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Experimental Research on the Effect of Repeated Drying-wetting Cycles on the Mechanical Properties of Remolded Unsaturated Loess

MA Xuening, ZHANG Yuqin, ZHANG Peiyun, WANG Xu

Journal of Railway Engineering Society. 2022, 39(1): 1-6.

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Research purposes:Under the action of the repeated cycles of rainfall and evaporation, the water and gas state in shallow layers are in dynamic variation, which will have an irreversible effect on the mechanical properties of soil. In this paper, the SWCC curve test and triaxial test of remolded unsaturated loess after different times of dry-wet cycle were carried out. The effects of dry-wet cycle on water-holding capacity, strength and deformation characteristics of unsaturated loess were studied.
Research conclusions:(1) There is an obvious hysteretic phenomenon for the soil-water characteristic curve of unsaturated loess, which is gradually diminished with the increase of the times of dry-wet cycle. (2) The more suitable SWCC empirical model for unsaturated loess is VG model, and then the SWCC prediction models for loess under different dry-wet cycle times are established based on the VG model. (3) The stress-strain curve profiles are transformed from the strain hardening type to the strain softening type due to wet-dry cycle, the initial shear stiffness after wet-dry cycle is larger than that of the initial specimens, nevertheless, the failure strength is smaller. (4) With the increase of dry-wet cycle times, the effective cohesion c′,effective friction angle φ′and the suction friction angle φ^b of unsaturated loess are all decreased gradually. By comparison, the dry-wet cycle has the most effect on the effective cohesion, followed by effective friction angle, and the suction angle is affected least. (5) The research results can provide a reference for the selection of strength parameters in slope engineering design and reinforcement in loess area.

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Dynamic Response and Long-term Settlement of Heavy-haul Railway Embankment in Loess Area

WANG Rui, HU Zhiping, WANG Lei, BAI Lan, ZHAO Zhenrong

Journal of Railway Engineering Society. 2022, 39(1): 7-12.

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Research purposes:Field test is a significance way describing the dynamic response of subgrade under moving train loading. In order to obtain the dynamic stress distribution in the embankment at loess region, the field test was carried out with a heavy haul train passing through, and the characteristics of the dynamic stress curve and its evolution rule were discussed. Additionally, the long-term settlement of embankment was predicted.
Research conclusions:(1) The waveform of dynamic stress could be classified into three types, i.e. bimodal type, sine type and deflected sine type. Moreover, the two loading patterns of dynamic triaxial test were also proposed, i.e. "short intermission + sudden transition" pattern and "continuous loading + gentle transition" pattern. (2) The ratio of peak dynamic stress versus axial weight under various working conditions is within a specific envelope range. Boundaries of the envelope range could be defined by exponential function. (3) During the 50 years of operation, the dynamic settlement of embankment could not exceed 45 mm in the present study. (4) The research results can provide reference for the service status study of railway embankment under moving train loading.

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Research on the Line Smoothness Monitoring Technology of Subgrade Grouting of High-speed Railway in Operation Period

YUE Zurun, JIE Shaolong

Journal of Railway Engineering Society. 2022, 39(1): 13-17.

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Research purposes:In China, the subgrade of high-speed railway is widely distributed across soft soil, and due to constructions, sealing measures, micro-geomorphologic drainage and other reasons, it is easy to cause the subgrade to soften, produce settlement diseases, and reduce the operation benefits of high-speed railway. Therefore, in the courses of grouting reinforcement and renovation of the subgrade, in order to avoid the track geometry dimension exceeding the limits, it is necessary to construct a high-precision, real-time online line smoothness monitoring technology to provide technical support for grouting reinforcement of high-speed railway subgrade under operating conditions.
Research conclusions:(1) The precision of the miniature precision prism and the Leica TS15 automatic monitoring system can meet the requirements of all-weather monitoring and can be controlled within ±0.5 mm after the parameters such as temperature, humidity and air pressure are modified. (2) Indoor wind tunnel test and field test verify the safety and applicability of the micro precision prism installed on the rail waist and the side of the rail plate, which does not affect the normal operation of the high-speed trains. (3) The energy consumption tests of the automatic monitoring system show that the combination of portable power source and Internet of Things technology can realize automatic continuous monitoring during the grouting reinforcement process of high-speed railway subgrade, and its accuracy, operability and stability can meet the requirements of operation lines. (4) This technology in this paper has reference values in other similar operating conditions of high-speed railway.

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Model Experimental Research on the Temperature Stress of Low Vacuum Pipeline Structure

LV Qianqian

Journal of Railway Engineering Society. 2022, 39(1): 18-24.

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Research purposes:The high speed operation of maglev train can cause temperature increment of low vacuum pipe, which makes the temperature stress become an assignable structure load. So it is necessary to carry out experiment about structure temperature stress to determine the feasibility of the structure. At the same time, the temperature stress analysis method also needs to be studied based on the small size resistance strain gauge. In this paper, the test platform of low vacuum model pipeline structure was set up for the experimental study, and the temperature stress analysis method was discussed based on the data directly observed by resistance strain gauge.
Research conclusions:(1)The actual deformation of measured structure, thermal expansion coefficient and temperature coefficient of resistance strain gauge codetermine the resistance strain gauge reading under temperature load.(2)When the temperature of pipe inner wall is above 50 ℃, the constraining force around the outer wall circumference are in strong-weak cycles. When the inner wall temperature reaches 60 ℃, the temperature tensile stress reaches about 5 MPa, which needs to be pay more attention to.(3)The strain correction formula and the stress calculation formula can provide the basis for the temperature stress analysis based on the strain gauge observation data. (4)The experimental results can provide reference for pipe selection and temperature control of low vacuum pipeline transportation system.

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Effect of Temperature Gradient Load on Interlayer Damage of CRTS Ⅱ Slab Track

GAO Jianmin, JIN Zhongkai, LAI Sicheng

Journal of Railway Engineering Society. 2022, 39(1): 25-32.

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Research purposes:To investigate the influence of temperature gradient loads on the connection between mortar layer and track slab, a finite element model including a cohesion model between layers of CRTS Ⅱ slab ballastless track was established. The influence of positive and negative temperature gradient loads on the initiation and development of mortar layer gap and the effect of them on track deformations were analyzed. The difference between the two kinds of temperature gradient loads on interlayer damage was compared.
Research conclusions:(1) The damage area and deformations of CRTS Ⅱ slab ballastless track increase with the increase of temperature gradient loads. The interlaminar damage caused by negative temperature gradient loads are more serious than that caused by positive ones. (2) When the temperature gradient load is in the range of -10 ~20 ℃/m, it has little effect on the interlaminar damage. (3) Under the same temperature gradient loads, the deformation of track slab is greater than that of mortar layer. Under the positive temperature gradient load, the track structure deformation along the slab edge is greater than that along the slab middle. However, under the negative temperature gradient load, the difference is not significant. (4) The research results can provide theoretical reference for the long-term service performance analysis and maintenance of CRTS Ⅱ slab track of high-speed railways.

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Research on the Train Loading Length on Kilometer Level Railway Suspension Bridge

LU Wenliang, PI Fuyan, CHEN Liangjiang, ZHOU Yongzheng

Journal of Railway Engineering Society. 2022, 39(1): 33-38.

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Research purposes:When the main span length of kilometer level railway suspension bridge exceeds the maximum train formation length of the railway line, it is necessary to study the reasonable train loading length because the loading mode of the full bridge loaded by train load is not conformity with the actual train load during the service period of the bridge. A railway suspension bridge under construction is taken as the research object, the influence lines of internal force and displacement of the main components are calculated by finite element method. Based on the actual train length, the influence of train loading length on the force characteristics of each component is studied.
Research conclusions:(1) The internal force and displacement influence lines of main cables, suspender and main towers are all positive or negative within the range of main span; The positive length of main truss and lateral bracing internal force influence line and the positive length of the stiffness beam displacement influence line are about half of the length of the main span; The internal force influence line values of sway bracing and bridge decking have peaks in about five inter-section ranges near them. (2) With the increase of the loading length of the train, the increase range of internal forces and displacements of members decreases gradually. (3) Considering the actual train length and the variation rule of stress characteristics of members with the loading length, it is suggested that the train load loading length of suspension bridges should be 550 m. (4) The research results can provide guidance for theoretical research and engineering design of kilometer level suspension bridge.

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Experimental Research on the Static and Dynamic Performance of Trough Girder in High Speed Railway

LI Xuebin, MENG Xin, ZHOU Wenwu, LIANG Xinhua, MA Xizhang, MA Lin

Journal of Railway Engineering Society. 2022, 39(1): 39-46.

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Research purposes:In order to effectively use the main beam of trough girder to provide wind-retaining effect, prefabricated simply supported trough girders are widely used in 100-kilometre wind area of Lanzhou-Urumqi high speed railway in Xinjiang. Through bending static load test, transverse static load test in floor and driving test of EMU, bending rigidity, crack resistance, transverse tensile strain, natural frequency, dynamic coefficient, dynamic gain, rotating angle, amplitude, vibration acceleration of trough girder were analyzed, and the static and dynamic performance of trough girder was verified, to provide basis for subsequent design optimization.
Research conclusions:(1) In order to simulate the bending moment and torque of the mid-span section of trough girder synchronously in bending static load test, the method of the same longitudinal loads and different transverse loads at the loading points of webs on both sides can be adopted. (2) When the section or load of trough girder is asymmetric, the deflection of the webs on both sides can be converted to the centroid of the section to obtain the vertical deformation caused by the pure bending of the structure. (3) The bending rigidity and deflection and span ratio of trough girder under static and live load are two different values. (4) The actual bending rigidity of trough girder is greater than the design rigidity, and the crack resistance meets requirements in codes. The bottom plate is safe under the vertical load. (5) Under the load of EMU test train, the dynamic performance of trough girder meets the requirements of related acceptance standards for EMU running at 250 km/h and below. (6) The research results can provide reference for design optimization and related experimental study of trough girder.

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Experiment on the Soil Resistance behind Abutment of Semi-integral Abutment Jointless Bridge under Ambient Temperature

HUANG Fuyun, ZHOU Zhiming, SONG Dadong, YAN Aiguo, ZHANG Feng

Journal of Railway Engineering Society. 2022, 39(1): 47-55.

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Research purposes:Semi-integral abutment jointless bridge (SAJB) is a new type of bridge structure. Due to the rigid connection of main girder and abutment, the main girder will induce the bridge abutment to undergo reciprocating displacement along the longitudinal bridge direction, which results the changes of soil resistance behind the abutment under the long-term effects of diurnal and seasonal ambient temperature. In order to study the distribution law of the soil resistance behind the abutment and the influence of the medium long-term ambient temperature on it, a quasi-static test of the semi-integral abutment-soil interaction was carried out under medium and long-term ambient temperature.
Research conclusions:(1) The soil resistance with the ambient temperature rises rapidly in the 1st to 6th middle period (the first warming interval from spring to summer), then decrease in the 6th to 16th middle period (the period from summer to summer). In the 16th to 20th middle period (the second warming interval from winter to spring), it starts to increase again, but the increase rate is slightly slow compared to the first warming interval. (2) The soil resistance along the buried depth increases firstly until reaching the maximum at the buried depth of 0.8h, and then decreases under the medium long-term ambient temperature. (3) The law of soil resistance along longitudinal direction in each period is that in the area near the abutment, the soil resistance decreases rapidly; while in the area far away from the abutment, the soil resistance decreases slowly to 0 at the position 1.0h away from the abutment. (4) After a large period of ambient temperature, the soil resistance behind the abutment has a significant cumulative increasing effect, and its cumulative effect has a strong correlation with the longitudinal position and vertical depth of the soil. (5) The research results can provide references for the design of semi-integral bridges and the formulation of related specifications.

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Research on the Key Technology of Construction of Moving Formwork for Double-width Parallel Box Girder

WANG Jie, QIAN Youwei

Journal of Railway Engineering Society. 2022, 39(1): 56-60.

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Research purposes:The moving formwork cast-in-situ box girder construction technique has been applied to many projects at home and abroad. At present, it is mainly the single-width moving formwork. In the case of cast-in-situ box girder with double width and small spacing, ordinary conventional single-width moving formwork construction is limited by the beam width, in the construction of the second picture box girder, the formwork cannot be moved longitudinally, and the use scope is limited. Therefore, through the research on the construction technology of the 50 m double-width cast-in-place box girder of Lingkun super bridge of Wenzhou Railway Line S1, this paper aims to form a set of key construction technology of the double-width parallel cast-in-place box girder.
Research conclusions:(1) The finite element calculation results of the key components of the double-width parallel box girder moving formwork are in good agreement with the measured data of the preloading test; (2) The concrete pouring sequence of the moving formwork of double-width parallel box girder is reasonable, and the layout of the pouring equipment, the concrete conveying mode and the longitudinal movement mode of the formwork meet the construction needs; (3) Innovative design of double-width parallel making box girder moving formwork structure, use of folding the inner and outer formwork and bottom formwork for many times, realize the parallel manufacturing of the near distance box girder double beam, and the formwork tail is equipped with transverse adjustment cylinder, which solves the problem of small radius curve passing through holes; (4) The research results can provide reference for the design and construction of other similar projects.

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Research on the Temperature Distribution Law in Super-long Tunnel with High Altitude and Large Elevation

ZHENG Bo, WU Jian, ZHENG Jinlong, TAO Weiming, GUO Rui, LENG Xiqian

Journal of Railway Engineering Society. 2022, 39(1): 61-66.

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Research purposes:As the construction of the Sichuan-Tibet Railway progressing, the number of domestic super-long tunnels with high altitude and large elevation is soaring sharply. Because the current temperature distribution law in super-long tunnel with high altitude and large elevation is still unclear, it severely restricts its thermal insulation and anti-freezing design. If improperly fortified, the freezing damage will occur and furthermore, it will affect the operational safety. In this paper, taking the existing super-long tunnel with high altitude and large elevation as an example, the meteorological monitoring data inside and outside tunnel before and after construction are utilized to study a temperature distribution law and its influences on thermal insulation and anti-freezing length, and the relevant suggestions for thermal insulation and anti-freezing design are given by means of on-site monitoring, numerical simulation and other methods.
Research conclusions:(1) During the construction of tunnel, the temperature near tunnel face ranges from 13 °C to 16°C all year around and basically, it remains constant and less-affected by the temperature outside tunnel. The temperature value is mainly determined by the temperature of the surrounding rocks. (2) After the completion of tunnel, the longitudinal temperature distribution in tunnel are changed significantly and affected dramatically by the meteorological environmental conditions outside the tunnel. The "chimney effects" of the super-long tunnel with high altitude and large elevation is obvious. (3) The super-long tunnel with high altitude and large elevation will create a one-way natural ventilation from lower opening to higher opening, causing that the negative temperature length of the lower opening is apparently longer than that of higher opening and the temperature fields at both ends of the opening are asymmetrically distributed. (4) The research results can provide a reference for the construction of high-altitude tunnels with large elevation difference between lower and higher openings in Sichuan-Tibet Railway.

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Sensitivity Analysis of Flexible Shield Structure under Rockfall Impact

LIU Chengqing, GUO Haoyu

Journal of Railway Engineering Society. 2022, 39(1): 67-72.

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Research purposes:The flexible shield is a passive protective structure for slopes to intercept falling rock. With the characteristics of convenient construction, economical cost and environmental protection, the flexible shield structure is widely used in the rockfall disaster protection field. However, there are no codes to guide the design of the flexible shield structure. In this paper, three models such as the failure model of the flexible shield structure under rock impact are established based on energy method, Sobol' global analysis method is used to obtain the first-order sensitivity and global sensitivity of the flexible shield structure parameters, and an optimal design idea of the flexible shield structure is proposed.
Research conclusions:(1) The same parameter has different sensitive degrees in different calculation models; (2) The interaction between the parameters is obvious, and the global sensitivity of all parameters in the three models increases in different degrees compared with the first-order sensitivity; (3) In the flexible shield structure failure model, the smaller adjustment of high sensitivity parameters including the limit distance of falling rock and the equivalent cross-sectional area of cable can make the structure meet the design requirements and minimize the increase of steel consumption; (4) The research results can be used in the optimal design of the flexible shield structure, making structure design more economical.

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Analysis of the Influence of Tunnel Blasting Construction on Initial Concrete

TANG Xianxi, XIA Dingding, LI Danhe, WANG Yaowu

Journal of Railway Engineering Society. 2022, 39(1): 73-78.

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Research purposes:Relying on the Shenjiaba No. 1 tunnel of the Chengdu-Kunming railway double line, this paper establishes an experiment on the damage of the initial concrete when the tunnel is drilled and blasted, to analyze the damage of the initial concrete by comprehensive experiments and numerical values. The model is calculated to obtain the safe vibration velocity threshold of the initial concrete to ensure the safety and reliability of the initial concrete during tunnel construction.
Research conclusions:(1) The blasting vibration monitoring test is carried out in Shenjiaba No.1 tunnel. The Sadovsky empirical formula is analyzed by regression analysis. Combined with the numerical model of tunnel construction, the obtained results are compared with the calculated results of Sadovsky empirical formula, and the Sadovsky empirical formula of combined vibration speed is corrected to v_合=78×(3Q/R)^1.38. (2) Taking C25 initially supported concrete used in site construction as the object, the damage experiment of initially supported concrete under blasting is carried out, the damage value of concrete at different ages is measured, and the safe vibration velocity threshold of concrete at different ages is obtained. (3) The technical parameters of the initial concrete from this paper have guiding significance for other similar projects.

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Parametric Construction on the Mathematical Model of Parking Lanes Arrangement of Railway Station

HAN Yuanli, HAN Guoxing

Journal of Railway Engineering Society. 2022, 39(1): 79-83.

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Research purposes:The layout of train parking lanes is an important part realization of station automation design. This paper aims to establish a mathematical model for the automatic layout of the standard station parking lanes, and provide real-time parameterized modeling. With baseline as a reference, a scientific mathematical distribution model is established based on the spatial topological relationship between parking lanes and baseline. This mathematical model is adjusted by parameters to realize the ability of rapid space layout design for parking lanes on general standard station. The distribution model is based on the baseline of the track surface, and all calculations are based on mileage and left-right distance inference, and are loosely coupled with space, thus ensuring the synchronous support of the slope station and the curve station.
Research conclusions:(1) Based on the distribution characteristics of the parking lanes in standard station yard, a spatial distribution mathematical model for 6 sets 10 lanes including more than 120 control parameters was constructed. (2) Through the linkage deduction of multiple control parameters, the precise drive of the parking lanes distribution model is realized, which meets the needs of the station yard for rapid modeling and diversified parameter configuration. (3) The reliability and stability of this mathematical distribution model are verified by experiments and actual modeling effects, which provides an implementation method for the automatic station modeling of the 3D line selection design system, and has provided rapid modeling support for more than 50 stations in 20 engineering projects.

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Experiment Investigation the Seismic Behavior of Concrete Core Separation Composite Columns

PI Tianxiang, CHEN Zhaozhi, ZHAO Jianxin, WANG Sicheng

Journal of Railway Engineering Society. 2022, 39(1): 84-91.

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Research purposes:For the purpose of improving seismic behaviors of the cantilever columns, which are usually used in single-row column structures such as platform canopy and urban metro, the paper proposed a concrete core separation column composed of an inner column and an outer ring column, and put forward two types of connection columns with connectors and without connectors between the inner column and the outer ring column. We conducted the low-cycle reversed loading test of two large scale dimension specimens and numerical analysis with multi-parameters. The stiffness degradation, bearing capacity, ductility and energy dissipation of two columns were investigated, and the optimal design parameters such as the diameter ratio of inner and outer columns and the area ratio of longitudinal reinforcement were obtained.
Research conclusions:(1) The bearing capacity, energy consumption and elastic stiffness of the two core-separation composite columns are slightly lower than those of solid columns with the same reinforcement. However, when the concrete at the bottom of the column is broken, the damage of the inner column is less, and the yield of longitudinal reinforcement is significantly later than that of the outer column. The inner column can serves as the second seismic line of defense effectively. (2) Most of the concrete connectors in the column with connectors are in the plastic stress state and the initial stiffness is larger than that of the column without concrete connectors, but the energy dissipation capacity is slightly poor. (3) When the radius ratio of inner and outer circular columns is 0.4 and the reinforcement area ratio is 1 ∶2~1 ∶3, the two types of concrete core separation composite columns have better seismic behavior. (4) The relevant results can provide reference for the design of single column cantilever structure such as platform canopy.

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Research on the Key Technologies of Ontology-based Railway Engineering Master Data Management

XIE Yalong, YIN Xunxiao, LIU Yanhong , LIU Beisheng

Journal of Railway Engineering Society. 2022, 39(1): 92-100.

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Research purposes:The quality of railway engineering master data is related to the quality of the results of the overall railway engineering field informatization and intelligent construction, and it is the data base of the railway engineering informatization field. This paper analyzes the characteristics of railway engineering from the perspective of ontology, identifies the core master data classification in the field of railway engineering, focuses on analyzing the business relationship between data entities, and proposes the technical architecture, data structure and data service realization technical plan and path of the railway engineering master data management system, and at the same time, the management mechanism and method of railway engineering master data are proposed from a management perspective, which lays the foundation for the improvement of railway engineering informatization management level and the implementation of intelligent construction.
Research conclusions:(1) Apply ontology to identify the core data entities of master data in the railway engineering field. (2) Apply ontology to analyze the business relationship between master data in railway engineering, and analyze the composition and correlation of master data from the macro-management and micro-execution levels, and distinguish between sensitive entities and steady-state entities. (3) The technical architecture, data architecture, functional architecture and implementation route of a flexible railway engineering master data management system are proposed to provides technical mean for realizing the flexible and changeable management of railway engineering master data. (4) This paper puts forward the railway engineering master data management mechanism, which provides reference ideas for the development of railway engineering master data management from four aspects: management methods, process audit, data visualization and special team maintenance.

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Research on the Informatization and Intelligent Technology for High Speed Railway Track Engineering

WANG Senrong, QIN Yongping, MA Wan, LI Luyao

Journal of Railway Engineering Society. 2022, 39(1): 101-106.

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Research purposes:The intelligent technology of high-speed railway is the development direction of the industry. Combining with big data, cloud computing, Internet of Things (IoT), building information model and so on, this paper studies the informatization and intelligent technology and puts forward the implementation route for realizing the intellectualization of the whole life cycle of high-speed railway track engineering.
Research conclusions:(1) Combined with the characteristics of high-speed railway track engineering, this paper puts forward dynamic collaborative design, informatization and intelligent construction, and intelligent operation of track engineering. And the track intelligence platform is put forward, which includes intelligent management platform of China Railway, intelligent construction management platform of construction unit, intelligent construction information platform of construction organization and intelligent operation platform of railway bureau. (2) Aiming at slab track, the construction management intelligent platform has been built, informatization equipment and series of software has been developed, and digitalization, informationization and integration of track design, manufacturing and construction have been realized. (3) The research results have been comprehensively applied in Nanchang-Ganzhou, Shangqiu-Hangzhou and other high-speed railway projects. And it has realized digital design, construction quality and schedule control, information traceability, over-limit warning and so on, which has effectively improved the quality and efficiency of track engineering construction and achieved good results. (4) This research conclusion can provide reference for the realization of full life cycle informatization and intelligentization of high-speed railway track engineering.

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Research on the Selection and Tunneling Adaptability of Dual-mode Shield/TBM in Metro Tunnel

SONG Tiantian, LIU Chuankun, CHEN Fan, XU Yifan, WANG Shimin, HE Chuan

Journal of Railway Engineering Society. 2022, 39(1): 107-113.

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Research purposes:China′s metro construction presents the trend of geological environment complexity, so it is urgent to solve the problem of metro tunnel shield equipment selection under complex geological conditions. It is required to establish the selection principles according to the hydro-geological environment for shield/TBM dual-mode excavation equipment, while proposing a correction function for the interval mode of both project duration and cost. Based on the interval tunnel project of Shenzhen Metro Line 14, this paper analyzes the actual tunnelling speed of TBM and earth pressure mode in micro and medium weathered stratum and verifies the adaptability of dual-mode shield tunnelling in the composite stratum.
Research conclusions:(1) For the selection of dual-mode shield/TBM based on geological conditions, it is necessary to determine whether to select dual-mode according to the difference of stratum parameters and determine the section mode by the selection principle of single-mode shield, while considering other adverse geological conditions along the line. (2) The proportion of hard rock, soft rock uneven section and soft soil section in the whole section of the Buji-Shiyaling section of Shenzhen Metro Line 14 is 5 ∶3 ∶2. Combined with the selection principle of shield/TBM, it is suggested to adopt the earth pressure/TBM dual-mode shield TBM. (3) Based on the construction period and cost, the limit length of the transition of the slightly and moderately weathered strata is determined, and the section mode is modified. (4) The research results can provide the specific processes and methods for the selection of shield /TBM dual-mode tunneling equipment in metro tunnel.

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Research on the Dewatering Technology in Trapped Area of Shield Launching Shaft for Water-rich Sand Stratum

XIONG Zhongmin, QIN Zehong, ZHANG Ziguang, CAI Hong

Journal of Railway Engineering Society. 2022, 39(1): 114-120.

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Research purposes:In view of the technical difficulties of dewatering for trapped shield launching shaft in water-rich sand layer in Huai′an, Jiangsu Province, it is necessary to improve the calculation model of water inrush from foundation pit, to obtain the calculation method of confined water in foundation pit of shield tunneling well in water-rich sand stratum. The dewatering scheme is designed according to the improved method.
Research conclusions:(1) In consideration of two situations: confined water dewatering inside/outside foundation pit, the calculation method of water inrush and the dewatering funnel curve are respectively improved. (2) The scheme implemented by the improved method achieves the expected dewatering effect. The field measured data are consistent with the theoretical calculation and numerical simulation results, which verifies the rationality of the improved calculation method. (3) The effective implementation of improvement scheme for shield foundation pit of Huai'an Metro in Jiangsu Province can provide reference for dewatering of deep foundation pit with diaphragm wall enclosure structure in similar environment.

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15 January 2022, Volume 39 Issue 1

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15 January 2022, Volume 39 Issue 1