Research conclusions: The introduction of the concept of " Loose Soft Soil" in the loess investigation，has made a supplement and improvement for“Code for Geology Investigation of Railway Engineering”． At home and abroad for the first time using the embedded consecutive pile － sheet subgrade structure，to solve the long － term creep resistance of the thick layer of clay soil under the subgrade base which would cause the settlement of subgrade． Comprehensively and systematically put forward the design principles and construction method of the large section of loess tunnel which is safely，rapid and economical． In the high － intensity earthquake zone and on the long continuous － beam bridge，the technology of four sets two － way rail expansion joint were used． In the north Weinan station，integrated design technology of pass － type station bridge and gapless turnout group was applied． These innovative technologies are the key to the technology package of civil works for high － speed railway built in collapsible loess regions．

Research conclusions: The model is based on the ellipsoidal coordinate system without consideration of the project deformation in adjustment，and it can directly and synchronously process the independent and original observational data by 3D adjustment processing and be available for the network of any size． Besides，with this function model，it is more conducive to conduct the combined adjustment with the GPS values and terrestrial observation values，and it can directly do the statistical test to the original observation values in the adjustment．

Research conclusions: From the research on design of the ballastless track and seamless track on the large span concrete bridge and the investigation of service situation of the existent seamless track on the large concrete bridge，the following points can be concluded: ( 1) If the track temperature span of large concrete bridge with the ballstless track exceeds the certain range，the disease will happen to the track structure． ( 2) The maximum longitudinal additional force of the rail and the load on the track structure can be reduced by cutting the longitudinal resistance of the rail fastening on the bridge by using the fastening with small resistance on the bridge． ( 3) The loads on the rail and the bridge pier and the deformation of the bridge structure increase obviously with the increase of the temperature difference of the bridge．( 4) The monitoring of the seamless track on the large span bridge and the experimental research on the design parameters of the seamless track have to be strengthened．

Research conclusions: The comprehensive geophysical exploration patterns for the bridge with high pier and big span under complex geological condition are as follows: ( 1) The comprehensive geophysical exploration is conducted with the three levels of the exploration precision． ( 2) The selected geophysical methods include the audio magnetotelluric method ( CSAMT or AMT) ，shallow seismic reflection wave method，DC electric sounding or high density resistivity method，tomography on cross － hole elasticl wave method，tomography on cross － hole electromagnetic wave method and single －hole well logging method． ( 3) The attention should be paid to the location survey stage and the main pier position of the recommended plan．

Research conclusions: The normal stress in top and bottom slabs of the girders and the shear force in weds could meet the relevant requirements in the codes． After adding the viscous dampers on the No． 38 and No． 40 piers，the structure could meet the seismic requirements． The main bridge structure had good dynamics with good traveling capacity for the train and it could meet the demands of the train running safety and passenger comfortableness．

Research conclusions: The stress of curved trough girder indicates obvious spatial character． The tesion endured by the lower flange of outside main girder of curve is large，while the inside main girder of curve is relatively small under vertical load． The shear lag in slab is remarkable． The non － uniform settlement 10mm has little effect on the girder force． With the gradual increase of vertical load on the top，the inward lateral displacement which occurs to the top flange of main girder becomes lager and lager，and the notch of trough girder truns smaller and smaller． The bending －torsion coupling effect causes the different support reaction of trough girder between the inner side and the outer side of curve，the support pressure of outer side of curve is greater than those of inner side of curve at beam end． The girder has a tendency of whole transverse deflection towards the inner side of curve．

Research conclusions: Under the effect of the axial compressive loading，the loads beared by the shear connector and the core concrete are proportional to their stiffness． The simulation calculation of the steel － concrete segment should be made according to the different simulation calculation purposes，and by using different models，such as the spring model，the solid model without bond － slip effects and the solid model on considering the failure of concrete with bond －slip effects． This paper presents a novel method for the connection between concrete beam and steel beam， that is to anchor the longitudinal steel bars directly on the end of the bearing plate without the joint segment． This connection structure is simple with the clear load bearing．

Research conclusions: By research and optimization of the construction plan， the requirements of the construction safety，rationality and operability were met to make the construction going ahead smoothly and safely． For construction of new －type bridge structure，it was necessary to analyze the characteristics of the bridge structure and optimize the construction plan before construction． The characteristics of the bridge structure could be better understood by doing research on the optimization of the construction plan before construction． In this way，the construction could be finished safely and reliably．

Research conclusions: The theoretical calculation and analysis with the finite element method were carried out for the bridge and the objective control values of every construction stage were determined to obtain the adjustable ranges of the cable force of the buckle cables，the jacking and lowering amount at the support points，the scale of post anchor force and the amount of the counterweight for the side span steel girder to achieve the " pre － control" ． According to the in －situ monitoring values of the geometry，internal force and cable force during the construction，the active control strategies and measures of pre － raising the steel truss members，tensioning the buckle cable and the post anchor cable，temporarily loading the side span steel girder and jacking，lowering and vertical moving the support point were taken to timely adjust the internal force and geometry of the structure for realizing the " process control" to achieve the successful closure of the bridge．

Research conclusions: From the comparison of the model＇s conventional onstrained inversion result with the electrical parameter result，it could be seen that the imaging effect of the constrained inversion with prior information was better than the conventional inversion． The method was used for the data processing，and the comparison of the results before and after constrained inversion for the Fangdoushan Tunnel showed that the constrained inversion results of the geological structure such as the fold，fault and karst more tallied with the real situation．

Research conclusions: From the comparison of the seven parameters of the maximum drawing and compressive stresses，the vault settlement，the ground settlement，the axial force of the anchor arm and the maximum drawing and compressive force of the lining，it can be seen the single － wall pilot method is the optimal excavation method，followed by six － hole CRD method，based on taking the 0． 3 m thick spraying concrete lining and 5 m long anchor arm as the support paramters． The research result is reasonable and has the reference to the design and construction．

Research conclusions: From the analysis of loading bearing of the different lining rigidities of the shield tunnel，it is concluded that only increasing the rigidity of the segment alone can not improve the seismic performance of shield tunnel，but increases the load on the segment． With the increase of the rigidity of the tunnel lining，the displacement of the lining structure is reduced by less than 2 mm，thus it is not obvious to restrain the deformation of the shield tunnel by increasing the lining rigidity under the effect of earthquake．

Research conclusions: Based on the construction practice of cement emulsified asphalt mortar cushion for a CRTSII slab ballastess track of one high － speed railway， the analysis is made for the causes for the common problems after pouring in the course of construction of，namely，the micro cracks happen in the joint area between the slab and the mortar or the mortar is not full and slices in some areas，and a large number of the tiny bubbles，the larger bubbles，the bubbles of connecting each other from top to down happen and the asphalt bead separate out． The relative measures are presented from the fields of the edge banding technique for the track slab，the pouring technique，the mixing technique and thecontrol of raw materials to improve the construction quality and it can be as the reference to the similar works．

Research conclusions: ( 1) The selection of the curing agent and the other auxiliary agents used in the epoxy resin mortar is crucial to cutting the toxicity of the epoxy resin mortar，especially the curing agent has more impact on the toxicity of the mortar． ( 2) Adding the appropriate amount of cements and sands can obviously reduce the contraction of the resin to avoid the crack of the cohering surface． ( 3) The cohering strength of new － type low toxic epoxy resin mortar can reach at the 20 MPa for one day，the cohering strength after 3 days can meet the design requirement of planting reinforcement bar and its final strength can reach at 60 MPa with the contraction rate of about 0． 3%． ( 4) When the planting depth of the smooth round reinforcement bar is not lees than 15 times of the reinforcement bar diameter and the planting depth of the screw thread reinforcement bar is not less than 10 times of the reinforcement bar diameter，the drawing force can yield the reinforcement bar，so it has perfect applicable value in the planting reinforcement bar engineering．

Research conclusions: From the the analysis it is concluded ( 1) The external lightning protection should be used along with the internal lightning protection for the lighting protection for station building． ( 2) The equivalent potential bonding is the most critical measure for lightning protection． ( 3) The comprehensive earthing requirements of 1 ohm has not to be meet by every building．

Research conclusions: From the analysis it is concluded ( 1) Before construction the simulation analysis of the whole tensioning process should be made to make sure the cable tensioning is in control． ( 2) The real － time and tracing monitoring should be conducted during construction． ( 3) The calculation result should be compared with the monitoring result to prove the validity of the simulation analysis with finite element and the feasibility of the construction plan．

Research conclusions: As the large underground space is of large space with the complex functional composition，its design should follow the concept of the " safety，comfortableness，greenness and efficiency" to better the planning and functional layout and deal with the relations between the internal and external traffic organizations and the surrounding environment． The designs of the building，structure and mechanical and electrical systems must meet the demands of the characteristics and function of the large complex of underground space to give full play to the advantages of intensive and efficient use of the large and complex underground space for promoting the sustainable development of the large，complex underground space．

Research conclusions: ( 1 ) The excavation face of shield tunnel has its minimum supporting force and maximum supporting force． It means that the supporting force has a reasonable safely range． When the supporting force is out of range，the soil around the tunnel is easy to be damaged，or the over settlement or over rising appears to the ground surface when the tunnel is shallow． ( 2) When the tunnel buried depth is bigger than 1． 5 times of the tunnel diameter，the surface point can not effectively reflect the deformation of soil around the tunnel，and at this time，the soil deformation should be monitored and controlled by the monitoring spots in the tunnel． ( 3) The safely range of supporting force increases with the increase of the tunnel depth． When the tunnel is shallow， the safely range of supporting force is very small，and at this time，the heap loading on the ground should be used to increase the tunnel buried depth equivalently for increasing the supporting safely range and reducing the construction difficulty．

Research conclusions: Taking the form and depth of the foundation and the relation between the bridge pile and the spatial location of metro into account，the adjacent grade of the bridge to metro can be divided into 5 levels． The present bearing capacity of the adjacent bridge can be assessed by checking and diagnosing the current appearance，working state and dynamics characteristics of the bridge structure． Based on both of the adjacent grade and reliability evaluation results，the safety risk of adjacent bridges to metro construction can be classified into the 4 levels: Ⅳ，Ⅲ，ⅡandⅠ．For the different safety risk levels，the corresponding measures should be taken． It has been applied in construction of the Wuhan metro adjacent to bridge，obtaining good result．

Research conclusions: The national railway＇s technology economic factors present the improving trend year by year． The scale but inefficiency was the main reason for the low efficiency of the comprehensive technology; In the long － term，the technical innovation and enhancing the technical and economic efficiencies are the way for the national railway to realize the harmonious and sustainable development．

Research conclusions: The labouring management mode of the " frame － type construction brigade" is a way to build a powerful team in implementation force，with changing the situation of separating the management level with the laboring level． The investigation and analysis results showed the relative policies on the management of " frame － type construction brigade" should further studied in site，the investment for the on － the － job training should be increased，the manage ment of the person taking post with certificate should be strengthened，the backbone management and technical persons should go into the basis labouring team and the " head of contracted labour " mode should be eliminated to improve the working and living conditions of the migrant workers and give full play to the superiority of the management mode of the" frame － type construction brigade．