Abstract
Physical properties are the property of a rock after being tasted without damaging the rock. This research aims to describe the physical properties of rocks in Blawan-Ijen, including rock ...texture, rock density and rock porosity. The method of collecting data is carried out directly, namely conducting direct research in the field and indirect research by conducting library research. The physical properties of the rocks in Blawan-Ijen have a smooth and rough texture, holocrystalline, light and dark colors, and compact. The density value is relatively high, so it has a fairly high density and resistance. In contrast, the porosity value of the rocks in Blawan-Ijen has three categories: poor porosity, very poor porosity, and high porosity. The texture of the rocks in Blawan-Ijen is smooth, holocrystalline, has small cavities and dark in color.
The SuperCam instrument suite provides the Mars 2020 rover, Perseverance, with a number of versatile remote-sensing techniques that can be used at long distance as well as within the robotic-arm ...workspace. These include laser-induced breakdown spectroscopy (LIBS), remote time-resolved Raman and luminescence spectroscopies, and visible and infrared (VISIR; separately referred to as VIS and IR) reflectance spectroscopy. A remote micro-imager (RMI) provides high-resolution color context imaging, and a microphone can be used as a stand-alone tool for environmental studies or to determine physical properties of rocks and soils from shock waves of laser-produced plasmas. SuperCam is built in three parts: The mast unit (MU), consisting of the laser, telescope, RMI, IR spectrometer, and associated electronics, is described in a companion paper. The on-board calibration targets are described in another companion paper. Here we describe SuperCam’s body unit (BU) and testing of the integrated instrument.
The BU, mounted inside the rover body, receives light from the MU via a 5.8 m optical fiber. The light is split into three wavelength bands by a demultiplexer, and is routed via fiber bundles to three optical spectrometers, two of which (UV and violet; 245–340 and 385–465 nm) are crossed Czerny-Turner reflection spectrometers, nearly identical to their counterparts on ChemCam. The third is a high-efficiency transmission spectrometer containing an optical intensifier capable of gating exposures to 100 ns or longer, with variable delay times relative to the laser pulse. This spectrometer covers 535–853 nm (
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7070
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Raman shift relative to the 532 nm green laser beam) with
12
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full-width at half-maximum peak resolution in the Raman fingerprint region. The BU electronics boards interface with the rover and control the instrument, returning data to the rover. Thermal systems maintain a warm temperature during cruise to Mars to avoid contamination on the optics, and cool the detectors during operations on Mars.
Results obtained with the integrated instrument demonstrate its capabilities for LIBS, for which a library of 332 standards was developed. Examples of Raman and VISIR spectroscopy are shown, demonstrating clear mineral identification with both techniques. Luminescence spectra demonstrate the utility of having both spectral and temporal dimensions. Finally, RMI and microphone tests on the rover demonstrate the capabilities of these subsystems as well.
The aim of this research is to develop new intelligent prediction models for estimating the tunnel boring machine performance (TBM) by means of the rate pf penetration (PR). To obtain this aim, the ...Pahang-Selangor Raw Water Transfer (PSRWT) tunnel in Malaysia was investigated and the data collected along the tunnel and generated in the laboratory via rock tests to be used for the proposed models. In order to develop relevant models, rock properties including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), rock quality designation (RQD), rock mass rating (RMR), weathering zone (WZ), and also machine parameters including thrust force (TF) and revolution per minute (RPM) were obtained and then, the dataset composed of both rock and machine parameters were established. After that, using the established database consisting of 1286 datasets, two hybrid intelligent systems namely particle swarm optimization (PSO)-artificial neural network (ANN) and imperialism competitive algorithm (ICA)-ANN and also simple ANN model were developed for predicting the TBM penetration rate. Further, developed models were compared and the best model was chosen among them. To compare the obtained results from the models, several performance indices i.e. coefficient of determination (R2), root mean square error (RMSE) and variance account for (VAF) were computed. It is found that the hybrid models including ICA-ANN and PSO-ANN having determination coefficients of 0.912 and 0.905 respectively for testing data as that of the simple ANN model are 0.666. More, the RMSE (0.034; 0.035) and VAF (90.338; 91.194) of hybrid models are also higher than these of simple ANN model (0.071; 66.148) respectively. Concluding remark is that the hybrid intelligent models are superior in comparison with simple ANN technique.
To define the filtration properties of rocks, various physicochemical methods are used, among which laboratory studies can be distinguished 1, 2. Determination of permeability in laboratory ...conditions is the main physical and technical study of the filtration properties of rocks.
A propagating fluid driven fracture in a rock mass is expected to interact with geological interfaces on a wide variety of length scales. The vertical growth of hydraulic fractures in layered rocks ...is of pivotal importance for the successful stimulation in reservoir development. In this study, 2D discrete element modeling is used to investigate the influence of the stiffness and toughness ratio, as well as stress contrast between layers on the hydraulic fracture height growth. In particular, the ultimate goal is to better understand mechanisms of the fracture height containment by contrasts of different rock properties and to quantitatively determine which parameters provide a stronger influence. In addition, the analysis is performed in the context of hydraulic fracture regimes, whereby the dominant dissipation mechanism in the system can either be associated with fracture toughness or viscous fluid flow. As a starting point, we investigated the propagation of a plane strain hydraulic fracture from a low stiffness layer to a high stiffness layer and vice versa, while keeping the stress constant. The influence of stress on hydraulic fracture propagation in layered rocks is investigated afterwards. The numerical results demonstrate that the hydraulic fracture can either directly pass through the geological interface, be arrested at the interface, or stop before reaching the interface. The interface itself is assumed to be perfectly bonded, therefore no slippage is considered. Ability of the hydraulic fracture to approach the interface is first determined by the elastic modulus ratio of the two adjacent layers. Once reached the interface, the further growth is then affected by the toughness ratio between the layers. After that, if the fracture crosses the interface, then it is affected by the stress contrast. The propagation regime has an important influence on the fracture propagation in layered rocks. If the propagation regime is closer to the viscosity dominated, the hydraulic fracture is likely to cross the interface. In contrast, it is more difficult for a fracture to cross the barrier if the propagation regime is near the toughness dominated. A map of fracture crossing behavior versus propagation regime and contrast in properties has been constructed, that can be used to quantify strength of mechanical barriers and to deduce hydraulic fracture height growth behavior for various scenarios.
For Brazil, a country frequented by droughts and whose rural inhabitants largely depend on groundwater, reliance on isotope for its monitoring, though accurate, is expensive and limited in spatial ...coverage. We exploit total water storage (TWS) derived from Gravity Recovery and Climate Experiment (GRACE) satellites to analyse spatial-temporal groundwater changes in relation to geological characteristics. Large-scale groundwater changes are estimated using GRACE-derived TWS and altimetry observations in addition to GLDAS and WGHM model outputs. Additionally, TRMM precipitation data are used to infer impacts of climate variability on groundwater fluctuations. The results indicate that climate variability mainly controls groundwater change trends while geological properties control change rates, spatial distribution, and storage capacity. Granular rocks in the Amazon and Guarani aquifers are found to influence larger storage capability, higher permeability (>10-4 m/s) and faster response to rainfall (1 to 3months' lag) compared to fractured rocks (permeability <10-7 m/s and lags > 3months) found only in Bambui aquifer. Groundwater in the Amazon region is found to rely not only on precipitation but also on inflow from other regions. Areas beyond the northern and southern Amazon basin depict a ‘dam-like’ pattern, with high inflow and slow outflow rates (recharge slope > 0.75, discharge slope < 0.45). This is due to two impermeable rock layer-like ‘walls' (permeability <10-8 m/s) along the northern and southern Alter do Chão aquifer that help retain groundwater. The largest groundwater storage capacity in Brazil is the Amazon aquifer (with annual amplitudes of > 30cm). Amazon's groundwater declined between 2002 and 2008 due to below normal precipitation (wet seasons lasted for about 36 to 47% of the time). The Guarani aquifer and adjacent coastline areas rank second in terms of storage capacity, while the northeast and southeast coastal regions indicate the smallest storage capacity due to lack of rainfall (annual average is rainfall <10cm).
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•Groundwater storage changes estimated from GRACE link to geological properties.•Rock properties control groundwater distribution, flow rate and storage capacity.•The Amazon area has the largest groundwater change as well as groundwater storage.•The dam pattern in the Amazon has groundwater inflow rate>0.75 and <0.45 outflow rate.•Wet seasons in the Amazon region only occupy about only 36 to 47 months.
Stress conditions around deep underground mine openings can significantly influence rock fragmentation and stability, and thus the cuttability of the targeted rock. In this study, rock breakage ...experiments and associated regression analyses indicate nonlinear rock cuttabilities (decreasing followed by increasing) with increases in the differences between biaxial confining stresses and the values of uniaxial confining stresses. Rock breakages were found to be efficient and safe under low and no-stress conditions that require low indentation force and depth, cutting work and specific energy to completely split the rock wtih no rockburst risk. Stress concentration initially impeded rock breakage, although high uniaxial stress improved rock cuttability. Inducing high stress to fracture the rock and produce an excavation damage zone (EDZ) via stress release effectively transformed the stress condition into low confining stress or even the stress-free condition, improving rock cuttability significantly and preventing rockburst. Mining of rock in the EDZ around the pillar could be efficient, cost-effective and safe when using roadheaders, which showed high cutting efficiencies, low pick wear failures, high machine stabilities and no rockbursts. In addition, a binary linear regression model was proposed to determine the thickness variation of the EDZ correlated with the excavation span and a coupled index of rock properties and buried depth of opening. The results indicated that the thickness of the EDZ increases with increases in the buried depth of the opening, which can improve the applicability of non-explosive mechanized mining in deep mines.
The response of crustal rock to stresses is challenging to estimate yet vital for determining risks from events such as earthquakes. Moore et al. take advantage of the recent Mw 7.1 Kumamoto ...earthquake in Japan to determine the rheology of crustal rocks in the region. The observed inversion of the crustal strain rates demonstrates that certain areas have stiff rock and others (e.g., under the Aso volcanic complex) have much weaker rock. The results match up with expectations, which means that the method can successfully measure rock properties over a wide range of strength and large spatial and temporal scales. Science, this issue p. 163 The deformation of mantle and crustal rocks in response to stress plays a crucial role in the distribution of seismic and volcanic hazards, controlling tectonic processes ranging from continental drift to earthquake triggering. However, the spatial variation of these dynamic properties is poorly understood as they are difficult to measure. We exploited the large stress perturbation incurred by the 2016 earthquake sequence in Kumamoto, Japan, to directly image localized and distributed deformation. The earthquakes illuminated distinct regions of low effective viscosity in the lower crust, notably beneath the Mount Aso and Mount Kuju volcanoes, surrounded by larger-scale variations of viscosity across the back-arc. This study demonstrates a new potential for geodesy to directly probe rock rheology in situ across many spatial and temporal scales.
Abstract Characterizing rock proprieties is crucial in the oilfield to evaluate hydrocarbon reserves. Several studies showed a high correlation between rock properties and textures. Therefore, we ...propose integrating texture information in the images to identify precisely the most representative textures in highly heterogeneous rocks to estimate their properties. First, we implemented a steerable pyramid decomposition to extract the texture features. Then, those parameters were used as input for the Self-organizing map to classify the textures. Finally, by applying several models and comparing their results, we suggested the best approach to implement for texture classification.
Geotechnical characterization of a project site for engineering applications is indispensable in engineering geology and geotechnical engineering, and there are many unavoidable variabilities and ...uncertainties during characterization of a project site. Different variabilities and uncertainties usually are lumped together and observed as the total variability, which includes both the actual variability of soil and rock properties and other knowledge uncertainties, such as measurement errors and statistical uncertainty. It is the actual variability, not the total variability, which affects directly the observed performance (i.e., actual response) of geotechnical and geological systems and is of primary interest in site characterization. This paper aims to consolidate recent advancement in Bayesian studies in site characterization and develops a Bayesian inverse analysis framework for direct quantification of the actual variability of various soil and rock properties. To facilitate development of the framework, the procedure of geotechnical site characterization is revisited from a Bayesian perspective, and the occurrence and propagation of inherent variability, statistical uncertainty, measurement errors, and transformation uncertainty during characterization of a project site are mapped explicitly to different stages in site investigation. Based on the mapping, a robust framework is developed that streamlines the formulation of likelihood functions for various soil and rock properties when estimated using different field or laboratory tests, leading to a streamlined process for applications of the proposed Bayesian framework to different site characterization problems. Application examples are provided to illustrate the implementation and step-by-step procedures of the proposed Bayesian framework.
•Bayesian inverse analysis model is developed for quantifying actual variability of geomaterial.•Occurrence and propagation of uncertainties are mapped to steps in site characterization.•Formulation of likelihood functions is streamlined for different properties.•Implementation procedures are illustrated through examples.
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