岩体损伤力学研究进展     

唐辉明  孙成伟 《地质科技情报》1995,14(4):85-92

论述了岩体损伤力学在岩体力学中的地位，并从细观和宏观两个方面系统介绍了其最新研究进展；对岩体损伤力学研究中的几个重要问题提出了见解，认为分形几何是研究损伤的有效手段。  相似文献   

端承桩基础轴向地震反应分析     

刘宗贤  李玉亭 《华北地震科学》1995,13(4):35-40

本文对分层弹性地基中端承桩基础通过特性分析建立了合理的力学模型，通过动力分析，给出了端承桩基础轴向自振特性及在竖向地震载荷作用下强迫反应的解析解。文中的解析公式为分层弹性地基中的端承桩基础轴向动力反应分析提供了一种新的解析方法。  相似文献   

Source mechanisms and microfracturing during uniaxial cycling of rock   总被引：1，自引：0，他引：1  

C. H. Sondergeld  L. H. Estey 《Pure and Applied Geophysics》1982,120(1):151-166

Focal mechanisms for 116 acoustic emission events associated with uniaxial cyclic loading of Westerly granite have been investigated using P-wave first-motions. Polarities were observed at eight transducers positioned on the sample to provide good azimuthal coverage. The P-wave radiation patterns can be fit by a quadrupole source but not by a simple pure tensional source. The predominant orientations of the two nodal planes for the quadrupole fit were subparallel to and perpendicular to the ₁ direction. Events with close hypocenters, i.e., within a radius of 3 mm, display a remarkable similarity in focal mechanisms irrespective of the cycle or time within a cycle at which they occur. The polarity observations of 48 of 116 acoustic emission events could be fit with the simple quadrupole indicating that the microfracturing processes even in uniaxial compression often simplistically portrayed as propagating axial cracks are indeed quite complex.  相似文献   

Autosuspension and the energetics of two-phase flows: Reply to comments on ‘experimental test of autosuspension’ by J. B. Southard and M. E. Mackintosh     

Chris Paola  John B. Southard 《地球表面变化过程与地形》1983,8(3):273-279

The experimental programme of Southard and Mackintosh (1981) provides a definitive refutation of the autosuspension criterion as it was originally defined. A simple energy budget for dilute two-phase flow is derived from continuum theory of mixtures; it shows that Bagnold's criterion is based on an arbitrary comparison of two elements of the complete two-phase system. It is recommended that facile, ab hoc criteria for the behaviour of such complex flows be avoided in favour of analyses based on fundamental equations of motion.  相似文献   

Constitutive relations for fault slip and earthquake instabilities   总被引：1，自引：0，他引：1  

James R. Rice 《Pure and Applied Geophysics》1983,121(3):443-475

Constitutive relations for fault slip are described and adopted as a basis for analyzing slip motion and its instability in the form of earthquakes on crustal faults. The constitutive relations discussed include simple rate-independent slip-weakening models, in which shear strength degrades with ongoing slip to a residual frictional strength, and also more realistic but as yet less extensively applied slip-rate and surface-state-dependent relations. For the latter the state of the surface is characterized by one or more variables that evolve with ongoing slip, seeking values consistent with the current slip rate. Models of crustal faults range from simple, single-degree-of-freedom spring-slider systems to more complex continuous systems that incorporate nonuniform slip and locked patches on faults of depth-dependent constitutive properties within elastic lithospheric plates that may be coupled to a viscoelastic asthenosphere. Most progress for the rate and state-dependent constitutive relations is at present limited to single-degree-of-freedom systems. Results for stable and unstable slip with the various constitutive models are summarized. Instability conditions are compared for spatially uniform versus nonuniform slip, including the elastic — brittle crack limit of the nonuniform mode. Inferences of constitutive and fracture parameters are discussed, based on earthquake data for large ruptures that begin with slip at depth, concentrating stress on locked regions within a brittle upper crust. Results of nonlinear stability theory, including regimes of complex sustained stress and slip rate oscillations, are outlined for rate and state-dependent constitutive relations, and the manner in which these allow phenomena like time-dependent failure, restrengthening in nearly stationary contact, and weakening in rapidly accelerated slip, is discussed.  相似文献   

The stability of underground workings in the soft rocks of the Coal Measures   总被引：2，自引：1，他引：2  

A. H. Wilson 《Geotechnical and Geological Engineering》1983,1(2):91-187

Summary The characteristics of soft rocks typical of the British Coal Measures are defined and a series of working hypotheses are developed to provide improved design methods for underground roadway and face supports and pillars in coal mines. Proposed design equations are tested against case history data.  相似文献   

Triple approaches in the plane isosceles equal-mass three-body problem     

V. V. Orlov  A. V. Petrova  A. I. Martynova 《Astronomy Letters》2001,27(10):678-682

We analyze flyby-type triple approaches in the plane isosceles equal-mass three-body problem and in its vicinity. At the initial time, the central body lies on a straight line between the other two bodies. Triple approaches are described by two parameters: virial coefficient k and parameter $\mu = \dot r/\sqrt {\dot r^2 + \dot R^2 }$ , where $\dot r$ is the relative velocity of the extreme bodies and $\dot R$ is the velocity of the central body relative to the center of mass of the extreme bodies. The evolution of the triple system is traceable until the first turn or escape of the central body. The ejection length increases with closeness of the triple approach (parameter k). The longest ejections and escapes occur when the extreme bodies move apart with a low velocity at the time of triple approach. We determined the domain of escapes; it corresponds to close triple approaches (k>0.8) and to μ in the range ?0.2<μ<0.7. For small deviations from the isosceles problem, the evolution does not differ qualitatively from the isosceles case. The domain of escapes decreases with increasing deviations. In general, the ejection length increases for wide approaches and decreases for close approaches.  相似文献   

Collapse of caves at shallow depth in Gaziantep city center,Turkey: a case study     

Hanifi Canakci 《Environmental Geology》2007,53(4):915-922

This paper focuses on an investigation of the possible causes for the collapse of limestone caves in Gaziantep, Turkey. The city contains a lot of man-made caves, at a shallow depth, of various width and length. These caves were mainly excavated to provide work or storage space. As the city has been growing fast with increased population, many structures were constructed over these caves. Recently, two caves collapsed and five houses were damaged. These caves are all made of limestone and it was observed after the collapse that the limestone was saturated with water due to sewer pipe leakage and surface water. Tests were carried out on the limestone and it was determined that the compressive strength of limestone decreases by about 50% and the tensile strength decreased by about 80% when saturated with water. It was concluded that the reduced strength of the limestone combined with additional loads due to the factors mentioned above seem to be the main reason for these collapses.  相似文献   

土结构性的研究方法及现状   总被引：23，自引：2，他引：23       下载免费PDF全文

齐吉琳  谢定义  石玉成 《地震工程学报》2001,23(1):99-103

介绍了土结构性的概念和土结构性研究的意义。回顾了土结构性研究的历史。对土结构性的定量化研究方法进行了分类。在分析国内外研究现状的基础上，提出了土力学方法是进行土结构性定量化研究的最为现实和有效的方法。  相似文献   

浅析山区高等级公路中的边坡工程岩体   总被引：6，自引：1，他引：6  

晏鄂川  王晋等 《地球科学》2001,26(4):347-351

随着山区高等级公路建设的飞速发展，各类边坡工程岩体问题也日益增多。从卸荷岩体力学的基本观点入手，探讨了边坡工程岩体的变形破坏特性、稳定性评价方法以及开挖设计理论。研究表明，边坡工程岩体的变形破坏特性完全符合卸荷岩体力学行为，不同于常规的加载岩体行为；边坡工程岩体的稳定性分析计算中必须重视水力学因素和卸荷作用的影响，并得到了有意义的表达式；边坡工程岩体的开挖设计应在充分认识其工程力学性状的基础上，针对边坡岩体地质特性，结合已有各类稳定边坡的资料，进行既经济又可靠的优化设计。  相似文献