scholarly journals The displacement of structures founded on expansive soils – unapparent causes

2018 ◽  
Vol 45 ◽  
pp. 00098
Author(s):  
Szymon Topoliński ◽  
Aleksandra Gorączko ◽  
Jacek Sztubecki ◽  
Adam Bujarkiewicz
Keyword(s):  
Environmental Changes ◽  
Expansive Soils ◽  
Monitoring Program ◽  
Field Measurements ◽  
Building Structure ◽  
Volume Changes ◽  
Coordinate Method ◽  
Geotechnical Investigations ◽  
Vertical Displacements ◽  
Soil And Water

Determining the causes for the displacement of damaged structures located on expansive soils often requires meticulous and individual analyses of many factors. The sensitivity of the expansive subsoils to environmental changes in humidity, activating its volume changes, requires a careful and comprehensive monitoring of structures susceptible to deformation. The article presents the method of the diagnostics of structures, located on an expansive subsoil in Poland. The methodology and preliminary results of the measurement of the vertical displacements of a building structure founded on expansive subsoil were presented. During field measurements, periodic geodetic measurements of structural displacements were carried out using classical precision levelling and the coordinate method of the Leica TDRA 6000 laser station. At the same time, geotechnical investigations were carried out describing the condition of the ground on which the structure is located. An analysis of the obtained results allowed determining the existing soil and water conditions and drawing unapparent conclusions regarding the causes of damage to the tested structure. On this basis, a further structures monitoring program was established.

scholarly journals Displacements of Object Founded on Expansive Soils—A Case Study of Light Construction

Geosciences ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 153
Author(s):  
Aleksandra Gorączko ◽  
Jacek Sztubecki ◽  
Adam Bujarkiewicz ◽  
Szymon Topoliński
Keyword(s):  
Environmental Changes ◽  
Expansive Soils ◽  
Seasonal Fluctuations ◽  
Volume Changes ◽  
Expansive Clays ◽  
Natural Moisture Content ◽  
Geotechnical Investigations ◽  
Main Factors ◽  
Spatial Displacements

The paper presents results of observations of a light structure damaged by irregular vertical and horizontal deformations on Neogene expansive clays, typical for area in Central Poland. The sensitivity to environmental changes of humidity in such subsoils can activate volume changes, which causes the destruction of many objects susceptible to deformation. Detailed geotechnical investigations, including seasonal fluctuations of natural moisture content, were carried out for over a year, describing the dynamism of conditions of clays in the foundation zone. Parallel geodetic measurements of vertical and horizontal displacements were carried out, using classical precision leveling and the coordinate method of the Leica TDRA 6000 laser station. The network of measurement points has been specially designed and implemented to follow the spatial displacements of the structure. The network points were placed at the bottom of pillars and on the flooring of the structure located in the upper part. In the paper, the results of the vertical and horizontal periodical measurement of displacements of an investigated construction over the year were discussed to identify the main factors influencing the mechanism of damage of the observed structure.

scholarly journals Development of Airtightness of Estonian Wooden Buildings

2019 ◽  
Vol 24 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Jaanus Hallik ◽  
Targo Kalamees
Keyword(s):  
Field Measurements ◽  
Building Structure ◽  
Air Leakage ◽  
Large Dataset ◽  
Apartment Buildings ◽  
Timber Construction ◽  
Significant Difference ◽  
Minimum Requirements ◽  
Post Hoc

The field measurements of airtightness in Estonian detached and apartment buildings conducted between2003 – 2017 were combined into a large dataset for further analysis. The buildings were classified basedon building structure, number of storeys, year of construction, energy classification and compactnessfactors. A subset with all wooden buildings (313 in total) was statistically analysed to determine theaverage (median) air leakage rates at 50 Pa and tested (Kruskal-Wallis test with post-hoc Conovertest) for significant differences within the grouping factors. As expected, the median air leakage (q50)of older buildings between 10.7 and 13.9 m3/(hm2) has decreased to 1.1 m3/(hm2) after the minimumrequirements for energy efficiency have taken effect. A more detailed analysis on newer buildings showedthat quality of the workmanship combining systematic measurement routines as well as prefabrication,yields significantly lower median air leakages compared to on-site construction. The buildings with betterenergy classification targets also achieved lower median air leakages compared to buildings designedto meet minimum requirements. Further analysis showed significant differences between buildingswith lightweight timber construction and those with log construction. This can be due to fact that theairtightness has been predominantly measured in prefabricated buildings compared to on-site buildingtechnology. Surprisingly, the analysis showed no significant difference between buildings with a differentcompactness factor or a different number of storeys. For use in energy calculations, the base values ofair leakage rates for each group are calculated and presented accounting for variation of measurements.

Surface-groundwater interactions in karst: overview, concept and mapping

2021 ◽  
Author(s):  
Natasa Ravbar ◽  
Cyril Mayaud ◽  
Matej Blatnik ◽  
Metka Petrič
Keyword(s):  
Environmental Changes ◽  
Temporal Dynamics ◽  
Field Measurements ◽  
Spatial Dimension ◽  
Karst Aquifers ◽  
Wetland Ecosystems ◽  
Spatial And Temporal Dynamics ◽  
Ecohydrological Processes

<p>Under special meteorological and hydrological circumstances, shallow karst areas and karst poljes may experience surface water overflow. As a result, surface- groundwater interaction occurs usually creating intermittent lakes. Although human settlements and activities have traditionally adapted to these natural conditions, extensive temporary floods are classified among the most common natural disasters in karst. On the other hand, intermittent lakes are considered as natural reservoirs of excess recharge and good flood regulators in the lower parts of river basins. Due to specific ecohydrological processes and environmental conditions, these areas host unique wetland ecosystems with high levels of biodiversity and provide various ecosystem services, such as ecological productivity, photosynthesis and carbon storage. Given the dynamic nature of hydrological processes in karst aquifers, a distinctive feature of the phenomena described is its high variability of occurrence and duration. Therefore, the identification, characterization as well as the determination of the spatial dimension of flood levels is a challenging task. Focusing on the Slovenian karst, a literature review and analysis of topographical and hydrological data of the selected study areas was conducted. The hydrological analyses were based on long-term monitoring data from Slovenian Environmental Agency and partly on the authors' own database of field measurements and knowledge of the areas concerned. Consequently, the conceptual framework and the key criterion for the determination and recording of areas subject to temporary flooding were developed. A systematic survey reveals the significance of the extent, duration and frequency of flooding. Evaluation results are useful to designers of various water policies and management mechanisms for flood mitigation and protection of special habitats. Observing trends in the spatial and temporal dynamics of flood levels is also valuable for understanding how and to what extent karst aquifers are vulnerable to environmental changes. Finally, the analyses also enable prediction of the effects of these changes on other parts of the environment (e.g., hydrophilic habitats).</p>

scholarly journals Experimental Study on Dynamic Resilient Modulus of Lime-Treated Expansive Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zheng Lu ◽  
Yang Zhao ◽  
Shaohua Xian ◽  
Hailin Yao
Keyword(s):  
Moisture Content ◽  
Environmental Changes ◽  
Resilient Modulus ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
The Stability ◽  
Compaction Degree

Dynamic resilient modulus is the design index of highway subgrade design code in China, which is significantly affected by the traffic loads and environmental changes. In this study, dynamic triaxial tests were conducted to investigate the influence of moisture content, compaction degree, cyclic deviator stress, and confining pressure on lime-treated expansive soil. The suitability of UT-Austin model to lime-treated expansive soils was verified. The results indicate that the dynamic resilient modulus of lime-treated expansive soils increases nonlinearly with the increase of compaction degree, while decreases nonlinearly with the increase of dynamic stress level. The dynamic resilient modulus decreases linearly with the increase of moisture content and increases linearly with the increase of confining pressure. Moreover, the moisture content has a more significant effect on the dynamic resilient modulus of lime-treated expansive soil. Therefore, it is necessary to ensure the stability of soil humidity state and its excellent mechanical properties under long-term cyclic loading for the course of subgrade filling and service. Finally, the calculated results of the UT-Austin model for dynamic resilient modulus show a good agreement with the test results.

Decline in Natural Fisheries — A Genetic Analysis and Suggestion for Recovery

1986 ◽  
Vol 43 (6) ◽  
pp. 1298-1306 ◽  
Author(s):  
Giora W. Wohlfarth
Keyword(s):  
Negative Selection ◽  
Natural Waters ◽  
Environmental Changes ◽  
Monitoring Program ◽  
Fish Populations ◽  
Natural Environments ◽  
Direct Effects ◽  
Resident Population ◽  
Selection For ◽  
Bodies Of Water

Overfishing and pollution of the aquatic environment, in addition to their direct effects on natural fisheries, may have also influenced natural fish populations genetically. Overfishing drastically reduces population size and, since the larger individuals are selectively removed, is equivalent to selection for smaller sized fish. Adaptation of natural fish populations to their environment must have been reduced by rapid environmental changes resulting from pollution and infestation. Inbreeding, negative selection, and lack of adaption are here considered as the genetic causes for the decline of natural fisheries and lack of recovery. Restocking programs involving hatchery stocks are unlikely to solve this problem, since these stocks were selected for adaptation to hatchery environments and not to natural environments. A series of studies have demonstrated heterosis of interstrain crossbreds, mainly between hatchery and wild stocks of salmonids, for performance in natural waters. Two strategies could be implemented in restocking programs: stocking spawners of a domestic strain (preferably of one sex) for interbreeding with the resident population or direct stocking of crossbred fry. This should be tested in small isolated bodies of water and needs to be accompanied by a monitoring program in order to evaluate the results and minimize hazards.

scholarly journals The Western Maine Coastal Current reduces primary production rates, zooplankton abundance and benthic nutrient fluxes in Massachusetts Bay

2014 ◽  
Vol 71 (5) ◽  
pp. 1158-1169 ◽  
Author(s):  
M. Conor McManus ◽  
Candace A. Oviatt ◽  
Anne E. Giblin ◽  
Jane Tucker ◽  
Jefferson T. Turner
Keyword(s):  
Primary Production ◽  
Environmental Changes ◽  
Monitoring Program ◽  
Sediment Oxygen Demand ◽  
Nutrient Concentrations ◽  
Coastal Current ◽  
Zooplankton Abundance ◽  
Massachusetts Bay ◽  
Production Rates ◽  
Annual Primary Production

Abstract Primary production was measured from 1992–2010 in Massachusetts Bay and just outside Boston Harbor for the Massachusetts Water Resources Authority's outfall monitoring program. In 2003, annual primary production decreased by 221–278 g C m−2 year−1, with decreased rates continuing through 2010. Based on a conceptual model, oceanographic and meteorological variables were analysed with production rates to determine if concurrent environmental changes were responsible for the reduced primary production in Massachusetts Bay. Results indicated that a stronger influx of low salinity water from the Western Maine Coastal Current (WMCC) in recent years might be responsible for the decreases. The WMCC appeared to have become fresher due to increased river discharge in the western Gulf of Maine. Northeasterly winds in recent years promoted the WMCC intrusion into Massachusetts Bay. Correlation between primary production and surface salinities suggested an impact of the WMCC on production rates. We hypothesized that increased stratification resulted in reduced vertical mixing and reduced nutrient concentrations in surface waters for phytoplankton growth. However, no significant correlations were observed between the annual primary production and nutrient concentrations in Massachusetts Bay. Reduced production rates in Massachusetts Bay have, however, been associated with reduced zooplankton abundances, benthic ammonium fluxes and sediment oxygen demand in summer months.

Fatigue Monitoring and Life Extension for Top Tensioned Production Riser Systems

2021 ◽  
Author(s):  
Bulent Mercan ◽  
Mike Campbell ◽  
Clay Thompson
Keyword(s):  
Deep Water ◽  
Low Cost ◽  
Monitoring Program ◽  
Field Measurements ◽  
Fatigue Loading ◽  
Life Extension ◽  
Fatigue Monitoring ◽  
One Step ◽  
And Performance ◽  
The Impact

Abstract Top tensioned production riser (TTR) systems are exposed to fatigue loading in deep water as a result of vessel motions and high currents. The accuracy of predictions of the in-place fatigue response, which is a key input for any life extension requests, is dependent on the operating condition during the life of field including fluid contents and top tension. One solution to reduce this uncertainty is to deploy a fatigue monitoring system to assure the long-term integrity and performance of these riser systems. This paper presents results from a recent TTR monitoring campaign and focuses on the impact of top tension variation on riser motion and fatigue response in the field. Standalone and ROV deployable motion loggers offer a low cost and robust method of fatigue monitoring. The motion loggers are installed at discrete locations along the TTR to measure riser motions and then determine fatigue accumulations. During one of the recent monitoring campaigns, riser top tension was changed due to operational requirements, which in turn affected the riser fatigue response in the field. Field data is collected from two periods for two TTRs. The top tension was adjusted between each campaign allowing the effect of tension on riser fatigue response to be better understood using field measurements. The resulting riser motions and fatigue accumulations will be presented to demonstrate the sensitivity to top tension and highlight the importance of maintaining good records during the field life. Currently, there is no single guideline in the US that addresses TTR life-extension programs in detail. The results from this monitoring program are one step forward in better understanding system behavior of deep water TTRs and assessing the feasibility of an extended service life.

scholarly journals Reanalysis of multi-temporal aerial images of Storglaciären, Sweden (1959–99) – Part 1: Determination of length, area, and volume changes

2010 ◽  
Vol 4 (3) ◽  
pp. 333-343 ◽  
Author(s):  
T. Koblet ◽  
I. Gärtner-Roer ◽  
M. Zemp ◽  
P. Jansson ◽  
P. Thee ◽  
...  
Keyword(s):  
Mass Balance ◽  
Monitoring Program ◽  
Aerial Images ◽  
Aerial Photographs ◽  
Volume Changes ◽  
Front Position ◽  
Digital Elevation ◽  
Multi Temporal ◽  
The 1960S ◽  
Area And Volume

Abstract. Storglaciären, located in the Kebnekaise massif in northern Sweden, has a long history of glaciological research. Early photo documentations date back to the late 19th century. Measurements of front position variations and distributed mass balance have been carried out since 1910 and 1945/46, respectively. In addition to these in-situ measurements, aerial photographs have been taken at decadal intervals since the beginning of the mass balance monitoring program and were used to produce topographic glacier maps. Inaccuracies in the maps were a challenge to early attempts to derive glacier volume changes and resulted in major differences when compared to the direct glaciological mass balances. In this study, we reanalyzed dia-positives of the original aerial photographs of 1959, -69, -80, -90 and -99 based on consistent photogrammetric processing. From the resulting digital elevation models and orthophotos, changes in length, area, and volume of Storglaciären were computed between the survey years, including an assessment of related errors. Between 1959 and 1999, Storglaciären lost an ice volume of 19×106 m3, which corresponds to a cumulative ice thickness loss of 5.69 m and a mean annual loss of 0.14 m. This ice loss resulted largely from a strong volume loss during the period 1959–80 and was partly compensated during the period 1980–99. As a consequence, the glacier shows a strong retreat in the 1960s, a slowing in the 1970s, and pseudo-stationary conditions in the 1980s and 1990s.

scholarly journals THE USE OF REMOTE SENSING, REGRESSION QUANTILES, AND GIS APPROACHES FOR MODELING OF SCALLOP LARVAE: A Case Study in Funka Bay, Hokkaido, Japan

2011 ◽  
Vol 6 (2) ◽  
pp. 191
Author(s):  
I Nyoman Radiarta
Keyword(s):  
Remote Sensing ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Environmental Changes ◽  
Monitoring Program ◽  
Environmental Parameters ◽  
Sea Surface ◽  
Remotely Sensed Data ◽  
Funka Bay ◽  
Scallop Larvae

In the development of scallop cultivation in Japan, larvae collection and propagation become an important factor. Although the monitoring program has been conducted, modeling of species distribution is becoming an important tool for understanding the effects of environmental changes and resources management. This study was conducted to construct a model for providing estimation of the scallop larvae distribution in Funka Bay, Hokkaido, Japan using the integration of remote sensing, Regression Quantile (RQ) and Geographic Information System (GIS)-based model. Data on scallop larvae were collected during one year spawning season from April to July 2003. Environmental parameters were extracted from multi sensor remotely sensed data (chlorophyll-a and sea surface temperature) and a hydrographic chart (water depth). These parameters together with larvae data were then analyzed using RQ. Finally, spatial models were constructed within a GIS by combining the RQ models with digital map of environmental parameters. The results show that the model was best explained by using only sea surface temperature. The highest larvae densities were predicted in a relatively broad distribution along with the shallow water regions (Toyoura and Sawara to Yakumo) and the deeper water areas (center of the bay). The spatial model built from the RQ provided robust estimation of the scallop larvae distributions in the study area, as confirmed by model validation using independent data. These findings could contribute on the monitoring program in this region in order to distinguish the potential areas for an effective spat collection.

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