Abstract
When only limited borehole data are available, making optimum use of the existing data is crucial for performing a preliminary assessment of the investigated site. In this paper, the relationships between the borehole data and the permeability coefficient were first analyzed. These relationships were then used to establish a model for estimating the permeability coefficient of rock mass that takes into account the influence from the confining pressure on the seepage flow. The proposed model can reduce the number of hydraulic tests which are time consuming and very costly and allow the determination of change in the permeability coefficient throughout the borehole. The flow model could assist in providing important references for selecting an appropriate permeability coefficient in hydrogeological simulation and in evaluating the condition of large cracks developed in boreholes. In general, the seepage flow model developed in this study will contribute to the design practice of a tunnel project constructed in fractured rock masses.
Highlights
E research methods mentioned above are generally too sophisticated for engineers to use in practice
We established the relationship between the parameters of the structural plane in the fractured rock mass and the permeability coefficient of the fractured rock mass by analyzing several crack indices such as aperture and inclination angle
0.10401 0.09490 0.10484 0.02719 0.00302 0.00739 0.00336 0.00671 0.00537 0.00302 0.01074 0.00705 0.00906 0.02820 0.00403 where Km is the permeability coefficient of the section (m/s), n is the number of cracks, ami is the mechanic aperture (m), JRCi is the roughness coefficient, c is the volumetric weight (N/m3), μ is the viscosity (Pa·s), and θi is the inclination angle of the crack (°)
Summary
2.1. eoretical Basis of Permeability Coefficient of Fractured Rock Mass. Poiseuille derived a theoretical formula to describe the motion of a viscous incompressible fluid in the gap between smooth parallel plates under homogeneous and constant velocity conditions; it is expressed as [18]. Where u is the flow rate (m/s), g is the gravitational acceleration (m/s2), b is the width between smooth parallel plates (m), ] is the kinematic viscosity coefficient of water (m2/s), and J is the hydraulic gradient. E width between two parallel plates can be treated as the crack width of the ideal fractured rock layer. If the crack system is treated as a lot of straight cracks and all the apertures are considered equal, the flow velocity along the line of intersection of the fracture group is given by NB2 c v · J,. In the smooth parallel-plate model, the fracture system is treated as multiple equal-width and flat-fracture groups. Erefore, several additional factors neglected by the smooth parallel plate model need to be considered when analyzing the permeability coefficient in engineering practices. Erefore, several additional factors neglected by the smooth parallel plate model need to be considered when analyzing the permeability coefficient in engineering practices. ese
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
