Research conclusions: In order to ensure rationality and validity of a dewatering design, the dewatering design must consider engineering geological conditions, hydraulic geological conditions and foundation bracing system to select reasonable hydrological parameters and make analysis of seepage flow with three -dimensional seepage mode.l The dewatering should be conducted strictly according to the dewatering design scheme with immediate dewatering and dynamic control to reduce dewatering depth ofpressure -bearingwater foreffective controlling the subgrade subsidence around the foundation pitasmuch as possible and ensuring the railway traffic.

Research conclusions: In order to analyze the subsidence of roadbed caused by excavation of foundation ditch，the numerical model was set up，which is composed of two parts，including the vehicle—track—roadbed—ground coupling system and the roadbed—ground—ditch—supporting structure coupling system．It is shown that the depth．Support Method. and the load will induce the different sedimentation of the roadbed．The vertical dynamic displacement in the three cases is between 0．8 to 1．6 mm．and which come up to the standard．

Research conclusions: The monitoring result proved that the distance to the pilling area Was shorter and the effect of soil squeezing was bigger，the accumulated growth of super pore water pressure Was bigger．The depth WasS deeper，and the accumulated growth of super pore water pressure was bigger．By the monitoring of the super pore water pressure and the displacement of deep soil body，the construction speed and sequence were adjusted for the pile base construction．The soil squeezing of pipe pile Was obvious because the main direction of displacement was the reverse direction to the pilling．Therefore，before the placing of pile，the measure of deviation was taken to minimize the influence of the piling against to the existed pile．In the area where needs to control the soil body dispacement，the piling speed and the direction weFe strictly controlled，and at the same time，skip—piling technique was used to effectively reduce the soil squeezing by piling．

Research conclusions: The study results showed the integrality and homogeneity of concrete pile were rather perfect and there was no major quality defects like segregation．The majority of the compressive strength of concrete pile was between 28—33 MPa．and coe侬cient of variation of compressi。ve strength was only 0．14. and the static modulus of elasticity was 2．40×104 MPa．All these met the technical requirements．The artificial upper table for soil around the pile was between 0．08-0．2 m．and deformation of pile foundation in permafrost area was less than 10 mm，which satisfied the post— construction deformation demands for the ballasted deck piers．It was concluded the bridge foundation of Qinghai—Tibet Railway was stable．

Research conclusions: This analysis reveals：(1)The steel truss girder bridge main bar is mainly bearing the axial force，which is consistent with the design theory．(2)The effect of the spatial load transferring of the bridge is associated with the connection stiffness of the bars，the bar location and the load location，and to simplify the calculation of the load distribution between the two main trusses with the leverage method is safe．(3)Compared with the plane stress model，the stress of bottom chords calculated with the space beam element model is smaHer by 9．9％～16．4％，and the verification coefficient to compute statistics structure with the plane trussing model stipulated in the”Code for Inspection of Railway Bridges”only has the reference meaning．(4)Under the condition of main force combination，the actual stress of each test member is smaller than the design permission stress and has certain margin for safety．(5)The secondary stress of the member is proportional with the rigidity of the gusset plate and member．

Research conclusions: Based on the analysis of operating processes of JQ 900 series of bridge erecting machine with the finite element method，a dynamic model was established for the dangerous working condition of the bridge erecting machine．The dynamic model was simplified through the calculation and simulation of support stiffness of tire with the contact finite element method and energy method，and the calculation formula for natural frequency and corresponding vibrationl shape of bridge erecting machine were obtained．Compared with the calculated results of the finite element， the kinetic model Was verified．The new formula and corresponding vibration shape provide a theoretical basis for the dynamic optimal design of the beam structure of the bridge erecting machine．

Research conclusions: The verifying calculation is carried out separately to seepage field of the tunnel with finite differential geotechnical software package FLAC3D and Harr solution. By calculation comparison, the contour maps of the seepage field distribution made with the analytical solution, the definite differential geotechnical solution and Harr solution are gained respectively. By comparison, the correctness of the analytical solution to the seepage field distribution of deep buried tunnel is proved.

Research conclusions: Through comparison and choice of the protective schemes for the building around the shallow buried，the scheme of grouting reinforcement was proposed for the protection of buildings for the first time in this paper．Through the study and test results，the foundation grouting and trace grouting could effectively control the building settlement．Adopting the building protection scheme，the grouting parameters，uplifting value，uplifting rate and SO on should be adjusted．

Research conclusions: In today of the continuous development of tunnel，how to effectively control geological disasters in tunnel construction is the key element for ensuring the normal service of the tunnel．According to the influence factors on the tunnel construction，this paper discusses the measures for control of geological disasters in tunnel construction and points out the control of the geological disasters in tunnel construction is complex engineering and it needs the coordinations among the authorities concerned．The methods of TSP and high density resistivity are the effective ways to control the geological disasters．If the warning forecast is used，combining long—term forecast with short—term forecast，combining the control of the disaster on the upper part with the control of the disaster on lower part and combining the quantitative control with qualitative control are needed to guarantee the the forecast accuracy．In addition，it is necessary to strengthen the works of the blast control，informationalization construction and applications of new technologies and methods．

Research conclusions: The two—dimensional analysis show that there is a certain correlation between the stratum movement and stress release．The displacements of different points and their varying laws of the stress release rate are of obvious differences．Choosing the displacement at one area to describe the displacement release around the tunnel is incomplete，while using the volume loss rate of tunnel excavation to describe the displacement release around the tunnel is more complete．The study results also show that the stratum volume lOSS rate and stress release rate are of a linear relationship basically．This relationship can be as the references to determining the reasonable stress release rate and volume loss rate(displacement release rate)．

Research conclusions: From the comparison between the compress—resistant capacities of two specimens at the same age of two kinds of different grouting materials it was found out the corrosion—-resistant capacity of the slag—Portland cement Was much better than the Portland cement．The optimized grouting slurry Was used to reinforce the ground of the service tunnel of Jiaozhou Bay in Qingdao，obtaining a good reinforcement result．

Research conclusions: The analysis model of sheafing and compressing resistance for double—layer lining was used to analyze the characteristics of the internal force properties of the structure under three representative kinds of conditions．The result proved that adding secondary lining might increase the moment and decrease the axial force of segment lining，and this effect Was especially obvious when water leakage occurred in the segment lining．Compared with segment lining，the secondary lining only plays an assistant role in the load bearing．With adding the secondary lining，the entire load—bearing of the double—layered lining Was not more reasonable．The ideal combined beating effect of double—layered liner only happened under conditions of specific load，ground parameters and structure parameters．The secondary lining could mainly bear the load when the segment lining completely failed and it played an assistant t role in load bearing．

Research conclusions: Application of this model can quantitatively evaluate the lining health of railway tunnel and objectively analyze the impact factors and levels of the most important desease．The application shows the model can be used for the similar works．

Research conclusions: The neural networks can effectively predict the deformation and stability of the deep foundation pit in advance．and the stability based on which a judgement call be made on the stability of the deep excavation．The prediction value is much more closed to the measured value by using time series as an input layer．This shows the time series method can reflect the internal non—linear relation between the deformation of bracing structure of foundation pit and the time．In practice，the transfer of construction processing sequence can induce a sudden change of the measured value of the deformation．However，the big deviation of the predicted value from the mesaured value may result from ineffective training due to the small sample range of neural networks．

Research conclusions: The research shows as the external insulation level of the catenary of electrified railway is low，the insulator on support post is easy to flash over continuously under the over voltage of lighting．The attention should be paid to this when making analysis of the lighting—resistance capacity of the catenary and taking measures for lighting protection，otherwise，the big error will be brought out．The arrester is not suitable for the distributed lighting protection way in broad area，but it can obtain good effect for the lighting concentrated area with installation of it coneentratively.

Research conclusions: During construction of Xunlimen Station，the monitored data on settlement showed the construction of Xunlimen Station may much affect the operation of the light railway．Through analysis of the relative position of the deep foundation pit to the bridge pier of light rail and the distribution of the soil layer，the construction scheme was optimized and the additional monitoring points are added．With these measures，the settlements of the bridge pier trended to stable and the absolute settlement values and the differential settlement values were effectively controlled in the next construction．

Research conclusions: During the construction，the uncontrolled release of shallow gas would seriously disturb the soil layer．The distablization of the trench wall or hole wall and the upheaving of foundation ditch might happen because of the high gas pressure．Moreover．there was the hidden peril of safety accident when shielding Was conducted across the gas soil layer．So，the measures like controlled release of the shallow gas had to be taken during the construction to prevent the disasters caused by the shallow gas．

Research conclusions: For construction of the connecting passage in water-enriched sand bed, the artificial ground freezing method is a prior construction method featured with high reliability and no pollution of groundwater and ground. Moreover, in order to ensure the successful and safe application of the artificial ground freezing method, the duct piece at the tunnel portal of the connecting passage should be designed specially. In order to reduce the impact of expansive soil on the tunnel, the internal support should be installed in the tunnel to effectively control the tunnel deformation. The special measures should be taken in the process of freezing, such as installation of safe door to prevent the appearance of accident. In addition, to install pressure-releasing holes and use heat -cycling and trace grouting methods are effective.

Research conclusions: Relying on the financial indexes of the bidding enterprise and determination the weight with entropy weight decision—making method．and taking fuzzy evaluation model for project risk as a rule，a complete set of models of integrating theory with practice are established to solve the problems．This method wa$examined in the real Construction practice．The result showed this method could solve the problems in the previous bidding and with this method not only could the the bidding cost of the highway construction be cut，but also it could make the bidding more fair and scientific．

Research conclusions: The transportation equity indexes are the main elements in evaluation of the transportation equity, butchoice ofevaluation indexes are ofblindness and randomness atpresen.t By studying, the definition of the transportation equity is offered on the base of capacity -supply equity. Meanwhile, the eight basic principles forchoosing the transportation equity indexes are presented, namely, relativity, clear definition, consistency, correct incentive, flexibility, objectivity, practicality and comparability. The properworking process and requested information for choosing the indexes are also given ou.t From the study on chossing the indexeswithWilson entropy mode,l it is concluded by following these principles, requested information and working process, the selected indexes can be examined, and the new reasonable indexes can be selected forevaluation of the transportation equity evaluation.

Research conclusions：(1)The proprietor must play the core and leading role in the design management．(2)The design unit should bear all the responsibility for the design quality．(3)The major technical programs should be accredited by professional team．(4)For the total price contract，more attention should be paid to ensuring the construction security and quality in the engineering design and for the unit price contract，attention should be paid to examining the design．(5)It is necessary to study more appropriate field coordinated system of design corporation．(6)Implementation of the”Design Supervision”system is the inevitable trend of social and economic development．