砂岩岩石力学参数各向异性研究

对胜利油田不同深度的四口井的砂岩岩芯进行了三轴压缩试验和动态岩石力学参数试验。根据获得的垂直地层方向和平行地层方向的试验数据,计算了各岩石力学参数的各向异性系数。通过分析围压以及深度对各向异性系数的影响,给出了砂岩峰值强度各项异性系数、静泊松比各向异性系数、纵波波速各向异性系数、纵横波速比和动泊松比各向异性系数与深度的拟合公式。发现峰值强度、纵波波速和纵横波速比的各向异性系数都随着深度的增加而减小,而泊松比各向异性系数随着深度的增加而增大。动、静弹性模量各向异性系数与深度相关性都很差,动弹性模量各向异性较弱,静弹性模量相对较强。     

岩体施工过程损伤演化预测的时变力学分析

由建立的岩体损伤本构模型，依据时变力学理论对岩体进行不同施工路径下的分步开挖计算，并对施工过程中各点损伤演化历程进行计算机仿真模拟，以预测后续开挖的损伤状态及寻求较优施工步序。理论及算例分析均表明：存在损伤演化时，不同施工步序下岩体终应力位移和损伤状态均不同，设计与施工应进行损伤演化的时变力学分析，以保证施工安全。     

Protein Mechanics: A New Frontier in Biomechanics

Proteins play essential roles in all aspects of cellular processes, such as biosynthesis, division, growth, motility, metabolism, signaling, and transmission of genetic information. Proteins, however, could deform under mechanical forces, thus altering their biological functions. Here we present protein deformation as a possible molecular basis for mechanosensing and mechanotransduction, elucidate the important features of protein mechanics including protein deformation mode and dynamics, illustrate how protein deformation could alter biological function, and describe the important roles of protein deformation in force-sensing, force transducing and mechanochemical coupling in cells. The experimental and modeling challenges in protein mechanics are discussed.     

新世纪力学与材料研讨会简讯

“新世纪力学与材料研讨会”于２００１年７月９～１２日在西安召开,且每两年召开一次．研讨会的目的是：（１）交流和促进力学和材料学科及在先进技术中应用．（２）加强国际间中国出身的学者间的合作．研讨会的语言采用中文,演讲人和讨论主持人来自世界各地,研讨会向一切有成就的学者和研究生开放．每个演讲人用一小时讲解题目的背景,当前的研究水平并进行讨论．演讲是非正式的,允许与会者即兴提问．会议自始至终还有许多非正式的活动．第一届研讨会由西安交通大学陈宜亨教授和普林斯顿大学锁志刚教授任主席;西安交通大学王铁军教授…     

Effect of Initial Wettability on Rock Mechanics and Oil Recovery: Comparative Study on Outcrop Chalks

Surfactant-alternating-gas (SAG) is a favored method of foam injection, in part because of excellent gas injectivity. However, liquid injectivity is usually very poor in SAG. We report a core-flood study of liquid injectivity under conditions like those near an injection well in SAG application in the field, i.e., after a prolonged period of gas injection following foam. We inject foam [gas (nitrogen) and surfactant solution] into a 17-cm-long Berea core at temperature of 90 °C with 40 bar back pressure. Pressure differences are measured and supplemented with CT scans to relate water saturation to mobilities. Liquid injectivity directly following foam is very poor. During prolonged gas injection following foam, a collapsed-foam region forms near the inlet and slowly propagates downstream, in which water saturation is reduced. This decline in liquid saturation reflects in part liquid evaporation, also pressure-driven flow and capillary effects on the core scale. In the collapsed-foam region, liquid mobility during subsequent liquid injection is much greater than downstream, and liquid sweeps the entire core cross section rather than a single finger. Mobility in the region of liquid fingering is insensitive to the quality of foam injected before gas and the duration of the period of gas injection. This implies that at the start of liquid injection in a SAG process in the field, there is a small region very near the well, crucial to injectivity, substantially different from that further out, and not described by current foam models. The results can guide the development of a model for liquid injectivity based on radial propagation of the various banks seen in the experiments.

     

力学的反演、反演的力学

１地震发生了,是怎么造成的？１９７６年７月２８日唐山发生了一次７．８级的大地震,在没有警告的情形下,一座工业大城市顷刻之间夷为平地,死亡人数超过２４万,成为２０世纪伤亡最重的一次自然灾害．全国为之震惊．华北地区的人民尤为惊慌,希望知道这个地区是否还有发大震（这时随后发过好几次五、六级的余震）的危险,下次将在何处发震,特别是北京发震的危险程度如何．既然地震是一个力学过程,这个问题对我们力学工作者是一个严肃的挑战．从力学问题来看,我们所知道的是地震时得到的记录,地震后的遗迹（见图１,图２）所想寻找的…     

Inception and Development of Nonlinear Mechanics as a New Research Field

International Applied Mechanics - The works done by Ì. M. Krylov and M. M. Bogolyubov at the Institute of Structural Mechanics of the Academy of Sciences of the Ukrainian SSR and underlying...     

深部软岩新型相似模拟材料的研制

在总结以往相似模拟材料特点的基础上,结合深部软岩强度、变形特征,本着相似材料组分简单、模型制作便捷等原则,研制了仅以河砂为骨料,松香酒精溶液为粘结剂的深部软岩新型相似模拟材料。通过对不同配比试样进行单、三轴压缩、巴西劈裂试验,获得了不同配比条件下该相似模拟材料的强度、变形、破坏特征。研究表明,通过简单的配比调配,该相似模拟材料可以较好地模拟深部大多类型的软岩,且具有组分简单、模型制作便捷、力学性能稳定、无毒无污染、价格低廉、一定程度上可重复利用等特点。     

A New Method for Establishing Pseudo Orthogonal Properties of Eigenfunction Expansion Form in Fracture Mechanics

A new and simple method is developed to establish the pseudo orthogonal properties (POP) of the eigenfunction expansion form (EEF) of crack-tip stress complex potential functions for cracked anisotropic and piezoelectric materials, respectively. Di?erent from previous research, the complex argument separation technique is not required so that cumbersome manipulations are avoided. Moreover, it is shown, di?erent from the previous research too, that the orthogonal …     

Constitutive Equations in Continuum Mechanics

One of the main research areas in continuum mechanics is constitutive equations. There is no generally accepted viewpoint on or method for this research. Several concepts have appeared, but further studies are still necessary. The paper elucidates some problems and viewpoints of such research     

Functional Concepts in Continuum Mechanics

This paper is an attempt to give a concise presentation of the main concepts of continuum mechanics and to show their articulation. Functional definitions have been favoured.The first section is devoted to a review of continuum mechanics.The second section deals with the mechanics of materials.Constitutive equations of the material are given first by equations of state and then by complementary equations written in order to fulfil the fundamental inequality concerning the production of entropy and the physical properties of the material (viscosity, plasticity, damage etc.).Section 3 gives the Lagrangian and the Hamiltonian formulations for a moving body. Section 4 is devoted to the motion of surfaces through which discontinuities appear, to show briefly two examples of application of the previous concepts. One can easily define the source of intrinsic inhomogeneity, of heat, of irreversible entropy on a surface of phase transition and also for a shockwave.SommarioIn questo lavoro si cerca di dare una presentazione concisa dei concetti fondamentali della meccanica dei continui e di mostrare le loro articolazioni,con particolare rilievo alle definizioni funzionali. La prima sezione è dedicata ad un esame generale introduttivo. La seconda alla meccanica dei materiali, le cui equazioni costitutive sono date come equazioni di stato e come equazioni complementari scritte al fine di soddisfare le diseguaglianze concernenti la produzionedi entropia e le proprietà fisiche dei materiali (qualiviscosità, plasticità, guasti...).La terza sezione dà le formulazioni Lagrangiana ed Hamiltoniana per il moto di un corpo.La quarta sezione è dedicata al moto di superfici di discontinuità per mostrare brevemente due esempi di applicazione dei concetti precedenti.Viene quindi definita la sorgente di disomogeneità intrinseca, di calore, di entropia irreversibile su di una superficie, di transizione di fase ed anche di un' onda d'urto.