Large scale in-situ tests on stress and water flow relationships in fractured rock

2012 ◽  
Vol 76 (8) ◽  
pp. 3033-3043 ◽  
Author(s):  
D. Holton ◽  
S. Baxter ◽  
A. R. Hoch

AbstractA range of potential concepts for the geological disposal of high level wastes and spent fuel are being studied and considered in the UK. These include concepts that use bentonite as a buffer material around the waste containers. The bentonite will be required to fulfil certain safety functions, the most important being (1) to protect the waste containers from detrimental thermal, hydraulic, mechanical and chemical processes; and (2) to retard the release of radionuclides from any waste container that fails. The bentonite should have a low permeability and a high sorption capacity.These safety functions could be challenged by certain features, events and processes (FEPs) that may occur during the evolution of the disposal system. A consideration of how these FEPs may affect the safety functions can be used to identify and to prioritize the important areas for research on bentonite. We identify these important areas (which include hydration of compacted bentonite, illitization and erosion of bentonite), and describe how they are being investigated in current international research on bentonite.The Äspö EBS Task Force is a collaborative international project designed to carry out research on bentonite. In 2011, the Nuclear Decommissioning Authority Radioactive Waste Management Directorate joined the EBS Task Force partly to benefit from its collective experience. The work of the EBS Task Force is split into two research subareas: (1) the THM subarea, which includes tasks to understand homogenization of bentonite as it resaturates, to investigate the hydraulic interaction between bentonite and fractured rock, and to model in situ experiments; and (2) the THC subarea, which includes tasks to investigate the issue of understanding transport through bentonite, and to model in situ experiments. In particular, the bentonite rock interaction experiment is a large-scale in situ experiment concerned with understanding groundwater exchange across bentonite rock interfaces, with the objective of establishing better understanding of bentonite wetting. In this paper, we describe our work to model the spatial and temporal resaturation of bentonite buffer in a fractured host rock.


Author(s):  
B. D. Plourde ◽  
J. P. Abraham ◽  
G. S. Mowry ◽  
W. J. Minkowycz

A recent research project has been focused on the design, manufacture, and testing of novel, vertical-axis turbines which can be directly attached to existing structures (such as communication towers) for local power generation, particularly in areas of the world where grid-connected electricity is unavailable. The proposed turbine has undergone a multitude of design stages, including the wing design, prototype fabrication, wind-tunnel testing, and manufacture. This report discusses the initial design process utilized to create the turbine wing. That process relied upon numerical simulations of the unsteady flow patterns which occur when the wing rotates. Results from the simulation were used to modify the wing design and significant improvements in performance were realized. Based on wind-tunnel tests, improvements on the order of 300% were obtained, compared to the initial design. Improvements of this magnitude have allowed the progression from prototype testing to large-scale manufacturing. The simulations allowed the implementation of novel design features such as preferentially deployed vents which allowed an increase of torque and a decrease of transverse loads. Results from the simulation were compared with experimental results obtained from a wind-tunnel test. In addition, data was extracted from an in situ test facility which was installed with wind-speed and data acquisition equipment. It was found that the results of the simulation were in close agreement with both the results from the wind tunnel and the in situ tests. The congruence gave added confidence to the veracity of the simulations.


Author(s):  
Christina Rudolph ◽  
Jürgen Grabe

The application of piles as foundations for offshore wind turbines yields new requirements for the design. Wind and waves induce a cyclic lateral loading on the pile which changes direction corresponding to the meteorological conditions. Cyclic lateral loading on piles results in accumulated displacements, depending on the cyclic load level and load characteristics. The deformation can increase significantly due to a varying loading direction. Under such loading conditions the pile can drift sideways even if the loading is symmetric. Wings attached to the pile shortly below the seabed have been known to reduce deformations on laterally loaded piles as they locally enlarge the diameter on which the soil resistance is activated. They also change the cross-section of the pile from a circular shape to a star-shape. This might reduce the drifting of the pile. A series of large-scale in-situ tests has been carried out in order to identify the effects of changing loading direction as well as the applicability of winged piles to reduce deformations. Two tubular steel piles (one of them equipped with wings) have been installed and subjected to high-cyclic lateral loading from varying directions. In this paper the in-situ tests and their results are presented.


1990 ◽  
Vol 212 ◽  
Author(s):  
B. H. Kjartanson ◽  
M. N. Gray ◽  
B.C.M. Pulles

ABSTRACTAECL Research is carrying out large-scale in situ experiments at its Underground Research Laboratory (URL). The Buffer/Container Experiment is designed principally to investigate the full scale, in situ performance of bentonite-based buffer material in a single emplacement borehole environment. In addition, the response of the rock to excavation and heating will be investigated. The experiment also allows for the development of the technologies needed to demonstrate some of the vault engineering activities proposed in the Canadian nuclear fuel waste disposal concept. These include excavation of large diameter boreholes for waste emplacement and in situ compaction of a bentonite/sand buffer mixture. Although these methodologies developed for the URL have not been optimized for the commercial, full-scale operations needed for a disposal vault, results show that the equipment and methodologies needed for vault operations are a reasonable extrapolation of existing technology.


2021 ◽  
Author(s):  
Diana Avadanii ◽  
Lars Hansen ◽  
Ed Darnbrough ◽  
Katharina Marquardt ◽  
David Armstrong ◽  
...  

<p>The mechanics of olivine deformation play a key role in large-scale, long-term planetary processes, such as the response of the lithosphere to tectonic loading or the response of the solid Earth to tidal forces, and in short-term processes, such as the evolution of roughness on oceanic fault surfaces or postseismic creep within the upper mantle. Many previous studies have emphasized the importance of grain-size effects in the deformation of olivine. However, most of our understanding of the role of grain boundaries in deformation of olivine is inferred from comparison of experiments on single crystals to experiments on polycrystalline samples.</p><p>To directly observe and quantify the mechanical properties of olivine grain boundaries, we use high-precision mechanical testing of synthetic forsterite bicrystals with well characterised interfaces. We conduct nanoindentation tests at room temperature on low-angle (13<sup>o</sup> tilt about [100] on (015)) and high-angle (60<sup>o</sup> tilt about [100] on (011)) grain boundaries. We observe that plasticity is easier to initiate if the grain boundary is within the volume tested. This observation agrees with the interpretation that certain grain-boundary configurations can act as sites for initiating microplasticity.</p><p>As part of continuing efforts, we are also conducting in-situ micropillar compression tests at high-temperature (above 600<sup>o</sup> C) within similar bicrystals. In these experiments, the boundary is contained within the micropillar and oriented at 45<sup>o</sup> to the loading direction to promote shear along the boundary. In these in-situ tests, our hypothesis is that the low-angle grain boundary displays a higher viscosity relative to the high-angle interface. Key advantages of performing in-situ experiments are the direct observation of grain-boundary migration or sliding, simplified kinematics of a single boundary segment, and  potentially changes in style of deformation with different grain-boundary character.</p><p>These small deformation volume experiments allow us to qualitatively explore the differences between the crystal interior and regions containing grain boundaries. Overall, the variation in strain and temperature in our small scale experiments allows the fundamental investigation of the response of well characterised forsterite grain boundaries to deformation. </p>


2010 ◽  
Vol 452-453 ◽  
pp. 225-228
Author(s):  
B. Li ◽  
Y. Jiang

The in-situ tests have been widely used to directly assess the strength and deformability of rock mass, along with which, various numerical approaches were proposed to give rational interpretations to the mechanical phenomenon happening during these tests. In this study, the so-called potential cracks are introduced into DEM model, leading to expanded DEM (EDEM) approach which is capable of simulating the cracking in intact rocks. The EDEM is applied to an in-situ triaixal compression test on a fractured rock sample. The simulation has well represented the failure mode, peak stress and elastic modulus obtained from tests as well as the cracking phenomenon and the slips on fracture planes during the loading process.


2018 ◽  
Vol 23 (suppl_1) ◽  
pp. e16-e16
Author(s):  
Ahmed Moussa ◽  
Audrey Larone-Juneau ◽  
Laura Fazilleau ◽  
Marie-Eve Rochon ◽  
Justine Giroux ◽  
...  

Abstract BACKGROUND Transitions to new healthcare environments can negatively impact patient care and threaten patient safety. Immersive in situ simulation conducted in newly constructed single family room (SFR) Neonatal Intensive Care Units (NICUs) prior to occupancy, has been shown to be effective in testing new environments and identifying latent safety threats (LSTs). These simulations overlay human factors to identify LSTs as new and existing process and systems are implemented in the new environment OBJECTIVES We aimed to demonstrate that large-scale, immersive, in situ simulation prior to the transition to a new SFR NICU improves: 1) systems readiness, 2) staff preparedness, 3) patient safety, 4) staff comfort with simulation, and 5) staff attitude towards culture change. DESIGN/METHODS Multidisciplinary teams of neonatal healthcare providers (HCP) and parents of former NICU patients participated in large-scale, immersive in-situ simulations conducted in the new NICU prior to occupancy. One eighth of the NICU was outfitted with equipment and mannequins and staff performed in their native roles. Multidisciplinary debriefings, which included parents, were conducted immediately after simulations to identify LSTs. Through an iterative process issues were resolved and additional simulations conducted. Debriefings were documented and debriefing transcripts transcribed and LSTs classified using qualitative methods. To assess systems readiness and staff preparedness for transition into the new NICU, HCPs completed surveys prior to transition, post-simulation and post-transition. Systems readiness and staff preparedness were rated on a 5-point Likert scale. Average survey responses were analyzed using dependent samples t-tests and repeated measures ANOVAs. RESULTS One hundred eight HCPs and 24 parents participated in six half-day simulation sessions. A total of 75 LSTs were identified and were categorized into eight themes: 1) work organization, 2) orientation and parent wayfinding, 3) communication devices/systems, 4) nursing and resuscitation equipment, 5) ergonomics, 6) parent comfort; 7) work processes, and 8) interdepartmental interactions. Prior to the transition to the new NICU, 76% of the LSTs were resolved. Survey response rate was 31%, 16%, 7% for baseline, post-simulation and post-move surveys, respectively. System readiness at baseline was 1.3/5,. Post-simulation systems readiness was 3.5/5 (p = 0.0001) and post-transition was 3.9/5 (p = 0.02). Staff preparedness at baseline was 1.4/5. Staff preparedness post-simulation was 3.3/5 (p = 0.006) and post-transition was 3.9/5 (p = 0.03). CONCLUSION Large-scale, immersive in situ simulation is a feasible and effective methodology for identifying LSTs, improving systems readiness and staff preparedness in a new SFR NICU prior to occupancy. However, to optimize patient safety, identified LSTs must be mitigated prior to occupancy. Coordinating large-scale simulations is worth the time and cost investment necessary to optimize systems and ensure patient safety prior to transition to a new SFR NICU.


2021 ◽  
Vol 13 (2) ◽  
pp. 228
Author(s):  
Jian Kang ◽  
Rui Jin ◽  
Xin Li ◽  
Yang Zhang

In recent decades, microwave remote sensing (RS) has been used to measure soil moisture (SM). Long-term and large-scale RS SM datasets derived from various microwave sensors have been used in environmental fields. Understanding the accuracies of RS SM products is essential for their proper applications. However, due to the mismatched spatial scale between the ground-based and RS observations, the truth at the pixel scale may not be accurately represented by ground-based observations, especially when the spatial density of in situ measurements is low. Because ground-based observations are often sparsely distributed, temporal upscaling was adopted to transform a few in situ measurements into SM values at a pixel scale of 1 km by introducing the temperature vegetation dryness index (TVDI) related to SM. The upscaled SM showed high consistency with in situ SM observations and could accurately capture rainfall events. The upscaled SM was considered as the reference data to evaluate RS SM products at different spatial scales. In regard to the validation results, in addition to the correlation coefficient (R) of the Soil Moisture Active Passive (SMAP) SM being slightly lower than that of the Climate Change Initiative (CCI) SM, SMAP had the best performance in terms of the root-mean-square error (RMSE), unbiased RMSE and bias, followed by the CCI. The Soil Moisture and Ocean Salinity (SMOS) products were in worse agreement with the upscaled SM and were inferior to the R value of the X-band SM of the Advanced Microwave Scanning Radiometer 2 (AMSR2). In conclusion, in the study area, the SMAP and CCI SM are more reliable, although both products were underestimated by 0.060 cm3 cm−3 and 0.077 cm3 cm−3, respectively. If the biases are corrected, then the improved SMAP with an RMSE of 0.043 cm3 cm−3 and the CCI with an RMSE of 0.039 cm3 cm−3 will hopefully reach the application requirement for an accuracy with an RMSE less than 0.040 cm3 cm−3.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Sungmin O. ◽  
Rene Orth

AbstractWhile soil moisture information is essential for a wide range of hydrologic and climate applications, spatially-continuous soil moisture data is only available from satellite observations or model simulations. Here we present a global, long-term dataset of soil moisture derived through machine learning trained with in-situ measurements, SoMo.ml. We train a Long Short-Term Memory (LSTM) model to extrapolate daily soil moisture dynamics in space and in time, based on in-situ data collected from more than 1,000 stations across the globe. SoMo.ml provides multi-layer soil moisture data (0–10 cm, 10–30 cm, and 30–50 cm) at 0.25° spatial and daily temporal resolution over the period 2000–2019. The performance of the resulting dataset is evaluated through cross validation and inter-comparison with existing soil moisture datasets. SoMo.ml performs especially well in terms of temporal dynamics, making it particularly useful for applications requiring time-varying soil moisture, such as anomaly detection and memory analyses. SoMo.ml complements the existing suite of modelled and satellite-based datasets given its distinct derivation, to support large-scale hydrological, meteorological, and ecological analyses.


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