Table of Content

28 September 2013, Volume 47 Issue 09 Previous Issue    Next Issue

Mechanical instrumentation engineering

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Prediction of Friction Torque of Ball Screws Using a Creep Force Model CHEN Yongjiang,TANG Wencheng 2013, 47 (09):  1335-1340.  Abstract ( 1087 )   Save Being capable of predicting the friction torque of the ball screw accurately allows the designer to correctly determine the energy loss and heat generation rate. Based on the theory of creep, the sliding forces between the ball and and nut raceway were calculated, then a creepage analytical model for the ball screw was established. This model was used to analyze the quantitative relationship between the creepage/spin and the tangential tractions. The result shows that there exists non-linear incremental relationship between creep rate and friction, and the spinning motion will cause an additional traction transverse to the rolling direction. Tangential movement and the spin motion have a strong coupling effect. Finally, the ball screw tests were performed on a special machine, it was found that the predictions of the new analytic torque model are in good agreement with the test results.   References | Related Articles | Metrics

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Tribological Properties of Modified Poly-p-phenylene Benzobisthiasole Fiber Reinforced Thermoplastic Polyimide Composite YU Liang1,CHENG Xianhua1,2 2013, 47 (09):  1341-1346.  Abstract ( 878 )   Save Rare earth solution (RES) and coupling agent surface modification were employed towards poly-p-phenylene benzobisthiasole (PBO) fibers, and impact and tribological properties of the untreated and treated PBO/TPI composites were evaluated. The results show that both RES and coupling agent surface modification can improve the interfacial adhesion between PBO fibers and TPI matrix, and accordingly enhance the impact and tribological properties. Compared with the untreated and coupling agent treated PBO/TPI composites, the RES treated composite has better interfacial adhesion. The RES surface modification is the most effective one to improve the impact and tribological properties under the same test conditions. This is because that the ratio of oxygen/carbon on the surface of RES treated PBO fiber is the maximal one, which indicates the content of polar groups on the surface of PBO fibers increases compared with the others. The increase in the amount of polar groups could strengthen the interfacial adhesion between PBO fibers and TPI matrix effectively. References | Related Articles | Metrics

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Thermoelastohydrodynamic Lubrication Analysis of  Misaligned Plain Journal Bearings ZHANG Zhenshan,DAI Xudong,ZHANG Zhinan,XIE Youbai 2013, 47 (09):  1347-1352.  Abstract ( 1393 )   Save By the synthetic solution of the generalized Reynolds equation, three-dimension energy equation, and heat conduction equations and deformations of the solids, this paper developed the thermoelastohydrodynamic (TEHD) model of misaligned plain journal bearing (MPJB). On the basis, series of results were provided to examine the effects of elastic and thermal deformations on the performance of the MPJB. The results show that the elastic and thermal deformations have remarkable influence on the performance of the MPJB. The elastic deformation leads to the creation of the local “pocket” in the oil film thickness. Under this condition, the maximum oil film pressure decreases significantly. The thermal deformation gives rise to the emergence of the local “bowl” in the oil film thickness. Therefore, the minimum oil film thickness increases obviously. However, the influence of the thermal deformation on the maximum oil film pressure is very small. All properties of the bearing vary significantly for the complete TEHD simulation, thus, it is essential to develop the TEHD model for analyzing the bearing performance. References | Related Articles | Metrics

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Multivariable Robust Locating Scheme Design of Body Parts   ZOU Jingming1,CHU Guoping1,LIANG Shuyong2,YIN Guoli2 2013, 47 (09):  1353-1357.  Abstract ( 719 )   Save A robust locating scheme design was provided under the circumstance that only parts of A surface or initial structure are known in the initial design phase of a new vehicle model. An optimization design model of locating scheme was established based on the deterministic locating for rigid parts and robust design principles. The optimal locators are searched by using genetic algorithms in feasible region; the sensitivity coefficient which provides an indicator of how sensitive the assembly quality are to variance of locator is extracted, and finally tolerance optimization is achieved while costs are reduced. An example of locating design of a new vehicle model’s head-lamp was demonstrated, which proves that the method is effective in the initial design phase.   References | Related Articles | Metrics

Chemical Industry

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Mathematical Model of Pulverized Coal Ignition and Combustion Considering Various Pyrolysis Products QI Yongfeng1,ZHANG Mingchuan2,YU Juan2 2013, 47 (09):  1358-1362.  Abstract ( 792 )   Save The transient whole-coupling model in a spherical coordinate system on single pulverized coal pyrolysis and combustion was developed, taking into consideration various pyrolysis product release, heat transfer, mass transfer, and chemical reactions. The igntion and combustion characteristics of Shenmu bituminous coal were simulated. The result shows that the ignition of pulverized coal begins from volatiles, and the volatile flame can move rapidly to a position departing from the center of the coal particle by about 29 times radius, due to the limitation of oxygen diffusion; when the coal pyrolysis is completed, the CO generated by surface oxidation reaction has been ignited, the flame returns almost to the coke particle surface, the particle temperature rises abruptly, and the coke combustion is controlled by the surface oxidation reaction; with the combustion rate increasing, the coke combustion begins to be controlled by the surface reducing reaction, and the char flame departs from the particle surface again.   References | Related Articles | Metrics

Architechural Science

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Experimental Study of Influence of Hydroxy-aluminum/Polyaluminum on Mechanical Characteristics of Montmorillonite SUN Shiyong,YAO Hailin,DONG Qipeng,DUAN Jianxin 2013, 47 (09):  1363-1366.  Abstract ( 815 )   Save The hydroxy-aluminum/polyaluminum modified clay and the clay only samples were examined by X-ray diffraction (XRD), unconconsolidated undrained (UU) triaxial strength test, unconfined compressive strength testing techniques, swelling potential tests and so on. The results indicated that the hydrophilic nature and swellingshrinkage property were changed drastically, that the free swelling ratio (Fs) could be reduced sharply, and that the particle size gradation, strength characteristics of the modified montmorillonite clay were improved greatly. The clay content decreased dramatically, while the silt content increased. This study suggests that the hydroxy-aluminum/polyaluminum can influence the mechanical and physical properties of montmorillonite clay by physicochemical interaction.   References | Related Articles | Metrics

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Analytical Solution of Steady State Temperature Field of  Four Freezing Pipes in an Infinite Region HU Xiangdong,GUO Wang,ZHANG Luoyu 2013, 47 (09):  1367-1371.  Abstract ( 703 )   Save Based on the potential superposition theory, this paper gives analytical solutions to steady state frozen temperature of four freezing pipes arranged at random. Particular solutions are derived for some particular arrangements, such as four freezing pipes with rectangle arrangement and rhombus arrangement. Comparison of the analytical solutions with the numerical thermal analysis shows that the analytical solutions are precise enough.   References | Related Articles | Metrics

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Soil Arching Effect Analysis of Anti-slide Piles in Loose Media Landslide ZHAN Yongxiang1，YAO Hailin1，DONG Qipeng1，WANG Jiaqiang2，HE Dongping3 2013, 47 (09):  1372-1376.  Abstract ( 1049 )   Save Based on particle flow theory, the process of formation, development, destruction and re-formation of the soil arching in loose media landslide were systematically studied by using PFC2D program to analyze the effect of meso-mechanical parameters such as friction coefficient and porosity on pile-soil interaction characteristics. The results show that the soil arching produced by the anti-slide pile for the first time bears the ultimate bearing capacity; after the destruction of the soil arching, subsequent formation of the soil arching effect bears the residual capacity; the value of residual capacity fluctuates, but within a certain limit; the ultimate bearing capacity, the residual capacity and the maximum pile load distribution ratio decrease with the increase of pile clear spacing, and increase with the increase of pile width, yet the relation is not a linear one; the soil arching effect is greatly affected by the friction coefficient within a certain limit, and as the friction coefficient increases, the effect is more significant, the ultimate bearing capacity of soil arching is larger, and the maximum pile load distribution ratio tends to increase; soil arching effect is significantly affected by the porosity of particle aggregate, and the soil arch ultimate bearing capacity of low density loose landslide is equivalent to the residual capacity of high density loose landslide.   References | Related Articles | Metrics

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Strength of Sand Reinforced with Different Forms of Geogrid ZHOU Xiaofeng1,ZHANG Mengxi1,QIU Chengchun1,ZHU Hong2,WANG Jin2 2013, 47 (09):  1377-1381.  Abstract ( 942 )   Save Based on the polyester welded biaxial geogrid (PET25-25), different forms of geogrid were designed, such as uniaxial, biaxial, triaxial and multiaxial ones. By means of triaxial compression tests, the strength property and failure modes of these forms were obtained. Besides, the influence of the space between transverse ribs in uniaxial geogrid on the strength and the configuration of reinforcement inside the basic geogrid element were studied. It can be seen from the test results that different forms of geogrid had different reinforcing effects; the multiaxial geogrid had the best reinforcing effect, consuming the greatest amount of material, 2.21 times of the basic geogrid element; biaxial geogrids performed better in reinforcing than uniaxial and triaxial ones; the comparison of uniaxial geogrids and triaxial ones were different in different confining pressures, that is, in low confining pressure, uniaxial geogrids performed better than triaxial ones, in contrast, in high confining pressure, triaxial ones did better. In addition, the reinforcing effect of uniaxial geogrids increased with the space of transverse rib decreasing; uniaxial geogrids mainly improved the cohesion of reinforced sand, however, other forms of geogrid mainly increased the friction angle.   References | Related Articles | Metrics

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Particle Flow Modeling of Soil-Rock Mixtures In-situ Tests DONG Qipeng1,LU Zheng1，ZHAN Yongxiang1,WANG Jiaqiang2 2013, 47 (09):  1382-1389.  Abstract ( 932 )   Save The numerical simulation of soil-rock mixtures(S/RM) shear test was successfully performed using the particle flow theory based on particle flow code (PFC), by creating irregular clumps, constant normal stress and rock content in shearing surface. Based on the clump of PFC with different stone content, different normal stress of S/RM direct shear test simulation were elaborately discussed. The reliability of the simulation method was verified by comparing calculation results and in-situ shear test. The main research results indicate that with the increase of rock content, the shear stress and the peak shear stress increase, while the shear displacement at the peak shear stress decreases. S/RM samples exhibit shear dilatation characteristics at low normal stress and tend to transform from shear contraction to dilatation at higher stress, with pressure shear failure characteristics. In the near shear plane distributing the irregular rock clump, the shear appeares in the process of extrusion sliding and rolling shear failure surface grows concave and convex. With shear displacement increasing, the shear stress and strain energy  fluctuate and grow gentle. The peak shear stress obtained from the numerical calculation is higher than that of the insitu test. The calculated peak shear stress can be decreased effectively by reducing the particle radius.   References | Related Articles | Metrics

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Experimental Study of Mechanical Properties of Lime Stabilized Expansive Soil under the Condition of Eluviations FAN Yongfeng 2013, 47 (09):  1390-1394.  Abstract ( 810 )   Save In order to investigate the effect of eluviations on the mechanic performance of lime stabilized expansive soil, laboratory tests were conducted to reveal the influencing rules of lime proportion and age on the swellshrink properties of stabilized expansive soil. An optimal lime proportion was derived, a measuring device of eluviations was designed and the detailed test steps were given for reference. Besides, the variation law of the content of Ca2+ and the strength indexes with leaching days were discussed according to leaching tests. Based on the results of the laboratory tests, it is found that the cohesion force of the stabilized soils decreases with the decrease of the content of Ca2+, however, the internal friction angle remains constant. The influence of the decrease of the content of Ca2+ on the strength is disadvantageous to the long-term performance of subgrade.   References | Related Articles | Metrics

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Influence of Hardening Time and Concrete Grade on Rock Bolt Testing with Reflected Wave CHEN Jundong1,2,GE Xiurun1,LIU Jibin2,HE Faliang2 2013, 47 (09):  1395-1398.  Abstract ( 906 )   Save The physical model of rock bolt testing with reflected wave was analyzed and solution to the wave equation with damping coefficient was given. Besides, two analog experiments for different concrete grade and different hardening time were conducted. The experiments indicate that the hardening time has a greater influence while concrete grade has a minor influence on rock bolt testing.   References | Related Articles | Metrics

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Finite Element Method Regression Back Analysis of Initial Stress Field in a Large Underground Chamber Area WANG Yingyi1,LI Ke2,HUANG Xingchun1 2013, 47 (09):  1399-1403.  Abstract ( 914 )   Save Based on the measured initial stress, topography, geomorphology, and geological structure such as fault, a 3D FEM model was established for the multivariable regression back analysis of initial stress field in the underground powerhouse area of Changheba Hydropower Station. The results show that the FEM regression stress values are in good agreement with the measured values of the rock mass in the underground chamber area, and the regression method is effective for the back analysis; the horizontal stress is larger than the vertical stress, and the initial stress increases with the horizontal and vertical depth; and stress concentration appears near the fault, which should be paid attention for.   References | Related Articles | Metrics

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Analysis on Shear Strength Parameters Based on Drucker-Prager Yield Criteria LI Lei,ZHANG Mengxi 2013, 47 (09):  1404-1408.  Abstract ( 1150 )   Save The mathematical expressions of internal friction angle considering the influence of intermediate principal stress under true triaxial stress were deduced. After a comparison of the results of the true triaxial tests of gravel, Q2 loess and Santa Monica Beach sand, the relationships between internal friction angle and intermediate principal stress coefficient were studied based on DP yield criteria. The results show that the calculated values of internal friction angle with D-P yield criteria equal the testing results when the intermediate principal stress coefficient is suitable for the corresponding criterion. In order to obtain reasonable results, appropriate D-P yield criteria should be chosen for different materials.   References | Related Articles | Metrics

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Convex Corner Stability Analysis of Slurry Trench HAN Chang-yu, CHEN Jin-jian, WANG Jian-hua, XIA Xiao-he 2013, 47 (09):  1409-1412,1418.  doi: 10.16183/j.cnki.jsjtu.2013.09.015 Abstract ( 1020 )   HTML ( 295 )   PDF (737KB) ( 477 )   Save Three-dimensional limit analysis was utilized to determine the stability of the convex corner in a slurry-supported trench. Analytical solutions were derived for the safety factor of the convex corner stability in a slurry-supported trench. The failure surface has the shape of logarithm helicoids, with outline profile defined by a log-spiral curve. Power expressions were obtained for dissipation rate, gravity and slurry pressure. By solving the energy balance equation, the equation of safety factor for convex corner stability was obtained. The slurry weight ratio, the slurry surface depth, the angle of internal friction and other parameters were discussed. The result indicates that the stability factor increases with increasing slurry and soil bulk density ratio, cohesion, friction angle, but it decreases with decreasing slurry level depth and trench depth ratio, trench width and depth ratio. Figures and Tables | References | Related Articles | Metrics

Architechural Science

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Analysis of Deformation Properties of Subway Station Foundation Pit in Soft Soil with High Creep Property ZHOU Kunpeng1a,WANG Yingyi1b,ZHU Jiwen2,HUANG Xingchun1a,1b 2013, 47 (09):  1413-1418.  Abstract ( 854 )   Save In order to investigate the effect of soft soil with strong creep resistance on the deformation during construction, based on the foundation pit engineering of the South East Outer Ring Road Station in Ningbo, the deformation of the building envelope and the external surface subsidence were analyzed. The results show that the effect of the foundation excavation on the deformation of the building envelope and the external surface subsidence has an obvious time effect. So the time of deeper soil excavation should be strictly controlled  followed by timely erection of support and pouring of concrete floor. Meanwhile, the deformation and longterm displacement of the pit were calculated by combining the finite element modeling (FEM) with the displacement aging coefficient and taking the strong creep resistance into account. The numerical results conform to the monitored results, which verifies the feasibility of the method, and provides reference for similar excavation engineering.   References | Related Articles | Metrics

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Analysis of Displacement of Soft Soil and Its Application Considering the Rheological Property LAI Huahui1a,ZHU Jiwen2,WANG Yingyi1b,HUANG Xingchun1a,1b 2013, 47 (09):  1419-1423.  Abstract ( 886 )   Save Based on transient finite element method (FEM) and displacement aging coefficient, a method was  proposed to obtain the influence of the rheological properties of soft soil on engineering construction. The transient soil displacement was simulated using the FEM simulation method. According to analysis of soft soil from displacement timeliness, its transient displacement could be changed into long-time displacement with rheology. And the displacement aging coefficient was calculated from triaxial rheological test of soft soil and the most negative time in the site. So this coefficient can reflect the rheological unstable condition of soft soil. A case of excavation simulation of the South East Outer Ring Road Station in Ningbo was conducted using this method. The calculated displacement result of soft soil agrees well with the on-site monitoring result. References | Related Articles | Metrics

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Optimization Design and Application of Dewatering-recharge System in Deep Excavation YUAN Hua1，ZHANG Qinghe2 2013, 47 (09):  1424-1429.  Abstract ( 1064 )   Save A water level line equation under the coupling action of complete pumping-recharge confined well group was derived using the mirror image and superposition principle. Besides, based on the water level equation, an optimization design method for the deep foundation pit dewatering-recharge system was proposed, taking the allowable deformation of pit and surrounding environment as the main constraints. Taking the deep pit of a subway station as an example, the mathematical modeling and solving process for optimizing the number and assign position of pumping as well as the recharge well points were described. The results show that optimization design can not only ensure the safety of surrounding environment (nearby buildings etc.) and the normal operation of the dewatering project, but also reduce the project cost, which will be helpful for the same dewatering project. References | Related Articles | Metrics

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Effect Evaluation of Prestressed High-intensity Concrete Piles Applied to Ground Treatment of Dredger Fill WU Haoninga,LI Kea,HUANG Xingchuna,b 2013, 47 (09):  1430-1434.  Abstract ( 933 )   Save Based on the dredger fill foundation of a project in Hangzhou Bay, the subsidence features of the foundation were obtained through site tests. The finite element modeling (FEM) numerical simulation method was used to simulate the settlement of the dredger fill foundation. The effect of prestressed highintensity concrete (PHC) piles applied to ground treatment of the dredger fill was evaluated reasonably. Evaluation results show that PHC piles applied to ground treatment of dredger fill can obtain a significant  reinforcement effect. References | Related Articles | Metrics

Communication and Transportation

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Tunnel Supporting Theory and Method Based on Optimization of  Supporting Structure Strength and Deformation LI Ke1,WANG Yingyi2,HUANG Xingchun2 2013, 47 (09):  1435-1440.  Abstract ( 1008 )   Save The new Austrian tunneling method (NATM) is widely used in tunnel construction. Aimed at the deficiency of the secondary support time in NATM, the defect of classical ground pressure theory was analyzed, and a circular target optimization theory of tunnel support was proposed based on support control curve, engineering geology condition, and monitoring data. The support structure stress and surrounding rock deformation relation with different stress release rate were obtained by finite element method calculation. The target limited displacement was determined by considering support stress and surrounding rock deformation, and revised by the calculation of later excavation effect. The finial proper condition for secondary supporting was determined by considering the in-situ monitoring data. At last, this method was verified by engineering application.   References | Related Articles | Metrics

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Stiffness Effect Analysis on Support System of Beam and Slab Structure with Large Opening in Top-down Excavation Foundation Pit WANG Xin,ZHANG Qinghe,LAI Yunjin 2013, 47 (09):  1441-1446.  Abstract ( 902 )   Save The FEM method and theory of structure mechanics were adopted to analyze the relationship between the shape or the size of the opening and the support system stiffness of the beam and slab structure. The response of the lateral displacement and inner force of diaphragm wall with the variation of support stiffness in different depth were studied. The results show that the relation curves of the structure stiffness and opening size are different between the circular-shaped opening and square-shaped opening; however, the relation curves of the structure stiffness and opening area are similar between different opening shapes, and the opening area ratio can be used to determine the minimum structure stiffness and the maximum opening size of the beam and slab structure in engineering design. The lateral displacement of enclosure structure increases with the decrease of the support system stiffness, but no adverse impacts are noted to the inner force of the enclose structure. The inner force of the enclosure structure can be optimized by adjusting the opening size and shape of the beam and slab structure.   References | Related Articles | Metrics

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Elastoplastic Unified Solutions to Deep-buried Circular Tunnels Considering Intermediate Principal Stress YU Dongming1,FAN Yongfeng2，DUAN Jianxin1,LUO Xingwen1 2013, 47 (09):  1447-1453.  Abstract ( 861 )   Save Taking into consideration the influence of intermediate principal stress on deep-buried circular tunnels, and under plane strain hypothesis, the unified strength criterion was precisely matched to the Drucker-Prager strength criterion. The analytical expression of intermediate principal stress in plastic state for the perfect elastoplastic material with dilatancy was derived from the Drucker-Prager strength criterion. Combining the analytical expression of intermediate principal stress and non-associated flow rule, unified solutions for stress and strain of the tunnel plastic area were obtained. The result shows that the classic solutions of Kastner are special cases of the unified solutions. A practical engineering instance was given according to the unified solutions and the regularities which intermediate and dilation angle act on the surrounding rock of the deepburied circular tunnel plastic area were discussed.   References | Related Articles | Metrics

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Field Test of Segment Characteristics for Shield Advancing in Mined Tunnel ZHANG Changguang1，ZHANG Qinghe2，ZHANG Zhenguang3 2013, 47 (09):  1454-1458.  Abstract ( 973 )   Save In the construction of a certain tunnel in Shenzhen Metro, a field test of segment characteristics was conducted for the novel shield after the drill and blast composite construction method. The concrete strain gauge, earth pressure cell and reinforced axial dynamometer were installed. The variation laws for the longitudinal strain of girth contact surface for concrete segment, earth pressure and axial force of reinforced instrument were monitored and discussed. The results show that the variation with time of monitoring values can be divided into two stages; the overall prepressure basically meets the requirement; the longitudinal strain of girth contact surface for concrete segment and earth pressure are very unevenly distributed; grouting can improve and control the force and floating of segment; reinforcement design of segment should be optimized as the measured axial force is much smaller than its design value; a number of orderly tightening ring bolts and grouting behind wall segment are needed. Key words： References | Related Articles | Metrics

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Numerical Analysis of Embankment Reinforced with H-V Reinforcement under Traffic Loading   WANG Yiming,ZHANG Mengxi,QIU Chengchun,LI Lin 2013, 47 (09):  1459-1463.  Abstract ( 813 )   Save In order to study the embankment reinforced with Horizontal-Vertical (H-V) reinforcement under traffic loading,  a two-dimensional model was calculated by finite element method (FEM) program ABAQUS using dynamic explicit. According to the result of dynamic triaxial tests, fitting strainsoftening curve was written into user subroutine in ABAQUS. The deformation and strain of the embankment without reinforcement, with ordinary reinforcement and with H-V reinforcement were analyzed and compared. The H-V reinforcement significantly reduced the strain, vertical displacement and horizontal displacement and controlled differential settlement in embankment under traffic loading. H-V reinforcement had a better reinforced effect than ordinary reinforcement, especially in the control of horizontal displacement. References | Related Articles | Metrics

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Coupled Dynamic Response of Subway Train and Intercity Train XIAO Li1，ZHANG Qinghe2 2013, 47 (09):  1464-1468.  Abstract ( 918 )   Save Based on Jinbin mass transit under-crossing intercity rail, the multi-vibration calculating model of finite element and infinite element was created based on the ABAQUS/Explicit module, and train loads were imported by the multi-point input method. Besides, the dynamic response of the surrounding environment under the condition of high-speed train in different speed, single subway train vibration, two subway train coupling vibration etc. were calculated, and the acceleration and displacement in different conditions were analyzed. References | Related Articles | Metrics

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Calculation Model of Shield Tunneling Stability Based on Real Face Failure Modes HU Xinyu1,ZHANG Zixin2 2013, 47 (09):  1469-1476.  Abstract ( 794 )   Save The assumption of excavation failure mode is based on the traditional wedge model which is not suited to usual clay soil and sandyclay layered soil. This paper presents a novel wedge model for the analysis of face stability, taking into consideration the real failure modes, the character difference of layered soil and the arching effect of soils. This model is an extension of the widely-used Terzaghi’s pressure equation. The results show that the critical supporting pressure, greatly affected by the overburden soil pressure, increases sharply with the increase of embded tunnel depth. The critical supporting pressure could be determined accurately by the suggested novel wedge model. The value of supporting pressure is closely related to the openangle α and dip angle  θ of the wedge itself and is unique when α=90°－θ. The rationality and feasibility of the novel wedge model and the determining method for critical supporting pressure were verified by a field case and the results could provide a reasonable reference for similar engineering conditions. References | Related Articles | Metrics

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Influence of Cushion Roughness on Grouting Treatment of Immersed Tunnel   XU Jie 2013, 47 (09):  1477-1481.  Abstract ( 929 )   Save Changes of cushion roughness caused by scraping-paving and change of particle size will affect slurry diffusion, grouting volume and grouting pressure, when adopting grouting method in foundation treatment of immersed tunnel. Model test was conducted to analyze slurry diffusion, grouting volume and grouting pressure during single-hole grouting and dual-hole grouting, adopting 2mm, 5mm and 10mm diameter particles for cushion. It was indicated that the velocity of slurry diffusion and grouting volume increased with the increase of cushion particle size. The range of grouting pressure fluctuation would be larger when adopting larger particle size cushion, the grouting pump would be difficult to control and the slurry diffusion would turn to one direction. Based on the test result, the slurry diffusion velocity, grouting volume and grouting pressure ought to be considered comprehensively when choosing cushion particle size.   References | Related Articles | Metrics

Automation Technique, Computer Technology

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Feature Extraction and Corresponding Processing of Rock Surface Image   YU Chunping1a,GUO Qiang1b,LIAO Zhengbiao2,LIANG Zhiwei3 2013, 47 (09):  1482-1486.  Abstract ( 1005 )   Save Basing on the comparison of several methods, this paper proposed systematic steps in extraction the features of rock surface image including image enhancement， binarization, edge extracting, Hough trasformation,etc. Besides, it proposed 3 restrictive conditions to reject the redundant line segments and gave the corresponding processing flow. In addition, it developed the software to test the feasibility of the method simultaneously. The result showed that the repetition rate of the line segments reduced significantly, which could indicate the distribution of the joints more precisely.   References | Related Articles | Metrics