scholarly journals Continuous assessment of landslides by measuring their basal temperature

Landslides ◽  
2021 ◽  
Author(s):  
Carolina Seguí ◽  
Manolis Veveakis
Keyword(s):  
Field Data ◽  
Experimental Testing ◽  
Triaxial Tests ◽  
Threshold Values ◽  
Continuous Assessment ◽  
Theoretical Assumption ◽  
Suggested Approach ◽  
Active Landslide ◽  
Rate Controlled ◽  
Band Material

AbstractIn this study, we suggest a temperature-based assessment and mitigation approach for deep-seated landslides that allows to forecast the behavior of the slide and assess its stability. The suggested approach is validated through combined field monitoring and experimental testing of the El Forn landslide (Andorra), whose shear band material is Silurian shales. Thermal and rate controlled triaxial tests have shown that this material is thermal- and rate-sensitive, and in combination with the field data, they validate the theoretical assumption that by measuring the basal temperature of an active landslide, we can quantify and reduce the uncertainty of the model’s parameters, and adequately monitor and forecast the response of the selected deep-seated landslide. The data and results of this letter show that the presented model can give threshold values that can be used as an early-warning assessment and mitigation tool.

Measuring total volumetric strains during triaxial tests on frozen soils: a new approach

1978 ◽  
Vol 15 (1) ◽  
pp. 47-53 ◽  
Author(s):  
M. J. O'Connor ◽  
R. J. Mitchell
Keyword(s):  
Volume Change ◽  
Deformation Rate ◽  
Sample Volume ◽  
Triaxial Tests ◽  
Fluid Level ◽  
Frozen Soils ◽  
New Approach ◽  
Triaxial Cell ◽  
Rate Controlled ◽  
Theoretical Accuracy

A triaxial cell has been modified to permit measurement of volumetric strains during deformation-rate-controlled and stress-controlled triaxial tests on frozen soils. In the system described here, a volume change in the soil sample alters the level of fluid in the triaxial cell. The fluid level can be monitored during the test using a sloping tube volumeter. Theoretical accuracy with this arrangement can exceed 0.1% of the sample volume.

Vibration of a U-shaped steel–concrete composite hollow waffle floor under human-induced excitations

2020 ◽  
Vol 23 (14) ◽  
pp. 2996-3008
Author(s):  
Xi Zhang ◽  
Qing Li ◽  
Yousan Wang ◽  
Qiming Wang
Keyword(s):  
Plate Theory ◽  
Experimental Testing ◽  
Damping Ratio ◽  
Low Frequency ◽  
Threshold Values ◽  
Thin Plate Theory ◽  
Orthotropic Thin Plate ◽  
Floor System ◽  
Vibration Performance ◽  
Position Group

The U-shaped steel–concrete composite hollow waffle floor is an innovative slender large-span floor system, where severe vibration may occur under human-induced excitations. In this research, a theoretical analysis and experimental testing are performed to explore the vibration behaviour of the composite hollow waffle floor. First, the natural frequency formula is proposed based on orthotropic thin plate theory, and the main rigidity calculation for the composite hollow waffle floor is given. Second, the mode shape, frequency and damping ratio of the composite hollow waffle floor are captured by on-site tests and validated by analytical and numerical methods, indicating that the floor has a low-frequency with a low damping ratio. Third, the vibration response of the composite hollow waffle floor is obtained by walking and running tests considering the influence of the frequency, spatial position, group size and route; in addition, the relationships between the values involved in the vibration evaluation are discussed. Finally, the composite hollow waffle floor presents satisfactory vibration performance evaluated by the threshold values among the current codes.

scholarly journals An Experimentally Verified NOx Emission Model for Gas Turbine Combustors

1975 ◽  
Author(s):  
W. S. Y. Hung
Keyword(s):  
Gas Turbine ◽  
Analytical Model ◽  
Field Data ◽  
Experimental Testing ◽  
A Priori ◽  
Water Injection ◽  
Nox Emission ◽  
Nox Emissions ◽  
Emission Model ◽  
Gas Turbine Combustors

An analytical model has been developed to simulate the thermal NOx emission processes in various gas turbine combustors for a variety of fuels. The NOx emissions predicted by the model are in excellent agreement with available laboratory and field data. Its capability to simulate the water injection process accurately has been demonstrated previously. Comprehensive understanding of the NOx emission processes in gas turbine combustors has been gained through the current analytical studies. NOx emissions as influenced by ambient humidity, changes in combustor geometry, type of fuel used and changes in operating parameters can now be evaluated quantitatively through a priori prediction and have been verified by available laboratory and field data. The analytical model has also been demonstrated to be a powerful guidance tool in directing the experimental testing program in an effort to reduce NOx emissions from gas turbine combustors.

scholarly journals Experimental Testing and Numerical Modelling of Mechanical Behaviors of Silty Clay under Freezing-Thawing Cycles

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Tianfei Hu ◽  
Dawei Liu ◽  
Hui Wu
Keyword(s):  
Numerical Modelling ◽  
Experimental Testing ◽  
Axial Strain ◽  
Volumetric Strain ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Silty Clay ◽  
Test Results ◽  
Mechanical Behaviors ◽  
Physical Weathering

Seasonal freezing-thawing cycle is one of the most common physical weathering processes in cold regions, which can significantly affect the mechanical behaviors of soil. In this paper, a series of freezing-thawing (F-T) cycle and consolidated drained triaxial tests have been carried out on silty clay samples collected from Tibetan Plateau. To do so, a modified numerical model was developed taking into F-T effect. Test results showed that the stress-strain curves of original soil specimens presented strain hardening characteristics, accompanied with shear shrinkage. In F-T experienced specimens, volumetric strain in triaxial loading stage was gradually increased, while failure strength was decreased. Elliptic and parabolic functions were selected in numerical modelling to describe volume and shear yield surfaces on a p-q plane, respectively. Moreover, a double-yield surface constitutive model was developed to describe relationships among deviatoric stress, axial strain, and volumetric strain. Furthermore, equations for model parameters with the number of F-T cycles as variable were derived based on the triaxial test results which were then substituted into the established model to take into account the effects of F-T cycles. Finally, numerical results were validated with experimental findings.

Empirical and theoretical assessment of the wind induced error of rain measurement

1998 ◽  
Vol 37 (11) ◽  
pp. 171-178 ◽  
Author(s):  
B. Sevruk ◽  
V. Nespor
Keyword(s):  
Wind Speed ◽  
Field Data ◽  
Threshold Value ◽  
Threshold Values ◽  
Correction Formula ◽  
Empirical Correction ◽  
Independent Variable ◽  
Theoretical Assessment ◽  
Comparison Measurements ◽  
Rain Measurement

The computational fluid dynamics and the simulation of precipitation trajectories was applied to assess the wind induced error of precipitation measurements using the Hellmann gauge. The results agree well with the empirical correction formula for the same gauge type derived from field data obtained from inter comparison measurements of paired Hellmann elevated and pit gauges in Les Avants (982m asl), Switzerland. This means that correction procedures can be derived for any type of gauge using the theoretical approach instead of the empirical one. The computational and empirical results fit a model which uses the intensity of rain as an independent variable and produces a set of one parameter curves (wind speed) with increasing threshold value of intensity for increasing wind speed. Below the threshold values the wind-induced error increases quickly with decreasing intensity of precipitation; above it the increase is slow.

Identify Carbonate Lithology by Fuzzy Mathematics

2014 ◽  
Vol 912-914 ◽  
pp. 532-535
Author(s):  
Wei Fu Liu ◽  
Shuang Long Liu ◽  
Li Xin Sun
Keyword(s):  
Carbonate Rocks ◽  
Field Data ◽  
Fuzzy Mathematics ◽  
Core Analysis ◽  
Threshold Values ◽  
Success Ratio ◽  
Carbonate Formation ◽  
Lithology Identification ◽  
Set Up

In accordance with low success ratio of lithology identification in carbonate formation, a made of Identifying lithology of carbonate rocks through fuzzy mathematics has set up. 8 logging parameters reflecting lithology of carbonate rocks were selected and threshold values were determined. Lithologies of carbonate rocks were classified by using this identification mode and maximum subordination principle. Using field data identified 10 types of carbonate rocks, and they were compared with the result of core analysis, showing 85 % consistency. Therefore this method has higher accuracy for identification of carbonate lithology, and is quite promising in geological application.

scholarly journals Comparative analysis of experimental testing procedures for the elicitation of rescue actions in ants

2021 ◽  
Author(s):  
Filip Turza ◽  
Krzysztof Miler
Keyword(s):  
Comparative Analysis ◽  
Field Data ◽  
Experimental Testing ◽  
Natural Setting ◽  
Body Parts ◽  
Testing Procedures ◽  
Comparison Of Results ◽  
Different Types ◽  
Rescue Behaviour ◽  
Formica Cinerea

Abstract Rescue behaviour is observed when one individual provides help to another individual in danger. Most reports of rescue behaviour concern ants (Formicidae), in which workers rescue each other from various types of entrapment. Many of these entrapment situations can be simulated in the laboratory using an entrapment bioassay, in which ants confront a single endangered nest mate entrapped on a sandy arena by means of an artificial snare. Here, we compared numerous characteristics of rescue actions (contact between individuals, digging around the entrapped individual, pulling at its body parts, transport of the sand covering it and biting the snare entrapping it) in Formica cinerea ants. We performed entrapment tests in the field and in the laboratory, with the latter under varying conditions in terms of the number of ants potentially engaged in rescue actions and the arena substrate (marked or unmarked by ants’ pheromones). Rescue actions were more probable and pronounced in the field than in the laboratory, regardless of the type of test. Moreover, different test types in the laboratory yielded inconsistent results and showed noteworthy variability depending on the tested characteristic of rescue. Our results illustrate the specifics of ant rescue actions elicited in the natural setting, which is especially important considering the scarcity of field data. Furthermore, our results underline the challenges related to the comparison of results from different types of entrapment tests reported in the available literature. Additionally, our study shows how animal behaviour differs in differing experimental setups used to answer the same questions.

Soil threshold values of total and available cadmium for vegetable growing based on field data in Guangdong province, South China

2013 ◽  
Vol 93 (8) ◽  
pp. 1967-1973 ◽  
Author(s):  
Fang Fang Sun ◽  
Fu Hua Wang ◽  
Xu Wang ◽  
Wu He ◽  
Dian Wen ◽  
...  
Keyword(s):  
South China ◽  
Field Data ◽  
Guangdong Province ◽  
Threshold Values

Multicriteria Decision Analysis for Wave Power Technology in Canada

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Joshua R. Monds
Keyword(s):  
Power Generation ◽  
Decision Analysis ◽  
Experimental Testing ◽  
Multicriteria Decision Analysis ◽  
Wave Power ◽  
Maturity Stage ◽  
Threshold Values ◽  
Multicriteria Decision ◽  
Ranking Order ◽  
Wave Power Generation

Three individual wave power generation technologies were studied and evaluated using multicriteria decision analysis through the use of the PROMETHEE method. To evaluate the three technologies, data were collected from previously performed experimental testing on the performance of each wave power generation technology. These data were used to feed into seven different criteria; namely the capacity factor, rated power, capital cost, operation and maintenance (O&M) costs, cost of electricity (COE) for a 10 year payback, maturity, and survivability. The associated data and criteria were used to determine the optimal technology. The results from the Decision Lab modeling ranked the Wave Dragon, AquaBuOY, and Pelamis technologies as 1, 2, and 3, respectively, for all three locations: Tofino/Ucluelet, Hibernia Oil Platform, and St. John's, Newfoundland. A sensitivity analysis of the threshold values determined for the baseline modeling indicated that the original ranking was essentially unaffected when the threshold values were modified (increased and decreased). The weights of the criterion were individually adjusted to evaluate any change in ranking order. A sizable increase in weighting of greater than 40% of any one criterion (while the others were weighed equally) resulted in a change of the overall ranking order of the three technologies. Final weightings on each of the criterion were assigned with preference on rated power, COE, and maturity stage. All other criteria were weighted equally and like the baseline modeling output, the results of the model ranked Wave Dragon, AquaBuOY, and Pelamis from most favorable to least favorable for all three of the locations analyzed.

scholarly journals Simulations of Fine-Meshed Biaxial Tests with Barodesy

Geosciences ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 20
Author(s):  
Gertraud Medicus ◽  
Barbara Schneider-Muntau
Keyword(s):  
Shear Band ◽  
Void Ratio ◽  
Experimental Testing ◽  
Experimental Studies ◽  
Triaxial Tests ◽  
Biaxial Test ◽  
Average Response ◽  
Stress Strain ◽  
Ratio Distribution ◽  
Biaxial Tests

Recent experimental studies showed that shear band development starts at the beginning of triaxial tests. In experimental testing, it is impossible to obtain a soil sample with a homogeneous void ratio. Therefore, a homogeneous deformation, i.e., an element test, is questionable well before the peak. In this article we carry out finite element simulations of fine-meshed biaxial tests with the constitutive model barodesy, where the stress rate is formulated as a function of stress, stretching and void ratio. The initial void ratio in the simulations is normally distributed over all elements in a narrow range. In this article, we evaluate the pre-peak shear band development. We further compare stress paths and stress-strain curves of the biaxial test of relevant elements (e.g., in- and outside the shear band) with the results of the average response of all elements. We show how the response in an element test differs from the average response of the fine-meshed test. We present the resulting potential for understanding (early) shear band development and stress-strain behaviour in a biaxial test: The inhomogeneous void ratio distribution in a sample favours early shear band development. This effect is modelled with barodesy. The obtained stress paths and stress-strain curves show that the maximum deviatoric stress is higher in the element test than it is in the average response of the fine-meshed test.

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