Full-scale field studies of the dynamic response of piles embedded in partially frozen soils

1991 ◽  
Vol 28 (5) ◽  
pp. 708-718 ◽  
Author(s):  
Hans Vaziri ◽  
Yingcai Han
Keyword(s):  
Dynamic Response ◽  
Soil Layer ◽  
Field Measurements ◽  
Field Studies ◽  
Full Scale ◽  
Frozen Soil ◽  
Field Observations ◽  
Practical Applications ◽  
Order Of Magnitude ◽  
Full Scale Tests

The influence of a frozen soil layer on the dynamic response of full-scale concrete piles subjected to strong horizontal excitation was studied. The study undertaken compares the field observations against the theoretical predictions and provides an insight into the role of the yielded zone (boundary zone) in theoretically matching the field observations. The field measurements are used to postulate empirical relationships that can be used under practical conditions to estimate the magnitude of soil separation around piles embedded in cohesive soils as a function of the maximum vibration amplitude. The tests performed indicate that the presence of a frozen soil layer, even at a modest thickness of less than 0.5 m, can significantly influence the dynamic response of piles; the horizontal stiffness of the pile was increased by one order of magnitude, and its resonant frequency was increased by a factor of four compared to the situation with no frozen soil layer. The qualitative and quantitative findings from this study are considered to have practical applications in the design of piles under similar conditions as well as in providing a field validation of the theoretical solutions that have been developed for analyzing the dynamic response of piles. Key words: dynamics, vibration, piles, full-scale tests, frozen soil, modelling, resonance, soil separation, soil yielding.

Propagation characteristics of vibrations induced by heavy-haul trains in a loess area of the North China Plains

2018 ◽  
Vol 25 (4) ◽  
pp. 882-894 ◽  
Author(s):  
Jie Dong ◽  
Yue Yang ◽  
Zhi-Hui Wu
Keyword(s):  
Soil Layer ◽  
Three Dimensional ◽  
Field Measurements ◽  
Frozen Soil ◽  
Three Dimensional Model ◽  
Vibration Acceleration ◽  
Mean Values ◽  
Loess Area ◽  
The North ◽  
Heavy Haul

To study heavy train-related vibration, this paper examines the world's largest heavy-freight railway – the Daqin Railway – to study the impacts of the seasonally frozen soil layer on vibrational acceleration. With increasing axle weight, the peak and mean values of the acceleration increased. Vibration acceleration attenuated the most from the shoulder to the embankment footing (51%–71%), while the vibrations at 70 m were attenuated by more than 90%. Certain measures must be taken by those living within 70 m of the railway shoulder. In addition, the acceleration peak caused by trains running in parallel after meeting amplified the vibration by 10%–39%. Moreover, the overall vibrations attenuate with increasing distance, whereas the local vibrations fluctuate. During the freezing period, the acceleration is 13%–26% greater than that of the unfrozen period. The vibration acceleration spectrum is comparatively wider, and is dominated by high-frequency components. Finally, using a three-dimensional model verified by field measurements, the vibrational features were analyzed at different embankment and foundation depths.

Theoretical Road Damage Due to Dynamic Tyre Forces of Heavy Vehicles Part 1: Dynamic Analysis of Vehicles and Road Surfaces

1988 ◽  
Vol 202 (2) ◽  
pp. 103-108 ◽  
Author(s):  
D Cebon
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Full Scale ◽  
Heavy Vehicles ◽  
Road Vehicles ◽  
Vehicle Simulation ◽  
The Road ◽  
Road Surfaces ◽  
Full Scale Tests

Theory is presented for simulating the dynamic wheel forces generated by heavy road vehicles and the resulting dynamic response of road surfaces to these loads. Sample calculations are provided and the vehicle simulation is validated with data from full-scale tests. The methods are used in the accompanying paper to simulate the road damage done by a tandem-axle vehicle.

scholarly journals RIGID BODY MOTION OF A FLOATING BREAKWATER

1984 ◽  
Vol 1 (19) ◽  
pp. 179
Author(s):  
Robert W. Miller ◽  
Derald R. Christensen
Keyword(s):  
Dynamic Response ◽  
Rigid Body ◽  
Frequency Domain ◽  
Field Measurements ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Full Scale ◽  
Body Motion ◽  
Floating Breakwater ◽  
Scale Field

Predictions of the dynamic response of a floating breakwater obtained from a frequency domain analysis are compared with full-scale field measurements. Those parameters prominently affecting accurate response predictions are identified and discussed.

Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

2018 ◽  
Vol 84 (10) ◽  
pp. 23-28
Author(s):  
D. A. Golentsov ◽  
A. G. Gulin ◽  
Vladimir A. Likhter ◽  
K. E. Ulybyshev
Keyword(s):  
Experimental Data ◽  
Early Stage ◽  
Experimental Studies ◽  
Material Model ◽  
Total Charge ◽  
Cross Sectional ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Order Of Magnitude ◽  
Using Data

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

Saturated Hydraulic Conductivity of Clayey Tills and the Role of Fractures

1990 ◽  
Vol 21 (2) ◽  
pp. 119-132 ◽  
Author(s):  
Johnny Fredericia
Keyword(s):  
Hydraulic Conductivity ◽  
American Studies ◽  
Field Measurements ◽  
Present Knowledge ◽  
Saturated Hydraulic Conductivity ◽  
Field Observations ◽  
Laboratory Measurements ◽  
Vertical Hydraulic Conductivity ◽  
Data Field

The background for the present knowledge about hydraulic conductivity of clayey till in Denmark is summarized. The data show a difference of 1-2 orders of magnitude in the vertical hydraulic conductivity between values from laboratory measurements and field measurements. This difference is discussed and based on new data, field observations and comparison with North American studies, it is concluded to be primarily due to fractures in the till.

Investigation of planing craft maneuverability using full-scale tests

2021 ◽  
pp. 147509022110303
Author(s):  
Kazem Sadati ◽  
Hamid Zeraatgar ◽  
Aliasghar Moghaddas
Keyword(s):  
Full Scale ◽  
Performance Characteristics ◽  
Forward Speed ◽  
Speed Reduction ◽  
Planing Craft ◽  
Full Scale Tests ◽  
Turning Maneuver

Maneuverability of planing craft is a complicated hydrodynamic subject that needs more studies to comprehend its characteristics. Planing craft drivers follow a common practice for maneuver of the craft that is fundamentally different from ship’s standards. In situ full-scale tests are normally necessary to understand the maneuverability characteristics of planing craft. In this paper, a study has been conducted to illustrate maneuverability characteristics of planing craft by full-scale tests. Accelerating and turning maneuver tests are conducted on two cases at different forward speeds and rudder angles. In each test, dynamic trim, trajectory, speed, roll of the craft are recorded. The tests are performed in planing mode, semi-planing mode, and transition between planing mode to semi-planing mode to study the effects of the craft forward speed and consequently running attitude on the maneuverability. Analysis of the data reveals that the Steady Turning Diameter (STD) of the planing craft may be as large as 40 L, while it rarely goes beyond 5 L for ships. Results also show that a turning maneuver starting at planing mode might end in semi-planing mode. This transition can remarkably improve the performance characteristics of the planing craft’s maneuverability. Therefore, an alternative practice is proposed instead of the classic turning maneuver. In this practice, the craft traveling in the planing mode is transitioned to the semi-planing mode by forward speed reduction first, and then the turning maneuver is executed.

scholarly journals Hydraulic transmissivity inferred from ice-sheet relaxation following Greenland supraglacial lake drainages

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ching-Yao Lai ◽  
Laura A. Stevens ◽  
Danielle L. Chase ◽  
Timothy T. Creyts ◽  
Mark D. Behn ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Ice Sheet ◽  
Drainage System ◽  
Greenland Ice Sheet ◽  
Field Observations ◽  
Surface Uplift ◽  
Drainage Networks ◽  
Order Of Magnitude ◽  
Lake Drainage ◽  
Magnitude Increase

AbstractSurface meltwater reaching the base of the Greenland Ice Sheet transits through drainage networks, modulating the flow of the ice sheet. Dye and gas-tracing studies conducted in the western margin sector of the ice sheet have directly observed drainage efficiency to evolve seasonally along the drainage pathway. However, the local evolution of drainage systems further inland, where ice thicknesses exceed 1000 m, remains largely unknown. Here, we infer drainage system transmissivity based on surface uplift relaxation following rapid lake drainage events. Combining field observations of five lake drainage events with a mathematical model and laboratory experiments, we show that the surface uplift decreases exponentially with time, as the water in the blister formed beneath the drained lake permeates through the subglacial drainage system. This deflation obeys a universal relaxation law with a timescale that reveals hydraulic transmissivity and indicates a two-order-of-magnitude increase in subglacial transmissivity (from 0.8 ± 0.3 $${\rm{m}}{{\rm{m}}}^{3}$$ m m 3 to 215 ± 90.2 $${\rm{m}}{{\rm{m}}}^{3}$$ m m 3 ) as the melt season progresses, suggesting significant changes in basal hydrology beneath the lakes driven by seasonal meltwater input.

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