An anisotropy in the elastic moduli values of intact rock with a ratio of more than 1.3–1.5 has been reported to have an effect on the calculated magnitudes and orientations of the in situ principal stress components as measured by the overcoring method.

Keywords: in situ, stress, measurement, rock, overcoring, sidecoring, LVDT cell 1 Introduction Understanding the in situ stress field around an excavation is a very important input into the design process and necessary for continued successful excavation development. In complex mining environments, the

becomes higher while increasing the initial in-situ stress ratio, even for very deep tunnels. Furthermore, an empirical equation to obtain the displacements of the ground surface, tunnel wall and tunnel crown has been obtained after a multiple linear regression analysis.

• Authors: Diego Lope AlvarezAbout: Geotechnical engineering[PDF]

racy of linear poroelastic model for estimation of horizontal stresses. 1. Introduction It is important to have a full knowledge of in-situ stresses before carrying out any rock stress analysis. The main reasons for the determination of horizontal in-situ stres-ses are: .

To obtain the rock mass elastic modulus at the measuring points for in situ stress, we should calculate the rock mass elastic modulus at the required depth based on the measured data. As the depth of the adjacent measuring points changes by no more than 3 m, a two-dimensional linear interpolation method can be used to obtain E cm where

In situ rock stress measurements from existing tunnels with LVDT-cell. LVDT-cell version II Eight radial LVDT sensors Rock and cell temperature sensors ... -assumes linear elastic isotropy or known transverse ... Experience with a new LVDT-Cell to measure in-situ stress from an existing tunnel 0 20 40 60 80 100 R1 R2 R3 R4 R6) Sample Surface A ...

A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will sometimes form a deep fissure or crevice in the rock. Fractures are commonly caused by stress exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. Fractures can provide permeability for fluid movement, such as water ...

Keywords: in situ, stress, measurement, rock, overcoring, sidecoring, LVDT cell 1 Introduction Understanding the in situ stress field around an excavation is a very important input into the design process and necessary for continued successful excavation development. In complex mining environments, the

been studied in situ, although laboratory results for metamorphic rocks have shown evidence for anisotropy at least since the early 1960s (Christensen, 1965, 1966; Gebrande, 1982). There are several reasons why the anisotropy of the crystalline crust has not traditionally been investigated.

Estimation of in-situ horizontal stresses using the linear poroelastic model and minifrac test results in tectonically active area ... It is important to have a full knowledge of in-situ stresses before carrying out any rock stress analysis. The main rea-

racy of linear poroelastic model for estimation of horizontal stresses. 1. Introduction It is important to have a full knowledge of in-situ stresses before carrying out any rock stress analysis. The main reasons for the determination of horizontal in-situ stres-ses are: .

The implicit treatment gives rise to a large nonlinear algebraic system of equations that must be solved at each timestep. Newton-like iterative methods are often used to solve these nonlinear systems. At each nonlinear iteration, large and sparse linear systems must be solved to obtain the Newton update vector.

The largest in situ horizontal principal stress is calculated based on Eq. (10) which assumes linear elasticity and that the effect of fracturing on fluid rock infiltration is insignificant. More elaborate pore pressure corrections have been proposed (e.g. [4]) which .

Chapter 5 in Comprehensive Rock Engineering: Principles, Practice and Projects, Vol. II, Analysis and ... tion to earthquake mechanics,8—10 in situ stress determination,7,11 sea bottom instability under ... the linear constitutive relations can be obtained by extending the known elastic expressions. In

RocData is a versatile toolkit for the analysis of rock and soil strength data, and the determination of strength envelopes and other physical parameters.RocData includes RocProp, a database of intact rock properties that runs as a standalone application.. RocData can be used to determine the parameters of linear and non-linear strength envelopes for rock and soil, based on the analysis of ...

The magnitude and orientation of in situ rock stresses cannot, generally, be predicted theoretically and must therefore be determined experimentally. Expressions for stresses developed around the walls of a circular hole in an elastic medium due to arbitrarily oriented 3-dimensional stresses are ...

tio of the present rock, but to the mean in situ effective stress. Furthermore, Juhasz (1986) applied it as a correction factor to the pore volume (Eq(1)), whereas it would be equally appropriate in the case of linear elasticity, and more aprropriate for nonlinear elasticity to apply the correction factor directly to the a pplied hydrostatic ...

Geomechanical Modeling of In-Situ Stresses Around a Borehole Samantha Grandi, Rama Rao, and M. Nafi Toksoz ... require some knowledge of the mechanical behaviour of the rock. The lack of ... ment gradients are sufficiently small for the theory of linear elasticity to be valid. The equations of motion,

In 1987 a rock panel with engravings and cup marks from the Early Bronze Age was found on the outskirts of the town of Kongsberg in Norway. Among the engravings was discovered a Cretan-Minoan inscription, consisting of five Linear A letters or syllables. Nothing like this has ever been found outside the Aegean region. But,.

estimate rock mass modulus from empirical relations, often non-linear, developed by comparing -situ test in measurements with rock mass classification schemes, e.g. RMR, GSI, and Q (Hoek and Diederichs, 2006).For massive rock (i.e. rock masses containing few joints), Palmström and Singh (2001) proposed the simplified