应变能-莫尔准则及其在岩石材料中的应用     

卢万年 《地球科学与环境学报》1993,(2)

本文应用应变能密度与三向应力圆的等价关系,分析修正了莫尔准则,提出用任意确定静水压力下不同洛德参数的极限莫尔圆包络曲线簇作准则线,即谓之为应变能-莫尔准则线,并引用岩土真三轴试验资料进行验证;最后还得出应变能-莫尔屈服条件,分析了屈服曲面和屈服轨迹的形状等。  相似文献   

A novel analytical approach for predicting the noncylindrical pile penetration‐induced soil displacement in undrained soil by combining use of cavity expansion and strain path methods          下载免费PDF全文

Hang Zhou  Hanlong Liu  Jingrong Yuan 《国际地质力学数值与分析法杂志》2018,42(11):1270-1305

Since development of cavity expansion theory and strain path method, almost all the conventional analyses of pile penetration problem have been based on circular cross section penetrometer. However, noncylindrical pile (with noncircular cross section) is also required in geotechnical engineering such as rectangular cross‐sectional pile, X‐sectional cast‐in‐place concrete pile, H‐shaped steel pile, prefabricated vertical drains, and flat dilatometer. This paper presents a novel and general analytical approach for capturing the soil deformation mechanism around the pile with arbitrary cross section. The penetration problem is simulated by a new 2‐dimensional (radial and circumferential) cavity expansion model. Based on the theoretical framework of strain path method, the kinematics (velocity field) of the noncylindrical cavity expansion is reduced to solve the Laplace equation with arbitrary velocity boundary conditions by using the conformal mapping technique. Then, solutions for the strain and displacement, which could consider the large deformation effect, are obtained by the integration of the strain rate and velocity along the streamline. The analytical solution is validated by comparing the degenerate solution of this study with conventional circular (cylindrical) cavity expansion theory. Subsequently, typical numerical examples for the deformation mechanism of elliptical and rectangular cavity expansion are presented to prove the advantage of the proposed new solution particularly in capturing the noncylindrical symmetric displacement field. A brief application of the proposed new analytical solution to the interpretation of the smear effect of prefabricated vertical drain installation confirms its useful in geotechnical engineering.  相似文献   

Comparison of non-local and polar modelling of softening in hypoplasticity     

Th. Maier 《国际地质力学数值与分析法杂志》2004,28(3):251-268

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闽南丘陵区典型小流域空间框架数据采集与应用     

李新通 《福建地理》2007,(4)

综合利用Photoshop、Geoway、MapInfo、ArcView等软件提供的处理技术,通过对扫描得到的地形、土地利用和水土流失等要素图进行图像剪切、拼接、配准、采样、跟踪、调整以及属性表的维护等一系列处理步骤,建立了大比例尺小流域地理空间框架数据集,提供了小流域空间框架数据采集与应用的技术流程与方法,提出应用各种软件进行大比例尺空间框架数据处理过程中应当注意的各种细节问题.最后,以闽南丘陵地区草子坝小流域为例,利用ArcView的3D Analyst、Spatial Analyst、Geoprocessing等扩展模块以及MapInfo SQL查询功能,对流域空间框架数据进行处理,得到了用于比较精细空间尺度上表达流域三维地形模型、坡度、坡向、河流垂直剖面、晕渲,不同高程上的土地利用类型等专题应用结果.  相似文献   

Statistical analysis of the eigenspace components of the two-dimensional, symmetric rank-two strain rate tensor derived from the space geodetic measurements (ITRF92-ITRF2000 data sets) in central Mediterranean and Western Europe     

Jianqing Cai  Erik W. Grafarend 《Geophysical Journal International》2007,168(2):449-472

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Displacement fields and finite strains in a sandbox model simulating a fold-thrust-belt     

Faramarz Nilforoushan  Hemin A. Koyi 《Geophysical Journal International》2007,169(3):1341-1355

A sandbox model consisting of two adjacent mechanically different decollements (frictional and viscous) loosely simulated the southeastern part of the Zagros fold-thrust-belt. Digital images of the model surface are used to coordinate passive markers on the surface and quantify displacement fields and estimate 2-D finite strains. These analyses show that, mapped in a fixed coordinate system, the deformation front propagates at different rates above the two decollements. Strain analysis of the model surface at different stages of deformation also shows that cumulative strain is more heterogeneous above the viscous decollement where strain domains are separated by fault zones. Maps of displacement fields, finite strain ellipses and dilatation also differ in character above the two decollements. Displacements above a viscous decollement decrease gradually towards the foreland, whereas they decrease sharply in front of the frontal thrust above the frictional decollement. Our analyses also show that the estimated finite strain depends not only on the density of the marker points chosen for the analysis, but also their initial distribution relative to the structures. This comparison shows that marker density limits measuring the actual strains in a heterogeneously deforming fold-thrust-belt and marker density and distribution have a strong impact on the strain analysed in nature. The similarity of our model with nature is examined with recent GPS study in the Zagros fold-thrust-belt (SW Iran) and shows, similar to the model results, that a weak salt decollement causes divergent movement in the sedimentary cover in SE Zagros.  相似文献   

THE ENVIRONMENTAL VULNERABILITY OF CARIBBEAN ISLAND NATIONS*     

Bryan J. Boruff  Susan L. Cutter 《Geographical review》2007,97(1):24-45

ABSTRACT. Within the hazards‐ and disaster‐research community consensus exists as to factors that magnify or attenuate the effects of extreme natural events on local places. But less agreement and understanding exist concerning the methods or techniques for comparing hazard vulnerability within or between places, especially small‐island developing states. Using two Caribbean nations, Saint Vincent and Barbados, as study sites, we asked which island has the greater level of hazard vulnerability, and why. Results indicate that, although neither island has a large portion of its population living in extremely hazardous locations, Barbados has many more residents in risk‐prone areas. The methods used in this research provide valuable tools for local emergency managers in assessing vulnerability, especially through the delineation of highly vulnerable hot spots. They can also help donor organizations interested in vulnerability reduction on islands use their resources more efficiently.  相似文献   

单层褶皱变形过程中最大主应力与水平应变的变化及其影响因素     

周叶  林舸  龚发雄  刘士林  张德圣 《大地构造与成矿学》2007,31(1):37-43

对地质构造进行定量半定量研究是地质工作者近几十年来一直努力的方向,构造数值模拟是有效的定量研究方法之一。褶皱是一种典型的构造类型,对褶皱构造进行定量半定量研究也一直是构造地质学家们所致力解决的研究课题。本文结合近年来单层褶皱构造数值模拟研究进展,以及笔者近几年来对单层褶皱所进行的数值模拟实验研究,主要论述了单层褶皱变形的影响因素,单层褶皱变形过程中的最大主应力与水平应变的变化及其影响因素等。数值模拟技术为褶皱变形提供了一种新的研究方法,该方法在构造地质领域将有很好的发展前景。  相似文献   

Effect of cyclic loading on monotonic shear strength of fine-grained soils     

Ayfer Erken  B.M. Can Ulker 《Engineering Geology》2007,89(3-4):243-257

In this study the effect of cyclic loads on monotonic shear strength has been studied on torsional apparatus. Tests have been conducted on both reconstituted and undisturbed fine-grained hollow soil specimens. The plasticity index of soils is in the range from 2 to 33 for reconstituted specimens, prepared by dry pluviation, and from 5 to 13 for undisturbed soil specimens. The existence of a critical shear strain level, called yield shear strain, where softening starts, is determined from cyclic tests. The level of cyclic yield strain is ± 0.75% for the reconstituted soil specimens and ± 0.5% for the undisturbed soils. If soil undergoes a cyclic shear strain level below the cyclic yield strain, reduction of monotonic strength of reconstituted and undisturbed specimens is limited, but when cyclic shear strain level is larger than yield strain monotonic strength decreases down to 40% of its initial strength.  相似文献   

非局部本构的一种改造形式及内尺度分析     

赵纪生  陶夏新  欧进萍  师黎静 《岩土力学》2007,28(10):2036-2040

在Lagrange运动学描述的基础上,提出了一个普遍意义上的非局部效应本构关系的改造形式,它对每一个经过验证的本构都适用。这样处理既可以利用本构模型的研究成果,又计入了应变梯度对应力的贡献。以截面为单位尺寸正方形、无限长、小变形描述为例,讨论了理想弹塑性柱体内的P波行进特征,分析了梯度项、黏滞阻尼和滞变阻尼等效的材料内部尺寸效应。  相似文献