Engineering Geology for Underground Rocks

verfasst von: Professor Supping Peng, Dr. Jincai Zhang

Verlag: Springer Berlin Heidelberg

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

Engineering geology for underground rocks is a sub-discipline of engineering geology for describing and solving geological engineering problems encountered in underground mining, petroleum and civil engineering. It covers rock mechanics for underground rocks, rock hydraulics, wellbore mechanics, mine geology and mine hydrogeology.

This book clearly and systematically explains underground engineering geology principles, methods, theories and case studies, depicts engineering problems in underground rock engineering and how to study and solve them. It specially emphasizes mechanical and hydraulic couplings in rock engineering for wellbore stability, mining near aquifers and other underground structures where inflow is a problem. Using the methods and models given in this book, the reader is able to analyse underground geological engineering problems and also for the design of underground structures.

Professionals and students in engineering geology, geological, mining, petroleum, civil engineering, rock mechanics, and mine geology will find this an essential reference.

Inhaltsverzeichnis

Frontmatter

1. Rock properties and mechanical behaviors

Abstract

Rock physical and mechanical properties are very important parameters for geological engineering design and construction. For instance, in coal mining industry many geological disasters induced by mining were associated with misunderstanding of rock mechanical properties (Peng 1998a, Han and Peng 2002). Rock physical properties include density, porosity, and permeability, etc. Rock mechanical properties mainly include elastic modulus, Poisson’s ratio, and rock strength. These parameters can be obtained by lab experiments of core samples or by in-situ tests. The other characteristics of rocks include time-dependent rheological and creep behaviors (Wang 1981). When the rock samples are not available, such as oil and gas drilling and mining at deep depth, the well log data and geophysical data can be used to analyze and interpret rock physical and mechanical parameters (Peng 1997, Peng 1999).

2. Sedimentary environments and geologic structures

Abstract

Sedimentary environments are important for investigating rock physical, geological, and geomechanical behaviors (Peng and Zhang 1995). The brief overview of sedimentary geology is introduced in this section.

3. In-situ stress and pore pressure

Abstract

In-situ stress magnitudes and orientations play a very important role in geological engineering, and they are the most basic parameter inputs in design of underground structures. One of the main functions of rock mechanics has been to determine in-situ stress. In-situ stress is characterized by the magnitudes and directions of three principal stresses. Generally, in-situ principal stresses are consisted of three mutually orthogonal stresses, i.e. vertical stress (σ_V), minimum horizontal stress (σ_h), and maximum horizontal stress (σ_H). In different geographic, geologic, and tectonic regions, in-situ stress magnitudes and orientation are very different. The three in-situ stress magnitudes and orientation are very different. The three in-situ stresses correspond to three principal stresses, namely greatest stress (σ₁), intermediate stress (σ₂), and least stress (σ₃). According to the relationships between princiaal stresses and vertical, minimum and maximum horizontal stresses, three in-situ stress regimes (Fig. 3.1) can be used to describe tge stress states, i.e.:

4. Rock strength experiments and failure criteria

Abstract

There are many types of laboratory tests to obtain rock mechanical properties. Laboratory tests usually consist of simple experiments appropriate to the nature of the rock in which important quantities, often stress and strain, are determined (Jaeger and Cook 1979). Before laboratory tests, rock sample preparation and physical analysis are needed. The ISRM standards gave the suggested methods for both core preparation and testing (Brown 1981, Kovari et al. 1983).

5. Sedimentary rock masses and discontinuities

Abstract

One of the most prominent features of the earth’s upper crust is the presence of joints and fractures at all scales. The fractures and joints usually are named to be discontinuities. A rock mass consists of both rock blocks and discontinuities. A rock block/matrix and a rock mass have significant differences in geomechanical behaviors. Nearly every physical property of sedimentary rock (such as mechanical properties; hydraulic, thermal, and electrical conductivities; and acoustic properties) is determined to some extent on the fractures and the fluids they contain. The success of many applications such as efficient recovery from fractured reservoirs, hazardous waste disposal, and geothermal energy extraction depends on a thorough understanding of fracture behavior. Many petroleum reservoirs and coal seams are situated in fractured porous formations. Thus, prior to any rock engineering it is necessary to determine the geometrical and mechanical properties of the fractures and rock mass from lab and the field. For instance, the geometry, locations, orientation, aperture variations and fluid-mechanical properties of fractures and rock mass are needed to be determined.

6. Double porosity poroelasticity and its finite element solution

Abstract

Field observations have revealed a need for a better and more comprehensive method for geomechanics modeling. For instance, in oil and gas industry, the exploration and production of hydrocarbons now occur in more difficult geological settings; such as in naturally fractured media, in overpressured shale formations, in rubble zones of sub-salt formations, and at great depths. In fractured porous formations, borehole instability has been of major concern due to potential rock movements along fractures at the borehole wall. In the case of shale formations, not only does the state of stress and pressure play a role, but also the properties and interactions between the shale and the drilling fluid.

7. Wellbore/borehole stability

Abstract

The drilling for oil and gas exploration and production under increasingly difficult geological conditions has revealed a need for better understanding of borehole stability issues. It is estimated that wellbore instability results in substantial economic losses of about US$ 8 billion per year worldwide.

8. Stress-dependent permeability

Abstract

Permeability of a rock mass is a physical property of extreme importance in petroleum engineering, civil and environmental engineering, and various areas of geology. Permeability in a fractured porous medium is mainly controlled by the geometry and interconnectionedness of the pores and fractures as well as stress state. Many research efforts have led to the permeability expressions for porous and fractured media. However, most approaches ignored the influences of the pore pressure and stress changes. Various attempts have found that stress-deformation behavior of fractures and pores present in rock masses is a key factor governing rock permeability and fluid flow through the rock masses.

9. Strata failure and mining under surface and ground water

Abstract

Many coal mines are threatened by bodies of water during coal extractions. These bodies of water include rivers, lakes, reservoirs and groundwater. For example, there are about 125 rivers flowing through China's coal fields, and more than 200 coal mines are confronted with the problems of mining under rivers. For groundwater, there are three main possible water disasters affected safety operations of coal mines (Zhang et al. 1997, Peng and Meng 2002): (1) water inrushes from Ordovician limestone underlying the Permo-Carboniferous coal seams in Northern China; (2) water inrushes from low Permian limestone underlying coal seams and from Triassic limestone overlying coal seams of late Permian in Southern China; and (3) water inrushes from Cenozoic porous aquifers in the Yellow River and Huai River alluvial plain areas.

10. Water inrush and mining above confined aquifers

Abstract

In many coal mines the limestone confined aquifers underlie coal seams. During coal extraction from these mines, water inrushes occur frequently with disastrous consequences. The most serious one of possible water disasters affecting the safe operation of coal mines in China is water inrushes from the Ordovician limestone under the Permo-Carboniferous coal seams in Northern China (Zhang and Shen 2004). The Ordovician limestone is a confined karst aquifer containing an abundant supply of water and a very high water pressure. Furthermore, the strata between coal seams and the aquifer are relatively thin varying in thickness from 30 to 60 m. Due to these characteristics of the aquifer, plus mining-induced strata failure and inherent geological structures (such as water-conducting faults, fractures) high pressure groundwater can break through seam floors and burst into mining workings. Therefore, water inrushes from the aquifer occur frequently, and coal mines often suffer from serious water disasters during coal extractions (Peng 1997, 1999). Water inrush incidents have shown that the maximum water inflow in a coal mine has reached as much as 2,053 m³/min, which submerged the mine in a very short time.

11. Stability of underground excavations

Abstract

The closed-form elastic solution for a circle excavation can be obtained in two-dimensional geometry. A circular cross section of a long excavation in a formation subject to biaxial stress is examined, as shown in Fig. 11.1. The biaxial stresses in the far-field of the excavation are assume ed as_σ₀ and kσ₀. The analytical solutions for stress and displacement distributions around the circular opening can be expressed as follows (Brady and Brown 1985).

Backmatter

Titel: Engineering Geology for Underground Rocks
verfasst von: Professor Supping Peng
Dr. Jincai Zhang
Verlag: Springer Berlin Heidelberg
Electronic ISBN: 978-3-540-73295-2
Print ISBN: 978-3-540-73294-5
DOI: https://doi.org/10.1007/978-3-540-73295-2