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2022 Vol. 39, No. 10
Published: 2022-10-15
Main Line: Survey and Design
Main Line: Engineering Geology and Subgrade
Main Line: Railway and Rail
Terminal,Station yard and Building
Research on Technical Standards and Specifications
Main Line: Bridge Engineering
Main Line: Tunnel Engineering
Main Line: Electrification Engineering
Engineering Materials
 
       Main Line: Survey and Design
1 Research on the Main Technical Scheme of Proposed Laos-Thailand Railway Connecting Line
JIANG Yalei, SUN Haifu
Research purposes:The proposed Laos-Thailand Railway Connecting Line is the key project of "the last kilometer" to connect the China-Laos Railway and China-Thailand Cooperation Railway and the key link to form the transportation capacity of the middle passage of the Trans-Asian Railway, and it is of great significance to promote the cooperation and development of regional countries and benefit the people in the surrounding areas. However, subject to the construction progress of Laos-Thailand Railway Connecting Line, the transportation capacity of the middle channel of the Trans-Asian Railway has not yet been formed, which has also been unfavorable to the transportation benefit of the China-Laos Railway. This paper makes a systematic study on the function positioning, passenger and freight volume, main railway technical standards, customs clearance mode, alignment, transshipment scheme, new Mekong River Railway Bridge scheme, the operation control model of cross-border trains, etc.
Research conclusions:(1) It is recommended to adopt Chinese Standard gauge railway system, and the number of main lines shall be single track with reserving double tracks. (2) It is suggested that the "border control in separate locations" customs clearance mode and "transshipment in both sides" are adopted. (3) It is suggested that a new Mekong River Bridge is set at about 30 m downstream far from the existing bridge, and the piers of the new bridge are aligned with the existing piers, and the scales of new bridge are three tracks, which are single-track for meter gauge railway and double-tracks for standard gauge railway. (4) The cross-border operation of passenger trains automatically switches between CTCS-2 and CTCS-0 in the section, and the cross-border freight train maintains the combination mode of locomotive signal and train operation monitoring device as same as China-Laos Railway. (5) The research results have reference value for the construction of newly-built cross-border railway.
2022 Vol. 39 (10): 1-6 [Abstract] ( 4138 ) HTML (1 KB)  PDF  (815 KB)  ( 2019 )
7 Research on the Overall Design and Key Technology of Hangzhou Bay Cross-sea Railway Bridge
ZHANG Jian
Research purposes:Hangzhou Bay Bridge of the Nantong-Ningbo High-speed Railway will be the world's longest high-speed railway cross-sea bridge with the highest construction standard. The construction conditions are complex, and there are few engineering experiences available for reference at home and abroad, and the engineering construction will face enormous difficulties and challenges. Based on the characteristics of the project, the overall design idea of ultra-long-distance sea-crossing bridges is proposed, and the typical key technologies such as laying of ballastless tracks for 450 m-class long-span cable-stayed bridges, the seamless line of 80 m-span ultra-long-connected concrete continuous beams, and intensive arrangement of four electric/electronic systems, emergency rescue, operation and maintenance of the ultra-long-distance sea-crossing railway bridges are studied, to provide a basis for project decision-making, and also provide reference for other cross-sea railway projects.
Research conclusions:(1) It is appropriate to choose the Haiyan West Passage to cross Hangzhou Bay as a bridge and build a double-track railway bridge. (2) The three waterway bridges of the Hangzhou Bay Sea-Crossing Bridge should be laid with ballastless tracks, and the whole bridge has no speed limit. (3) The ultra-long-distance approach bridge should adopt the 80 m-span ultra-long concrete continuous beam seamless line, and set up the rail expansion regulator. (4) The four electric/electronic systems of the ultra-long-distance cross-sea railway bridge should be arranged intensively, and the offshore four-electrical platform and pier should be arranged. (5) Emergency rescue stations should be set up for ultra-long-distance sea-crossing bridges, and centralized rescue should be combined with random rescue. (6) The ultra-long-distance cross-sea railway bridge should reasonably arrange the operation and maintenance channel according to the needs of public works, electricity, and power supply operation and maintenance.
2022 Vol. 39 (10): 7-12 [Abstract] ( 4037 ) HTML (1 KB)  PDF  (1287 KB)  ( 2013 )
       Main Line: Engineering Geology and Subgrade
13 Analysis of the Sedimentary Characteristics and Engineering Geological Characteristics of Dammed Lake Deposits of Jianzhu Bridge
DENG Rui, LAI Qingyong, ZHANG Guangze, CUI Jianhong
Research purposes:Dammed lake deposit is a common Quaternary lacustrine deposits stratum in mountainous rivers in Southwest China. On the basis of geological survey, this paper expounds the sedimentary environment characteristics of Jianzhu bridge, analyzes the engineering geological characteristics of dammed lake deposits and the engineering geological problems faced by the bridge, through comprehensive survey methods such as exploration, geophysical exploration, in-situ test and laboratory test, in order to provide accurate basic data for design.
Research conclusions:(1) The debris flow accumulation body of Jianzhu is the location of dam site. (2) The dammed lake deposit is mainly dark soft plastic silty clay, and the two-color rhythmic lamina is not obvious. There is a long dry climate period in the sedimentary environment. (3) The sediment particles size and thickness from the downstream to the upstream of the damming area are gradually increasing, and the maximum thickness of dammed lake deposit is about 35 m, and the thickness of single sedimentary rhythmic layer is 15 ~ 26 mm. It is speculated that the deposition time is more than 500 years. (4) Based on the analysis of the results of in-situ test and laboratory test, the relevant physical and mechanical indexes of sediment are obtained for design reference. (5) Weak foundation, sand liquefaction and potential barrier dam are the main engineering geological problems of the bridge. (6) The research results can provide reference for improving railway route selection and engineering protection in dammed lake deposition area.
2022 Vol. 39 (10): 13-18 [Abstract] ( 3969 ) HTML (1 KB)  PDF  (1131 KB)  ( 1900 )
19 Research on the Method of Obtaining In-situ Shear Strength Parameters of Fragile Rock Stratum
JIA Zheqiang, WANG Dong, REN Li, ZHANG Guangze, LI Jiayu, YUAN Dong
Research purposes:In engineering practice, fragile rock layers that cannot be cored, such as fully / strongly weathered rock mass, broken rock mass strongly affected by structure and soft rock, are often encountered, so it is difficult to measure the strength parameters of rock layers. It is urgent to develop in-situ testing methods suitable for the mechanical parameters of such fragile and difficult to obtain cored rock layers.
Research conclusions:(1) The key points of rock and soil drilling in-situ shear technology are combed. According to the pressure range and application scenario of rock and soil in-situ shear technology and equipment, the methods and steps to obtain the strength parameters of fragile strata are put forward. (2) According to the soft and hard degree of rock, weathering degree and rock fragmentation degree, the strength parameters of fragile rock stratum under different conditions are given according to the principle of low, and the applicable drilling in-situ shear technology and equipment selection suggestions are given. (3) It is applied in typical fragile rock strata such as strongly weathered granite, dolomite with joint fissure development and granite seriously affected by structure. The rock mass parameters obtained are in line with the empirical value or the range recommended by the code. (4) The research results can provide reference for the acquisition of in-situ parameters of other fragile strata.
2022 Vol. 39 (10): 19-23 [Abstract] ( 3984 ) HTML (1 KB)  PDF  (970 KB)  ( 1951 )
24 Application of Multi-span Continuous Beam Model in the Bearing Plate Design of Pile-blank Subgrade
GUO Shuaijie
Research purposes:Pile-blank subgrade is widely used in actual application scenarios, such as high-speed railway, heavy haul railway, side widening, station subgrade and road-bridge transition section, and has the technical characteristics of light weight, strong bearing capacity and reliable structure. However, its technical design still seriously depends on empirical method and simulation analysis. In order to obtain the analytical solution for the internal force distribution of bearing plate, multi-span continuous beam model was applied in the condition of pile-soil-plate joint action to determine the distribution characteristics of internal force and deflection deformation in transverse and longitudinal direction.
Research conclusions:(1) Upper load is mainly transmitted to the pile top through bearing plate, and the bearing plated deformation is generally no more than 0.5 mm, and 1.0-meter-thick bearing plate has sufficient section stiffness during general design conditions, which can meet the general design conditions. (2) The bidirectional driving is the most unfavorable load factor in latitudinal direction, and the negative bending moment at pile top is much higher than the one at the span middle. (3) Internal force distribution in longitudinal direction is more complex, and the internal force and deformation at the side span are much higher than that at the middle span, so unequal pile layout in longitudinal direction is more reasonable. (4) The research results can be applied in the bearing plate design and reinforcement calculation for pile-blank subgrade structure.
2022 Vol. 39 (10): 24-29 [Abstract] ( 3996 ) HTML (1 KB)  PDF  (813 KB)  ( 1938 )
30 The 3D Advance Geological Prediction Method Based on Shear Wave and Its Application
CAI Sheng
Research purposes:Because that most of the advanced geological prediction of tunnel seismic reflection method is based on 2D prediction and the accuracy is not high, an effective observation method of advanced geological prediction of three-dimensional seismic reflection is proposed. On this basis, a complete set of technology research on data processing and imaging is carried out, and its feasibility and reliability are verified through numerical simulation and physical experiments, which is effectively applied to the production of advanced geological prediction of railway tunnel.
Research conclusions:(1) Based on the basic theory of elastic wave, a three-dimensional seismic wave advance geological prediction observation system based on shear wave is proposed. Compared with the traditional P-wave prediction method, it has higher resolution and is more sensitive to water body. (2) The migration imaging method based on Kirchhoff integral is realized, which uses the energy superposition criterion for three-dimensional velocity scanning, and uses the fast marching method for travel time calculation, which is not limited by the observation system, has high calculation efficiency, and do not need a very accurate velocity model. (3) The finite difference numerical simulation of three-dimensional seismic wave field of tunnel is realized, and the typical adverse geological models such as lithologic interface with different dip angles, faults with different thickness and karst caves with different diameters are established, and their three-dimensional imaging characteristics are analyzed and summarized. (4) Through the physical model and application experiment, the method presented in this paper is feasible and reliable, and can be popularized and applied in tunnel advanced geological prediction.
2022 Vol. 39 (10): 30-36 [Abstract] ( 3296 ) HTML (1 KB)  PDF  (1388 KB)  ( 1905 )
       Main Line: Railway and Rail
37 Research on the Fine Adjustment System of New Track Structure of High-speed Maglev at 600 km/h
WANG Yukun, XU Lingyan, XU Peng, ZANG Chuanzhen
Research purposes:To ensure that the high-speed maglev train has good running safety and comfort when running on long trunk lines, the track smoothness has extremely strict requirements. Therefore, it is necessary to separate the track structure that provides high smoothness from the bridge that provides support, to significantly reduce the manufacturing and construction difficulties. It is necessary to study the new track structure form, and then develop the new fine adjustment technology based on the characteristics of the track structure, so as to provide an effective way to achieve and maintain the high smoothness of the track system.
Research conclusions:(1) A new type of high-speed maglev track structure with track plates laid on the laminated beam or box beam is proposed, which only needs to ensure the high-precision manufacturing and fine adjustment of the track plates, thus avoiding the overall high-precision requirements of the track beam. (2) A set of new track structure fine adjustment system of high-speed maglev has been formed. It mainly includes magnetic suction fine adjustment prism, fine adjustment software to realize the conversion between the positioning point of track plate and the spatial position of fine adjustment prism, fine adjustment claw integrating three-dimensional fine adjustment and fixing of track plate, connection and support device between fine adjustment claw, track plate and bearing beam. It can solve the key problems of realizing high-speed maglev fine adjustment engineering. (3) The research results of the new track fine adjustment technology of high-speed maglev can provide reference for the construction and operation of high-speed maglev project.
2022 Vol. 39 (10): 37-41 [Abstract] ( 3995 ) HTML (1 KB)  PDF  (1075 KB)  ( 1920 )
       Main Line: Bridge Engineering
42 Overall Design of Bridge of Qianjiang-Zhangjiajie-Changde Railway
ZHANG Jingli
Research purposes:The terrain and geological conditions along the Qianjiang-Zhangjiajie-Changde railway are extremely complex, the soluble rock is widely distributed, and the environmental protection requirements are high. In order to reduce the risk of the construction of karst section, a high line plan is adopted. This paper systematically summarizes the characteristics of bridge engineering under karst geological conditions in complex mountainous areas, studies and gives the principles of bridge structure selection and foundation treatment measures in karst areas, analyzes and summarizes the technical characteristics of two extradosed cable-stayed bridges, and puts forward an economic and reasonable bridge selection for similar bridges.
Research conclusions:(1) The geological conditions of railway in karst mountainous areas are complex, and the selection of bridge structure should be based on the principle of reasonable crossing and effective avoidance. (2) Different measures should be taken to deal with karst caves according to their distribution characteristics. (3) Extradosed cable-stayed bridge has large structural stiffness and excellent dynamic characteristics. Cable stiffening can effectively control the creep deformation of concrete structure, which can be used as the first choice for railway bridges with the same condition. (4) The research results can provide reference for railway bridge design in complex mountainous and karst areas.
2022 Vol. 39 (10): 42-46 [Abstract] ( 4053 ) HTML (1 KB)  PDF  (551 KB)  ( 1984 )
47 Experimental Research on the Characteristics of Shallow Layered Soft Rock Tunnel-type Anchorage in Deep Cutting
QIAO Leitao, KANG Wei, WEN Qiang
Research purposes:The deformation characteristics and bearing mechanism of the interaction between anchor plug body and surrounding rock of shallow layered soft rock tunnel-type anchorage are complex, and it is difficult to analyze and study with specifications or engineering analogies. In order to study the deformation law, failure characteristics and bearing characteristics of tunnel-type anchorages, the deformation characteristics and bearing capacity safety factor of tunnel-type anchorages are determined through on-site 1 ∶10 scale model tests, and the effects of soft rock, shallow burial, bedding plane and other factors on tunnel-type anchorages are explored. Finally, the safety and stability of tunnel-type anchorages are evaluated.
Research conclusions:(1) The deformation of the tunnel-type anchorage occurs from the back anchorage surface and attenuates to surrounding rock under all levels of loads. And the deformation of the anchorage plug and the surrounding rock on the left and right sides presents a symmetrical double hump shape. (2) Under the design load, the deformation of the anchorage plug is the largest, and the maximum deformation is 0.054 mm, and the predicted maximum deformation of the prototype tunnel-type anchorage is about 0.5 mm. (3) The ultimate bearing capacity of the tunnel-type anchorage reaches 18 times of the design load. Under the ultimate load, the anchorage plug carries the shallow buried rock mass directly above to have the inclined upward arch failure. The fracture surface comes from the bedding plane original crack to expand and the failure range exceeds 4 times the tunnel diameter. (4) All these show that the deformation limit and the safety factor of surrounding rock meet the requirements of the specification and tunnel-type anchorage is safe and stable. (5) The research results can provide a reliable basis for the safety evaluation of the tunnel-type anchorage system of Youxi Yangtze River Bridge, and also provide technical reference for related projects.
2022 Vol. 39 (10): 47-52 [Abstract] ( 3242 ) HTML (1 KB)  PDF  (1980 KB)  ( 1869 )
53 Research on the Causes and Preventive Measures of Shallow Defects of Cast-in-place Pile
CHANG Juyou, WANG Chen, WANG Zhengrong, HAO Lingxu, LIAO Zhong, YANG Hu
Research purposes:According to 7.3.3 of Q/CR 9212-2015 in Technical Specification for Bored Pile Works of Railway Bridge Construction, the height of over-pouring concrete at the design elevation of pile top should be 0.5～1.0 m, in order to increase the pressure to ensure the integrity of the pile at the design elevation at the top of the pile. The defects in the shallow part of the pile at the design elevation at the top of the pile can be detected on the spot, and the compressive strength of the core sample with a drilling depth of 0.5 m is not satisfied with the design requirements. The cause and how to prevent the defects should be studied.
Research conclusions:(1) The height of over-pouring concrete at the design elevation of pile top shall be 2 ~ 3 m. (2) The slump of concrete shall be controlled within 180 ~ 220 mm. (3) During pile cutting, a circle of the outer edge at the design elevation of the pile top shall be cut in a ring, the exposed part of the design elevation of the pile top shall be provided with coarse aggregate with the maximum particle size, and the strength of the core sample with a drilling depth of 0.5 m shall meet the design requirements. (4) The buried depth of concrete conduit shall not be less than 3 m, and the conduit shall be centered when pouring concrete. After the short cage is used for hole dredging, the hole shall be cleaned again, and the sediment thickness at the bottom of the end bearing pile shall not be greater than 50 mm. (5) The research results can provide reference for improving the construction quality of bridge bored pile in railway, highway and other fields.
2022 Vol. 39 (10): 53-58 [Abstract] ( 3250 ) HTML (1 KB)  PDF  (967 KB)  ( 1957 )
       Main Line: Tunnel Engineering
59 Research on the Large Deformation of Soft Rock in Deep Tunnel Based on Rough Set and AHP
MA Bangchuang, ZHANG Zhiliang, ZHAO Wen, WANG Peng, CHEN Xingqiang, LUO Feng
Research purposes:Large deformation of soft rock is the main engineering geological problem encountered in the construction of deep buried railway tunnels. Based on the construction data of Lanzhou-Chongqing railway, this paper analyzes the main influencing factors controlling the large deformation level of soft rock, determines its subjective and objective weight, establishes the prediction model of large deformation of soft rock and carries out calculation verification.
Research conclusions:(1) Lithology, rock integrity, layer thickness, ground stress state, relationship between rock strata strike and tunnel, groundwater and rock strata dip angle are the main factors affecting large deformation of soft rock. (2) In the subjective and objective analysis methods of rough set and Analytic Hierarchy Process (AHP), the weights of rock integrity degree, layer thickness and ground stress state are significantly higher, while the other factors are relatively minor. (3) The calculation results show that the AHP structural model has a high matching degree in Hadapu tunnel of Lanzhou-Chongqing railway. (4) The research result can provide support for similar railway geological line selection, risk assessment and engineering design, and provide a new idea for classification and prediction of large deformation of tunnel surrounding rock.
2022 Vol. 39 (10): 59-64 [Abstract] ( 3262 ) HTML (1 KB)  PDF  (427 KB)  ( 1934 )
65 Research on the Evaluation Method of Waterproof Performance of Elastic Sealing Gasket for Segment Joint
XIAO Mingqing, ZHANG Chaoyong, XUE Guangqiao, YU Xiongbing
Research purposes:At present, the waterproof performance of gaskets is mainly evaluated by the average contact pressure and effective contact stress, and the influence of uneven contact surface of sealing gasket and micro leakage hole is not considered, which results in great differences between numerical simulation and experimental results. In order to improve the evaluation method of sealing gasket waterproof performance, and establish quantitative evaluation indexes, the model of effective total leakage rate of gasket is established in this paper. Through numerical analysis and waterproof test, it is proved that the proposed effective total leakage rate index is reasonable as the evaluation method of sealing gasket waterproof performance.
Research conclusions:(1) The effective total leakage rate can be used as an important indicator for evaluating the waterproof performance of the gasket. (2) Due to the uneven contact surface of the gasket and the existence of micro leakage hole, the design of the gasket should not only calculate the proportion of effective contact stress, but also calculate the effective total leakage rate. (3) When the contact stress is large and the effective contact stress accounts for a high proportion, the waterproof ability is controlled by the contact stress; when the contact stress is small or the proportion of the effective contact stress is small, the waterproof ability is controlled by the leakage rate. (4) The research results can provide theoretical guidance for gasket design.
2022 Vol. 39 (10): 65-70 [Abstract] ( 3300 ) HTML (1 KB)  PDF  (592 KB)  ( 1903 )
       Main Line: Electrification Engineering
71 Research on the Influence of Steady Arm Fault on Vibration Response of OCS
TIAN Shengping
Research purposes:Steady arm is a key component of OCS. Once a fault occurs, it will directly affect the safety of pantograph catenary current collection. It's necessary to study the influence of steady arm failure on the vibration response of OCS in order to implement fault diagnosis of steady arm. Firstly, through mechanism analysis, two kinds of faults are obtained, namely, wire clamp falling off and shackle falling off. Secondly, based on the fault simulation model of catenary steady arm, a catenary full-parameter fault simulation system is built to obtain the catenary vibration response parameters when the catenary steady arm fails. Finally, by analyzing the acceleration statistical data in the vertical and horizontal directions of the positioning point when the steady arm fails, the vibration acceleration response time and vibration frequency are extracted to identify the fault characteristics.
Research conclusions:(1) Vibration mode of the failed steady arm changes obviously and the horizontal acceleration increases dramatically. (2) The main frequency of the acceleration amplitude at the fault point moves forward, the corresponding peak decreases, and the phase angle continues to decrease. (3) The acceleration in horizontal direction of the fault point changes sharply, and the vibration response of the catenary is obviously abnormal, which will directly affect the normal operation of the train. (4) In practical engineering, this method can position and diagnose the fault of steady arm in time for the stable and reliable pantograph catenary current collection.
2022 Vol. 39 (10): 71-76 [Abstract] ( 3957 ) HTML (1 KB)  PDF  (810 KB)  ( 1871 )
       Terminal,Station yard and Building
77 Design of Uplink System of Xiangyang North Railway Marshalling Station
LI Dajun
Research purposes:In view of the inconsistency of the main technical standards of the connecting line of Xiangyang North Marshalling Station and the lack of reserved uplink system conditions, this paper makes an in-depth study and discussion on the division of operation work, layout, corner traffic flow, line distribution and construction transition of the uplink and downlink system of the marshalling station, and puts forward new ideas.
Research conclusions:(1)The uplink and downlink system of Xiangyang North Station adopts non-balanced division of work, which can make full use of existing facilities and equipment and reduce the interference to operation.(2)The reverse arrival route is used to introduce the North-West corner traffic flow into the uplink departure yard for axle increase and decrease. The exchange yard is composed of three shunting and exchanging lines of the uplink and three shunting and exchanging lines of downlink system for corner traffic flow treatment, which can effectively shorten the operation travel of the train in the hub, reduce frequency of locomotive pick-up and delivery trains and the interference to other technical operations, and improve the operation efficiency and capacity of the station.(3)Reducing transition times of interlocking software in construction transition design can effectively shorten the construction cycle and eliminate potential safety hazards.(4)The research conclusion can be used for reference for the scheme of new or reconstructed marshalling station.
2022 Vol. 39 (10): 77-81 [Abstract] ( 3829 ) HTML (1 KB)  PDF  (900 KB)  ( 1967 )
82 Analysis of Basic Station Type Scheme of Intercity Railway Underground Stations
WU Peng
Research purposes:With the release of the outline of the advance plan for railways in the new era of strong transportation, the construction of intercity railways in our country has entered a period of rapid development. Among them, the projects led by local governments, because more consideration is given to the integration of projects and urban planning and development and the comprehensive development and utilization of land resources, the route laying method is also mostly changed from above ground to underground, and the demand for public transportation is more and more important. As it gets higher, the traditional intercity railway station type can no longer meet the needs of the new intercity railway. At present, there are few theoretical studies on the station type scheme of the intercity railway underground station in China. In order to better carry out the design of the intercity railway underground station in the new period, different station type schemes of the underground railway station are analyzed.
Research conclusions:(1) A systematic analysis of the platform layout is conducted, and the operation function, station scale and adaptation conditions of different platform layouts are proposed. (2) The basic station layout plan is proposed for general intermediate stations, rail transit intermediate stations, and turnaround stations, and the transportation organization, engineering investment and turn-back capability of different station layout schemes are also analyzed, so as to provide ideas for the comparison and selection of intercity railway underground station schemes. (3) The research results have a good guidance and reference for the station layout plan of the intercity railway underground station.
2022 Vol. 39 (10): 82-86 [Abstract] ( 4038 ) HTML (1 KB)  PDF  (570 KB)  ( 1949 )
87 Research on the Mechanical Properties of Medium Plate Large Opening of Assembled Integral Underground Station
LEI Chong, SUN Bo, XU Junlin, ZHANG Zhen
Research purposes:Assembled underground stations are in line with the national advocacy of vigorously developing green buildings, and have been gradually applied in recent years. Based on the assembled integral station structure system used in Nanmen station of Wuxi to Jiangyin intercity rail transit, this paper puts forward the design scheme of large opening edge structure, and analyzes the mechanical properties of the structure, to provide theoretical basis for the application of the large opening edge structure of the assembled integral station.
Research conclusions:(1)It is reasonable and feasible to adopt the superposed assembly large opening edge structure scheme, which has the advantages of high assembly rate, no bracket template, fast construction, no taking up building space, and large stiffness of the opening edge structure. (2)Whether in the construction stage or in the use stage, the bearing capacity and deformation meet the requirements, the structure is safe and reliable. (3)In the construction stage, the safety redundancy of MYZAL(Y) beam and MYZAL(X) beam is relatively low, so the size of the long side of the opening and the construction load need to be controlled. (4)In the permanent use stage, the stiffness of the opening edge structure is significantly greater than that of the cast-in-place component. (5)The research results can be applied in the assembled underground stations.
2022 Vol. 39 (10): 87-93 [Abstract] ( 3901 ) HTML (0 KB)  PDF  (898 KB)  ( 1909 )
       Engineering Materials
94 Research on the Measures for Reducing Shrinkage and Anti-cracking of Ballastless Track Bed Concrete in Plateau Area
HE Niangzhe, LI Yongliang, ZENG Xiaohui, HU Jianping, LIU Haichuan, HUANG Zhixian, LI Xiangtao, LI Baoyou, PAN Zili, TANG Zhuo, LONG Guangcheng
Research purposes:In order to explore the anti-cracking performance of ballastless track slab concrete with elastic bearing block in plateau environment, the effects of internal curing agent, polyethylene fiber and mineral admixtures on the anti-cracking performance of concrete in plateau environment were studied through drying shrinkage test and central restraint block simulation test, and their anti-cracking mechanism was analyzed from the perspective of deformation inhibition.
Research conclusions:(1) In plateau environment, cracks appear in concrete specimens with fly ash and concrete specimens with mineral powder in 3 hours and 5 days, respectively, and the crack width and length increase with age. (2) The concrete specimens mixed with internal curing agent and polyethylene fiber have no cracks in 28 days; the internal curing agent and polyethylene fiber can significantly improve the crack resistance of concrete in plateau environment. (3) The shrinkage deformation of concrete mixed with curing agent and polyethylene fiber is small at early age, even slightly expanded, and the later shrinkage is also small. (4) Combined with the test results of free shrinkage and restrained cracking, in order to prevent concrete cracking in plateau environment, it is suggested that the 7 days free shrinkage of concrete should ≤100 με and 28 days free shrinkage ≤ 400 με. (5) The research conclusion can provide reference for the study of shrinkage cracking of concrete in plateau environment.
2022 Vol. 39 (10): 94-99 [Abstract] ( 3980 ) HTML (0 KB)  PDF  (777 KB)  ( 1905 )
       Research on Technical Standards and Specifications
100 Adaptability Analysis of China's High Speed Railway Standards in Thailand
SUN Haifu
Research purposes:China and Thailand cooperation project adopts China's high speed railway technical standards. In order to ensure the smooth implementation of the project, China's high speed railway standards should be adjusted according to local laws, policies and natural conditions, so as to better combine with the actual situation and meet the requirements of railway construction and operation. This paper compares and analyzes the design, construction and procurement of China and Thailand railway, and summarizes the corresponding adaptive measures, which has a strong reference significance for guiding overseas railway design.
Research conclusions:(1)China's high speed railway technical standards should be adjusted according to the laws, regulations, policies and environmental conditions of the country where the project is located.(2)Attention should be paid to the influence of land privatization and environmental protection in the selection of route schemes.(3)The civil structure should be determined in combination with local construction methods, construction capacity and mechanical equipment.(4)Priority should be given to local supply of construction materials, and international procurement should be made when necessary.(5)In principle, the railway external interface project should be completed by the local relevant departments.(6)This paper has a strong guidance for overseas railway projects.
2022 Vol. 39 (10): 100-104 [Abstract] ( 4007 ) HTML (0 KB)  PDF  (411 KB)  ( 2010 )
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