Research conclusions:Based on studying the overall development plan，the space distribution，industry layout plan and passenger flow distribution of the Guanzhong Urban Agglomeration，the skeleton of network was defined．Finally，the circular radiative network structure of a " V" shape main frame was recommanded with Baoji － Xi'an － Weinan as main axis and Xi'an as the center．

Research conclusions:The Baicheng railway is planed as a one － station form with arrangement in a horizontal line for the passenger and freight traffic ．The Baicheng Station is a passenger station and also a technical operation station to deal with the passenger and freight transport in the region． The Changchun － Baicheng － Wulanhaote rapid railway should be lead into the Baicheng station by the direction orientation，and the Baicheng Station should be arranged in a horizontal line for the passenger and freight traffic． The overall layout of the small railway region is not suitably arranged as the separate lines for passenger and freight traffic，which is adopted to the large and medium － sized railway terminal．The one － station type arrangement or cross － type junction arrangement or in － line arrangement should be adopted to the small railway region． This can set an example for research and design of the overall layout of the railway terminal(region) ，especially of the small railway region．

Research conclusions:From analyzing a number of factors that affect building the Henggang northwest connecting track for passenger traffic one by one，it can be seen the relative passenger stations and the track capacity are good in adaptability，and on consideration of the function of railway station，being convenient for the passenger travel and improvement of the terminal layout，it is necessary to build the Henggang northwest connecting track for passenger traffic．

Research conclusions:The study shows the boundary angle should be used for calculating the safety distance for high －speed railway and the passenger dedicated line of ballastless track，and the rock displacement angle should be used for calculating the safety distance for normal speed railway． Moreover，combined with engineering examples，the method and way for the railway alignment in goaf are presented，including the comparison and selection of the railway alignments in the periphery of mining area，local optimization of alignment in the mining area and the railway alignment based on calculation and monitoring of the deformation of goal ．

Research conclusions:The study results showed that the width of the critical fissure was the key factor for the collapse of covered karst due to the subgrade erosion，the soil property，the compactness and critical hydraulic gradient of the cover，and the collapse width of the critical fissure of the covered karst subgrade was about 2 ～ 4 mm． For the dissoluble rocks subgrade with development of erosion fissure，while the fissure width was less than or equal to 3 mm，or the permeability of karst subgrade was less than or equal to 47Lu，the covered karst subgrade would not collapse under the natural condition．Therefore，it is recommended that the 47Lu should be regarded as the permeability critical standard for grouting quality of karst subgrade．

Research conclusions:The calculated results show that，the hyperbolic tangent modulus method presented in this paper has high accuracy in predicting the settlement of passenger dedicated railway composite foundation，and it can forcast ahead of time before construction．This technique may be potential to calculate settlements of passenger dedicated railway composite foundation．

Research conclusions:(1) When the rainfall is less than 160 mm and the groundwater can not meet the irrigation requirement，the sand protection with the project ( machinery) should adopted．When the rainfall is from 160 to 280mm，the sand protection with the project should be used along with the plant and small irrigation． When the rainfall is bigger than 280mm，it is unnecessary to conduct small irrigation，but needs pouring water on the plant root． ( 2) The plant protection of trees and shrubbery belt should be arranged with intervals，and the tree spacing should be 2 m×3 m and the shrubbery spacing should be 2 m×1 m or 2 m×1．5 m．3 The corresponding specifications of grid and the topography should be adopted along with some sand － protection barriers to the sand protection with the project． The branch or earthwork grid should be 1 m × 1 m and the downsand height should be 2－3 m． In the far sight situation，one or two sand－protection barrier should be used with height of above 3m，but in no far sight situation，the two or three sand－protection barriers should be used．(4) If the included angle between the alignment of a road or railway with the wind direction is less than 30 degree，the protective width should be L* sin β according to the current code ( β is the included angle between the wind direction and the track) ．(5) The film catchment，organic plant and fungi hatching cover can be used for the sand protection．(6) The sand protection should be combined with the tourism and economic development．In the early stage，the investment can increase appropriately．

Research conclusions:To ensure the safety of the heavy － haul railway bearing 40 t axle load of vehicle，the large cross－section rail with high strength． should be used． When the rapid relative displacement of the beam and rail is not more than 4 mm，the span of the bridge for the heavy － haul railway bearing 40 t axle load of vehicle should not exceed 40 m，and at this time，the minimum limit value of the vertical line stiffness of the pier is more than the value in the " Design Specifications for High － speed Railway" ． Therefore，the vertical line stiffness should be controlled by the pier stiffness according to the calculation to make the braking force born by the rail and bridge pier．stiffness should

Research conclusions:The research result shows with the increase of the variation range of the system temperature of the cable － stayed bridge，the expansion － constriction force increases obviously． The modified elastic modulus of cable has less effect on the additional expansion － constriction force and braking force，but has big effect on the additional flexural force． The additional expansion － constriction force calculated by using two different longitudinal resistance models are almost the same，but there is distinct discrepancy in the calculation results of the flexural force and braking force．Application of the fastenings with small resistance can decrease the additional longitudinal force in CWR，so it should be used for the CWR on the side span of the cable － stayed bridge and on the approach bridges on consideration of the engineering cost．

Research conclusions:By the means of building the track － bridge － pier integrated model for the rail，turnout slab，concrete base，girder，pier and abutment，the load bearing characteristic of the longitudinal connected concrete base is obtained． It shows the longitudinal connected concrete base is mainly effected by the temperature force and braking force．Application of stiffness reduction theory and limit state design method for the longitudinal connected concrete base is an effective supplement of the previous study on the concrete basein turnout area on bridge． It can provide the reference to the similar works in the future．

Research conclusions: (1) The structure system of tower pier and beam consolidation was selected．The advantage of this scheme is its bigger stiffness and better overall performance．(2) By adding a connection pier，the overall stiffness of the structure increased by 20% ，and the dimensions of the cables reduced by 16% ． After a comprehensive comparison，an auxiliary pier is added on the large mileage side． ( 3) When structural dimensions of the main beam were optimizaed and selected，the scheme 8 has the best performance and is recommended for this bridge．(4) After a comprehensive comparison，the transverse two － support system plan is selected．(5) The wire pipe saddle is recommended for the bridge because it has more advantages and is more suitable for the requirements of high － speed railway bridge．

Research conclusions: Taking the long － span continuous rigid frame bridge with( 90 + 168 + 90) m high pier in Shanxi province as the engineering background，the basic principle related to the structure stability is discussed and the stability of the high pier，the stability of the longest cantilever during construction and the stability in complete stage of the bridge are analyzed． From the calculation results it can be seen that for the bridge presented in this paper，the temperature effect has a little influence on the high pier stability，the wind load along the bridge axial direction has the most negative impact on the structure stability in the construction stage of the longest cantilever，and during the complete stage of the bridge，the lane load and the load of the crowded people set on the middle span has the most negative impact on the bridge stability． Furthermore，wind has a little influence and the influence of the temperature effect can be ignored in this stage．The calculation results also show this bridge has a good stability during its construction process and in the complete stage of bridge．The calculation and analysis processes presented in this paper can provide the reference to the similar works．

Research conclusions: The analysis results show that the segment＇s mechanical properties along the vertical direction of the tunnel are big different，and the deformation features of each cirque are not the same and big different from that obtained by the conventional mean value continuous model due to the differences of the external load of the segment along the longitudinal direction of the tunnel and the non － continuity of the joint． The grouting pressure and jacking force have apparent effects on the mechanical properties of segment，and the mechanical properties of segment in staggered joint are quite different from the straight joint．Moreover，the staggered joint structure is better than straight joint in the overall stiffness．

Research conclusions: The pile and beam underpinning protection scheme and tracing grouting protection scheme were presented to overcome the problems of the deformation and settlement of the pipeline caused by shield machine under －passing the pipeline． The introduction was given to the advantages and disadvantages of these two schemes． The tracing grouting scheme was chosen． Although，with the tracking grouting scheme，the deformation of the pipeline was not controlled accurately，but the deformation was controlled to the allowable range． In addition，the tracing grouting scheme had the features of using smaller grouting device，occupation of less land，easy operation，low cost and being available for control of the pipeline settlement． Finally，the safety of the pipeline was ensured by adopting this scheme while the tunneling of the shield machine was strictly controlled with the synchronous grouting and informatization construction．The project can provide the reference to the similar works．

Research conclusions: At present，according to the " Technical code for Railway Gas Tunnel" ，the absolute gas emission volume of 0.5 m3/ min is regarded as the boundary standard for grading the high gas and low gas．This standard is too low so that some tunnels that could be built with the standard of the low gas are regarded as the high gas tunnel．In this way，the construction investment goes to waste by taking some unnecessary measures，such as explosion －proof and reinforcing the tunnel lining．On the premise of meeting the ventilation requirement，it is more appropriate to regard the gas concentration of 0.5% in the return air flow as the the standard for grading the high gas and low gas．

Research conclusions: Considering that the lightning strike to the high － speed railway happens frequently and based on the calculation and analysis of the flashover of the OCS caused by lightning，it is proposed that PW ( protection wire) should be arranged on the top of the pole and the positive feeder should be installed with compound insulator in Auto －Transformer ( AT) power supply，and at the same time，the arrester and PW should be grounded to ensure the normal work of the lightning protection devices． It is also proposed that the indexes，such as the lightning withstand level of catenary and the switch － off rate or the failure rate，should be improved．

Research conclusions: (1) According to the light feature of the steel frame roof，by using the flexible tensile cable method，the active loading was conducted to the arc beam of the support base of the steel frame for controlling and adjusting the displacement of steel frame base of the roof and with the monitoring means and feedback design，it could control the internal force of the frame member effectively and avoid the demolishing and reconstruction works for the steel frame structure of the roof．In this way，the construction time of four months and the construction cost of 5.5 million Yuan could be saved．(2) Compared with traditional column support method，the 6． 45 million Yuan could be saved by using this method，with more concept of the green environment protection．(3) When needing to remain the historical style and features of the old building or consider the social influence，but it had no way to demolish the steel frame structure of the roof，the flexible tensile cable method could be used for remoulding and reinforcing the substructure of the frame on the premise of remaining the frame structure of the roof．

Research conclusions:The monitoring data showed that by control of the displacement of the inclined arched pile foundation of the terminal，the good effect achieved to make the deep foundation pit engineering in safe and stable state．It proved the rationality and stability of the design． For the nearby structure，the compressed deformation of the soil could be redeuced by reinforcing the foundation to achieve the obvious effect of controlling the deformation of the structure，and the transmission of the horizontal thrust into the support system for foundation pit could be cut by the insulation pile to get the good control effect of the deformation of the foundation pit．It was necessary to establish the comprehensive and rigorous monitoring system during construction so that the monitored data could be feedback to direct the construction．It not only guaranteed the safety and stability of the foundation pit，but also controlled the influence on the nearby environment and reduced the influence of the construction on the environment around the inclined arched foundation of the terminal．

Research conclusions:The relative parameters for design of the double － row pile was obtained by conducting the construction practice． Compared with the single － row pile，the structure of the double － row pile could effectively control the side － directional deformation of the foundation pit and reduce the bending moment of the pile to make the pile＇s bending moment more reasonable． The research on the computational model on consideration of the interaction between the pile and soil showed the horizontal shift of the soil in the influencing range gradually increased with increase of the excavation depth，but the influence of the excavation of the foundation pit on the horizontal shift of the soil gradually reduced with increase of the excavation depth．

Research conclusions:(1) In the section between Luohu and Grand Theater of Line 1 of Shenzhen metro，it was the first time in China to use the right track and the left track with the arrangement of the up － down overlapping． (2) Compared with the traditional arrangement，such track overlapping arrangement could reduce the space occupation by 25 － 50% and enhance the freedom of the track alignment to solve the problem of the track laying in the crowded space． (3) The lateral space was occupied least by using the track overlapping arrangement and it effectively kept away from the building foundation． (4) If the three － storey side station was used，it was inconvenient for the station management and passenger travel and made the gradient in the track switching section having the " scissors difference" with the big gradient of the right and left tracks and it was unfavorable for the operation． (5) The switching section was inappropriate to be over long because of the complicated line－shape and difficult construction． Otherwise，after service，the tunnel settlement would happen because of the liquefaction of the soil between the tunnels． (6) When designing such track，the attention would be paid to the track ＇s buried depth，parallel and overlapping switching sections，switching section and difference in elevation between the tracks in the overlapping section，and the communication and cooperation would be conducted between the persons of the architecture and tunnel closely to achieve the economic benefits and reduce the construction risk．

Research conclusions: (1) The Line 3 of the urban rail transit in Kunming crosses the Kunming downtown featured with the complicated and unfavorable engineering geological condition and hydrogeological condition，such as the multiple rock － soil layers，rich underground water，sandy soil liquefaction，karst，shallow natural gas，filling soil，soft soil，the special rock and soil and poor regional stability．(2) Based on the comprehensive analysis of the geological condition and surrounding environment of deep foundation pits，the open cut method was used for the foundation pit and the top－down method was used for the section where was limited locally by the transportation condition．(3) The diaphragm wall was available for the interior support and sealing up for the deep foundation pit in the basin with the support of the concrete and steel pipe． The drainage ditch and the collecting well were installed in the foundation pit along with the artificial pumping and draining． The mixing pile and filling were used for the pit base to meet the requirement of anti－float and anti－raising．(4) The the slope excavation could be conducted with the support of the soil nail wall and filling to the pit base for the foundation pit in the essentially level area because of its good engineering geological condition without development of underground water．

Research conclusions: The mechanical ventilation system with open and close operation mode was used for the Dalian subway．The ventilation to the station and sectional tunnel and cooling temperature were achieved by making full use of natural cooling source and the air produced by piston in order to reduce the operation time of the ventilation device as much as possible and save the energy．According to the high air humidity of Dalian in summer，the air pumped into the public area of the station was dehumidified in the hottest months to make the environment more comfortable for passengers．The ventilation system for the station and ventilation system for sectional area equipments were interchangeable． And the operation modes could be switched according to the different conditions to enhance the unilization ratio of the device and reduce the ．first investment and maintenance cost of the device．

Research conclusions: From the design practice of the North Xi＇an Passenger Station of the comprehensive transportation terminal and the analysis of the characteristic of typical national railway terminal，it can be seen for such comprehensive transportation terminal，it is necessary to make overall planing and do the research on project interface and operation management in the stages of the design，construction and operation． Moreover，the station of the urban rail transit should be installed according to the passenger transfer convenience，the scale of stations，the layouts of the station building of the national railway，the square layout and the layout of the metro facilities．

Research conclusions: AHP is suitable for evaluating the target system with hierarchical staggered evaluation index，which objective is difficult to describe in quantity． It is a simple multiple criteria decision － making method which has qualitative and quantitative analysis particularity． In the railway construction project，we have solved the problem by applying the analytic hierarchy process to determining the weights of the bid evaluation，so that the index weight is more scientific and reasonable．