第三章_岩石的力学性质-4-练习.ppt

* Chapter 3 Mechanical Properties of Rock Tang Lizhong . Institute of Rock Soil Mechanics and Engineering, Central South University (1) From the data given in Figure 1, calculate the tangent modulus and Poisson’s ratio for the initial elastic behaviour of the limestone with σ3 = 2.0 MPa. Figure 1. Results of triaxial compression tests on an oolitic limestone with volumetric strain measurement 3.6 问题/Problems * Chapter 3 Mechanical Properties of Rock Tang Lizhong . Institute of Rock Soil Mechanics and Engineering, Central South University (2) A porous sandstone has a uniaxial compressive strength of σc = 75 MPa. The results of a series of triaxial compression tests plotted on shear stress–normal stress axes give a linear Coulomb peak strength envelope having a slope of 45?. Determine the axial stress at peak strength of a jacketed specimen subjected to a confining pressure of σ3 = 10 MPa. If the jacket had been punctured during the test, and the pore pressure had built up to a value equal to the confining pressure, what would the peak axial stress have been? 3.6 问题/Problems * Chapter 3 Mechanical Properties of Rock Tang Lizhong . Institute of Rock Soil Mechanics and Engineering, Central South University (3) (a) Establish an approximate peak strength envelope for the marble for which the data shown in figure 2 were obtained. (b) In what ways might the observed stress–strain behaviour of the specimens have differed had the tests been carried out in a conventional testing machine having a longitudinal stiffness of 2.0 GNm?1? Assume that all specimens were 50 mm in diameter and 100 mm long. Figure 2. Complete axial stress– axial strain curves obtained in triaxial compression tests on Tennessee Marble at the confining pressures indicated by the numbers on the curves. 3.6 问题/Problems * Chapter 3 Mechanical Properties of Rock Tang Lizhong . Institute of Rock Soil Mechanics and Engineering, Central South