岩石力学前三章

1、1.1 Basic concept of rock mechanics Rock mechanics is a subject to study the mechanical behavior of rock or mass of rock which acts under the function of outside force, including stress state, strain state and failure criterion. It is a basic theory to resolve technical matters of engineering of roc

2、k.,Chapter 1 Introduction to Rock Mechanics,1.2 Rock mechanics cavalcade (history) Rock mechanics is a new branch of science which develops accompany of the building and progression of the mathematics, mechanics and rock engineering containing mining, civil engineering, water conservancy project and

3、 traffic. Its development could divide into four steps: (1) first time (end of nineteenth century till early of twentieth century) In this time primary theory appeared to solve the mechanics calculation of excavation of the rock mass.,(2) Empirical theory (twentieth century till thirty years) Lithos

4、tatic pressure theory地压理论appeared to analyse the supported problems of the underground excavation using mechanics of materials and structure mechanics according to production empiricism观察实验法 . (3) Classic theory (twentieth century thirty years till sixtieth years) Its an important stage for the form

5、 of the rock mechanics. In this stage elasticity and plasticity were introduced into rock mechanics, confirming a lot of classic equations and the function of surrounding rock and supporting rock. Structural plane was thought more of the infection in rock characters. Document and monograph was publi

6、shed.Test method was improved. Technical of engineering problem was solved.,In this stage rock mechanics had developed to be an independent subject. Continuous medium theory and geologic mechanics theory were founded. (4) Modern times (twentieth century sixty years till now) Its an important times f

7、or rock mechanics to develop in the field of theory and practice. Complicated mechanical model was used to solve the problem of rock mechanics.The latest results in fields of mechanics, physics, system engineering, modern mathematical statistics and information technology were introduced into rock m

8、echanics. Its possible for theory including rheology, fracture mechanics, discontinuum mechanics, numerical method, fuzzy(模糊) theory, artificial intelligence and nonlinear theory to be introduced in to rock mechanics and engineering as result of the development of technical of computer.,1.3 research

9、 content and method (1) research content geologic character of rock or mass of rock content： material component and structural feature； structural plane feature with its impact on mechanics characters of rock mass； structure of mass of rock and its mechanics characters； classification of rock mass e

10、ngineering.,physical characters, water physical property and thermodynamic behaviour of rock The physical characters of rock is a total of porosity, permeability, compressibility, electrical conductivity and heat transmissibility. Water physical property of rock is the character of rock interacting

11、with water,including. water absorbing quality, hydraulic permeability, dehardening quality and antifreezing quality.,fundamental mechanical property of rock content： deformation and strength feature and mechanics exponent parameter under any kinds of force； main factors impacting on rock mechanics c

12、haracters include condition of loading,temperature and humidity； rock deformation failure mechanism and failure criterion。,structural plane mechanics characters content： deformation characters and certain of parameters of structural plane under the compressive stress； shear strength feature and test

13、ing technique and methods of structural. distribution laws and measured theory and methods of in site stresses.,mechanics characters of rock mass content： deformation and strength feature and in-situ measurement technique and measures of rock mass ； weakness treatment and thumb rule of mechanics par

14、ameter of the rock mass ； main factors impact on rock mass ； occurrence and migration mechanism of underwater contained in rock mass and hydromechanics feature of rock mass.,stability of project body content： feature of distribution of stress and displacement under excavation loading in project body

15、； deformation failure feature of project body under excavation loading； stability analysis and evaluation of project body。 protection technique of rock stability including improvement of body characters and bonding,the use of all kinds of new technique 、methods and theory in rock mechanics. model 、

16、simulating experiment and in-situ detection technique of project body. Simulating experiment including numerical model simulating and physical model simulating is an important method to solve the rock mechanics and practical problems. In-situ detection technique could not only test the correction of

17、 analysis results of the body deformation and stability but also find question and take steps to solve in time.,(2) research methods Rock mechanics is an marginal intersectant subject whose research content is extensive and object is complexity which lead to multiformity of methods of the research o

18、f rock mechanics. The research of rock mechanics could be classified four methods according to research measure or basic theory: engineering geology research method scientific experiment method mathematics mechanics analysis method integral multidisciplinary analysis method, engineering geology rese

19、arch method This method emphasizes on the geologic characters relational mechanics characters of rock and body. For example, rock identification method can find out the style of rock 、mineral production component and structure feature; stratigraphic geology 、 structural geology and engineering explo

20、ration can find out the formation reason、distribution and structure plane; geohydrology can find out the formation and movement law of underwater in body., scientific experiment method Scientific experiment is the base of rock mechanics including measurement of laboratory rock mechanics parameter、mo

21、del experiment、in-situ experiment and detection technique 、measurement of stress and structure of body.The experiment result can offer the necessary physical mechanical parameters which is used in calculation of deformation and stability analysis. At the same time evaluation can be made directly on

22、deformation and stability of body so much as rock mechanical theory problem., mathematics mechanics analysis method Mathematics mechanics analysis is an important process in research of rock mechanics. It dope out the deformation and stability of body under kinds of fields of force based on mechanic

23、al model of project body and analysis methods to offer the criterion of engineering design and construction. The building of proper analysis method of mechanical model according with practice is critical of mathematics mechanics analysis . Mechanical model common in use: rigid dynamics model, elasti

24、city and elasto-plasticity model, rheological model, fracture mechanical model, failure mechanical model, penetration mesh model and topology model., integral multidisciplinary analysis method The researches of rock mechanics and engineering adopt many methods and think kinds of factors to multidisc

25、iplinary analysis and evaluation especially the combination of theory and experience to get correct results. Integral multidisciplinary analysis method should be directed by uncertainty analysis in rock engineering. The uncertainty factors behave in engineering 、geology and construction. In this way

26、 research can get rid of the influence of traditional certainty method of solid mechanics to get results more practical.,1.4 intrinsic complexity of rock mechanics Rock mechanics manifests a lot of theory, knowledge and analysis methods reference with applied mechanics field. The reasons why rock me

27、chanics is an engineering subject alonely have six parts as follows: (1) failure feature of rock Theory based on engineering mechanics commonly could not be applied directly into the case of rock failure.,(2) scale effect Joint existing in body and crack produced because of geology form macroscopic

28、plane of discontinuity. Strength and deformation feature of body are influenced by characters of rock material and all kinds of structure plane. Characters of rock break by drilling head express during drilling are usually the strength characters of integral rock.,Excavating tunnel in joint rock cou

29、ld reflect the feature of joint system. The fractured surface is determined by the orientation of joint. The damage of Marlborough arch dam was caused by movement of mass of rock formed by fracture and joint in 1959. Larger scale rock stack express quasi-continuous medium characters. The methods to

30、solve problems are different because of the difference of relative scale between engineering object and body.,(3) tensile strength Rock is different from other engineering materials because of the low tensile strength (besides concrete). Stress expressed in uniaxial tensile strength test is lower on

31、e quantity degree than uniaxial compression test. It is because joint and other cracks in rock can resist very little tensile stress. So rock is called no tensile material in case of zero of tensile strength of body. The character of no tensile in rock means mud loss occurred in case tensile stress

32、occurred during casing program designs in drilling engineering.,(4) influence of underwater Underwater affects the character of body in two way. The obvious way functions through effective stress. Pressure water reduces the valid normal stress so as to reduce the shear stress because of friction whi

33、ch leads to finally strength. Another effect is underwater has ill effects in special rock and mineral. For example clay band can soften in underwater which will both reduce strength of body and increase the deformation of body.,The effect of underwater on character of body is emphasized in gas and

34、oil engineering. Water base drilling fluid immerges into argillaceous rock (mud rock) during drilling which will reduce the strength and well destabilization; water injection is one of the main measurement to enhance oil recovery. But injection of water will alter the strength of argillaceous rock a

35、nd reduce porosity, permeability, and make sanding, production falling.,(5) weathering Definition of weathering is that chemical or physical change in rock because of its surface dissolved by air and water. Weathering has an ill effect on engineering because it plays an important effect on integrity

36、 material feature and frictional coefficient of rock surface. Weathering makes rock character soften and reduces frictional coefficient gradually.,For petroleum engineering, there is one problem should be pay attention: the core have stocked in the core library for several years, and some of them ha

37、ve heavily weathered, so the experiment result can not present the reality of the formation rock. (6) Outside stress To general engineering structure, the outside stress is clear when do the stress analysis. But to rock underground, it is very difficult to get the origin stress loading on the rock.

38、It is an important research interest to determine the origin stress loading on the rock under ground.,1.5 Prime application of rock mechanics From using stone tool at remote antiquity to cutting mineral and laneway, building hydro project, constructing bridge and tunnel and oil drilling, people have

39、 always being contact with rock. So, rock mechanics is widely used and related to all kinds of the national economy and the peoples livelihood.it is base of many important project.Sum up, there are some important applications as follow:,(1) Mining engineering Including surface mining and underground

40、 mining. Surface mining need rock mechanics to analyze stabilization of slope of handwork and savageness rock; Underground mining also base on rock mechanics to analyze stabilization of mine tunnel and crash of underground rock.,(2) Development and utilization of energy resources Including building

41、underground power station, constructing storage of oil and gas, disposing underground nuclear waste and developing hydraulic water resource, geothermal resources and oil resource can not be part from development of rock mechanics. In reverse, development and utilization of energy resources also help

42、 the development of rock mechanics. Especially from 20 century 50 years, lager scale hydraulic project in the world, for instances constructing Brazilian Etape hydraulic power plant,Chinese GeZhouBa hydraulic project and SanXia hydraulic project greatly drive and accelerate the development of rock m

43、echanics.,(3) In traffic domain, more and more constructing of bridge and tunnel is related to stabilization,deformation and strengthening of wall rock such as submarine tunnel of English Channel. (4) As more and more high-rise buildings, rock mechanics become more and more important and widely used

44、 for analyzing stabilization and deformation of base. (5) In military domain, all kinds of combat readiness tunnel, underground blindage, airport and port and so on are cant without the development of rock mechanics.,(6) Geologic structure Rock mechanics is also widely used to research geological st

45、ructure, such as probing into movement of lithosphere, crust deformation and the interrelationship of tectonic（构造） stress field, studying deformation and failure rule of rock at high temperature and high pressure, and researching character of rock creep and rule of form, spearing and evolvement of f

46、racture.,(7) Earthquake prediction and geologic hazard analysis Rock mechanics emphasizes on studying engineering, such as stress field redistribution, including dynamics feature of rock and prediction of failure of rock, brought by constructing large scale hydro project, building tall building and

47、underground mining.,(8) Application of rock mechanics in petroleum industry Rock mechanics is widely used in all domain of petroleum industry from exploration to development. Form, spreading, evolvement （演变）and distribution of natural fracture in exploration, failure of rock, well path control, stab

48、ilization of borehole and casing programme optimization design in drilling process, well completion pipe string optimization design,well completion system optimization design and , well completion optimization design in well completion,prediction of casing completeness and mechanism analysis of casi

49、ng collapse in cementing, form spreading of hydraulically created fracture and its optimization design in stimulation treatment, dynamic rule of variation of fracture and pore of reservoir and its influence on flowing of fluid and development of low permeability and porosity and extremely low permea

50、bility and porosity reservoir are all interrelated to rock mechanics.,1.6 Rock mechanics study features in petroleum engineering Features Deep depth Invisible Coupling of deformation and fluid Many types of rock melted Research Fields Mechanism of rock breaking and drill capability Drilling Build up

51、 prevention Borehole instability Hydraulic fracturing Sand production Casing damage Reservoir deformation Surface sinking,End of This Chapter!,Chapter 2 The Fundamental of Elastic Mechanics,force,Outside force,Internal force,stress,normal stress,shear stress,The sign of the stress,spot stress state,

52、Stress tensor,Stress invariants and deviatoric stress,Mohrsstress circle,Strain and strain tensor,Elastic moduli and Poissons ratio,poroelasticity,force,Outside force,Internal force,Outside force: surface force( point force and distribution force), body force.,P,point force,distribution force,body f

53、orce,Act on every mass point of the mass body, so called Quality force. As Gravity, Electromagnetic force,Internal force,reaction force of outside force,Equal but Opposite direction,stress,normal stress,shear stress,The sign of the stress,stress,Cross section,Relation between active force and active

54、 surface is any orientation. If active force points towards normal surface, it is normal force, otherwise it is shear force, pointing towards tangential surface.,Compressive stress +,Tension stress _,The sign of the stress,positive,negative,X,Y,counterclockwise,clockwise,Divided normal stress and sh

55、ear stress A stress state is： =x,y,z,xy,yz,zx,R,=R/A,z,y,x,xyzx,spot stress state,Unit body,matrix,y yz yx,z zx zy,x xz xy,spot stress state,x,y,z,Stress tensor,Stress tensor,Stress tensor,Stress invariants and deviatoric stress,In rock mechanics,we regulate: 1 2 3 As 1 stand for the maximum princip

56、al stress, 3 stand for the minimum principal stress, 2 intermediate principal stress. Mohrsstress circle Mohrs stress circle is a tool to analyze the two-dimension spot stress state. We will mainly introduce the mohrs stress circle under two-dimension stress state,thats to say the plane stress state

57、.,Mohrsstress circle,Mohrsstress circle,angle,Strain and strain tensor,Strain and strain tensor,Elastic moduli and Poissons ratio,three-dimension,poroelasticity,How to describe the rock? ground and Underground,What about the fluid in the pore is ?,How to interact between the water and the Rock matri

58、x?,Volume decrease,Particle Volume decrease,Water Volume increase,Effective stress,Pore pressure,Biot Coefficient,Rock is a kind of solid body with its mechanics residing solid body mechanics. Solid body is a kind of continuous medium in macroscopic state. But mass of rock contain lots of cleavage裂缝

59、, faultage（断层） instead of microcrack微裂纹 discontinuity surface.That to say mass of body is discontinuous. It usually displays anisotropy. If it contains water it will present two-phase. Rock Mechanics is a frontier science between solid body mechanics and geologic engineering.,Anisotropy,rock material and rock mechnics,Rock material character: heterogeneous （异构）porous medium；anisotropy；condition correlation；scale relation；rate of loading.,Ex. 1 Determing the internal force in each area and their s