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2022 Vol. 39, No. 11 Published: 2022-11-15

Urban Rail Construction Main Line: Engineering Geology and Subgrade Main Line: Railway and Rail Research on Technical Standards and Specifications Main Line: Bridge Engineering Main Line: Tunnel Engineering Main Line: Research on Railway Networks Risk Management and Research

Main Line: Research on Railway Networks

	1	Research on the Spatial Pattern Evolution of Urban Railway Passenger Transport Accessibility in China
		YAO Han, FU Qiang
		Research purposes: In order to comprehensively measure the evolution of the Chinese city accessibility supported by railway passenger transport network based on the characteristics of whole travel time of railway passengers, this paper proposes the concept of "Travel Cumulative Time (TCT)", and selects representative time nodes for accessibility analysis and evaluation. Research conclusions: (1) The "four vertical and four horizontal" high-speed rail network plays a huge role in improving the accessibility between cities, and the high access network showing the pattern of large loops and radial extensions has taken shape. (2) The gravity center of access network represents a clear southward trend. (3) Railway construction has provided significant support for the improvement of urban accessibility in the western region in recent years. (4) Due to the design speed, mixed passenger and freight traffic, the accessibility level between cities in some sections of Shanghai-Wuhan-Chengdu Corridor and Southeast Coastal Corridor is not high, which affects the convenience and timeliness of passenger travel in these areas. (5) The research results can provide reference for scientific evaluation of railway passenger transport accessibility
		2022 Vol. 39 (11): 1-5 [Abstract] ( 4020 ) HTML (1 KB) PDF (1590 KB) ( 2121 )

	6	Research on the Railway Freight Transportation Development Strategy Considering the Construction of the High-speed Railway along the Yangtze River
		MA Chunshan
		Research purposes: With the sectional implementation of the high-speed railway along the Yangtze River, after the problem of passenger transportation has been effectively solved, the necessity of giving full play to the freight function of the existing railway channel and improving the comprehensive transportation system is further highlighted. In the context of the "three-step" construction of the high-speed railway along the river, this paper calculates the generalized cost based on time value, transportation costs, transshipment times and other elements, predicts railway trend and transfer volumes, and studies the development strategy of railway freight along the Yangtze River in stages, to provide reference for production practice. Research conclusions: (1) At present, the freight channel along the Yangtze River has the problems of long detour distance and low service efficiency. (2) The Shanghai-Wuhan-Chengdu Railway should undertake more express trains mainly based on containers on the premise of satisfying passenger services. (3) Under the background of the staged construction of the high-speed railway along the river, the first stage focuses on solving the problems of insufficient freight facilities and poor intermodal connections in the section from Chongqing to Wuhan; The second stage further releases the capacity of the Chongqing-Wuhan section to undertake part of the dam-overturning volume of the Three Gorges; In the third stage, a fast transportation channel along the Yangtze River from Chongqing via Wuhan to Shanghai will be formed. (4) The research results can guide the scientific and rational planning and development of the railway freight passage along the river.
		2022 Vol. 39 (11): 6-11 [Abstract] ( 3410 ) HTML (1 KB) PDF (804 KB) ( 1986 )

Main Line: Engineering Geology and Subgrade

	12	Research on the Nonlinear Algorithm for Lateral Deformation of Foundation under Lightweight Soil Replacement Embankment
		ZHOU Zhong, LI Fan, LU Siping
		Research purposes: At present, the research on the lateral deformation of the foundation under the lightweight soil embankment still lacks the corresponding theoretical algorithm. Therefore, this paper considers the particularity of the load on the embankment replaced by lightweight soil, and derives the theoretical solution of the lateral displacement of the foundation; Based on the Walsh formula and the assumption of the spherical pores of the soil element, a correction model of the deformation modulus considering the nonlinearity of the soil is proposed, and the nonlinear algorithm for lateral deformation of foundation under lightweight soil replacement embankment is comprehensively constructed. The effectiveness of this algorithm is verified by engineering examples, and the parameter sensitivity analysis is carried out. Research conclusions: (1) Through comparison and verification, the calculated value of the theoretical algorithm in this paper is close to the actual measured value, and the overall error between the two is 15.3%, which is reasonable. (2) Under the load of lightweight soil replacement embankment, the lateral displacement at the toe of the slope is vertically distributed as a "bow" curve. (3) The closer the position to the outer side of the embankment, the greater the lateral displacement of the foundation; As the Poisson's ratio of the foundation increases, the overall lateral displacement of the foundation increases, and the position of the maximum lateral displacement gradually moves upward; The larger the soil deformation modulus, the smaller the lateral displacement value; The wider the lightweight soil embankment, the smaller the lateral displacement. (4) The research results can provide a theoretical reference for the stability analysis of foam lightweight soil subgrades.
		2022 Vol. 39 (11): 12-18 [Abstract] ( 3321 ) HTML (1 KB) PDF (1457 KB) ( 2011 )

	19	Experimental Research on the Layered Reinforcement of Sludge by Consolidation and Solidification Composite Technology
		LUO Jiacheng, SHAO Jicheng
		Research purposes: To save the construction cost, the layered reinforcement method is used to reinforce the soft sludge, and the consolidation and solidification composite technology is adopted to reinforce the sludge in the test site, so that the treated sludge can meet the bearing capacity requirements of the construction. For the shallow surface sludge, the solidification technology is used to greatly improve the strength of the shallow soil. For the deep sludge, the vacuum preloading technology is used to make the sludge consolidated by drainage, so as to improve the bearing capacity of the underlying stratum. Research conclusions: (1) Solidified agent can generate considerable solidified effect on shallow sludge. When the solidified agent content is 4~8%, the characteristic value of bearing capacity in shallow solidified soil is 164~200 kPa. (2) The characteristic value of bearing capacity of sludge is just 40 kPa as the sludge is reinforced by only vacuum preloading. The consolidation and solidification composite technology is used to strengthen the sludge by layered reinforcement. When the solidified agent content is 4%~8%, the characteristic value of bearing capacity of the two-layered foundation is 96~170 kPa, and the shallow overlying crust has a significant effect on the soil bearing capacity. (3) For the two-layered foundation, the overlying crust has a certain stress diffusion effect. When the solidified agent content is 4%, the stress diffusion angle of the shallow solidified soil is 18.32°, which can effectively reduce the additional stress of the soft underlying stratum. (4) Consolidation and solidification composite technology can be used for large-scale reinforcement of coastal soft soil and sludge backfill soil foundation.
		2022 Vol. 39 (11): 19-24 [Abstract] ( 3695 ) HTML (1 KB) PDF (1335 KB) ( 1899 )

Main Line: Railway and Rail

	25	The Influence of Line Key Points on Vertical Parameters Design of 400 km/h High-speed Railway
		HE Qing, XU Shuangting, GAO Tianci, HU Jianping, ZHU Ying, WANG Ping
		Research purposes: The planning and design of 400 km/h high-speed railway is an important goal for the construction and development of high-speed railway in China. Currently, there has been no study on the design standard of 400 km/h high-speed railway vertical parameters. Under the condition of driving safety and passenger comfort in high-speed train, this paper designs and verifies the vertical parameters of 400 km/h high-speed railway, so as to provide a theoretical basis for subsequent engineering application. Research conclusions: (1) Under the conditions of same algebraic difference between adjacent gradients and length of tangent between curves, the maximum train vertical vibration acceleration value decreases with the increase of the vertical curve radius. The minimum vertical curve radius of 400 km/h high-speed railway is recommended to be 30 000 m. (2) When the vertical curve radius is greater than or equal to 20 000 m, the maximum value of the vertical vibration acceleration of the train body is little affected by the algebraic difference between adjacent gradients. (3) The vertical vibration acceleration of the car body gradually dissipates as the length of tangent between curves increases, and the superimposed vibration decreases. It is recommended that the minimum length of 400 km/h high-speed railway is 200 m. (4) This research method can provide technical support for the vertical parameters design of 400 km/h high-speed railway.
		2022 Vol. 39 (11): 25-32 [Abstract] ( 3367 ) HTML (1 KB) PDF (1099 KB) ( 1902 )

	33	Research on the Present Situation and Improvement Method for Precise Adjustment of Railway Tracks
		WANG Xiaokai, CAI Degou, WANG Peng
		Research purposes: It's difficult to effectively improve the amplitude of medium and long waves and control multi-wave irregularities with the existing track precision measurement and fine adjustment methods. Based on the current situation of railway precise adjustment in China and the variation characteristics of track irregularities, by analyzing the principle and improvement method of orbit detection, this paper studied on an improved operation method of track detection and fine adjustment based on the vertical deviation, in order to achieve the purpose of comprehensively improving the smoothness of railway works track fine adjustment. Research conclusions: (1) The detection method based on the vertical deviation method can effectively reduce the amplitude of the long-wave irregularity in the track, and reasonably arrange the operation procedures, which can further improve short-wave amplitude and continuous track irregularities, and improve the track smoothness as a whole on the premise of orbit orientation/height optimization and improvement. (2) In the section of poor track condition and easing curve, the vertical deviation error measured by the inspecting instrument for railway track will be too large. (3) The customized adjustment of railway tracks based on the sensitive wavelength of the vehicle body can further improve the stability of the operation dynamic effect.
		2022 Vol. 39 (11): 33-37 [Abstract] ( 4181 ) HTML (1 KB) PDF (470 KB) ( 2339 )

	38	Numerical Simulation of Lateral Resistance Sharing Ratio of Different Parts of Meter Gauge Sleeper
		WEI Kai, CAI Yuanhui, XIE Meng , YOU Rui, WANG Ping
		Research purposes: In order to study the lateral resistance sharing of meter gauge concrete sleeper and steel sleeper, the discrete element method is used to establish the ballast bed models of meter gauge concrete sleeper and steel sleeper respectively. The correctness of the discrete element model is verified by the lateral resistance test of a single sleeper, and the lateral resistance sharing ratio of meter gauge concrete sleeper and steel sleeper is further studied. At the same time, the measurement circle is set up in different parts of the discrete element model to monitor the ballast porosity, and the change law of ballast compactness is explored in different parts during the lateral movement of the sleeper. Research conclusions: (1) The end and bottom of the meter gauge concrete sleepers provide about 79% of the lateral resistance of the track bed, while the resistance of the side track bed of the sleepers with large contact surface with the ballast particles accounts for less, so the sleeper ballasts can fully participate in the action by means of compaction and partial cementation. (2) About 60% of the lateral resistance of the track bed is provided by the end of the meter gauge steel sleeper, and about 30% of the lateral resistance of the track bed is provided by the bottom of the sleeper. (3)The lateral resistance of the meter gauge concrete sleeper track bed mainly comes from the friction between the sleeper and the bottom ballast particles and the pressure of the ballast shoulder. The lateral resistance of the meter gauge steel sleeper track bed mainly comes from the extrusion friction of the ballast in the sleeper cavity and the pressure of the ballast at the ballast shoulder. (4)The research conclusion can provide reference for the design and maintenance of meter gauge CWR.
		2022 Vol. 39 (11): 38-42 [Abstract] ( 3369 ) HTML (1 KB) PDF (931 KB) ( 1920 )

Main Line: Bridge Engineering

	43	Research on the Influence of Cracks at End of Railway Simple Supported Box Girder on Mechanical Performance
		LI Xuebin, MA Lin, WU Guoqi, YANG Xinyi, DONG Liang, CHEN Qiang, ZHANG Shan, ZHANG Bo
		Research purposes: During the lifting process of precast box girder, due to the unbalanced force of each lifting point, longitudinal cracks are prone to occur near the lifting hole at beam ends. In order to test static performance of the structure after cracked damage of beam ends, the bending rigidity, crack resistance and torsional rigidity of 32 m simple supported box girder were analyzed through bending and torsional static load tests. Research conclusions: (1) During the lifting process, the box girder was subjected to large impact, resulting in multiple longitudinal cracks at the beam end, but did not cause cracks in the mid - span section of the beam. (2) The actual bending and torsional rigidity of the damaged box girder at the beam end are greater than the design rigidity, and the crack resistance meets requirements in codes. (3) The main reason for the large bending rigidity of beam is that the actual elastic modulus of structure is larger than the design calculation value. (4) The single track load does not control the stress design of the double track box girder section. (5) The cracks near the lifting points do not affect the mechanical performance of the beam. (6) The cracks should be closed to ensure the durability and safety of the structure. (7) The research results can provide guidance for the construction and quality control of railway precast simple supported box girder.
		2022 Vol. 39 (11): 43-49 [Abstract] ( 3370 ) HTML (1 KB) PDF (936 KB) ( 1916 )

	50	Experimental Research on the Side Shear Strength of Novel Composite Pier with Socket Connections
		LIU Baodong, FENG Mingyang, ZHANG Linlin, SUN Haibo, DOU Kangjian
		Research purposes: In order to meet the demand of green construction and rapid construction of bridge substructure, this paper carried out vertical loading tests and finite element numerical simulations on 7 novel corrugated steel-rubberized concrete composite pier-foundation specimens with socket connections to explore how connection types, embedment depths, shear studs, and end-bearing concrete affect their connect strength. Also, we studied the failure mechanism and side shear capacity of the proposed pier-foundation connections. Research conclusions: (1) Socket connections have a 36% higher side shear capacity than integrated connections with the same embedding depths. Side shear capacity is increased by increasing embedding depths and adding end-bearing concrete. Similarly, shear studs in joint areas may strengthen circumferential shear zones even more. (2) When subjected to vertical loads, the "quasi-three-direction" compression state greatly improves the joint's side shear strength, which is achieved through the "strong physical interlock" of concrete and steel corrugates. (3) The coefficient K, named as the corrugation enhancement coefficient, is proposed to assess the contribution of "strong physical interlock" to side shear strength. K's value ranges from 0.12 to 0.18, and the waveform is the primary indicator that influences K. Based on the stress state of the joints, a formula for shear capacity is proposed, and the calculation results agree well with the experiment and simulation analysis. (4) A formula for the minimum thickness of end-bearing concrete is proposed, based on the plastic stress distribution method and taking lateral load into account, which can provide technical support for the design and application of corrugated steel composite pier with socket connections.
		2022 Vol. 39 (11): 50-56 [Abstract] ( 4233 ) HTML (1 KB) PDF (786 KB) ( 1994 )

	57	Rockmass Mechanical Tests and Its Engineering Application about Complicated Geological Conditions Gravity Anchorage Basement
		GUO Xifeng, YU Meiwan, WANG Xinze
		Research purposes: The mechanical parameters of the rock and soil mass of the gravity anchor foundation are an important basis for the analysis (or review) of stability against sliding. In this paper, seven geologically representative foundations were selected and in-situ mechanical tests were carried out on the bottom of the gravity anchor foundation at the Jinsha River Bridge in the Tiger Leaping Gorge of Shangrila-Lijiang Expressway, to obtain mechanical parameters such as bearing capacity and friction coefficient of the base. Research conclusions: (1) The characteristic value of bearing capacity of crushed stone soil is 119 kPa and the base friction coefficient is 0.44, the characteristic value of bearing capacity of the strongly weathered phyllite is 508 kPa and the base friction coefficient is 0.35, the base friction coefficient of the cleavage dense zone in the excavation area is 0.45, which does not meet the design requirements. (2) The characteristic value of bearing capacity of the cleavage dense zone on the right side of the anchorage foundation is 719 kPa and the friction coefficient of the base is 0.95, the characteristic value of bearing capacity of the cleavage dense zone in the excavation area of the left anchor rake angle of the anchorage foundation is 720 kPa, the characteristic value of moderate weathered sandy slate bearing capacity is 1.44 MPa and the base friction coefficient is 1.22, the characteristic value of medium weathered sandy slate with phyllite is 1.44 MPa and the base friction coefficient is 0.65, and the characteristic value of strong weathered sandy slate with phyllite 719 kPa, which all meet the design requirements. (3) For the foundations of the crushed soil with the stone mass and the strongly weathered sandy slate with phyllite that does not meet the design requirements, the measures such as excavation and replacement of concrete, consolidation grouting, are used for reinforcement, and then the anti-slip stability factors of gravity anchors are reviewed. (4) The research results can provide reference for the safe and stable operation of gravity anchorage under complex geological conditions.
		2022 Vol. 39 (11): 57-62 [Abstract] ( 4072 ) HTML (1 KB) PDF (1034 KB) ( 1985 )

Main Line: Tunnel Engineering

	63	Research on the Excavation Damage Characteristics in Tunnel Surrounding Rock Based on Damage Mechanics
		LI Ao, ZHANG Dingli, HUANG Jun, DONG Fei, SUN Zhenyu, HOU Yanjuan
		Research purposes: The excavation damage of surrounding rock will inevitably affect the mechanical properties and stability of surrounding rock. When it is not controlled properly, failure or collapse accident may occur. Therefore, we must master the characteristics and evolution mechanism of surrounding rock damage, so as to provide basis for surrounding rock damage control and support design. Based on microseismic monitoring results, the damage characteristics of surrounding rock caused by tunnel excavation is revealed. The expression of damage zone is deduced by using strain softening model and damage mechanics theory without considering structural stress, which is compared with the measured results. The influencing factors of damage characteristics are further analyzed. Research conclusions: (1) The theoretical prediction results are in good agreement with the measured data, and when the worse the surrounding rock is, the smaller the error is. (2) The radius of surrounding rock damage zone increases with the increase of brittleness coefficient λ/E, and decreases with the decrease of surrounding rock cohesion c and internal friction angle φ. The radius of high damage zone of surrounding rock increases with the increase of ultimate damage parameter D_cr with the growth rate faster. (3) The ultimate damage parameter D_cr and brittleness coefficient λ/E are not only related to the parameters of surrounding rock itself, but also related to the support means. (4) The research results can provide reference for the prediction and safety control of excavation damage of surrounding rock.
		2022 Vol. 39 (11): 63-69 [Abstract] ( 3339 ) HTML (1 KB) PDF (946 KB) ( 1987 )

	70	Research on the Calculation Method of Tunnel Fault Resistant Based on Energy Release
		YUAN Jinxiu, WANG Daoyuan, CUI Guangyao, TIAN Xiaolu, YANG Yanling, YANG Jie, ZHANG Haotian
		Research purposes: Aiming at the stability of tunnel structure in the process of fault dislocation in high intensity area, the design and calculation method of anti-dislocation is discussed from the perspective of energy release and dissipation. Firstly, the strain energy that can be released when the surrounding rock reaches stability is calculated according to the maximum dislocation momentum; Secondly, the absorbed strain energy of lining structure and surrounding rock is determined according to the load deflection curve of material and the unit strain energy within the plastic zone; Finally, the stability of "surrounding rock-tunnel" system is determined under the given safety condition. Research conclusions: (1) Based on the principle of energy release and dissipation, the calculation formula of the releasable strain energy during the dislocation of the tunnel with stick slip fault is deduced, and the calculation method of the anti-dislocation design of the tunnel lining structure based on the releasable strain energy is established, which can be used in the anti-dislocation design of the tunnel. (2) The results of the anti-dislocation design and calculation method of tunnel lining structure based on releasable strain energy are more than 17% higher than the standard safety, which is safer. (3) "SBFRC+staggered joint reduction+damping layer+expanded arch foot of initial support+thickening of secondary lining arch foot" can be used as the anti-dislocation implementation scheme of actual tunnel crossing fault section.
		2022 Vol. 39 (11): 70-74 [Abstract] ( 3353 ) HTML (1 KB) PDF (498 KB) ( 1916 )

	75	Analysis of Aerodynamic Drag Coefficient of the Train in Tunnel
		WANG Yingxue, ZHANG Ziwei, YUAN Junxiang
		Research purposes: With the increase of the train running speed, aerodynamic drag will become the main role resulting in energy consumption. While train running in tunnel, the energy consumption of aerodynamic drag will enhance remarkably. In this paper, using three-dimensional model, based on LES (large eddy simulation) turbulence model, the aerodynamic drag characteristic of CRH3 train model was analyzed. Research conclusions: (1) The aerodynamic drag coefficients of the train running in the open air were obtained. By comparing the results with Japanese test data, the applicability of the numeral calculating method was verified. (2) The aerodynamic drag coefficients of train running in tunnel with different blocking ratios were obtained. By regression analysis of the data, the aerodynamic drag coefficients relationship with blocking ratios of tunnels was obtained, which shows that the aerodynamic drag coefficients have exponential function relationship with blocking ratios of tunnels, and the prediction formula was put forward. (3) Using the formula put forward in this paper, the aerodynamic drag coefficients of dual-head train running in tunnel were anticipated and the evacuated tube parameters design on the basis of equal aerodynamic drag was analyzed, which verified its reliability and practicability. (4) The research result can provide guidance for relevant analysis and design on aerodynamic drag coefficient of the train in tunnel.
		2022 Vol. 39 (11): 75-80 [Abstract] ( 3365 ) HTML (1 KB) PDF (846 KB) ( 1924 )

	81	Influence of Construction Method on Interaction of Surrounding Rock Structure of Loess Tunnel
		FAN Chuntan, LIANG Qingguo, FANG Zhiqun, ZHANG Tangjie, CAO Xiaoping
		Research purposes: Because of the characteristics of loess itself, the phenomenon of large deformation of surrounding rock and complex stress of supporting structure often occurs in the construction of loess tunnel. Therefore, the partial excavation method is generally used in the construction of loess tunnels. In order to find out the influence of different partial excavation methods on the interaction of loess tunnel surrounding rock structure, a water-rich loess tunnel is taken as the engineering background. The finite element software Midas GTS is used to simulate the CRD method, CD method and three-stage seven-step excavation method respectively. The displacement, stress and elastic reaction coefficient k of surrounding rock of three construction methods are analyzed and compared, and the numerical calculation results are verified through measured data and existing theories. Research conclusions: (1) Different construction methods have certain influence on the displacement, stress and elastic reaction coefficient k of surrounding rock of water-rich loess tunnel. (2) The rationality of the numerical simulation results is verified by the measured data and the existing theory, Therefore, the value of elastic reaction coefficient k of surrounding rock in Table 2, it can provide reference for the design and construction of similar projects in the future. (3) The research results are helpful to understand the characteristics of the surrounding rock structural interaction of water-rich loess tunnel, and it can be applied to the related fields of calculation and analysis of water-rich loess tunnel.
		2022 Vol. 39 (11): 81-87 [Abstract] ( 3400 ) HTML (1 KB) PDF (814 KB) ( 1921 )

Urban Rail Construction

	88	Ground Settlement Analysis of a Double-line Shield in Hangzhou Gas-bearing Strata
		DING Zhi, XU Jiaoming, HE Chenyang, CHENG Kang, DIAO Hongguo
		Research purposes: Compared with non-gas-bearing strata, surface settlement patterns induced by double-line shield tunneling in gas-bearing strata have rarely been reported. In order to study the surface settlement pattern induced by double-line shield tunneling in gas-bearing strata, a systematic summary of the distribution and composition of shallow gas in domestic metro construction areas was first conducted, and continuous surface deformation monitoring was carried out for double-line shield construction in gas-bearing strata based on the Tangqing interval section of Hangzhou Metro Line 7 project to summarise the surface settlement pattern induced by double-line shield tunneling in gas-bearing strata. Research conclusions: (1) The surface settlement caused by shield tunneling in gas-bearing strata has a large impact range, and the surface settlement stabilizes after 25 days of shield passage. (2) There is a "three-time disturbance" effect when shield tunneling in gas-bearing strata. (3) The existence of an "intermediate pressure zone" in the gas-bearing soil leads to incomplete exhaust of the soil and the existence of matrix suction, which makes the settlement caused by shield tunneling in the first line larger than that in the second line. (4) The surface settlement and soil loss rate in the first line of shield tunneling in the gas-bearing strata are larger than that in the second line, which is different from the pattern in soft soil areas. (5) The research results have a reference role in setting reasonable shield construction parameters and controlling surface deformation in the gas-bearing soil areas.
		2022 Vol. 39 (11): 88-93 [Abstract] ( 4052 ) HTML (1 KB) PDF (562 KB) ( 1915 )

	94	Construction Influence of Pile Group Foundation with Different Number of Foundation Piles Undercrossed by Shield Tunnel
		TANG Jinsong, ZHANG Bao, ZHAO Shuyin, JIANG Jingshuang
		Research purposes: During the construction process of pile group foundations undercrossed by shield tunnel, what impact to pile group foundation with different area of foundation caps and different number of foundation piles is a concern problem to construction of metro tunnel. In order to explore the influence of shield tunnel underpass construction on pile foundations of different sizes of caps and different number of foundation piles, the low cap and friction pile group foundation was taken as the research object. The settlement and inclination law of cap were analyzed for different sizes of pile caps undercrossed by shield tunnel directly and laterally, as well as the horizontal displacement of the cap were analyzed when shield laterally passes under pile group foundation. Research conclusions: (1) When shield tunnel pass under pile group foundation with the same horizontal spacing, the settlement of center position of the top of cap increases with the increase of area of cap and the number of foundation piles, and there is little difference in the impact of inclination of cap. (2) When shield tunnel laterally underpasses pile group foundation, the horizontal displacement of cap increases with the increase of area of cap and the number of foundation piles. (3) When the horizontal spacing is less than 2 times of tunnel diameter, especially shield tunnel directly passes under pile group foundation, the size of cap and the number of foundation piles has a greater impact on the settlement of pile group foundation, and the pile group effect is more obvious. (4) The research results can provide reference for design and construction of pile group foundation undercrossed by shield tunnel.
		2022 Vol. 39 (11): 94-99 [Abstract] ( 4025 ) HTML (1 KB) PDF (480 KB) ( 1958 )

Research on Technical Standards and Specifications

	100	Trends and Suggestions to the Development of International Railway Standards
		JING Guoqing, ZHANG Hongping, WANG Haoyu, WANG Chuang
		Research purposes: Based on the research of organizations related to international railway standards such as the International Union of Railways, the International Organization for Standardization and the European Committee for Standardization in the past ten years, this paper surveys the formulation and development trends of relevant railway standards, including the process, framework of international standard organizations of railways and China's cooperation with them, provides countermeasures and suggestions for the future "going global" competition and cooperation of China's railway standards, and lays the foundation for high-level development of the Belt and Road Initiative. Research conclusions: (1) China should actively lead and participate in the formulation of relevant international standards and norms to increase its influence and voice. (2) It is necessary to develop the railway interconnection system for countries along the Belt and Road early to improve the adaptability and influence of domestic standards under international rules. (3) Enhance international communication and cognition through seminars, training courses, interviews, and other forms to provide strategic references, which will support China to play a leading role in the formulation of international standards in the future. (4) Scientific research institutions and enterprises should advance the development of the international railway standard training system, improve the comprehensive international professional qualities of Chinese enterprises, and enhance the training and reserve of relevant talents. (5) The research results have certain guiding significance for China's railway "go global" and the standardized construction of the railway projects along the "Belt and Road".
		2022 Vol. 39 (11): 100-105 [Abstract] ( 4416 ) HTML (1 KB) PDF (916 KB) ( 1958 )

Risk Management and Research

	106	Risk Assessment of Railway Tunnel Construction Based on Grey Fuzzy Linguistic Theory
		WANG Peng, WEI Qiang, WANG Jingchun, ZHAO Guotang
		Research purposes: In the construction of railway in complex and dangerous areas, tunnels account for a relatively high proportion, which is often ultra-long and deep buried, facing construction difficulty such as complex engineering geology, frequent and strong earthquakes, natural disasters and difficult construction conditions. Construction safety accidents such as landslides, water gushing and rock explosion are easy to occur. In order to prevent the tunnel construction accidents, the tunnel construction risk assessment model of the gray fuzzy linguistic theory is established, which provides a scientific and reasonable method for the risk control of the railway tunnel construction. Research conclusions: (1)For the risk factors in the process of railway tunnel construction, which have the characteristics of grey, fuzziness and randomness, the concept of interval grey fuzzy uncertain linguistic variables is given based on the theory of interval uncertain linguistic variables, and the railway tunnel construction risk assessment model of grey fuzzy linguistic theory is established. (2) From the 4 attributes of "safety, quality, construction period and environment", and 11 influencing factors such as natural weather and geological conditions, the risk analysis hierarchy is established. (3) A complex railway tunnel construction is taken as an example to verify the feasibility and effectiveness of the model. It is shown that geological conditions, natural weather, and other factors have great influence on railway tunnel construction. (4) The model can more comprehensively and truly use expert opinions to assess risk factors for the railway tunnel construction, and provide a scientific and reasonable basis for risk management and control of the complex railway tunnel construction.
		2022 Vol. 39 (11): 106-112 [Abstract] ( 4882 ) HTML (1 KB) PDF (507 KB) ( 1937 )