Axial Response of Viscoelastic Pile-soil Coupling Interaction in Three-dimensional Inhomogeneous Soil

Considering the three-dimensional inhomogeneity of soil surrounding the pile, the response of non-uniform viscoelastic pile under axial dynamic loading is studied. Firstly, combining the boundary condition, the complex stiffness of axial different soil layers are obtained by the complex stiffness transfer model of radial multi-zone plane strain. Then, the analytical solution of dynamic response at pile top in frequency domain is proposed by solving the dynamic equation of non-uniform viscoelastic pile section one by one from the bottom up to the top, and the relevant semi-analytical solution response in time domain is adopted by the convolution theorem and the Inverse Fourier Transform. At last, the effect of parameters of pile and soil are investigated to get the nature of the dynamic response of pile top in frequency domain and time domain.     

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.     

COUPLING ANALYSIS METHOD FOR INTERACTION BETWEEN FOUNDATION WITH CAVERN AND FRAME STRUCTURE

In this paper,the interaction between foundation withcavern and frame structure is studied by the coupling methods of BEMand FEM.On the interface between the foundation and structure,thecoupling analysis needs to satisfy both the condition of displacementcompatibility and force equilibrum.A calculating program for two-dim-ensional problem is worked out in the computer,SIEMENS 7570C.Twoengineering examples are calculated and the results are compared withthose obtained by the comventional simplified method and with the observedresults from the engieering structures.It indicates that it is necessaryfor the weak rock foundation with shallow cavern,in the buried depth,to take the interaction into account.     

A Method Coupling FEM and Singular Solution of Infinite Plane with a Hole for Underground Engineering

In this paper, a simpler and direct coupling method, i.e. finite element method coupled with singular solution of infinite plane with a hole, is proposed for the analysis of underground engineering. The numerical example shows that the elastic effectiveness of the infinite plane outside the artificial boundary upon the inside region is exactly expressed.     

Ecological Coupling Theory and the Method System of Urban countryside Space Planning

Since P. R. China has experienced extensive land resource use, environmental degradation, lagging rural development and other difficulties in 20th century, urban countryside integration and ecological planning has become an important subject to build a harmonious society in the 21st century. The country attempted to use complexity science and ecological thinking based on recognizing the relationship between the city and countryside and raising the city countryside space ecology coupling concept to construct a city countryside space planning methods system consisting of the identification of urban and rural land uses, urban and rural non construction land planning, city countryside coupled environmental conditions assessment, coordinated city countryside space development and city countryside space system fractal optimization, and more.     

基于土壤微生物的碳氮互作效应综述

土壤微生物在养分循环中起着至关重要的作用,可为陆地生态系统能量流动提供动力。碳(C)、氮(N)元素是构成生物基本骨架和能量代谢最基本的元素,其循环关系到生物生长和生态系统的稳定性。在陆地生态系统中,土壤微生物C、N元素有着明显的相互作用,环境中C、N浓度的变化会促使其发生变化,进而导致微生物群落结构和生物功能改变。笔者从CO2浓度升高、黑碳添加和N沉降加剧出发,总结了环境条件变化对微生物C、N的影响;分析了现实环境背景下土壤微生物C、N的相互作用,探讨微生物C、N的内在联系,为微生物C、N耦合及生态系统C、N耦合提供参考依据。并提出,今后在气候变化对土壤微生物影响的研究中,应当根据地域和时空的差异建立多个研究模型,深入研究微生物C、N与环境中C、N的关系,注重生态系统C、N耦合的同时,也要注重微生物与其他生物之间,特别是与植物之间的C、N耦合。     

A New Spline Boundary Element Method

This paper introduces a New Spline Boundary Element Method, which neither has corner problems and singular integrals nor involves extreme-conditions of spline function. Three numerical examples are given to show the validity of the method.     

Calibration of Nonlinear Dynamical Analysis for RC Frame-wall Structure with Slender Coupling Beams Considering Stiffness Reduction

Two 16-storey frame-wall structures with slender coupling beams in regions of Intensity 8(0.2 g),with and without considering the stiffness reduction of the coupling beams,were designed.Nonlinear dynamic response analyses of two typical frame-wall structures subjected to several ground motions were carried out.The analyses were based on the quasi-tridimensional program for nonlinear dynamic response analysis TS-EPA.The analyses led to the following conclusions: Under rare earthquake actions,the coupling beams in framewall structures yield first.This shows that the coupling beam in frame-wall structures is the member at the forefront of earthquake resistance.Comparison of the analytic results of two couples with and without considering the stiffness reduction of the coupling beam found that,in view of the dynamic response to and the requirement for ductility under rare earthquake motions,reducing stiffness causes a minor unfavorable influence on the dynamic response of frame-wall structures.     

A New Method for Analysis of Interaction of Rock Mass with Multiple Cracks under Seepage Pressure

According to the theory of fracture mechanics, the mechanical model of rock-mass with multi-cracks under the action of seepage pressure was set up. Based on the principle of superposition, the formula for calculating stress intensity factor (SIF) was built. The stress intensity factor of cracks in different conditions, such as different crack distance, different crack angle and different seepage pressure, were discussed. It is suggested that, if distance between two cracks is short, the interaction of cracks has significant influence on stress field of crack tip. According to the change of relative crack location and crack angle, the different superposed stress can produce two effects, stress field strengthen and stress field weaken. The stress intensity factor would be increased when the crack tip is in the stress strengthen area; otherwise this value would be decreased. The interaction of adjacent cracks is related to the distance between two cracks. As the crack distance increases, the SIF is close to a fixed value which is calculated without considering the interaction between cracks. Therefore, when the crack spacing is larger than crack length, the interaction between adjacent cracks can be ignored. The results also show that the seepage pressure significantly affects the stress field near crack tip, and the stress intensity factor KI increases along with the increase of seepage pressure (-KI decreases).     

Finite Element Simulate Analysis of Small Span-to Depth Ratio Coupling Beams with Special Reiforcement

Test investigations show that the reinforcement scheme with adding diagonal and rhombic bars to traditional reinforcement in the foundation is an ideal way, for the seismic performance of small span-to depth ratio coupling beams with this scheme is better than that of traditional reinforcement. Because the regions in the small aspect ratio coupling beam belong to D-regions, in which the Bernoulli hypothesis of plane strain distribution is invalid, the traditional bending theory can not be used. This paper simulates the coupling beam through non-linear finite element analysis program, and contrasts the analysis result of the bar's stress distribution with test result. The contrast results confirm that it is a valid way to analyse the bar's stress distribution in this coupling beam through non-linear finite element analysis program.     

A Three Dimensional Simplified Method for Analysis of Soil Arching Effect in the Pile-supported Embankments

To improve the understanding of the soil aching effect in the embankment fill, a series of model tests and finite element analysis were carried out. It is found that for low fill height relative to the net pile spacing, H/s－a≤1, the failure surface is vertical or slightly inclined which starts from the pile edge and goes through the whole fill height. For H/s－a≥1.5, the developed bulb shaped rupture surface is located near the pile head and can be approximated as a logarithmic spiral surface. By using the failure surface shape determined from the model test and FEM analyses, a three dimensional simplified method to evaluate the soil arching effect was proposed. The computed results were compared with FEM results and the experimental data collected from literatures, it is found that the present simplified method can predict reliable results.     

Coupling Effect Analysis Between Background and Resonant Components for Equivalent Static Wind Loadings

Aimed at the limitations of total fluctuating wind-induced response with combination of background and resonant components using Square Root of the Sum of Squares (SRSS) method, the theoretical combination formulas of fluctuating wind-induced responses and ESWLs are derived based on structural dynamics and random vibration theory. Meanwhile, the refined analysis method is firstly presented by four components formula to compensate the coupling component between background and resonant modes. The proposed procedure avoids the integration process of calculating elastic restoring force and completely considers the modal coupling effects, which can be used to calculate the ESWL for any complex structures. Taking the steel grid roof structure of a large museum as an example, the new method was used to calculate its wind-induced response. Compared with results of complete quadratic combination (CQC), the effectiveness and accuracy of the present approach has been revealed.     

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     

Analysis of Sun-shading for the External Public Space

In this paper,we summarize outdoor sun-shading forms in public spaces and compare the shading effects of several shading measures.Then,taking a public square in the city of Chongqing,P.R.China as an example,we analyze thermal environmental designs with full application of various sun-shading forms so as to give a reference for the design of future urban public spaces and the reconstruction of existing urban public spaces.     

Effects of the Adaptable Distribution for Lateral Forces Considering modes Coupling on Structural Pushover Analysis

Two high and flexible RC frame structures are analyzed;the paper explains the rise in the structural damping ratio and the base mode's drifting,and the modes coupling is caused by the greatly rising damping ratio.The paper also proposes that the modes coupling need be considered in the pushover analysis of the high and flexible RC frame structures.A CQC adaptive distribution for lateral forces in considering the modes coupling at every load step is given,and is compared with the traditional SRSS one.Meanwhile,some practical engineering suggestions are given.     

水肥耦合对紫色土中小麦肥料减施效应的影响

为了认识水肥耦合对紫色土中小麦的影响特征及肥料减施效应,在四川盐亭县青峰村和四川盐亭农田生态系统国家野外科学观测研究站的石灰性紫色土上,于2018年10月至2020年5月,用小区和盆栽试验等方法,观测不同水肥耦合处理对小麦和土壤主要属性的影响。结果表明,水肥耦合对小麦生长和籽粒产量有明显的促进效应,浇水到田间持水量的80%左右时,其促进效应最大;肥料用量减少10%～20%,不会造成小麦的明显减产;水肥耦合主要提高了土壤养分有效性和土壤酶的活性,因而有明显的促进效应。水肥耦合是紫色土区减肥增效的一种有效措施,从而能有效防治区域的面源污染。     

VBEM Analysis for Signorini Problem

the virtual boundary element method is applied for the numerical solution of a Signorini problem, which is conduced by an electro-paint process. The present method base on a switching algorithm, which can be applied to the problem defined in a non-regular domain, and it can reach good accuracy with less elements.     

A BOUNDARY ELEMENT METHOD FOR SOLVING DIRICHLET PROBLEM OF THE HELMHOLTZ EQUATION IN R~2

This paper presents a boundary element method for solving Dirichlet bou-ndary value problem of the Helmholtz equation in R~2.First,the existence andthe uniqueness of an extended solution for the problem are obtained.Then,thesolution is expressed in terms of simple layer potentials,and this expression,which is suitable to the interior as well as the exterior problem,leads to aboundary integral equation of the first kind.Finally,a finite element approachis applied to solve a variational form which is equivalent to the boundaryintegral equation.     

Suitability Analysis for System Planning of City Open Space

This paper introduced the suitability analysis method of landscape planning,and its application to the planning of open space system for Beihai City,Guangxi.Finally some problems for its application in practice and faculty for their solution were given.