bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Optimization of Reinforced Concrete Aqueduct with Multi-Longitudinal Beams Part II: Application
Authors: Guan Jun Feng , Li Xiao Ke , Zhao Shun Bo
Published: May 2011

Based on a 3-D solid finite element parametric model, an optimization design method of reinforced concrete aqueduct with multi-longitudinal beams is proposed. In this method, the stress of sidewall and subplate is controlled by the sectional crack-resisting criteria, the space between longitudinal beams or crossbeams is decided by the coordination of structural deformation, and the bottom stress of longitudinal beams or crossbeams is restrained by the nominal tensile stress. Taking the lightest dead weight of aqueduct as the objective of optimization, this method is able to give the optimal sizes and distribution patterns of the main load bearing members. The internal force of each structural element of the optimized aqueduct is calculated by a 3-D beam-shell finite element numerical model and thus the reinforcements are arranged. Compared with the prototype, the optimized aqueduct shows the advantages of lighter weight, more reasonable stiffness distribution, coordinated deformation and economical reinforcements.
Experimental Study on Bearing Behavior of Large-Diameter Overlength Squeezed Branch Pile
Authors: Jia Jin Lu , Wang Zhong Fu , Zheng Jian Hua
Published: May 2011

Squeezed branch pile is based on the traditional uniform pile in development of a new type of pile, with a high bearing capacity, settlement of small features widely used in the engineering. Based on the actual project site static test, analyzed the vertical bearing capacity characteristics of two adjacent squeezed branch piles; By means of testing of the pile stress gauge steel embedded in different parts of piles, the axial force transfer characteristics of the body, support plate side resistance drag and play characteristics of the squeezed branch pile were analyzed. The results showed that: the branch pile Q-S curve is slowly varying type, the three branch share of the load ratio increases with the pile top load increases and then decreases, load sharing ratio of 12% or so. The side resistance increased with the pile top displacement, the curve showed significant enhancement traits. Measured friction value of two test piles is too conservative under the existing norms, the actual measured value of 1.2～1.6 times of the standardized value.
Experimental Study on Bearing Behavior of Large-Diameter Overlength Cast-in-Place Bored Pile Post-Grouting
Authors: Jia Jin Lu , Zhou Min , Zheng Jian Hua
Published: May 2011

The bearing capacity property of large-diameter bored cast-in-situ deep and post-grouting pile is analyzed on the basis of measuring data of static load test and axial stress measure data. The study indicates that the large-diameter bored cast-in-situ deep and post-grouting pile show the characteristics of the friction when the bearing course at pile end is sand, when the pile top load is greater than 18000kN, the pile end begin to resistance and the share proportion is small, only 1% to 10%; the load settlement cure is gradual decline, no inflection point, the settlement of pile compression only accounted for about 15%, The developing degree of side resistance is well corresponding to the relative displacement between pile and soil. The side resistances significantly enhance effect, the measured value of the soil side resistance is 1.3 to 1.5 times of survey report recommended.
Laboratory Evaluation of the Stress-Strain relationship of Permeable Concrete
Authors: Hussin Manal , Yan Zhu Ge , Bullen Frank , Lokuge Weena
Published: May 2011

The authors conducted research aimed at developing a new type of permeable concrete material with enhanced structural strength. This paper presents and discusses the results of their investigation on the unaxial compressive stress-strain relationship of porous concrete made with two different mix designs with constant water to cement ratio. The concrete mixes were designed with a target compressive strength between 15-25 MPa and target porosity between 10-15% to study the effect of pore sizes on the stress-strain curve. The average pore space was increased by increasing the relative amount of large aggregate. The reduction in the relative amount of fine aggregate increased the average pore space and resulted in a reduction in mix stiffness and a marginal increase in ultimate strength.
Research on Intelligence Analysis System for Karst Water Inrush Geological Risk Assessment during Tunnel Construction
Authors: Xie Jin Shui , Bai Ming Zhou , Yang Yin Jing , Xu Zhao Yi , Zhang Ai Jun , Wang Peng Cheng
Published: May 2011

With Yichang-Wanzhou Railway project being taken into account, this article systematically analyzes the control factors of geological hazard in tunnel construction including stratum, lithology, fold, rupture and groundwater seepage,etc, establishes hazard assessment index system, and induces the underlying principle and methods of index assignment. On the basis of the theory and technology of expert system, this article develops an intelligence analysis system for karst water inrush geological hazard risk assessment in tunnel construction, explores the construction method of karst water inrush geological hazard expert system and the implementation of software platform, and takes Qiyueshan Tunnel as an example to make the research of engineering application.
Effect of Perma-Zyme on Properties of Tabia Used to Protect Ancient Earthen Ruins
Authors: Peng Hong Tao , Zhang Qi , Li Nai Sheng , Wang De Fa
Published: May 2011

Perma-Zyme is an enzymatic stabilizer. To test the feasibility of adding Perma-Zyme to tabia used to protect ancient earthen ruins, the 28d unconfined compression strength, permeability and color-difference were tested to determine the difference between the tabia and tabia treated with Perma-Zyme. The experimental results show that the 28d unconfined compression strengths of specimens treated with Perma-Zyme are higher than those without Perma-Zyme, and the color-difference(DE*) between the tabia and tabia mixed Perma-zyme is larger than 3(suggested color tolerance Chinese standardized GB/T 15608-2006), and the permeability coefficient of tabia mixed Perma-Zyme is smaller than that without Perma-Zyme, i.e., has better impermeability. Box dimension values of SEM images(with different scale bars) of samples were computed by box-counting method. Box dimension values of SEM images of the same sample are different on different scale bars. The analysis shows that SEM microstructure of the tabia sample treated with Perma-Zyme is finer and denser than the one without Perma-Zyme.
The Active Mechanism of Xi’ an Ground Fissures and Discussion on a New Material for the Ground Fissure Disaster Prevention
Authors: Li Xin Sheng , Meng Fan Yu , Liu Chao , Meng Hua Jun , Zhang Peng , Wan Tong , Shang Jin Yu , Cao Wei Zhong , Lan Yang
Published: May 2011

The genesis of Xi’ an ground fissures and the recent activity characteristics and tendency have been introduced firstly. The architectural damage caused by ground fissures and current hazard prevention methods have been described secondly. The applications of a new material used in controlling underground engineering and coal mine disaster have been introduced. The mechanical properties of the new material have been stated also. As a result, a new foundation treatment method has been envisaged to make it possible to construct architectures on ground fissures.
Study on the Landslide Stability Influenced by the Reservoir Water Lifting and Atmospheric Rainfall
Authors: Hu Gao She , Ding Yan , Liu Jun
Published: May 2011

This article is based on the Bazimen Landslide in the three gorges reservoir area to be the object of study, and uses the Boussinesq unsteady aeolian-equation to calculate the change of the infiltration line in the landslide by the reservoir water decreased and rainfall. The limited equilibrium method is taken to study the variation law of the landslide stability, which is effected by the every factor under different working conditions.
A Study on Forming Mechanism of Gas Tunnel in Non-Coal Strata
Authors: Kang Xiao Bing
Published: May 2011

In addition to the gas tunnel in coal strata, there are a large number of gas tunnel in non-coal strata, these tunnels itself do not through the coal strata, but all encountered the gas problem in the construction process. Because of not a full understanding and preparation on gas of tunnel in non-coal strata zones, and the gas emission is random, uneven distribution of the characteristics, so the gas disaster hazard is larger in such gas tunnel, study on its formation mechanism is great significance. Based on the study of a lot of the gas tunnel has been constructed, summed up three genetic types of the non-coal strata gas tunnel: one type is structural connectivity, according to the different structure types, can be divided into fracture connectivity type, fault type and fold connected connectivity type; Second is surrounding rock metamorphic type; third is compound effects type.
Study on the Mechanism of Water-Rock Interaction of the Black Rock Strata
Authors: Liao Xin , Wu Xi Yong , Duan Jiang Tao
Published: May 2011

Black rock strata with special engineering geological characteristics are distributed widely in different geological periods and areas. The scattered sulfide minerals in the rock strata are changed in a short time under the action of the oxygen-rich surface water and oxygen-rich groundwater. And the acidic water with strong erosiveness is formed. Then water--rock interaction between other minerals and the acidic water subsequently occurs with a series of chemical reactions. It can affect the stability of the black rocks themselves and other non-black rocks nearby directly, and cause engineering and environmental geological problems. Through the combination of engineering project and immersion test indoor, the mechanism of water-rock interaction of the black rock strata is researched. Engineering preventions and measures in the black strata region are proposed to avoid the damage to project and the ecological environment around.
A Study on the Groundwater Tracer Test in the Dragonmount Tailing Pond, Guangxi Province
Authors: Li Yuan , Qi Jian Feng , Jia Lei , Zhang Ying
Published: May 2011

The dragonmount tailing pond which is taken as the study area has complex hydrogeological condition. It lies in Jingxi county, Guangxi province. In this paper, it gives out the time-concentration curve for the groundwater tracer test, makes use of single-dimensional hydrodynamic dispersion model to figures out the velocity of groundwater, coefficient of dispersion and dispersity. The mechanism of multimodal and double-humped phenomena was also investigated in the tracer test. In this paper, some situations such as leakage path, the trend of groundwater, hydraulic connection were analyzed. The research provides necessary hydrogeological basis for the design of the tailing pond and it’s of great significance to evaluate the pollution of its water source and conduct the construction.
Control of Water and Sand Gush in Tunnelling with Earth Pressure Balanced Compound Type Shield
Authors: Lei Jin Shan , Yan Li Ping , Yang Xiu Zhu , Liu De Zhi
Published: May 2011

The sixth line of Guangzhou Metro Subway is partially located in silty fine sand layer, which is incompact, rich in water, and has high permeability and low bearing capability. When tunnelling in this section, it is easy to bring about gush of water and sand, which will cause the ground surface to settle. Therefore, a two-staged helical conveyer was used to control this phenomenon during tunnelling. First, both the dregs outlets of helical conveyer are turned off to prevent water and sand from rushing forth, then foam material is injected into the earth cabin and the front-end of helical conveyer to keep the cabin pressure from decreasing. Secondly, drain outlet of the second helical conveyer is turned on and the water is drained, then dregs outlet of the second helical conveyer is turned on to discharge the dregs. Finally, dregs outlet of the first helical conveyer is turned on to discharge the dregs in the earth cabin. Such technique was used successfully in tunnelling the section from Datansha to Ruyifang of the sixth line of Guangzhou Metro Subway. It ensured that sinking of the ground surface was avoided while the tunnel shield went through the silty fine sand layer that is rich in water.
Compression Test of Lining of Tunnel Fireproof Concretes
Authors: Yao Rong , Peng Dong Ling , Huang Hong Yuan
Published: May 2011

The polypropylene, the silica flour and the carbon fiber will be considered to be added into the concrete when test, the orthogonal theory is used in this test, 32 groups samples were made, the heater was put for heating by choosing the RABT curve, the test result was analyzed, the ratio of compressive strength loss is changed with the meter of the polypropylene textile fiber, the silica flour and the carbon fiber, there is a optimality Proportion when the ratio of compressive strength loss is low.
Loess Highway Tunnel Supports Stress Analysis and Construction Method Mechanism
Authors: Liu Chang Jiang , Li Fang Ming
Published: May 2011

In view of the easy collapse characteristic of loess highway tunnel, as well as the theory upon the reality of practical engineering. Northwestern Region Qingshui County domestic Li Jiaping loess highway tunnel construction is taken in this article. And the new questions of practical research is proposed. The technical questions during the construction of shallow loess highway tunnel, the construction plan, the distribution rule of contact stress between the support and soil, and the distortion reason of structures are all analyzed. The loess highway tunnel stability calculation and analysis is consummated. Thus the theory basis of the possible to supply the reference for this kind of project's practical application is provided.
Development and Application of Complementary Support Technology under the Condition of Weak and Broken Surrounding Rocks
Authors: Wang Hong Wei , Jiang Yao Dong , Zhu Jie , Zeng Xian Tao , Jiang Peng Fei , Zhang Xiao Tian
Published: May 2011

The support of surrounding rock under the condition of deep mining has significant challenges due to high stress and low rock strength environment. Using the method of strengthening broken rock, reinforcing support force and releasing the mine-induced stress, this study has pointed out the complementary support technology which is based on the support using bolt-wire-shotcrete and is combined with steel arched yielding support. For the purpose of permanent support, the complementary support technology could combine the each support element and adequately take advantage of load-caring capacity of surrounding rock. The monitoring data of Xiaokang coal mine, Muchengjian coal mine and Yangquhe coal mine indicate that, for the various geological conditions, complementary support system has provided powerful support force to resist large deformation of weak and broken surrounding rock. It is proved that this type of support technology could reduce the mine-induced stress as well and has economical significance.
Research of Mechanical Design of Corner Joints in Gabled Frames
Authors: Wang Yu , Xu Guo Meng , Liu Yong Jun
Published: May 2011

In order to clear mechanical design of corner joints, it is necessary to further investigate mechanical property of corner joint in gabled frames. Through relevant requirements of the existing cause and ANSYS finite element software analysis, contrasting. Some conclusions are given in the article. The analysis results show that setting stiffener in the line of inside and outside corner folded point is necessary and simple. Meanwhile, the calculation formula is given.
Risk Control in the Deep Excavations with the Application of the Observational Method
Authors: Ma Jian Qin
Published: May 2011

The uncertainty of the ground, in which a deep excavation to be conducted, is always inherent. The risk control of the excavation is therefore necessary. Based on the principle features of a deep excavation, a general process of risk control is presented in terms of design and construction, with the application of the observational method. To avoid the conflicts of the involved groups’ interests, a close co-operation between the groups in a well planned procedure is vital to the success of the risk control, especially to the case with rapid deterioration stages included.
Study on Underground Utilities Settlement during the Construction of Shield Tunnel
Authors: Sun Hai Xia , Wu Hai Yu , Zhao Wen
Published: May 2011

Shield tunneling construction inevitably makes impacts on underground utilities. This paper takes some Metro engineering for background, study the underground utilities settlement rules induced by shield tunneling construction. As for shallow-buried and high ground water table tunnel, the coupling of hydrological and stress field must be paid attention. By seepage continuity equation and hydrodynamic equations, study changing situation of the deformation and stress by contrast the effect of seepage. And, contrast the measured value and simulation value to verify the rationality of using fluid-solid coupling method to forecast the ground settlement during tunnel construction.
The Method of Optimizing Blasting Parameters for Driving Tunnel Based on the Outcome Analyses
Authors: Dai Jun , Liu Yuan
Published: May 2011

To get optimum blasting parameter bringing out the best blasting outcome is very helpful to increase the speed and efficiency in tunnel-building. For this reason, the effect of blasting parameters on blasting outcome is analyzed based on that the rocks are complex and changeful through which the tunnel is driven and that there is a gap between blasting theory and blasting practice. The method helpful to get the optimum blasting parameters is present in which the blasting outcome is measured, recorded and analyzed, and the blasting parameters are adjusted aiming at the specific tunnel according to the blasting theory and the blasting technician’s experience. The presented method is important and significant for improving the tunnel-building technique by blasting, realizing the high speed and efficiency of tunnel-building by blasting.
Analytical Approach for Face Stability Estimate of Tunnel with Pipe Roof Reinforcement
Authors: Song Hong Wei , Wang Hai Tao
Published: May 2011

One of the most popular pre-reinforcement structures in the construction of tunnels through weak grounds would be the pipe roof reinforcement. This composite structure consists on installing, prior to the excavation of a length of tunnel, a series of pipes, either parallel to the tunnel axis or at a certain angle with it. By injecting grout through the pipes, the ground in between the pipes is stiffened and the pipes are connected, creating a kind of ‘umbrella’ above the area to be excavated. In this paper, by modifying the upper bound solution for tunnel face stability, the three-dimensional model for expressing the tunnel face stability with pipe roof reinforcement was established. For a typical example, the solutions computed by the proposed approach were compared with the results given by wedge model, trapezoid wedge model and centrifugal-model test to verify the reasonability of the method. It is shown that the calculation results of limit analysis are in close agreement with test results.
Coupling Analysis of Seepage and Stress in Jointed Rock Mass of Equivalent Continuum
Authors: Xiao Tao Li , Li Xin Ping , Dai Yi Fei
Published: May 2011

Under the action of stress and crack hydraulic pressure, the damage and rupture of jointed rock mass accumulate and extend simultaneously during the process of its crack occurrence and growth. The rock mass’s damage will be accumulated owing to its rupture, and the damage is closely related to the rupture. Taking into account comprehensive the stress intensity factors both of plane stress and plane strain for hydrous jointed rock mass, two new equations of crack propagation and the new crack length were built on the basis of energy criterion. Assuming the jointed rock mass as equivalent continuous mass with damage and introducing the damage constitutive equation of rock, the damage evolution of the hydrous jointed rock mass is simulated by the damage tensor and the damage strain. The model is used to simulate one tunnel. Through simulation, the waterhead contour is more smooth when the coupling is considered than is not considered, and the maximal displacement almost the same because the diversion tunnel was bulit.The simulate results can provide a reasonable recommendation to the engineering practices.
Analysis of Seismic Response of Water-Conveyance Tunnel with Shaft
Authors: Liu Jin Yun , Chen Jian Yun , Su Zhi Bin , Xu Wei
Published: May 2011

The shaft is accessory structure of water-conveyance tunnel, so study on law of seismic response of water-conveyance with shaft is very necessary. This supply reliable criterion and reference for structural design of water-conveyance, and haves important significance.
Study on Risk Acceptance Criteria of Tunnel Engineering under Construction
Authors: Wen Sen , Zhao Li Min , Yuan Yu Qing
Published: May 2011

Many tunnels are going to be driven in China. In order to reduce accidents, the effective measure is to carry out risk evaluation in advance. So it is necessary to study risk acceptance criteria for providing standard of risk evaluation. Individual risk and social risk acceptance criteria are mainly studied in this paper. Individual risk can be derived by the product of former average individual risk level and influence coefficient of national laws. The shape of FN-curve is determined by the combination of neutral and conservative utility theory. Parameters in the curve equations can be calculated by investigating former risk data and known conditions.
The Slabbing Mechanics Analysis of the Tunnel Lining
Authors: Wu Zu Song , Chen Guang Qi , Zen Kou Ki , Liu Xin Rong
Published: May 2011

When the road tunnel is excavated, the multi lining is used to being applied. In order to keep the surrounding rock stabilize and arouse the self-stability of the surrounding rock, building the first support is essential. But the slabbing often occurs near the spring line on the surface of the first lining, and because the slabbling is a common failing and not attracted our most attentions, it will develop to the crack and threaten the stability of the structure finally. This paper uses the line elastic method to analyze the mechanics that causes this slabbing phenomenon via the interaction between the surrounding rock and the first lining, and suggests the measure that escape the slabbing.
Experimental Study and Numerical Simulation of Rock Mass Seepage Characteristics of Tunnel Engineering
Authors: Jiang Yong Dong , Xiong Ling , Yang Xing Yang , Zhen Quan , Yan Zong Ling
Published: May 2011

In this research, the MTS815 rock mechanics test system , produced by American MTS co., has been conducted with transient method to study the seepage characteristics of rock under different confining pressure. Experiments have obtained the following results: with the confining pressure increased, penetration ability of water in rock decreased, but the start-up pressure gradient increased; permeability of rock decreased with the increase of effective confining pressure, which had negative exponent functional relationship between them. Based on previous researches, the study has established filtration equation which couples with stress field, temperature field and seepage field. Combined with the practical tunnel project, numerical simulated the variation characteristics of deformation of tunnel surrounding rock, pore pressure and seepage field under three fields non-coupling and coupling, numerical simulation obtained: the difference among deformation of surrounding rock, pore pressure and seepage field distribution under the coupling and non-coupling is remarkable, so it must consider the simultaneous action of fluid - solid - heat when we need to research the working of seepage law of groundwater in tunnel rock mass, and the research results enjoy important theoretical significance and practical application value.
Research on the Blasting Shock Absorption Technology of Shallow-Buried Tunnel Under-Traversing the Dense Houses
Authors: Huang Ming Li , Meng Xiao Wei , Tan Zhong Sheng
Published: May 2011

How to deal with a conflict between blasting vibration damage of tunnels construction with complex shallow and the efficiency has been always a difficult technical problem. Relying on the Chang Hong Ling tunnel which under-traverses the Jiangchi Town, using of field monitoring method to comparative study on the blasting vibration under different blasting scheme construction, research shows that: the up-step of non-blasting excavation + lower-bench of controlled blasting technique, successfully controls the surface blasting vibration speed within 1.5 cm/s.Then the tunnel can be constructed safely and rapidly, which provides a reference for the blasting excavation engineering in urban.
Research on Pre-Reinforcing Composite Foundation with a Shield Tunnel Under-Passing
Authors: Peng Zhi Yong , Liu Wei Ning , Zeng Qiao Ling
Published: May 2011

This paper analyzes the per-reinforcing effects of composite foundation with a shield tunnel under-passing, and tries to find the regularity in soil foundation improvement under such conditions. The paper establishes piles-soil separation model using software FLAC3D in a finite difference method and research the influence of effective pile length and effective replacement rate on ground deformation under the condition of shield-driver tunnel excavation. there does exist the optimum reinforcement range about pile length and replacement rate between the surface and the top of tunnel. Moreover this can offer reference for similar projects to a certain extent.
Model Test on Structural Behaviour of Underwater Shield Tunnel with Large Cross-Section Considering Assembling Modes
Authors: Zhou Ji Min , He Chuan , Feng Kun , Xiao Ming Qing
Published: May 2011

Taking Nanjing Yangtze River Shield Tunnel with large cross-section (Φ14.5m) as background, the mechanical characteristic of lining structure under high hydrostatic water pressure for different segmental assembling modes is studied by large-scale similar model test. The test system can control earth pressure, uniform and non-uniform water pressure acting on lining respectively and cooperatively. The study results show that the values and distribution of deformation and internal force vary with different assembling modes. The rigidity of the whole ring for straight joint assembling is less, inducing the deformation larger and internal force smaller, which is unfavorable for waterproofing requirements. The peak positions of bending moment change with the difference of staggered joint assembling modes. Due to the smaller rigidity of K segment, the value of bending moment on that position is less. The most favorable and unfavorable assembling modes are proposed for construction design for Nanjing Yangtze River Shield Tunnel; meanwhile it can also provide important reference to the correlative project.
Control Parameters of EPB Shield Tunneling in Weathered Granite Ground and Below Existing Tunnels
Authors: Li Xing Gao , Yuan Da Jun , Hu Hao
Published: May 2011

The choice of reasonable parameters of EPB shield tunneling in weathered granite ground is of great importance to reduce tunneling-induced effects on existing tunnels. Combined with the practice of the EPB shield tunneling below existing interval tunnels from Kexueguan station to Dajuyuan station of Shenzhen metro line No.1, the method of design and regulation of main parameters including the earth pressure in excavation chamber, the ground conditioning, the volume of the discharged soil, the grouting control and the advance speed, of the EPB shield tunneling are studied. The practice of the below-crossing shows in the weathered granite ground, it is reasonable that the earth pressure in excavation chamber is taken as 0.15-0.2 mpa, and that FER, FIR and CF of foam are taken as 8-15, 30-50% and 3-5% respectively, and that the amount of synchronization grouting is 8-10 m3 per ring along with the injecting pressure of 0.3-0.4 mpa, and that the second phase injection is employed to control the further settlement of existing tunnels when necessary, and that the advance speed is taken as 8-10 mm/min, and as steady as possible. Meanwhile, adjustments according measured data must be performed when necessary. Moreover, the real-time monitoring and a collaborative-work environment among the Parties involved in project are also very crucial to facilitate the risk management of the below-crossing.
Fundamental Research on Drilling Processes Using Drag Bits
Authors: Li Zhan Tao , Itakura Ken Ichi
Published: May 2011

This paper proposes an analytical model to describe rock drilling processes using drag bits and rotary drills, and to induce relations among rock properties, bit shapes, and drilling parameters (rotary speed, thrust, torque, and stroke). In this model, a drilling process is divided into successive cycles. Each cycle includes two motions: feed and cutting. According to this model, drilling torque includes four components generated from cutting, friction, feed, and idle running respectively, the first three items are all proportional to the uniaxial compressive strength (UCS) when the penetration rate is constant. Laboratory tests verified the correctness and effectiveness of the proposed model qualitatively. Especially, the influence of friction on the flank face and the idle running was confirmed. Field experiments were performed. The results showed good correlation between the torque, penetration rate, and UCS. The proposed model and equations engender the possibility of eliminating useless components of cutting forces when investigating the relation between mechanical data and physical properties of rocks.
Mechanical Analysis on Secondary Lining Damaged by Local Load under Earthquake
Authors: Yu Yuan Yuan , Guo Xun , Wang Ning Wei , Liu Hong Biao
Published: May 2011

Secondary lining of Longxi mountain tunnel damaged seriously during Wenchuan earthquake. To interpret the seismic failure reasons about secondary lining, the analysis adopts mechanical calculation and numerical simulation method. As a result, it was found that the bearing condition of secondary lining has an obvious spatial effect when the local loads act on the tunnel. Due to the inertial force of local load exerted by vertical seismic action, the secondary lining tends to be cracking, spalling, or even collapse.
Numerical Analysis and Optimization of Wedge Box of Diagonal Brace
Authors: Li Wei
Published: May 2011

Force transmission triangular box as the bracing’s bracket is widely applied in the deep foundation, but its performance was not studied in depth. In order to evaluate the working performance of force transmission triangular box as bracing’s bracket, the paper use the finite element software ANSYS to simulate and analyze its mechanical behavior. The bearing capacity, deformation and stress distribution of the components were discussed and compared with the result from elastic bending theory of small deflections of its end-plate deflection. The dangerous sections of member and the inner force distribution in the general work load status were obtained. And the stress concentration was improved. the results can provide reference for the design and construction.
Research on the Solutions to the Concrete Durability of Newly-Built Tunnel Structure
Authors: Wang Hai Yan , Qiu Wen Ge , Chen Xue Feng , Gu Hao
Published: May 2011

Through the survey about the durability of existing railway and road tunnels, it is found that there are different kinds of defects in most tunnels concerning poor durability. This phenomenon exists for a number of reasons among which the main ones are geological conditions , hydrological conditions, types of concrete structures, poor grading, larger second lining thickness, excessive larger stiffness and the poor quality construction. Solutions of these problems are provided in this paper. Specific measures are using multiple composite cementitious materials (the cocktailtreatment), providing composite cementitious materials with mixing station mode, using effective superplasticizer with low water-cement ratio and small water usage, adding appropriate amount of cellulose fibers in concrete, emphasizing the initial support and belittling the secondary lining, using reasonable maintaining technology, using new technology of Waterproof Plate. These measures may serve as reference for tunnels’ design and construction.
Three Dimensional Numerical Simulation Study on Lining Pressure of High-Speed Railway Tunnel
Authors: Ma Yun Dong , Li Bo , Fan Bin
Published: May 2011

The aerodynamic numerical simulation model of high-speed railway tunnel was established based on the analyzing of the aerodynamic effect characteristics of high-speed railway tunnel. FLUENT three dimensional compressible flows SIMPLE algorithm was adopted, the three dimensional aerodynamic effect of high-speed railway tunnel was simulated on the condition that the high-speed train was in motion. The pressure changes law in the tunnel was obtained during the whole process when high-speed train traveling, and the pressure-time curve in the tunnel middle cross-section was plotted. It laid a foundation for the further development of tunnel lining dynamics analysis.
Relation of Textural Stress and Rock Failure of Diversion Tunnel
Authors: Gao Rui
Published: May 2011

The textural stress has great effect on the stability of rock. According to the measured geo-stress data, through FEM and combined with the linear multivariate regression method, the geo-stress field was conducted. Using these methods, a diversion tunnel of a large-scale hydropower station was analyzed to study the stress distribution. It was shown that the stress concentration was located at the bottom of the wall and the arch top, the stress in the wall was little and the failure happened at the bottom of the wall and the arch top, then the bottom board and some areas far from the tunnel. Under the condition without considering textural stress, the stress concentration area located in the wall and the failure happened at the bottom of the wall, then in the middle of the wall and at the arch top.
A Prediction Study of Water-Gush Yield in Long Tunnels
Authors: Pan Hai Ze , Cao Jiang Ying , Huang Yuan Chun
Published: May 2011

The thought and method are put forward to deal with the difficulties in prediction of water-gush yield in long tunnels. The conceptual model of hydrogeology should be developed first based on investigating and analyzing the hydrogeology conditions of tunnel. Then, several different models should be adopted together to comprehensive calculate water-gush yield. Finally, by adopting methods of numerical simulating method, rainfall infiltration method and fuzzy comprehensive evaluation method, the comprehensive prediction thought presented above is applied and verified in Nanliang tunnel engineering practice.
Model Test and Numerical Simulation for Support Time of Tunnel in Loess
Authors: Ye Chao Liang , Zhu Yong Quan , He Ben Guo
Published: May 2011

The work presented in this paper focuses on support time for tunnel, which has much effect on stability of tunnel. Based on loess tunnel of Zhengzhou-Xi’an high-speed passenger rail line in China, large scale model test with geometric proportion 1: 20 was applied to study on different support time. Supplemental numerical analysis was carried out to investigate the effect of release ratio of stress which cannot be covered by model test. It is revealed that it is asynchronous change for deformation, strain and stress of surround rock. If the supporting constructs prematurely, internal force of support would be excessive greatly and if the supporting constructs too late, it will bring excessive slack pressure which leads to the plastic zone unfavorable, even tunnel collapse. The reasonable support time can improve self-bearing capability of surrounding rock and reduce the cost. The limited displacements about 17.8 cm for crown and 12.9 for horizontal convergence are gained. The research results can act as reference for similar materials tunnel and underground engineering construction.
Nonlinear Performance Simulation of RC Structures with Small-Scaled Model in Earthquake Simulation Test
Authors: Meng Qing Li , Zhang Min Zheng
Published: May 2011

For small-scale RC structure model in earthquake simulation test, the material behavior of the model is hard to resemble the prototype well so that the model cannot simulate correctly the nonlinear performance of the prototype. On the basis of the dynamic similitude of mechanical behavior between common concrete and micro-concrete which derive from mechanical behavior tests, the simplified equivalent dynamic similitude relations, which are applicable to the nonlinear performance simulation with small-scale RC structure models in the earthquake simulation tests, have been proposed. By the numerical simulation of earthquake simulation tests and the deviation analysis, the dynamic simulation experimental method has been verified. In addition, for small-scaled RC model, to consider the similitude harmony between concrete and reinforcement used in the model, by adjusting the reinforcement and stirrup, or the effective section height (h0) and hoop spacing etc., simple element testing, shaking table test and numerical simulation were carried out to verify this model design method. Thus, it’s realizable that the small-scaled RC model can simulate correctly the nonlinear performance of the prototype.
Experimental Study on Seismic Performance of New Type of RC Core Walls
Authors: Huang Xuan Ming , Zhang Jing
Published: May 2011

In high-rise concrete structures, the elevator or stairs which located in the middle of the building are always put into the RC core walls. It not only meets the requirements of the function of usage, but also makes the core walls bear most of the lateral force and becomes the main component in the whole structure that resists the lateral force. Therefore, the seismic performance of RC core walls is of great concern to engineering. At present, there is little experimental study on measures of improving the seismic performance of RC core walls. In this paper, firstly, a new type of construction measure is put forward to improve its seismic performance. Secondly, through the experimental study on one 1/6 scale core walls with concealed bracings and one 1/6 scale normal core walls under the low cyclic loading, the effect of concealed bracings on bearing capacity, stiffness, ductility, hysteresis, failure phenomena and energy dissipation of concealed bracings are discussed. The experiment shows that the seismic performance of RC core walls with concealed bracings is improved remarkably.
Analyses in Seismic Responses of Different Types of Eccentrically Braced Steel Frames
Authors: Hu Ying , Lei Jin Song , Luo Wen Xia
Published: May 2011

In order to research the seismic behaviors of the eccentrically braced steel frames, used finite element software SAP2000 to build 20-storey single frame models with type D, K, and Y eccentrically braces, and did the seismic time history analyses to them. Comparisons were set between different kinds of braces in the distributions of moments, displacements, and accelerations for different layers produced by the EICENTRO seismic wave, TianJin seismic wave and NanJing seismic wave. Also, the analyses were set in the time history curves of displacements and accelerations. The results reveal that: type K is able to control the moments and displacements of the layers; while type Y is good at restricting the acceleration amplified effect, and the seismic behavior of type D is between the former two types.
Theoretical Analysis and Application Research on Grid String Branch Structure
Authors: Mo Zong Yun , Liu Xiao Li , Song Xue Feng
Published: May 2011

According to the thought of beam string structure, pre-stressing structure was presented that it was joined by rigid grid and flexible cable by pole support. It was grid string branch structure. A calculation model of string branch grid was founded. Static and dynamic characteristics of the structure that it was acted by different pre-stress value were analyzed. Through the analysis, the structure displacement and internal forces of rod are improved obviously depending on pre-stress value. The pre-stress value is larger, structure displacement and internal forces of rod are lower. Natural vibration characteristics of the structure are almost not changing, while pre-stress value is changing. When the structure is time history analysis, its response curve accords with general law of structural vibration. Node displacement response of up and bottom chord nodes are not occurred retardation effect.
Effect of Mineral Oil on Sewage Disposal by Biofilm Process Dosing with Enzyme
Authors: Guo Gai Mei
Published: May 2011

The research studied enhanced treatment of sewage from discharging points of rivers by biofilm process dosing with enzyme and the effect of mineral oil on removal rates of the main pollution indexes, and investigated promotion effect of enzyme (including the laboratory developed compounded enzyme and the foreign composite enzyme) on treatment of sewage by biofilm process. The research results indicated that when mineral oil with the concentration of 20mg/L was added to reactor A, B and C, respectively, the removal rates of mineral oil, CODCrand ammonia nitrogen all obviously decreased. Meanwhile, the removal rates of mineral oil, CODCrand ammonia nitrogen were higher in reactor B and C than in reactor A, and the removal rates of them in reactor B were similar to them in reactor C, which indicated that enzyme had good promotion effect on biofilm process during the sewage treatment process.
Dynamic Reliability-Based Seismic Optimal Design of Structures with Tuned Mass Damper
Authors: Huang Tian Li , Ren Wei Xin
Published: May 2011

This paper presents a dynamic reliability-based optimization technique for the seismic design of structures with tuned mass damper (TMD). Firstly, the governing equation of multi-degree-of-freedom structure with TMD is established. Then, the main structure is unfolded by the first mode. Considering that the damping is non-classical and the total main structure and TMD system is un-symmetric, the complex modal analysis is adopted to uncouple the governing equation and the analytical solutions of stochastic seismic response under the Kanai-Tajimi spectrum loading are obtained. Taking the ratio between the first-order modal displacement standard deviation of the structure with TMD and the one without TMD as the objective function, the dynamic reliability of the TMD system displacement as the constraint, the optimal design parameters of the TMD system are obtained through the penalty function method. A 10-story building with TMD system illustrates the proposed dynamic reliability-based optimization method. It is believed that such an optimization technique provides an effective tool for the seismic design of structures with TMD.
An Improved Contact Model for Pounding Simulation of Base-isolated Highway Bridge
Authors: Huang Xiao , Zhu Hong Ping , Hu Zhi Xiang
Published: May 2011

A modified Hertz model with nonlinear damping (Hertz damp model) is proposed for capturing the seismic pounding response of adjacent structures. Relevant parameters in the model are theoretically derived and numerically verified. Then, this model is used to simulate pounding response of a base-isolated highway bridge subjected to near fault ground motions. At the same time, nonlinear viscous dampers are installed between bridge decks for pounding prevention. The appropriate damping coefficient of the dampers can be found by parametric studies. It is shown that nonlinear viscous dampers are effective in reducing the relative displacement between bridge decks. At last, the hysteresis curve, the maximal damper force and stroke are used to demonstrate the behavior of nonlinear viscous dampers. The results indicate that satisfied viscous dampers can be produced to eliminate pounding according to the current manufacturing skills.
An Equivalent Far-Field Dynamic-Artificial-Boundary Condition and its Accuracy Studies
Authors: Wu Yi
Published: May 2011

In order to eliminate some problems of ordinary artificial boundary conditions in soil-structure dynamic interaction analysis at present, such as plenty amount of work required in establishing viscous boundary and viscous-elastic boundary and the expensive computing hours cost in traditional far-field artificial boundary condition, an equivalent far-field artificial boundary condition for dynamic analysis was proposed based on the wave propagating theory and the reflection and transmission principle of wave on the interface of medium by setting a fully-transmitting layer and lower the speed of wave considerably propagating within it. Then numerical simulations and studies of factors affecting accuracy for equivalent far-field artificial boundary condition were conducted with FEM. Researches show that equivalent far-field artificial boundary is as nearly accurate as viscous boundary; it can overcome the problems of viscous boundary, viscous-elastic boundary and traditional far-field boundary mentioned above; it is very convenient to operate and realize; it is very efficient and low-cost in workforce. The equivalent far-field boundary proposed can be applied to engineering dynamic field such as anti-seismic of structures, vibration and impact etc.
Near-Fault Directivity Spectrum for Nuclear Structure Design on Rock Site
Authors: Xu Long Jun , Yang Sheng Chao
Published: May 2011

This study is aimed at evaluating the safety implications of near-fault directivity effect on nuclear structure and facilities designed according to the Chinese code. To this end, a set of near-fault ground motions at rock site with typical forward-directivity effect is examined with emphasis on several key parameters and response spectra. The bi-normalized response spectra in terms of different corner periods are utilized to derive nuclear design spectra. It was concluded that nuclear design spectra on rock site derived from typical directivity records are significantly influenced by both magnitude and distance. The nuclear design spectra specified in the code need to be adjusted to reflect the near-fault directivity effect of large earthquakes.
Research on Factors Influencing the Axial Bearing Capacity of Tubular Joint of Spatial TX-Type Square Steel Tube
Authors: Xia Jun Wu , Xia Xin Qiang , Zhang Ting Ting , Li Yue
Published: May 2011

There are many factors influencing the bearing capacity of spatial joint, whose load-carrying capacity is also more complicated. In this paper, the finite element method is adopted for the tubular joint of TX-type square steel tube to explore the influences on the ultimate bearing capacity resulting from the axial stress of main tube and the loading ratio JAA. The analytical results show that: for the joint with small β, the pressure of main tube will reduce the joint strength, while the appropriate tension is beneficial, but too large tension will lower the joint strength. The loading ratio JAA has significant influences on the joint, and when the ratio is positive, the outer-planar branch plays a very good role in the stiffening effect of the joint.