bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability Analysis of Backfilled Gravel Subgrade Slope with FEM Strength Reduction
Authors: Zhang Kun Yong , Feng Tu Gen
Published: May 2011

The current study was implemented to evaluate the backfilled gravel subgrade slope stability of a highway, China. Typical crossing section in Jiling Province was evaluated by using the finite element based strength reduction method. The calculation code was developed based on BCF, which was programmed for 2D finite element analysis on soil stress-strain analysis. The Duncan-Chang nonlinear constitutive model was employed to describe the stress and strain relationship of the soils. The safety factor calculated by the strength reduction method was compared with traditional limit equilibrium slice Bishop Method.
A Simplified Method for Evaluating Earthquake-Induced Differential Settlements of Buildings on Natural Subsoil
Authors: Chen Long Wei , Meng Shang Jiu , Yuan Xiao Ming , Sun Rui
Published: May 2011

In terms of the physical mechanism and features of the dynamic soil-structure interaction during earthquake excitation, a simplified procedure for evaluating the earthquake-induced differential settlement of buildings on natural subsoil is presented. It takes into account of the irregularity of incident seismic waves and the different distribution of vertical dynamic stresses caused by seismic loading under the two sides of building base. Instead of FEM the simplified method based on the layer-wise summation method is used to calculate the settlement of the subsoil with building presence. The cone model proposed by Meek and Wolf is adopted to calculate the dynamic stress distribution under the building. The residual strain potential model of soil under irregular loading and the modulus-softening model are employed to calculate the permanent deformation of subsoil. The simplified method can consider the combined effect of soil, structure and seismic wave reasonably and describe the developing process of differential settlement. The results of large shaking table tests are consistent with the corresponding calculated results.
Modeling of Asymmetry Sedimentation of Foundation Induced Cracking of Masonry Wall with Openings
Authors: Lin Hai Xiao
Published: May 2011

The paper presents a numerical investigation of cracking of masonry wall with openings resulting from the asymmetry sedimentation of foundation. Two causes including end sedimentation and middle sedimentation are considered. The cracking process of the masonry wall with openings can be observed. The results indicate that different cracking patterns can be obtained with different sedimentation locations. Only oblique crack initiates and propagates when sedimentation occurs at end of the wall. A ski slope with the tips of the crack pointed outward can be obtained when sedimentation occurs at the middle of the wall.
Slurry Shield Tunnelling in Clayey Soils: Typical Problems and Countermeasures
Authors: Zhang Zhong Miao , Lin Cun Gang , Wu Shi Ming
Published: May 2011

The distinguishing characteristics of clay are high cohesion and low permeability. For slurry shield tunnelling in clayey soils, favorable aspects are that slurry cake with low permeability can be established more easily and effectively at the excavation face thanks to clay’s high cohesion, which is advantageous for stability of excavation face, and long stand-up time of clay offers enough time for backfilling of the tail void before collapse of surrounding soils, thus lessening ground volume loss. However, some typical problems are encountered due to clay’s high cohesion and low permeability. One primary problem is the clogging of slurry pipeline, once in case of which, slurry pressure will fluctuate severely, thus inducing unstable condition at the excavation face. In extreme cases, the pipeline bursts and soils at the excavation face collapse towards the cutterhead for immediate drop of slurry pressure. Another common problem is clay’s adhesion to the cutterhead, which weakens the excavation efficiency of cutterhead and limits advance rate of the shield machine. Tunnelling will inevitably disturb surrounding soils and excess pore water pressure occurs. In clayey soils, due to clay’s low permeability, it usually takes quite a long time for the excess pore water pressure to disperse completely. The consolidation settlements associated with pore water dispersing account for a large percentage of the total settlements. Accumulated ground settlements threaten structures and pipelines nearby. For these problems encountered during slurry shield tunnelling in clayey soils, both preventive and counter measures are put forward in detail in this study. The proposed measures can be used as a reference to avoid, mitigate and deal with problems encountered during slurry shield tunnelling in clayey soils.
Critical Load Analysis of Double-Hinged Circular Steel Arch In-Plane under High Temperature of Fire
Authors: Han Yu Lai , Sun Bai Tao , Ju Zhu , Wang Yong Gang
Published: May 2011

This paper addresses the stability behaviour in-plane and the critical load of the double-hinged circular steel arch when subjected to elevated temperature caused by fire, the study is restricted to the thermoelastic structural response of the steel material and therefore the high-temperature effects of yielding are not considered. In order to model structural response of the steel arch under thermal loading, some significant factors such as the degradation of the stiffness of the steel arch prior to yielding at elevated temperatures is taken into account, the formulation of critical load is proposed and their variation trends with temperatures is analysed. The proposed method has significant potential for use in the analysis of steel arches subjected to uniformly distributed load at elevated temperature and can provide a foundation for codified procedures in design.
Research on Rock Burst Loading Test and PFC3D Numerical Simulation
Authors: Zhou Yu , Wu Shun Chuan , Wu Qing Liang , Ma Yu Tao , Gao Yong Tao
Published: May 2011

During the tunnel excavation in Zhang-Shi Expressway 2nd-Stage Project, rock burst phenomenon has occurred. Limy dolomite obtained from tunnel rock burst area is used to conduct laboratory loading rock burst test with simulation system of deep rock burst. Simultaneously, based on Particle Flow Theory and PFC3D program, a load-unload code is developed by fish language embedded in PFC3D to carry out simulation of laboratory loading rock burst test. Laboratory test result shows that the rock burst type and intensity of specimen are lagged and severe, respectively; During the test process, a spot of particles eject from the exposed surface; Obvious slabbing phenomenon can be seen on the exposed surface and the separate face of rock slab is parallel to the direction of maximal load σ1 as consistent with the actual phenomenon of engineering rock burst. In the loading rock burst simulation, the load grade, stress-step curve and failure mode of rock burst are almost consistent with the laboratory test. This simulation method describes the failure process actually and subtly, and reveals that the specimen fracture mechanism of loading rock burst is tensile type. Finally, some differences between loading and unloading tests of rock burst are discussed.
Theoretical Analysis and Experimental Research on Upward Capacity of Screw Anchor
Authors: Fang Yan Feng , Gao Hua Xi , Duan Wei Wei , Sun Zhong Jian
Published: May 2011

Based on eight groups of uplift tests for screw anchors with different embedded depths and different plate sizes, a method is given to compute the bearing capacity of screw anchor within critical depth in coarse sand according to analysis on force transmission route and failure characteristics. Within critical depth, bearing capacity of screw anchor is proportionate to embedded depth and the area of screw plate, and the failure surface is inverse triangle in shape. Beyond critical depth, the bearing capacity of screw anchor won’t increase with depth, and the failure surface is funnel in shape. Critical depth is about 10 times the diameter of screw plate. In both cases, the include angle between failure surface and the vertical plane equals to 0.5 time the friction angle of the soil.
Experimental Study of Damage Variable Law of Bridge and Tunnel with Underlying Goaf during Expressway
Authors: Liu Xiu Ying , Di Guo Ping
Published: May 2011

This paper takes geological conditions of the Li—Jun expressway by Kang JiaGou and Tong De coal mine goaf as prototype, using the simulation experiment of similar material, simulates the formation process and distribution of the mined rock fracture and the damage variable of the mined rock by using the simulation experiment of similar material, At the same time, It researches the evolvement law of rock’s fracture network in caving zone, fractured zone over goaf using fractal geometry theory. It analyses the damage variable law in caving zone, fractured zone using the damage mechanical theory, and found the relationship of damage variable and mined width. The conclusion of the experiment indicates: with the advance of the working surface, the fractal dimension of the mined rock crack goes through small → large →small, and stable process of change. In the identical push distance of the working surface, fractal dimension of caving zone is 1.0—1.2 times of fractured zone. With the advance of the working surface, damage variable increases gradually, under the identical mined width, damage variable of caving zone is greater than fracture zone, caving zone is about 1.04—1.11 times of fracture zone. Damage variable of goaf central zone is greater than edge.
The Soil Plug Failure Analysis during the Suction Penetration of Bucket Foundation
Authors: Qi Jian Feng , Song Xue Lin , Li An Long
Published: May 2011

A physical model test is conducted to study the hydraulic gradient and soil plug development during the suction penetration of bucket foundation in the silts. Furthermore, a FEM simulation is carried out by changing the geotechnical parameters and constitutive model to deeply study the suction penetration mechanism. Through the comprehensive analysis, the results indicate that the seepages inside and outside the bucket foundation are the direct reasons for the formation of soil plugs, and that there are the high hydraulic gradient and the safety mechanism preventing soil flow failure for the silts in the bucket foundation. The seepage changes not only the permeability of soil body but also the physical and mechanical properties, and enhances the rheological property and time effect. Thus, the soil plug failure is not seepage failure, not unloading expansion yet, is a complex deformation failure mode under the protection of safety mechanism of bucket foundation.
3D Visualization Technology for the Influence on the Surrounding Environment Caused by Excavation
Authors: Liu Zhen , Zhou Cui Ying , Chen Heng , Dong Li Guo
Published: May 2011

On the basis of visualization of 3D stratum, deep excavation simulation is accomplished by combining with numerical analytical method, Excavation effect on surrounding environment is analyzed. By using experimental or semi-experimental models, the settlement values and their distribution features, which are caused by excavation, are discussed, by using 3D FEM, the horizontal displacement of excavated foundation ditch is calculated, and the OpenGL technology and triangle split arithmetic are chosen to implement the construction and splitting of 3D strata, the excavating process and its influence on the surrounding environment are ultimately realized. By comparing with engineering cases, the validity of analysis model and implement method are shown to be correct, feasible, and efficient.
Local Analytical Solution of One Dimension Consolidation Equation
Authors: Feng Bo , Zhan Run Tao , Zhou Feng
Published: May 2011

One dimension consolidation equation can be transformed into a fractional differential equation by Laplace transform. The transformed equation can leads to a simple relation between pore water pressure and its time revolution. When local rate of change of the pore water pressure is determined, the local pore water pressure can be obtained without having to solve the consolidation equation within the entire domain. The simplicity of the solution procedure is highlighted considering by a example..
Research on Factors Influencing Characteristics Experimentation and Mechanism of Rheological Parameters of Soft-Soil
Authors: Hu Hua , Zhou Xiao Zhen
Published: May 2011

Soft-soil has obvious rheology character, it will induce subsidence distortion, landslide etc serious geotechnical engineering and geologic disasters, and make severe threaten to stability and security of projects. The initializing shear stress and viscosity of sullage soft-soil are tested under static load, and the influencing characteristics are analyzed of which the percentage of clay and water affect the rheological parameters. The mechanism of which the percentage of clay and water affect the rheological parameters are opened out by using the theory analysis and technology of structure micrograph..The research results have have theoretic and practical significance for us to analyse changing disciplinarian of rheological parameters, reinforce soft-soil foundation, raise bearing capacity and whole strengthen of soft-soil.
Study on On-Site Test of Vertical Bearing Behavior of Rigid Pile Composite Foundation for High-Rise Buildings
Authors: Tao Jing Hui , Liang Shu Ting , Gong Wei Ming , Wu Chun Liang
Published: May 2011

To study the working behavior of a rigid pile composite foundation of high-rise buildings, an in-situ loading test and stress test on piles and soil were carried out. According to the test results, the stress distributions and variations, load transferring characteristics, and stress distributions of piles were analyzed. The results showed that the piles with the formation of non-soil compaction technology can consolidate soil among piles. When the load level was greater than 240 kPa, a better consolidation effect can be obtained. The development negative friction at the top of piles was relevant to the load level. The adjustment effect of cushion on the composite foundation was mainly embodied before the load level reached the characteristic bearing capacity of the composite foundation. Under vertical load, the stress distributions along the internal and external sides of pile shaft were different and the loading plate would bring influence to stress distributions of the pile shaft. The influence range was from the middle to the top of the pile. Based on the test results, it is recommended to reduce the evaluation standard of the bearing capacity determined in the pressing plate test. The results can provide a reference for similar engineering.
Numerical Simulation Analysis of a New Pressured Multi-Branch Bored Pile
Authors: Zhang Ming Yi , Kou Hai Lei , Zhang Wei
Published: May 2011

Pressured multi-branch bored pile is a new pile on the basis of squeezed branch reaming pile improved, it is a new pile technology focus on many advantages of the static pile, driven cast-in-place pile, belled pile and multi-branch bored pile. Pressured multi-branch bored pile has high bearing capacity, small settlement, cost-effective advantages of better. Numerical simulation of pressured double-branch pile on the vertical compression with ANSYS finite element analysis software obtained the alternate variation of the lateral friction and tip resistance of pile under the vertical load. Many branch of pile constitute multi-pivot friction and end-bearing pile, the bearing branch bear mainly bear vertical load, above branch force greater than the following branch. It is proposed recommended value about the vertical critical spacing of branch and the level spacing of pressured branch pile.
Studies on Geology of the Backfilling Fly Ash and the Foundation Treatments
Authors: Tian Jian , Xia Bao Shan , Wang Jin Di , Wei Tao
Published: May 2011

Whether the site of backfilling fly ash was appropriate for engineering geology, and how to use effective means to change the geologic bearing capacity of the site were urgent solving problems. This work took a site of backfilling fly ash in the Beishiwang Village, Yindu District, Anyang City, Henan Province as object of study, detailedly did a complete geologic survey on it, got related data and made its engineering geologic assessment and according to the characteristics and requirements of construction projects, we select the most optimal treatment means of the foundation and adopt the most safe and economic perfusion pile with post-pressure grouting to strengthen this engineering foundation.
Rectangular Stress-Block Parameters for Bending Design of Reinforced UHTCC Beam
Authors: Zhang Xiu Fang , Xu Shi Lang
Published: May 2011

The full replacement of plain concrete with ultra-high toughness cementitious composite (UHTCC) in structural members can obtain the enhanced structural performance over traditional concrete structures because of its prominent advantages such as the markedly ductile deformation capacity after post-cracking and excellent damage tolerance ability. In the current article, aimed at setting up the theoretical formula for the practical use in the bending design of reinforced beam made of UHTCC, the equivalent parameters introduced in rectangular stress block approach are analytically determined. Two existing models in compression for UHTCC, i.e., bilinear model and parabolic line then horizontal line (nonlinear model) are adopted in the derivation of the equivalent parameters. By comparing moment-curvature curve obtained from the experiment with the calculated one, the nonlinear model is verified to be rational and could predict bending capacity with sufficient accuracy. Further comparison between moment-curvature curves calculated according to two compression models shows that the nonlinear model can give a bending response prediction with almost the same accuracy as the bilinear model. Finally, it is suggested that, in the case that nonlinear compression model is adopted for the compressive behavior in UHTCC, the equivalent parameters α=0.8 and β=1.0 could be used to estimate ultimate load bearing capacity of reinforced UHTCC beam.
Deformation Characteristics of High Slope of Cihaxia Hydropower Station
Authors: Song Yan Hui
Published: May 2011

The geological conditions of high slope is detailed, the main deformation characteristics of high slope are described. Based on the above, it is known that the rock mass unloading-loosing and toppling deformation accompanying the creeping along bedding plane or fault mainly happen in the upper and middle portion of the high slope, especially in the upper portion. These deformations have other features in the middle portion of the slope: the deformed rock mass rarely appears the bending, but exists an obvious weak plane out of which the rock stratum and tensile fissures mostly dip to the inner of the slope, suggesting the deformation mainly is toppling and tensile-cracking; inside of the weak plane the dip direction is opposite to the outside. The deformation of the upper portion is different from the middle one in which there has a lot of tensile fissures which attitudes are variable and the degree of the breaking and loosing is largely higher than the middle portion of the high slope.
In Situ Test Research for the Affect of Surface Water Seepage on the Ground Fissures Action
Authors: Li Xin Sheng , Liu Chao , Wang Li , Xu Tian Zhu , Meng Hua Jun , Meng Fan Yu , Shang Jin Yu , Wan Tong
Published: May 2011

An in-situ water injection test across Xi’ an ground fissures has been done, in order to simulate the activity of the fissures after water seeps, from October to December, 2005. According to the settlement observed of the bottom of testing pit, it is proven that the surface water seepage speeds the movement of ground fissures. Usually, the soil on the hanging wall of the fissures is more fragmentized than that on the footwall, which is propitious to water seepage. The seepage promotes the interaction between water and soil particles and brings about the differential settlement of two sides of fissures. Therefore, surface water seepage accelerates the activity of the ground fissures.
Model Testing Research on Reducing Water Content of Saturated Over-Wet Soil
Authors: Hu Qi Jun , Wen Hua , Gong Cheng
Published: May 2011

This paper verified effect and feasibility by indoor model test of using drainage of vacuum preloading method and electro-osmosis method to reduce water content of saturated over-wet soil in moist and rainy areas. The results showed that: both methods could effectively reduce water content of saturated over-wet soil in Ya’an area, to achieve the desired effect of drainage and consolidation. Neither spatial distribution of level of reducing water content was obvious.
Field Test Study on Dynamic Stress Characteristics of Sand Soil
Authors: Song Xiu Guang , Yao Kai , Dou Zhi Gang , Yang Yang
Published: May 2011

In order to understand the dynamic stress diffusion rule of the waste iron slag (sand soil) during dynamic consolidation, we conducted a large field test. The propagation and attenuation of dynamic stress in each ramming strike was recorded through the resistance strain gauge. It was shown that the dynamic stress caused by dynamic consolidation is pretty obvious. The dynamic stress dissipates extremely fast during the dynamic consolidation, the time is only 0.5s after plus the aftermath. The soil dynamic stress has heart-shaped distribution during the compaction. The dynamic stress value increases with the tamping hit number, but it keeps stable after about the third hits.
Optimization Study on the Effect of Bolt Anchorage on Slope Stability by FEM
Authors: Weng Xiao Lin , Liu Bao Jian
Published: May 2011

This paper presents the calculation optimization for two examples of anchored slope, in respect of structural plane involved failures and circular slides by finite element method (FEM). A Goodman contact element subprogram was independently developed and nested in the finite element analysis (FEA) to determine the optimum anchorage parameters such as the length of the rock bolts and the angle at which they are installed.
Field Test on the New Method of Vacuum Dewatering with Lower-energy Dynamic Consolidation for Silty Soil Ground
Authors: Zhang Hong Bo , Song Xiu Guang , Wang Hong Hong , Ma Zheng
Published: May 2011

The dynamic consolidation method has been used widely in various engineering domain. With this method, the velocity of reconsolidation settlement was enhanced, the consolidation result was good, and the cost was lower than other methods. However, in the flooded area of Yellow River, the groundwater level is higher, and the shallow saturated silty soil liquefaction will be happened with this single method of dynamic consolidation. It goes against the roadbed stability. According to engineering practice, the vacuum dewatering with lower energy dynamic consolidation method was proposed in this paper. In order to monitor the effect of this consolidation method, the water-level observation hole, pore water pressure gauge, standard guide pile, level gauge have been set up. They could be used to get the groundwater level, the excess pore water pressure, horizontal displacement and land subsidence, respectively. These monitors would last the whole period of the consolidation experiment. Field test results shows that the excess pore water pressure was reduced by 80%-90% during one to three days.
Potential Slip Surfaces of Slope with Strength Parameters
Authors: Lin Hang , Cao Ping
Published: May 2011

The cohesion c and friction angle φ are the main strength parameters influencing the stability of slope. Any of them changes, the factor of safety of slope will change, but it has seldom been considered in the literature how the potential slip surface will change at the same time. In the present paper, the analytical deduction and numerical analysis are done to find out the effect of shear strength parameters c and φ to the distribution of potential slip surface. The study shows that, the potential slip surface is affected by the combination of c and φ, whose function is λ=c/(γhtanφ).
Parameter Inversion of Return Mapping Algorithm in Tunnel Engineering
Authors: Yu De Hai , Jiang An Nan , Wang Jun Xiang
Published: May 2011

The self-developed finite element program on return mapping algorithm is used to the simulation of the true tunnel with C + + language, while the finite element program is embedded into differential evolution algorithm to achieve the inversion parameter. Applying to Line 1 of Dalian Metro, rock mechanics inversion parameters and true parameters are close, which indicates the superiority and good prospects of return mapping algorithm and different evolution algorithm, and it can be used for quantitative analysis of actual tunnel.
Mechanical Analysis of Tunnel Crossing Ground Fissure
Authors: Li Kai Ling , Liu Hong Jia , Liu Yang
Published: May 2011

Ground fissures is one of typical geo-hazards in Xi’an area, which may cause damage of various types of buildings, city lifeline projects and resources, especially endangering the construction and running of Xi’an Subway. Ground fissures in Xi’an were introduced firstly, and models of land deformations and section destroy were found around Xi’an subway. Secondly, based on the interface mechanics, mechanical characteristics of interface between stratum on fissure and metro tunnel are studied, and void underneath metro tunnel are analyzed emphatically. At last, the result of numerical simulation shows that distribution law and amount of frictional force, scale and location of void under the tunnel, influence deformation and stress of tunnel; and then it also provides a theory basis for effective forecast evolution process of void underneath.
The Simulation Analysis on Vibration of a Museum Building Nearby Induced by Urban Subway Transit
Authors: Shi Lian Xu , Zhang Nan
Published: May 2011

The museum is adjacent to a subway tunnel, cultural relics may be damaged by the vibration induced by subway transit, so the vibration influence of museum must be strictly controlled. By building the three-dimensional finite element model which contains floating slab and isolation ditch, the calculation and analysis for each layer vibration acceleration value of the museum caused by the subway will be done. The results of the study indicate that vibration acceleration value were not more than vibration control limits, vibration reduction and isolation reach the predetermined purpose.
Experimental Research on Setting Stiffening Rib of Corner Joints in Gabled Frames
Authors: Wang Yu , Liu Yong Jun , Li Hao Bang
Published: May 2011

In order to clear constructional design of corner joint, it is necessary to further investigate mechanical property of corner joint in gabled frames. Through static test of comparing the panel zone with and without inclined stiffener. Some conclusions are given in the article. The load displacement curves show that the capacity of oblique nodes installed within stiffening rib components is enhanced i.e.40% more than those without stiffening rib nodes. The results reveal that in the gabled frames, the corner node with the inclined stiffening rib can improve the bearing capacity of the specimens. When the extraterritorial flange is tension, the erection of the inclined stiffening rib can prevent structural failure and improve effectually the ductility of the structure.
Analysis on Mechanical Properties of Tunnel Lining on Fire
Authors: Wang Wei Min
Published: May 2011

The paper analyzes the fire-resistant performance of big tunnel structure by setting up the analyzing model of tunnel-surrounding, choosing the characteristics of concrete, according to the lengthways and crosswise temperature distribution in specific scene of fire, analyzing the temperature and stress field of the tunnel structure, and knowing the basic rules and the damage of the lining and inner equipment of the tunnel by high temperature which is set on the Shanghai Yangtze tunnel. Tunnel lining is made up of reinforced concrete duct pieces. Concrete is a kind of non-homogeneous composite material, which would experience complex changing both physically and chemically by the high temperature, and the changing will surely lead to the descent of the carrying capability of the integral mechanical properties. The thesis studies the basic rules of the tunnel on fire and the damage of the tunnel lining structure and the inner equipments by the high temperature, which is set in the Yangtze River Tunnel in Shanghai, thus contributes to analyze the demand of the joint action of the disaster prevention, the ventilation system and other equipment and to reduce the fire loss.
Experimental Study of Environmental Noise from Metro Train
Authors: Li Dan Tao , Cao Guang Zhong , Qiu Hong
Published: May 2011

In order to study noise emitted by metro train, the experiment is carried out in the test line of Shenzhen Metro Line 1. It can be concluded that the noise outside the metro train is mainly middle and low frequency; the higher the train speed is, the larger the noise is; In static condition, the higher the measuring point is, the larger the noise is while in constant speed condition the higher the measuring point is, the smaller the noise is.
Moving Model Test of Express Container Car Passing through a Tunnel
Authors: Gao Guang Jun , Wang Xiao Ya , Zhang Lei , Jin Qi
Published: May 2011

This paper describes the moving scaled-model test of express container car passing through a tunnel on moving model rig where its scale is 1/17.6 and the length of the tunnel is 888.8m and the section area of the tunnel is 80 square meter and the interval of two truck is 4.4m in full-scaled model. The tests include that the container car passing though a tunnel with its speed are 120, 140,160 and 176km/h separately and its lowest Renolds number. The results show that the figure of the pressure wave on the car body is almost the same when train is in tunnel with different speed and that the amplitude of the pressure wave is proportion to the square of the train speed. The pressure on the car is always negative when train is in tunnel while the pressure on the wall of tunnel alternate between positive and negative. The coefficient of pressure wave on the car body is -0.7 and the peak values of pressure coefficient of point on tunnel are 0.6 and -0.7. The amplitude of the pressure wave on the car decreases according to logarithmic law nearly. The amplitude of the micro pressure wave is proportion to the cubic of the car speed.
The Research of the Spectral Features of Vibration Signals from Underground Railway Based on Wavelet Transform
Authors: Yin Zhi Gang
Published: May 2011

Using wavelet transform, signal’s frequency properties of vibration induced by underground are analyzed A MATLAB program is developed in order to decompose and reconstruct acceleration signals. The law that acceleration signals change in time-spectral domain is got. Then the relations of vibration signal’s maximum acceleration, energy, frequency and spectral are discussed. In contrast to conventional Fourier Transform， wavelet analysis can provide the evolution of spectral features of a signal as this evolves in time. It is ideal for random and non-stationary signal analysis.
Study on the Construction Mechanic Behaviors of Different Cross-Section Shape Connected Aisle in the Shield Tunnel with High Hydraulic Pressure
Authors: Wang Shi Min , He Chuan , Liu Si Jin , Lan Lei Lei
Published: May 2011

With the construction of large quantities of shield tunnels, based on the consideration of the performance, disaster prevention, relief and tunnel drainage requirement, it becomes more and more important to set the connected aisle in the shield tunnel section. The shape of the connected aisle cross-section has an obvious effect on the deformation and stress of the connected aisle. In order to draw reasonable connected aisle type for the subway construction under high hydraulic conditions, the comparative analysis of stress state of the circular and horseshoe-shaped connected aisle section is applied based on the construction of the connected aisle in the shield tunnel across the Yangtze River in Wuhan subway. It is recommended that the horseshoe-shaped cross-section should be applied to connected aisle construction in the shield tunnel in Wuhan subway.
Reliability Analysis of Beam String Structure Considering the Failure of Key Components
Authors: Liu Zhan Sheng , Xu Rui Long
Published: May 2011

There have been few researches on the reliability of prestressed steel structure, especially the study on the reliability considering the failure of key components. In order to study the impact of the component failure on the structure reliability, the response surface method based on central composite design is adopted and APDL language is applied to write a corresponding program, thereby carrying out reliability calculation and analysis to the model. The system reliability and parameters sensitivity of the beam string structure under different failure of components are provided. The results indicate that the impact of cable failure on the reliability is large, but it is weak by the failure of brace rod. The results may serve as a reference for the health monitoring and safety assessment of the prestressed steel structure.
Effect of Structural Stiffness on the Microvibration Response of the Working Platform of a Microelectronic Plant
Authors: Yuan Wei Ning , Qu Shang Wen , Lei Zi Xue
Published: May 2011

Microvibration is one of the key factors affecting the normal operation of a microelectronic plant. Such measures as to increase the stiffness or damping ratio to prevent microvibration are easy to implement and low in cost. By using the finite element analysis software Sap2000 to simulate the microvibration performance of the working platform of a typical microelectronic plant, this paper compared some of its microvibration response when there were shear walls with that when there were no shear walls, discussed efficiency of structural stiffness on its microvibration response. The results indicate through the provision of shear walls to increase the stiffness of working platform enlarge acceleration and velocity response of the structure, it can decrease displacement effect.
The Interaction Mechanism of Surrounding Rock and Supporting Structure in High Geostress Extrusion Fault
Authors: Chen Zhi Min , Zhao De An , Yu Yun Yan
Published: May 2011

Muzhailing tunnel of Lanyu railway is located in the western part of Qinling Mountain, its geological conditions are very complex. There is an extrusion fault, f16, in the Dazhangou inclined shaft, and the strata are consist of slate, sandston and carbonaceous slate. The measured geostress results showed that this location is in a very high level of geostress state, the maximum horizontal principal geostress is nearly vertical to Dazhangou inclined shaft and the measured horizontal lateral pressure coefficient is 3.79. Soft rock crushing, high geostress state, high horizontal lateral pressure coefficient and other factors led to the poor stability for the shaft. During the construction process of the shaft, the deformation characteristics are showed as strong horizontal deformation, rapid and large rate initial deformation, and long duration. According to rock lithology conditions, geostress conditions, supporting structure and dynamic construction, deformation characteristics of the shaft, the large horizontal deformation was caused by the interaction of high horizontal lateral pressure coefficient and poor geological conditions and other factors, but the main reasons of the large horizontal deformation were recognized as uneven vertical and horizontal load, extreme adverse load conditions of support structure, based on the theoretical and 3D numerical analysis. Through the analysis of the interaction of support structure and the surrounding rock, the smaller deformation in front of the working face during tunnel excavation is took place, the less stress release would be took place and the larger the ultimate load would be on the support structure. Tremendous stress was withstood by the arch crown, larger wall tensile stress was appeared at side wall, the support structure is in a poor stress state. This paper provides a theoretical basis for dynamic design and construction of the Dazhangou inclined shaft and Muzhailing tunnel.
Optimization Analysis of Shallow Tunnel Excavation
Authors: Zhao Yao Qiang , Li Yuan Hai , Liu Qing Fang
Published: May 2011

In this paper, FLAC3D, the general software for geotechnical engineering project, is used to conduct two-dimensional numerical simulation for typical shallow tunnel excavation methods which include full-section method, the upper and lower step method, three-step method and CRD method etc.Effects of different excavation methods to the stability of tunnel surrounding rock are analyzed. The paper selected a subsistent tunnel as the research object. With construction simulation of different excavation methods, the paper makes comparative analysis of laws and characteristics of displacement of tunnel surrounding rock , stress distribution and size of plastic zones under different excavation methods. Study shows that: Ι.Followed by two step method, CRD engineering method and the full-section method successively, the three-step method is the best in the aspect of control of surrounding rock stress,; ΙΙ. Followed by full-section method, two- step method and the three step method successively, CRD engineering method is the best,in the aspect of size of plastic zones; Ш. Followed by three-step method, two-step method and the full-section method, CRD construction is the best in the aspect of control of surrounding rock displacement.
Numerical Simulation Analysis on Impact of Surface Deformation to the Frame-Shear Wall Structure Caused by Tunnel Excavation
Authors: Yuan Chang Feng , Yu Guang Ming , Zhao Qian Qian , Zou Jing Bo , Guan Xiao Ming
Published: May 2011

Underground engineering construction in the city can not avoid bringing about perturbation on the surrounding rock and soil and then endanger the adjacent buildings’ safety. This paper fixes the data of the ground settlement and moving calculation parameters by doing a back analysis of monitoring data which comes from ground settlement caused by subsurface excavation and combing with other engineering experience. This paper predicts the ground settlement，horizontal moving，horizontal deformation and the distortion of incline and curvatural by using the probability integral method.With the numerical simulation,the paper obtains the displacement, axial strain and structural moment’s deformation law which caused by the frame structure’s settlement.The result will provide technical support for the disaster prevention and reduction of underground engineering.
Effect of the Ratio of CODCr to Total Nitrogen on Enhanced Treatment of Sewage from Discharging Points of Rivers by Enzyme-Biofilm Process
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 promotion effect of enzyme on treatment of sewage by biofilm process, and investigated the effect of the ratio of CODCr to total nitrogen (C/N) on removals of pollution indexes. The research results indicated that with the decrease of C/N, the removal rates of CODCrwere stable and the removal rates of NH3-N increased, but the removal rates of TN obviously decreased in the three reactors. When C/N=5, the average removal rate of TN was higher than 30% in reactor B and C. When C/N=3, it decreased and maintained about 30%. When C/N=2, it was low and approximately 20%. When C/N=5, 3 or 2，the removal rates of CODCr, NH3-N and TN greatly increased in reactor B and C than in reactor A, which indicated that the promotion effects of the composite enzyme and the compounded enzyme on the removals of the target pollutants were favorable.
Seismic Behavior and Bearing Capacity Calculation of the Three-Layer-Closed-Restraining Stirrups Coupling Beam with Small Span-to-Depth
Authors: Liang Xing Wen , Che Jia Ling , Deng Ming Ke
Published: May 2011

Seismic behaviors of the nine coupling beam specimens that three-layer-closed-restraining stirrups arranged in the coupling beam section depth direction were investigated experimentally. Effects of span-to-depth, amount of stirrups and longitudinal bars of coupling beam on its failure mode are studied, as well as the hysteretic behavior, stiffness degradation, and deformation capacity. Coupling beams with span-to-depth ratio of 0.75－1.5 were observed to suffer shear failure or flexural-shear failure, no matter whether longitudinal reinforcements yield or not. The existing of three-layer-closed-restraining stirrups along the section depth of coupling beam effectively improved its deformation and energy dissipation capacity. According to the experimental results, the formulae for estimating shear strength of the coupling beams were suggested considering the effect of longitudinal reinforcements. Estimated shear strength of coupling beams agreed well with the experimental data.
Dynamic Reliability-Based Seismic Optimal Design of Base-Isolated Structures
Authors: Huang Tian Li , Ren Wei Xin
Published: May 2011

This paper presents a dynamic reliability-based optimization technique for the seismic design of base-isolated structures. Firstly, the governing equation of multi-degree-of-freedom base-isolated structures is established. Then, the superstructure is unfolded by the first mode. Considering that the damping is non-classical and the total base-isolation 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 superstructure with base- isolated system and the fixed-base structure as the optimal objective function, the dynamic reliability of the isolated system displacement as the constraint, the optimal design parameters of the isolated system are obtained through the penalty function method. A 3-story building with isolated 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 base-isolated structures.
Optimization Design of Steel-Concrete Composite Beams Considering Bond-Slip Effect
Authors: Zheng Shan Suo , Lou Huan Juan , Li Lei , Li Zhi Qiang , Wang Wei
Published: May 2011

The optimization methodology of the steel-concrete composite beam was proposed in this paper. The objective function is the cost of the composite beams, and the design variables are the geometry parameters, including height and width of the concrete deck, as well as thickness of the steel flange and web. The constraint conditions are main requirements stated in Chinese code for the design of composite beam, reasonable calculating theories and indispensable constructions, as well as some mature and consistent conclusions confirmed by experimental studies. Stiffness reduction coefficient is used to consider the effect of bond-slip effect between concrete and steel when calculating the beam deformation. The optimization for composite beam under uniform loads is given as a demonstration example finally. The methodology proposed in this paper should be useful for obtaining the solution of this kind of optimization problem.
3D Numerical Analysis of Seismic Performances of Dyke on Liquefiable Soils
Authors: Wang Ming Wu , Chen Guang Yi
Published: May 2011

Many field investigations of earthquake disaster cases confirm that earthquake-induced liquefaction is a main factor resulting in large damages to dyke. Consequently to ensure seismic safety of dyke on the liquefiable foundation, the research on seismic performances of dyke is of great importance. Herein seismic responses of dyke on the liquefiable soils were discussed by means of three dimension effective stress analysis method using a multiple shear mechanism model and liquefaction front. Two numerical models, in which the liquefiable foundation both consisted of saturated fine silica sand of 30% relative density and scenario waves with peak amplitude of 0.8056 and 3.133 m/s2 were used input waves, were conducted to investigate the distribution principles and the changing rules of deformation, acceleration, express pore water pressure, and shear dilatancy behavior in the dyke and the liquefiable foundation. The computed results do good agreements with the measured results from centrifuge tests. And these results may be of theoretical and realistic significance for seismic design of dyke on liquefiable soils.
Analysis of Permanent Deformation Scale of the Overlying Soil Caused by Earthquake Fault
Authors: Zhao Lei , Wang Jin Hua , Zhao Ji Sheng
Published: May 2011

Characteristics of the permanent deformation and surface rupture caused by fault dislocation in 512 Wenchuan earthquake are analyzed in this paper. On the basis of the data from surveying reports and engineering geological reports of some observation station, three kinds of overlying soil model are established and analyzed, the physical parameters coming from clay and sand: thickness 30m and 50m model of the clay, thickness 30m model of the sand and thickness 50m model of the clay containing sand interlayer. Results show: The thickness of the overlying soil is same, but fault dislocation changed, the permanent deformation scale of overlying soil with velocity of shear wave from 250m/s to 500m/s is almost same, but the surface rupture zone is different: shear wave velocity of the soil is low, surface rupture zone becme wide. With thickness of the soil increassing, the rupture zone become wide too. Influence of sand interlayer is small. Considering the setback distance determination, the geometric and kinetic characteristics of faults, regional seismic activity, material properties and thickness of the overlying soil are key factors.
Analysis of Linear Viscous Damper Parameters and Shock Absorption for Long-Span Cable-Stayed Bridge
Authors: Jia Hong Yu , Zheng Shi Xiong , Xia Ming Qiang , Yang Lei
Published: May 2011

The seismic behavior study of Fengdu Bridge will be conducted on a parameter of damping coefficient C of linear viscous dampers through linear dynamic time-history analysis. Simultaneously, the results are compared with the seismic response without viscous dampers. The parameter sensitivity study indicates that setting damper in longitudinal direction of bridge can reduce the relative displacement of key positions and the response of the bridge, the beneficial effect of the isolation in the longitudinal direction, but important amplification occurs in the vertical direction for relatively high frequency components. Moreover, the reference of application of linear viscous dampers will be provided for similar projects.
Earthquake Responses for Non-Proportion Damping System Based on Clough-Penzien Three-Step Non-Stationary Seismic Random Model
Authors: Huang Dong Mei
Published: May 2011

The solution method for earthquake responses of non-proportion damping system based on Clough-Penzien three-step non-stationary seismic random model is investigated in this paper. Firstly, the unified motion equation of non-proportion damping system is set up and then decoupled by complex mode method. Secondly, the earthquake responses in time-frequency domain are calculated by taking Clough-Penzien three-step non-stationary seismic random model as excitation, which ground motion parameters consistent with that of design response spectrum in china seismic code, and then the non-stationary time-varying variance of earthquake responses can be obtained, subsequently, the variances of equivalent stationary responses are integraled in ground motion duration. At last, an example of base seismic-isolation system is given to show the application of the proposed method.