Abstract
In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. The productions (and thus the dimensions) of the excavating equipment range from mm3/sec - cm3/sec to m3/sec. In oil drilling layers with a thickness of a magnitude of 0.2 mm are cut, while in dredging this can be of a magnitude of 0.1 m with cutter suction dredges and meters for clamshells and backhoe’s. Some equipment is designed for dry soil, while others operate under water saturated conditions. Installed cutting powers may range up to 10 MW. For both the design, the operation and production estimation of the excavating equipment it is important to be able to predict the cutting forces and powers. After the soil has been excavated it is usually transported hydraulically as a slurry over a short (TSHD’s) or a long distance (CSD’s) or mechanically. Estimating the pressure losses and determining whether or not a bed will occur in the pipeline is of great importance.
Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In TSHD’s the soil has to settle during the loading process, where also sedimentation and erosion will be in equilibrium. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior.
This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, atmospheric rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. The failure mechanism of sand, dry and water saturated, is the so called Shear Type. The failure mechanism of clay is the so called Flow Type, but under certain circumstances also the Curling Type and the Tear Type are possible. Rock will usually fail in a brittle way. This can be brittle tensile failure, the Tear Type for small blade angles, but it can also be brittle shear failure, which is of the Shear Type of failure mechanism for larger blade angles. For practical cutting angles in dredging a combination may occur, the Chip Type. Under hyperbaric conditions rock may also fail in a more apparent ductile way according to the Flow Type or Crushed Type of failure mechanism. This is also called cataclastic failure.
For each case considered, the equations/model for the cutting forces, power and specific energy are given. The models are verified with laboratory research, mainly at the Delft University of Technology, but also with data from literature.
Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In TSHD’s the soil has to settle during the loading process, where also sedimentation and erosion will be in equilibrium. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior.
This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, atmospheric rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. The failure mechanism of sand, dry and water saturated, is the so called Shear Type. The failure mechanism of clay is the so called Flow Type, but under certain circumstances also the Curling Type and the Tear Type are possible. Rock will usually fail in a brittle way. This can be brittle tensile failure, the Tear Type for small blade angles, but it can also be brittle shear failure, which is of the Shear Type of failure mechanism for larger blade angles. For practical cutting angles in dredging a combination may occur, the Chip Type. Under hyperbaric conditions rock may also fail in a more apparent ductile way according to the Flow Type or Crushed Type of failure mechanism. This is also called cataclastic failure.
For each case considered, the equations/model for the cutting forces, power and specific energy are given. The models are verified with laboratory research, mainly at the Delft University of Technology, but also with data from literature.
| Original language | English |
|---|---|
| Place of Publication | Amsterdam, The Netherlands |
| Publisher | IOS Press |
| Number of pages | 710 |
| Volume | 1 |
| Edition | 3 |
| ISBN (Electronic) | 978-94-6186-539-7 |
| ISBN (Print) | 978-94-6186-537-3 |
| Publication status | Published - 2015 |
Publication series
| Name | |
|---|---|
| Publisher | Delft University Press / IOS Press |
Bibliographical note
Dr.ir. Sape A. Miedema (November 8th 1955) obtained his M.Sc. degree in Mechanical Engineering with honours at the Delft University of Technology (DUT) in 1983. He obtained his Ph.D. degree on research into the basics of soil cutting in relation with ship motions, in 1987. From 1987 to 1992 he was Assistant Professor at the chair of Dredging Technology. In 1992 and 1993 he was a member of the management board of Mechanical Engineering & Marine Technology of the DUT. In 1992 he became Associate Professor at the DUT with the chair of Dredging Technology. From 1996 to 2001 he was appointed Head of Studies of Mechanical Engineering and Marine Technology at the DUT, but still remaining Associate Professor of Dredging Engineering. In 2005 he was appointed Head of Studies of the MSc program of Offshore & Dredging Engineering and he is also still Associate Professor of Dredging Engineering. In 2013 he was also appointed as Head of Studies of the MSc program Marine Technology of the DUT.Dr.ir. S.A. Miedema teaches (or has taught) courses on soil mechanics and soil cutting, pumps and slurry transport, hopper sedimentation and erosion, mechatronics, applied thermodynamics related to energy, drive system design principles, mooring systems, hydromechanics and mathematics. He is (or has been) also teaching at Hohai University, Changzhou, China, at Cantho University, Cantho Vietnam, at Petrovietnam University, Baria, Vietnam and different dredging companies in the Netherlands and the USA.
His research focuses on the mathematical modeling of dredging systems like, cutter suction dredges, hopper dredges, clamshell dredges, backhoe dredges and trenchers. The fundamental part of the research focuses on the cutting processes of sand, clay and rock, sedimentation processes in Trailing Suction Hopper Dredges and the associated erosion processes. Lately the research focuses on hyperbaric rock cutting in relation with deep sea mining and on hydraulic transport of solids/liquid settling slurries.
Keywords
- Sand Cutting, Clay Cutting, Rock Cutting