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2017 Vol. 34, No. 12
Published: 2018-01-15
Geology and Subgrade
Railway and Rail
Bridge Engineering
Urban Rail Construction
 
       Geology and Subgrade
1 Research on the Distribution Forms of Landslide Thrust after Anti-slide Pile
LI Mei, HE Guo-yu, HAN Gao-sheng, CHEN Guang-hai
Abstract：Research purposes： The size and distribution of landslide thrust is the main basis for the design of anti-slide pile structure, which directly affects the internal force and size of the pile structure, and there is a big difference in choices of the distribution mode of landslide thrust. In order to reasonably analyze anti-slide piles body force and thrust distribution, and to optimize the design of the anti-slide pile, based on the prototype of Gumuchong bridge slope of Hangzhou-Changsha railway line, the improved slice method, model test and numerical simulation are adopted to research the landslide thrust distribution of anti-slide pile.  Research conclusions： (1) The weakening coefficient of elastic modulus and the weakening coefficient of cohesion are introduced〖JP2〗 to weaken the mechanical parameters. The landslide thrust calculated by improved slice method of bidirectional〖JP〗 two slices, considering the lithologic difference of slideing body delamination, is more realistic. (2) Landslide thrust distributions obtained by the three methods are basically consistent. With the increase of buried depth, thrust of landslide after pile increases continuously and the whole distribution form shows a polygonal shape. The distribution forms of landslide thrust transit from the triangle (pile top to 1/2 buried depth) to the rectangle (1/2 to 2/3 buried depth) to trapezoid (2/3 buried depth to sliding surface) along the anti-slide pile and the maximum thrust locates at the sliding surface. (3) The research conclusions can be used as reference for the design of anti- slide piles in slope engineering. 
2017 Vol. 34 (12): 1-5 [Abstract] ( 4376 ) HTML (1 KB)  PDF  (607 KB)  ( 2828 )
6 Discussion of the Design Method for Slope (Landslide) Reinforced by Cable Anchors and Piles Hot!
JIANG Chu-sheng, ZOU Chuan, HUANG Xian-zhang, LI Qing-hai, SI Wen-ming, XU Ying
Abstract：Research purposes： The prestressed cable anchors and piles are often used in the design of high slope or landslide reinforcement. Cable anchors have become an irreplaceable measure in high slope reinforcement and landslide treatment because their adaptability, with deep active reinforcement, random reinforcement, good flexibility, convenient construction, etc. However, the existing calculation methods and design codes generally only list the calculation formula of a linear sliding surface, without a clear calculation method for the cable anchors and piles combination design. At present, most of the specifications only give calculation method for a single straight (bedding) surface. In practical engineering, the vast majority of sliding surfaces are non linear, and more for the broken line or arc surface. Because there is no formula directly, the designer can not analyze the joint force of anchor pile and slope using reasonable methods. The design works often relies on designers own engineering experience, lacking certain scientific basis. In this paper, the design methods of these measures which are usually used in landslide or high slope reinforcement were discussed. Research conclusions： (1) In this paper, starting with the calculation of slope stability coefficient and residual thrust, according to current specification formula, safety factor of broken line sliding surface and thrust undertaken separately by cable anchors and piles were deduced. (2) Other forms of sliding surface can all be simplified as broken line sliding surface, thus realizing reasonable design.(3) The calculation method proposed in this paper can be applied to railway, highway and other fields.
2017 Vol. 34 (12): 6-8 [Abstract] ( 4252 ) HTML (1 KB)  PDF  (306 KB)  ( 2654 )
9 Exploration on the Karst Geophysical Exploration Technology of the Railway Tunnel and Subgrade Base under Construction Hot!
LI Jian
Abstract：Research purposes： In November 17, 2013, Engineering Management Center of China Railway Corporation issued "the notice on carrying out karst exploration work of railway tunnel and subgrade under construction", which required carrying out the geophysical exploration in constructing railway tunnel and subgrade in karst area. In the past 3 years, we have carried out a large number of geophysical exploration work in the construction of Guiyang-Guangzhou railway line and other lines under construction, and made some effect, but there are also many problems, for example the geophysical results cannot meet the design requirement of karst disease treatment. This paper studies the existing problems, which will provide basis for correctly positioning the geophysical work and improving detection scheme of karst tunnel and subgrade in the future.  Research conclusions： (1) Because the site is difficult to have the prerequisite of geophysical exploration, the limitations of the selected geophysical methods and using geophysical exploration can not directly detect underground fissure water and other reasons, geophysical exploration of the railway tunnel and subgrade base under construction in karst area can only solve part of karst detection problems of the tunnel bottom and subgrade base. (2) The geophysical exploration belongs to the indirect exploration means, and in order to exclude multiple solutions of the geophysical exploration results, we should adopt comprehensive exploration methods in karst area, namely 30% geophysical anomaly excavation revealed or confirmatory drilling. (3) When validation data show that the karst is very developing, we should choose the cross-hole electromagnetic wave (seismic wave) tomography method to fine detection of karst, which provides reliable basic information for the subsequent design of tunnel and subgrade karst. (4) The research conclusion is applied on karst exploration in the railway tunnel and subgrade.
2017 Vol. 34 (12): 9-12 [Abstract] ( 6004 ) HTML (1 KB)  PDF  (508 KB)  ( 2674 )
13 Experimental Study of Super High Pressure Jet Grouting in Gravel Stratum Hot!
HU Qi-fan, ZHANG Ji-qing
Abstract：Research purposes： To solve the problem of water sealing and strengthening in ultra-deep and water-rich gravel stratum, the field test was carried out with the super high pressure jet grouting method, several sets of lock-joint or single high pressure jet grouting piles were constructed in the foundation pit which was under construction in Beijing, the diameter, strength and hydraulic conductivity of test piles and overlaps were measured in situ and by the experiments during the excavation of the foundation pit.  Research conclusions： (1) Large diameter piles can be formed by super high pressure jet grouting in ultra- deep and water-rich dense gravel stratum, the diameter of which can be larger than 1.5 m, the largest diameter in the experiment is 2.6 m.（2）Overlap between super high pressure jet grouting piles can be formed in ultra-deep and water-rich gravel stratum, of which the mean strength is over 10 MPa and hydraulic conductivity can reach to the level of 10-8 cm/s, which can fully meet the requirements of reinforcement or water sealing.(3) Super high pressure jet grouting technology is feasible in technique and suitable for ultra-deep and water-rich gravel stratum, the method can be used as an auxiliary method for reinforcement and water sealing in similar stratum. 
2017 Vol. 34 (12): 13-17 [Abstract] ( 6005 ) HTML (1 KB)  PDF  (2440 KB)  ( 2732 )
       Railway and Rail
18 The Main Technical Innovation of CRTS Ⅲ Slab Track for Zhengzhou-Xuzhou High-speed Railway Hot!
LI Qiu-yi
Abstract：Research purposes： Zhengzhou-Xuzhou High-speed Railway is the first test line for expanding application of CRTSⅢ slab track pretensioning prestressed slab in China. The design theory, structure design, construction materials, construction technology and other aspects of CRTS Ⅲ slab track require innovation. There are plenty of problems in interface optimization, slab manufacturing, turnout ballastless track slab, subgrade waterproofing layer optimization, self-compacting concrete preparation and construction, slab layout and fine adjustment that need further study. The research purpose of this paper is to develop and improve the CRTS Ⅲ slab track technology system of high-speed railway.  Research conclusions： (1)The complete technology system of CRTSⅢ slab track design, manufacture, and construction has been formed. (2) Since the operation of Zhengzhou-Xuzhou High- speed Railway, ballastless track has been in good condition, and the train has been running smoothly and comfortably. (3) The research results have an important significance in improving our competitiveness in the international market and carrying out the go global strategy.
2017 Vol. 34 (12): 18-23 [Abstract] ( 6214 ) HTML (1 KB)  PDF  (725 KB)  ( 2747 )
24 Research on the Geometric Parameters Optimization of W1 Fastening Clip Used in High- speed Railway
HU Lian-jun, YANG Ji-zhong, LI Zhong-ji, LIN Hong-song, FENG Du-bei
Abstract：Research purposes： As the key part of the fastening system, fastening clip is attracting more and more  attention to its structure design, performance analysis and parameters optimization. Taking W1 fastening clip commonly used in China high-speed railway as a research objective, by using DOE(design of experiment) method, the fastening clip's geometric parameters and their effects on the mechanical properties are studied in this paper. The parameters optimization is finally carried out, which has a certain significance on the shape design of the fastening clip.  Research conclusions： (1)There are 11 structural parameters of W1 fastening clip, which have influence on its service performance. The most significant effects on the service performance are: spring deflection T, diameter d, arch L0, unfolded drawing b2 and R2. (2)The main change of domestic ω-type elastic clip is to increase the deflection T, diameter d, and arch L0. However, Vossloh fastening clip adopts an approach of reducing b2 and increasing R2 to enhance the performance. (3)According to the response camber optimization design, with the spring deflection T and diameter d fixed, the optimal conditions of fastening clip are: arch span L0 is 80.12 mm, unfolded drawing R2 is 26.03 mm, unfolded drawing b2 is 32.79 mm. Results show that the clamping force is 10.049 kN, the maximum stress is 1 298 MPa, the optimization index W is 0.156. The clamping force and the maximum stress increases a little, but the material is more economical, the optimization index increases a little. Thus, the optimal fastening clip is better than the original W1 fastening clip. (4)DOE(design of experiment) could propose the optimal parameter combinations through the coordinated change of parameters in order to meet the design requirements of fastening clip. (5) The research results can provide a reference for the shape design optimization of other similar fastening clips.
2017 Vol. 34 (12): 24-30 [Abstract] ( 3490 ) HTML (1 KB)  PDF  (768 KB)  ( 2549 )
31 Effect Analysis of CRTSⅠType CA Mortar Degradation on Its Fatigue Life
XU Hao1, LIN Hong-song1, YAN Hua1, WANG Ping2
Abstract：Research purposes： Debonding between slab and cement asphalt mortar(CA mortar) layer is a typical damage of China Railway Track System (CRTS) Ⅰtype slab track and the CA mortar degradation will reduce its fatigue life under the train loading. In order to study the effect of CA mortar degradation on its fatigue life, the finite element model of CRTSⅠtype slab track was established in this paper, the stress and fatigue life of CA mortar were researched in different degradation situations on the basis of Miner linear fatigue cumulate damage rule, which could provide reference for the maintenance of slab track.  Research conclusions：（1）The stress and fatigue life of CA mortar decrease when the performance degradation of CA mortar layer is 50%, and the fatigue life of CA mortar could meet service life of 60 years.（2）When considering the debonding of CA mortar layer or performance degradation of 50% and debonding of CA mortar layer, the stress of CA mortar increases observably, the fatigue life of CA mortar decreases observably.（3） The fatigue life of CA mortar could not meet the 60 years of service life when the debonding length of CA mortar layer is 1.225 m.（4）The debonding length of CA mortar layer should not be exceed to 1.225 m. The maintenance should be strengthened in the service life of CA mortar, which can prevent the fatigue damage of CA mortar.（5）The research results can provide reference for the maintenance of CA mortar. 
2017 Vol. 34 (12): 31-34 [Abstract] ( 3269 ) HTML (1 KB)  PDF  (529 KB)  ( 2507 )
       Bridge Engineering
35 Research on the (110+198+110)m Rigid Frame Design of Fuzhou-Pingtan Railway
ZHAO Zhi-jun
Abstract：Research purposes： Minjiang is the inland waterway for grade II, single hole two-way navigable requirements are clearance of 170 m and height of 24 m. The main bridge span of Minjiang super large bridge of Fuzhou-Pingtan railway uses (110+198+110) m continuous rigid frame. Due to the large span of this bridge, it is a key project, and the bridge structure design must be selected in many directions. The beam depth, double thin-wall pier column spacing, double thin-wall pier thickness, arrangement of pile foundation, bridge structure were compared and selected combining with the navigation and geological situation, and the suitable bridge structure and outline size for the project were obtained.  Research conclusions： Based on the calculation and analysis of different selection conditions, we can draw the following conclusions: (1) The stress, displacement and other indicators of the main structure meet the specification requirements, and the outline dimensions of the bridge design is appropriate.(2) For the ballasted track continuous rigid frame within 200 m of the main span, the main span increasing steel truss beam, has little influence on the creep deformation of the structure after construction, but the cost will increase a lot, so it should not be used. (3) The research results are applied to the design and construction of Fuzhou-Pingtan railway, which can provide reference for similar engineering. 
2017 Vol. 34 (12): 35-39 [Abstract] ( 3298 ) HTML (1 KB)  PDF  (474 KB)  ( 2553 )
40 Research on the Full Length Cantilever Casting Construction Scheme of Concrete T- type Rigid Bridge with High-steep Rock Slopes
SUN Da-bin
Abstract：Research purposes： The cast-in-site section is commonly set at the end of the bridge, which constructed by cantilever casting method. It is far more difficult and costly to install the scaffold on the high-steep rock slopes, and the foundation treatment makes great impact on the environment. In order to solve those problems and continue to guide scheme design of similar bridge, a specific engineering of passenger dedicated railway is taken as the analysis object to make a deep research on the full length cantilever casting construction scheme.  Research conclusions： (1) With the length decrease of the cast-in-place segments of the bridge end, the amount of the prestressed steels of the T-type rigid bridge tends to be larger, however, it has little influence on the creep deformation and the reaction force. (2) For prestressed concrete T-type rigid bridges, the cost decreases when the length of the cast-in-place segments decreases, and the rate of cost reduction will be accelerated if the slope is steeper. (3) Using the full length cantilever construction scheme can effectively avoid the impact of construction on the environment. (4) The research results can provide a valuable reference for the design of T-type rigid bridge with high-steep rock slopes or other conditions, which are difficult to erect the support, such as flyover and cross river bridge. 
2017 Vol. 34 (12): 40-44 [Abstract] ( 3410 ) HTML (1 KB)  PDF  (598 KB)  ( 2586 )
45 Coupling Vibration Analysis on Wind-vehicle-bridge System Considering the Effects of Wind Yaw Angle Hot!
CHEN Ke-jian1，XU Xin-yu1， LI Yong-le2，SU Yan-wen1，ZENG Yong-ping1，ZHANG Jing-yu2
Abstract：Research purposes： The wind loads on the trains are not always cross-wind condition (90° wind yaw angle) due to the effects of air incoming, line structures and terrain conditions. In order to investigate dynamic responses of trains on typical railway bridges under wind loads, coupling vibration analysis of different yaw angles cases on aerodynamic characteristics of vehicle on the high-speed railway bridge was conducted, and the dynamic responses of vehicle were analyzed based on the established wind- vehicle-bridge system model using rigid-flexible coupling method. A 20 spans of 32 meters high-speed railway simply supported beam bridge was taken as the research object.  Research conclusions： (1) Drag coefficient of trains decreases with the decrease of wind yaw angle. (2) With the decrease of yaw angle, the lateral force, reduction rate of wheel load, derailment coefficient and lateral acceleration decline. The vertical acceleration has no obvious law, and value of vertical acceleration at the 90° wind yaw angle is the largest. (3) Under the cross-wind condition, each dynamic response is the largest, which leads to the most unfavorable situation for the train operation. (4) The research results can provide a reference for the coupling vibration analysis considering complex air incoming.
2017 Vol. 34 (12): 45-49 [Abstract] ( 6089 ) HTML (1 KB)  PDF  (815 KB)  ( 2569 )
50 Research on the Mechanism of Longitudinal Seismic Mitigation Devices for High-speed Railway Continuous Bridges
LI Xiao-bo
Abstract：Research purposes： In order to provide the basis for the longitudinal seismic mitigation design of long- span continuous bridges, based on a (60+100+100+60)m long-span continuous bridge, the seismic mitigation mechanism and effect of Lock-up device, fluid viscous damper and double spherical seismic bearing were studied comparatively in this paper, the main parameters that affect the seismic mitigation effect were analyzed, and then the reasonable parameter range and the applicable condition of seismic mitigation devices were discussed.  Research conclusions：（1）The lock-up device do not dissipate seismic energy, and it reduces the response of the fixed pier by changing the seismic force distribution path. But it will reduce the longitudinal vibration period of structure, leading to the increase of the internal force response of the structure, so the seismic mitigation effect for short pier is better.（2）Fluid viscous damper do not change the dynamic characteristic of the bridge structure, which mainly reduces the seismic response by hysteretic energy. (3) Double spherical seismic bearing lengthens the longitudinal natural vibration period, and it provides additional damping for structure by hysteretic energy, which obviously reduces the internal force of the fixed pier but increases the relative displacements between girder and pier. (4) The research results can provide reference for the longitudinal seismic mitigation design of long-span continuous bridge. 
2017 Vol. 34 (12): 50-56 [Abstract] ( 3373 ) HTML (1 KB)  PDF  (905 KB)  ( 2602 )
57 Design and Application of Shock Absorber for 48 m Simple Supported Box Girder Bridge of Baoji-Lanzhou Passenger Dedicated Line Hot!
FENG Ya-cheng
Abstract：Research purposes： High speed railway large span simple supported girder bridges in high seismic intensity area have remarkable characteristics with big mass, large span and difficult seismic design. Aniti-seismic needs could be satisfied by strengthening pier and pile concrete reinforcement under frequent occurred earthquake, but it is still a problem under rarely occurred earthquake to ensure the safety of the structure. The paper carries out research on 48 m simple supported box girder bridge in high seismic intensity area with 0.3g of Baoji-Lanzhou passenger dedicated line, and takes shock absorber as seismic isolation on the pier.  Research conclusions： (1) Adopting idea of "bearing function separation", shock absorber is a simple and advanced device which separates the bearing transmitting horizontal forces from vertical supporting completely, vertical forces and rotation are still realized by bearing, and horizontal forces and displacement are realized by shock absorber. (2) The damping efficiency of shock absorber varies with different pier height along bridge direction, when pier height≤12 m, the damping efficiency could be as high as 54% under frequent occurred earthquake, when pier height is 20 m, the damping efficiency is 29%, and the transverse damping efficiency is 43%~55%. (3) The earthquake forces applying shock absorber under rarely occurred earthquake could be reduced to a level which is equal to frequent occurred earthquake level; with the increase of pier height, rarely occurred earthquake forces that using shock absorb will be a little bigger than frequent earthquake forces without shock absorber. (4) The research result can provide references on large span bridge seismic isolation design and construction in high seismic intensity area in the future. 
2017 Vol. 34 (12): 57-62 [Abstract] ( 5517 ) HTML (1 KB)  PDF  (798 KB)  ( 2651 )
63 Railway Bridge Survey Information Processing System
LIAO Li-jian
Abstract：Research purposes： The schematic design of railway bridge survey directly determines the quality of construction drawing. The survey tasks cannot be finished with the disadvantages such as short construction period and few staff. Through the research algorithm, the problems of the schematic design for railway bridge are solved, and the technical support is provided for the automatic processing of bridge survey information.  Research conclusions： (1)The regional code is introduced to describe broken chain, breaking rule that the broken chain can not be on bridge. (2) The method of curve layout for continuous beam is put forward, and the iterative structure is added to curve layout calculation process. So the bridge with multiple curves can be laid on the curve for once. (3)The span arrangement is abstracted as an accumulated counter, which speeds up the scheme comparison. (4)The pier coordinates can be evaluated by using plane drawing of railway route, which makes seamless joint between railway bridge field and railway line field come true. (5)The problem of overlapped characters is solved by the recursive algorithm. (6) The optimized scheme in the system is reasonable and feasible. The system has the advantages of fast calculating speed and standardized output, and it can be applied to large-scale railway bridge survey and design effectively.
2017 Vol. 34 (12): 63-68 [Abstract] ( 4595 ) HTML (1 KB)  PDF  (1415 KB)  ( 2594 )
69 Research on the Wireless Bridge Health Monitoring System for High Speed Railway
ZHENG Mao-xiang
Abstract：Research purposes： In view of the problems existing in the current high-speed railway bridge health monitoring system in China, such as the difficulty of data acquisition, the low degree of automation of data acquisition and the low accuracy of data acquisition, a wireless bridge health monitoring system for high-speed railway based on ZigBee technology is designed by using the advantages of wireless sensor network, by changing the means and methods of data acquisition, the purpose of effectively improving the health monitoring level of high-speed railway bridges is achieved.  Research conclusions： (1) The wireless sensor network has the characteristics of target tracking for dynamic optimization of network nodes. When designing high-speed railway wireless bridge monitoring system, the locating of data acquisition nodes is flexible and convenient, and the network is reliable. (2) Using the communication function of the wireless network module, it can realize the efficient online real-time data acquisition and transmission.(3) Through the simulation experiment of wireless bridge health monitoring system network model, it is proved that the system is accurate, timely, reliable and efficient. (4) The system can be widely used in the actual monitoring of the health condition of high speed railway bridges.
2017 Vol. 34 (12): 69-72 [Abstract] ( 3273 ) HTML (1 KB)  PDF  (552 KB)  ( 2552 )
       Urban Rail Construction
73 Research on the Urban Rail Transit Design between Sub-center and Center of City
WANG Lin
Abstract：Research purposes： In the process of urbanization, the expansion trend of big cities brings many problems such as traffic congestion and environmental pollution. In order to guide the expansion type of the city from single center to multiple center, and achieve the sustainable development, the paper researches on the urban rail transit design between sub-center and center of city.  Research conclusions： (1)When designing the urban rail transit between sub-center and center of city, should strengthen the rail transit line planning between sub-center and center of city, give priority to use the quality routing resources, determine the urban rail network scale based on the passenger flow, determine whether need to lay out the express line according to the urban planning requirements. (2)For the urban rail transit between CBD and Sub-CBD, the subway system and the underground line is generally suitable. However, for the urban rail transit between sub-center and center of city, the general requirements are higher speed target value and larger station spacing, the laying mode is the ground line or elevated line, and should take full account of the TOD development strategy.（3）The research conclusion will provide theoretical guidance for the urban rail transit design between sub-center and center of city. 
2017 Vol. 34 (12): 73-76 [Abstract] ( 3430 ) HTML (1 KB)  PDF  (529 KB)  ( 2704 )
77 Research on the Track Laying Modes in North Section of Hohhot Metro Line 2
ZHANG Ben
Abstract：Research purposes： Urban mass transit project may encounter changes in the external boundary conditions during the planning and design phase. Combining with the characteristics of the project, according to the local condition, scientific and rational choice of track laying mode can optimize the allocation of urban space, also can maximize the comprehensive benefits of urban mass transit. Taking the engineering of Hohhot metro line 2 as an example, the influence of several different track laying modes on the use function and project cost is analyzed and compared in this paper, which include elevation laying mode, partial elevation laying mode, underground shallow laying mode and underground TBM laying mode, to provide technical support for modifying the laying mode in north section of metro line 2.  Research conclusions： (1) Combining with overall planning of the city, the urban landscape, the environmental impact, the conditions of project implementation, the station use function, the operating conditions, urban mass transit track laying mode should be determined after full economic & technical comparison and scientific selection. (2) Taking into account the engineering conditions and the implementation difficulty, the difference of costs between underground shallow laying mode and underground TBM laying mode is not obvious in this project. (3) The north section of Hohhot metro line 2 is recommended to use the underground TBM laying mode. (4) The research result can provide reference for the selection of similar engineering track laying mode. 
2017 Vol. 34 (12): 77-82 [Abstract] ( 3523 ) HTML (1 KB)  PDF  (996 KB)  ( 2596 )
83 Research on the Seismic Responses for Shield Tunnel in Liquefiable Soil
ZHOU Jun1，WU Wei-lin1，HU Rui-qing2
Abstract：Research purposes： In this paper, taking Foshan Metro Line 2 shield project as an example, the undisturbed soil and calculation parameters of soil reinforcement are obtained through field sampling of sand and dynamic triaxial test, which are calculated and analyzed using finite element analysis software ANSYS, the dynamic response and the formation  of liquefiable sand soil layer are quantified and evaluated in shield tunnel under horizontal seismic wave excitation the damping effect of reinforcement.  Research conclusions：(1) In the transverse seismic loading, strata and structural seismic response and seismic wave peak value is not synchronized in time, and the formation and development of the seismic response of the structure are different, the first principal stress maximum value of the lining is 1.69 MPa. (2) After taking the reinforcement measures of tunnel surrounding strata, the greater the stratum strength parameters is, the greater the decline of segment displacement is, and the greater the amplitude of principal stress increase (decrease) is, which can meet the operational requirements and strength of tunnel. (3) Considering the influence of shield tunneling process on adjacent buildings, it is suggested that the reinforcement of sand soil layer be reinforced with 400 kg superfine cement per cubic meter. （4） The research results can be applied to the seismic design and selection of reinforcement measures for the shield tunnel in liquefiable sand soil.
2017 Vol. 34 (12): 83-88 [Abstract] ( 5181 ) HTML (1 KB)  PDF  (637 KB)  ( 2666 )
89 Analysis on the Stability of Shield Underpassing Through Multiple Arch Bridge Repeatedly in Sandy Cobble Stratum Hot!
JIA Shao-chun
Abstract：Research purposes： Sandy cobble stratum has significant weak cementation, high sensitivity, and poor self-stability ability after disturbance, and there are few related engineering cases and researches on small clear distance shield tunnel underpassing through multiple arch bridge repeatedly in similar sandy cobble stratum. Based on shield tunnel of Chengdu metro line 5 and line 6 underpassing through multiple arch bridge, three dimensional finite element method is applied to analyze the influence of shield tunnel approaching excavation on displacement and internal force of multiple arch bridge in sandy cobble stratum, and the results are compared with that under condition of ground reinforcement, which provides theoretical guidance for the construction of shield tunneling.  Research conclusions：（1）When shield tunnel closely passes through multiple arch bridge which is not reinforced, the unreinforced bridge has large vertical and lateral displacements, the maximum displacement value is 3.92 mm and 0.52 mm respectively. The inhomogeneous settlement of pier and shield tunnel construction cause the axial force, shear force and bending moment of the arch bridge to change, and the maximum internal force occurs at arch foot.（2）For arch bridge foundation and surrounding strata of tunnel, grouting reinforcement can significantly reduce the overall displacement of the multiple arch bridge, the maximum vertical and lateral displacement of the bridge is 2.96 mm and 0.39 mm respectively, with a decrease of 24.5% and 25.0%, respectively. The axial force and shear force changes slightly, the bending moment value decreased significantly, decreasing by 13.1%. （3） The grouting reinforcement method can ensure the operation safety of multiple arch bridge during the shield tunnel construction, and the research results can provide theoretical guidance for the construction of sand cobble stratum shield tunneling.
2017 Vol. 34 (12): 89-94 [Abstract] ( 6477 ) HTML (1 KB)  PDF  (780 KB)  ( 4159 )
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