as a single test, it has a similar false negative profile to EXD. This study describes a dual method of CTS interrogation by EXD and US with the results applied to a single numerical score;the Combined Median Score (CMS). This is the product of CSA of median nerve at Carpal Tunnel inlet and CSI. In a series of 100 suspected cases, standard EDX identified 89 positive cases, CSI identified 92 positives, CMS identified 95 positives. This new method further reduced the false negative rate in CTS.展开更多
The lateral response of combined pile-raft foundations(CPRFs)adjacent to tunnel excavation is a challenging problem owing to the complexity of the pile-raft connections.In current engineering practices,the impact of t...The lateral response of combined pile-raft foundations(CPRFs)adjacent to tunnel excavation is a challenging problem owing to the complexity of the pile-raft connections.In current engineering practices,the impact of these connections on the lateral performance of CPRFs is frequently overlooked,despite their importance.To address this issue,this study conducted three-dimensional finite element analyses to evaluate the contribution of pile-raft connections to the tunnelling-induced lateral performance of CPRFs in saturated clay.In the analysis,both passive and active loading at the pile head could be considered by varying the tunnel depth.Several parameter studies,such as relative pile-raft modulus,pile embedded modulus,pile embedded depths,and pile shaft skin friction,were conducted to determine the optimal design parameters for CPRFs.The results indicate that pile-raft connections significantly affect the tunnellinginduced deflections and bending moments of pile groups.Inspired by the results,a simplified design method,the pile-raft connection coefficient Kc was proposed.Additionally,the pile-head restraint percentage was established to make a relationship with the pile-raft connection coefficient in order to assess the pile-raft connection and guide the pile-raft design.In this paper,the recommended range value of Kc is 10–200 and the range value of pile-head restraint percentage is 24%–42%.展开更多
The paper summarizes the research on the development of standards for tunnels and roads LED lighiing application in Shanghai. analyzes the existing problems on LED road lamps and lighting design, introduces the experi...The paper summarizes the research on the development of standards for tunnels and roads LED lighiing application in Shanghai. analyzes the existing problems on LED road lamps and lighting design, introduces the experiments and testing results, and summarizes current problems of LED street lighting, proposing that LED lighting energy conservation should he ＂systematic energy saving＂ throughout the full life cycle based on the integration of products and applications.展开更多
By using the linear combination of bulk band （LCBB） method incorporated with the top of the barrier splitting （TBS） model, we present a comprehensive study on the quantum confinement effects and the source-to-drai...By using the linear combination of bulk band （LCBB） method incorporated with the top of the barrier splitting （TBS） model, we present a comprehensive study on the quantum confinement effects and the source-to-drain tunneling in the ultra-scaled double-gate （DG） metal-oxide semiconductor field-effect transistors （MOSFETs）. A critical body thickness value of 5 nm is found, below which severe valley splittings among different X valleys for the occupied charge density and the current contributions occur in ultra-thin silicon body structures. It is also found that the tunneling current could be nearly 100% with an ultra-scaled channel length. Different from the previous simulation results, it is found that the source-to-drain tunneling could be effectively suppressed in the ultra-thin body thickness （2.0 nm and below） by the quantum confinement and the tunneling could be suppressed down to below 5% when the channel length approaches 16 nm regardless of the body thickness.展开更多
To study the mechanical responses of large cross-section tunnel reinforced by pretensioned rock bolts and anchor cables, an analytical model is proposed. Considering the interaction between rock mass and bolt-cable su...To study the mechanical responses of large cross-section tunnel reinforced by pretensioned rock bolts and anchor cables, an analytical model is proposed. Considering the interaction between rock mass and bolt-cable support, the strain softening characteristic of rock mass, the elastic-plastic characteristic of bolt-cable support, and the delay effect of installation are considered in the model. To solve the different mechanical cases of tunneling reinforced by bolt-cable support, an analytical approach has been put forward to get the solutions of stress and displacement associated with tunneling. The proposed analytical model is verified by numerical simulation. Moreover, parametric analysis is performed to study the effects of pretension force,cross-section area, length, and supporting density of bolt-cable support on tunnel reinforcement, which can provide references for determining these parameters in tunnel design. Based on the analytical model, a new Ground Response Curve(GRC)considering the reinforcement of bolt-cable support is obtained, which shows the pretension forces and the timely installation are important in bolt-cable support. In addition, the proposed model is applied to the analysis of the Great Wall Station Tunnel, a high-speed railway tunnel with a super large cross-section, which shows that the analytical model of bolt-cable support was a useful tool for preliminary design of large cross-section tunnel.展开更多
文摘Given the increasingly notable segmentation of underground space by existing subway tunnels, it is dif- ficult to effectively and adequately develop and utilize underground space in busy parts of a city. This study presents a combined construction technology that has been developed for use in underground spaces; it includes a deformation buffer layer, a special grouting technique, jump excavation by compart- ment, back-pressure portal frame technology, a reinforcement technique, and the technology of a steel portioning drum or plate. These technologies have been successfully used in practical engineering. The combined construction technology presented in this paper provides a new method of solving key techni- cal problems in underground spaces in effectively used cross-subway tunnels. As this technology has achieved significant economic and social benefits, it has valuable future applications.
文摘Carpal tunnel syndrome (CTS) is the most common of all focal neuropathies. Electrodiagnostic (EXD) of CTS has advanced to include Combined Sensory Indexes (CSI) improving the specificity and sensitivity of EXD by employing intra-hand comparative data. Ultrasound (US) is a popular tool for the assessment of CTS. Cross Sectional Area (CSA) is the most consistent US parameter, but as a single test, it has a similar false negative profile to EXD. This study describes a dual method of CTS interrogation by EXD and US with the results applied to a single numerical score;the Combined Median Score (CMS). This is the product of CSA of median nerve at Carpal Tunnel inlet and CSI. In a series of 100 suspected cases, standard EDX identified 89 positive cases, CSI identified 92 positives, CMS identified 95 positives. This new method further reduced the false negative rate in CTS.
基金funded by the National Natural Science Foundation of China(Grant No.51878157,52308341)the Natural Science Foundation of Jiangsu Province(Grant No.BK20181282)the China Scholarship Council(CSC202106090083).
文摘The lateral response of combined pile-raft foundations(CPRFs)adjacent to tunnel excavation is a challenging problem owing to the complexity of the pile-raft connections.In current engineering practices,the impact of these connections on the lateral performance of CPRFs is frequently overlooked,despite their importance.To address this issue,this study conducted three-dimensional finite element analyses to evaluate the contribution of pile-raft connections to the tunnelling-induced lateral performance of CPRFs in saturated clay.In the analysis,both passive and active loading at the pile head could be considered by varying the tunnel depth.Several parameter studies,such as relative pile-raft modulus,pile embedded modulus,pile embedded depths,and pile shaft skin friction,were conducted to determine the optimal design parameters for CPRFs.The results indicate that pile-raft connections significantly affect the tunnellinginduced deflections and bending moments of pile groups.Inspired by the results,a simplified design method,the pile-raft connection coefficient Kc was proposed.Additionally,the pile-head restraint percentage was established to make a relationship with the pile-raft connection coefficient in order to assess the pile-raft connection and guide the pile-raft design.In this paper,the recommended range value of Kc is 10–200 and the range value of pile-head restraint percentage is 24%–42%.
文摘The paper summarizes the research on the development of standards for tunnels and roads LED lighiing application in Shanghai. analyzes the existing problems on LED road lamps and lighting design, introduces the experiments and testing results, and summarizes current problems of LED street lighting, proposing that LED lighting energy conservation should he ＂systematic energy saving＂ throughout the full life cycle based on the integration of products and applications.
基金supported by the National Basic Research Program of China (Grant No.G2009CB929300)the National Natural Science Foundation of China (Grant Nos.60821061 and 60776061)
文摘By using the linear combination of bulk band （LCBB） method incorporated with the top of the barrier splitting （TBS） model, we present a comprehensive study on the quantum confinement effects and the source-to-drain tunneling in the ultra-scaled double-gate （DG） metal-oxide semiconductor field-effect transistors （MOSFETs）. A critical body thickness value of 5 nm is found, below which severe valley splittings among different X valleys for the occupied charge density and the current contributions occur in ultra-thin silicon body structures. It is also found that the tunneling current could be nearly 100% with an ultra-scaled channel length. Different from the previous simulation results, it is found that the source-to-drain tunneling could be effectively suppressed in the ultra-thin body thickness （2.0 nm and below） by the quantum confinement and the tunneling could be suppressed down to below 5% when the channel length approaches 16 nm regardless of the body thickness.
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFC0805401)the National Natural Science Foundation of China (Grant No. 51738002)+1 种基金the China Railway Corporation Research and Development Program of Science and Technology (Grant No. 2014004-C)the Fundamental Research Funds for the Central Universities (Grant No. C17JB00030)。
文摘To study the mechanical responses of large cross-section tunnel reinforced by pretensioned rock bolts and anchor cables, an analytical model is proposed. Considering the interaction between rock mass and bolt-cable support, the strain softening characteristic of rock mass, the elastic-plastic characteristic of bolt-cable support, and the delay effect of installation are considered in the model. To solve the different mechanical cases of tunneling reinforced by bolt-cable support, an analytical approach has been put forward to get the solutions of stress and displacement associated with tunneling. The proposed analytical model is verified by numerical simulation. Moreover, parametric analysis is performed to study the effects of pretension force,cross-section area, length, and supporting density of bolt-cable support on tunnel reinforcement, which can provide references for determining these parameters in tunnel design. Based on the analytical model, a new Ground Response Curve(GRC)considering the reinforcement of bolt-cable support is obtained, which shows the pretension forces and the timely installation are important in bolt-cable support. In addition, the proposed model is applied to the analysis of the Great Wall Station Tunnel, a high-speed railway tunnel with a super large cross-section, which shows that the analytical model of bolt-cable support was a useful tool for preliminary design of large cross-section tunnel.
