Key Technology Of EPB Shield Construction In Metro Tunnel And Its Application In Engineering

Earth pressure balance shield machine(EPB shield machine)after 60 years of development and growth,with its unique advantage has been widely used in subway tunnel engineering all over the world.As the design of urban rail transit network construction in the form row,the characteristics of the construction and key technology of shield construction,ground settlement caused by shield tunneling construction is very common phenomenon,how to protect the safety of shield construction,adjacent buildings and control the surface deformation become shield construction technical problems must be solved.As a country with a relatively late development of underground construction engineering,Vietnam has very little research on shield tunnel construction technology,especially urban subway shield tunnel construction technology,and there is very little research on its theoretical analysis and practical application.Therefore,as a Vietnamese international student majoring in underground construction engineering,it is necessary to conduct a systematic research on the earth pressure balance shield machine in underground construction engineering in Vietnam based on its own professional knowledge level and actual national engineering problems.This research is not only huge The social and economic value of the country,and good development prospects.Based on the construction project of Ho Chi Minh Metro Line 1,this thesis analyzes and studies the surface settlement and control measures caused by earth pressure balance shield construction.The main research contents are as follows:(1)The key technology of shield construction and ground settlement caused by shield construction method is summarized,the researches of analysis of domestic and foreign research present situation,development trend and the main problems.This paper introduces the origin of earth pressure balanced shield construction machine,the scope of its application in underground engineering,the development situation and trend,and further clarifying,and then discusses the earth pressure balanced shield machine working principle including tunneling,displacement,and the segment installation work;Earth pressure balanced shield machine typical structure and selection of main basis and factors.The key technology and common problems in the construction of earth pressure balance shield machine are briefly described,including:the construction technology of shield starting,formal driving and reaching three stages;The design of the tunnel lining segment principle,production pattern and assembly technology;Monitoring and measurement technology in construction;Shield construction of common problems and solutions,etc.,for expansion of the follow-up research work for sook.(2)The system studied surface subsidence mechanism by earth pressure balance shield construction process caused,the effect of time and space,subsidence curve principle,shield construction is analyzed and the ground settlement and the main reason causing formation,some meaningful conclusions are drawn.(3)The field observation of surface settlement caused by shield construction is analyzed,the purpose of monitoring work and the basis for the formulation of monitoring scheme are analyzed,and the monitoring content and scope of this project are proposed.The numerical simulation model of surface settlement caused by shield construction is established.In view of the actual engineering situation,the influence of shield construction on the surrounding soil is analyzed by using the experience analogy prediction method,and the characteristics,scope,development process and estimation method of the influence are put forward.Based on the conclusion of analogical prediction of similar engineering experience,numerical simulation prediction and analysis of calculation results of field monitoring,the law of surface deformation caused by dynamic tunneling is put forward.(4)Analyzes the ground settlement caused by shield construction control measures: grouting speed and time of operation,the determination of shield machine and the parameters of the excavation,reduce and prevent formation of disturbance,and strengthen the shield tail void sinking and the burial depth of the tunnel control,strengthen the monitoring of underwater level,reduce the surface load,driving direction control,segment installation control,etc.The above measures are summarized,the control measures are put forward preliminarily,and the protection measures in shield construction are formulated.(5)Analyzes the case of this project: Engineering environment,engineering geological and hydrogeological,engineering characteristics and engineering construction difficulties and construction organization and management,the shield machine before inspection,the experimental section,the parameters,the formal excavation control,emergency treatment measures,etc.,in the process of using Plaxis3 D Tunnel numerical simulation software simulation,simulation calculation according to the actual construction process,The deformation law of ground surface caused by dynamic tunneling is analyzed and compared with the measured data of engineering cases.At the same time,the application effect of EPB shield machine in Vietnam metro tunnel engineering is systematically studied,and the research results of guiding significance for practical engineering design and construction are obtained,which can provide reference for similar projects in the future.Finally,the application effect of EPB shield machine in metro construction engineering is evaluated,and the applicability and economic benefits of EPB shield machine in Vietnam metro tunnel engineering are verified.Based on the working principle of EPB shield construction,this thesis summarizes the shield construction method,studies the key technology of EPB shield construction and the mechanism of surface settlement caused by shield construction,as well as the main causes of ground changes and surface settlement caused by shield construction,and studies and proposes the control technical measures of surface settlement caused by EPB shield construction.Multiple factors affecting surface settlement are analyzed by using 3D finite element software Plaxis 3D Tunnel,and the engineering application of EPB shield is studied in combination with Ho Chi Minh Metro Line 1 project in Vietnam.The main conclusions are as follows:(1)Earth pressure balance shield is characterized by wide adaptability to the formation,safe operation,fast tunneling speed,small impact on the environment,low engineering cost and expensive equipment,so a shield machine is often applied twice or repeatedly in different sections.The paper proposes that the application scope of subway tunnel engineering is combined with the development situation and trend of EPB shield to meet the needs of projects in different fields,and at the same time,the basis for understanding the principle of EPB shield tunneling,the construction of shield mechanism and the selection of shield.(2)The thesis briefly describes the key construction technology of EPB shield machine,finds out the most common problems in shield construction,and then proposes solutions to ensure the safety and quality of shield construction,providing reference for subsequent research work.(3)This thesis systematically studies the five stages of surface settlement caused by shield tunnel construction,which are pre-settlement,settlement before excavation,settlement during passage,settlement after shield tail(shield tail clearance)and subsequent settlement(subsequent consolidation settlement).Again combined with engineering case collection and practical observation results comparing with the results,the budget,the result shows that the project settlement of cross-sectional curve with theoretical curve Peck formula are basically identical.(4)For the control measures of surface settlement caused by EPB shield construction of subway tunnel,this thesis analyzes and discusses the problems of surface settlement caused by EPB shield construction,and puts forward the corresponding main control measures,which provides a reference for future engineering practice.(5)According to the specific situation of shield construction of Ho Chi Minh Metro Line 1,various parameter models in the process of EPB shield tunneling construction are established,and the transverse deformation results of ground surface caused by the excavation of the eastern line of Ho Chi Minh Metro Line 1 are analyzed.The results show that: The results of numerical simulation are very consistent with the field measured data,and there is little difference in the overall surface deformation trend and behavior,which indicates that the numerical simulation is reliable under the same construction parameters.Therefore,the Plaxis 3D Tunnel program is used to simulate the ground settlement caused by EPB shield Tunnel construction.If the input parameters are accurate,the calculated results are reliable.At the same time,the larger the buried depth of the tunnel(H/D?3),the smaller the settlement value caused by shield construction,the more stable the surface,and the construction will be safer.With the theme of "key technology of EPB shield construction in metro tunnel and its application in engineering",this thesis focuses on two key scientific issues: the key technology of EPB shield construction,its influence on surrounding soil and the surface settlement caused by the construction process.The comprehensive research methods such as "collecting and analyzing similar engineering examples","numerical simulation method","field measurement and demonstration" are applied to carry out comprehensive and systematic research,and paper main effects and prospects of this research are presented below:(1)In this thesis,the key technology and safety technology management of EPB shield construction,the prediction and control measures of surface settlement caused by the construction process are studied,so that enterprises not only understand the risks in the process of shield crossing,but also know how to improve the safe crossing of the project,and reduce the influence of earth pressure balance shield construction on the rock and soil mass structure.To effectively control construction cost and construction time limit for a project,improve the economic benefits of Vietnam ho chi minh city subway shield construction units and social benefits.(2)Earth pressure balance shield machine is a very advanced construction and production system,including shield body,cutter head and drive system,propulsion and hinged system,shield tail sealing system,screw conveyor and belt conveyor,segment lifting and assembly system,human brake and air pressure regulation system and a series of complex systems.In a specific engineering situation needs to provide the latest construction key technology and safety management guidance.In this thesis,the geological condition model,surface settlement observation model,rock and soil mass structure deformation model and EPB shield construction technical parameter model of Ho Chi Minh Metro Line 1 crossing section are studied comprehensively,which improves the technical level of EPB shield construction,enrichs the technical theory of EPB shield construction and the protection measures of adjacent buildings and surrounding soil deformation.(3)From the Asian Development Bank,the European Bank for Reconstruction and Development,China,Japan,France,Germany,South Korea,Italy,England and other foreign investment and help,In 2008,the construction of the urban rail transit network began in Vietnam Ha Noi City and Ho Chi Minh City.By 2017,the underground bidding section of Ho Chi Minh Metro Line 1 will be officially started.In2018,Ha Noi metro line 3 also formally started.Plan in the future,Ho Chi Minh City to build 8 subway tunnel,the total length of about 169 km,Ha Noi City to build 8subway tunnel,the total length of about 318 km.In particular,the conditions of Ha Noi City and Ho Chi Minh City,Vietnam,are cities along the river,and the application scope of EPB shield machine is particularly wide.In addition to the general scientific research significance.Selected as the subject study for a Ph D research topic,in addition to ordinary scientific research significance,also contains a special significance,research results will be applied in my homeland Vietnam subway tunnel project.