| Tunnel engineering is the focus and difficulty of high-quality construction of high-speed railways in China.The topography and geological conditions in the western region of China are extremely complex and geological activities are frequent,making it difficult to accurately identify the geological conditions along the long tunnels,and the construction of railway tunnels through faulted and fractured zones faces huge risks.The traditional risk management is mainly focused on a single risk factor or risk event,which is no longer suitable for the current safety risk management of multiple risk events in railway tunnel construction in the western region of China.In this context,this paper focuses on the identification of safety risk factors,the evolution of multiple risks and their network analysis,risk assessment,risk control and other four aspects of the construction of railway tunnels through fault zones,and conducts in-depth research on the safety multiple risk management of railway tunnel construction through fault zones.The specific research content is as follows:(1)Identification and analysis of construction safety risk factors for railway tunnels crossing fault zones.Based on the risk assessment data collected from 32 railway tunnels crossing fault zones,a database of railway tunnel construction safety risk cases crossing fault zones was constructed;using the rooting theory,22 of the cases were used as the original data for open coding,spindle coding and selective coding,while the remaining 10 cases were used for theoretical saturation testing to identify the 10 major risk factors and 50 risk factor indicators were identified.(2)Multiple risk evolution and network analysis for railway tunnel construction safety across fault zones.Based on the logic of "risk evolution elements-multi-risk factor transmission-multi-risk factor superposition-risk event coupling " The logical idea is to analyze the risk evolution elements,multi-risk factor conduction and superposition,and multi-risk event coupling relationships for railway tunnel construction safety through fault-break zones.The key risk factors and key relationships of the network were identified.(3)Construction of a multiple risk assessment model for railway tunnel construction safety across fault zones.Through the core-edge analysis,point degree centrality analysis and intermediary centrality analysis in the social network analysis,the key influencing factors of the single risk event of railway tunnel construction safety through fault zone fracture zone were obtained,and the assessment index system of the four types of single risk events,namely landslide,water and mud burst,large deformation and surface water loss,was constructed respectively;based on the statistical data,the most likely simultaneous occurrence of landslide-water and mud burst dual The risk network and assessment index system were constructed based on statistical data for landslide-sudden mud and landslide-sudden mud and large deformation triple risk events;the entropy weighting method was applied to construct a matrix of key influencing factors to determine the index weights of key influencing factors for risk events,and the TOPSIS method was applied to construct assessment models for single risk of landslide,double risk of landslide-sudden mud and triple risk of landslide-sudden mud and large deformation.The risk possibility assessment level and damage assessment level are considered comprehensively.(4)Multiple risk management for railway tunnel construction through fault zones.Based on the characteristics and rules of multiple risk transmission,superposition and coupling of tunnel construction safety,multiple risk streams are taken as risk management objects,and the concept of "risk source interception" is proposed with the core of "containment of risk sources,risk control and risk reduction";The overall construction safety multiple risk management framework,consisting of risk source monitoring,risk data processing,risk early warning system and risk emergency response,has been constructed;the "containment of risk sources" measures based on the monitoring system,the "risk control" measures based on the early warning system and the "emergency response" measures based on the emergency response have been proposed.(5)An empirical study was conducted on the safety risk management of HQG tunnel construction through two fault zones.Based on the construction conditions and technical characteristics of the HQG tunnel,the key elements of the triple risk events of water and mud burst,large deformation and landslide and the possible losses caused by the superposition of risk factors were analyzed,and a safety risk network diagram was constructed for the HQG tunnel construction;the possibility and losses of the single risk of landslide,the double risk of landslide-water and mud burst and the triple risk of landslide-water and mud burst-large deformation were assessed.Based on the risk assessment level,the optimization of the HQG tunnel construction safety risk monitoring scheme,early warning treatment and emergency response measures are proposed,and the effectiveness of construction safety risk control is summarized.The innovation of this paper is: based on the perspective of multiple risks,the mechanism of multiple risk evolution for railway tunnel construction safety through fault and fracture zones is explored in depth,an assessment index system and assessment model of triple risk events for railway tunnel construction safety through fault and fracture zones are constructed,and an innovative system of multiple risk control for railway tunnel construction safety through fault and fracture zones is proposed based on the concept of "risk source interception".The study results will be useful for improving the safety of railway tunnels and the construction of railway tunnels in China.The research results are of great theoretical and practical value to improve the construction management of railway tunnels and underground projects in China.There are 48 figures,70 tables,and 157 references. |
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