The complicated geological conditions and geological hazards are challenging problems during tunnel construction,which will cause great losses of life and property.Therefore,reliable prediction of geological defective...The complicated geological conditions and geological hazards are challenging problems during tunnel construction,which will cause great losses of life and property.Therefore,reliable prediction of geological defective features,such as faults,karst caves and groundwater,has important practical significances and theoretical values.In this paper,we presented the criteria for detecting typical geological anomalies using the tunnel seismic prediction（TSP） method.The ground penetrating radar（GPR） signal response to water-bearing structures was used for theoretical derivations.And the 3D tomography of the transient electromagnetic method（TEM） was used to develop an equivalent conductance method.Based on the improvement of a single prediction technique,we developed a technical system for reliable prediction of geological defective features by analyzing the advantages and disadvantages of all prediction methods.The procedure of the application of this system was introduced in detail.For prediction,the selection of prediction methods is an important and challenging work.The analytic hierarchy process（AHP） was developed for prediction optimization.We applied the newly developed prediction system to several important projects in China,including Hurongxi highway,Jinping II hydropower station,and Kiaochow Bay subsea tunnel.The case studies show that the geological defective features can be successfully detected with good precision and efficiency,and the prediction system is proved to be an effective means to minimize the risks of geological hazards during tunnel construction.展开更多
Virtual reality(VR)simulations are some of the alternative practice environments for safety education.Trainees gain experience under the most realistic conditions without being exposed to any real hazard.Virtual reali...Virtual reality(VR)simulations are some of the alternative practice environments for safety education.Trainees gain experience under the most realistic conditions without being exposed to any real hazard.Virtual reality also serves as a tool to expedite the decision-making process where quick decisions and actions are necessities for a safe operation.One example of such a situation in underground mines is the failure risks in a tunnel face after blasting.Ground support systems must be installed based on the stand-up time to ensure the safe access of personnel and equipment to the working area.Generally,a competent person inspects the area to identify risks and determines the required support systems.However,training of a competent person requires large amount of time and effort.This study presents virtual reality simulations developed for improving the assessment of the roof fall hazards and taking necessary measures for mitigating the risk related to roof fall.The virtual reality simulation involves decision-making tasks for a particular scenario in which participants can experience creating a safe working environment in a timely manner.First,they are asked to identify the potential hazard in a tunnel after blasting,namely,rock fall,wedge failure or groundwater inflow.If the hazard identification is successful,participants are requested to install rock bolts as a safety measure by selecting the bolt pattern(e.g.bolt length and spacing).Finally,participants evaluate the roof fall hazard by viewing displacements around the opening,before and after the support measures.This study illustrates the benefits of VR in safety training as well as enhancing the decision-making process to enhance safety.展开更多
This paper presents an effective means of analyzing the safety of a tunnel under dynamic loading in areas<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;"...This paper presents an effective means of analyzing the safety of a tunnel under dynamic loading in areas<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">with seismic records. A particular case of the railway tunnel in the earthquake-prone regions of the escarpment seismic zone of Ethiopia was the specific focus area of the research. Probabilistic seismic hazard analysis (PSHA) and deaggregation have been conducted to determine the design earthquake required as an input for the dynamic analysis. The PSHA</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">performed by considering the operating design earthquake with conservative assumptions of the local geological features resulted in a peak ground acceleration of 0.36. Two pairs of design earthquake have been obtained from the deaggregation process, which were used to filter acceleration time histories for the selected design earthquake from the ground motion database of Pacific Earthquake Engineering Research Center. Finally, full dynamic analyses of the tunnel have been performed by applying the scaled acceleration time histories corresponding to the structure in the specific site. It was demonstrated how to prove the stability of the tunnel located in difficult ground conditions by performing plane strain analyses with the possible minimum computational efforts.</span>展开更多
基金Supported by National Natural Science Foundation of China (50625927,50727904)the National Basic Research Program (973) of China (2007CB209407)Ministry of Communications’Scientific and Technological Program of Transportation Development in Western China(2009318000008)
文摘The complicated geological conditions and geological hazards are challenging problems during tunnel construction,which will cause great losses of life and property.Therefore,reliable prediction of geological defective features,such as faults,karst caves and groundwater,has important practical significances and theoretical values.In this paper,we presented the criteria for detecting typical geological anomalies using the tunnel seismic prediction（TSP） method.The ground penetrating radar（GPR） signal response to water-bearing structures was used for theoretical derivations.And the 3D tomography of the transient electromagnetic method（TEM） was used to develop an equivalent conductance method.Based on the improvement of a single prediction technique,we developed a technical system for reliable prediction of geological defective features by analyzing the advantages and disadvantages of all prediction methods.The procedure of the application of this system was introduced in detail.For prediction,the selection of prediction methods is an important and challenging work.The analytic hierarchy process（AHP） was developed for prediction optimization.We applied the newly developed prediction system to several important projects in China,including Hurongxi highway,Jinping II hydropower station,and Kiaochow Bay subsea tunnel.The case studies show that the geological defective features can be successfully detected with good precision and efficiency,and the prediction system is proved to be an effective means to minimize the risks of geological hazards during tunnel construction.
文摘Virtual reality(VR)simulations are some of the alternative practice environments for safety education.Trainees gain experience under the most realistic conditions without being exposed to any real hazard.Virtual reality also serves as a tool to expedite the decision-making process where quick decisions and actions are necessities for a safe operation.One example of such a situation in underground mines is the failure risks in a tunnel face after blasting.Ground support systems must be installed based on the stand-up time to ensure the safe access of personnel and equipment to the working area.Generally,a competent person inspects the area to identify risks and determines the required support systems.However,training of a competent person requires large amount of time and effort.This study presents virtual reality simulations developed for improving the assessment of the roof fall hazards and taking necessary measures for mitigating the risk related to roof fall.The virtual reality simulation involves decision-making tasks for a particular scenario in which participants can experience creating a safe working environment in a timely manner.First,they are asked to identify the potential hazard in a tunnel after blasting,namely,rock fall,wedge failure or groundwater inflow.If the hazard identification is successful,participants are requested to install rock bolts as a safety measure by selecting the bolt pattern(e.g.bolt length and spacing).Finally,participants evaluate the roof fall hazard by viewing displacements around the opening,before and after the support measures.This study illustrates the benefits of VR in safety training as well as enhancing the decision-making process to enhance safety.
文摘This paper presents an effective means of analyzing the safety of a tunnel under dynamic loading in areas<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">with seismic records. A particular case of the railway tunnel in the earthquake-prone regions of the escarpment seismic zone of Ethiopia was the specific focus area of the research. Probabilistic seismic hazard analysis (PSHA) and deaggregation have been conducted to determine the design earthquake required as an input for the dynamic analysis. The PSHA</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">performed by considering the operating design earthquake with conservative assumptions of the local geological features resulted in a peak ground acceleration of 0.36. Two pairs of design earthquake have been obtained from the deaggregation process, which were used to filter acceleration time histories for the selected design earthquake from the ground motion database of Pacific Earthquake Engineering Research Center. Finally, full dynamic analyses of the tunnel have been performed by applying the scaled acceleration time histories corresponding to the structure in the specific site. It was demonstrated how to prove the stability of the tunnel located in difficult ground conditions by performing plane strain analyses with the possible minimum computational efforts.</span>
