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2023 Vol. 40, No. 1
Published: 2023-01-15
Engineering Economy and Management
Terminal,Station yard and Building
Engineering Materials
Main Line:Railway and Rail
Main Line:Bridge Engineering
Main Line:Tunnel Engineering
Main Line:Engineering Survey and Design
 
       Main Line:Engineering Survey and Design
1 Discussion on the Interbedded Soil Seismic Liquefaction Discrimination in Railway Engineering
FAN Jin, ZHAO Ping
Research purposes: In Jiangsu and other coastal areas, interbedded strata with rhythmic deposition of cohesive soil, silt and silt sand are widely distributed. At present, there is still a lack of empirical data on the liquefaction of interbedded soil, and there are few targeted studies. The liquefaction properties of such stratum are still unclear. Therefore, it is necessary to discuss how to discriminate the seismic liquefaction of interbedded soil, so as to provide design basis for all kinds of railway engineering.
Research conclusions:(1) The Code for Seismic Design of Railway Engineering is not applicable to the liquefaction discrimination of interbedded soil; Interbedded soil detailed liquefaction discrimination cannot match the preliminary discrimination in the Code for Investigation of Geotechnical Engineering(Jiangsu); The reference value of interbedded soil liquefaction discrimination results of the Specification for Geotechnical Investigation in Soft Clay Area reduced. (2) The test methods for interbedded soil liquefaction discrimination in current codes and specifications have problems of mismatching the discrimination depth, reduction coefficient and liquefaction grade, which brings difficulties to practical application. (3) At present, there is a lack of empirical data on the liquefaction of interbedded soil, and the seismic damage data of such strata need to be further accumulated and studied. (4) At present, it is still unclear how to discriminate the liquefaction of interbedded soil. It is advisable to comprehensively judge the liquefaction of interbedded soil by using various methods on the basis of referring to the relevant codes and specifications of interbedded soil, which is beneficial to the engineering safety. (5) This research can provide a reference for the investigation and design of railway engineering in Jiangsu.
2023 Vol. 40 (1): 1-4 [Abstract] ( 2564 ) HTML (1 KB)  PDF  (623 KB)  ( 1312 )
5 Experimental Research on the Freezing Strength of Catenary Foundation in Electrification Reconstruction Project
HE Fei, WANG Xu
Research purposes: In order to ensure normal work and long-term stabilities of catenary foundations of the electrification reconstruction project of Golmud to Lhasa Section, it is necessary to focus on the freezing strength of the catenary foundation and frozen soil and its influencing factors. In this paper, direct shear tests of the contact surface between frozen silt and concrete under various temperatures and moisture contents were carried out by using a large stress controlled shear apparatus.
Research conclusions:(1) The shear stress-displacement curve of the contact surface is mainly divided into three stages: elastic deformation, plastic deformation and sliding failure. (2) The shear strengths of the contact surface are proportional to the normal stress, and inversely proportional to the freezing temperature. (3) When the moisture content of the sample is lower than the saturated moisture content, the shear strength of the contact surface increases with the increase of moisture content. When the moisture content of a sample exceeds the saturated moisture content, the shear strength of the contact surface decreases slightly with the increase of the moisture content. (4) With the decrease of temperature, the internal friction angle of the contact surface decreases, and the cohesion increases linearly. The effect of cohesion on the freezing strength of the contact surface is more prominent. The cohesion of the contact surface increases first and then decreases with the increase of water content, and the internal friction angle decreases with the increase of water content. (5) The research results can provide a reference for design of catenary foundation in permafrost regions.
2023 Vol. 40 (1): 5-12 [Abstract] ( 2567 ) HTML (1 KB)  PDF  (2633 KB)  ( 1147 )
       Main Line:Railway and Rail
13 Temperature Effect Analysis of CRTS Ⅱ Ballastless Track with Different Substructures
ZHOU Rui, YUAN Wenhao, ZHU Xingsheng, LIU Hanlin, YANG Huaizhi, WANG Yi
Research purposes: Bridges, roadbeds, and transition sections are the main substructure for the high-speed railway ballastless tracks. It is important to study the influence of different substructures on the temperature distribution in the CRTS Ⅱ slab ballastless track. Based on the field temperature monitoring data within half a year, the characteristics of the temperature and temperature gradient in the track slabs on three substructures (e.g. the simply supported box girder bridge, roadbed, the transition section between roadbed and bridge) are compared and analyzed in this paper.
Research conclusions:(1) The temperature in track slab on transition section has the most remarkable feature of non-Gaussian and non-stationary in half a year, while the roadbed has the worst non-Gaussian feature. Within the four special temperature days, the variation of internal temperature in the maximum temperature day is the largest. However, the variation of temperature gradient in maximum temperature difference day has the greatest amplitude. (2) As for various types of substructure, the temperature difference and temperature gradient of the track slab on transition section have the most notably variation, followed by those temperature variation of the roadbed and the transition section. (3) The relationship among the internal temperature in track slab on different substructures, the temperature in soil body of roadbed, and the ambient temperature presents obvious nonlinear relationship, in which the quadratic polynomial fitting function is used to reflect the nonlinear relationship between the temperature in the track slab and ambient temperature. In addition, the fitting R2 of the track temperature on the bridge is 0.803, which is higher than that on the transition section (0.752) and the roadbed (0.635). (4) This research could provide important temperature measuring data of the service performance evaluation for the ballastless tracks in high-speed railway.
2023 Vol. 40 (1): 13-20 [Abstract] ( 2544 ) HTML (1 KB)  PDF  (2242 KB)  ( 1159 )
21 Experimental Research on the Vibration Reduction Characteristics of the Vibration Reduction Turnout in Metro Depot
LIN Shan, CHEN Yanming, FENG Qingsong
Research purposes: Metro depot has the characteristics of many turnouts and track joints, small curve radius and low train speed, and the vibration reduction design of the track structure generally refers to the main line of the subway, and the actual vibration reduction effect is not clear. In order to understand the vibration reduction effect of double-layer nonlinear fastener in turnout in metro depot, the experimental research of vibration reduction turnout in metro depot was carried out.
Research conclusions:(1) The double-layer nonlinear fastener can reduce the vibration of the track bed and platform below the fastener layer, but the vibration of the rail above the fastener layer increases significantly. When the train speed is 20 km/h, the track bed and platform ground at the frog attenuate by 6.6 dB and 4.1 dB respectively, and the rail increases by 8.6 dB. (2) After using double-layer nonlinear fastener, the rail vibration increases in most frequency bands, especially in 10~20 Hz; the attenuation of track bed is obvious in 60~400 Hz; the attenuation of platform ground is mainly in 20~60 Hz, and there is a certain amplification in 5 Hz and 10 Hz. (3) The rail-bed transfer loss at the vibration reducing turnout is significantly greater than that of the ordinary turnout. When the vibration is transmitted from the rail to the track bed, the attenuation occurs in the range of 1 000 Hz, in which the attenuation is significant within 20 Hz, and the attenuation is more than 35 dB. (4) The research results in this paper can be applied to the field of vibration reduction design of railway engineering.
2023 Vol. 40 (1): 21-27 [Abstract] ( 2580 ) HTML (1 KB)  PDF  (945 KB)  ( 1168 )
       Main Line:Bridge Engineering
28 Vibration Characteristics Analysis of Box Girder Structure of Elevated Track during Train Rendezvous
LUO Kun, JIANG Xing, DONG Yuying
Research purposes: Aiming at the vibration problem of box girder structure in the elevated rail during train rendezvous, based on the vehicle-bridge coupling dynamics theory, a co-simulation model of vehicle-bridge coupling under various train rendezvous conditions is established, and the vibration transmission law of the box girder structure during train rendezvous is analyzed from the perspective of time domain and frequency domain, in order to provide a theoretical basis for the vibration and noise control of the elevated rail box girder structure.
Research conclusions:(1) In the double-line constant speed intersection, the displacement response of the span of the box girder structure is greater than that of the train double-line unequal speed intersection, in which the vibration displacement response during the constant speed intersection is about twice that of the one-way operation at the top and bottom plate of the box girder, and the vibration displacement response during the unequal speed intersection is about 1.66~1.72 times that of the one-way operation. (2) The local vibration frequency of the box girder in the double-line constant speed intersection is basically the same as that in one-way operation, but the acceleration response amplitude during the constant speed intersection is about twice that of the one-way operation. (3) When the train passes, the vibration displacement at the flange plate is the largest, followed by the web, and the floor plate is the smallest. (4) The research results can provide a theoretical basis for the vibration damping design of the elevated rail box girder structure.
2023 Vol. 40 (1): 28-33 [Abstract] ( 2567 ) HTML (0 KB)  PDF  (1090 KB)  ( 1194 )
34 Research on the Maximum Temperature Difference between Core and Surface of Concrete Hollow Column during Service Period
LU Wenliang, PENG Wenqiang, CHEN Liangjiang, GAO Ce, ZHOU Yongzheng
Research purposes: The maximum temperature difference between the core and surface of the concrete member is the key parameter to determine the maximum temperature gradient. The maximum temperature difference between the core and surface of the concrete member is affected by solar radiation and air temperature. Data such as solar radiation intensity are difficult to measure directly, but the ambient temperature near the member influenced by the solar radiation and air temperature can be directly measured. The temperature of each wall of concrete hollow column located in Beijing is monitored for a long time and the monitoring data are statistically analyzed. A prediction model for calculating the maximum temperature difference between the core and surface of the concrete hollow column based on the maximum ambient temperature, the amplitude of the ambient temperature change and the heating rate of the ambient temperature near the member is proposed, and the F test and T test are carried out for the accuracy of the prediction model.
Research conclusions:(1) The temperature of each measuring point of the concrete hollow column presents a 24-hour period of periodic change, and the temperature change of the measuring point near the outer surface is obviously affected by the ambient temperature that near the member. (2) Under different seasonal conditions, the maximum temperature difference between the core and surface and surface cracking risk of the south wall of the concrete hollow column is greater than that of the rest of walls, and the maximum temperature difference of the core and surface of the east, west and south walls fluctuates significantly, while the maximum temperature difference of the core and surface of the north wall fluctuates less. (3) In one day, the changes of the temperature difference between the core and surface of the south wall is similar to the changes of the ambient temperature near the member, and the peak times are similar, and the change rate of temperature difference between the core and surface of the south wall is similar to the temperature rises rate of the ambient temperature that neat the member. (4) In one day, the maximum temperature difference between the core and surface of concrete hollow column is highly correlated with the maximum ambient temperature, the amplitude of the ambient temperature change and the heating rate of the ambient temperature near the member. (5) The constructed prediction model can calculate the maximum temperature difference between the core and surface of concrete hollow column more accurately, which has a reference value for determining the temperature effect of the concrete hollow tower column.
2023 Vol. 40 (1): 34-41 [Abstract] ( 2581 ) HTML (0 KB)  PDF  (1718 KB)  ( 1151 )
42 Research on the Ten Key Points of Construction Quality of Concrete Cast-in-place Pile
CHANG Juyou, LIU Dewei, ZHONG Zaihang, CHANG Yaoxi, HAO Yushun, HOU Long, MA Hang
Research purposes: For the construction of concrete cast-in-place pile of railway bridge and culvert, because of the collapse of local critical soft soil layer and the inaccurate prediction of the factors affecting the construction quality, the construction quality of part of cast-in-place pile is not up to standard, and the waste of rework treatment is serious, effective preventive measures must be taken to ensure the construction quality of cast-in-place pile, and ten key points of effective methods are put forward and studied.
Research conclusions:(1) The ten key points include: the entry of raw materials should be regulated; the mixture ratio should be tested; concrete pouring is necessary to control the slump; the soft ground should be based on the control of pile expanding; the location of pipe should be based on the control of buried depth; the sediment thickness should be controlled at the bottom of the pile; the concrete continuity should be controlled in the pile; the compressive strength should be controlled at the top of the pile; the integrity test is based on optimal treatment; the whole process is based on the coordination. (2) The implementation of the ten key points makes the cast-in-place piles all up to the standard and avoids the rework waste. (3) The research results can provide reference for improving the construction quality of the cast-in-place concrete pile in the fields of railway and highway.
2023 Vol. 40 (1): 42-46 [Abstract] ( 2548 ) HTML (0 KB)  PDF  (761 KB)  ( 1172 )
47 Operation Performance Verification of Continuous Box Beam in High Speed Railway
WANG Wei, MENG Xin, WANG Yigan, ZHOU Zheng, WANG Dongmeng
Research purposes: The verification technology of operation performance of continuous box beam with common span is sorted out, in order to provide technical guidance for better operation performance verification of continuous box beam with common span of high-speed railway. Based on the data of the dynamic performance test of high-speed railway bridges in China in recent years and the relevant theoretical research, the measured samples of bridge dynamic performance are statistically analyzed, and the recommended ordinary values of the operation performance evaluation parameters of prestressed concrete continuous box beams at the operating speeds of 250 km/h and 350 km/h are given.
Research conclusions:(1) The tasks of operation performance verification of three types of continuous box beam with common span of high-speed railway are defined, and 10 main technical parameters for operation performance evaluation of continuous box beam are put forward. (2)The vertical natural frequency is determined by the power function of span, the vertical damping ratio is 0.5% to 2.0%, the ratio of deflection to span is 1/5 500 to 1/3 500 and 1/6 000 to 1/4 000 respectively, the vertical rotation angle at beam end is 0.60‰rad and 0.50‰rad respectively, the dynamic factor is 1.17 to 1.26 and 1.20 to 1.30 respectively, the vertical and lateral amplitude at midspan of beam is 0.25 to 0.80 mm and 0.10 to 0.15 mm respectively, the vertical vibration acceleration at midspan of beam is 0.25 to 0.40 m/s2, the lateral amplitude at pier top is chosen as the ratio of the height of pier and the lateral average width of the pier in the range of 0.5 to 4.2, the relative lateral displacement of rail support on both sides of adjacent beam end of ballastless track is 0.5 mm. (3) The research results are in line with the actual state of high-speed railway bridges, which can provide support for the revision of bridge operating performance verification specifications.
2023 Vol. 40 (1): 47-52 [Abstract] ( 2584 ) HTML (0 KB)  PDF  (756 KB)  ( 1151 )
       Main Line:Tunnel Engineering
53 Research on the Evolution Law of Tunnel Deformation Mode Based on Push Type Landslide
ZHAO Jin, WEN Lina, WU Honggang
Research purposes: With the rapid development of land transportation in China, the problem of tunnel diseases caused by landslides has become increasingly prominent in mountainous areas. The most fundamental cause of tunnel deformation and destruction is the change of tunnel stress mode caused by landslides. At the same time, the different deformation stages of the slope have great influence on the mechanical deformation mode of the tunnel structure, and there is a lack of in-depth research in this area at present.
Research conclusions:(1) Taking the tunnel-landslide parallel system as the research object, based on the deformation characteristics of the rock and soil mass of the sliding landslide, it is revealed that the essence of progressive failure process of tunnel is the process of landslide thrust and rock and soil resistance change. The movement characteristics of landslide in different evolution stages and the mechanical characteristics of tunnel are preliminarily discussed. Based on the stress mode of tunnel in different evolution stages, the models of semi-infinite long beam and semi-infinite long beam-cantilever beam are established. (2) Based on the theory of elastic foundation beam and structural mechanics, the deformation of tunnel structure in and out of the landslide is analyzed by coupling method. The theoretical calculation formulas of stress and deformation modes of tunnels in different stages are established, and the analytical expressions of corresponding control sections are put forward, which can realize the evaluation of stress and deformation of tunnels in different stages of landslide evolution. (3) A comparative analysis and verification are carried out through model tests. The results show that the theory can predict the development of the stress and deformation of the tunnel in landslide, and provide theoretical reference for the design and reinforcement of the tunnel in landslide area.
2023 Vol. 40 (1): 53-61 [Abstract] ( 2516 ) HTML (0 KB)  PDF  (1386 KB)  ( 1232 )
62 Research on the Calculation of Tunnel Surrounding Rock Load in Sandy Cobble Soil Based on Barn Effect
WANG Mingsheng, LU Junfu, LI Minhao, DENG Yonggang
Research purposes: The sandy cobble surrounding rock particle system has uneven gradation distribution and point-to-point contact between particles, which is easy to cause loose surrounding rock, instability collapse and other outstanding problems in tunnel construction process. According to the typical granular material characteristics of sandy cobble surrounding rock, based on the principle of granary effect, this paper uses the discrete element theory of granular material to explore the calculation method of surrounding rock load of sandy cobble tunnel. The meso-mechanical behavior of sandy cobble soil under different meso-structures is analyzed, and the influence of sandy cobble particle gradation on soil pressure is explored to reveal the influence law of tunnel span on tunnel surrounding rock load.
Research conclusions:(1) A modified Janssen formula for calculating vertical pressure of sandy cobble soil is proposed, and the steering ratio of important coefficient in the formula is determined. (2) The influence law of sandy cobble particle gradation on vertical pressure and lateral pressure of soil is revealed, and the calculation formulas of bottom pressure and lateral pressure of sandy cobble soil are obtained. (3) Through the simulation experiment of different span tunnel model, the vertical load correction coefficient is proposed. The load calculation value of sandy cobble surrounding rock by using the correction coefficient method is similar to the simulation calculation results, which verifies the accuracy of the formula calculation. (4) The load calculation method of sandy cobble surrounding rock based on Janssen model is established, which can provide theoretical basis for fine design of tunnel in sandy cobble stratum.
2023 Vol. 40 (1): 62-67 [Abstract] ( 2553 ) HTML (0 KB)  PDF  (1064 KB)  ( 1156 )
68 Research and Application of Top Pilot Tunnel Method Rescue Technology in TBM Jamming
ZHANG Minqing, XIN Weike, JIA Dapeng, SI Jingzhao, WANG Huanlong
Research purposes: TBM has been widely used in the field of underground engineering construction in China, but for complex geological conditions, the problem of TBM jamming is still very prominent. During construction, it has encountered difficulties in varying degrees such as continuous jamming, long-term jamming, water and mud inrush, equipment scrapping and construction method change, which not only delayed the construction period, but also greatly increased the project construction cost. Therefore, it is very necessary to study the prevention and control technology of TBM jamming under complex geological conditions and the safe and rapid escape technology after TBM jamming. Gaoligongshan Tunnel is 34 538 m in length. The inlet is constructed by drilling and blasting method, and the outlet is constructed by TBM method. During TBM construction, tunneling is relatively smooth under general geological conditions, but when the complex geological conditions such as the fault fracture zone, lithologic contact zone, joint dense belt, weathering alteration belt and soft rock extrusion zone are encountered, there are still 19 times jamming accident including 8 positive holes and 11 flat guide, seriously affecting the normal TBM tunneling, especially serious jamming, the conventional methods are difficult to be effective, so it is necessary to study safe and effective techniques to ensure the normal tunneling of TBM.
Research conclusions:(1) The top pilot tunnel method is an effective way to deal with TBM jamming. (2) When the top pilot tunnel method is used to deal with TBM jamming, the headroom width of the pilot tunnel should be 120 cm and the headroom height should be 130 cm. The pipe shed workshop should be set within 120° of the arch. The pipe shed should have a diameter of 76 mm, a circumferential spacing of 40 cm, an elevation of 1 ° ~ 3 °, and the length should pass through the fracture zone in front of the tunnel at one time. (3) The research results can be popularized and applied in TBM construction of similar tunnels.
2023 Vol. 40 (1): 68-75 [Abstract] ( 2606 ) HTML (0 KB)  PDF  (1660 KB)  ( 1906 )
76 Research on the Damage Characteristics and Countermeasures of Railway Tunnel in High-intensity Earthquake Area
WU Shiyan
Research purposes: To clarify the damage characteristics of tunnel after earthquake and then propose reasonable earthquake damage treatment techniques for high-intensity earthquake area, the relevant research is carried out based on the post-earthquake renovation project for Daliang tunnel in Second Lanzhou-Urumchi double-line. The site investigation is carried out to clarify the disaster characteristics of the Daliang tunnel after the earthquake. Meanwhile, according to geophysical prospecting, drilling and on-site data collection, and based on the comprehensive evaluation of seismic damage, targeted treatment technical measures for the tunnel seismic damage is proposed. Furthermore, in combination with field tests, the application effect of the technical measures proposed in this paper are verified to provide references for similar anti-seismic design for tunnels.
Research conclusions:(1) The surface cracks at the exit section of the tunnel after earthquake are distributed in a feather shape with the characteristics of tension or compression, and the cracks are obviously staggered. (2) The damage of tunnel structure is affected by the fault in a space dependent manner, with prominent characteristic effect. The structure of the entrance and exit sections are shifted to the upper right and the lower left respectively, and the structure dislocation and deformation damage in the core area of the fault are serious. (3) The ground cracks shall be treated by combining layered tamping with cement improved soil and grouting mortar. The comprehensive treatment schemes of "large rigidity circular lining + large reserved deformation+shock absorption and energy dissipation layer+segment design", "grid steel frame + C40 molding concrete" and "crack sealing + base grouting" are proposed for classⅤ,Ⅳ,Ⅲ and below damages, respectively. (4) The field monitoring results show that displacement of secondary lining in whole tunnel is stable, and primary support and secondary lining are mainly characterized by asymmetric stress, but the overall stress is small, which proves effectiveness and rationality of the proposed support scheme.
2023 Vol. 40 (1): 76-83 [Abstract] ( 2530 ) HTML (0 KB)  PDF  (1695 KB)  ( 1183 )
       Terminal,Station yard and Building
84 Planning and Design of Transport Hub of Sinking Railway Station - Taking Jiaxing Station as an Example
WU Meifa
Research purposes: Many railway passenger stations located in the central urban area need to be upgraded urgently. In order to overcome the contradiction between food and land, a new kind of railway passenger station - sinking railway station came into being. There is still a lack of relevant research on this aspect in China. This paper seeks to provide reference for the traffic planning and design of the sinking railway station in the future through the experience gained in the design of Jiaxing Station Hub.
Research conclusions:(1) The sinking of the station building can return the ground space in front of the station to the citizens, which is conducive to improving the overall image of the area, improving the transfer conditions, and realizing the separation of people and vehicles. (2) The drop-off area should be the next floor of the station, which is conducive to the layout of remote garage and commerce, and can drive the comprehensive development and utilization of underground space. (3) The entrance and exit of the hub shall be convenient for vehicles from all directions to enter and exit quickly and reduce the traffic pressure on the ground roads; the way of underground loop or underground ramp can be adopted to realize the separation of passing vehicles. (4) The traffic organization of "lower in and lower out" makes it difficult to separate the pedestrian flow lines in and out of the station, and the setting of signs and directions is complex. Different from the conventional way of drop-off and transfer, higher requirements are put forward for the later operation management. (5) This paper has reference significance for the determination of the railway station transformation scheme in the central urban area.
2023 Vol. 40 (1): 84-90 [Abstract] ( 2539 ) HTML (0 KB)  PDF  (2594 KB)  ( 1251 )
91 Research on the Bearing Capacity of Micro Steel Pipe Pile in Loess Area with Large Thickness
ZHANG Xiaobing, SHI Lei
Research purposes: Micro pile has been widely used in foundation reinforcement for its advantages of small diameter, high bearing capacity and simple technology. There are few researches on the bearing capacity of micro steel piles in loess area. Relying on a practical reinforcement and deviation correction project, the vertical bearing capacity test of single pile of micro steel pipe pile on site was carried out, by means of theoretical analysis and numerical simulation, some conclusions were confirmed, in order to study the failure mode and bearing performance of micro steel pipe pile in loess area with large thickness.
Research conclusions:(1) The bearing capacity of micro steel pipe pile determined by body material is the biggest, the bearing capacity determined by side resistance and end resistance is the least, and the bearing capacity determined by the stability is in the middle. (2) In normal working conditions, the actual bearing capacity of micro steel pipe pile is much higher than the theoretical calculation value, which is about 1.3 times more than the theoretical calculation value. (3) The micro steel pipe pile has good bearing performance and still works well when the slenderness ratio reaches 400. (4) In practice, the design of super-large slenderness ratio micro-piles is not economical and easy to buckling instability failure. (5) The research in this paper can provide reference for the research on the bearing performance of micro steel pipe piles in loess area.
2023 Vol. 40 (1): 91-96 [Abstract] ( 2463 ) HTML (0 KB)  PDF  (1290 KB)  ( 1157 )
       Engineering Materials
97 Stress Characteristics and Pressure Relief Effect Analysis of EPP Concrete in Soft Rock Tunnel
JILI Ciqie, LU Junfu, WANG Mingsheng, LIU Feng
Research purposes: During the operation of soft rock tunnel, the creep of surrounding rock leads to large deformation and cracking of tunnel lining, which seriously affects the operation safety. Based on the mechanical parameters of EPP (polypropylene) foam concrete obtained in the previous test, the stress characteristics and pressure relief effect of EPP foam concrete buffer layer in soft rock tunnel are analyzed, and a method to resist the creep of tunnel surrounding rock and reduce the deformation of lining is proposed, which provides a reference for similar tunnel engineering design.
Research conclusions:(1) EPP foam concrete, as a buffer layer of soft rock tunnel, has a good effect on improving the pressure of lining. (2) When the concrete with 64% EPP foam particles is used as the buffer layer and the thickness is 0.8 m, the compressive stress of the lining is the smallest, the lining is in the full section compression state, and the ultimate bearing capacity is the highest. (3) The yielding deformation of the buffer layer is the direct reason that determines its pressure relief effect. The higher the content and thickness of EPP foam in the buffer layer, the greater the yielding deformation, and the best pressure relief effect. (4) EPP foam concrete is applied to the buffer layer structure between the initial support and the secondary lining of soft rock tunnel in the direction of railway and highway engineering in the field of civil engineering. Its application prospect is broad. In order to further improve the pressure relief performance of EPP foam concrete and enhance the engineering practicability, it is necessary to carry out optimization research on the material mix ratio and compression characteristics.
2023 Vol. 40 (1): 97-102 [Abstract] ( 2525 ) HTML (0 KB)  PDF  (1537 KB)  ( 1124 )
103 Effect of Curing Methods on Hydration Processes and Mechanical Property of Track Slab Concrete
LI Shuming, XIE Yongjiang, ZHENG Xingguo, LIU Jing, WANG Yuehua, WENG Zhicai
Research purposes: Steam curing is a common curing method of track slab concrete, but high temperature steam curing is easy to cause internal damage of hydration products. In order to study the suitable accelerated curing method of track slab concrete, the effect of different curing methods on cement hydration and mechanical properties was explored. The temperature rise, strain, compressive strength and hydration process of track slab concrete were measured and the micro morphology of hydration product was observed under four curing methods, such as 45 ℃ steam curing, 45 ℃ dry heat curing, heat preservation curing and nature curing.
Research conclusions:(1) The temperature rise rate was quicker under steam curing and dry heat curing, the early compressive strength was improved significantly, thermal expansion deformation was exhibited at 0~7 h and shrinkage deformation was discovered after 7 h. Meanwhile, there were more hydration products at early stage, such as Ca(OH)2 and AFt, and more micro cracks at later stage, which made the later strength reduced. (2) The temperature rise rate of concrete under heat preservation curing were lower than the concrete under steam curing and dry heat curing, which could promote the early compressive strength of concrete. The demoulding strength of track slab concrete can meet requirement after curing 18 h. The concrete mainly showed shrinkage deformation under heat preservation curing, fewer defects of hydration products and stable strength in the later stage. (3) The heat preservation curing can be used as an accelerated curing method for track slab concrete.
2023 Vol. 40 (1): 103-108 [Abstract] ( 2502 ) HTML (0 KB)  PDF  (1115 KB)  ( 1123 )
       Engineering Economy and Management
109 Research on the Intelligent Control Method of Subway Shield Construction Schedule and Investment
DUAN Xiaochen, ZHAO Chenguang, LI Ming, SHI Zhendong
Research purposes: Shield construction is an important method in urban subway construction. Its construction schedule and investment control has very significant complex system characteristics, and is affected by the shield's own factors, construction conditions, construction organization and management, project content, technical standards, financing characteristics and other complex and changeable influencing factors, so there are many problems in the actual control process. In order to optimize the schedule and investment control system, this paper intends to conduct analysis modeling and demonstration.
Research conclusions:(1) Through the processing and analysis of the historical data of the completed project, the construction progress and investment information database of the subway section is established. (2) Nonlinear intelligent methods such as PSO cluster analysis and BPNN can be used to effectively estimate the construction schedule and investment objectives of the shield. (3) The dynamic optimization control management of shield construction schedule and investment can be realized by establishing the model based on PDCA, early warning and other management methods. (4) The dynamic optimization control model is applied in the shield construction of the actual subway section to realize the intelligent and information management of the subway section. (5) The research results can provide a feasible plan for the schedule and investment control of shield construction in the subway section.
2023 Vol. 40 (1): 109-115 [Abstract] ( 2556 ) HTML (0 KB)  PDF  (1145 KB)  ( 1179 )
116 Research on the Construction Period Buffer Management of Railway Engineering Technical Interface Process
BAO Xueying, ZUO Xin, HU Suoting, BAN Xinlin, XU Jianchao
Research purposes: In order to reduce the construction period delay caused by rework of technical interface process in railway project schedule management, a buffer management method of key technical interface process considering different overlapping relationships is proposed.
Research conclusions:(1) Based on the concept of technical interface exchange and PDCA cycle theory, a full life cycle model of railway engineering technical interface exchange is built. Through analyzing the interface information exchange process under different overlapping relationships, it is found that information transmission is the fundamental reason for affecting the construction period. (2) The DSM matrix is used to quantify the rework risk and probability caused by technical interface information interaction, determine the rework time and resource tightness, and take Bayu Tunnel of Lhasa-Linzhi Railway and Bayu Yarlung Zangbo River Third Line Bridge as examples to calculate the buffer size and duration of technical interface. (3) The results show that the buffer of construction period is 18.56 days, and the total construction period is 112.63 days. Compared with the method that does not consider the different overlapping relationships of interfaces, the total interface duration is reduced by 5.23%, that is, this method can effectively shorten the duration and promote the on-time completion rate of the project. (4) This method can provide a reference for the optimization and control of the progress of railway engineering technical interface.
2023 Vol. 40 (1): 116-121 [Abstract] ( 2549 ) HTML (0 KB)  PDF  (1085 KB)  ( 1179 )
122 Coordinated Governance Logic of High-speed Rail Station Area Land Development
MA Chunshan
Research purposes: The development of high-speed rail has strongly promoted the economic and social development in China, but there are problems with large investment, long cycles, and low yields. How to effectively develop the land around the high-speed rail station area, and then obtain income to nurture the construction of high-speed rail, so as to achieve sustainable development is an important research topic. This paper systematically analyzes the influence path of high-speed rail stations on the value of land and the interests of the participating entities during the development process, and explores the construction model of the cooperation mechanism in order to provide a reference for the land development at the high-speed rail station area in China.
Research conclusions:(1) The influence path of high-speed rail station area on the value of land is the maximum realization of node, place, and media. (2) The function matching of traffic and land development and the interest balance of multi-agent are the key factors affecting the land development in the high-speed rail station area. (3) The land development in the high-speed rail station area is the process of continuous cooperation between different participants to achieve their own interests and demands, which requires the joint support of internal mechanism and external environment to promote smooth implementation.
2023 Vol. 40 (1): 122-126 [Abstract] ( 2572 ) HTML (0 KB)  PDF  (1049 KB)  ( 1238 )
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