rock mech chap2第2章 基础力学

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,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,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 force,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 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,Shear,stress,-,Shear,stress,+,X,Y,counterclockwise,clockwise,Divided normal stress and shear stress,A stress state is,：,=,x,y,z,xy,yz,zx,R,=,R,/A,z,y,x,xy,zx,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 principal 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,.,Mohrsstress,circle,2,1,1,2,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 matrix?,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,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,material,material,character,mechanics,research,mechanics character,steel,single-phase,isotropy,deformation,damage,Plasto,-elasticity mechanics,fracture mechanics,damage mechanics,rock,heterogeneous,（异构）,porous medium,anisotropy,deformation,damage,rock mechanics,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 stresses in the following,sylinder,.,A1,A2,A3,F,F,F=200Kg,A1=20cm,2,A2=10cm,2,A3=40cm,2,Ex.2,If 1=120MPa,2=40MPa,and the surface,pls,determine the normal stress n and shear stress?,Normal direction of the surface is 30,