Research purposes:When the tunnels of high-speed railway through loess tableland，it is influenced by the characteristics of high groundwater level and high water content and high classification of surrounding rock and long distance of shallow buried section，the instability and collapse risk of tunnel face are high in tunneling construction. In the stability analysis of tunnel face of loess tunnel with large section,there are most of them focus on the transverse two-dimensional problem of shallow buried short distance tunnel,however,the longitudinal deformation and the advance stability of the tunnel face are rarely mentioned. Research conclusions:⑴In view of the instability and collapse risk about the large section tunnel face during tunneling construction in loess tableland, a three dimensional modified analysis model based on Terzaghi loose soil pressure theory is established,and the formula for calculating the stability of tunnel face in shallow buried long distance tunneling is deduced.⑵The relationship between the stability of the tunnel face and the moisture content of loess in the construction with three-step reserved core method is studied,and put forward the reference value of stable water content of tunnel face in loess tableland is 20%, and put forward safety precaution measure pertinently.⑶The research results can effectively guide the safe construction of the tunnel face of the shallow buried and slow-slope tunnel in the loess tableland, and it provides theoretical basis for longitudinal deformation analysis and advance stability analysis and safety control of shallow buried long distance tunnel.

Load-displacement curve of anchorage structure under different conditions was acquired in the pullout test. Based on the results of pullout test, the essential meso-mechanical parameters of soil and anchorage body was obtained by comparing stress-strain curves under different confining acquired from laboratory biaxial test and numerical biaxial test. The validity of simulation model is verified by comparing the experiment data obtained from on-site pullout test and the simulation mode. In this mode, the features of the axial force and shear stress distributions along the anchor rod and meso-mechanical feature in soils is fully analyzed．

In order to study the effect of fasteners on the vibration reduction of subway tunnel-ground environment, the field measurement and analysis of tunnel structure and ground vibration response caused by vehicle operation under ordinary fasteners and vibration reduction fasteners are carried out, and a numerical model of vehicle-track-tunnel-ground coupling dynamic analysis is established to analyze the vibration reduction effect of vibration reduction fasteners on tunnel structure-ground. Through on-site measurement and numerical analysis, we can know:(1) Damping fasteners can effectively control the vibration response of ballast bed and tunnel wall. When the damper fastener is used, the peak value on the ballast bed decreases and the frequency band shifts to low frequency. Vibration amplification of damper fasteners on tunnel wall occurs in the range of predominant frequencies.(2) The predominant frequencies of the ground measuring point shock absorber fastener a and shock absorber fastener B are 31.5Hz and 63Hz, respectively. There are differences in the control frequency range of the two fasteners. (3) The peak value of vibration acceleration and the Z-level of ground measurement points show a decreasing trend with the increase of the location of the vibration source, but they increase in the range of 15m-30m, which indicates that the vibration amplification phenomenon occurs in the region, but the amplification range is different, so the appropriate fasteners should be selected according to the specific project. (4) The peak value and Z-level of vibration acceleration at the same measuring point on the ground show a W-shaped trend. Therefore, when ground vibration control is carried out, the position of control points should be fully considered and reasonable control measures should be adopted according to specific conditions.

Abstract: Research purposes： Side in karst region, in the process of pile foundation construction and earth excavation of foundation pit, shallow buried box metro tunnel structure appeared sudden subsidence, especially the deformation joint performed significantly, this paper depends on the displacement monitoring data of the box metro tunnel and the deformation joint on both sides to analyze the causes of sudden subsidence of tunnel structure, and studies the effect of subsidence control measures including the shallow layer recharge water, deep layer recharge water and grouting reinforcement. Research conclusions:(1) The maximum cumulative settlement of shallow buried box tunnel induced by support pile construction is 3.3mm, which should be paid attention to in karst area; the sudden settlement of lateral shallow buried box tunnel structure is mainly caused by the exposure of karst cave and the burst of confined karst water in the construction of foundation pit rock-socketed engineering pile.(2) The shallow recharge water can replenish the stratum in a short time, uplift the tunnel and restrain the steep settlement of the tunnel; long-term implementation of deep recharge and pile foundation mud wall protection construction can maintain the underground water level and control the subsidence of side tunnel, but there are problems that deep recharge water may enter the karst cave through karst cracks or aisles and decrease the replenishment efficiency of recharge water.(3) The maximum horizontal displacement of the tunnel under the effective control of "double row pile + steel strand + symmetrical excavation" is 3.0mm. (4) Vertical and oblique grouting around box tunnel can reinforce and stop water, and the grouting pressure should be controlled in consideration of the sensitivity of deformation joints.(5) The results of this study can be used as a reference for the side excavation of shallow buried box tunnel in similar karst areas.

Abstract: Research purposes: The main channel bridge of Qingshan Yangtze River Bridge is the largest span cable-stayed bridge with full floating system in the world. Its pylon is the highest A-shaped pylon in the world and its main girder is the widest steel box girder on the Yangtze River. Its dynamic characteristics are key to structural stress characteristics, which are unique compared with conventional cable-stayed bridges. By adapting ANSYS, spatial finite element model of main channel bridge of Qingshan Changjiang river bridge was established, and structural dynamic characteristics at completion state and largest single cantilever state in construction stage were analyzed, It lays a foundation for further research on seismic and wind resistance performance of structures. Research conclusions: (1)At completion state, structural vibration period of top three order vibration modes are longitudinal wave, symmetric lateral bending and symmetric vertical bending respectively, with corresponding period is 14.22s, 6.25s and 4.78s respectively. At largest single cantilever state, structural vibration period of top three order vibration modes are lateral bending, vertical bending and vertical bending respectively, with corresponding period is 8.4s, 4.44s and 2.93s respectively. The Structure in two states above are belong to long-period structure. (2)Under both states, lateral stiffness of structure is weak, and it is sensitive to wind-induced vibration response in transverse flow. (3)By adopting A-shaped pylon, ultra-wide main girder and double-cable plane, structural torsion frequency and anti-torsion stiffness are improved, and anti-torsion stability of structure is restrained. (4)At completion state, coupling phenomenon of different vibration mode appears in higher-order vibration modes of structure,and corresponding to largest single cantilever state, coupling phenomenon of different vibration mode appears in lower-order vibration modes of structure.

Research purposes: Aeolian sand is a soil with low cohesion and poor self-stability, which brings great difficulties to tunnel design and construction. Based on the Wangjiawan Tunnel of Menghua Railway, this paper deeply studies the instability characteristics of the tunnel face of deep-buried aeolian sand tunnel under different face angles through physical and mechanical tests, numerical simulation and theoretical analysis. Research conclusions: (1) The instability zone in front of the face of the face has a wedge shape and then expands upward to form a closed bulb-like area. As the angle of the face increases, the lower part of the instability zone expands, the upper part shrinks, and the stability of the face is gradually improved. (2) The angle of the face of the face has little effect on the longitudinal and lateral dimensions of the instability zone. The boundary is about 1 times of the front of the face of the face, and the lateral span is about 2 times of the hole; (3) There is a pressure arch in the unstable soil, and the apex is located between the hole and the bottom of the arch. As the angle of the face increases, the apex of the pressure arch formed by the instability zone moves downward and the span decreases. In addition, this paper deduces the formula for calculating the support force of the face in the deep-buried aeolian sand stratum, and puts forward relevant design and construction suggestions.

Abstract: Research purposes: The excavation of subway tunnel will induce settlement, or even damage, of existing buried pipelines. In order to understand the co-deformation law between pipeline and soil, a three-dimensional finite element model was established to simulate tunnel excavation transversely undercrossing an existing pipeline. Contact elements were used to simulate the pipe-soil interaction. Settlement, internal forces of the pipeline, detached range between pipeline and soil induced by tunneling were calculated. Influences of elastic modulus of soil, bending rigidity of pipeline, diameter of the newly built tunnel, vertical net distance of tunnel and pipeline on displacement and internal forces of the pipeline were analyzed. Variation laws of normalized settlement and normalized bending moment of the pipeline with respect to the relative pipe-soil rigidity factor (K) were studied. It is recognized that the pipeline can be categorized as flexible pipeline, elastic pipeline and rigid pipeline according to the factor K. Simple formulae to compute the maximum bending moment and the maximum settlement of pipelines were given. Centrifugal model test and in-situ measurement were conducted, results from which were compared with that by numerical simulation. Good consistency was attained. Research conclusions: (1)Settlement and bending moment of the pipeline decrease with the increase of the factor K. (2)A pipeline with K<0.1 is a flexible one which deforms as much as what the soil settles with no detachment occurring between them. The settlement of the soil can be taken as that of the pipeline and so the internal forces of the pipeline can be calculated. (3)A pipeline with K>100 is a rigid one which refuses to deform with the soil with detachment easily occurring between them. Resistance of the soil on the pipeline can be found out and used to compute the internal forces of the pipeline. (4)A pipeline with 0.1≤K≤100 is an elastic one which obviously interact with the soil with detachment possibly occurring between them. The proposed numerical model in this paper, which takes into account the detachment between the pipeline and the soil, is suitable to be employed for the computation of the mechanical behavior of the pipeline. (5)The research results provide theoretical guidance for safety evaluation of the existing pipelines during traversing construction.

The railway prestressed embankment (PE) is still a new reinforcement technology at home and abroad, so its deformation characteristics haven’t been systematically studied yet, and the relevant reinforcement design theory is in an exploratory stage. It is necessary to understand the working state and enhancement performance of PE by numerical method. In view of this, with the help of ABAQUS code, the simulation system of PE was established. Meanwhile, by designing three sets train axle loads and taking the traditional embankment as a reference, this paper analyzed the effects of PE on the control indexes of deformation and mechanical states of reinforcement components under different prestress reinforcement parameters, which is expected to provide a good reference for the design of PE.

Abstract：Research purposes: In the actual geological environment, all kinds of deformation and failure of tunnel excavation are the product of comprehensive influence of various factors. However, due to the layered characteristics and structural form of bedding structure, tunnel excavation in such geological environment is determined, and the deformation and failure of surrounding rock after stress have certain particularity. Taking Baoyun Tunnel of a high-speed railway as an example, this paper carries out numerical simulation analysis and evaluation on damage and deformation of tunnel surrounding rock under the action of hard-soft interbedded bedding structure. The deformation, progressive yield and stability of tunnel surrounding rock under the influence of different rock thickness are studied. The deformation and failure modes of hard-soft interbedded composite tunnels are given when the strength is reduced to the limit state. Research conclusions: (1) Thin-layer bending deformation is the main deformation form of hard-soft interbedded parallel tunnel excavation under the action of different rock thickness structures. Thick-layer surrounding rock shows obvious slip, but the deformation value is small. The deformation characteristics controlled by rock thickness should be considered in tunnel support design. (2) The yield zone of the hard-soft interbedded combination mainly distributes along the bedding to the soft rock. The smaller the thickness of the interbedding, the larger the yield range. The yield zone of 0.2m bedding is typical. When the thickness of the interbedding exceeds 0.4m, the yield zone of the arch waist along the bedding decreases rapidly, and with the thickness increasing, the yield zone of the two directions decreases continuously. (3) Under the condition of strength reduction, when the thickness of stratum exceeds 1.5 m, the stability safety factor tends to be fixed. The strength of surrounding rock is mainly controlled by soft rock itself, and the influence of hard-soft composite structure is reduced. (4) When the thickness of strata is small, the deformation mode of tunnel surrounding rock is mainly rock bending. With the increase of the thickness of strata, the deformation mode gradually changes to bedding sliding, and both sliding and bending coexist. The above research results have significant theoretical significance and engineering value to promote the smooth construction of the high-speed railway.

Research purposes: Caofeidian dredger fill contains a large number of fine particles, and has high salt content. Conventional foundation treatment methods can not meet the requirements of strength and deformation. Chemical solidification method has great advantages in treating saline dredger fill in this area. In this paper, 10% mineral powder is used as the main curing agent, sodium silicate, quicklime and gypsum powder are used as additives. Strength tests of saline dredger fill solidified with single, double and three additives are carried out respectively. The changing rules of unconfined compressive strength of saline dredger fill under different mixing materials, ratios and ages are analyzed. The research conclusions are as follows: (1) The unconfined compressive strength of Caofeidian saline dredger fill can be greatly improved by the mineral powder solidifying agent, among which quicklime has the greatest influence on the solidifying effect of the mineral powder solidifying saline dredger fill; (2) 10% mineral powder + 1.0% quicklime, +0.8% sodium silicate + 1.5% gypsum powder is the optimum proportion of the mineral powder solidifying agent. The 7-day unconfined compressive strength of the stabilized soil reaches 2007 kPa, and the 28-day unconfined compressive strength increases to 3370 kPa, which fully meets the requirements of foundation strength. (3) The research results provide guidance and theoretical basis for railway foundation consolidation projects in Caofeidian and other coastal saline dredger fill areas.

Abstract: Research purposes: To solve the problem of large deformation in the excavation of soft slate formation tunnel with high ground stress, the support structure of one primary support + double-second lining is adopted for field test, and the deformation and stress of the primary support, steel arch and two-layer second linings are measured. The main research objective of this paper is to analyze the effect of this support structure on controlling large deformation of soft rock tunnel with high ground stress and the feasibility of this supporting plan. Research conclusions: (1) The traditional initial support method is not effective in controlling large deformation of high ground stress soft rock tunnel. (2) Strike direction and dip angle of strata will have impact on the deformation and stress of soft rock tunnel with high ground stress. Generally, the extrusion pressure which perpendicular to the direction of soft Slate formation (inclination line) is the largest.(3) The double-second lining structure is adopted to make the primary support and surrounding rocks deform together and eliminate part of the surrounding rock pressure. Then the first second lining plays a strong and stable supporting role and most of the surrounding rock pressure is beared, so that little stress is beared by the second lining of second layer and plays a decorative role. Therefore, according to the perspective of long-term rheological property of high ground stress soft rock, the double-second lining structure has a good guarantee effect on long-term stability and safe operation of high ground stress soft rock tunnel.(4) The research results can provide valuable reference for the construction of similar projects.

Abstract: Research purposes: Side pile is one of the main load-bearing members in PBA construction, and the parameters of side pile are of great significance to control the deformation of station. Therefore, based on a subway station constructed by PBA method in Xi'an loess area, this paper studies the influence of different depth and diameter of soil entry on the deformation of surface and side pile, which provides a reference for the selection of side pile parameters of PBA method in loess area in the future. Research conclusions: (1) The surface settlement curve distributes symmetrically along the middle line of the station, and increases gradually from both sides to the middle. The horizontal displacement curve of side pile shows the form of "bulging belly".(2) With the increasing of the depth of soil entry, the settlement of the surface and the lateral displacement of the side pile decrease. With the increasing of diameter, the surface subsidence and the lateral displacement of the side pile decrease gradually. The reduction rate decreases with the increase of related parameters. (3) From the point of view of variation amplitude, when the depth of soil entry meets the requirements of bearing capacity and stability, increasing the depth of soil entry has little effect on improving the displacement of side pile. The horizontal displacement of side pile can be effectively improved by properly increasing the diameter of side pile. (4) The depth of soil entry is of great significance to the distribution range of plastic zone. If the depth of soil entry is too small, a large plastic zone will be produced, which will affect the overall stability of the structure.

Abstract : Research Purposes: In order to select the dominant modes suitable for rail guided wave detection, the governing equation of rail guided wave propagation was established by Semi-analytical Finite Element (SAFE) method and Hamilton principle. The dispersion characteristic curves of rail guided wave in the frequency range of 0-100 kHz were subsequently calculated. Meanwhile, the Finite Element (FE) model was established to analyze the vibration mode of rail in the low frequency range, which has verified the accuracy of the SAFE method. By combining the FE and SAFE method, the ideal rail vibration modes were classified, and the ideal guided wave was excited and verified based on the corresponding deformation. Research Conclusions: (1) With the increase of frequency, the number of vibration modes of waves increases rapidly while the dispersion effect decreases. (2) For the basic vibration modes of rail, the section deformation gradually concentrates on the local area, the torsional vibration mode is suitable for rail web detection, both the transverse and vertical bending vibration mode are applicable to the inspection of rail bottom defects. (3) The ideal guided wave can be successfully excited by applying load at the maximum deformation position of the ideal mode. (4) The results can provide theoretical reference for the design and optimization of the guided wave sensor and the detection experiment.

Abstract: Research purposes: To investigate to the buffeting response effect mechanism of long-span bridges subjected to non-stationary wind speed, take two sets of observed non-stationary samples as examples, an three-layer accurate modeling method for non-stationary wind events were firstly proposed, then a quantitative indicator that can effectively measure the degree of non-stationarity were obtained by the recurrence plot. Furthermore, the fast CQC method (i.e., pseudo excitation method) was adopted to establish the buffeting analysis method of time-varying wind-bridge system subjected to non-stationary winds. Finally, take a mountain suspension bridge as an engineering background, the similarities and differences of buffeting responses of long-span bridges under strong and weak wind speeds were compared. The research results can provide technical support for refined wind-induced dynamic response and wind-resistance design of long-span bridges. Research conclusions: (1) The weak non-stationary winds can be simplified as stationary buffeting theory that can significant improve computational efficiency; (2) The more rapid variation rate of the wind fluctuation indicate that the structural vibration response is further away from its steady-state; (3) Traditional stationary treatment for the strong non-stationary winds (10 min constant mean plus stationary wind fluctuation) may underestimate the bridge buffeting responses, thus refined transient analysis may be required.

Research purpose: In order to study the performance of double Halbach electrodynamic suspension (EDS), which is very helpful for engineering design, this paper proposed an analytic model of such device, based on 3D arrays, verified by finite element method (FEM) and experiment. Research conclusions: (1) Using the second order vector potential (SOVP), we established the differential equations of electromagnetic field, in the spaces, which divided into three parts, due to the different conductivity. Under the reasonable assumption, we can get the general solution of SOVP, by the separation of variables. (2) We used the magnetic charge method to solve that static field. (3) Those undermined constants in the general solution can be confirmed both by edge condition and static field, And In that case, we can get the expressions of magnetic field in different spaces, based on which, using magnetic charge methods, the forces can be solved. (4) We compared the fields and forces results, which were calculated by analytic model and 3D FEM, and it showed that, the average relative error is about 0.7%. The 3D FEM model were built in ANSYS software. (5) In the last, we established a rotation experimental platform, thus to simulating the workings of double Halbach EDS. We tested the forces, using this platform, compared with analytical results, and the average relative error between them is about 10%.

Research objective: Stability of ballasted track structure includes stability of track panel and stability of ballast bed. Taking a meter-gage railway in a mountainous area as an example, this paper studies the stability of ballasted track over the slope of 250‰ and the limit slope. Firstly, the meter-gage railway’s longitudinal resistance test of ballast bed was carried out. Based on this, we established the finite element model of track panel and analyzed the stability of the track panel under different slope and different fastener resistance. Then the three-dimensional finite element model of ballasted track with meter-gage railway was established and the influence of slope and vertical curve radius on the stability of ballast bed was studied. Finally, this paper put forward suggested value of the limit slope and vertical curve radius according to the relationship between the fastener resistance, the ballast bed resistance and the stability of large-slope ballasted track. Research conclusion: (1) Based on the analysis of the data, this paper provides ballast's longitude resistance parameter, and this data is used to analyze the stability of the track panel. Analysis result shows that the stability of the track panel decreases with the increase of slope. When the resistance of the fastener is no more than 10kN/m, the limit slope reaches 500‰. (2) And the stability of ballast bed gradually weakens with the increase of slope. Under the action of train load, the maximum slope of ballast to maintain stability is 500‰. (3) According to the calculation, it is found that the stability of the ballast bed near the convex vertical curve is weaker than that of the straight slope section, and its stability gradually increases with the increase of the vertical curve radius. In order to maintain the stability of the ballast bed, the vertical curve radius cannot be less than 400m when the slope is 250‰. (4) The research results can provide theoretical and experimental basis for the stability analysis of meter-gage railway ballasted track structure on large slope.

Research purposes: With the accelerated construction of the “eight SNs and eight EWs” HSR network and regional intercity fast rails, HSR in areas of low-mountain and shallow-hill, which is different from HSR in mountainous areas and HSR on plain, is progressing orderly. For Chengdu-Chongqing economic area, it is represented by the inter-city railway of southern Sichuan, Chongqing-Yichang Section of Chongqing-Kunming railway, Chengdu-Zigong railway, Chengdu-Nanning-Dazhou railway, Mianyang-Suining-Neijiang railway, Chongqing-Wanzhou railway, etc. This paper takes the inter-city railway of southern Sichuan as an example, summarizes the route selection design for HSR in southwest area of low mountain and shallow hills passing through second-tier cities, so as to provide reference for the route selection and engineering treatment of the same type. Research conclusions: (1) the arrangement of route and stations for new HSR should varies by time and place, be compared and studied combining local urban planning, existing network status and transportation organization needs, either by setting new passenger stations or by leading into existing stations. (2) It is large ground structure which is critical to HSR route selection in low-mountain and shallow hill areas, other than geological conditions. During preliminary design, relevant special assessment and agreement signing should be well done under the organization of the Employer. (3) Profile design in such area is better to follow the principles of shallow cutting, more bridges & culverts and less deep filling. (4) After the reform of railway investment and financing, there are more and more local investment projects, thus the interests and voices of local investment are of great importance on the determination of route and station layout. Under the premise of matching national network plan, not affecting the technical parameters and investment benefits of the project, the local investment opinions should be fully respected when determining the route and station layout, try to achieve a win-win cooperation and harmonious development. (5) The conclusions can be used as reference for similar design.

Research purposes: In order to analyze the lateral stability of suspended monorail vehicle when it passes through the curve. Based on the domestic suspended monorail system, the vehicle-line coupling dynamics model with 60 degrees of freedom is set up by using the multi-body dynamics software Universal Mechanism. Taking the car body and bolster as the main research objects, the variation characteristics of the lateral deflection angle of the vehicle under different damping device parameters are explored, such as lateral/vertical damper、air spring、swing damper. Research conclusions: (1) The variation of lateral and vertical damper damping and air spring horizontal/vertical damping have little inhibition on the body and bolster’s lateral swing of suspended monorail. (2) Reducing the horizontal stiffness of air spring is conductive to slowing down the vibration attenuation period of vehicle, while decreasing the vertical stiffness further increase this attenuation period. (3) If considering parallel steel spring at the swing damper, its increasing stiffness is beneficial to reduce the maximum lateral deflection angle of the body and bolster, while increasing damper is focused on reducing the lateral oscillation frequency. Therefore, the damping and stiffness parameters of swing damper should be considered comprehensively to improve the passenger comfort experience effectively. (4) The research results can provide some references for the suspension parameters optimization and line design of suspended monorail vehicles.

Research purposes: In the construction of tunnels under existing railways Subgrade or tunnel , the pipe roof support in advance is often used.At present, the engineering analogy method is often used to determine the parameters, so it is necessary to study the deformation l and design parameters of the pipe roof. Research conclusion：(1) The structural deformation of pipe shed consists of bending deformation of pipe shed and compression deformation of supporting structure. The formula for calculating the deformation is as follows: . (2)Except for the unsupported section, the influence of the length change of the other sections on the deformation of the pipe shed is relatively small, and deformation increase significantly with unsupported section increase, and the smaller stiffness, the greater increase; the deformation of pipe shed increase linearly with the increase of load; The deformation of pipe shed decreases with the increase of stiffness, and the longer unsupported section, the greater reduction range, when the stiffness of pipe shed is small, the increase of stiffness and deformation will decrease significantly. When the stiffness reaches the critical value, the increase of stiffness and deformation will not decrease significantly. (3) In order to reasonably select the diameter and length of pipe shed, the deformation control, investment and construction difficulty should be considered comprehensively.

Research purposes: Based on the principle of orthogonal test, the factors affecting the thermal environment of typical subway stations in winter are analyzed, and the order of the factors and the optimal operation scheme are obtained. It provides a theoretical basis for the thermal environment control of subway stations in northern China and guides the selection of platform edge doors and the formulation of operation strategies for subway stations in winter in northern China. Research conclusions: The research results show that: (1) The primary and secondary order of the factors affecting station hall temperature is: soil temperature (T_soil) > outdoor temperature (T_w) > the number of piston vent shaft (δ) > passenger flow rate (fv) > platform door opening area (s) > train cycle (tf), (2) The primary and secondary order of the factors affecting station platform temperature is: soil temperature (T_soil) > outdoor temperature (T_w) > passenger flow rate (fv) > train cycle (tf) > platform door opening area (s) > the number of piston vent shaft (δ), (3)When the single piston system is adopted, the average station temperature is the maximum and when the closed mode operation is adopted, the average station temperature is the lowest,(4) Compared with the platform bailout door(PBD), the platform screen door(PSD) is more effective to improve the station temperature in winter in northern China.

Abstract: Research purposes: In order to study the mechanical properties of the super-long span underground space structure and its roof steel structure in cold area, this paper takes He Dong Airport Station as an example, which is an air-rail transport hub combined with Yinchuan He Dong Airport Terminal. The underground structure of He Dong Airport Station has the largest span of 13m, the shallowest soil cover of 1m, and the length of the station is about 451m. It is located in the cold area, and its structure is greatly affected by the temperature change. Because the underground station has a large span, many openings and is located in the area of 8 degrees of fortification intensity, its seismic performance needs to be focused on. The problems of temperature, seismic resistance and steel structure are systematically studied. Research conclusions: 1) The temperature stress of underground station structure is caused by the temperature change of underground station. The temperature stress changes gradually from both ends of the station to the central part of the station, and the maximum stress appears in the central part of the station. 2) Temperature stress concentrates at beam-column joints, intersections of slabs and walls, and structural openings. Necessary structural and construction measures should be taken to reduce cracks. 3) Under the action of moderate earthquake, the maximum inter-story displacement ratio of the underground station is less than 1/550, and the structure is in the stage of elastic work, so the anti-seismic condition does not play a controlling role; under the action of large earthquake, the elastic-plastic inter-story displacement limit of Hedong Airport Station is less than 1/250, and the structure is in the stage of elastic-plastic work locally; 4) the inverted triangular steel truss structure is stable and suitable for large-scale construction. Cross-roof truss structure. The axially symmetrical spherical joints adopted in this design can effectively resist external loads and improve the overall stability of the steel frame, which can provide reference for similar projects. 5) Successful implementation of the station provides a basis for super-long and complex underground long-span structures, and has important reference value and guiding significance for the construction of railway hub stations and similar projects in the later period.

Research purpose: Subway construction is an important means of developing underground transportation using shallow burying method, with acceleration of the pace of urbanization. In order to study arching effect of shallow buried tunnel, this paper takes the construction of Qingdao Metro project as the research object. Vault carrying thickness can pushed by calculating of the surrounding rock pressure through the elastic analytical solution of complex variable function method and the analytical solution of surrounding rock stress and displacement. The arching effect presents in buried tunnel, through overburden load of tunnel arch can pushed by arch cover deformation. In this paper simulation analysis of arching effect of shallow buried tunnels by theoretical derivation and numerical simulation method，finally, combined with the actual measured data of a station for arching effect. Research conclusion: （1）The surrounding rock of the shallow buried tunnel can bear more than 80% of the load on the overlying stratum. It is proved that there is a significant self-arching effect in the shallow-buried and deep excavation large-span stations in hard rock strata, which needs to be considered in design and construction.（2）The hard rock shallow tunnel has arching effect under certain overburden thickness conditions, and the surrounding rock is subjected to most of the load, and the initial bearing is subjected to very little load. In summary, the existence of arching effect in shallow-buried large-span stations.

Research purposes: The Xining-Chengdu Railway is located in the northeastern margin of the Qinghai-Tibet Plateau, with complex geological conditions and extremely developed undesirable geology. It is also facing the challenges of high pressure gas reservoir for the first time,and water stability of red sandstone,a wide range of large deformation of soft rock and other special geological problems. Therefore, it is necessary to carry out targeted research to optimizing the route scheme and reduce the project risk. Research conclusions: (1) The main components of the high pressure gas reservoir is CO2 which formed from thermal decomposition of basement marble and controlled by nose-like uplift structure, thus the line scheme should avoid the uplift structure. (2) The results of water stability evaluation based on lithological and hydrological conditions show that the water stability of red sandstone strata in Cretaceous Minhe Formation and Tertiary Guide Formation is poor, where the routes should be bypassed or passed at a minimum distance. (3) Based on the initial in-situ stress, rock characteristics, groundwater and tunnel axis, the potential large deformation risk of soft rock is analyzed, and a best route scheme is optimized. The final recommended scheme is mainly slight to medium large deformation. (4) This study has reference significance for the survey, design and line selection of railways, highways and other projects with similar geological problems.

Research purposes: Fiber reinforced concrete (FRC) has rarely been reported in the anti-dislocation design of viscous-slip faults in tunnels. In order to improve the safety and stability of tunnel structure across viscous-slip fault, the anti-dislocation effect of plain concrete lining and different fiber reinforced concrete lining across viscous-slip fault is compared and analyzed by taking F1 viscous-slip fault section of a tunnel as the research background, and the appropriate anti-dislocation technology of fiber reinforced concrete lining of viscous-slip fault tunnel is put forward. Research conclusion: (1)the compressive strength of SBFRC cube is slightly lower than that of SFRC, and the flexural strength of SBFRC is slightly higher than that of SFRC With the same volume of fiber content. (2)The effect of stick-slip fault dislocation on hanging wall is larger than that of footwall. (3)The resisting dislocation effect of fiber reinforced concrete lining on the footwall of tunnel structure is better than that on hanging wall, the average resisting dislocation effect of SFRC secondary lining is 12.22%, and 15.81% for the SBFRC secondary lining. (4)The research results can provide a reference for the structural design and construction of the tunnel crossing stick-slip fault.

Abstract: Research purposes: Rail transit plays a backbone role in urban comprehensive transportation system. In order to meet the demand of the city’s multiplex development, more and more rail transit construction need to consider the disassembly of the 1 or more lines. Besides, line’s disassembling schemes have been an important area of research which in the design of rail transit. Based on the design of Ningbo-Fenghua intercity railway project, this paper analyzes the characteristics of the elevated line’s disassembly and the relevant problems in design, then puts forward three different kinds of transfer schemes combing with the forward requirements of its disassembly. It’ll be a reference for the study of the rail line’s disassembly by analyzing the characteristics of the different schemes. Research conclusions: 1)The design of the disassembly planning should be based on comprehensive considerations such as transfer convenience, operation conditions, difficulty of project implementation, sequence of construction, project scale and its impact on surrounding environment. 2) The disassembly time of Ningbo-Fenghua intercity railway is uncertain, Taking into account reducing the scale of recent reserved projects and the impact on road traffic, the scheme of independent station and transfer by passage is recommended. 3) The research results can provide the reference for the study of disassembling schemes of other rail transit lines．

Research Purpose: The interoperation requirement between the inner-city and the inter-city is appearing, aiming at National Railway CTCS and Urban rail interoperability CBTC signaling system, the paper studies the difference and the interoperation issue to explore the interoperation procedure between the two system. Research Achievement: (1)Concludes the requirement, structure and implementation difference between National Railway CTCS and Urban rail interoperability CBTC signaling system;(2)Proposes the interoperation schemes as car-born compatible, wayside compatible and equipment compatible method, compares and analyses these schemes;(3)Put forwards the short-term object which includes car-born compatible and signal aspect consistent, investigates primarily the long-term object of equipment compatible method including the modification direction and content of the interoperability system.

Abstract: Research purposes: In order to research the feasibility and application effects of the protecting measures on a new underpass cross the metro shield tunnels, two different protecting measures of a typical project were taken as an example. Finite element numerical analysis results on the application effects were compared, as well as the monitoring data of the recommended measures. Research conclusions:1）The measures which combined with reinforcing surrounding soil of the metro tunnels by cement mixing method and excavating foundation pit by core pulling method, is seem to reduce the uplifts of the metro shield tunnels in theory，but it's not very effective. 2）Due to the broken of soil structures during the reinforcement process，it can cause significant horizontal convergence actually. 3）Method of using pipe-roofs, anti-floating piles and jacking precast box-culvert, is more efficient at controlling tunnel deformation and shortening construction period.

Abstract: Research purposes: Tunnel deformation monitoring and measurement is an important means to judge the safety of construction and support, so the allowable deformation value is a key technical parameter in tunnel design and construction. But at present, the design of support parameters is mainly based on engineering analogy method. It is difficult to give the corresponding deformation monitoring control values for a specific support parameters in the design. Even if the support parameters are dynamically adjusted according to the monitoring values in the field, the rationality of the support parameters can not be evaluated intuitively. Based on the total safety factor design method, this paper presents the calculation method of field measurement control value and adjustment scheme of construction measures . Research conclusions: (1) The deformation value monitored in construction is actually the deformation value of support structure, so the allowable deformation value of support structure can be used as the control value of field monitoring. (2) The calculation method of allowable deformation value and ultimate deformation value of support structure based on total safety factor design method is proposed. Besides, deformation monitoring control values corresponding to the design safety factor can be obtained. (3) The method of judging the safety of field deformation monitoring values and the method of adjusting support parameters and support timing are put forward. (4) This study can provide ideas and methods for dynamic design of tunnels.

Abstract: Research purposes: Former study on diatomite focus on chemical product and architecture, etc. There is still no further research on engineering characters, such as compostion and structural features and their relationships to physical and mechanical properties. To provide a reference for similar soil study and constructionin in similar condition, we try to reveal the structure, ingredient and their engineering implication by laboratory and in-situ test together with comparing common rock-soil, as clay, mollisol and lutite. Research conclusions: Diatomite in Zhejiang is generally rich in clay minerals, high-content water, with poor permeability and extra large pore. Multilevel pore in the diatomite remains is the key point for diatomite to remain higher structural strength than normal type soil with high water content; Repeating wetting and drying cycle of white diatomite result in divide between the white and blue diatomite; Riching in organic material is the significant difference between black and white andblue diatomite; A warm, wet depositional environment and contemporaneous volcanism play a crucial role for the diatomite formation in Shengzhou, Zhejiang.

Research purpose: By the influence of temperature change, the tunnel lining in cold regions are easy to cracks. The authors analyzes the environmental effect of tunnel in cold regions, summarizes the frost-heaving mechanism of the tunnel structure, and propose the anti-freezing measures of tunnel structure based on investigation on some railway tunnel structure freezing cases in cold regions in China. The authors also study the applicability of the insulation layers of railway tunnel with its design method and construction technology, make clear the resistance frost technique of tunnel structure in cold regions for future study. Research conclusions: （1）The freezing damage of tunnel lining structure in cold regions can be divided into two types: surrounding rock with frost heave damage and structure defect damage. And the corresponding measures should be taken to control it. （2）The lining of tunnel in cold regions are easy to cracks by the temperature stress which is caused by negative temperature difference, and the structural measures such as deformation joint should be taken. （3）The insulation layer should be used carefully in railway tunnel in seasonal frozen soil regions. （4）It is necessary to further deepen the research on crack control technology and joint waterproofing of tunnel lining in cold regions.