Geotechnical Study of the Rocks in Qatar and Construction Techniques
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The American University in Cairo The School of Sciences and Engineering Engineering Characteristics of Rocks in Qatar; Applications on Excavation and Tunneling A thesis submitted to The Department of Construction Engineering In partial fulfillment of the requirements for the degree of Master of Science in Construction Engineering By Ahmed Fawzy Kassem Under the Supervision of Prof. Safwan Khedr Professor of Construction Engineering, AUC Dr. Nasser A. Alnuaimi Department of Civil and Architectural Engineering, Qatar University Spring 2016 Abstract Excavation as well as tunneling have become fundamental operations in the advanced civil engineering field. In Qatar, many subsurface construction operations take place in rocks. However, the lack of studies and research that analyze the subsurface rock components from a geotechnical engineering perspective has created unexpected construction conditions. Most of similar studies handled concerns about properties related to oil and gas fields. This research aims to provide a geotechnical study for rocks in Qatar, and to illustrate the impact of the existence of these rock layers on two civil applications; namely excavation and tunneling. During this study, soil investigation reports and rock samples are collected from several bores located in Qatar, and a classification system is utilized to classify the rock samples to identify and study the properties of the existed rocks. Also, numerous production rates from different tunneling and excavation projects are recorded and analyzed, in order to clarify the relation between these rates and the classified rock layers. Based on this analysis, a geotechnical study and mapping system for the rocks in Qatar are presented. Reliable tools for predicting the average productivities of excavation and tunneling projects in Qatar are developed, these tools are aiming to facilitate designing, bidding and executing processes involved with these types of rocks. Table of Contents List of Figures ................................................................................................................................. 4 List of Tables .................................................................................................................................. 6 List of Equations ............................................................................................................................. 7 Chapter One: Introduction ........................................................................................................... 8 1.1 Problem Statement ........................................................................................................... 8 1.2 Qatar Geology ................................................................................................................ 10 1.2.1 General .................................................................................................................... 10 1.2.2 Surface Geology...................................................................................................... 14 1.3 Objectives of the Research ............................................................................................. 17 1.4 Research Approach and Scope of Work ........................................................................ 17 1.4.1 Research Approach ................................................................................................. 17 1.4.2 Scope of Work ........................................................................................................ 18 Chapter Two: Literature Review ............................................................................................ 19 2.1 Current Construction Challenges ................................................................................... 19 2.2 Geology of Qatar ............................................................................................................ 19 2.2.1 Description .............................................................................................................. 19 2.2.2 Shaliness Factor ...................................................................................................... 26 2.3 Characterization of rocks in Qatar ................................................................................ 29 2.4 Challenges face engineers dealing with Rocks in Qatar ................................................ 36 2.5 Rock Sampling ............................................................................................................... 39 2.6 Uniaxial compressive strength Test ASTM D 7012 ...................................................... 39 2.7 Point load test ASTM D5731 ......................................................................................... 42 2.7.1 The Point load strength index (Is50) ........................................................................ 43 2.8 Testing Experience for Rocks in Qatar .......................................................................... 44 2.8.1 UCS and Point load test relation ............................................................................. 44 2.8.2 Rock Testing in Qatar ............................................................................................. 45 2.9 Rock Classification Systems .......................................................................................... 47 2.9.1 General .................................................................................................................... 47 2.9.2 Terzaghi's Rock Mass Classification ...................................................................... 48 2.9.3 Classifications involving stand-up time .................................................................. 49 2.9.4 Rock Structure Rating (RSR).................................................................................. 51 2.9.5 Rock Mass Rating RMR ......................................................................................... 53 2.9.5.1 Modifications to RMR for Mining ....................................................................... 56 2.9.6 Rock Tunneling Quality Index, Q ........................................................................... 57 2.9.7 Geological Strength Index GSI ............................................................................... 58 2.9.8 RESULTS ............................................................................................................... 58 2.10 RQD%: A Classification System and Rock Parameter ............................................. 61 2.11 Tunneling Technique ...................................................................................................... 63 2.11.1 General .................................................................................................................... 63 2.11.2 Microtunneling ........................................................................................................ 63 2.11.3 Tunneling Operation ............................................................................................... 64 2.11.4 Favorable Soil Conditions....................................................................................... 73 2.11.5 Tunneling Machine Cutter Head Discs ................................................................... 74 2.12. Excavation Technique ............................................................................................... 83 2.12.1 General .................................................................................................................... 83 Chapter Three: Research Approach .......................................................................................... 86 3.1 Geological Study ........................................................................................................... 87 3.2 Sampling and Soil Investigations ................................................................................... 88 3.3 RMR Classification System and Implementation .......................................................... 90 3.4 Construction Projects - Excavation and Tunneling - Data Collection ........................... 93 3.5 Data Analysis ................................................................................................................ 95 Chapter Four: Data Analysis ................................................................................................... 97 4.1 General Qatar Rock Map ................................................................................................ 97 4.2 RMR Classification System ........................................................................................... 99 4.2.1 How it works ........................................................................................................... 99 4.2.2 RMR Calculations ................................................................................................. 100 4.2.3 RMR Evaluation ................................................................................................... 102 4.3 Qatar Rock Map according to RMR grades ................................................................ 103 4.4 RMR Results Analysis ................................................................................................. 105 2 4.4.1 Overview of the Rock Layers Existed at the Studied Locations .......................... 105 4.4.2 Rock Layers Parameters Comparison ......................................................................... 106 4.4.3