Research conclusions:(1)The Qinghai-Tibet Railway sand disaster mainly distributes in the river and lake along the railway line，serious development time is the annual November to May next year. (2)Sand material mainly comes from the loose surface particles and fluvial lacustrine sediments of grassland degradation.(3)On the basis of a large number of data analysis and laboratory test，put forward several prevention measures about sand disasters. According to the guiding principle of“the distance to stop，near the fixed，comprehensive protection"，put forward targeted prevention mode of river courser sand disaster, degraded grassland disaster and lakeshore sand disaster prevention mode. (4)The research results have been successfully applied to the Qinghai-Tibet Railway prevention of sand damage system and prevention of sand damage effect significantly , which gives a good benefit to the similar construction projects.

Research conclusions:(1)The seism response of SSI multilayer ground base isolation building is found different，which is much greater under hanging-wall than footwall ground motions if the PGA of earthquake is not scaled，but the result is the other way around if the PGA is scaled at 400 gal. (2)It is also found that under the ground motions with rupture forward directivity the seism responses is the greater followed by ground motion with fling-step，and the ground motions without pulses is the smallest.(3)The normal component of fault is greater than the parallel under which the seism response of SSI multilayer groundbase isolation building. (4)This paper provides the seismic response rules of mountain isolated building frame structure to near-fault ground motions，and also provides valuable reference to seismic design of mountain isolated building.

Research conclusions:(1)Comparing with roadbed bearing capacity，circular arc method is more unsafe used to check the embankment stability.(2)The lateral displacement of roadbed will increase sharply when the load on roadbed approaches or exceeds roadbed bearing capacity，and the existing settlement calculation methods are no longer applicable. The application condition of settlement calculation methods is that the requirement of roadbed bearing capacity is met. ( 3)In order to ensure the stability of the embankment and control the settlement of embankment，the roadbed bearing capacity should be checked in the design of subgrade.(4)Conclusions of this paper can provide a theoretical basis for the further improvement of subgrade design method.

Research conclusions:Except post-construction settlement of subgrade and the differential subsidence between subgrade and other structures， differential settlement of the embankment and large lateral deformation of supporting structure must be reduced for embankment constructed on the slope foundation for high speed railway. The results show that digging platform for slope foundation with less 1:1 .25 slope ratio，lateral restraint pile or sheet-pile wall，etc. used to restrict lateral deformation and increase the stability of slope foundation，composite ground adopted to enhance the strength and reduce settlement of ground，anchor pile and composite construction with pile and board structure used to reduce the up lateral deformation of pile，transition and little space of piles of composite ground adopted to resolve differential settlement. It is very practical to design of high-speed railway，especially constructed on slope foundation.

Research conclusions : The test results show:(1)The micro-pile with smaller water cement ratio and larger cement sand ratio，was performed better bond behavior and corrosion durability.(2)The stress distribution was optimized in order to reduce the large cracks by separated reinforcement by physical isolated method. This also improved the bearing capacity of micro-pile structure. (3)Based on the research，several suggestions of micro-pile corrosion durability were proposed，such as design working life, pile diameter and protective layer, and were recommended for design reference.

Research conclusions ; The total displacement of the wheel is mainly the elastic deformation of the foundation，under the action of exciting force which is irregularity，foundation stiffness has greater impact on wheel-rail displacement，stress， etc. The stress between wheel and rail can be reduced through selecting the rational foundation stiffness. By analyzing the effect of the train speed and the wheel weight on vertical displacement of wheel-rail，contact stress and acceleration，a reasonable foundation stiffness 600 MPa/m-1 000 MPa/m was proposed. The laws of this paper summed，which includes the influence of track irregularity on wheel-rail contact conditions，and the influence of the vehicle speed，wheel weight，and foundation stiffness on wheel-rail vibration，can provide reference for the design of the foundation and wheel-rail contact of high-speed trains.

Research conclusions:(1)The mechanical properties of CA mortar is affected obviously by strain rates.(2)The compressive strength，elastic modulus and peak strain will increase with the strain rates，and compressive strength of CA mortar is the most sensitive to the strain rate，and it can improve 2. 5 times with the strain rate ranging from 10-5s~10-2s-1.(3)The fundamental shapes of the stress-strain curves of CA mortar at different strain rates are similar to each other，a rational fraction of expression is proposed here to express the stress-stain relationship of CA mortar at different rates. (4)The comparison between theoretical and experimental results shows a very good agreement at different rates，the research results could provide experimental evidence for establishing the rate type constitutive model，and apply to the design of dynamic structures of slab track.

Research conclusions:(1)In winter, the track slabs are mostly in tension，and cracking damages lie in dummy joints; in summer, the track slabs are basically compressed，only the area under the slab bottom near the dummy joints is in tension locally.(2)The maximum stress in the track slab，CA mortar and the supporting layer decreases with the increase of time，while the vertical deformation increases with time increasing, and both stress and vertical defomation will be gradually stabilized in about twenty years.(3)In addition to the dummy joints ( joint seams)，the track slabs have no serious fatigue damage area, and the cracking damages development of dummy joints ( joint seams) would be stabilized in five years，eventually the cracking area ratio of each section will be approximately stable at about 0. 7. (4)This paper can provide the theory basis for the design，maintenance and repair of the CRTS II slab ballastless track structure on subgrade.

Research conclusions:(1)The framework and functional modules of HRC-MIS are presented according to the theory of design and maintenance of heavy-haul regional CWR. ( 2)By studying the type，management scope，observation cycle and record method of the data，the calculating method with correction factor for actual neutral temperature and the algorithm for track section load which is based on aggregated traffic pushback are presented.(3)By deeply discussing about the internal correlations among all kinds of data and their influence on the status of the railway，the methods for statistical comparison analysis considering both space and time are proposed.(4)A prediction algorithm for actual neutral temperature by using the General Dynamic Fuzzy Neural Network is presented. And the assistant decision methods including regular and real-time over-limit alarming，early warning and maintenance instruction are proposed. (5)The results of this paper are worth popularizing in other regional CWR on heavy-haul railway and have reference value for the research on the variation law and status evaluation of CWR.

Research conclusions:Based on the research on the pushing force and motion of main girder in process of Shangdi Bridge single cable plane curve of prestressed concrete cable-stayed bridge jacking on Beijing-Xinjiang Highway，it can reach the following conclusions:(1)Put forward a new method of the construction of complex curve of concrete box girder，by which it can simplify the design of the ramp and spacing device，and control pusher track of the complex curve girder. (2)Because two-point limit structure is statically determinate system in the horizontal plane，it can be calculated accurately the level of the working condition of the limit force pushing process. And the temporary pier horizontal reaction greatly reduced to the only 1 .2‰ of pushing weight，which provides the technical support for the construction security of weight of the complex curve girder pusher.(3)Tw。-point limit method is suitable for the complex curve prestressed concrete box girder bridge construction of roads，railways and municipal engineering which using the jacking method.

Research conclusions:(1)The stress calculated by computer space rigid model can be directly used to fatigue design， and need not to be corrected by structural factor. The problem faced by designer can be solved，which is that the results calculated by computer space rigid model cannot be used to fatigue design. (2) Through a lot of research，measurement and calculation，the typical operation train and fatigue load spectrum under the current transport situation are determined. It makes the fatigue design closely follow up the current transport situation.(3)Fatigue design partial coefficients are studied，and the fatigue limit state design methods of intercity railway，high speed railway and freight railway are established. It fills the blank of fatigue design in intercity railway, high speed railway and freight railway. (4) The typical steel bridge has been designed according to the fatigue design method based on the new situation，the design results show that the reserves of the fatigue design methods under the new situation compared with the existing fatigue allowable stress design method is increased slightly. Research results will be incorporated into “railway bridge design specifications(limit state design)”，and will be directly used to design the new steel bridges in future，and can provide a reference for fatigue assessment of existing railway steel bridge.

Research conclusions:For the problem of insufficient in a continuous steel truss girder bridge bearing capacity which can not be uninstalled, we select a variety of schemes and innovatively choose to increase the main truss reinforcement to solve this problem. To meet the old and new structures taking force together,、introduce the method of jacking-up of the new truss to converse the force system. After two years of actual inspection and analysis，the reinforcement scheme turns out to be safe and reasonable，reinforcement effect is satisfying. The new reinforcement scheme can be used to the similar engineering.

Research conclusions ; The monitoring data indicates that:(1)The initial support strength and supporting structure stiffness must increase correspondingly with the increase of inclined shaft depth and ground stresses，otherwise the tunnel is easy to collapse，and the method of using arch can effectively control the deformation during construction.(2)The current classification standard couldn’t be applied in large deformation of Lanzhou-Chongqing Railway Permian soft rock;it should be combined with the construction conditions to determine the corresponding supporting structure and construction measures. (3)The influence of high ground stress on the stability of rock mass should be combined with the engineering practice analysis，side wall and arch waist are the key parts of large deformation construction， construction parameters and supporting measures should be adjusted timely to ensure the smooth progress of the construction. (4)The results of study can provide guidance to the design and construction of Permian soft rock tunnel structure for future.

Research conclusions:(1)Established the evaluation grade of seismic damage of tunnel structure，mainly including the graded principles of the seismic damage degree of the tunnels，the evaluation grade of seismic damage of reinforced concrete and plain concrete secondary lining, and the treatment key point of seismic damage of the three stages，the first aid repair stage，ensure access stage，restoration and reconstruction stage.(2)Clarified the disposal technologies of seismic damage of tunnel lining structure of three stages，the first aid repair stage，ensure access stage，restoration and reconstruction stage.(3)The disaster area in Wenchuan earthquake used the evaluation grade of seismic damage and disposal technologies of tunnel structure for restoration and reconstruction after the earthquake，reached the goal of restoration and reconstruction，which recovered or over the level of operation and earthquake-resistant of the tunnels in the earthquake zone before earthquakes.(4)The research results can provide a reference for the repair of seismic damage of the tunnels in the earthquake zone and aseismic design of tunnel structure.

Research conclusions:For the research on the analysis of measured data of blasting vibration，some useful results can be concluded. Firstly, the maximum vibration velocity of Electronic Detonator Blasting(EDB ) is smaller than that of Millisecond Detonator Blasting(MDB )，and EDB has a relative short sustained time. Secondly，the wave of EDB is well-distributed and steady. The frequency coverage of EDB is wider and has multiple peaks, the high-frequency components of EDB are more abundant than that of MDB. The time-energy density curve of EDB does’t have the abrupt and separated fluctuation，which indicates the interference and superposition of EDB are very distinct. Moreover Electronic Detonator has high precision and good safety performance，and it can effectively improve the blasting effect and reduce the consumption of explosives. The controlled blasting and tunnel support measures of this project have achieved a good effect, which provide the valuable reference to the study on controlled blasting for shallow tunnels in urban areas.

Research conclusions:(1)The integral dropper with current carrying capacity should have the significant function distributing current with parallel many points，only the three-five droppers and one electrical connector near the current change point could take part in the current distribution of OCS，and the other droppers and the electrical connectors should hardly take part in the current distribution which currents should approach zero.(2)Because the cross section of the dropper is limited，the dropper at the continuous current change point cannot undertake the current flowing, where the electrical connector must be set.(3)The electrical connectors should be set as a practical setting principles at the connection joints among the power supply lines and OCS，insulated overlaps，non-insulated overlaps， the connection joints among OCSs of differential rail tracks, and the electrical connectors need not be set at the other parts of OCS. The principles should be applied to all types of the OCS in electric railways.

Research conclusions:(1)Urban rail transit power supply system which takes lightning overvoltage protection measures could reduce the breakage rate of OCS insulator after thorough flash-over in overvoltage，also reduce the tripping rate of substation in a lightning stroke，which could meet both the reliability requirement of tractive power supply system and safety requirement of operation. (2)Because the protection measures to the isolator are inadequate，lightning arrester could not prevent backward flashover tripping, severe accidents and damages occur.(3)OCS insulator has low lightning withstand level，it is a valid measure to install in parallel metal oxide arrester with gap to prevent insulator lightning stroke damage. (4)OCS steel mast shall be earthed and OCS shall be installed overhead earth wire and shall approach live conductor as possible as it can，but no need to lift. (5)The substation shall adopt corresponding measures to carry out overvoltage protection against lightning stroke.(6)The research result can be applied on urban mass transit rail aspect.

Research conclusions:In this paper, we studied the influence factors and the estimating model of the investment of railway-station buildings，and got the following conclusions:(1)Based on the collected data of railway-station buildings，the main factors were obtained. BPNN model was built with the main factors as the input vector. (2)Genetic algorithm was used to optimize the initial weight and bias of BPNN model, the precision and generalization ability of the model was better through the comparison. (3)The practicability of GA-BPNN model was verified with the example of a new project. (4) The research of this paper provided the references to the similar research and the investment control of the railway-station buildings.

Research conclusions:(1)The analysis of the core content of Vickrey theory and the bidding strategy shows that the Vickery theory can effectively solve the problem of dishonest bid under information asymmetry. (2)The application of Vickery's theory in project bidding, can avoid the problem of finite string, so it is more suitable for railway project. (3)Using Vickrey auction theory can make the railway project get cheaper, more high-quality builders.(4)The relevant price incentives can improve the contractor's profit accordingly，reduce the occurrence of corner-cutting phenomenon in a certain extent and ensure the railway engineering construction in a more healthy way. (5)The results can be used in bidding by construction departments of railway engineering and other construction engineering.

Research conclusions:(1)The anticipated governmental financial fund in future is the source of BT Mode repurchase payment，due to the financial fund is different from other financing resources and its actual sum is uncertain，that the repurchase risk is the most important problem in front of investors. (2)The risks are mainly reflected in four aspects that the repurchase consciousness of the government party is still undeveloped，the government party may deliberately postpone the repurchase action，the repurchase guarantee can’t be honored and the repurchase price is subject to final audit. (3)It should enhance legal argumentation，endeavor to obtain repurchase guarantee from government party，include sophisticated business clauses in contract and seek remedial measures which are the significant legal control means to fight against governmental repurchase risks. (4 ) The research conclusions can be applied in the management fields and repurchase of project investment and financing construction mode.