Research conclusions:As the SRTM DEM and ASTER GDEM data have its own system error，the measures，such as the digital elevation accuracy evaluation，DEM fusion，elevation datum offset and DEM re － sampling，should be taken for improving the DEM accuracy and building a large range，high accuracy and visual digital topographic feature model to assist the analysis of the structural topographic feature，the geological condition of karst hydrology and the development regulation of geological disaster in order to enhance the quality and efficiency of railway alignment．

Research conclusions:In this paper，a new measurement datum is presented． That is to take the WGS84 as the datum ellipsoid to firstly changes the semi － major axis and eccentricity of the datum ellipsoid and then the three translation parameters of ellipsoid centre and three rotation angles of axis can be obtained by using the deflections of the vertical component to build an optimal fitting surface of local ellipsoid with the average elevations of the construction area; At last，the independent precise measurement datum is established with the appropriate map projection method．This method is not only available for the precise measurement for the high － speed railway，but also it can provide the theory basis for the CPIII 3D adjustment．

Research conclusions:The mesozoic magmas are mainly originated from the low crust and middle crust with small amount of the mantle materials into the intermediate magmas． The many evidences showed the magmatic activity in the Indosinian and early Yanshanian epochs were developed under the geodynamic setting of synorogenic thickening crust and were the activated productions of the crust substance in the basement． The middle and late Yanshanian magamatism were probably formed during the postorogenic collapse and it was closely related to the space － time of the mantle underplating． The mixed effect of the zone batch partial melting of the crust with different depth and the end member magma caused the formation of several kinds of magmas in the same period．

Research conclusions:The practice of Yichang － Wanzhou railway indicated that " The survey mode of long tunnel in complex － karst areas avoidance of geological hazards (risk) " could meet the normal railway survey program requirements，at the same time，try to expand the investigation way，add the phase of exploration，combine the exploration with geological forecast，create more opportunities to get more geological information，so the geological disasters could be analyzed comprehensively，and effectively prediction and advanced geological forecast in construction could be made，then，effective measures could be used to avoid geological risks．

Research conclusions:Combined with the special design principle of the earthquake relics and the principles of the minimum intervention，authenticity，reversibility and recognition of the preservation of cultural relics，and based on the analysis of the main structural style and the damage characteristics of the Wenchuan and Yushu earthquake relics，the intension of the anti － seismic reinforcement of the earthquake relics is presented in this paper． Namely，when the reinforcement is conducted for the relics，the reinforcement for the collapse － resistant capacity should be given the first place to the whole structure while the reinforcement of the member of the damaged structure should be given the second place． Also the corresponding reinforcing method is pointed out in this paper．

Research conclusions:From the analysis it can be seen that the ground temperature in depth between 0 and 1.5meters varies greatly under the influence of the air temperature． The ground temperature of the shoulder hole between 1.5 and 10.0 meters decreases year by year because of the cooling effect of the thermal rod，.and in the first 2 to 3 years after the Qinghai－Tibet Railway being open to traffic，the ground temperature falls obviously．So the thermal rod can make the ground temperature down quickly to protect the permafrost．

Research conclusions:(1) Although the rock salt is easily dissolved with water and its strength is reduced rapidly because it contains a large number of soluble salt，but it has good mechanical properties，so it is still available for the roadbed filling and the foundation supporting course of the railway in the Lop Nur with very less rainfall and saturated brine groundwater． (2) When the rock salt is used as roadbed filling，the attention should be paid to the maximum diameter of the broken rock salt because the porosity of rock salt is generally big． At the same time，the rock should be rolled densely while the measures of waterproof and drainage should be taken． (3) The way to determine whether the rock salt can be used as foundation supporting course is consistent to the common geotechnical method，but attention should be paid to the waterproofing treatment to the base of the rock salt．

Research conclusions:(1) The existence of the old landslide mass and the relative loose earth structure were the premises of the landslide happening of landslide． As the landslide soil was weakened by seepage of the continuous rainfall，the weight of soil body increased． The high slope was formed by the earth excavation without taking the appropriate supporting measures． All these factors caused landslides when the rock and earth mass arised from the slide plane．(2) The monitoring of the deep displacement quantitatively verified that this landslide had been movable in many times with the characteristics of multilayer landslide soil． The shallow slide plane was 6.5 － 20.5 m away from the earth surface; and the deep slide plane was 15.5 － 31 m away from the earth surface． The total displacement of slide plane was 13m and the maximum deformation rate of the slide plane was 0.42 mm per day．(3) The monitoring technology for deep displacement was particularly available for the cases that the investment was limited，the geological formation was complicated and the position of sliding surface was difficult to be judged by drilling． It would play a more and more important role in the security monitoring and evaluation of the treatment effect to assist the survey and design of landslide treatment．

Research conclusions:This study showed that，for the steel pipe micro － pile that using pile － cap － beam combined structure，the landslide － thrust distribution back of the pile is big in the end and small in the middle performance " U" type distribution form; Soil resistance before the pile is big top and small bottom performance inverted triangular distribution． Limit sliding resistance of steel pipe micro － pile composite structures ( four row of steel pipe pile + contact beam) is 596 kN，single steel pipe micro － pile average limit sliding resistance for 149 kN． In practical projects，these engineering measures can be used to improve the anti － sliding ability of steel pipe micro － pile such as modify between pile soil，setting support structure before pile，optimize structure distribution form，and so on．

Research conclusions:The analysis of the concentration factors of the hot spot stress of many kinds of joint was made and the shs － N curve of the hot spot stress for checking the steel bridge fatigue was deduced by using the concentration factors of the hot spot stress． The comparison of the fatigue strength of nominal stress of the many kinds of structure details stipulated in BS5400 with the deduced fatigue strength of hot spot stress showed the deduced fatigue strength of hot spot stress was obviously less than the discreteness obtained with the nominal stress method． So the hot spot stress method is available for bridge construction．

Research conclusions:The geophysical prospecting should be used for the karst survey along with drilling． The attention should be paid to the study on the geological structure and the survey method and the detailed and accurate survey report should be supplied． The characteristics of the load on the pile should be considered carefully in design．The reasonable parameters for the calculation of the pile' s bearing capacity should be chosen，The reliable method should used to evaluate the stability of the roof and the scientific experiments should be done if necessary to verify the accuracy of the calculation and ensure the engineering quality．

Research conclusions:The model was established to analyze the structure of the assembled bridge erecting machine．The analysis results showed that the structure of the bridge erecting machine could meet the construction requirements，and its stiffness was stronger than standard bridge erecting machine by about 1． 5 times． With full use of the existing member bars for the this bridge erecting machine，the investment in manufacturing new kind of member bars was much reduced and the cost was saved by 50% ． The bridge erecting machine runs on the slide board with the features of smooth running，easy operation，safety and reliability．It can provide the reference to similar works．

Research conclusions:The method presented in this paper does not only takes the volume of the gas emission as the standard，but also considers the tunnel condition and the layout pattern of ventilation devices to define the gas grade，so with this method to determine the gas grade，many factors should be considered．

Research conclusions:By studying risk management theory，the construction of the railway tunnel risk and the rail tunnel risk grading standards，the conclusions were as follows: (1) Rail tunnel risk index system can make the identification of the risk of future engineering practice changetoo simple，and the basic work can save a lot of repetitive and be difficult to miss some of the factors．(2) The process of risk assessment and management of the railway tunnel and rail tunnel risk grading standards provided a direction for further research and practical application in the future．

Research conclusions:From the analysis of the construction technique and control measure for the channel for catenary in tunnel，it can be seen the construction precision and error can be controlled by using the secondary positioning technique． It means to confirm the type，gap and size of the precast channel and weld the precast channel into one unit with the fixed mould or the steel plate with scale outside of tunnel fiest． Then fix the precast channel unit on the hole position of the channel corresponding to the mould bogie for the secondary lining with special " T" type bolt，and the "T" type bolt will be removed before removing the mould．

Research conclusions:The results show that the total number of trip － out will be high in the typical layout of traction network．which will be 25． 37878 times per 100 kilometer per year． Among them，there are 25.1508 times per 100 kilometer per year caused by striking on positive feeder，account for 99.1 percent．Finally，the paper promotes a improved optimization schemes of the typical layout of traction network ，Take first scheme as an example，the total number of trip － out have only 13.2579 times per 100 kilometer per year． Compared with the typical layout of traction network，the total number of trip － out decreased by 52.2 percent，so which have the important reference value for lightning protection in the future．

Research conclusions:This paper analyzes the principle of the traction return system of TRNF traction network． From the simulation calculation and analysis of the tested data of the return current to the Chongshan substation of the TRNF traction network with return wire for the Chengdu － Dujiangyan Passenger Dedicated Line，it can be seen using the TRNF traction network with return wire can significantly improve the distribution form of the return current system，reduce the proportion of the return current of the rail － earth and cut the impacts on the traction power supply equipment and communications signals equipments． Thus it can provide the design basis for selection of the equipments for the substation and communications signaling systems．

Research conclusions:To carry out competitive monopoly is an objective orientation． (1) From a macro view，the government should give the transportation enterprises superior policy of credit and tax，financial allowance，and the right to develop the resource in some degree． (2) While from a micro view，the government should separate hubs from lines， and let enterprises construct and manage independently． By of way of “allowing line with point” it can help the sustainable development of the whole lines．

Research conclusions:The engineering information management system is built on the base of the Internet according to the construction features of the Major Bridge Bureau． (1) The system has three － level systematical structure in the overall structure， and with the management pattern based on C /S， the system extendibility can be ensured．(2) Application of the engineering information management system can reduce the engineering management personnel＇s working strength，and the all construction informations of a project can be written into the system by one person and shared by others．(3) The system interface is simple and clear with fresh sensation． (4) This system has many functions，such as building construction standing book and consulting and revising the construction information．(5) Most information are called out and generated from the data bank of the system for user convenience． In this way，the writing of user can be much reduced and therefore，the errors caused by the writing can be reduced，the system burden can be cut and the working efficiency can be much enhanced． I