Full-scale Field Study Research Articles

Effect of Installation Method on the Uplift Capacity of Single Driven Steel Piles: Full-Scale Field Study

Effect of Installation Method on the Uplift Capacity of Single Driven Steel Piles: Full-Scale Field Study

EFFICIENCY OF USING PORTABLE FIRE EXTINGUISHERS WHEN EXTINGUISHING LITHIUM-ION BATTERIES

The article substantiates the trends in using electric energy storage systems consisting of a battery, an inverter, connecting conductors, safety automation, and, if necessary, solar panels. Such systems typically use lithium-ion batteries because of several technical advantages: high specific energy capacity, high discharge-charging currents, and many charge-discharge cycles, i.e., longevity. The chemical and electrochemical reactions that occur during the charge-discharge cycles of lithium-ion batteries can lead to irreversible electrothermal processes. Such processes cause an uncontrolled increase in temperature, the release of hazardous gases, fires, and explosions, often accompanied by fire. Therefore, the authors conducted a successful full-scale field study of the effect of various extinguishing agents of the most common portable fire extinguishers in Ukraine on the efficiency of extinguishing lithium-ion batteries. Based on the experiment, we found that extinguishing the lithium-ion module using a portable carbon dioxide fire extinguisher is the least effective among the extinguishers studied, with the resumption of flame combustion occurring within 3–4 s after the cessation of carbon dioxide supply to the combustion centre. When using a portable powder fire extinguisher, the flame combustion of the test module resumed after 18–20 s. The desired extinguishing effect was achieved using low-density air-mechanical foam from the VVK-5 fire extinguisher and sprayed water with salt additives from a water extinguisher. Based on the obtained research results, we proposed recommendations for the selection of standards for the availability and use of portable fire extinguishers for the effective extinguishing of lithium-ion batteries at the rate of at least 5 kg of charge of working solution or water with salt additives per 5 kWh of energy capacity of a lithium-ion battery. Further research will identify influence patterns of the intensity of extinguishing agent supply on the efficiency of extinguishing lithium-ion batteries. Keywords: lithium-ion battery, fire, irreversible electrothermal process, fire safety.

Full-Scale Field Study of Instrumented Under-Reamed Piles in Clay

Full-Scale Field Study of Instrumented Under-Reamed Piles in Clay

Construction of Geosynthetic–Reinforced Pavements and Evaluation of Their Impacts

Geosynthetic materials (i.e., geogrids, geotextiles and other geocomposites) act as an interlayer system and are widely used in construction applications. In pavement structures, geosynthetic layers provide potential benefits such as reinforcement, reflective cracking mitigation, increased fatigue life, and improved drainage and filtering. However, few studies have addressed the installation and construction practices of geosynthetics in pavements. Furthermore, the study of geosynthetics and their contribution during construction are limited. In this paper, a full-scale field study was conducted and three trial sections were constructed; two types of geosynthetics, a fibreglass geogrid and a geogrid composite, were installed in the asphalt binder course and at the interface between the subgrade and base layer, respectively, to be compared with a control section without geosynthetic reinforcement. Trial sections were instrumented to monitor the pressure applied on the subgrade, the strain in the base lift of the asphalt binder course, the temperature, and the moisture within the pavement structure during construction. In addition, post-construction field testing was performed to measure the stiffness of the pavements after construction. The results indicated that geosynthetic-reinforced pavements can maintain pavement resilience during construction and significantly mitigate the disturbances caused by construction activities. The geogrid embedded in the asphalt layer was demonstrated to reduce the pressure at the subgrade caused by paving equipment by 70% compared with the control section, while simultaneously reducing the longitudinal and transverse strain at the bottom of the asphalt layer by 54% and 99%. Observations from the geogrid composite test section also demonstrate the potential to minimize the impacts of future freeze–thaw at the subgrade due to the improved drainage and indirect insulation effect.

Load-Settlement Characteristics of Stone Column Reinforced Soft Marine Clay Deposit: Combined Field and Numerical Studies

Foundations supporting infrastructure built on soft and compressible marine soil are unlikely to sustain due to possibility of undrained shear failure or excessive settlement of the supporting soil. This necessitates the importance of implementing an adequate ground improvement strategy. Among different techniques, soft soil reinforcing by the installation of stone columns is one of the most successful methods in terms of long-term stability of foundations. To investigate the load-settlement characteristics of such reinforced soil, a group of closely spaced stone columns was constructed at a location along the eastern coast of Australia. The site geology revealed thick layers of soft, compressible marine clay deposit. These stone columns were loaded by constructing earthen embankment and the resulting load-settlement characteristics were measured by an array of sensors. A two-dimensional plane strain analysis was performed using finite element modeling simulations. Comparison of numerical results with the field data demonstrated accuracy of the numerical model. Additional studies were carried out to investigate the efficiency of the model. This paper integrates the new findings from the full-scale field study and advanced numerical simulations while drawing pertinent conclusions.

Closure to “Full-Scale Field Studies to Evaluate Deep Soil Mixing in Stabilizing Expansive Soils”

Closure to “Full-Scale Field Studies to Evaluate Deep Soil Mixing in Stabilizing Expansive Soils”

Discussion of “Full-Scale Field Studies to Evaluate Deep Soil Mixing in Stabilizing Expansive Soils”

Discussion of “Full-Scale Field Studies to Evaluate Deep Soil Mixing in Stabilizing Expansive Soils”

Illumination and Lighting Energy Use in an Office Room with a Horizontal Light Pipe: Field Study at a High Latitude

This paper describes a field study of the illumination and lighting energy use in a full-scale test office in a building located in southern Norway. Natural light is provided to the office via southwest-oriented windows and a horizontal light pipe (HLP) with a daylight entrance facing the south. The study is a full-scale field study, and it is a continuation of the recently published study addressing a scale model and a theoretical model. The novelty of this study is a custom-made reflector for the HLP’s daylight distribution to preserve the features of natural light noted as the primary human association with daylight. The main research aim was to determine if the daylighting level in the back of the office was improved as a consequence of the daylighting provision from the HLP compared to a reference situation without a HLP, as well as whether the lighting energy use for the electric lighting system that was supposed to provide the recommended light level was reduced. This study includes monitoring of the outdoor and indoor illuminance levels as well as the energy consumption of the luminaires throughout the study’s test period and a corresponding reference period. The recorded data were used to test hypothesis applying inferential statistical analyses. In conclusion, this paper reports an increased daylight level on the working area in the rear part of the office of approximately 200 to 300 lx during clear and sunny days at equinox. The increased daylight level on the working area near the window of approximately 50 lx was also recorded. These findings have important implications for energy balance in the Zero Energy Buildings (ZEB) and the ‘peak load’ for energy consumption.

Influence of asphalt thickness on performance of geosynthetic-reinforced asphalt: Full-scale field study

In this study, a series of controlled traffic loadings was conducted on unreinforced and geosynthetic-reinforced full-scale asphalt overlays. Unlike the common objective of using paving interlayers to mitigate the development of reflective cracks, the main purpose of adopting geosynthetics for this study was to render an increased roadway structural capacity. The project involved instrumented test sections constructed during the rehabilitation of an in-service roadway in Texas, USA. The rehabilitation involved repairing the pre-existing pavement, placing tack coat, installing a geosynthetic interlayer (except in the unreinforced section), and finally constructing a 75 mm-thick asphalt overlay. This overlay comprised a 50 mm-thick, dense-graded (TY-D) layer overlain by a 25 mm-thick, thin-overlay mixture (TOM) layer. Controlled traffic loadings were conducted, which involved driving standard and light axle loads directly above asphalt strain gauges that had been installed at mid-depth of the pre-existing asphalt layer. Comparison of tensile strains among the different test sections revealed significantly smaller tensile strains in the geosynthetic-reinforced sections compared to those obtained in the unreinforced section. Consequently, and even though geosynthetic interlayers have often been adopted to minimize reflective cracking in asphalt overlays, the field monitoring results generated in this study demonstrate that they also provide added roadway structural capacity.

Asserting the Applicability of Copper Slag and Fly Ash as Cemented Base Materials in Flexible Pavement from a Full-Scale Field Study

This research made innovative use of copper slag and fly ash in the construction of a cemented base course of flexible pavement. A full-scale field study evaluated the structural and functional performance of flexible pavement test sections constructed using various combinations of copper slag and fly ash (Class F or Class C) with and without lime. Various performance parameters, namely deflection basin parameters, dissipated energy, back-calculated elastic modulus, service life ratio, and roughness index, were evaluated for flexible pavement test sections constructed with 250-mm-thick conventional granular base [wet-mix macadam (WMM)], 150-mm- and 250-mm-thick copper slag–Class F fly ash–lime (CFL) (70% copper slag +23% Class F fly ash +7% lime) and copper slag–Class C fly ash (CCF) (40% copper slag +60% Class C fly ash) base layers. Falling weight deflectometer tests and bump integrator tests were performed in situ; laboratory tests, namely unconfined compression and resilient modulus tests, were performed on core samples. The average elastic moduli, back-calculated from six FWD tests conducted over 15 months after construction, for CCF and CFL base were 430 and 602 MPa, which are more than 3 times that of WMM. Significant waste utilization up to 1,348 tons of copper slag and 945 tons of fly ash per kilometer length of road can be achieved by using CCF and CFL mixes in base layers of flexible pavement with a service life ratio as high as 1.78 and cost efficiency of 17.4%.

Novel hybrid modeling approach for utilizing simple linear regression models to solve multi-input nonlinear problems of indoor humidity modeling

Investigating indoor humidity is important because abnormal moisture levels can damage building structures and result in poor indoor air quality. Outdoor humidity, ventilation rate, and internal moisture load are the three dominant factors affecting indoor humidity. State-of-the-art methods, particularly full-scale field studies for determining these three factors and indoor humidity can be both time consuming and labor intensive. This study proposes a radically new methodology to effectively model the influence of these three factors on indoor humidity for a mechanically ventilated building/space. The methodology starts with a simple linear regression (SLR) constructed by measuring indoor and outdoor humidity and then hybrids a novel analytical approach that accurately predicts the impact of ventilation rate and internal moisture load on indoor humidity. The proposed upgraded SLR model was successfully validated with high accuracy by both experiments and numerical simulations using TRNSYS commercial software. The results demonstrate the ability of the developed SLR to accurately model indoor humidity and account for the moisture exchange between indoor air and building structures/furnishings. Inferring these relationships and their influences on indoor humidity presents a challenging task. The developed model is generic and unique and supports fast and inexpensive field studies by ensuring that the measurements of indoor and outdoor humidity are sufficient to derive field tests of the impacts of outdoor humidity, ventilation rate, and internal moisture loads on indoor humidity. The proposed model can be further developed as a standardized moisture assessment tool for benchmarking building performance.

Full-Scale Field Studies to Evaluate Deep Soil Mixing in Stabilizing Expansive Soils

An evaluation of deep soil mixing (DSM) technology in stabilizing expansive soils was conducted by designing and constructing two full-scale test sections. The test sections were instrumented and installed with different numbers of DSM columns and area ratios. Their performance was evaluated by comparing the test sections with two untreated test sections. The performance of the DSM test sections was measured by addressing the shrink and swell behaviors using vertical and lateral soil movements and the swell pressures within the treated soil mass. This paper discusses the construction of the test sections, the instrumentation details, and comprehensive analyses of the field monitored data. The untreated test sections experienced absolute vertical soil movements on the order of 35 mm or greater, whereas the treated test sections had movements in the range of 10 to 25 mm. Similar observations were recorded for the lateral soil movements and swell pressure changes in both the untreated and treated sections. Unlike the DSM-treated test sections, the untreated test sections showed repeated soil movements with field moisture content changes due to periodic dry/wet climatic conditions. Results from nondestructive testing (NDT) revealed that the overall stiffness of the DSM-treated test sections was superior to that of the untreated sections. This study showed that DSM technology is a viable option for stabilizing expansive soil formations with moderate to deeper active depths.

Experimental field study of floater motion effects on a main bearing in a full-scale spar floating wind turbine

In this paper we present a full-scale experimental field study of the effects of floater motion on a main bearing in a 6 MW turbine on a spar-type floating substructure. Floating wind turbines are necessary to access the full offshore wind power potential, but the characteristics of their operation leave a gap with respect to the rapidly developing empirical knowledge on operation of bottom-fixed turbines. Larger wind turbines are one of the most important contributions to reducing cost of energy, but challenge established drivetrain layouts, component size envelopes and analysis methods. We have used fibre optic strain sensor arrays to measure circumferential strain in the stationary ring in a main bearing. Strain data have been analysed in the time domain and the frequency domain and compared with data on environmental loads, floating turbine motion and turbine operation. The results show that the contribution to fluctuating strain from in-plane bending strain is two orders of magnitude larger than that from membrane strain. The fluctuating in-plane bending strain is the result of cyclic differences between blade bending moments, both in and out of the rotor plane, and is driven by wind loads and turbine rotation. The fluctuating membrane strain appears to be the result of both axial load from thrust, because of the bearing and roller geometry, and radial loads on the rotating bearing ring from total out-of-plane bending moments in the three blades. The membrane strain shows a contribution from slow-varying wind forces and floating turbine pitch motion. However, as the total fluctuating strain is dominated by the intrinsic effects of blade bending moments in these turbines, the relative effect of floater motion is very small. Mostly relevant for the intrinsic membrane strain, sum and difference frequencies appear in the measured responses as the result of nonlinear system behaviour. This is an important result with respect to turbine modelling and simulation, where global structural analyses and local drivetrain analyses are frequently decoupled.

A full-scale field study on mitigation of environmental ground vibrations by using open trenches

Environmental ground vibrations induced by construction operations, machine foundations, vehicular and railway traffic may cause discomfort to the dwellers in their immediate vicinity and malfunctioning of sensitive equipment in nearby structures. Associated with technological development and rapid industrialization, undesired vibrations around the residential areas have increased. Hence, the isolation of those vibrations has become an important issue. Open trenches are mainly employed as wave barriers in mitigation of undesired vibrations. Recent studies have focused on the parameters affecting the vibration isolation performance of open and in-filled trenches. It is stated that screening effectiveness mainly depends on the type of the vibration source and geometric dimensions of open trenches along with the local site conditions. In the present study, a series of full-scale field experiments were conducted to identify the effects of governing parameters on efficiency. The amplitudes of ground vibrations, artificially generated on the site, were measured through highly sensitive accelerometers at different test configurations. It was concluded that the frequency of vibrations had more influence than the actual depth of the barrier on screening effectiveness. Better isolation can be achieved in a region close to the trench while the effectiveness decreases at great distances. In addition, the results were compared with those of recently reported in experimental studies.

Full-scale field study of using geofoam to reduce earth pressures on buried concrete culverts

Applications of geofoam for buried culverts/pipes keep increasing; however, the design of such applications is still challenging due to lack of full-scale studies. Considering practice needs, a full-scale field study was carried out to investigate the effectiveness of different geofoams with different layouts to reduce overburden stresses on deeply buried, large-size culverts. Among the eight test sections, five were installed with two different of geofoams (7.5 and 15 kg/m3) in thicknesses of 300 and 600 mm and the remaining three were built with loose sand, lightly and normally compacted clay, respectively. The acquired data indicated that the geofoam can greatly reduce the overburden stress over the culvert. In general, higher compressibility of geofoam resulted in greater stress transfer but did not cause excessive settlement at the surface due to significant burial depth. However, due to its large span and dome shape, a secondary soil arching formed when the soil over shoulder settled more than that over the crown, which readjusted the stress and resulted in further reduction in the stress at the culvert shoulder but partially compromised the stress reduction at the crown. Such phenomenon shall be appropriately addressed to avoid unexpected damage to buried culverts or pipes.

Evaluating the Performance of Wicking Geotextile in Providing Drainage for Flexible Pavements Built over Expansive Soils

The longevity and performance of a pavement section depend on the characteristics of the subgrade soil. A majority of the pavements in North Texas, U.S., are constructed on expansive soils. The deterioration of the pavement performance because of rutting, cracking, and differential heaving is a regular phenomenon in the regions predominantly distributed with expansive soils. The pavements, particularly those built for low-volume traffic conditions, experience distress because of the high swelling and shrinkage characteristics of the underlying problematic soils. Geosynthetics have been traditionally used to improve such poor subgrades because of their many benefits, such as ease of installation, and ample mechanical and hydraulic properties. In the last decade, a newly available wicking geotextile, with a moisture redistribution capacity, has been developed to improve the performance of pavements constructed over expansive and frozen soils. In this study, small-scale laboratory and full-scale field studies were conducted to comprehend the wicking ability of this innovative geotextile in an expansive soil environment. Full-scale test sections were constructed with reclaimed asphalt pavement aggregate and traditional crushed stone aggregates in the base layer near North Texas. Details of the construction and instrumentation procedure are discussed in this paper. A comparative study between the performance of the pavement sections subjected to traffic loads and moisture intrusion was also performed. Furthermore, the rutting life of the sections, estimated using a linear elastic model, was compared and validated using the in situ data. The observations during the initial phase indicated that the wicking geotextile has the potential to improve the long-term pavement performance.

Performance of Driven Grouted Micropiles: Full-Scale Field Study

Abstract A new installation method for micropile is introduced, called driven grouted micropiles (DGMs), in which closed-end perforated steel pipes are driven to the refusal depth using a light ham...

A full-scale field study for evaluation of simple analytical models of cross ventilation and single-sided ventilation

In this study, we evaluated several simple natural ventilation models of cross ventilation and single-sided ventilation with data measured in a full-scale field study in London. In the field study, the ventilation rate in a naturally ventilated office was measured using a tracer gas technique with CO2. Internal temperatures were measured using a vertical temperature array. The external temperature, wind speed and direction were measured at a nearby weather station. In addition, a 1:200 scale model of the urban area within 300 m of the test room was built in a wind tunnel to measure the pressure coefficients. The ventilation models were evaluated with input data from two sources. Wind data from a nearby airport and pressure coefficients from the literature were used, as is common practice. Alternatively, wind data measured at the local weather station and the pressure coefficients measured from wind tunnel experiments were used. The results showed that, regardless of the input data sources, the cross-ventilation model in general gives reasonable predictions. For single-sided ventilation, several empirical models were evaluated and poor predictions were obtained using the models. We discuss ways in which models of natural ventilation might be improved in the future.

Recycled aggregate concrete from large-scale production to sustainable field application

Concrete waste is the most prominent construction and demolition waste generated by the construction industry, which is mainly disposed to landfills. Recycling this waste in the form of recycled concrete aggregates (RCA) and substituting it for natural aggregates in the production of concrete could lead to environmental conservation. A growing body of literature in lab settings has already recognized the importance of utilizing RCA in the production of new concrete. However, intense utilization of RCA in the large-scale industrial production of new concrete (structural and non-structural) is not widely accepted by international standards due to its high porosity, a disparity of source concrete and lack of territorial field studies. In this paper, two full-scale field studies of the foundation system and municipal sidewalk constructed with recycled aggregate concrete (RAC) are presented. In addition to this, the long-term performance of RAC examined for 5 years in terms of in-place compressive strength is reported. Moreover, strength correlations developed specifically for RAC for the estimation of compressive strength based on rebound numbers are discussed. This study shows that RCA has significant potential of using as substitution of natural aggregate in the production of concrete of 25 and 32 MPa compressive strength. Furthermore, RAC shows a higher rate of compressive strength development after 28 days of curing and results in comparable long-term compressive strength to conventional concrete. By providing an insight into the sustainable application of RCA in the production of new concrete, the results of this study can serve as a basis for updating the current standards in Canada.

Performance evaluation of geosynthetic reinforced flexible pavement: a review of full-scale field studies

Many experimental studies have shown that geosynthetic reinforcement of flexible pavement can be beneficial in terms of extending their service life and decreasing the required structural number of the pavement. Although numerous researches have performed experimental and numerical studies to evaluate the benefits of these reinforcements, comprehensive comparisons are lacking among the different investigations. This paper reviews typical field experimental studies on geosynthetic reinforcement of flexible pavement performed by various investigators. Researchers have found that the main appreciable improvement of geosynthetics reinforcement depends on various factors such as subgrade stiffness, base aggregate thickness and quality, hot mix asphalt thickness and quality, geogrid stiffness/location and so on. The granular equivalent (G.E.) factor was determined based on the results of the falling weight deflectometer (FWD) and the results of the unreinforced and reinforced section were compared to obtain the G.E. factors based on mentioned factors of reinforcements. Then, a unique formula is presented in this study, according to the performed comparison of the results. Although more investigations are needed to develop the presented method and general corrections, the results of this study can be used by the designers to evaluate the geosynthetic reinforcement of flexible pavements in their designs as well.