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Collaborating Authors
Reservoir Description and Dynamics
ABSTRACT Two-dimensional numerical modelling of the influence of joint orientation on the Uniaxial Compressive Strength (UCS) of singly- and multiply-jointed cylindrical rock samples was performed using models with slenderness (length/diameter) values of 2 and 4. For steep joint orientations, the more slender models were found to produce smaller UCS values when compared to the less slender models in the case of the singly-jointed rock specimens. This observation was related to the need for more significant intact material rupture to accommodate sliding failure on the joint for the case of the less slender specimen models. When recommendations for specimen slenderness outlined in popular standards for UCS testing are adopted one should take care to ensure the slenderness values used do not place restrictions on the mechanisms by which failure can occur. Such restrictions are likely to cause overestimation of strength estimates for jointed rock obtained from UCS testing and could introduce significant risk in engineering design. No dependence on specimen slenderness was observed for the multiply-jointed specimen models. This appears to be related to the wider deformation zone available for sliding failure in the multiply-jointed models, which circumvents the need for significant intact material rupture in the failure process. The use of sufficiently slender rock specimens may not be required for realistic UCS values to be obtained for jointed rock in cases where the rock has multiple parallel joints and sufficiently small joint spacing.
ABSTRACT The deformation behavior of Tage Tuff during desiccation was investigated. Strain as well as compressional (P) and shear (S) wave velocities were measured concurrently in a set of cylindrical Tage Tuff specimens cored across and along the bedding plane. Two saturated specimens were prepared in one-dimensional drying conditions (50°C, 50% relative humidity) at a time. The strain and weight of one specimen was automatically measured using strain rosettes and an electronic scale. The ultrasonic wave velocity and weight of the second specimen were measured using transducers and an electronic scale and manually recorded. When the degree of saturation decreased by no more than 70%, P wave velocity decreased with two distinct trends depending on the two main textural directions. However, S wave velocity and strain remained constant. This was due to the inter-bedding and intra-bedding pore water characteristics within the specimen. When the saturations dropped below 30%, both velocities increased with a decrease in strains due to the desiccation-driven hardening. The relationship of incremental P wave velocity and incremental volumetric strain followed the shape of a parabola which can explain by the theories of linear poroelasticity. Different height specimens (5cm and 3cm) exhibit similar strain magnitude and wave velocity behavior.
- Geology > Geological Subdiscipline > Geomechanics (0.47)
- Geology > Rock Type > Sedimentary Rock (0.30)
ABSTRACT Various factors such as physical and geometrical properties of pressure cell, properties of surrounding media and installation techniques seriously affect the accuracy of total pressure measurement within soil or concrete structure. In this study a numerical code was used to simulate some of factors affecting calibration coefficient and steps of installation in soil and tunnel concrete lining, for this purpose more than 1200 elastic 3D analysis for various installation situations performed. The results show for pressure cell in soils, geometric factors and compaction quality of the surrounding material greatly affect on the precision of measurement and for pressure cells that are installed in tunnel concrete lining, the most important factor in the installation method, is the place that pressure cell is installed in respect to the stress concentration.
- North America > United States (0.28)
- Asia > Middle East > Iran (0.16)
- Data Science & Engineering Analytics > Information Management and Systems (0.85)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.47)
Anisotropy of Mechanical Properties in Kimachi Sandstone, Japan
Parka, Hyuck (National Institute of Advanced Industrial Science and Technology) | Takahashia, Manabu (National Institute of Advanced Industrial Science and Technology) | Fujii, Yukiyasu Fujii (Fukada Geological Institute) | Takemura, Takato (Fukada Geological Institute) | Ito, Kazumasa (National Institute of Advanced Industrial Science and Technology)
ABSTRACT We carried out P wave velocity tests and uniaxial compression tests in various directions to investigate the anisotropy of mechanical properties of sedimentary rock. First of all, two plate shaped blocks were prepared which are vertical and parallel to the bedding plane. Twelve cylindrical specimens were prepared for each block in different directions (every 30 degree, size: f 50 mm, h 100 mm). Elastic wave velocities and uniaxial compression strength were carefully measured. The anisotropies of P wave velocity were insignificant for both blocks. However, anisotropy of uniaxial compression strength was noticeably high on the horizontal block. The changes of Young's modulus anisotropies on both block specimens were also investigated for different stress levels (10, 30%, 50%, 70% and 90% of uniaxial compression strength). The experimental results indicate that the anisotropy of mechanical properties in Kimachi sandstone is strongly related with the sedimentation environment. However, the directions of bedding plane and cross-lamination were not influential to the anisotropy of mechanical properties.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.65)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.84)
ABSTRACT An improved St. Venant body satisfying generalized plastic potential theory is proposed in this paper to describe the hardening and softening properties of surrounding rockmass of underground engineering. To generalize the new one-dimensional model into three-dimension, the threedimensional constitutive relations of the improved St. Venant body based on generalized plasticity potential theory are deduced first, and the new three-dimensional model subsequently. Numerical simulation of triaxial compression tests validate the new rheology model. The new rheology model can be applied in the research of damaged zone revolution of surrounding rock in underground engineering.
- Reservoir Description and Dynamics > Reservoir Simulation (0.86)
- Reservoir Description and Dynamics > Reservoir Characterization (0.71)
- Well Completion > Completion Installation and Operations > Perforating (0.61)
ABSTRACT In-situ stresses are one of the most important elements for the design and stability assessment of rock engineering structures and earthquake science. Many in-situ stress inference and measurements techniques are devised and they are broadly classified into direct or indirect techniques. Drilling and blasting technique is widely used as an excavation technique in rock engineering practice. The experiments on specimens clearly indicated that the fracture zones around the blasthole was larger in the direction of the maximum load. Some parts of the blastholes remain following blasting. The author proposes a method how to infer the in-situ stresses from the damage zones around the blastholes in this article and it is named as the blasthole-damage method. The fundamentals of this method are described and it is applied to several sites where in-situ stress states are obtained by using direct or other indirect techniques. The inferences are compared with measurements and the validity of the method are discussed in view of the measurements or inferences from other methods.
- Asia > Japan (1.00)
- Asia > Middle East > Turkey (0.48)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.93)
ABSTRACT The importance of rock mechanics associated with geological storage of CO2 (GCS) is now widely recognized among GCS stakeholders, especially with respect to the potential for triggering notable (felt) seismic events and how such events could impact the long-term integrity of a CO2 repository (as well as how it could impact the public perception of GCS). To date, no notable seismic event has been reported from any of the current CO2 storage projects, although unfelt microseismic activities have been detected by geophones. However, potential future commercial GCS operations from large power plants will require injection at a much larger scale. For such large-scale injections, a staged, learn-as-you-go approach is recommended, involving a gradual increase of injection rates combined with continuous monitoring of geomechanical changes, as well as siting beneath a multiple layered overburden for multiple flow barrier protection, should an unexpected deep fault reactivation occur.
- Africa > Middle East > Algeria (0.29)
- North America > United States > California (0.28)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.69)
- Africa > Middle East > Algeria > Tamanrasset Province > Ahnet-Timimoun Basin > Krechba Field (0.99)
- Africa > Middle East > Algeria > Ghardaia Province > Ahnet-Timimoun Basin > Krechba Field (0.99)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Health, Safety, Environment & Sustainability > Sustainability/Social Responsibility > Sustainable development (1.00)
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