Research conclusions:The maximum dynamic stress of bridge － subgrade transition section appeared in the turn corner of the trapezoidal bottom of the transition section with the average value of 12.73 kPa．After the surface of the foundation bed of the transition section was reinforced by the graded broken stone，the dynamic stress of transition section in the vertical reduced quickly and the attenuation rate was up to 90% on the bottom of the subgrade bed．The dynamic stress of the bed surface in the transition section increased by about 20% when the train speed increased from 200 km /h to 250 km /h，and the dynamic stress of the bed surface increased by about 10% when the train speed increased from 250 km /h to 350 km /h．

Research conclusions:The using of the existing interchanges，the influence of the metro colineation and the reduction of demolition should be taken as the primary dominating factors for the overall design of this project． Combined with the change of the road function，the double － plate form should be used for the cross － sectional of the road． Based on making full use of the higher standard of the existing road，the plane line position should be designed flexibly． The filling and excavation heights of the vertical section should be controlled strictly to converge with the surrounding environment． Combined with perfecting of the surrounding road network，the function and service levels of the interchange should be determined reasonably，and the reconstruction of the interchanges should be optimized．

Research conclusions:The topographical and geological conditions along the Chengdu － Lanzhou Railway are very complex because of the active faults，high intensity earthquake，landslide，collapse，strewn at random，talus，dangerous rockfall，debris flow and goaf and they may be the control elements for the railway alignment． So the following principles should be followed in the railway alignment: The railway should pass the active fault with short distance and big angle by adopting the simple engineering，and for the area along the active fault，the railway should be built on the lower wall (passive wall) and kept away from the the fault as far as possible，and the railway should pass round the unfavorable geological area where the geological conditions are complex and centrally distributed and it is difficult to treat them． Also the railway should pass round the big goaf． The west line scheme，the Jushuichang scheme and the scheme of the long tunnel on the left of the Min River with better geological condition are chosen．

Research conclusions:The mountain summit area is generally featured with the complicated stratum，the development of unfavorable geology and concentration of the regional geological structure． The railway alignment in this area is limited by the geological condition． Before determination of the alignment，the reconnaissance survey should be done in large range for the area where the railway probably passes in order to know the distribution and development situations of the stratum，the unfavorable geological conditions and regional geological structure，and the comparison should be made for optional plans in technology and economics． By doing these works，the railway can keep away from the special stratum，unfavorable geological area and big fault zone to improve the engineering geological condition and technical condition of the large tunnel in mountain summit area．

Research conclusions:In a certain environment，the mechanical properties of the tertiary mudstone with gypsum rock in Xining have the different characteristics． In the natural state，it has good engineering property，but after being immersed into water and exposed to the air for long time，it easily swells，corrodes，softens and disintegrates，resulting in reduction of its intensity and basic bearing capacity and making the environmental water corrosive．The engineering measures should be taken for its expansion characteristics in building railway embankment，cutting and tunnel and in building bridge and construction of the pile foundation of building，the attention should be paid to the environmental water corrosion to the reinforced concrete caused by mudstone with gypsum rock dissolution．

Research conclusions:The purpose of revising the " Code for Engineering Structure of Railway Subgrade" is to quantify the reliability of engineering structures．The compiling process of the code with the reliability theory can be summarized as follows: establishment of the limit state equation － giving the statistical characteristics of random variables parameters －calculation of the current standard implicit reliability index － determination of the target reliability index － putting forward the subitem coefficient － establishment of the limit state design expression．

Research conclusions:Taking the interchange overpass of Xibaipuo highway project as an example，the excavation process of the pile cap was simulated by using ABAQUS general finite element software and the displacement of the existed railway bridge foundation induced by foundation pit excavation was analyzed to find out the displacement of the adjacent railway bridge foundation caused by the construction of fender pile and excavation of the foundation pit．The analysis results showed that the foundation pit excavation had tiny influence on the existed railway bridge and the maximum displacement of the railway foundation was less than 2 mm． The design of fender pile met the demands of the railway operation safety．

Research conclusions:The numerical results show using the multiple － aperture saturated medium to simulate the saturated soil foundation can more accurately analyze the vibration response induced by the high － speed train，enhancing the track stiffness can effectively control the rail displacement and increasing the thickness of the foundation bed in design can reduce the impact of the liquid phase medium in soil on the dynamic response to the soil．

Research conclusions:Taking the Wuhan － Guabgzhou Passenger Dedicated Line as the engineering background，the different calculation methods for the tensile force of the geogrid were summarized． The plane finite element analysis model was established． The variation laws of the subgrade settlement，the load on the geogrid and the pile － soil stress ratio in process of subgrade filling were analyzed on consideration of the different geogrid modulus conditions．After the soil filling to a certain height，the increases of subgrade settlement，the load on the geogrid and pile － soil stress ratio became slow． The increase of geogrid modulus led to the obvious increase of the load on the geogrid． The use of reinforced cushion could effectively solve the problem of thestress concentration on the pile top problems and control the subgrade settlement．

Research conclusions:The horizontal natural vibration period cycle was controlled because of the large span and narrow width of the beam＇s box． Based on the analysis of the parameters，the analysis of the influences of the pier width，the box width of the beam，the slope of the pier and the horizontal layout of pile foundation on the natural vibration period of the structure were analyzed comprehensively． The double wall piers with the longitudinal straight slope and variation of lateral slope were designed to make sure the structure had enough lateral rigidity while the longitudinal stiffness of the could be reduced effectively，the requirement of load bearing for the large span continuous structure could be met，the transverse joint in double － wall piers could be cancelled and the structure could be of more lightweight with good looking appearance． In beam design，the layout of longitudinal prestressed steel strand was optimized ，the upwardly curved steel strand in the web was cancelled，the principal tensile stress was overcome by the longitudinal steel strand and the vertical prestressed steel to avoid the crack of the web of large span structure．

Research conclusions:(1) As the maximum relative longitudinal displacement of adjacent pier on the arch bridge occurs between the junction pier and G1 or G12 pier．(2) The movable abutment with large longitudinally displacement and expansion device should be used for the first beam at arch foot and the measures for prevention of span collapse should be taken．(3) As the pier top displacement of large － span arch bridge has big effect on the CWR track，the fastening with small resistance should be used for the CWR track on bridge to adapt the pier deformation．

Research conclusions:(1) On consideration of the structure on the arch，the minimum eigenvalue buckling in the analysis result was 13.477，and the eigenvalue buckling of the bare arch in the analysis result was 6.663．Both of them were bigger than 4 and 5 stipulated in the specification．The arch rib met the requirements of the stability inside and outside of the cross － section．(2) The minimum ultimate bearing capacity of the arch bridge in the analysis result was 2.252，and it showed that under the influences of the double nonlinearities and the initial defects of the structure，the safety factor of the bridge under main working conditions was 2.252，meeting the requirements of no less than 2 for the elastic － plastic stability safety factor on consideration of the nonlinear effects of the structure，and the structural design was reasonable．(3) The structures on the arch like the pier columns had the big effect on the stiffness of the bridge，while they had small impact on the ultimate bearing capacity of the arch．(4) The eigenvalue buckling in the analysis result was of a nonconservative calculation result． In the actual process of designing an arch bridge，the influences of the double nonlinearity and initial defects of the structure on the ultimate bearing capacity had to be considered． And the methods introduced in this paper could be as the reference to the similar works．

Research conclusions:From the analysis of the load bearing and deformation of key parts of the tunnel structure system during the excavation，it is concluded: (1) During excavation，the stress and deformation of the key positions of the left and right caverns and on the top of the middle partition wall follow the change regulation of the construction process．(2) The three bench of the middle pilot tunnel + right pilot tunnel + left tunnel is available for construction of such kind tunnel．(3) The unbalance support system should be used for the large span unsymmetrical multi － arch tunnel．(4) In order to solve the problem of water leakage on the top of the middle partition wall，the small pilot pipe should be installed and grouting should be conducted in the V area on its top． The rock on the top of the middle partition wall should be reinforced to improve its impermeability． The calculation result provides the reliable basis for the tunnel design and the reference to the similar works．

Research conclusions:From the analyse of the characteristic values of the elastic boundary，it is seen the fundamental vibration mode period of the model is 0.203 603 s．From analysis of the dynamic time － history of the elastic － plastic boundary，the velocity and acceletation before and after the building the vibration isolation belt are seen． The research result shows that the vertical vibration velocity is reduced by 39 percent in average，and the vertical acceleration is reduced by 38 percent in average when the vibration isolation belt isbuilt．

Research conclusions:In this paper，from the comparative analysis of two suspension and fixed modes of embedded spout and post － position anchor bolt from the areas of the load bearing situation，component properties，influence on tunnel，construction cost，construction methods，operation and maintenance，it is concluded: (1) The embedded spout has the advantages of the even load bearing，easy construction in later stage and reliable earthing，but with the high construction cost and the poor reservation accuracy of the pre － station construction．(2) The chemical anchor bolt has advantages of the no limitation of template，flexible positioning，controllable construction accuracy and low construction cost，but needing the additional earthing terminal with small adjustment allowance．(3) Based on the construction situation in China，it is recommended to give priority to using the suspension and fixed mode of post － position anchor bolt

Research conclusions:To reduce the interference on the transportation and the work volume，it is recommended to increase insulation and substitute four insulation joints for some five span insulation joints to make the length of the zone without power longer than 220m for meeting the demand of running the double EMUs． The solution is also presented on upgrading of the outlet phase splitting of the single phase wiring form transformer in order to enhance the operation reliablity．

Research conclusions:In the loading and unloading zone of the special railway line，the first terminal，the end terminal and the middle part of the crane tubes should be connected with the railway rails on both sides with the flat steel． The equalizing voltage devices should be installed for the equipotent connection and earthing． Two groups of rail insulation and the grounding device with the grounding resistance of no more than 10ohm should be installed for the special railway line． With combination of the practical experience of electrification upgrading design of the Guangdong section of the Beijing － Kowloon Railway，the electromagnetic protection measures are illustrated to provide the reference to the similar works．

Research conclusions:(1) The wind load pressure figuration coefficients of the No － platform － column Canopy is between 0.1 ～ 0.9，the wind load suck figuration coefficients is between － 0.3 ～ － 2.0; (2) The wind load pressure figuration coefficients of the test is smaller to the " Load Code for the Design of Building Structures" ( GB 50009 － 2001)and the wind load suck figuration coefficients is bigger; (3) The wind load figuration coefficients enlarges on the cornice and hole．

Research conclusions:Through the analysis of the advantages and disadvantages of the water lowering in and out of the foundation pit in strong permeability soil，the water lowering out of the foundation pit has the following features: (1) The requirement of water lowering can be met for the foundation pit with large water － bursting so that the works above the bottom surface can be done without water．(2) The interference and impact on the construction can be effectively avoided and cut so that it is good for the excavation of the foundation pit and organization and implement of the structure construction．(3) It is good for doing the works of the water lowering and drainage in order．(4) The station construction in later stage proves the prediction of the water － bursting volume of the foundation pit and calculation of the water yield of one well are accurate so that it can provide the reference to the similar works．

Research conclusions:It is proposed the " The General Estimate Compiling Method for the National Railway" and " The Railway Quota" should be used for compiling the general estimate of the urban railway except the station along with the" The General Estimate Compiling Method for the Intercity Railway" and " The General Estimate Compiling Method for Municipal Facilities" while " The General Estimate Compiling Method for Municipal Facilities" and " The Municipal Quota" should be used for compiling the general estimate of the station．

Research conclusions:In order to well do the survey and design works of the overseas projects and make full use of the good chance for going out，the Chinese enterprise should well know the background，the relative basic information and the function orientation of the international projects，reasonably work out the the technical standard and engineering measures，effectively control the project investment，improve the capacity，strengthen to build the market business and technical talents and well know the relative international and local codes and standards．Also the Chinese enterprise can coordinate with the famous consulting enterprise in the world if necessary．