tailieunhanh - DEVELOPMENTS IN HYDRAULIC CONDUCTIVITY RESEARCH Phần 2

Tham khảo tài liệu 'developments in hydraulic conductivity research phần 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 18 Developments in Hydraulic Conductivity Research Determination of the parameters for the proposed model Some of the experimental values of the mechanical parameters of the fracture specimen during the coupled shear-flow tests are listed in Table 2 taken from Table 1 in Esaki et al. 1999 . Using the data as listed in Table 2 we plot the peak shear stress versus normal stress curve in Fig. 8 which can be fitted by a linear equation rp n with a high correlation coefficient of . Therefore the shear strength of the specimen can be derived as ự and c MPa respectively. ơn MPa Tp MPa ks0 MPa mm 1 5 10 20 Table 2. Mechanical parameters of the artificial fracture After Esaki et al. 1999 The initial normal stiffness of the fracture of the specimen kn0 has to be estimated from the recorded initial normal displacement with zero shear displacement under different normal stresses. From the data plotted in Fig. 9 which is taken from Fig. 7b in Esaki et al. 1999 kn0 can be estimated as kn0 100 MPa mm by considering the possible deformation of the intact rock under high normal stresses. It is to be noted that in the remainder of this section the hard intact rock deformation of the small specimen is neglected meaning that the normal displacement of the specimen mainly occurs in the fracture of the specimen and it is approximately equal to the increment of the mechanical aperture of the fracture. Theoretically the decay coefficient of the fracture dilatancy angle r can be directly measured from the normal displacement versus shear displacement curves as plotted in Fig. 9. A better alternative however is to fit the experimental curves using Eq. 31 such that the least square error is minimized. By this approach we obtain that r with a correlation coefficient of . Fig. 8. Peak shear stress versus normal stress curve of the fracture. Stress Strain-Dependent Properties of Hydraulic Conductivity for