scholarly journals Effects of repeated hydraulic loads on microstructure and hydraulic behaviour of a compacted clayey silt

2020 ◽  
Vol 57 (1) ◽  
pp. 100-114 ◽  
Author(s):  
Arash Azizi ◽  
Guido Musso ◽  
Cristina Jommi
Keyword(s):  
Hydraulic Conductivity ◽  
Construction Projects ◽  
Water Retention ◽  
Construction Material ◽  
Experimental Tests ◽  
Climatic Conditions ◽  
Earth Construction ◽  
Hydraulic Behaviour ◽  
Clayey Silt ◽  
The Impact

Soils used in earth construction projects are mostly unsaturated, and they undergo frequent drying–wetting cycles (repeated hydraulic loads) due to changes in climatic conditions or variations of the ground water level, particularly at shallow depths. After compaction, changes in water content can significantly influence the hydromechanical response of the construction material, which therefore must be assessed for repeated hydraulic loads. This research investigates the effect of such loads on the microstructure and hydraulic behaviour of a silty soil, typically used in the construction of embankments and dykes, with the aim of providing a better understanding of the consequences of drying–wetting cycles on the response of the material over time. Experimental tests were performed to study the impact of drying–wetting cycles on the water retention, hydraulic conductivity, and fabric of compacted specimens. Fabric changes are documented to take place even without significant volumetric strains, promoting an irreversible increase in the hydraulic conductivity and a reduction in the capacity to retain water compared to the as-compacted soil. The fabric changes are interpreted and quantified by means of a hydromechanical model, which accounts for the evolving pore-size distribution at different structural levels. The proposed model reproduces quite well the microstructural observations, together with the evolution of the water retention behaviour and hydraulic conductivity.

scholarly journals Effects of Neglecting PCM Hysteresis While Making Simulation Calculations of a Building Located in Polish Climatic Conditions

2021 ◽  
Vol 11 (19) ◽  
pp. 9166
Author(s):  
Anna Zastawna-Rumin ◽  
Katarzyna Nowak
Keyword(s):  
Surface Temperature ◽  
Phase Change ◽  
Phase Change Materials ◽  
Model Building ◽  
Experimental Tests ◽  
Climatic Conditions ◽  
Heat Accumulation ◽  
Noticeable Effect ◽  
Change Temperature ◽  
The Impact

The use of phase change materials (PCM) in different building applications is a hot topic in today’s research and development activities. Numerous experimental tests confirmed that the hysteresis of the phase change process has a noticeable effect on heat accumulation in PCM. The authors are trying to answer the question of whether the neglecting of hysteresis or the impact of the speed of phase transformation processes reduce the accuracy of the simulation. The analysis was performed for a model building, created to validate the energy calculations. It was also important to conduct simulations for the polish climatic conditions. The calculations were conducted for three variants of materials. In addition, in the case of models containing layers with PCM, calculations were made both taking into account, as well as excluding material hysteresis in the calculations. In the analyzed examples, after taking into account hysteresis in the calculations, the period of time when surface temperature is below the phase change temperature of the materials decreased by 10.6% and 29.4% between 01 June to 30 September, for the options with PCM boards and Dupont boards, respectively. Significant differences in surface temperature were also observed. The effects of neglecting, even relatively small hysteresis, in the calculations are noticeable and can lead to significant errors in the calculation.

scholarly journals Impact of Root Growth on the Physical Properties of Peat Substrate under a Constant Water Regimen

HortScience ◽  
2011 ◽  
Vol 46 (10) ◽  
pp. 1394-1399 ◽  
Author(s):  
Patrice Cannavo ◽  
Houda Hafdhi ◽  
Jean-Charles Michel
Keyword(s):  
Hydraulic Conductivity ◽  
Root Growth ◽  
Water Potential ◽  
Water Retention ◽  
Total Porosity ◽  
Unsaturated Hydraulic Conductivity ◽  
Shoot Weight ◽  
The Impact ◽  
New Guinea Impatiens ◽  
Water Holding

The impact of root growth on the hydraulic properties of peat substrate was investigated under optimal water retention, i.e., at a constant water potential of –1 kPa. ‘New Guinea’ impatiens was grown in 1.1-L cylindrical containers for 196 d in a greenhouse under controlled climate and fertilization conditions. Water retention and hydraulic conductivity curves, root biomass and volume, and shoot weight were measured. Results indicated a maximal root volumetric content of 0.065 m3·m−3 that was as high as the peat content in containers (0.068 m3·m−3). From Day 0 to Day 196, the total porosity of the growing media decreased from 0.931 m3·m−3 to 0.874 m3·m−3. Moreover, considering the water-holding capacity at a water potential of –1 kPa, it increased from 0.58 to 0.75 m3·m−3 (i.e., by 29.3%) without changes in water availability but with a large decrease in air-filled porosity from 0.35 to 0.14 m3·m−3. The unsaturated hydraulic conductivity K(θ) decreased as a result of root growth. Root growth also modified pore size distribution and pore structure. Hydraulic conductivity curves indicated a better pore connectivity reflected by a decrease in tortuosity.

The impact of heating on the hydraulic properties of soils sampled under different plant cover

Biologia ◽  
2009 ◽  
Vol 64 (3) ◽  
Author(s):  
Viliam Novák ◽  
Ľubomír Lichner ◽  
Bin Zhang ◽  
Karol Kňava
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Water Drop ◽  
Sampling Site ◽  
Water Repellency ◽  
Saturated Hydraulic Conductivity ◽  
Soil Water Repellency ◽  
The Impact ◽  
Penetration Time

AbstractThe impact of heating on the peristence of water repellency, saturated hydraulic conductivity, and water retention characteristics was examined on soils from both forest and meadow sites in southwest Slovakia shortly after a wet spell. The top 5 cm of meadow soils had an initial water drop penetration time WDPT at 20°C of 457 s, whereas WDPT in the pine forest was 315 s for the top 5 cm and 982 s if only the top 1 cm was measured. Heating soils at selected temperatures of 50, 100, 150, 200, 250 and 300°C caused a marked drop in water drop penetration time WDPT from the initial value at 20°C. However, samples collected in different years and following an imposed cycle of wetting and drying showed much different trends, with WDPT sometimes initially increasing with temperature, followed by a drop after 200–300°C. The impact of heating temperature on the saturated hydraulic conductivity of soil was small. It was found for both the drying and wetting branches of soil water retention curves that an increase in soil water repellency resulted in a drop in soil water content at the same matric potential. The persistence of soil water repellency was strongly influenced by both the sampling site and time of sampling, as it was characterized by the results of WDPT tests.

Influence of peatmoss on hydraulic properties and strength of compacted soils

2004 ◽  
Vol 84 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Osama K. Nusier
Keyword(s):  
Organic Matter ◽  
Hydraulic Conductivity ◽  
Water Retention ◽  
Sandy Loam ◽  
Organic Matter Content ◽  
Saturated Hydraulic Conductivity ◽  
Modulus Of Rupture ◽  
Compacted Soils ◽  
Available Water ◽  
The Impact

Due to its high organic matter content, peatmoss can be highly beneficial to agricultural soil. In this research, the impact of varying organic matter contents at different compaction efforts on water retention, saturated hydraulic conductivity, and modulus of rupture of three soils (sandy loam, clay loam, and clay) has been investigated under laboratory conditions. Compaction changed the ability of the soils to hold water, increased modulus of rupture, and decreased the plant-available water-holding capacity of the soils. On the other hand, organic matter generally increased the ability of the soils to hold water, expanded the available water capacity, and decreased the modulus of rupture of compacted soils. Key words: Peatmoss, water retention, saturated hydraulic conductivity, modulus of rupture

scholarly journals Impacts Of Environment On Building Construction Projects On Woliata Sodo Town

2022 ◽  
Vol 24 (1) ◽  
pp. 93-104
Author(s):  
Wudnesh Honja Angeloa ◽  
Keyword(s):  
Environmental Impacts ◽  
Environmental Conditions ◽  
Construction Projects ◽  
Construction Material ◽  
Research Result ◽  
Productivity Loss ◽  
Construction Materials ◽  
Building Construction ◽  
Development Economic ◽  
The Impact

The environmental impacts have become a series of problems in today’s construction environments. Environmental conditions can have an adverse impact on the duration, cost, and quality of construction activities. This study is conducted to describe and point out the impact of the environment on building construction projects in sodo town. The contractor can estimate the Productivity loss due to the impact of environment on construction activity can be either partial or complete: partial loss is generally attributed to reduced labor productivity and work stoppage which interrupt those activities. This study organized by using questioners. The research basically focused on identifying and quantifying different environmental impacts that can affect the construction progresses. As the research result the escalation of construction material price, the availability of construction materials around the area and the involvement of different construction parties and the climatic condition of the environments are the main findings that we have got from our analysis. Generally, this research guides to meet future demands for sustainable environmental development, economic development, expansion of different construction infrastructure for sodo town. Many contractors found in this area fall over different environmental challenges. So to overcome these problems, are some requirements expected from different parties. To minimize those environmental impacts the construction parties should make a detail feasible study about the overall environmental conditions of sodo town before they decided to start up any construction works.

scholarly journals Effect of Unimodal and Bimodal Soil Hydraulic Properties on Slope Stability Analysis

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1674
Author(s):  
Hsin-Fu Yeh ◽  
Tsien-Ting Huang ◽  
Jhe-Wei Lee
Keyword(s):  
Hydraulic Conductivity ◽  
Slope Stability ◽  
Water Content ◽  
Water Retention ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Seepage Analysis ◽  
Hydraulic Behavior ◽  
Conductivity Function ◽  
The Impact

Rainfall infiltration is the primary triggering factor of slope instability. The process of rainfall infiltration leads to changes in the water content and internal stress of the slope soil, thereby affecting slope stability. The soil water retention curve (SWRC) was used to describe the relationship between soil water content, matric suction, and the water retention characteristics of the soil. This characteristic is essential for estimating the properties of unsaturated soils, such as unsaturated hydraulic conductivity function and shear strength. Thus, SWRC is regarded as important information for depicting the properties of unsaturated soil. The SWRC is primarily affected by the soil pore size distribution (PSD) and has unimodal and bimodal features. The bimodal SWRC is suitable for soils with structural or dual-porous media. This model can describe the structure of micropores and macropores in the soil and allow the hydraulic behavior at different pore scales to be understood. Therefore, this model is more consistent with the properties of onsite soil. Few studies have explored the differences in the impact of unimodal and bimodal models on unsaturated slopes. This study aims to consider unimodal and bimodal SWRC to evaluate the impact of unsaturated slope stability under actual rainfall conditions. A conceptual model of the slope was built based on field data to simulate changes in the hydraulic behavior of the slope. The results of seepage analysis show that the bimodal model has a better water retention capacity than the unimodal model, and therefore, its water storage performance is better. Under the same saturated hydraulic conductivity function, the wetting front of the bimodal model moves down faster. This results in changes in the pressure head, water content, and internal stress of the soil. The results show that the water content and suction stress changes of the bimodal model are higher than those of the unimodal model due to the difference in water retention capacity. Based on the stability of the slope, calculated using the seepage analysis, the results indicate that the potential failure depth of the bimodal model is deeper than that of the unimodal model.

Drivers and their Relationship with Inhibitors Influencing the Adoption of Stabilized Earth Construction to Alleviate Urban Housing Crisis in Zimbabwe

2014 ◽  
Vol 632 ◽  
pp. 119-144 ◽  
Author(s):  
Mohammad Sharif Zami
Keyword(s):  
Construction Projects ◽  
Low Cost ◽  
Construction Material ◽  
Urban Housing ◽  
Housing Crisis ◽  
African Countries ◽  
Interview Method ◽  
Earth Construction ◽  
Widespread Adoption ◽  
To Come

Addressing urban housing crisis is an enormous challenge for most of the African countries due to the increasing cost of the building material. Zimbabwe is no exception having the same challenges with urban housing crisis. As a matter of fact the conventional construction material is not affordable considering the current economic hardship faced by the majority Zimbabweans. Therefore, an appropriate alternative construction material and technique is essential which can alleviate urban housing crisis in Zimbabwe. The success of the experimented stabilised earth construction projects of urban houses in Zimbabwe widens avenues considering this construction material as an appropriate alternative to the conventional ones and finding out the potential drivers that can help adoption of this technology. This paper aims to refine the drivers and establish its interrelationship with inhibitors with the help of in-depth interview method. First, a critical literature review method is used to come up with a generic list the inhibitors and drivers influencing the adoption of this technology. Second, the identified inhibitors and drivers refined through a series of in-depth interviews to establish drivers and inhibitors influencing the widespread adoption of stabilised earth to address urban low cost housing crisis in Zimbabwe. Third, the analysis of drivers and inhibitors interrelationship understand show the widespread adoption of stabilised earth construction can alleviate urban housing crisis in Zimbabwe.

scholarly journals Characterization of stony soils' hydraulic conductivity using laboratory and numerical experiments

2015 ◽  
Vol 2 (2) ◽  
pp. 1103-1133
Author(s):  
M. Pichault ◽  
E. Beckers ◽  
A. Degré ◽  
S. Garré
Keyword(s):  
Hydraulic Conductivity ◽  
Water Flow ◽  
Numerical Experiments ◽  
Saturated Hydraulic Conductivity ◽  
Rock Fragments ◽  
Hydraulic Behaviour ◽  
Unsaturated Hydraulic Conductivity ◽  
The One ◽  
The Impact

Abstract. Determining soil hydraulic properties is of major concern in various fields of study. Though stony soils are widespread across the globe, most studies deal with gravel-free soils so that the literature describing the impact of stones on soil's hydraulic conductivity is still rather scarce. Most frequently, models characterizing the saturated hydraulic conductivity of stony soils assume that the only effect of rock fragments is to reduce the volume available for water flow and therefore they predict a decrease in hydraulic conductivity with an increasing stoniness. The objective of this study is to assess the effect of rock fragments on the saturated and unsaturated hydraulic conductivity. This was done by means of laboratory and numerical experiments involving different amounts and types of coarse fragments. We compared our results with values predicted by the aforementioned models. Our study suggests that considering that stones only reduce the volume available for water flow might be ill-founded. We pointed out several drivers of the saturated hydraulic conductivity of stony soils, not considered by these models. On the one hand, the shape and the size of inclusions may substantially affect the hydraulic conductivity. On the other hand, the presence of rock fragments can counteract and even overcome the effect of a reduced volume in some cases. We attribute this to the creation of voids at the fine earth-stone interface. Nevertheless, these differences are mainly important near to saturation. However, we come up with a more nuanced view regarding the validity of the models under unsaturated conditions. Indeed, under unsaturated conditions, the models seem to represent the hydraulic behaviour of stones reasonably well.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

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