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2022 Vol. 39, No. 3 Published: 2022-03-15

Main Line: Railway and Rail Main Line: Communication Signals Main Line: Bridge Engineering Main Line: Tunnel Engineering Urban Railway Development and Technology Research Main Line: Engineering Survey and Design

Main Line: Engineering Survey and Design

	1	Deformation and Force Analysis of a Pit-in-pit Support Structure with Upper Support and Lower Anchor
		ZHAO Ping, NING Xiaoqing, WANG Jianwang, YAN Zihai
		Research purposes: In order to study the deformation and force characteristics of the support structure of the upper braced and lower anchored pit-in-pit, the excavation process of the pit-in-pit at Yiwu International Trade City Station was numerically simulated by means of a finite element model, while the later field measurement data verified the results of the preliminary analysis. Research conclusions: (1) During the excavation of the pit-in-pit with upper support and lower anchor, the horizontal displacement of the soil on the outer side of the enclosure pile finally shows a combination of "cantilevered" and "bulging" changes. The influence of excavation in the pit on the outer pit retaining pile the outer soil deformation is small, but the influence on the deformation of the soil on both sides of the inner pit is large; the overall change of the settlement value of the soil on both sides of the pit conforms to the change form of "parabolic type"; the deformation of the base elevation is centred on the middle point of the outer pit and spreads around, and the amount of base elevation becomes smaller and smaller, and the excavation of the inner pit does not affect the development pattern of the amount of base elevation. (2) During the excavation of the pit, the overall change of the internal force of the two concrete supports is similar, the first concrete support is under the greatest force, and the maximum anchor cable tension occurs at the second anchor cable, the excavation of the inner pit will reduce the internal force of the four supports of the outer pit to a certain extent. (3) The research results can provide reference for the design of the support structure and construction plan of similar pits.
		2022 Vol. 39 (3): 1-6 [Abstract] ( 3984 ) HTML (1 KB) PDF (2562 KB) ( 1943 )

	7	Local Stability Analysis of Diaphragm Wall Trench Wall Crossing Weak Interlayer
		AN Chenliang, WU Wenliang, ZHAO Xiaopeng, LIU Binghua, YAN Xinyong, WANG Daoyuan
		Research purposes: The instability of trench wall of diaphragm wall can be divided into overall instability and local instability. The construction of diaphragm wall through the weak interlayer is easy to induce the local instability. In order to study the local instability mechanism of trench wall during trench construction of diaphragm wall crossing weak interlayer, the disturbance range of trench construction is determined by using the trace of minimum principal stress of trench wall, the calculation model of local instability of trench wall is constructed, and the expression of local stability safety coefficient of trench wall is deduced based on plastic limit failure theory. Research conclusions: (1)The theoretical solution of the local safety factor of diaphragm wall obtained in this paper is consistent with the field ultrasonic detection results, which can be used to quantitatively analyze the local stability of the trench wall of diaphragm wall; (2) The length of soil arch can be approximately taken as the length of trench section, and the height of soil arch is positively correlated with the length of trench section and the internal friction angle of soil; (3) The local stability of the trench wall is directly proportional to the thickness, cohesion, and internal friction angle of the weak interlayer, and inversely proportional to the length of the trench, surface load and underground water level; (4) The research results have important guiding significance for the design and construction of diaphragm wall across weak interlayer.
		2022 Vol. 39 (3): 7-12 [Abstract] ( 2991 ) HTML (1 KB) PDF (1014 KB) ( 1976 )

	13	Research on the Capillary Rising Characteristics and Influencing Factors of Salt-containing Quartz Sand
		SHEN Yupeng, CAO Quan, CHEN Zhihang, ZHANG Xinpu, CHENG Yumeng
		Research purposes: Groundwater continuously invades the roadbed under the capillary action, which will lead to frost heave, salt heave and other diseases of the roadbed in severe cases, and the capillary rise height will be affected by soil density, initial moisture content, salt type and salt content. By mixing pure quartz sand with different types and contents of salt, the capillary water rise height test is carried out in this research. The capillary test results under different particle size gradations and initial moisture content are compared and analyzed, and the prediction equation of rising height is fitted. Research conclusions: (1) The stable height of capillary rise increases with the decrease of particle size. Under the condition of good gradation, the change of fine particle size content has a significant effect on the rate of capillary rise. (2) Within 4 000 min, the capillary rising speed will increase when NaCl and Na₂SO₄ are added into quartz sand. (3) The addition of two salts will reduce the final capillary rise height, but NaCl has little effect. (4) The research result can provide support for controlling capillary rise and dealing with salt heave, frost heave and other diseases.
		2022 Vol. 39 (3): 13-18 [Abstract] ( 2533 ) HTML (1 KB) PDF (642 KB) ( 1950 )

	19	Evolution of Particle Breakage of Soil-rock Mixture under Shearing
		TU Yiliang, LI Jun, CHAI Hejun, LIU Xinrong
		Research purposes: Under certain stress conditions, the particles of soil-rock mixture in subgrade fillings of railway, airport, highway will be broken, which leads to the deformation and stability problems of the filling engineering. Most of the existing researches focus on the characteristics of particle breakage after shear failure, but few on the dynamic evolution of particle breakage during the shearing process. Therefore, a large-scale direct shear test machine combined with acoustic emission acquisition system was used to conduct shear tests on soil-rock mixtures with six rock contents and three rock strength under six normal pressures in this paper. Research conclusions: (1)The relationship between cumulative AE counts and relative breakage index of the failure soil-rock mixture is linear, which proves that it is feasible to use acoustic emission technology in the study of particle breakage evolution of soil-rock mixture. (2)The particle breakage stage during the shearing process can be divided into five typical stages: no breakage stage, initial breakage stage, growth breakage stage, stable breakage stage and residual breakage stage. The corresponding response of stress and strain enters the elastic stage, elastoplastic transition stage, elastic-plastic stage, peak strength stage and plastic failure stage. (3)When the normal pressure is greater, or the rock content is greater, or the rock strength is lower, the duration of the no breakage stage and the residual breakage stage become shorter, and the duration of the initial breakage stage, growth breakage stage, and stable breakage stage get longer. (4)The difference of acoustic emission characteristics between soil-rock mixture and rock mass during shearing process is significant, which is due to the different continuity of material composition. (5)The research results can provide a new idea for the study of particle breakage of soil-rock mixture.
		2022 Vol. 39 (3): 19-25 [Abstract] ( 2429 ) HTML (1 KB) PDF (1094 KB) ( 1959 )

	26	Effect of Intersection Angle on the Critical Depth of High-speed Railway Embankment Obliquely Crossing Qanat Culvert
		LIU Xianfeng, ZHANG Yanfei, YUAN Shengyang, CHEN Zhiming, CHEN Weizhi
		Research purposes: During the construction of the subgrade engineering, the disturbance of the underground qanat culvert by the inclined crossing can cause different damage patterns in the culvert. Therefore, it is necessary to clarify the response of existing qanat culverts under the new high-speed subgrade engineering, to carry out the study of the subgrade engineering load-foundation soil-qanat culvert interaction through three-dimensional numerical simulation, and to determine the stability critical depth corresponding to different intersection angles. Research conclusions: (1) Due to the oblique intersection between the railway and the existing qanat culvert, when the existing qanat culvert crosses over the overlying subgrade, the subgrade surface will experience uneven settlement. (2) The larger the intersection angle between the culvert and the railway, the smaller the range of plastic zone, the smaller the shear strain around the culvert. The criteria for evaluating the critical depth of the qanat culvert can be better used to evaluate the intersection angle to the stability of the high-speed railway embankment oblique crossing qanat. (3) Combining the critical depth evaluation criteria, the stable critical depth change rule of the qanat culvert without support is obtained, that is, when the intersection angle is 0°, 30°, 60° and 90°, the critical depth of the qanat culvert is 14 m, 13 m, 8 m and 7 m. (4) The research results can provide a technical reference for the design of high-speed railways in the qanat region.
		2022 Vol. 39 (3): 26-31 [Abstract] ( 3866 ) HTML (1 KB) PDF (830 KB) ( 1911 )

Main Line: Railway and Rail

	32	Construction and Analysis of Track Irregularity Spectrum of Heavy Haul Railway
		GAO Jianmin, LAI Sicheng
		Research purposes: In order to master the characteristics of track irregularity of heavy haul railways, data preprocessing and digital characteristics analysis were carried out based on measured data of track irregularity on heavy haul railways. The different types of irregularity spectrum of heavy haul railways were estimated by Welch method. A uniform fitting model was proposed to characterize the spectrum characteristics of track irregularity, Levenberg-Marquart algorithm was used to fit track vertical profile, alignment, cross-level and gauge irregularity spectrums of heavy haul railway, and the average spectral fitting parameters were obtained. The fitting spectrums of track irregularities of heavy haul railway were compared with those of existing track irregularity spectrum. Research conclusions: (1) The track irregularity data of heavy haul railway has a stationary characteristic and basically obeys normal distribution. (2) The track geometry state of heavy haul railways analyzed is generally good, and the periodic wavelength components of different track irregularity spectrum are different, but all contain periodic wavelength components of 1.90 m and 1.15 m. (3) The track vertical profile, alignment and cross-level irregularity spectrums fitted are roughly the same as German low interference spectrum, while the gauge irregularity spectrum is generally worse than German high interference spectrum. (4) The research results can provide theoretical reference for the wheel-rail dynamic simulation analysis and maintenance management of heavy haul railways in China.
		2022 Vol. 39 (3): 32-39 [Abstract] ( 2401 ) HTML (1 KB) PDF (1607 KB) ( 1920 )

	40	Dynamic Analysis of Vibration-reduction Pad Floating Slab Track Transition Section on Urban Express Line
		FENG Qingsong, SUN Kui
		Research purposes: In order to study the reasonable setting of the transition section of vibration-reduction pad floating slab track on urban express line, the vertical coupling dynamic calculation model of vehicle track transition section ballastless track is established according to the principle of vehicle-track coupling dynamics. The dynamic response of wheel-rail system caused by CRH6 train passing through the transition section between double-block ballastless track and rubber vibration-reduction pad floating slab track at a speed of 160 km/h is calculated. The rail deflection change rate is selected as an evaluation index to measure the rationality of the transition section setting. The influence of different damping pad stiffness, transition stage number and adjacent transition stiffness ratio on rail deflection change rate is analyzed in detail. Research conclusions: (1)The stiffness difference at the joint between the double-block ballastless track and the rubber vibration-reduction pad floating slab track has a significant influence on the rail displacement and rail deflection change rate under the wheelset, but has a relatively little influence on the vertical acceleration of the train body and the wheel-rail force; (2)When the stiffness of rubber vibration-reduction pad is less than or equal to 50 MPa / m, the rail deflection change rate exceeds the limit value of 0.30 mm/m, so it is necessary to set a certain length of stiffness transition section at the joint of two kinds of tracks; (3)When the stiffness of the vibration-reduction pad in the standard vibration-reduction section is 25 MPa/m, it is suggested to set up three-level stiffness transition sections, each of which is a single slab track long, with a total length of 19.5 m, and the stiffness ratio of adjacent transition sections should be in the range of 1.4~1.6; (4)The research conclusion can provide some theoretical guidance for the design of the transition section of the rubber vibration-reduction pad floating slab track of the urban express line.
		2022 Vol. 39 (3): 40-45 [Abstract] ( 3939 ) HTML (1 KB) PDF (831 KB) ( 1875 )

	46	Peak Alignment of Track Dynamic Detection Data Based on Information Technology
		GUO Yeli
		Research purposes: The comparison of the data of track inspection car can analyze the maintenance quality and change trend of track. However, in practical application, there are different degrees of mileage error in each data, and waveform of these detection data cannot be aligned. This paper proposes a peak alignment technology, which calculates and corrects the mileage error of two or more detection data by selecting characteristic index, filtering the peak and trough point sets, eliminating the interference data and aligning calculation. This method is developed into software and integrated with the TQI analysis, data analysis, which can realize multi-dimensional application of detection data. Research conclusions: (1) Test results show that peak alignment can improve the fitting degree of two or more detection curves. This method can effectively improve the correction accuracy of relative mileage error. (2) This technology has been developed into software and applied to subway lines. After application verification, the expected effect has been achieved.
		2022 Vol. 39 (3): 46-49 [Abstract] ( 2191 ) HTML (1 KB) PDF (1259 KB) ( 1860 )

Main Line: Bridge Engineering

	50	Research on the Design Parameters of Long-span Railway Concrete Extradosed Bridge
		SUN Zonglei, ZHOU Yuewu
		Research purposes: With the rapid development of my country′s railways, especially high-speed railways, long-span railway concrete extradosed bridges have become more widely used. For example, the Yingshang Bridge on Shangqiu-Hefei-Hangzhou Railway with a main span of 220 meters, the Apengjiang Bridge on Qianjiang-Zhangjiajie-Changde Railway with a main span of 240 meters, and the Wulongjiang River Bridge on Fuzhou-Pingtan Railway with a main span of 288 meters. Through the research on the design parameters of long-span extradosed bridges at home and abroad, and combined with the impact of key design parameters on mechanical properties, the reasonable values of key design parameters are proposed. Research conclusions: (1) Appropriate structural systems for long-span railway concrete extradosed bridge should be selected according to local conditions to reduce structural deformation, maintenance and repair, and improve driving comfort; (2) The height-to-span ratio of pylon above the bridge deck and main girder for railway extradosed bridge should be 1/8～1/10; (3) The fulcrum depth-to-span ratio of main girder for the railway extradosed bridge should be 1/18～1/20, and the ratio of the mid-span beam height to the fulcrum beam height should be 0.45～0.6; (4)The stay cable safety factor of the railway extradosed bridge is recommended to be no less than 2.0; (5)The research conclusions can provide references for the design of railway bridges.
		2022 Vol. 39 (3): 50-54 [Abstract] ( 3330 ) HTML (1 KB) PDF (915 KB) ( 1914 )

	55	Analysis of Arch-beam Vertical Stiffness Ratio of the Continuous Beam-arch Composite Bridge on a High Speed Railway
		MA Kunquan
		Research purposes: In the design of beam-arch combination system bridges, the arch-beam stiffness ratio has a greater influence on the force and deformation, dynamic characteristics, structural stability, and construction methods of the overall structure. The arch-beam vertical stiffness ratio should be selected reasonably according to the specific situation to achieve the optimal structural system. In the existing beam-arch structure performance research, the arch-beam stiffness ratio is generally considered to be the ratio of the flexural stiffness of the arch rib and the main beam, and the stiffness of the structure can not be accurately reflected by the calculation method. In order to truly reflect the relative stiffness of the arch and girder of the beam-arch combination bridge, it is necessary to scientifically calculate the arch-beam vertical stiffness ratio according to the mechanical principles, and discuss its influence on the structural performance and related design parameters. Research conclusions: (1) The stiffness characteristics of the arch-beam composite structure can be fully reflected when the arch-beam vertical stiffness ratio is calculated by the ratio of the vertical stiffness of the arch rib to the main girder in the mid-span. (2) Accompanying with the increase of the arch-beam vertical stiffness ratio, the static live load deflection of side span is gradually increased. The deflection-span ratio of the side span will be greater than that of the main span, and the vertical stiffness of the structure may be controlled by the side span stiffness of the main beam when the arch-beam stiffness ratio achieving a specific value. (3) The load sharing by the arch ribs gradually increases under the effects of the self-weight of accessory equipment and live load with the increase of the arch-beam stiffness ratio, and the speed changes obviously from fast to slow. The increase speed of load-sharing ratio of the arch ribs will be basically stable when the arch-beam vertical stiffness ratio is greater than 0.621 2. (4) The continuous beam-arch combination system bridge can be divided into three types according to the vertical stiffness ratio of the arch ribs and the main beam. It is a strong beam and weak arch bridge when the vertical stiffness ratio of the arch beam is less than 0.3; it is a strong beam and strong arch bridge when the stiffness ratio of the arch beam is between 0.3 and 1.5; it is a strong arch and weak beam bridge when the arch-beam stiffness ratio is greater than 1.5. (5) The span ratio between the side and the middle span should be reduced simultaneously accompanying with the increase of the arch-beam stiffness ratio in the design of beam-arch combination system bridges. The relationship between the upper limit(y)of the reasonable side-mid span ratio and the vertical stiffness ratio(x)of the arch-beam can be taken as y=0.414 4x^-0.105.(6) The research results can be used as a reference for the structural analysis and engineering design of beam-arch combination system bridges.
		2022 Vol. 39 (3): 55-61 [Abstract] ( 2258 ) HTML (1 KB) PDF (588 KB) ( 1933 )

	62	Experimental Research on the Anti-collision Performance of Fabricated Bridge Deck System for Railway Box Girder
		LI Wangwang, YIN Jing, SU Yonghua, BAN Xinlin, WANG Wei, CHEN Shengli
		Research purposes: In order to promote the application of prefabricated structure in railway bridges, this paper conducts experimental research on the prefabricated bridge deck system of passenger-freight railway box girder under train derailment load. In order to investigate the anti-collision performance of the new type of prefabricated bridge deck system, the full-scale test models of prefabricated bridge deck system and cast-in-place ballast wall were designed and fabricated, the static load test was carried out on the full-scale model, and the anti-collision performance of prefabricated bridge deck system of passenger-freight railway box girder was compared and studied. Research conclusions: (1) The ballast wall of prefabricated bridge deck system is basically in elastic state under the action of multiple cycles of derailment design load, which meets the design requirements. (2) Under the ultimate state, the main diagonal cracks appear in the ballast wall and damage. The ultimate bearing capacity reaches 1.44 times of the derailment design load, and has a certain safety margin. Compared with the cast-in-situ ballast wall, it has higher bearing capacity. (3) The bolt connection between the prefabricated bridge deck system and the bridge deck flange plate is safe and reliable under the ultimate state of train derailment load, which meets the requirements of anti-collision design. (4) Under the derailment design load, part of the mortar layer on the line side is deactivated, and the structural cracks are mainly concentrated in the bottom of the line side floor and the ballast wall of the line side, and the cracks on the ballast wall are distributed horizontally. (5) The test phenomena and results verify the correctness of the design method and assumptions, and draw the conclusion that the shear ultimate bearing capacity of the retaining wall should be checked. (6) The research results can provide reference for anti-collision design and structural optimization of prefabricated bridge deck system of box girder in high-speed railway and passenger-freight railway.
		2022 Vol. 39 (3): 62-68 [Abstract] ( 2267 ) HTML (1 KB) PDF (939 KB) ( 1948 )

	69	Extreme Value Estimation of Vehicle-induced Load Effect of Bridge Based on Generalized Pareto Distribution
		CHEN Shuisheng, ZHAO Hui, LI Jinhua, TU Yong, WANG Yihao
		Research purposes: In order to accurately estimate the extreme value of vehicle-induced load effect of bridge and solve the problem of difficult threshold selection of GPD model, based on the extreme value prediction theory of generalized Pareto distribution, the method of K-S test automatic selection threshold and the method of extreme value estimation of bridge vehicle-induced load effect were proposed in this paper. Then, taking a simply supported T-beam bridge as an engineering application example, the extreme value of vehicle-induced load effect of bridge under random traffic flow load was estimated. Research conclusions: (1) K-S test automatically selects the threshold, which effectively solves the problem of difficult threshold selection of generalized Pareto distribution. This method has high computational efficiency and effectively avoids the truncation of GPD model. (2) The GPD model has a good fitting effect on the superthreshold samples of vehicle-induced load effect of the bridge, and it is effective and reliable for the extreme value estimation of vehicle-induced load effect. (3) The extreme value of vehicle-induced load effect of bridge increases with the increase of return period. Under the free traffic load, the extreme value of the load effect of the main beam at the carriageway of the multi beam simply supported beam bridge is greater than that of the main beam at other locations, and the first overload failure probability of side beam is the largest. In order to ensure the operation safety of the bridge in the future service period, similar bridges can improve the safety reserve of the main beam in the carriageway during construction, and take appropriate traffic control measures according to local conditions during operation.(4)The proposed method can be used in bridge safety assessment, life prediction and repair and reinforcement, and is convenient to be applied in practical engineering.
		2022 Vol. 39 (3): 69-74 [Abstract] ( 2172 ) HTML (1 KB) PDF (1100 KB) ( 1840 )

Main Line: Tunnel Engineering

	75	Research on the Control Technology of Over-under-excavation of Tunnel Blasting in Interbedded Rock Masses
		DING Xiang
		Research purposes: The poor interlayer cementation and low overall stiffness of interbedded rock masses make it easy for over-under-excavation problems to occur during tunnel drilling and blasting. In order to investigate the influence of interlayer rock on tunnel blasting over-under-breaking, this paper takes the interlayer section of Jianshan tunnel project of new Zhongwei-Lanzhou dedicated passenger line as the research object, and uses discrete element numerical simulation method and laser scanning image to analyze the influence of interlayer dip angle and thickness on tunnel over-under-excavation, based on which the optimization plan of gun hole arrangement is proposed. Research conclusions: (1) The problem of over-excavation in smooth blasting of interlayer tunnels is prominent, the over-excavation is mainly on the right side of the tunnel when the interlayer is left inclined, and the over-breaking is serious at the position where the direction of stress wave propagation is perpendicular to the direction of the structural surface. (2) The over-breaking at the top of the arch is the largest when the interlayer is close to horizontal, and the maximum over-excavation position shifts from the top to the foot as the inclination of the interlayer increases. (3) The increase in the thickness of the interlayer is beneficial to the stability of the surrounding rock, and the average amount of over-breaking after the layer thickness exceeds 0.7 m can meet the requirements of the specification, and it is recommended that the design of the hole must be optimized when the layer thickness is less than 0.7 m. (4) Through the optimization of hole arrangement around the location of easy over-breaking, the tunnel profile is formed more smoothly, and the maximum linear over-breaking is reduced by 60 cm, and the average over-breaking is reduced by about 36 cm. (5) The research results can provide reference for the control of over-under-breaking of smooth blasting in interbedded rock tunnel.
		2022 Vol. 39 (3): 75-80 [Abstract] ( 3926 ) HTML (1 KB) PDF (911 KB) ( 1908 )

	81	Risk Mechanism and Assessment of Large Deformation in Soft Rock Tunnel
		YANG Jianhui, SHEN Kai, SHU Lushan, XUE Yadong, WANG Jianjiang
		Research purposes: In high geostress tunnels, the occurrence of large deformation of soft rock has great uncertainty, which is a major difficulty in risk assessment. In order to accurately and effectively assess the large deformation risk of soft rock tunnels, a hierarchical evaluation method for large deformation is proposed based on Bayesian network (BN). Relied on the Yuntunbao tunnel, soft rock large deformation risk database is established and the six major risk sources are identified and reasoned. Research conclusions: (1) The large deformation of soft rock in tunnel is the result of multi factor coupling. By establishing the risk database, the mechanism is divided into two aspects: surrounding rock stability and support stability, and the Bayesian network model and a priori probability are established; (2) Through Bayesian sensitivity analysis, the key factors about the large deformation in soft rock tunnel are integrity of surrounding rock, support strength, ground stress, rock strength, construction method and tunnel shape; (3) Through the update of the risk database during the construction, the Bayesian network can well predict the probability of large deformation of the soft rock during the construction period.
		2022 Vol. 39 (3): 81-86 [Abstract] ( 3278 ) HTML (1 KB) PDF (805 KB) ( 1879 )

	87	Numerical Analysis and Application of Elliptical Bipolar Linear Energy-gathering Hydraulic Control Blasting Based on SPH-FEM
		WU Bo, LI Hualong, MENG Guowang, XU Shixiang, ZHANG Jinglong, CUI Yaozhong
		Research purposes: To reduce the influence of blasting activities on the tunnel environment, reducing the concentration of dust generated during blasting, while enhancing the blasting effect on the excavation area, the energy-gathering hydraulic blasting is often used. This paper simulates and verifies the gradual evolution process of the elliptical bipolar linear energy-gathering hydraulic blasting through numerical simulation and field engineering experiments in Jinjing railway tunnel, and analyzes the action mechanism and damage evolution process of energy-gathering hydraulic blasting. Research conclusions: (1) The development of cracks near the borehole has a certain tendency under the energy-gathering hydraulic blasting, enhancing the crack propagation in the energy gathering direction while restraining the development of cracks in other directions. It can enhance the blasting effect in the borehole by adding water. (2) By comparing hydraulic blasting three forms energy-gathering structure, the damage caused by the upper hydraulic energy-gathering blasting structure is mainly concentrated near the borehole, and the lower hydraulic energy-gathering blasting structure causes great damage to the hole bottom. And the damage area produced by the two-way hydraulic energy-gathering blasting structure is uniform, the falling stones have a higher degree of crushing, and the water medium can reconcile and neutralize the dust generated during the blasting process. (3) According to the above, the best blasting effect can be achieved by the construction of two-way hydraulic energy-gathering hydraulic control blasting of tunnel construction.
		2022 Vol. 39 (3): 87-93 [Abstract] ( 2305 ) HTML (1 KB) PDF (828 KB) ( 1890 )

Main Line: Communication Signals

	94	Research on the Train Control System Based on Virtual Coupling
		ZHANG Youbing, LIU Ling
		Research purposes: The railway block technology has developed from the fixed block, the quasi-moving block to the moving block, and the train tracking interval is getting smaller and smaller, which improves the railway transportation efficiency. However, the existing blocking technologies are based on the idea that the train ahead is stationary. Even if the moving block technology with the highest driving efficiency is adopted, the tracking interval between the behind train and the front train at least includes an emergency braking distance and a protection distance. However, the running speed of the existing high-speed train has already exceeded 300 km/h, and the emergency braking distance at high speed is very long, resulting in a long tracking distance between the behind train and the front train. In order to further shorten the train tracking distance and improve the transportation efficiency, it is necessary to break through the inherent concept of the existing blocking technology, and study and design the train control principle and key technologies of the train control system. On the basis of studying the existing blocking technology, this paper puts forward the key technologies and train control strategy of the train control system based on virtual coupling. Research conclusions: (1) In the train control system based on virtual grouping, the front train and the behind train establish train-to-train communication, and the behind train calculates the dynamic safety tracking distance according to the real-time speed, position and other state information of the front train, thus greatly shortening the tracking distance of the front and behind trains and improving the transportation efficiency. (2) The train control system based on virtual coupling needs to have key technologies such as train-to-train communication, train integrity check, accurate train positioning, dynamic safe tracking distance calculation, automatic tracking operation, in order to realize safe and efficient train tracking operation. (3) The tracking strategy of the front and behind trains is put forward. Based on the real-time state of the front and behind trains, the behind trains automatically accelerate, decelerate or run at a constant speed, and the tracking state of the front and behind trains is adjusted in real time to realize virtual grouping. (4) The research results can provide reference for the research on the principle and key technology of train control system in the future.
		2022 Vol. 39 (3): 94-100 [Abstract] ( 2810 ) HTML (1 KB) PDF (710 KB) ( 2163 )

	101	Design of Switch Control Circuit Based on the Multi-interlock Sharing
		ZHONG Zhiwang, CHEN Jianyi
		Research purposes: To realize 4 sets of interlocking shared control of 1~4 sets of switches in the signal comprehensive experiment and training base of railway bureau. On the basis of switching between interlock and outdoor turnout and safe control, it can reduce repeated construction of outdoor and indoor equipment, minimize the occupation of construction site, and save construction cost. Research conclusions: (1) A switching circuit is designed between interlock and switch interface circuit to realize the shared control of multiple interlocks on the same set of switches. (2) Four switch buttons are designed for each set of interlocks to achieve one-click switch. (3) The circuit is designed to indicate which set of interlock is currently connected. (4) All relays of the switching circuit are designed to connect the default interlock when they fall down, so as to ensure that at least one interlock can control the switch normally when the switching circuit fails. (5) The switching circuit fully considers the physical mutual exclusion between multiple sets of interlocks, so as to ensure that only one set of interlock control outdoor switch at the same time. (6) A switch synchronous inspection circuit is designed to check whether the switch control and switch representation are controlled by the same set of interlocks. (7) The application in Changsha experiment and training base shows that the circuit design meets the need of realizing multi-interlock shared switch control in signal comprehensive experimental and training base.
		2022 Vol. 39 (3): 101-106 [Abstract] ( 3969 ) HTML (1 KB) PDF (439 KB) ( 1881 )

Urban Railway Development and Technology Research

	107	Thoughts on the Concept and Some Problems of Urban (Suburban) Railway in China
		LI Ming
		Research purposes: The development of city railway (commuter railway) in some foreign cities has become mature, the development of urban (suburban) railway in China is still in the exploratory period. In recent years, many domestic scholars have paid more attention to city railway (suburban railway), and some problems about urban (suburban) railway in China have not yet formed a more unified understanding. This paper analyzes the national policies and concepts, construction mode, technical standards, resource sharing, planning requirements and other aspects, and puts forward relevant opinions. Research conclusions: (1) The name is not important, but the function orientation, service level and service scope are important. (2) The construction mode should not copy the foreign experience, but should flexibly choose the mode of utilization of existing railways or reconstruction of railways, or even combine them, and should do a good job in the integration along the railway. (3) The railway system, urban rail transit system and even combination system can be selected, polarization should be avoided, and ground laying should be adopted as far as possible. (4) Resource sharing is necessary, but the necessity and possibility of cross line operation are questionable. (5) Diameter line should be preferred, urban central radiation is acceptable due to engineering conditions, and the problems of whether the urban (suburban) railway exists or not should be solved first, and then the promotion should be solved.
		2022 Vol. 39 (3): 107-111 [Abstract] ( 3960 ) HTML (1 KB) PDF (407 KB) ( 1887 )