盾构毕业论文英文摘要(2)

　ABSTRACT:In recent years, as the unceasing development of urban economic and theenlargement of construction scale, the transport resources become scarce and thetransport  problems  become  prominent.  Environment  problems  from  urbannon-point  source  pollution  have  greatly  confined  the  urban  economic  andsustainable development of our society. In order to alleviate the urban trafficcongestion and improve the urban transportation and environment, at the sametime  to  promote  the  sustainable  development  of  cities  and  the  coordinateddevelopment  between  urban  and  rural  areas,  the  development  of  urbanunderground Space is an important content of modern urban construction andmanagement. Shield tunnel is an attractive excavation method in the constructionof municipal underground engineering. Along with the rapid development of shieldtunneling, the geologic and hydrologic conditions are usually very complex, thestability  of excavation  face  is very  difficult to  forecast  and  control  duringconstruction stage. It is easily causing disasters, such as surface subsidence, waterinrush accidents. According to incomplete statistics, in the construction of subwayshield tunnel the instability of shield-tunneling faces have sometimes taken placefor recent years to make heavy losses of economy and calamities of injuries anddeaths in Beijing, Shanghai, guangzhou, nanjing, shenzhen and other major citiesof China. For the complicated environmental conditions, formation sensitivity andthe strict control standards, the stability of excavation face is a key problem toshield tunnel construction technology.

　　In this paper, earth pressure balanced （EPB） shield tunneling projects as themain object of study. Studied the instability mechanism of shield一tunneling faces,disaster evolution characteristics of instability of shield一tunneling faces underseepage  action  and  its  control  technology  system  of instability  in  depth  bylaboratory experiment, theoretical analysis, numerical calculation, model test andfield  test.  The  result  has  theoretical  significance  and  practical  value  in engineering project, mainly includes:

　　（1）Summarized  and  proposed  the  construction  method  and  equipmentselecting.  The  equipment  selecting  suitability  obtains  from  the  permeabilitycoefficient of formation, grain composition, characteristics of geotechnical andgroundwater state. Developed the software system which had a good man一machineinterface with shield construction method. The rules to select the shield methodunder complex geological environment especially the water一rich sand stratum isconducted in一depth study.

　　（2） By sorting and analyzing the cases of surface subsidence and water inrush,caused by excavation surface instability, the disaster environment and evokedfactor are analyzed. The basic characteristics of disaster sources were introducedin the paper. And set up a system of evaluation indexes of excavation surfaceinstability. The attribute recognition model is established. It provided a dynamicassessment of the high risk period of tunnel based on the software system. Putforward the prevention and control measures of excavation surface instability byearth pressure balance shield construction.

　　（3） Based on the limit analysis upper limit theorem, the 3D revolving bodydamage model is built. The formula of ultimate supporting force of excavationface is derived by the critical failure power of doing work by external forces isequal to the internal dissipation of soil.The critical failure supporting force ofexcavation face in homogeneous formation and complex strata is solved by thecomputer program. The computer program is compiled by MATLAB.For complexstrata, this paper respectively analyzed the influence factors such as tunnel depth,characteristics of soil, groundwater level under two working cases. They are thecasing soil and crossing layer. Compared with the calculated results with thepredecessor's results, it verify that the validity of the theoretical model.

　　（4）  Based  on  the  3D  revolving  body  damage  model,  introduced  thegroundwater seepage action to the limit analysis of excavation face stability. Thenthe seepage force formula deductions of collapse of the soil and excavation faceare demonstrated. The relationship between seepage force and groundwater levelwas obtained. The upper limit solution of supporting force of excavation face under complex strata was finally solved.

　　（5） The construction mechanics process of earth pressure balance shield undercomplex  strata  is  calculated  by  numerical  method  considering  the  effect  ofgroundwater seepage. The relationship between the damage forms of excavationface, deformation of excavation face, surface deformation, limit supporting forceand tunnel buried depth, mechanical properties of rock and soil, groundwater stateare studied in the paper respectively earth pressure balance shield constructionunder homogeneous formation and complex strata.

　　（6） In order to study the change rule of excavation face supporting force andfailure mode of shield tunnel excavation face under seepage force, then shieldtunneling construction model test system was developed. It includes visual testplatform, waterproof automated monitoring system. Take shield tunnel that crosslimestone and sand layer of Jinan Metro line R1 as engineering backgrounds, andcarry out model test about the excavation face stability in complex ground, tostudy the problem  for stability  of excavation  face  of  shield  construction  incomplex ground under different buried depth and water head height, analyzeinfluence law that buried depth and water head height affect ground settlement,limit  supporting  force  and  soil  deformation  of  excavation  fare,  reveal  theevolutionary mechanism about excavation face unstable failure.

　　Key  words:shield tunnel;  excavation  face  stability;  compound  strata;  limitanalysis; groundwater seepage; control measures.

　　盾构毕业论文英文摘要三：

　　论文题目：盾构隧道管片内力分布特性数值模拟分析

　　ABSTRACT: In recent years, a lot of tunnel projects were built in the world greatly promote thetechnology of shield tunnel, and the fixed methods are forming in most country about thedesign of shield tunnel segment structure. But there are no definite rules about the computingmodels or computing methods of load on deferent soil, so many numerical methods are springup about tunnel and underground project.

　　In this paper, taking a shield tunnel in Shenyang Metro as an example, three internalforce computing methods of shield tunnel are reviewed and analyzed. A new load-structuremodel of calculating the segment internal force is proposed based on earth pressurecalculation method in soil mechanics. Analyzing the factor of segment internal force, such asthe different joint type, tunnel depth, the diameter of segment, the elasticity modulus andPoisson's ratio of soil. The distributions of internal forces on segments are simulated by usingfinite element method while the ground stress release rates induced from shield tunneling areconsidered. The practical ground stress release rate of a tunnel is determined by comparingsettlements computed by finite element method with in-situ observed data. The numericalsimulation shows that the maximum settlement of ground surface is proportional to groundstress release rate. Based on plane assumption of beam in bending state in material mechanics,the analytical expressions of bending moment allocations on double-layer linings of shieldtunnel are deduced. Two examples for double-layer linings of shield tunnel are numericallysimulated with FEM in order to compute moment allocation ratio. Analytical solutions forallocation ratio of bending moments agree well with numerically simulations. Analyzing therelationship between the first lining and second lining; Analyzing the influence of internalforce on shield tunnel segment by soil relaxation pressure on the example subsea tunnel ofQIONGZHOU strait with high water pressure and great depth.

　　Key Words: Shield Tunnel segment; internal forces; ground stress release ratedouble-layer linings; soil relaxation pressure.