Analysis on Superstruct-foundation-soil Interaction on Karst Region

Karst region is a kind of complicated groundsill.To design tall-buildings built on karst subgrade,precise analyse result is needed.The method based on superstruct-foundation-soil interaction theory can precisely calculate the(internal) force of structural,foundation and groundsill.The method of finite element is an effective way to solve the problem.Finite element analys is software ANSYS is used to analyze superstruct-foundation-soil interaction on Karst Subgrade.Through comparing methods based on superstruct-foundation-soil interaction with traditional analysis method(in this condition,superstruct-foundation-soil interaction is not taken into account),the interactional effect to structure,foundation and rock are discussed.Through the analysis,several conclusion can be drawn as follows: The side stress of column is small for buildings on Karst region,but the side stress of corner columns is much larger than the others.The side stress of shear wall is great and the location of shear wall is significant for the interaction.Slab foundation is effective for Karst region,it plays a great role on interaction.     

复合土钉支护转角有利影响范围

基坑复合土钉墙转角处有明显的空间效应，受力变形较小，对支护结构有利，但不清楚转角定量的有利影响范围，目前设计中仍按照与基坑中部一样保守设计，为在此范围内降低土钉用量，避免保守设计，对水泥土搅拌桩复合土钉支护结构建立了全尺寸整体三维有限元模型，这种模型包含基坑的转角，能考虑基坑的空间效应，通过建立接触面单元，能考虑土体和搅拌桩、土体和土钉的相互作用，量化分析了基坑转角对支护结构受力和变形的有利影响范围，计算结果表明，基坑转角对开挖面水平位移、地表沉降、坑底隆起、土钉轴力的有利影响范围分别约为1.3、1、1、1.2倍的开挖深度。经与实际工程现场实测值对比，验证了该模型分析结果的可靠性，同时分析结果优于平面二维和局部三维有限元模型，结论为复合土钉支护结构的优化设计和安全施工提供了理论依据和研究方法。     

Elastic Analysis of Beam-Plate Foundation with Winkler Model

The beam-plate foundation is divided into two parts.The boundary element methods areapplied to analyze the plates with Winklermodel.The finite element methods are used to evaluate thebeams The coupling equation is obtained by the coodination of both force and displacement.     

Analysis on Deformation Characteristics of CFG Piles-Gravel Cushion Composite Foundation of the Deep Embedded Secret Passage

In order to investigate the issue in the field of the application of CFG pile application of CFG pile composite foundation technology in deep embedded secret passage of such special structure ground treatment, the settlement deformation of CFG pile composite foundation according to deep are studied and detailed analysis are given in the field test and indoor model test of the gravel cushion with different thickness. Moreover it points out that the cushion compressive deformation must be taken into account, and that the settlement deformation calculation cannot simply consider the amendments of composite foundation. The amendments of cushion deformation must be considered. The effect of the different thickness of cushion on pile-soil stress ratio, total settlement of composite foundation, cushion compression and axial stress of pile body were analysed by using ABAQUS finite element method. Through the analysis of the field test, indoor model test and the numerical simulation of CFG piles-gravel cushion composite foundation of the deep embedded secret passage, a settlement deformation monitoring method has been described and the selection principle of the cushion has determined so as to provide the cushion design basis in the process of composite foundation design.     

An Analysis of Thick Plates underIn-plane and Transversal Loadings by the BEM

In accordance with the behaviours of thick plates under the in-plane and transversal loadings,and introducing the concept of equivalent load, the coupled equations for the problem have been deduced with the theory of BEM in this paper.Thus a new method is presented for solving the problems of interaction of superstructure and foundation and subsoil,as well as for the problems of the thick plates under the complicated loadings.     

Boundaty Element Method for Analysis of Thick Plates on Two- Parameter Elastic Foundations

This paper discusses the Reissner's plates on elastic foundation.The elastic foundation is considered as two- paramerer and its effect to thick plates are taken into account by a set of govering differential equations. According to the foundamental solutions for bending problem on two- parameter foundation derived, three boundary integral equations denoted by generalized displacement functions are established. This method is suitable to solve the bending problem of thin or thick plates on two- parameter foundation with arbitary boundary condition, arbitary shape and arbitary load conditions     

THE METHOD AND ITS APPLICATION FOR COUPLED ANALYSING PLASTIC DEFORMATION OF ROLLING WORKPIECE AND ELASTIC DEFORMATION OF ROLLS

A method for coupled analysing plastic deformation of rolling workpiece and elastic de'formaticn of rolls is developed. The interaction of plastic defo rmation of rolling workpice and elastic deformation of rolls is considered. The couple is formulated by setting up force equilibrium equation at the interface of the rolling workpiece and tne rolls. The plastic deformation of rolling workpiece is treated by the rigid plastic finite element method and the elastic deformation of rolls is treated by the boundary element method. The rolling presure, perunit. forward slip, neutral from angle obtained from coupled analysis are lower than those obta-ined rigid rolls. The results obtained from analysis show that the analytical accuracy can be heightened using the coupled ana-ytical methcd dveeloped for treatng rolling3proccss.     

Earth Pressure on Retaining Structure of Round Deep Foundation Pit in Sand-cobble Soils

In recent years, the round deep foundation pits engineering gradually appears in Chengdu Plain whose strata are mainly sand-cobble soils. However, there are no proper calculation methods of earth pressure in retaining structure like this and distribution mode of the pressure is unknown. With the use of elastoplastic numerical simulation method involved in interaction between retaining piles and soil, the distribution law of earth pressure of the round deep foundation pit retaining structure is determined. The result shows that distribution of earth pressure on a pile is triangular and the maximum lies in the location of pit bottom, but the average value of the pressure is less than Rankine active earth pressure. Model tests have also been carried out so as to verify the distribution mode. As for the test model, the values obtained by the numerical simulation method are approximately similar to the experimental results in the distribution law as a whole, which to some degree suggests the rationality of the numerical simulation results.     

Influence of Pile-soil Dynamic Interaction for the Structure Elastio-plastic Deformation

It is necessary to analysis the structure elastoplastic deformation subjected to rare seismic action and the present methods are mostly based on the rigid foundation assumption, which give rise to the method considering the soilstructure dynamic interaction. Adopting the plan pile-soil-structure elastoplastic finite element models, the influence of soil- structure interaction for the structure elastoplastic deformation in the horizontal earthquake has been analyzed. Through analysing we found, considering interaction, the muhilayer-frame elastoplastic displacement was discounted, elastic displacement was minished in the weakness layer and the possibility of break was reduced. The elastoplastic deformation computed by the Code is conservative.     

FEM Analysis of Differential Settlement of Gravel Pile Foundation Under Large scale Oil Tank

In order to reduce the differential settlement of gravel pile foundation under large scale oil tank, axisymmetric numerical simulation method and finite element method was employed to study the pile length, the exchange rate of length, the length of the cushion course to the influence of differential settlement and the relationship of negative lateral displacement and the settlement. It is found that: differential settlement has a minimum range of pile length. For the oil tank foundation center, by keeping the pile diameter, increasing pile spacing can increase the rate of exchange and obtain smaller differential settlement in relatively smaller displacement rate conditions. And by keeping replacement rate unchanged, the larger the pile diameter(namely the looser pile spacing) is, the smaller the differences settlement of the gravel pile foundation is. Moreover, pile length adjustment and the exchange rate have obvious effects on different subsidence and not obvious effects on the length of the cushion course. The appearance of oil tank foundation negative lateral displacement is one of the most important features of differential settlement adjustment.     

BOUNDARY ELEMENT METHODS FOR PLATES ON TwO-PARAMETER ELASTIC FOUNDATION

In this paper,the boundary element methods are applied to analyse the plates ontwo-parameter elastic foundation according to two boundary integral equations.The bending mo-ment,torsion and shear force at any point of plates are discussed by means of the theory of elasticitymechanics.An example and a plate in practital engineering are analysed.The resulta show that thereare high efficiency,good accuracy and little storage with this method.     

Responses of Rubber Bearing Isolation Structure Considering Soil-Structure Dynamic Interaction

By means of the substructure approach in the frequency domain, equations of motion of the rubber - isolated structures are established considering the soil-structure dynamic interaction. The seismic responses of two shear-type base-isolated structures with an embedded rigid rectangular foundation are numerically simulated, and the influences of the different rigidities of soil on the effect of the base isolation and the seismic responses of the structure are investigated. It is concluded that rubber bearing isolation can reduce the dynamic characteristics of structures and reduce displacement of floor and basement relative to ground. Meanwhile, considering the dynamic soil-structure interaction may reduce the isolation effect of the rubber-isolated structures and the effect level is in direct proportion to the stiffness of the superstructure and inverse proportion to the stiffness of foundation soil.     

Numerical simulation of dynamic response and radiation noise of gearbox

Considering the internal dynamic excitation produced by stiffness excitation, error excitation and mesh impact excitation, a dynamic finite element model of transmission system and structure system of gearbox is established. The normal mode and the dynamic responses of gearbox under the internal dynamic excitation are calculated by using the numerical simulation software ANSYS. Based on the result of dynamic responses, the boundary excitation condition is determined, and then the acoustic boundary element model is built. With the software of SYSNOISE, the surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The test of airborne noise is carried out. The computational results obtained are in a good agreement with the data of experimental test.     

A New Coupling Analysis for Interaction of Space Frame- Foundation- Soil

The boundary element methods for raft foundstion are coupled with substructuring method of space frames. The mixed method is presented with force- displacement. and example is analysed and the result shows that the laws of interaction are confirmed, and that there are high efficiency and little storage with this method     

Dynamic Characteristics of Structure-Soil-Structure System for Two Neighbor Buildings

In order to realize the variation of structural dynamic characterics due to neighbor structures in buildings, the surface structure is idealized as an equivalent single degree of freedom system with rigid base whose site consists of a single homogeneous layer. The dynamic characteristics of three-dimensional structure-soil-structure interaction system, including two identical structures, are investigated to identify the additional effects caused by the presence of a second structure. When comparing the data from the soil-structure system with only one structure and the structure-soil-structure system, two close natural frequencies with opposite phase modes are identified. Therefore, the term twin-frequency is proposed. Next, the value of twin-frequency varying with the frequency ratio of structure to soil is discussed. Meanwhile, the relative distance between two structures and the ratio of foundation width to soil thickness are covered. The data will be used to consider the coupling effects of soil on the dynamic characteristics of structure-soil-structure systems. Finally, a numerical case of seismic response of the structure-soil-structure system is calculated under traveling wave excitations. The numerical results indicate that the twin-frequencies cause beatings of the structures as well as ground motion.     

Finite Element Method of 3D Stable Heat Conduction of Steel Fluid in Continuous Casting Moulds

The heat transfer of steel fluid in continuous casting mould is a stable process and can be depicted with three-dimensional stable heat conduction equation depending on tension speed. The corresponding finite element equation, including the first, second and third boundary conditions, is deduced out with Galerkin residual method. The coded FEM program is used to analyze the temperature distribution of Q235 steel in continuous billet casting mould. The method proposed is a foundation of thermo-mechanical coupled analysis for the formation of solidified shells and stress in the shells in continuous casting.     

Study on Analysis Methods for Rock Slope FoundationStability of the Highrise Building

Based on the practical project a study on analysis methods for rock slope foundation stability of highrise-building project criterion transfer coefficient method, rotation limit equilibrium method (Sweden slices method) and finite element method was carried out.The authors found that safety factor of criterion transfer coefficient method is larger than that of rotation limit equilibrium method, but is similar to the results of finite element method. So, when rockslope foundation stability of highrise building is to be analysed,the rotation limit equilibrium method is suggested to use.     

A Boundary Element Separation Solution to the Elastic Contact Problems and the Optimal Penalty Factor

In this paper the boundary element separation to the elastic contact problems proposed by Kamiya is improved. It gives another optimal penalty factor to accelerate the iteratively saluting procedure, which makes a theoretical foundation for the application of computers' parallel processing method to reduce the calculation time and memory. A practical example is given to confirm the validity of the present method in comparison with Kamiya method.     

Deflection and Stress Analysis of a Pavement Slab under Temperature Gradient and Axial Loading Coupling

It has been established that a pavement slab will curl up if a temperature gradient exists across the depth of a slab. A negative temperature gradient causes the slab edge to curl up while a positive temperature gradient curls up the slab center. Temperature stress in slabs is induced by self-weight and other slab constraints. At present in P. R. China, the total stress considered in cement concrete pavement design includes the load stress plus the temperature stress, and only transverse cracking from bottom to top is considered for concrete pavement. Slab responses under axial loads and temperature gradient coupling are not included. We modeled a single slab with a frictionless interface between the slab and foundation using the finite element method. Slab deflection and stress were calculated under axial loads at different slab positions and negative or positive temperature gradient coupling. The calculated results show that the different conditions of axial loads and temperature gradient coupling will change the maximum tension and cause various types of cracks in a slab.     

Preprocessor of Reinforced Concrete FEM Analysis

Reinforcing element and concrete element have effects on the order of the stiff-matrix of the reinforce-concrete FEM. The program divided the elements is programmed by FORTRAN language in current analysis, and the data of the elements are stored by the array. The stiff-matrix of the reinforce-concrete FEM is extended by the large residual between the serial numbers of the nodes of cohering element. This paper establishes the graph class, path class and point class via objectoriented programming. The storage of the points and the paths by the chain structure realization of copying graph, moving graph, adding graph, continuously numbering the cohering elements are built. This paper presents the example of the dividing domain with the crack.