Research conclusions: The experimental study results show that the glass foam revetment is better than the sward revetment in insulated during the experimental period, which can reduce the seasonable thawing depth and benefit the stability of the slope. However, the obvious frozen deformation can appear to the glass form revetment in frozen period, resulting in its breaking and crack under external force. As the glass foam is easy to be weathered and weak in non - deformability and adaptability, it is unsuitable for being used in permafrost region. As the thawing depth of sward，revetment is deeper than that of the glass foam revetment and most parts of sward revetment are flat with small deformation and good adaptability, the sward revetment is suitable forbeing used in permafrost region.

Research conclusions: Construction of the Qinghai—Tibet Railway changed the original condition of the frozen soil permafrost along the railway and water—heat environment around the embankment of railway．At the same time，the annual fluctuation and perennial fluctuation of the air temperature influence the engineering status of the embankment． This paper analyzes the main influence factors on the stability of the embankment on slope in permafrost regions Mong Qinghai—Tibet railway，such as water，ground temperature，frozen ground type and direction and degree of the slope，and gives the negative influence of these factors on the roadbed．

Research conclusions: The loess slope can be divided into 6 types：neo—loess slope，old+neo—loess slope，old loess slope，the neo—loess+bedrock slope，the old loess+neo—loess+bedrock slope and the old loess+bedrock slope．The styles，characteristics，formation mechanism and the hazard of deformation failure of these six types of slope are analyzed，and the stability evaluation criteria for them are worked out．Through the analyses of the stability of loess slope Mong the Taiyuan—Zhongwei Railway，the control measures for the disaster of loess slope are suggested with the certain significance to the loess slope along railway line．

Research conclusions: The changes of rainfall infiltration and groundwater level change make the rapid change of porewater pressure with the different change laws in different areas．At the initial stage of rainfall，there is a most notable variation of pore water pressure．Matrix suction of landslide changes with the change of rainfall．On later stage of rainfall，the most matrix suction vanishes，which is very harmful to the stability of slope．The water level change，rainfall intensity and rainfall have much influences on the stability of landslide，among them the comprehensive influences of rainfall intensity and water level change are the most prominent．In the circumstances of strong rainfall and underground water level going up and down，the stability coefficient of slope is reduced sharply．

Research conclusions: construction of the subgrade of high—speed railway．Research conclusions：Through the experimental research in the experimental section，static load test and data analyses，the method for testing the bearing capacity of CFG single pile and the single pile composite foundation is summed up．It shows the static load test can test the bearing capacity of CFG single pile and the single pile composite foundation．The test results can provide the basis for the improvement of CFG single pile and the single pile composite foundation to reinforce the soft subgrade and provide the guide of widely using it to to reinforce the soft subgrade of high—speed railway．

Research conclusions: The test results show that pile—-soil stress ratio becomes large with increase of height of filling soil，the law of pile—soil stress obtained with the Germany norm is in line with the actual situation and the calculation results meet the requirement of computing accuracy，thus the Germany nolTn can be used for calculating the pile—soil stress．

Research conclusions: The subgrade filling，construction—post subsidence evaluation，ballastless track laying and observation of them for over one year show if the treatment principle for composite foundation is well followed and the construction quality is effectively controlled for the whole construction process，the design requirements Can be fully satisfied with the small construction—post subsidence of subgrade as the bridge and culvert，forming a perfect configuration of railroad，bridge and tunnel．

Research conclusions: The system make full USe of the terrain and high—definition digital images and other basic geographic information resources provided by the Digital Earth Software to establish a three—dimensional alignment platform and it has been successfully applied in many projects，such as Ankang—Zhangjiajie and Zhengzhou—Wanzhou railways．The applications show that the system has following features：(1)The real—time digital terrain and image data are picked up from Google Earth．(2)The planar alignment is realized in Google Earth with KML technology of Google Earth，which Goosle Earth becoming a digital earth—based three—dimensional spatial platform for railway route selection．(3)A logging and query system is established for the information on the railways and natural environment along the railway．(4)The plane，vertical section，cross—sectional design models for a new railway line arc established under the traditional AutoCAD platform，which can meet various diamonds of the fine design railway to overcome the problem of optimization of vertical section．(5)The three—dimensional visualization of railway design outcome is realized in Google Earth platform．

Research conclusions: Through research and comparison analysis，the main technical parameters for 250 km／h railway line for mixed passenger and freight traffic are as follows：the minimum curve radius length is respectively 5 200 m in ordinary section and 4 500 m in difficult section，and the minimum length of tangent between Curves and circular curves respectively is 200 m in ordinary section．1 50 m in difficult section and 1 25 m in extremely difficult section．The relative lengths of transition Curves on different plains can be as the reference in design．

Research conclusions: The major types of strong wind along railway lines in China are as follows：cold wave. short time thunderstorm and typhoon．It is necessary for the strong wind alarm systems to have different modes of forecasting instantaneous wind velocity according to different landforms，geomorphology and strong wind patterns．The landform factor K is obtained by calculating the ratio of fluid simulation results to experimental data．The curve of traffic management of high—speed train is plotted under strong wind weather．Information on reasonable limited traffic speed is shown to train command and control systems by using this curve．This study is great important to reduce the influence And danger degree of strong wind on the safety of hish—speed train and ensuring the maximum traffic efficiency of train．

Research conclusions: The analysis resultsofdynamic response on the slab track show that the criticalvelocitiesexistin the track structure. The dynamic displacements of the rai,l slab and concrete base to track direction become the biggest when train runs at even speed. Meanwhile, peak value of dynamic displacement occurs at different speed and acceleration undervariable speed. The peak value ofdynamic displace stillexists at the differentspeed and acceleration when the train speed slows down, and the dynamic displacement of each structure will reduce at increasing positive acceleration and reducing negative acceleration and vice versa.

Research conclusions: According to real construction condition of Wuhan—Guangzhou PDL and with consideration of the imported machine from Germany and localization of the machine in China，the analyses are made for the construction machines from the fields of construction quality and efficiency，and the ideas are expressed on the complete construction machines for guaranteeing the construction quality and efficiency．Through absorption of the foreign machines，the construction practice of CRTS I Ballastless Track on Wuhan—Guangzhou PDL shows the all construction machines for CRTS I Ballastless Track can be manufactured by China except the machine for fine adjustment．

Research conclusions: Through emulation analysis and calculation，the movable mould can pass the span in advance and the time of erecting girder for one span with movable mould Call be shortened to 1 1 days from 1 8 days by tensioning partial stress to bear the weights of girder and movable mould when the poured concrete gets to 80％of designed strength after 3 or 4 days of concreting the girder．So the construction process is speeded up and the requirement of construction schedule can be met．

Research conclusions: Based on the research and calculation analysis，the temperature feature and change regularity of massive concrete were revealed and the standard for controlling temperature of massive concrete Was proposed．The temperature differences within the fixed range between inside and outside the reinforcement pile cap of main pier，pier shafts，No．0 pylons and segments of box beams call be guaranteed by adopting the corresponding temperature control measures，such as adopting the reasonable concrete matching ratio，proper pouring by layer and effective temperature maintenance．

Research conclusions: The results show：(1)The differences of the static response in displacement of the tunnel and axial stress of support component are fairly small as the crossing span increases from 2 000 m to 4 000 m，but the dynamic response increase notably．(2)The static response of tunnel with an elliptical cross section is extreme smaller than that of tunnel with a circular cross section and the dynamic response of former is extreme bigger than that of the latter．(3)The response of SFTwith mooring tether anchorage is extreme smaller than that of sFr with tension leg anchorage．

Research conclusions: Using directional churning jet pile to reinforce the soil outside the tunnel to the fixed direction and pile position has obvious effects on forming arch lining，stabilizing the working face and controlling the ground subsidence when excavation of the outside configuration of the tunnel．Compared with the other methods，the directional churning jet pile is better in reinforcement in advance and can guarantee the safety of tunnel construction and underground pipelines．So it can be used in similar construction．

Research conclusions: Using pipe roof construction technology decreases the crown settlement and ground settlement．This illuminates that using stratum—structure method to calculate the shallow pipe roof suppofl is reasonable．All of the arrangement area，space in the circumferential direction and the diffused radius of grout for the pipe roof construction have the optimal values．If the design parameters exceed the optimal values．the crown settlement will converge quickly．So increasing the design parameters blindly call not improve the reliability of the tunnel structure．

Research conclusions: There must be the following requirements for getting the accurate results of geological prediction：(1)The geological survey and investigation should be done on the site for geological structure and unfavorable geological body carefully，the quantitative prediction should be given with all prospecting methods and they should be verified each other．First of all．the accurate site surveyed data should be obtained when the prospecting method is used to survey．(2)The person for data processing should have the rich knowledge on the prospecting to correctly identify all numerical values of the parameters during the data processing．(3)The interpreter should eliminate the multi—interpreter of the prospecting result with rich geological knowledge when doing interpretation．

Research conclusions: In this paper，taking construction of Shiqiaotou Tunnel on the Longyan to Xiamen railway as all example，a series of influencing Actors on the ground deformation and stability of ground buildings when construction of shallow buried tunnel are systematically analyzed，including over excavation of tunnel，reserved deformation volume and soil squeezing in working face．The research results show that buildings above DK 3+200 adjacent to Shiqiaotou Tunnel are unstable because ground loss and ground deformation induced by ground loss when the tunnel is normally constructed．

Research conclusions: The monitoring measurement has the characteristics of the effectiveness for fixed time，continuity and protracted nature．The person in charge of implement of monitoring measurement must well know the key points and management program for implement of monitoring measurement and work out the operational guide book or detailed rules or regulations for monitoring measurement with quantitative indexes fits the basis to instruct the monitoring measurement work．During the monitoring measurement，the measured data should be processed and analyzed and data information should be given back in time．The data should be processed and analyzed in accordante with the observation of the surrounding wall and its support for overall identification and dynamic management．The data information should be given back to the construction enterprise in accordance with the grade of shift management for instructing the construction organization and arrangement．Giving monitoring measurement information back is the weak point in implement of monitoring measurement，but it is the controlled link．The monitoring measurement is one of important technical measures for prevention of tunnel collapse and control of the deformation of surrounding wall and it is also the important part in management，which should be brought into the management work．

Research conclusions: It is concluded from the experiment that as there is no optimal blending ratio，the unconfined compressive strength of cement modified soft soil increases with the increase of blending amount of cement，the cement modified soft rock has good property of water stability and the unconfined compressive strength can not reach at the max value at the optimal water content under the condition of equal compactness，and the maintenance is needed in the process of filling modified soil．

Research conclusions: By doing the research，the especial concrete for the railway in permafrost region Was developed，which provided the good foundation for the similar works．The applicable result showed this especial concrete could meet the construction diamond and the applicable requirement．

Research conclusions: China large—sized construction enterprises should learn from the advanced experience of the international well—known enterprises and set up the modelTl management concept on social responsibility so as to establish the management mode for fulfilling social responsibility，improve the governing structure，fulfill responsibility and enhance the management level of social responsibility for providing the perfect foundation to promote the healthy and sustainable development．