bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and Finite Element Modeling of Friction Stir Seal Welding of Tube-Tubesheet Joint
Authors: Al-Badour Fadi A. , Merah N. , Shuaib A.N. , Bazoune A.
Published: February 2012

Tube-tubesheet joints are critical in some applications, where contact between shell and tube side fluids is not tolerable. To ensure joint tightness, standards (ASME and TEMA) recommend performing a combination of rolling-or expansion of tube-tubesheet and seal welding. Available techniques for seal welding are based on fusion welding that sometimes results in a number of defects such as cracking and porosity formation, and such defects may take a newly fabricated heat exchanger out of service. In this work, friction stir welding (FSW) was used for tube-tubesheet seal joint and simulated using a 3D thermo-mechanical finite element model (FEM). The model was analyzed using a commercial finite element (FE) package. The model included the thermal effect of the tool workpiece interaction along with axial load, ignoring the metal flow around the tool. The material model took into account temperature dependency of thermal and mechanical properties. The model objectives were to evaluate the temperature distribution and residual stress in the workpiece resulting from the thermal cycle and axial load during welding for various process parameters, and to study how residual stresses in adjacent roller expanded tubes are affected during welding. The FE results show that the maximum temperature at the welding zone does not exceed the solidus temperature (except at high tool rotational speeds); the process can thus be classified as cold working. Moreover, adjacent tubes temperature does not exceed the annealing temperature. An experimental setup was designed and manufactured to show the feasibility of the process in this constrained size joints and to validate the numerical results. A test cell and a special FSW tool were designed and manufactured for this purpose. Many tests were performed with welding quality depending on process parameters.
Structure and Stresses of Large Size Brazed Joints of Cermets and Steel
Authors: Nowacki Jerzy
Published: February 2012

Stresses in brazing joints of different differed in properties were appraised as a result of technological experiments and FEM analysis. Evaluation of microstructure and mechanical properties of large dimensional vacuum brazed joints of Ferro Titanit Nicro 128 sinters and precipitation hardened stainless steel of X5CrNiMoCuNb14-5 using copper as the brazing filler metal. Structure of the joint was described. Shear strength Rt and tensile strength Rm of the joints have been defined. It have been state, that the basic factors decreasing quality of the joint, which can occur during vacuum brazing of the Ferro Titanit Nicro 128 sinter Cu brazing filler metal steel joints are diffusive processes leading to exchange of the cermets and brazing filler metal elements and creation of intermetallic in the joint. It can have an unfavourable influence on ductility and quality of the joint. The effect of joint geometry structure on stresses and deformations as well as on the process of plate cracking has been determined. Results of numerical calculations of three-dimensional models of brazed joints for different sizes of surfaces brazed at a constant width of solder gap are presented. Results of the investigate proved that joints microstructure and mechanical properties depend on filler and parent materials, diffusion process during brazing, leading to exchange of the cermets components and filler metal as well as joint geometry. The thickness of the joints has an essential influence on the values of the local stress and the significant influence on the joint rigidity. In a case of the considered joints the values of the local stress differences have been considerable in dependence of a fixed load manner.
Influences of Tool pin Profile and Tool Shoulder Curvature on the Formation of Friction Stir Welding Zone in AA6061 Aluminium Alloy
Authors: Moosabeiki Vahid , Azimi Ghasem , Ghayoor Mostafa
Published: February 2012

Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the weld quality. Friction stir tool plays a major role in friction stir welding process. In this investigation, it is tried to evaluate the effect of tool pin thread and tool shoulder curvature on FSW zone formation in AA6061 aluminium alloy. In this regard, six different tool pin geometries (threadless triangular pin with/without conical shoulder, threaded triangular pin with conical shoulder, threadless square pin with/without conical shoulder, threaded square pin with conical shoulder) are used to fabricate the joints. The formation of FSP zones are analyzed macroscopically. Tensile properties of the joints are evaluated and correlated with the FSP zone formation. Consequently, it is obtained that welding creates a higher quality compared to other tool pin profiles using the square tool with curved shoulder and having threaded pin.
Graftfast©: Towards the Control of Surface Properties of any Type of Materials by the Grafting of Polymers
Authors: Mesnage Alice , Simon Pardis , Deniau Guy , Herlin-Boime Nathalie , Palacin Serge
Published: February 2012

This document aims at presenting and explaining the mechanism of a simple green process, called Graftfast©, recently developed in order to graft polymer films onto any type of materials. This process is of great interest as it works in a short one step reaction at room temperature, atmospheric pressure in water. Particularly since this method is a redoxinduced process consisting in the reduction of diazonium salts into aryl radicals in presence of vinylic monomer, the involvement of such radicals was investigated. Moreover, this work demonstrates the efficiency of such process for the preparation of functionalized TiO2 nanoparticles. The composition and the grafted polymer quantities were investigated showing the successful grafting of the polymer onto the nanoparticles while conserving their morphology.
Fabrication of Graphene Platelet (GPL)-Epoxy Nanocomposites and Characterization by Nanoindentation
Authors: Colak Ozgen U. , Zandiatashbar Ardavan
Published: February 2012

Main objective of this work is to manufacture the graphene platelet (GPL)-epoxy nanocomposite and to characterize the nanocomposite using nanoindentation technique. Thermal reduction of graphite oxide is the method used to obtain bulk quantities of graphene platelets (GPL) which comprise multiple graphene sheets. Dispersion of GPL in epoxy matrix is done with sonication and high speed shear mixing is used for mixing curing agent and resin. Following the manufacturing of graphene platelet-epoxy nanocomposites, characterization of the material was performed by nanoindentation. Nanoindentation experiments are performed under load or displacement control at different load/displacement rates to investigate rate dependent behavior of the nanocomposite. The primary mechanical properties obtained from the nanoindentation tests which are the hardness and the elasticity modulus are determined.
Effect of Milling Time and Annealing on the Mechanical Response of Mechanically Milled Aluminium
Authors: Aboulkhair Nesma T. , Esawi Amal M. K.
Published: February 2012

Owing to its many exceptional properties, aluminium finds many applications in theaerospace, automotive, building and packaging industries. Enhancing its properties through alloyingor thermal treatments has been the focus of researchers’ interests for a long time. In this work, purealuminium powders were mechanically milled for up to 12 hrs and then were cold compacted andextruded to produce bulk nanostructured material. Both tensile and compressive tests wereconducted and the results compared. Post extrusion annealing treatments for up to 3 hrs wereconducted on additional samples.It was found that increasing the process control agent (PCA) content as well as the milling durationresulted in a finer microstructure and hence enhanced mechanical strength. This was accompaniedby a reduction in the ductility of the material. Moreover, compression tests revealed that thesamples are significantly more ductile in compression than in tension and that the decrease inductility with increase in milling time is less significant than in the case of tension. The differencein mechanical response is attributed to plastic instabilities. Annealing was found to enhance thetensile ductility of the samples without sacrificing strength.
The Study of EDM Parameters in Finishing Stage on Electrode Wear Ratio Using Hybrid Model
Authors: Atefi R. , Amini Saeed
Published: February 2012

In this study, the influence of different electro discharge machining parameters (current, pulse on-time, pulse off-time, arc voltage) on the electrode wear ratio as a result of application copper electrode to hot work steel DIN1.2344 has been investigated. Design of the experiment was chosen as full factorial. Artificial neural network has been used to choose proper machining parameters and to reach certain electrode wear ratio. Finally a hybrid model has been designed to reduce the artificial neural network errors. The experiment results indicated a good performance of proposed method in optimization of such a complex and non-linear problems.
The Effects of Tool Geometry on Machinability of Textile Fabric Reinforced Termoplastic Matrix Composites
Authors: Kuzu Ali Taner , Bakkal Mustafa
Published: February 2012

This paper aims to evaluate the machinability of a novel composite material which is textile fabric reinforced composite. In this study, four different cutting tools with different geometries were used due to the lack of information on tool selection for thermoplastic matrix composites. During machining of this novel composite, the fixture design is essential due to the very low elastic modulus of composite plates about 0.5 GPa. After designing special milling fixture, tests were performed in two limit values of cutting parameters, cutting speed and feed rate. Cutting force results, chip and burr formation were evaluated to determine suitable tool and cutting parameter selection.
Systematical Design of a Refrigerator Foot Height Adjustment Device
Authors: Turan Seda , Durmaz Mehmet , Tacgin Ertugrul
Published: February 2012

Systematic design is an effective methodology which generates possible designs and eliminates them in a step by step manner. The methodology allows designers to generate sub modules and creates relationships or network between these modules to form to functional structure of the design. Due to its capability of reducing development time and that of satisfying customer requirements it has wide application areas. Height adjustment mechanisms for consumer goods industry are special interest for designers and have limited application area due to fact that such kind of mechanisms cannot totally meet customer requirements and they may be too complex to manage. So, different techniques or approaches must be employed to design a specific mechanism for height adjustment. Systematic design approach is employed in this study to produce potential design proposals together with their driving mechanisms for height adjustable refrigerator foot. First stage of systematic approach employed in this study is definition of the height adjustment problem and design requirements. A wide patent research is then completed to seek for existing solutions. Subsystems and functional structure of height adjustment problem arc then formed using "Technical Process Flow" and "Functional Structure Chart". "Morphological Matrix" is created to illustrate each process step and types of design proposals. Last stage is to evaluate the generated design proposals according to the systematic design philosophy to create a novel conceptual design to be patented. Finally, the novel design produced has been manufactured with rapid prototyping technology for further evaluations.
Experimental Investigation on Wear of FDM Processed Part
Authors: Sood Anoop Kumar , Ohdar Rajkumar , Mahapatra S.S.
Published: February 2012

Fused deposition modelling (FDM) is one of the rapid prototyping (RP) processes that build part of any geometry by sequential deposition of material on a layer by layer basis. Unlike other RP systems which involve an array of lasers, powders, resins, this process uses heated thermoplastic filaments which are extruded from the tip of nozzle in a prescribed manner. Present work focuses on extensive study to understand the effect of five important parameters such as layer thickness, part build orientation, raster angle, raster width and air gap on the sliding wear of test specimen built through FDM. The study provides insight into complex dependency of wear on process parameters and proposes a statistically validated predictive equation. Microphotographs are used to explain the mechanism of wear. Finally, the predictive equation is used to find optimal parameter setting through bacteria foraging optimization algorithm (BFOA).
A Method of Analysis to Estimate Thermal Down-Shock Stress Profiles in Hollow Cylinders when Subjected to Transient Heat/Cooling Cycle
Authors: Ali M.A. , Hasan S.T. , Myriounis D.P.
Published: February 2012

An empirical solution for the thermal shock stresses in cylindrical shell presented when cylinder is subjected to heating or re-heating case and down-shock cooling by forced air case. Linear equations are developed to describe the severity of thermal shock loading. When thermal gradient and time period are in consideration, it is shown the equations displays good approximation for major characteristics of the thermal shock stress profiles.
Evaluation of Draw Bead Geometry on Deep Drawing of Complex Rectangular Shape Part
Authors: Beimesl S.M. , Mostafapour Asl Amir
Published: February 2012

The control of blank-holder force (BHF), is one of the main parameters in deep drawing. Fracture, wrinkling and inappropriate draw-in of sheet edges on certain locations are the main defects that occur due to insufficient and not well distributed restraining force of sheet flow into die cavity by BHF. It was demonstrated that appropriate utilization of draw beads with appropriate geometry and location in die could reduce or even eliminate these defects. Achieving an optimum geometry and location of draw beads are main issues in tooling stage that would cause high cost due to trial and error. In this paper, 2D FE analyses to reach draw bead restraining Force (DBRF) for several usual draw beads geometries were performed. 3D FE analyses of deep drawing process of a rectangular automotive panel with complex and parametric geometry with the presence of draw beads were simulated by the use of ABAQUS6.9 commercial FEM package to reach an optimization of best location and also best geometry. Response surface method with full factorial case was employed for optimization. Simulation results were validated by experimental data of deep drawing.
Effect of Deep Cryogenic Treatment on the Microstructure of an Aerospace Aluminum Alloy
Authors: Bouzada F. , Cabeza M. , Merino P. , Trillo S.
Published: February 2012

This paper describes how deep cryogenic treatment at 98K produces changes in the microstructure of a heat-treated aluminum alloy. It was observed how the sub-micrometric particles increased near and at the grain boundaries. This slight precipitation did not produce any modification in static mechanical properties. However, the compressive residual stresses of the material were higher after compared to before the treatment. Both these effects can enhance the life of this alloy through cryogenic treatment.
Research Development and Key Technical on Floating Foundation for Offshore Wind Turbines
Authors: Zhang Ruo Yu , Chen Chao He , Tang You Gang , Huang Xiao Yan
Published: February 2012

The water area in which water depth is deeper than 50m has special advantage in wind turbine generation, because there are the stable wind speed and small Wind-shear. In such sea area, the offshore wind energy generating equipments should be set up on floating foundation structure. Therefore, it is of great significance to study the floating foundation structures that are available for offshore wind energy generation for the industrialization of the offshore wind power generation. In this paper, the basic type and working principles are reviewed for some novel floating structures developed in recent year. In addition, some key dynamical problems and risk factors of the floating structure are systemically analyzed for working load caused by turbine running and sea environment loads of floating structure. The results are valuable for designing the floating structures of wind turbine generation.
Mechanical Behavior of Composite Girder with Perfobond Shear Connector under Hogging Moment
Authors: He Jun , Liu Yu Qing , Zhao Chen , Chen Ai Rong , Yoda Teruhiko
Published: February 2012

The mechanical behavior of the support regions for continuous composite girders with tensile stresses in the concrete slab and compressive stresses in the lower steel profile becomes strongly nonlinear under negative bending moments. A static test on four half-scale model of a steel and concrete composite girders with different shear connectors including studs and PBL under hogging moments was conducted and observed to evaluate the influence of shear connector on inelastic behavior such as flexural stiffness reduction, crack initiation and development in concrete slab. From the test results, the flexural stiffness and loading capacity of the composite girders were improved by PBL shear connector. Higher initial cracking load and crack resistance stiffness of composite girders with PBL shear connector under serviceability limit state was obtained during crack development process. The test specimen could be assumed as full composite section until the ultimate state from load-slip relationship of shear connector. Analytical and experimental studies can serve as a basis for continuous composite bridges design.
Study on the Influence of Beam Rigidity on Continuous Rigid Frame Bridge with Moving Vehicle
Authors: Wang Rong Xia , Chen Xiang Shang , Li Fan , Zhao Shao Wei
Published: February 2012

The continuous rigid frame bridge has been applied widely in our country. But in recent years, over-deflection of beam in this bridge has become an serious problem. This may cause the redistribution of displacement and internal force of the whole structure, especially in dynamic load status. A two-dimensional pile-soil-bridge model is built up in ANSYS based on a factual bridge. The over-deflection is considered as the decrease of beam elastic modulus or rigidity. The displacement and internal force of key parts are analysed in static and dynamic vehicle load. The study shows that over-deflection will reduce the first three natural vibration frequency, weaken the sensitivity of bridge to dynamic load. In dynamic load status, the displacement and internal force will be influenced by beam rigidity.
Key Technology of Construction Control of the Middle Pylon of Taizhou Bridge
Authors: Yang Ning , You Xin Peng , Zhang Yong Tao
Published: February 2012

The Taizhou Yangtze river bridge is a suspension bridge with three pylons and two 1080m long navigation spans. The middle pylon with height 191.5m is made of steel. The general construction procedure of the middle steel pylon is briefly introduced. Construction control of the pylon is carried out during the whole process of the construction. The control concept is extended to the manufacture stage besides the installation stage. The manufacturing alignment errors are strictly controlled in precast process of the segments in factory, and the alignment error is identified and predicted precisely during the installation stage. The adjusting joints are adopted to adjust the accumulated errors, which ensure that the steel pylon alignment could satisfy the as-built precision requirements.
Static Analysis of Prestressed Concrete Bridge with Slant-Legged Rigid Frame
Authors: Li Xiao Ke , Liang Xi Jian , Liu Shi Ming
Published: February 2012

This paper introduces the main dimensions and drawings, and discusses the static analytical results of a prestressed concrete bridge with slant-legged rigid frame. The numerical mode of this bridge was built by the specialist FEM software. The results show that the central span of box-beam and the slant-legs forms an arch-like structure which brings these members into compressive-bending states, the side span of box-beam is in bending. For the box-beam, the internal forces mainly come from the dead load, the prestress effects and the vehicle load. The sedimentation of supports and the entire warming or cooling have certain influence on the side span box-beam and the slant-legs. Decreasing the shrinkage and creep of concrete is also important for this bridge.
Case Study of Ground Fissures Generated by Liquefaction Following the Wenchan Earthquake
Authors: Yang Fa Hai , Liu Wei Jun , Yang Xiao Ling
Published: February 2012

Ground failure caused by liquefaction is a major cause of earthquake damage and casualties during many history earthquakes. The gravels liquefaction extensively occurred following the 2008 Wenchuan Ms8.0 Earthquake, and 70-80% liquefied sites generated lots of 100 meter to hundreds kilometer long and 5 centimeter to 50 centimeter wide ground fissures, which intersected house, farmland, etc. and caused serous damage. The mechanism of the building damage and ground fissures were investigated by borehole drilling and Multi-Channels Electricity Resistance Test. The detailed in-situ tests and comparison show that: (1) The building, whose foundation intersected by liquefaction, suffered more severe damages than its surrounding buildings; (2) The abundant ground fissures were generated by gravels liquefaction rather than the raptures or secondary faults; (3)The fundamental conditions for the generation of ground fissures by liquefaction are: flat ground surface (slop less than 3%), horizontal non uniform distribution of liquefiable soils.
Efficient Elastic Modulus Adjustment Procedure for Limit Analysis of Spatial Frame Structure
Authors: Yu Bo , Yang Lu Feng
Published: February 2012

An efficient elastic modulus adjustment procedure to evaluate lower-bound ultimate bearing capacity of spatial frame structures was proposed based on the strain energy equilibrium principle. Four strategies to determine the elastic modulus adjustment factor were developed based on the fixed strain method (FSM), circular arc method (CAM), strain energy conservation law (SECL) and strain energy equilibrium principle (SEEP). The precisions and convergent properties of above four strategies were quantitatively investigated through two numerical examples. The results show that the efficiency and accuracy of the SEEP are of most acceptable.
Interpolation Technology and its Application in Damage Analysis of Bridge Structure
Authors: Ding Ke
Published: February 2012

The damage analysis based on the modal parameters usually need to compare the test data with the computed data by theoretical analysis. In bridge structure damage analysis, it is impossible that the sensors are set at every node. So the test data need to be extended to every node by using interpolation technology. In the paper, three interpolation methods, cubic interpolation method, cubic spline interpolation method and sinc interpolation method, are introduced. Their applications in bridge structure damage analysis are discussed. The experiment results show that the best interpolation method is cubic spline interpolation method. Using the data processed by interpolation technology can well obtain the damage location of bridge.
Effect of Cooling Pipe in Thin-Walled Hydraulic Structure during Construction
Authors: Wang Zhen Hong , Zhang Guo Xin , Wang Zhao Gang , Liu Yi
Published: February 2012

In view of the problem of concrete crack in the period of construction, this paper introduces the cause and the forming mechanism of crack in thin-walled concrete structure and points out that the difference between the inside and outside temperature at early stage and the basic difference of the temperature at later stage are considered as the main factors influencing the phenomena. This paper puts forward the application of pipe cooling which is used in the mass concrete to the thin-walled concrete structure. In doing so, the difference of the internal and surface temperature is reduced and the appearance of cracking is avoided. Under the basic theories of temperature field and stress field of concrete, the 3-D FEM with the numerical algorithm of pipe cooling is adopted to simulate the thermal field and stresses field of concrete aqueduct during construction and the result shows that good effect of temperature control and crack prevention is achieved in thin-walled concrete structure. At the same time, water cooling pipe has many merits including simple operation, easy adjustment, high adaptability, and low cost
Analysis of Bridge Dynamic Load Tests
Authors: Chen Jing Xi , Xia Tao , Huang Jun , Zhang Guang
Published: February 2012

This article is undertaken with the results of the detection of structural highway bridge in the west of Ezhou subsidiary line after completion and its analysis of completing and analyzing bridge dynamic Load Tests, in order to introduce three means of tests: the pulse tests, vehicle tests and bump tests. Finally we discuss the advantages and disadvantages, as well as the prospects.
Research of Self Pre-Stress Test of Concrete-Filled Steel Tube Arch Rib
Authors: Huang Fu Wei , Yang Hai Ting
Published: February 2012

Indirect test method of installing vibrating wire strain gauges as sensors in outer surface of steel tube rib is adopted to carry out the research of concrete-filled steel tube (CFST) self pre-stress test for a half-through CFST arch bridge with a main span of 240m. The results show that indirect test method is a practical approach for self pre-stress test, and the measured value of self pre-stress from this method is much smaller than that of being theoretically calculated by concrete free expansion ratio.
Discussion on the Sound Radiation Coefficient of Building Materials
Authors: Yang Yan , Huang Xian Feng , Liu Jun
Published: February 2012

According to the definition of the sound radiation, a theoretical model is developed for acoustic radiation from a plate into air space. Then, the calculation for acoustic radiation coefficient at different frequencies and critical frequency of building members are carried out, also the radiation coefficient curves varied with frequency are gained. Comparison with the results of the radiation coefficient with different thicknesses and materials, the results show that: the sound radiation coefficient is so low to be neglected below the critical frequency; while it tends to a constant value of 1 above the critical frequency, and the maximum value occurs at critical frequency. Due to influence of radiation on the sound transmission in a structure, sound radiation coefficient plays a significant role on the option of sound insulation materials during the practical engineer.
Long-Term Bonding Strength between Flue Gas Desulfurization Gypsum and Polymer Cement Mortar
Authors: Mu Ru , Wang Ling , Tian Wen Ling , Cao Wei
Published: February 2012

The uncertainty of long-term bonding strength of flue gas desulfurization building gypsum and cement based construction materials is the major issue impeding the application of flue gas desulfurization building gypsum in construction. A polymer cement mortar is suggested to get high bonding quality with flue gas desulfurization building gypsum. Long-term bonding observation has been carried out to verify the bonding performance of suggested polymer cement mortar with flue gas desulfurization gypsum. The results show that the bonding strength is up to 3.0MPa, and the bonding between them is durable.
Study on Optimum Mixing Ratio and Properties of Lightweight Soil Using Recycled Sludge
Authors: Wang Guo Cai , Jin Fei Li , Sha Ling , Huang Le Ping
Published: February 2012

In view of the large amounts of discarded sludge produced in the process of engineering construction, this paper proposes and makes use of the discarded sludge and compounds a kind of lightweight soil of adjustable intensity. In order to get the physical properties of the lightweight soil, a series of laboratory tests is made to investigate the lightweight EPS beads compounded soil using the sludge as raw material soil, cement as the solidification material, and the effect of cement content, EPS beads volume fraction and curing age, etc. on the density and strength is analyzed. The change regularity is obtained of the density and strength parameters of lightweight soil using recycled sludge with each factor. The research results can provide fundamental basis for the application and quality control of engineering waste soil, and can establish a theoretical foundation for further development and utilization.
The Experimental Study on Reinforced Concrete Short-Columns Restrained by Corroded Stirrups
Authors: Li Qiang , Niu Di Tao , Liu Lei
Published: February 2012

The impact of stirrup corrosion on the constraint of corroded reinforced concrete(CRC) column is an pressing problem that needs to be solved. In this paper, 12 corroded CRC short-columns and 3 uncorroded CRC short-columns with dimension of 150mm×150mm×450mm have been prepared for the axial compression experiment. Through the experiment, the total cross-section stress-strain curves of the short-columns were measured under different degrees of stirrups corrosion, and the effects of corrosion rate of stirrups on the shape of the total cross-section stress-strain curves, bearing capacity, deformation and the mechanical parameters of confined concrete have been investigated. According to the results, the corrosion of stirrups has reduced their section, changed the material quality and damaged the concrete cover, which reduces the constraint to the core concrete; the shape changes of stress-strain curve illustrate that the destructive form of short-columns developed form ductility damage to brittle failure gradually.
Application of BP Neural Networks in Damage Prediction of Multilayer Medium Penetration and Blasting
Authors: Liu Xiao Ling , Lei Ting , Yao Yong
Published: February 2012

Back-propagation method (BP method) is the supervised learning algorithm that is the most widely and successfully used in feed forward network nowadays. This paper dealt with the penetration and blasting experimental data by BP Neural networks, including of the influence of the velocity and attack angles to damage of multilayer medium penetration and blasting. Through handling of the experimental data by the BP Network system, coupled effects of quantity of explosive and buried depth can be uncoupled. The curves of infundibular crater radius vs. quantity of explosive and infundibular crater depth vs. buried depth of explosive was given. Base on computing results, it is shown that the neural networks method can be used to predict the damage of multilayer medium penetration and blasting.
Study on the Prediction Method of Tunnel Surrounding Rock Pressure Based on the Theory of Progressive Destruction
Authors: Wang Suo
Published: February 2012

In order to predict tunnel surrounding rock pressure, this paper puts forward a series of dynamic numerical simulative model on the tunnel excavation. According to the change of rock damage in the construction program, it adjusts dynamically the mechanical material parameters of surrounding rock. So the model achieves the purpose which is controlling and simulating the process of tunnel progressive damage. In accordance with the numerical simulative results, it analyzes the relationship between the rock parameters with the plastic strain, radial displacement. Then this paper proposes a prediction method of tunnel surrounding rock pressure based on the theory of the progressive damage and method of characteristic curve. Finally, it compares the pressure on the numerical simulative models with on the site date, and it proves that the prediction method has practical engineering value.
Centrifuge Modeling of Vertical Bearing Behavior of Bolt-Shotcrete Supported Slope
Authors: Li Wei , Cao Jie , Zheng Rui Hua
Published: February 2012

This paper presented the results of centrifuge model tests conducted to investigate the behavior of cohesive soil slopes under the vertical surface load, considering the bolt-shotcrete supported slopes. The cement layer and bolts influenced the behavior of the slope when surface vertical load was applied. The analysis of bearing capacity and displacement threw light on the failure and displacement distribution of the slope.
Predict Model for Water Content of Dredged Sludge under the Aeration-Vacuum Condition
Authors: Gao Yu Feng , Zhang Qin Yu , Zhou Yuan , Zhang Ying
Published: February 2012

The clogging problem occurs in the dewatering projects of sludge with high water content and high clay particles content can be solved by the aeration-vacuum dewatering method. And the water in the sludge can be separated out quickly. Through the dewatering model test of the sludge with this method, the effects of vacuum degree and aeration rate on the dewatering results are studied. The relationship between the initial and final water content is got under the aeration-vacuum condition. Through the fitting analysis of the dewatering curves, the predict model for water content of dredged sludge is presented. And the effect mechanism of the vacuum degree and aeration rate are analyzed.
The Study of Large Vibration Compaction on Soil-Stone Mixture Poisson′s Ratio with Wave Velocity
Authors: Zhang Yu Hui , Zhang Xian Min
Published: February 2012

The equipment of large vibration compaction was designed and adopted to simulate the changes of mechanical properties of mixture, by large laboratory vibration compaction test under the condition of different water content and different soil-stone proportion with sandy soil, silt soil and low liquid-limit clay. The deformation capability in each direction of foundation mixture in different compactness was studied by analyzing poisson′s ratio. The change law of poisson′s ratio, shear-wave velocity, longitudinal wave velocity of mixture in different compaction degree were revealed. Model of correlation between poisson′s ratio (μ) and ratio of the S to P wave velocity (ε) was proposed. The model was verified by extra test. The results show that the relationship between μ and ε is not accord with theoretical formula because of special particle shape and distribution of the soil-stone mixture. The change regularity of mixture poisson′s ratio in different conditions can be reflected well by the model. The new method of field test of poisson′s ratio in soil-stone foundation with ratio of the S to P wave velocity is proposed. The conclusion is valuable in poisson′s ratio study of soil-stone mixture.
The Engineering Accident Analysis of Cast-In Situ Bored Pile
Authors: Tang Bin , Wang Ting , Shan Zi Ning
Published: February 2012

Abstract: Cast-in situ bored pile is a common form of pile foundation and widely used in road and bridge engineering in China. Because of complex cast-in situ bored pile construction process, high technical content requirement, vulnerable to the impact of human and environmental factors, cast-in situ bored piles prone to various kinds of quality problems in the construction process, such as drilling deflection, drilling hole collapse and diameter reduction, wrong identification of pile-end’s bearing stratum, catheter tube blockage, reinforcement cage floating, pile breaking, pile silted, etc. These problems often make it difficult to meet the design requirements into a pile formation, and difficultly to remedy. In this paper, Zhoutian Zhenjiang bridge at Shaoguan City, Qujiang to Nanxiong highway A03 contract bid package cast-in situ bored pile foundation engineering encountered in the construction collapsed hole, inclined hole, catheter tube blockage and other issues for example to analyzes the cause of cast-in situ bored pile engineering accident, made appropriate preventive measures and processing method.
Non-Linear Hoek-Brown Shear Strength Reduction Technique Considering the Effect of Dilation
Authors: Ai Ting , Zhang Ru , Ren Li , Fu Wen Xi
Published: February 2012

In order to implement the non-linear Hoek-Brown (HB) shear strength reduction (SSR) on commercially available softwares, this paper derives the relationship between the Drucker-prager (DP) criterion and HB criterion under the condition of plane strain. The equivalent DP parameters can be approximately estimated after serious transformations of parameters between the HB and Mohr-Coulomb (MC) yield functions. To assess the effect of dilation on the stability of slope, the non-associated flow rule, which cannot be contained in the existing limit equilibrium methods, is selected in our analysis, and the SSR-based results of a simple slope indicate that: If the angle of dilatancy ψ is taken to be zero, the factor of safety calculated by the SSR method is very close to that by the limit equilibrium method; if ψ is greater than zero, the factor of safety calculated by the SSR method is greater than that by the limit equilibrium method, and the effect of dilation on the stability of slope can be approximately described by a liner function.
Study on Safety Factor of Loess Cave Dwellings with Pitted Courtyard in Different Rainfall Infiltration
Authors: Han Jia Ming
Published: February 2012

Baishe villagers have lived in loess cave dwelling with pitted courtyard for hundreds of years in Sanyuan County of China .Rainfall infiltration badly destroyed the habitation in recent years so that the study is very important on security and stability of the loess cave dwelling. By field measurements, the sizes of local cave dwellings were mastered and variation was grasped of average annual and monthly rainfall. The physical and mechanical parameters were acquired with loess samples in different water content by the conventional and triaxial soil test. At the same time, based on the literature data, the relationship was established between rainfall and water content. Safety factor was defined for loess cave dwellings in different depths utilizing the expressions of the surrounding rock loop stress and the Mohr-Coulomb theory. The variation of stability of loess cave dwelling could be ultimately analyzed under different rainfall.
Coulomb-Cam Model for Dilatancy and Work-Softening of Sand
Authors: Jiang Zhu Jin , Cai Wu Jun , Ling Dao Sheng
Published: February 2012

Cambridge model gets the extensive application, which has advantages of rigorous theoretical derivation and model parameters which can entirely be obtained by triaxial tests, while it has deficiencies of the narrow applicative scope and describing the dilatancy hardly. As the most widely used strength theory, Mohr-Coulomb model can directly represent shear strength of soil material simply, without consideration for compression deformation yet. On account of the critical state of dilatancy defined comprehensively, this paper based on the description of dilatancy combines the advantage of Cambridge model and Mohr-Coulomb strength theory, applying to compression deformation and conciseness of Mohr-coulomb model, reflecting shear deformation and puts forward an elastic-plastic model—Coulomb-Cam model. At last, this constitutive model, proved by the contrast of numerical simulation and GDS triaxial tests is of the priority in representing the dilatancy and work-softening rationally.
Stability Analysis of Landfill Liner System Based on Numerical Simulation
Authors: Gao Jun Li , Zhang Meng Xi
Published: February 2012

Although ABAQUS is one of the most powerful non-linearly finite element software, it is lack of interface Duncan-Chang constitutive model, which is one of the generally used soil numerical method in China and worldwide. Subsequently, ABAQUS can not widely used in soil numerical method. To improve this situation, a new interface Duncan-Chang constitutive model was developed based on the preliminary direct shear test results through secondary development. Combined with practical engineering, the efficient model was established. Compared with smooth geomembrane/geotextile interface, the shear stress of reinforced geomembrane/geotextile interface increases obviously, and the sliding displacement decreases obviously. It supports our assumption that the reinforced geomembrane can improve interface shear strength and stability of liner system.
An Investigation on the Interfacial Transition Zone in Concrete Using SEM
Authors: Yang Hsi Chi , Cheng Miao Ying , Wang Jung Pin
Published: February 2012

The technique of linking the SEM (Scanning Electron Microscopy) photographs taken around the interfacial transition zone area is applied to observe the development of hydration products for aggregate and paste at the different curing ages. This research first chooses the aggregate with clay properties not containing the calcium ion, and then observes the hydration products (such as CH, C-S-H) of calcium ion on the aggregate. Finally it assesses if the aggregate will produce ion exchange with cement and generate the hydration products. The very small samples to be observed are taken from the concrete compressive test specimen and must include both aggregate and paste. They are wiped with alcohol to have better pictures before shooting SEM. Initially, the interface of aggregate and paste is sought using 2000x magnification. However, the hydration products on either side of the interface with a range of 50 μm are observed using 10000x magnification. From the results, it is found that aggregate has not interacted with cement paste to produce hydration products and the bond stress of aggregate and paste is controlled by hydration products of paste.
The Mathematical Foundation of Rock Electrochemical Impedance Spectroscopy
Authors: Wang Hong Fang , Hu Jiang Chun , Yuan Zhen Xia
Published: February 2012

The electromagnetic characteristics of rock and ore play an important role in resources, engineering and environmental fields. The high frequency part of rock electrochemical impedance spectroscopy can reveal its crack characteristics according to the test results and rock physical model and equivalent circuit. The mathematical foundation of high frequency part of rock electrochemical impedance spectroscopy is studied, and the ideal Nyquist figure is obtained from that, and the response characteristics of rock electrochemical impedance spectroscopy volume arc are been proofed. It provides the theory basis for further study rock electrochemical detection technology.
Optimal Design of Post-Processing Technology Based on Bearing Capacity Control
Authors: Tong Huai Feng , Xie Bing
Published: February 2012

The optimal design theory of the post-processing technology of thick filling area is based on the characteristics of small non-sand concrete pile, to research the production and development process of stress and strain of foundation soil in the course of drilling and grouting, and thus to optimize the key technical parameters of the post-processing technology. In this paper, on the basis of the analysis of consolidation process and treatment mechanism of the post-processing under the conditions of saturated soft soil, the research of optimal design of the post-processing technology on the control of consolidation degree and bearing capacity is completed, which is of reference for the design and construction of the post-processing technology.
Model Test Study on the Effect of Vertical Lode on Horizontal Bearing Capacity of Disk Pile
Authors: Meng Fan Li , Sun Guang Yu , Lu Cheng Yuan
Published: February 2012

In order to study how it influence the horizontal bearing capacity of the disk pile when there exists a vertical load, a group of model tests has been designed. Three double-disk piles were used in the test, and the distance of the two disks is 5 times as the disk diameter. First drew a vertical load V=200N/300N/400N on the top of pile1/2/3 respectively, then put on the horizontal load stage by stage. And by the test, we can study the differences of the pile bearing properties such as changes in the pile bending moment, the horizontal and vertical deformation on the top. Experiment showed that when the vertical load is quite small（V=200N、300N）, the existence of vertical load has little to do with horizontal bearing capacity. When a vertical load increases to a certain value（V=400N）, The maximum bending moment and horizontal displacement of the pile under the same horizontal load reduce, which indicates that the disks of the pile play a significant role in bearing combined loading.
Thermal Effect on Consolidation for Saturated Porous Solid
Authors: Guo Shao Hua
Published: February 2012

The heat and stress equilibrium equations of anisotropic media, coupled to the mass conservation equations of fluid, are studied here based on the standard space of physical presentation for consolidation of anisotropic saturated soils, in which a new compressible thermal constitutive model of soils is induced. The uncoupled diffusion equation of pore water pressure for anisotropic saturated soil affected by heat is deduced. The results show that the consolidation coefficient of saturated soils is affected by both anisotropic subspaces of soil and coupling coefficient between fluid and solid, and also thermal coefficient and thermo-coupling coefficient. Based on these laws, we discuss the consolidation behaviour for isotropic soils.
Study on the Election of Construction Schemes for the Entrance Segment of Tunnel with Unsymmetrical Loading through Large-Span Thin-Dover
Authors: Zeng Fang Jin , Yan Ji Yang , Deng Tong Fa
Published: February 2012

Jiulian-mountain tunnel is an very important project for a section of Longyang Jiangxi in Da-guang highway. Because Jiulian-montain tunnel has a series of geological problems, like shallow-depth, bias-pressure, big-span,water-rich, rock burst and so on, which is a typical long - wide highway tunnel grew up under complex conditions, construction of the entrance segment is extremely difficult and slow in progress.In order to efficiently accomplish the construction of tunnel on time, it is necessory to elect rational construction scheme of the entrance segment. The numerical simulation for three construction methods,which are benching tunneling method、 method of core-keeping cut in stages and CD method , are carried out by means of Three-dimensional fast lagrangian analysis of continua method(FLAC3D) in this paper. Based on the result of the numerical simulation analysis and contrast, some conclusions and suggestions are proposed, some gist are offered in order to choose the construction method rationally ,and arrange the construction order scientifically, and control the construction pace optimally, and reduce the harm of the construction .
Basic Analysis of Homogenous Slope Stability by Finite Element Method Based on Plaxis
Authors: Li Jia Yu Tong , Shi Ke Bin , Yan Xin Jun
Published: February 2012

This article analyze the slope stability by strength reduction method named Phi-c which supplied by FE software PLAXIS. The reduction factor is suggest to be the safety factor of the slope at the moment when the slope reaches instability, the numerical non-convergence occurs simultaneously. The position of sliding surface and dynamic simulation of instability can be obtain as well. This article has compared the results calculated by other methods Bishop and ABAQUS with difference between 2%-3% which attest to its accuracy and practicability in engineering.