Rock Mass Strength Analysis and Disturbance Factor Estimation of Heterogeneous Rock Masses for the Dam Foundation: A Case Study at Kanarwe River Basin, Kurdistan Region, NE-Iraq

DOI

10.2991/978-94-6463-258-3_25How to use a DOI?

Keywords

Disturbance factor; GSI; Volumetric joint counting; RocLab software

Abstract

Evaluating rock masses for dam foundations, especially heterogeneous rock (flysch), becomes imperative and requires accurate geomechanical classifications. The rocks at the Kanarwe River Basin (KRB), especially at a proposed dam site (Goma-Qazan near Khewata – Sura Qalat villages), mainly consist of interlaying massive carbonate rocks of the Aqra Formation with flysch rocks of Tanjero Formations. Therefore, selecting appropriate dam types is challenging and very risky. This study conducted a detailed survey of lithology, discontinuity condition, rock sampling and laboratory tests to determine the site suitable for dam construction using the quantitative GSI, Rock Mass Rating (RMR), and Dam Mass Rating (DMR) geomechanical classification systems for twenty units. A new procedure was suggested for quantifying stress relaxation and damage level (disturbance factor D) in rock masses. Calculating rock mass units’ disturbance factor based on the joint spacing, strength index (Is50), and excavabilty methods are very proper to add as a new feature for RocLab software for evaluating foundation rock masses. The rock mass strength is calculated based on the RocLab software program. The maximum deformation modulus of rock mass (Em) is 33797 MPa for carbonate rock mass unit and 1348 MPa for flysch rock. The excavation in hard massive carbonate rocks required blasting led to disturbance and stress relaxing in the rock mass by 0.4. In contrast, excavation in flysch rocks required easy ripping, which led to disturbance and stress relaxing in the rock mass by 0.2. The geological strength index value results for rock masses units at the dam site reveal that the carbonate rocks are nearly between 74–76, but flysch rock is between 35–55.

Copyright

© 2023 The Author(s)

Open Access

Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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TY  - CONF
AU  - Fahmy Osman Mohammed
AU  - Ghafor Ameen Hamasur
AU  - Diyari Ali Almanmi
PY  - 2023
DA  - 2023/11/08
TI  - Rock Mass Strength Analysis and Disturbance Factor Estimation of Heterogeneous Rock Masses for the Dam Foundation: A Case Study at Kanarwe River Basin, Kurdistan Region, NE-Iraq
BT  - Proceedings of the Rocscience International Conference  (RIC 2023)
PB  - Atlantis Press
SP  - 233
EP  - 244
SN  - 2589-4943
UR  - https://doi.org/10.2991/978-94-6463-258-3_25
DO  - 10.2991/978-94-6463-258-3_25
ID  - Mohammed2023
ER  -