Deformation modulus of heavily jointed-sheared and blocky greywackes by pressuremeter tests: Numerical, experimental and empirical assessments

IŞIK, Nihat Sinan
Doyuran, Vedat
Deformability of rock masses influencing their behavior is an important geomechanical property for the design of rock structures. Due to the difficulties in determining the deformability of jointed rock masses at the laboratory-scale, various in-situ test methods such as pressuremeter, dilatometer, plate loading tests etc. have been developed. Although these techniques are currently the best and direct methods, they are time-consuming and expensive, and present operational difficulties. In addition, the influence of the test volume on deformation modulus depending on the method employed is also important. For these reasons empirical equations to indirectly estimate the deformation modulus have also been recommended by several investigators as an alternative approach. In this study; the geomechanical quality of weak, heavily jointed, sheared and/or blocky greywacke rock masses, on which very concentrated civil works are continuing at the southern and southwestern parts of Ankara (Turkey), was assessed. The deformation modulus was determined by pressuremeter tests, the possible effects of variables on the derived deformation modulus from the pressuremeter test were evaluated by numerical methods, and the comparisons between the deformation modulus of the greywackes obtained from the pressuremeter tests and their geomechanical quality (GSI and RMR) were made. Numerical simulations revealed that the presence of a disturbed annulus around the borehole causes underestimation of the deformation modulus, while the effect of length to diameter ratio of the pressuremeter probe on the deformation modulus is minor. Based on the geoengineering characterization assessments, mainly two greywacke rock masses with different geomechanical qualities were identified. Geotechnical quality of one of these rock masses was verified by the back analysis of two slope failures. The empirical equations to indirectly estimate the deformation modulus of the greywackes using their GSI and RMR values yielded high coefficients of correlation.


Probabilistic-numerical modeling of stability of a rock slope in Amasya-Turkey
Gheibie, Sohrab; Akgün, Aykut; Department of Mining Engineering (2011)
Rock slope stability is considered as one of the most important fields in rock engineering. Developments of computation facilities and increase in application of sophisticated mathematical concepts in engineering problems have also affected the methods of slope stability analysis. In recent years, the numerical modeling methods have extensively applied instead of limit equilibrium methods. Also, the probabilistic methods are considered in rock slope designs to quantify the uncertainties of input effecting v...
Shear mode rock fracture toughness determination with a circular plate type specimen under three-point bending
Şener Karakaş, Sinem; Tutluoğlu, Levent; Department of Mining Engineering (2011)
Fracture toughness is an important rock property for rock fracturing and fragmentation applications. Theory and practice of opening mode (mode I) and shearing mode (mode II) fracture toughness tests are still in a developing stage for the cylindrical rock cores. A new circular plate type test specimen is used for mode II fracture toughness testing on rock cores. This involves a straight edge notched circular plate type core disc geometry under three-point bending load; new method and its associated specimen...
Numerical modeling of discontinuous rock slopes utilizing the 3DDGM (three-dimensional discontinuity geometrical modeling) method
Azarafza, Mohammad; Asghari-Kaljahi, Ebrahim; Akgün, Haluk (Springer Science and Business Media LLC, 2016-5-5)
The geometry of discontinuities in a rock mass is one of the most important influences on the behavior and characteristics of that rock mass. The geometry of discontinuities largely determines the stability of the rock mass, as well as appropriate methods for reinforcing and stabilizing that mass. This study introduces the 3DDGM (three-dimensional discontinuity geometrical modeling) method, which is based on the 3DGM (three-dimensional geometrical modeling) algorithm that was developed using the Mathematica...
Erkayaoğlu, Mustafa; Kırmacı, Alper (2019-09-01)
Rock bolts are widely used in tunnels, underground openings, and also rock slopes to provide support and attach blocks to therock mass in various engineering fields. They have a significant role for the stability of underground structures and natural rock slopes bothin the mining and civil engineering industry. The understanding of the rock bolt behavior under stress conditions plays a key role in the longterm stability and sustainability of rock slopes, nearby structures, and underground openings. The dete...
Development of a 2D and 3D computational algorithm for discontinuity structural geometry identification by artificial intelligence based on image processing techniques
Azarafza, Mohammad; Ghazifard, Akbar; Akgün, Haluk; Asghari-Kaljahi, Ebrahim (2019-07-01)
Block geometry is commonly the most important feature determining the behaviour of a rock mass and directly controls the structural instability in underground openings or surface cuttings. Various methods are used to estimate block geometry and to perform a block survey, and these are standardly divided into empirical-based methods (e.g. spot mapping, linear mapping, areal mapping) and computer-based methods (e.g. laser scanning, image processing, digital image mapping). Empirical approaches are associated ...
Citation Formats
N. S. IŞIK, R. ULUSAY, and V. Doyuran, “Deformation modulus of heavily jointed-sheared and blocky greywackes by pressuremeter tests: Numerical, experimental and empirical assessments,” ENGINEERING GEOLOGY, pp. 269–282, 2008, Accessed: 00, 2020. [Online]. Available: