Abstract：Research purposes： Micropiles are defined as small-diameter (typically less than 300 mm). Due to the small resistance of a micropile, micropiles are always designed as a group in earth slope stabilization. Micropiles-slope system is a complex three-dimensional space system and the mechanism of loading is very complex, and there is lack of scientific method to analyze the ultimate resistance of micropiles in slope stabilization. In this paper, the ultimate resistance of micropiles in earth slope stabilization was studied systematically, and influential parameters were also analyzed. Research conclusions： (1) The ultimate resistance of micropiles increases significantly as the pile spacing in row decreases, however, the reinforcing efficiency of a micropile in the group will decrease. This means that, for economical design, the special attention should be paid on the reinforcing efficient of a micropile under the premise of ensuring the ultimate resistance of group piles. (2) The ultimate resistance of micropiles is not sensitive with the pile spacing in line. (3) The total resistance of reinforcement system increases with the increase of anchorage length, and micropiles deformation transforms from rigid-body rotation to substantial flexural distortion due to the increase of anchorage length. For earth slope stabilization, the optimal anchorage length is about 2 times of the length above sliding surface. (4) The research results provide theoretical guidance for the design and safety evaluation of micropiles in earth slope stabilization.

Abstract：Research purposes： Composite lining is often used in the railway, highway and other traffic tunnels, and the primary support is generally designed by layer structure method or engineering analogy method, while the secondary lining is usually designed by load structure method, so it is difficult to evaluate the structural safety uniformly due to the difference of analysis methods. The current tunnel design code only specifies the safety factor requirements of secondary lining, but the composite lining is not a single structure, so it is necessary to study the general safety factor of primary support and secondary lining. And it is necessary to study the load-structure model of primary support to establish the design method of total safety coefficient.  Research conclusions： (1) For composite lining structure with shotcrete and rock bolt support, the surrounding rock pressure increases with the increase of the buried depth, therefore the tunnel support parameters should be adjusted according to the buried depth. (2) The unified design method of composite lining including primary support and secondary lining can be established by the load-structure model. (3) The general safety factor of composite lining tunnel should include the safety contribution of both primary support and secondary lining. When using steel reinforced concrete as secondary lining, the general safety factor should be not less than 3.0, or else not less than 3.6. （4）Different distribution of safety factor on primary support and secondary lining suggested by different design methods is shown in table 2. (5) The result of reanalysis on the structural safety of existing high-speed railway tunnel using this design method shows that when the buried depth is about 300 m, the supporting parameters of tunnel in surrounding rock of Ⅲand Ⅳ grade can be further optimized. (6) The research results can provide ideas and methods for structural design of composite lining tunnel.

Research purposes ： The main line bridge through Luoya Village in the third tenders of Kunming Nan highway connecting is located in deep soft soil area of the Dianchi rift basin. Through analysis of the disease case of main line bridge through Luoya Village，this paper proposes measures and suggestions to control engineering disease of the deep soft soil foundation bridge，to provide a reference for the design and constmction of deep soft foundation bridge in the future. Research conclusions ：(⑴ The influence of negative frictional resistance in deep soft soils on bridge construction and operation safety is more sensitive than general soft foundation， so this must be fully considered in the design，and the adverse effects of unbalanced load or load shedding must be fully thought about in the process of construction，operation and subsequent land development. (2) The design of deep soft foundation bridge must fully consider the necessary basic settings such as constriction road，and the engineering activities that may have adverse effects on the environment of the surrounding area will be strictly limited in design notes. (3) The research result is suitable for bridge engineering design， constriction，security protection and surrounding land development in the deep soft soil area，also provides a reference for the safety constriction of other engineering in deep soft foundation space.

Abstract：Research purposes： Sandy cobble stratum has significant weak cementation, high sensitivity, and poor self-stability ability after disturbance, and there are few related engineering cases and researches on small clear distance shield tunnel underpassing through multiple arch bridge repeatedly in similar sandy cobble stratum. Based on shield tunnel of Chengdu metro line 5 and line 6 underpassing through multiple arch bridge, three dimensional finite element method is applied to analyze the influence of shield tunnel approaching excavation on displacement and internal force of multiple arch bridge in sandy cobble stratum, and the results are compared with that under condition of ground reinforcement, which provides theoretical guidance for the construction of shield tunneling.  Research conclusions：（1）When shield tunnel closely passes through multiple arch bridge which is not reinforced, the unreinforced bridge has large vertical and lateral displacements, the maximum displacement value is 3.92 mm and 0.52 mm respectively. The inhomogeneous settlement of pier and shield tunnel construction cause the axial force, shear force and bending moment of the arch bridge to change, and the maximum internal force occurs at arch foot.（2）For arch bridge foundation and surrounding strata of tunnel, grouting reinforcement can significantly reduce the overall displacement of the multiple arch bridge, the maximum vertical and lateral displacement of the bridge is 2.96 mm and 0.39 mm respectively, with a decrease of 24.5% and 25.0%, respectively. The axial force and shear force changes slightly, the bending moment value decreased significantly, decreasing by 13.1%. （3） The grouting reinforcement method can ensure the operation safety of multiple arch bridge during the shield tunnel construction, and the research results can provide theoretical guidance for the construction of sand cobble stratum shield tunneling.

Research purposes:Shanghai Jinshan Railway link to Pudong Fengxian and Jinshan Railway, can quickly connect Fengxian District of Shanghai with the city center through Shanghai一Hangzhou Railway. In order to meet the travel needs of residents along the rapid growth，and promote the development of Southbridge Town，combined with the controlling factors of Shanghai city rail transit planning，the overall planning of Fengxian District City，Southbridge Town overall planning city planning，this paper explored selection and line scheme of Fengxian suburban railway line station.

Research purposes:The newly-built Lanzhou-Chongqing Railway is the key project of China's”Mid- Term and Long-term Railway Network Development Program"，the Liangshui tunnel of Lanzhou-Chongqing Railway in the construction process encountered in high geo stress，the maximum level principal stress value of surrounding rock is 6. 5-11.3 MPa，tunnel surrounding rock has the characteristics of large deformation and fast speed. In the pre construction tunnel excavation，these conditions occur frequently such as large deformation of tunnel primary support structure，part of the steel arch distortion and fracture，support structure instability，the initial supporting structure to penetrate the lining clearance，removing and replacing arch. After the tunnel links，lining concrete cracking，spelling， the cross section deformation and clearance-intrusion phenomena appear in local section of tunnel lining，which brings great security risks to tunnel construction and operation. Aiming at the problems of tunnel lining，after full analysis of the causes of deformation and cracking，this paper studies the process parameters of the test section for lining demolition for arch，analyzes stress and deformation rules of tunnel support and lining structure by strict monitoring，and puts forward reasonable engineering treatment measures.

Research purposes ： Cavity behind tunnel lining has great effects on tunnel anti - seismic. Based on the background of the Kuokesa tunnel of Dunhuang to Geermu in high intensity seismic region, this paper studies the effect mechanism on seismic dynamic response of tunnel structure with factors such as the location of cavity behind tunnel lining, cavity size, surrounding rock grade and depth, and proposes the rational reinforcement plans to ensure the operational safety of tunnel under the earthquake action.
Research conclusions: (1) Cavity reduces the defomation perfomance and seismic property of lining structure.
(2) The most sensitive factor is surrounding rock grade, following are cavitys hoop size, location, radial size and axial size, and tunnel depth is the least intensive factor. ( 3 ) The grouting reinforcement scheme can reduce tensile stress, and improve the intenal and stress distribution on tunnel lining. The effect of backfilling grouting + reinforcement with arch surround is better than that of backfilling grouting + bolt, the scheme of backfilling grouting + reinforcement with arch surround + bolt has the best anti - seismic effect. (4) The research results have some guiding significance on effect mechanism and optimized reinforcement project selection of cavity behind tunnel lining under the earthquake action.

Abstract：Research purposes： For the high-speed railway lines with more embankment-bridge transition section, the control of the deformation difference between the road and bridge transition section is an important factor to ensure the smooth operation of the train, especially in deep seasonal frozen regions. In this paper, a transitional section of Harbin-Qiqihar Railway is used as a pilot monitoring section, based on the field test data of ground temperature change, frost deformation and settlement deformation, the ground temperature change, frost deformation of subgrade surface and settlement  of subgrade basement of embankment-bridge transition section of high speed railway in cold regions are analyzed, the ground temperature and deformation characteristics are revealed, thus the stability of embankment-bridge transition section can be evaluated.  Research conclusions： (1) At the initial stage of construction, graded crushed stone is easier to be endothermic and exothermic compared to coarse grained soil as for backfill materials of bridge back; the temperature difference in corresponding depth of these two kinds of fillers decreases gradually and tends to 0℃, and finally the new thermodynamic equilibrium is formed. (2) During the freezing process, the maximum deformation of embankment-bridge transition section is 4.6 mm, meeting the requirements of specification. (3) Graded crushed stone being adopted as backfill materials of bridge back, the change process of frost heave deformation of subgrade surface layer with the temporal and spatial can be divided into four stages: the rapid development period of frost heave, frost heave relatively stable period, frost uplifting stage and thaw felling period. (4) The relationship between frozen depth and frost heave deformation of surface layer of embankment-bridge transition section is nonlinear when graded crushed stone is applied. But, the maximum frozen depth of embankment influences the maximum cumulative frost heaving value of the subgrade surface. (5) The settlement of the southern slope is greater than the northern slope. The closer to the northern slope-toe, the settlement and deformation amplitude of substrate becomes smaller. During the period between completion of subgrade construction and track laying, the settlement of basement increases slowly. Currently, the settlement deformation amount of each measuring points of the basement meets the standard requirements. (6) The research results can further provide reference for engineering design, construction and maintenance in the future.

Research purposes: Decay rate(DR)is closely related to the dynamic damping properties of the track， which is used to describe the rail vibration propagation behavior with distance alone the track. Experimental study was conducted to compare DR between Egg system track structure and the standard track form with DTVI2 fastening system. Furthermore，the reasons and control measures of the rail corrugation occurred on Beijing metro were also analyzed.

Research purposes ： The rock - soil mixture slope is a common type of a slope in the Midwest China mountain area. A large number of engineering practices show that some rock - soil mixture slopes after the excavation frequently appear to secondary disasters in especial their bottom on the rock - soil interface and the upper covered a certain thickness of clayey soil，such as landslide and collapse. In addition，the actual combined sliding surface is made up of arc and straight line，however，current stability analysis mode of the rock - soil mixture slope which cant be able to better meet the requirements of this type slope is based on the simplex assumption of circular arc or fold line shape. For this purpose，the paper puts forward a method which is based on circular and linear sliding surface for stability analysis about rock - soil mixture slopes.

Abstract：Research purposes： According to the inter-city rail network construction planning of Zhejiang Province, to carry out the national strategy, strengthen the influence of Ningbo Central Business District(CBD), and meet the needs of the sustainable development, a rail transit need be built to connect Cixi district and Ningbo CBD. Thus, this paper researches on necessity and feasibility of building the rail transit to connect Cixi district and Ningbo CBD, and key problems that the rail transit planning has to solve, such as traffic volume forecast and line route, from the perspective of regional development.  Research conclusions：（1）The inter-city rail transit between Ningbo CBD to Cixi district does not only help the communication between Ningbo CBD and cities around it, but also develops the internal bus system in Cixi district.（2）After traffic volume forecast, we get the line section passenger flow volume is 7.2 thousand people and 14.5 thousand people in the near and far future, and the all-day passenger flow volume is 335 thousand people in the far future.（3）Based on the study of line route, technical standards, system working mode, operation and management and so on, suggestions are given that starting the special research of traffic volume forecast as soon as possible to support the planning and construction of the inter-city rail transit from Ningbo CBD to Cixi district.

Abstract ： Research purposes ： In the previous study of rail transit project, especially during the rail transit network plan，passenger flowis the key basis for determining the network structure and corridors alignment. However, for the traditional forecast method， the workload is huge， the model setup and calculation are complicated， and the time required is long，so it is difficult to push the project forward. This paper discussed how to estimate the total passenger flow and section passenger flow quickly based on the traffic survey， which can take the result in short time as an important reference for the rail transit project. Research conclusions: (1) Rail transit passenger flow forecast can be based on the residents'travel OD survey. (2) According to the trip chain analysis and the functional zone, the total passenger flow and maximum section passenger flow are estimated. (3) Comparing the calculation passenger flow by the method and the exact passenger flow of Tianjin Metro Line 1, there is a very small difference, so the method discussed in this paper is credible. (4) It can be used for the rail transit passenger volume forecast and network scale estimated during the network plan，and it helps to enhance the digitization and credibility of the plan work.

Abstract：Research purposes： With the implementation of medium and long-term railway network planning and the rapid development of China's high-speed railway, the noise problem is increasingly arousing great public concern. The exceeding of ambient noise functional zone on both sides of the railway has become a common problem, and parts of railway projects have not yet passed the environmental acceptance check due to the noise problem. In order to normalize and unify noise control target and noise control measure choice in environmental impact assessment and design, in order to solve the problem of noise control in the environmental acceptance check projects, it is necessary to carry out the research on the principle and measures of railway noise management and the application of the conditions.  Research conclusions： (1)Railway noise control should give priority to take engineering measures on the noise source and acoustic pathways and implement the active control of noise, at least to ensure a reasonable indoor acoustic environment quality. (2)Train noise sources are mainly concentrated in wheel and rail area under the body more than 2.0 meters, barrier above the rail height 2.05 m can effectively shield direct sound from the wheel and rail area and the lower part of the body area. (3)In the sound barrier design, the sound barrier protection range, height, length should be based on the characteristics of the railway source, combined with sensitive point noise reduction requirements, terrain, geomorphology and other working conditions, to adopt different design parameters. (4)The research results can provide reference for the prevention and control of railway noise. 

Abstract：Research purposes： In order to evaluate the driving stability and comfort performance of straddle-type monorail transit, the dynamic interaction between vehicle and track beam is studied. A spatial coupling vibration model of monorail system is established before the calculation program is self-compiled for simulation analysis. The dynamic characteristics of standard PC track beam are calculated and assessed, and the influence of different speed and passenger volume on dynamic responses is discussed.  Research conclusions： (1) The relationship between midspan displacements of track beam and vehicle speed is not obvious in vertical and transversal directions. The transversal and vertical accelerations of track beam and lateral responses of pier top increase with the rise of the travel speed. Augment of passenger volume will increase the vertical deflection of track beam. (2) The transversal and vertical accelerations of vehicle increase with the rise of the speed, and decrease with the enlargement of the passenger volume. (3) Standard track beam performs well, and the monorail vehicle can pass through the track beam smoothly under designed condition of speed and passenger volume. (4) This research result can provide reference for structure design and traffic management of straddle-type monorail transportation.

Abstract：Research purposes： Giving reasonable value of pile negative friction and the depth of the neutral point is a difficult problem which researchers and designers concern most when designing pile foundations in collapsible loess areas. On the basis of analysis of the influence factor of the pile negative friction and the neutral point depth in collapsible loess areas, this paper collects more than 30 research findings of domestic field immersion test to make summary and statistical analysis of the pile negative friction and the neutral point depth in collapsible loess areas.  Research conclusions： (1) By making statistical analysis of massive measured data, it makes clear the upper and lower limit of pile negative friction and the neutral point depth. (2) When pile top elevations are lower than -5 m, the collapsible soil depth of the soil surrounding the pile is less than 6 m and the collapsible class is lower than Ⅱ, the soil surrounding the pile does not apply negative friction to piles. (3) In practical engineering, there is always large load applied on the pile top and collapsible probability and level is far less adequate than field injection, which all make the depth of the neutral point move up in practice and this paper suggests that taking value of the neutral point depth in 0.5～0.7. (4) By making statistical analysis of massive measured data, it suggests that taking negative friction value in 15～35 kPa is factual when design piles in deep collapsible loess areas and there should be more in-situ tests of pile foundation negative friction characters in loess areas. By combing research achievements, this paper can provide the basis for the pile foundation design in the deep collapsible loess area. 

Research purposes: In order to meet the requirement of the construction of Harbin-Dalian High Speed Railway，further improve the efficiency of the railway transportation and shorten the running time，60 kg/m-62# high- speed turnout with speed 350 km/hour is designed out which makes the side allowable speed of turnout achieve 220 km/h. This paper mainly illustrates the critical manufacturing technology and frog assembling and turnout laying technology，to improve the technology of our big size turnout.

Research purposes ： Normally，with the length of steel truss over 80 m，bridge deck system should set stringer break - joint, to reduce joint force the bridge deck system bears in main structure. 108 m steel truss decking of Tongjiang Heilongjiang Railway Bridge adopts light - weight deck structure with pretensioned prestressing concrete track bed by bolting horizontal and longitudinal beams. In order to adapt to the layout of track bed，improve the smoothness of the track and reduce maintenance workload of bridge structure， comparative analysis is conducted through the establishment of finite element model，to investigate feasibility of setting continuous vertical beams in the steel truss deck system of the bridge.

Abstract：Research purposes： As a new method of metro station construction, the pile-beam-arch(PBA) tunneling method is developing rapidly. Neglecting the interaction between underground structure and soil, existing research results mainly focus on surface settlement and pipeline deformation. In particular, there is a lack of research on soil deformation caused by the construction of holes and piles in the four-hole and three-span structure. Based on the Suzhou Street Station of Beijing Metro line 16, the law of surface subsidence in the phase of pilot tunnel excavation was studied through the date of field monitoring. Metro station construction was dynamically simulated with FEM to study soil deformation during the construction in the four-hole and three-span structure.  Research conclusions： (1) "Effect of group cavities" will appear when a plurality of adjacent pilot tunnels are excavated together. (2) Pilot tunnel excavation, construction of first and second lining have the greatest impact on surface subsidence. The proportions of settlement are 32%, 55% and 7%. (3) Supporting system formed after finishing secondary lining construction. In addition to the bottom soil that has vertical upheaval due to unloading after excavation, the other soil mainly was mainly horizontal deformation. After station construction, certain horizontal displacement that moves to the center of station raised in the soil over the vault. Horizontal displacement, caused by stretching deformation of the supporting structure, toward the outside station obvious took place in the soil on both sides of the vault and the soil around the pile end moved to metro station. (4) The conclusion can provide a theoretical basis for the popularization and application of the pile-beam-arch(PBA) tunneling method and provide a reference for similar  projects in the construction and design. 

Abstract：Research purposes： The rails at the transition between bridge and tunnel will crawl longitudinally under the effect of temperature gradient, which influences the stability of CWR. Taking the rail at the temperature transition zone as the research object, the differential equation of rail displacement was established, the mapping relationship between rail temperature distribution and longitudinal displacement was deduced, and the law of influencing rail crawl of ballastless track was revealed in this paper.  Research conclusions： (1) The longitudinal deformation and its range of nonlinear resistance model is much larger than the linear resistance model; for the rail maximum displacement, the non-linear distribution of rail temperature is 5.3%~38.6% higher than that of the linear distribution. It is suggested to consider the non-linearity of rail temperature and longitudinal resistance to accurately obtain the rail displacement at the transition. (2) When the rail temperature difference is constant, with the maximum temperature force gradient ratio k varying from 1.5 to 3.5, the largest rail longitudinal displacement increases only 7% when the transition zone length is 10 m but it increases 26.7% and 32.8% respectively when the length is 40 m and 50 m. Thus, more attention should be paid to the nonlinear rail temperature distribution for the transition with high rail temperature difference and long rail temperature transition zone. (3) The increase of limit resistance of fasteners will reduce the rail crawl significantly, but the influence degree is limited. The rail displacement decreases 40.8%~49.2% with the limit resistance varying from 6.5 kN/(m·rail) to 12 kN/(m·rail), but when the resistance changes from 24 kN/(m·rail) to 30 kN/(m ·rail), the slippage only is only 12.8%~24.4%. (4) The analytical expressions can accurately describe the mapping relationship between the parameters and the rail longitudinal displacement and provide useful references for further study of force characteristics of rail at the transition and improving the stability of CWR. 

Abstract：Research purposes： With the quickening of "Going Global" steps of Chinese railways, the triune "technical standards barrier" problem of the technical regulations, technical standards and technical certification is increasingly prominent. Combined with the problems existing in the railway construction application of the technical standards at home and abroad, this paper compares and analyzes the Chinese and foreign railway engineering construction standards from the standard characteristic, composition, and so on, to better guide China's railway technical standard application in overseas projects.  Research conclusions： (1)In civil engineering, the Chinese standard is generally not lower than the European standard, but in the concrete construction, the better one should be chosen and used after comparison according to the local particular case and other equipment in use. (2)The design problem of the limit state method and the RAMS problem are very complicated and are still in the process of coordination. (3)The research results can provide reference for the application of Chinese technical standards in construction of overseas projects.

Research purposes ： Zhengzhou Metro Line 1 crosses the center of Zhengzhou，which interchanges with many future planning metro lines，and connects with Zhengzhou high railway station，Zhengzhou normal railway station，bus terminal stations and bus stations. How to plan station connection is very important，excellent planning can enhance its capacity of Metro Line 1， can improve the traffic condition of the city， and can help to establish a scientific traffic system. This paper introduces the overall analysis and planning strategy for station connection planning of Zhengzhou Metro Line 1， studies on the implementation steps， positioning analysis， corresponding counter measure and how to determine the type of station.

Research purposes ： The orthogonal cross beam is benefit to the load transferring and construction assembling for the skew continuous steel - box girder bridge. In order to optimize this diaphragm arrangement further by simplifying the structure of the support point，a novel diaphragm arrangement idea was presented in this paper through canceling the inclined diaphragm at the support points of the middle pier. Then the feasibility of this idea was studied and verified.
Research conclusions ： (1) Taking a (30 + 35 ) m skew continuous steel - box girder as the engineering background，the finite shell element models of whole bridge were established. The calculated results show that this novel diaphragm arrangement can meet the design requirement both in the two aspects of the structure global mechanical behavior and local stress. (2) Compared with the oblique crossing diaphragm arrangement，the structure mechanical behavior has little difference regardless of the diaphragm arrangement is adopted when the skew angle is less. (3) By optimizing the structure details of the novel diaphragm arrangement further， its adaptability in the skew continuous steel - box girder bridge with large hollow box section and large skew angle was discussed. (4) The conclusions could provide some theoretical reference for the diaphragm design of the skew continuous steel - box girder bridge.

Abstract：Research purposes： In recent years, urban rail transit has shown a vigorous development trend, construction and operating mileage continued to increase. Valuable experience of urban rail transit project cost control was accumulated from numerous project construction, but there has been many construction cost beyond the cost estimation. Therefore, for the characteristics of urban rail transit, such as large project scale, long construction period, difficulty on construction cost control, it is very significant to study and establish a set of urban rail transit construction cost control measures for the healthy and sustainable development of urban rail transit.  Research conclusions： Regarding to the current problems in the cost management of urban rail transit, the whole process cost control's principle and measures are proposed. (1) In the pre-planning and project approval stage, an appropriate construction scale and construction standards should be chosen by combing with the actual and planning situation of the city, to provide the basis for cost control. (2) In the engineering design stage, the owner should select a preferred design company, and introduce design and cost consulting system. At the same time, design company should strengthen the awareness of cost control and carry out cost-limit design. (3) In the construction bidding and construction stage, the owner should select a preferred construction contractor, and strengthen contract management and on-site management. (4) In the completion acceptance stage, the project managers should directly participate in the completion acceptance and the project final accounts, as well as do the project audit. (5) The research conclusions of this paper are valuable to the construction cost control of urban rail transit. 

Research purposes ： The large section loess tunnel excavation method can use double side heading method， CRD method and steps method， etc. Taking loess tunnel project of Zhengzhou to Xilan high - speed railway as an example，based on theoretical analysis of three kinds of common construction methods，and combined with the primary support sinking of convergence，the surface subsidence monitoring， this paper compared and analyzed the advantages and disadvantages of various methods，proposed the safe and rapid excavation method suitable for large section loess tunnel of high - speed railway.

Abstract：Research purposes： The design of a railway tunnel project in a foreign country have faced several engineering problems such as standardizing the pressure calculation and the design basis of tunnel reinforcement measures for the surrounding rock pressure within volcanic ash layer and the swelling soil stratum, standardizing the seismic design basis of tunnel within high intensive seismic area, optimizing the selection method of service gallery under short construction period. The main purpose of the study is how to adopt China design standards as design basis and adjust details with local conditions to formulate appropriate technical standards and engineering countermeasures.  Research conclusions： (1) Plastic design theory was adopted to determine the surrounding rock pressure around tunnel within volcanic ash layer. Forecast on swelling force shall refer to the ratio of displacement and stress relief during tunnel excavation. (2) Comprehensive measures were used to pre-reinforce the tunnel within weak stratum formed by volcanic ash, by applying chemical churning piles, dewatering and discharging measures in both inside and outside tunnel. (3)Response displacement method and Level I, II performance-based design method was applied on seismic performance verification of tunnel structure. The region that requires seismic precaution was determined based on overburden depth and local geological structure, with corresponding precaution measures applied such as ground grouting, structure reinforcement and joints optimizing. (4) Scheme comparison was used to optimize the form of service gallery, by considering technology, economy issues and applicability. (5) The research results can provide guidance for other overseas tunnel design projects or within soft soil stratum and high intensive seismic area. 

Research purposes ： In the dangerous difficult mountainous area，affected by the railway station setting and the contact line fork， there will be multi - line station tunnel and variable section tunnels， even form a super large section tunnel. When the shallow tunnel is located in stratum of completely weathered granite with abundant water， tunnel construction has the following security risks ： the topographic and geological conditions are poor， developed groundwater， easy to collapse; Primary support force are large， deformation control is difficult， exit the risk of deformation intrude structure ambit，lose stability and collapse; Tunnel should be taken repeatedly excavation support， difficult force transfer， high security risk of support remove and replace. In view of the domestic and foreign less examples and research on super large cross section shallow tunnel in stratum of completely weathered granite with abundant water，there are less research on it. Based on the practical engineering，the problem is studied in this paper.

Research purposes ： Artemisia ordosica is the suitable species for ecological restoration. Studying of dominant families and genera as well as growth characteristics plays an important role in loess slope stability and ecological restoration. Based on the investigation of local natural growth dominant plant artemisia ordosica on loess slope in Yan an area，though the statistics of vegetation density，growth characteristics，and Simpson index of artemisia ordosica of loess slope，the loess slope protection of artemisia ordosica is presented，which provides a reliable basis for the design of compound ecological protection to loess slope in Yan an area.
Research conclusions:(1) The vegetation species diversity is below the medium level in Yan an area，which accords
with the slope vegetation composition characteristics of loess plateau semiarid areas. (2) Artemisia ordosica is the main varieties of loess slope vegetation due to its drought and freezing tolerant. (3) The artemisia ordosica quantity decreases with the increase of gradient or the decrease of soil moisture，but the relative dominance of artemisia ordosica on loess slope increases. (4) Based on the analysis of slope protection of artemisia ordosica，the selection of vegetation type and structural design of eco - engineering for loess slope protection under different slope gradients are suggested. (5) Theresearch results can be the guidance for loess slope ecological protection technology in northwest China.

Research purposes ： Chengdu to Kangding of Sichuan - Tibet Railway is located in the western section of Chinese famous Y shaped tectonic wedge position. Regional structure is complex， and the neotectonics is active. There are three Holocene active faults in this area， such as Longmenshan fault，Xianshuihe fault and Yunongxi fault， which have significant impact to railway route selection. By research on the characteristic of the three active faults in the region works with sticky slip dislocation，creep slip deformation，thermal damage，and the secondary geological disasters caused by strong earthquakes，this paper discussed on the principle of geological selection in complex areas of this kind of geological conditions，to reduce the damage to railway projects.

Research purposes ： Wuhan - Xiangyang - Shiyan intercity railway as the most convenient channel for fast passenger transport with “ Xiangyang - Suizhou - Shiyan city group” and “ Wuhan City Circle” which is an important part of Wuhan to Xi "an railway and an important tourist line in Hubei province. Zaoyang city is located between Xiangyang City and Suizhou City，Wuhan - Xiangyang - Shiyan intercity railway’s target value of speed is 350 km/h. How to realize the value in Zaoyang City and meet local planning requirements，combined with the existing Handan line and Zaoyang station，the Wuhan - Xiangyang - Shiyan intercity railway line and station in the city were researched and compared.

Research purposes:With the development of the electrified railways，lightning is one of the important factors which endangering safe and reliable operation of the traction substation. The lightning accident of the traction substation was occurred from time to time. In order to improve the traction substation’s lightning protection level，it is studied according to the lightning accident of a 220 kV traction substation. It’s a typical accident and the equipments of the traction substation are damaged seriously. This study aims to analyze the cause and the process of this accident based on the calculation of the lightning current amplitude，lightning overvoltage，arcing rate，and the short circuit current，give the strengthening measures of lightning protection to avoid the similar accident.