Analysis of stiffness for anisotropic rock masses by borehole jack test

• Published in: Japanese Geotechnical Journal Vol. 17; no. 3; pp. 393 - 400
• Main Authors: MATSUI, Hiroya, TANI, Kazuo, KATO, Takeshi, OHNO, Hirokazu, TOGASHI, Yota, KAWAKUBO, Shohei
• Format: Journal Article
• Language: Japanese
• Published: Tokyo The Japanese Geotechnical Society 01.09.2022; Japan Science and Technology Agency
• Subjects: Analysis; anisotropic rock masses; Anisotropic rocks; Anisotropy; back analysis; borehole jack test; Boreholes; Elasticity; exact elastic solution; Exact solutions; Field tests; Load tests; Mechanical properties; Methods; Modulus of elasticity; Pressuremeter tests; Rock masses; Stiffness; Theoretical analysis; transversely isotropic
• ISSN: 1880-6341; 1880-6341
• DOI: 10.3208/jgs.17.393

Plate load test and pressuremeter test are common in-situ tests to evaluate the stiffness of rock masses. However, a method to evaluate the anisotropic nature of stiffness of rock masses has not been established yet. In this paper, a method is proposed to evaluate the Young’s modulus of anisotropic rock masses by borehole jack test. The theoretical analysis is based on an orthotropic elasticity and the displacements along the borehole wall are derived from the exact solution. In the latter half, back analysis method is shown and the relevant two Young’s moduli for the orthotropic rock masses are obtained using in-situ data to validate the proposed method.