Alternate Method of Pavement Assessment Using Geophones and Accelerometers for Measuring the Pavement Response

Pavement instrumentation with embeddable in-situ sensors has been a feasible approach to determine pavement deteriorations. Determining pavement deflections during the passage of the load is a promising strategy to determine the overall performance of the pavement. There are different devices that apply loads to the pavements and measure the deflection basin, these include static, vibratory, or impulse loadings. Most commonly used are the static loading like Benkelman beam and impulse loading like the Falling Weight Deflectometer (FWD). However, these techniques are costly and the measurements are recorded infrequently, i.e., once per year or two years. This study focuses on the use of geophones and accelerometers to measure the surface deflections under traffic loading. To develop a method to measure pavement deflections, the sensors were submitted first to laboratory tests, and then tested in situ, in a full scale accelerated pavement test. In the laboratory, the sensors were submitted to different types of loading using a vibrating table. These tests were used to determine the noise and sensitivity of the sensors, and then to evaluate their response to signals simulating pavement deflections under heavy vehicles. The sensor response was compared with measurements of a reference displacement sensor. Different processing techniques were proposed to correct the measurements from geophones and accelerometers, in order to obtain reliable deflection values. Then, the sensors were evaluated in a full scale accelerated test, under real heavy axle loads. Tests were performed at different loads and speeds, and the deflection measurements were compared with a reference anchored deflection sensor. The main advantage of using accelerometers or geophones embedded in the pavement is to enable continuous pavement monitoring, under real traffic. The sensor measurements could also be used to determine the type of vehicles and their corresponding speeds. The study describes in detail the signal analysis needed to measure the pavement deflections accurately. The measurements of pavement deflection can be then used to analyze the pavement behavior in the field, and its evolution with time, and to back-calculate pavement layer properties.

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Field Study of In Situ Subgrade Soil Response Under Flexible Pavements

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1639-03 ◽

1998 ◽

Vol 1639 (1) ◽

pp. 23-35 ◽

Cited By ~ 2

Author(s):

Shongtao Dai ◽

Dave Van Deusen

Keyword(s):

Resilient Modulus ◽

Soil Pressure ◽

Vertical Pressure ◽

Soil Response ◽

Subgrade Soils ◽

Linear Elastic ◽

Subgrade Soil ◽

In Situ Sensors ◽

Falling Weight

Falling weight deflectometer (FWD) and truck tests were performed on three instrumented flexible pavement sections at the Minnesota Road Research project. The purposes of the study were (1) to investigate sub-grade soil response under FWD and moving truck loads and (2) to estimate in situ resilient modulus of the subgrade soil. The truck tests were performed at various speeds ranging from 16 to 78 km/h. The subgrade deformations and the vertical pressures on the top of the subgrade soils were measured from in situ displacement and soil pressure gauges. The experimental results showed that the deformations and the vertical pressures, in general, did not show significant dependency of truck speed within the above speed range. However, a slight decrease of the vertical pressure with increase of speed was observed for a thin conventional pavement section, while the vertical pressure in a relatively thick pavement section appeared to be less sensitive to speed. The results from FWD tests indicated that the subgrade deformation was linearly related to the FWD loads up to approximately 40 kN. Furthermore, a method is presented to estimate in situ subgrade modulus using the linear elastic theory and the measurements from the in situ sensors. The estimated modulus is comparable with the laboratory results at a low deviator stress level and is lower than modulus obtained from the backcalculation using FWD deflection basins.

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Upscaling THM modeling from small-scale to full-scale in-situ experiments in the Callovo-Oxfordian claystone

International Journal of Rock Mechanics and Mining Sciences ◽

10.1016/j.ijrmms.2020.104582 ◽

2021 ◽

Vol 144 ◽

pp. 104582

Author(s):

D.M. Seyedi ◽

C. Plúa ◽

M. Vitel ◽

G. Armand ◽

J. Rutqvist ◽

...

Keyword(s):

Full Scale ◽

Small Scale ◽

In Situ Experiments

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Investigation of planing craft maneuverability using full-scale tests

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/14750902211030386 ◽

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.

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In situ sensors for blood-brain barrier (BBB) on a chip

Sensors and Actuators Reports ◽

10.1016/j.snr.2021.100031 ◽

2021 ◽

Vol 3 ◽

pp. 100031

Author(s):

Yan Liang ◽

Jeong-Yeol Yoon

Keyword(s):

Blood Brain Barrier ◽

Brain Barrier ◽

Blood Brain ◽

In Situ Sensors

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In situ measurement of flyheight variations in magnetic storage devices through the use of sample margin signal processing techniques

IEEE Transactions on Magnetics ◽

10.1109/20.104753 ◽

1990 ◽

Vol 26 (5) ◽

pp. 2427-2429

Author(s):

G.J. Kerwin

Keyword(s):

Signal Processing ◽

In Situ Measurement ◽

Magnetic Storage ◽

Storage Devices ◽

Processing Techniques ◽

Magnetic Storage Devices ◽

Signal Processing Techniques

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Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

MRS Proceedings ◽

10.1557/proc-663-561 ◽

2000 ◽

Vol 663 ◽

Cited By ~ 2

Author(s):

J. Samper ◽

R. Juncosa ◽

V. Navarro ◽

J. Delgado ◽

L. Montenegro ◽

...

Keyword(s):

Large Scale ◽

Reference Model ◽

Numerical Models ◽

Full Scale ◽

Small Scale ◽

Model Parameters ◽

In Situ Test ◽

Wide Range ◽

Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

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The role of forest deadwood in rockfall protection

10.5194/egusphere-egu21-10791 ◽

2021 ◽

Author(s):

Adrian Ringenbach ◽

Peter Bebi ◽

Perry Bartelt ◽

Andrin Caviezel

Keyword(s):

Basal Area ◽

Spruce Forest ◽

Runout Distance ◽

In Situ Sensors ◽

Efficient Protection ◽

Cost Efficient ◽

Study Sites ◽

Rockfall Protection

<p>Forests with a high density and basal area of living trees are known for their function as natural and cost-efficient protection against rockfall. The role of deadwood, however, is less understood. We address this knowledge gap in this contribution as we present the results of repeated real-scale experiments in a) a montane beech-spruce forest with and without deadwood and b) in a subalpine scrub mountain pine-spruce forest with deadwood. We used artificial rocks with either an equant or platy shape, masses between 45 kg and 800 kg (&#8776; 0.3 m3), and equipped with in-situ sensors to gain insights into rotational velocities and impact-accelerations. Clusters of deadwood and erected root plates reduced the mean runout distance at both study sites. For site a), we found that more rocks were stopped behind lying than living trees and that the stopping effect of deadwood was greater for equant compared to platy rock shapes. Site b) revealed a braking effect of scrub mountain pines for relatively small (45 kg), but also a visible reduction in rotational velocities for the 800 kg rocks sensor stream. We conclude that deadwood must be taken into account in rockfall modeling and the management of rockfall protection forests.</p>

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Distributed Modal Voltages of Nonlinear Paraboloidal Shells With Distributed Neurons

Journal of Vibration and Acoustics ◽

10.1115/1.1640359 ◽

2004 ◽

Vol 126 (1) ◽

pp. 47-53 ◽

Cited By ~ 11

Author(s):

H. S. Tzou ◽

J. H. Ding

Keyword(s):

Dynamic Responses ◽

Dynamic State ◽

Structural Components ◽

Shells Of Revolution ◽

Membrane Component ◽

Fully Integrated ◽

In Situ Sensors ◽

Membrane Components ◽

Paraboloidal Shell

Effective health monitoring and distributed control of advanced structures depends on accurate measurements of dynamic responses of elastic structures. Conventional sensors used for structural measurement are usually add-on “discrete” devices. Lightweight distributed thin-film piezoelectric neurons fully integrated (laminated or embedded) with structural components can serve as in-situ sensors monitoring structure’s dynamic state and health status. This study is to investigate modal voltages and detailed signal contributions of linear or nonlinear paraboloidal shells of revolution laminated with piezoelectric neurons. Signal generation of distributed neuron sensors laminated on paraboloidal shells is defined first, based on the open-voltage assumption and Maxwell’s principle. The neuron signal of a linear paraboloidal shell is composed of a linear membrane component and a linear bending component; the signal of a nonlinear paraboloidal shell is composed of nonlinear and linear membrane components and a linear bending component due to the von Karman geometric nonlinearity. Signal components and distributed modal voltages of linear and nonlinear paraboloidal shells with various curvatures and thickness are investigated.

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