scholarly journals Effect of soil moisture content on the bearing capacity of small bored piles in the unsaturated soil of Maringá, Paraná, Brazil

2021 ◽  
Vol 337 ◽  
pp. 03006
Author(s):  
Verônica Ricken Marques ◽  
Antonio Belincanta ◽  
Mary-Antonette Beroya-Eitner ◽  
Jorge Luis Almada Augusto ◽  
Ewerton Guelssi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Bearing Capacity ◽  
Water Content ◽  
Unsaturated Soil ◽  
Soil Layer ◽  
Matric Suction ◽  
Load Test ◽  
Degree Of Saturation ◽  
Static Load Test

In this study, the influence of soil moisture on the bearing capacity of piles founded in an unsaturated clay soil was investigated. The soil studied, composing the upper soil layer in Maringá, Brazil, is lateritic, has degree of saturation between 37% and 70% and has collapsible behaviour when wet. The bearing capacity was determined by full-scale load tests following the Brazilian Standard for Static Load Test. Two pile lengths, 4 m and 8 m, were considered. To analyse the influence of soil moisture, two tests were performed for each pile length: one in soil in its natural moisture content and another in pre-moistened soil. Results show that for both pile lengths, an increase in water content caused a significant reduction in bearing capacity, which is attributed to the decrease in the matric suction of the soil. This is confirmed by the results of the initial evaluation made on the variation of matric suction and its contribution to the bearing capacity with changes in water content. In summary, this study confirms that the pile bearing capacity in unsaturated soil is dependent on soil water content, highlighting the fact that the approach of assuming full saturation condition in the evaluation of the pile bearing capacity in such soil may give erroneous results. Moreover, this study demonstrate that the empirical methods most commonly used in Brazil for pile bearing capacity determination, the Décourt & Quaresma and Aoki & Velloso methods, are overly conservative when applied to the Maringá soil.

scholarly journals ANALISIS PERBANDINGAN DAYA DUKUNG PONDASI TIANG PANCANG BERDASAR HASIL UJI SPT DAN PENGUJIAN DINAMIS

2020 ◽  
Vol 4 (1) ◽  
pp. 30
Author(s):  
Hinawan Teguh Santoso ◽  
Juandra Hartono
Keyword(s):  
Bearing Capacity ◽  
Soil Layer ◽  
Empirical Approach ◽  
Load Test ◽  
Test Results ◽  
Static Load Test ◽  
Bridge Construction ◽  
Friction Resistance ◽  
Concrete Piles ◽  
Central Java

<p><em>The foundation work is one of the main works in bridge construction. Failure of the foundation will be fatal for the entire bridge construction. Therefore, it is necessary to test the bearing capacity of the pile to determine the installed foundation capacity. The most accurate and most expensive method for determining the bearing capacity of a pile is a static load test, which is a full-scale trial method of giving a load 2 or 3 times greater than the designed load. Another method that is more economical and entirely accurate is using the High Strain Dynamics Pile Test (HSDPT) or often called the Pile Driving Analyzer (PDA) Test. This PDA test took a sample of 18 points of 600 mm diameter </em><em>pre-stressed concrete piles</em><em> on the Kaligawe Bridge located on Jalan Kaligawe KM 2+350, Semarang, Central Java. Based on the core drilling results, the soil layer was dominated by clay with an N-SPT value &lt; 30 to a depth of 45 meters. </em><em>The average bearing capacity of PDA test results is 432.4 tons or 0.4% greater when compared to the empirical approach based on N-SPT value (430.7 tons). The bearing capacity of the CAPWAP analysis is 401.0 tons or 7.3% less when compared to the PDA test, because the PDA test results are further processed using Signal Matching Analysis (SMA). CAPWAP analysis shows that the bearing capacity of piles is dominated by </em><em>friction resistance </em><em>by 71.7% and end resistance by 28.3% or by 4.4% difference when compared to the empirical approach, where the </em><em>friction resistance </em><em>value is 67.3% and end resistance is 32.7%. In general, it can be said that the PDA test is reliable enough to confirm the bearing capacity of the pile foundation that has been installed in the field.</em><em></em></p>

Influence of trees and topography on soil water content in semi-arid region, the case of an agro-silvo-pastoral ecosystem dominated by Faidherbia albida (Senegal)

2021 ◽  
Author(s):  
Djim Diongue ◽  
Didier Orange ◽  
Waly Faye ◽  
Olivier Roupsard ◽  
Frederic Do ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Layer ◽  
Rainfall Infiltration ◽  
Faidherbia Albida ◽  
Lower Slope ◽  
Upper Slope

&lt;p&gt;Vegetation strongly affects the water cycle, and the interactions between vegetation and soil moisture are fundamental for ecological processes in semiarid regions. Therefore, characterizing the variation in soil moisture is important to understand the ecological sustainability of cropping systems towards food security. The present study aims at exploring factors and mechanisms influencing soil moisture variability in the Faidherbia albida (FA) parkland at Sob basin located in the center of Senegal [1]. Volumetric soil moisture content at multiple depths was monitored at 15 locations distributed along a transect (upper slope, mid-slope and lower slope) and different FA tree position (under, at the limit and outside canopy) from August to October 2020. A portable TRIME Time Domain Reflectometry (TDR) Tube Probe (IMKO, Germany) was used to determine soil volumetric moisture content while being placed at specific depth intervals inside a PVC access tube set up at each location. Soil moisture was monitored at 10 cm interval from 20 to 420 cm during the rainy season from July to October 2020. Results of soil moisture profiles along the transects exhibit two main zones based on the standard deviation (SD) and the inflection of the coefficient of variation (CV): shallow soil moisture (SSM) and deep soil moisture (DSM). For SSM observed at 20-60 cm of the soil layer, both mean soil moisture and SD increase with depth, the lowest mean value (8%) being observed at the top surface. This soil layer is influenced by rainfall infiltration and daily evaporation. For DSM observed at 70-420 cm, the moisture pattern can be further divided into 4 soil sublayers taking the mean soil moisture vertical distribution as reference: (i) a rainfall infiltration layer (70-160 cm) which appears mainly influenced by cumulative rainfall infiltration in addition to transpiration of grassland and crops (shallow root system); (ii) a rainfall-transpiration layer (170-250 cm) which is still an infiltration layer but more influenced by crops transpiration; (iii) a transpiration layer (260-350 cm) which can be recharged by rainfall infiltration during heavy rainfall and supply deep root system; and (iv) deep transpiration layer (360-400 cm) which has DSM that can be influenced by extremely deep root vegetation such as FA. The factors influencing the soil water content varied with the topography. The soil water content SWC (mean and median value of 27.2 and 29.6% respectively) in the lower slope was significantly higher than that at middle (mean and median value of 14.4 and 13.2 % respectively) and upper slope (mean and median value of 16.8 and 18.4 % respectively). At last, soil water content was positively correlated with the distance from the FA, regardless the slope. The higher water content for both SSM and DSM was observed outside the FA canopy. This result refutes the initial hypothesis of higher SWC under trees and support a more detailed analysis of the infiltration capacity in relationship with the FA position.&lt;/p&gt;&lt;div&gt; &lt;div&gt; &lt;p&gt;[1] Faidherbia-Flux : https://lped.info/wikiObsSN/?Faidherbia-Flux&lt;/p&gt; &lt;/div&gt; &lt;/div&gt;

Aboveground Biomass of Reaumuria soongorica Shrub Effect on Soil Moisture and Nutrient Spatial Distribution in Arid and Semi-Arid Region

2013 ◽  
Vol 726-731 ◽  
pp. 3803-3806
Author(s):  
Bing Ru Liu ◽  
Jun Long Yang
Keyword(s):  
Spatial Distribution ◽  
Soil Moisture ◽  
Moisture Content ◽  
Aboveground Biomass ◽  
Soil Moisture Content ◽  
Plant Biomass ◽  
Soil Layer ◽  
Soil Nutrient ◽  
Desert Plant ◽  
Important Species

In order to revel aboveground biomass of R. soongorica shrub effect on soil moisture and nutrients spatial distribution, and explore mechanism of the changes of soil moisture and nutrients, soil moisture content, pH, soil organic carbon (SOC) and total nitrogen (TN) at three soil layers (0-10cm,10-20cm, and 20-40cm) along five plant biomass gradients of R. soongorica were investigated. The results showed that soil moisture content increased with depth under the same plant biomass, and increased with plant biomass. Soil nutrient properties were evidently influenced with plant biomass, while decreased with depth. SOC and TN were highest in the top soil layer (0-10 cm), but TN of 10-20cm layer has no significant differences (P < 0.05). Moreover, soil nutrient contents were accumulated very slowly. These suggests that the requirement to soil organic matter is not so high and could be adapted well to the desert and barren soil, and the desert plant R. soongorica could be acted as an important species to restore vegetation and ameliorate the eco-environment.

Prediction of Vertical Ultimate Bearing Capacity in Piles Based on the Improved Hyperbolic Model

2011 ◽  
Vol 250-253 ◽  
pp. 2271-2275
Author(s):  
Cheng Wang ◽  
Qi Zhang
Keyword(s):  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Load Test ◽  
Hyperbolic Model ◽  
Maximum Point ◽  
Static Load Test ◽  
Hyperbolic Curve ◽  
The Mathematical Model ◽  
Test Pile

Vertical static load test is widely used in the determination of pile bearing capacity, the mathematical model used to fit test pile data in determining the bearing capacity is essential. From the perspective of analytic geometry, the paper analyzes the traditional method of hyperbola, of which the asymptotic line of equilateral hyperbola was used to determine the ultimate bearing capacity. By extending the equal-axed conditions, a more general form of hyperbolic equation is derived and feasibility of such method is also analyzed, which indicates that the maximum point of curvature in such hyperbolic curve can determine the ultimate bearing capacity and such method is proved to be reasonable in practical projects.

scholarly journals Numerical investigation of wetting front migration and soil water distribution under vertical line source irrigation with different influencing factors

2021 ◽  
Author(s):  
Yanwei Fan ◽  
Liangjun Ma ◽  
Hujun Wei ◽  
Pengcheng Zhu
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Influencing Factors ◽  
Line Source ◽  
Vertical Line ◽  
Initial Water Content ◽  
Wetting Front ◽  
Simulation Results ◽  
Soil Wetting

Abstract Vertical line source irrigation (VLSI) is an underground irrigation method suitable for deep-rooted plants. Understanding the characteristics of the soil wetting body of the VLSI was the key to designing this irrigation system. On the basis of experimental verification of the reliability of the HYDRUS simulation results of VLSI under the conditions of soil texture (ST), initial water content (θi), line source buried depth (B), line source diameter (D) and line source length (L), numerical studies of the migration law of the wetting front of VLSI and the distribution characteristics of soil moisture were performed. The wetting front migration (WFM) was mainly influenced by ST, θi, D and L (P &lt; 0.05), while B had little effect on WFM (P &gt; 0.05). The shape of the soil wetting body changed little under different influencing factors. The water content contour was approximately ‘ellipsoidal’ around the line source. The soil moisture near the line source was close to the saturated moisture content. The moisture content around the line source gradually decreased outward, and the contour lines gradually became dense. According to the simulation results, a prediction model of multiple factors influencing the migration process of the VLSI wetting front was established. The predicted value was in good agreement with the measured value. The results of this research could provide a theoretical basis for further optimizing the combination of VLSI and irrigation elements.

scholarly journals Examination of the physical state of the soil under conventional and reduced tillage systems

2013 ◽  
pp. 183-186
Author(s):  
Géza Tuba
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Compaction ◽  
Soil Layer ◽  
Weather Conditions ◽  
Penetration Resistance ◽  
Conventional Tillage ◽  
Reduced Tillage ◽  
Deep Soil ◽  
Tillage Systems

he effect of reduced and conventional tillage systems on soil compaction and moisture content in two years with extreme weather conditions is introduced in this paper. The investigations were carried out in a long-term soil cultivation experiment set on a heavy textured meadow chernozem soil at the Karcag Research Institute. In 2010 the amount of precipitation during the vegetation period of winter wheat was 623.3 mm, 2.2 times higher than the 50-year average, while in 2011 this value was 188.7 mm giving only 65% of the average. The examinations were made after harvest on stubbles on 4 test plots in 5 replications in the case of each tillage system. Soil compaction was characterised by penetration resistance values, while the actual soil moisture contents were determined by gravimetry. The values of penetration resistance and soil moisture content of the cultivated soil layer were better in the case of reduced tillage under extreme precipitation conditions. It could be established that regular application of deep soil loosening is essential due to the formation of the unfavourable compact soil layer under 30 cm. Conventional tillage resulted in enhanced compaction under the depth of ploughing, the penetration resistance can reach the value of 4 MPa under wet, while even 8 MPa under dry soil status.

Root effects on soil water and hydraulic properties

Biologia ◽  
2007 ◽  
Vol 62 (5) ◽  
Author(s):  
Horst Gerke ◽  
Rolf Kuchenbuch
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
Root Effects

AbstractPlants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate on implications of non-capillary-bound root water for determination of soil moisture and calibration of soil hydraulic properties.In a field crop of maize (Zea mays) of 75 cm row spacing, we sampled the total soil volumes of 0.7 m × 0.4 m and 0.3 m deep plots at the time of tasseling. For each of the 84 soil cubes of 10 cm edge length, root mass and length as well as moisture content and soil bulk density were determined. Roots were separated in 3 size classes for which a mean root porosity of 0.82 was obtained from the relation between root dry mass density and root bulk density using pycnometers. The spatially distributed fractions of root water contents were compared with those of the water in capillary pores of the soil matrix.Water inside roots was mostly below 2–5% of total soil water content; however, locally near the plant rows it was up to 20%. The results suggest that soil moisture in roots should be separately considered. Upon drying, the relation between the soil and root water may change towards water remaining in roots. Relations depend especially on soil water retention properties, growth stages, and root distributions. Gravimetric soil water content measurement could be misleading and TDR probes providing an integrated signal are difficult to interpret. Root effects should be more intensively studied for improved field soil water balance calculations.

Numerical Analysis on the Bearing Capacity of Single Pile in Deep Excavation Area

2013 ◽  
Vol 671-674 ◽  
pp. 226-229
Author(s):  
Jun Jie Wu ◽  
Jin Jian Chen ◽  
Shuai Jun Liu ◽  
Jian Hua Wang
Keyword(s):  
Bearing Capacity ◽  
Large Scale ◽  
Numerical Study ◽  
Back Analysis ◽  
Load Test ◽  
Deep Excavation ◽  
Static Load Test ◽  
Fem Modeling ◽  
Vertical Bearing ◽  
Element Technique

Large-scale deep excavation may affect the bearing capacity of piles inside the excavation zone. It does not only cause the loss of friction, but also change the stress state of the subsoil. In this paper, nonlinear finite element technique is employed to investigate the bearing capacity of piles influenced by the deep excavation. Parameters of soil are obtained by back analysis on the pile static load test results. The bearing capacity of the piles during excavation is analyzed by performing FEM modeling under three conditions using the calibrated parameters. The numerical study shows that the loss ratio of vertical bearing capacity of pile foundation caused by excavation unloading is 34%.

Development of calibration algorithms for selected water content reflectometry probes for burned and non-burned organic soils of Alaska

2010 ◽  
Vol 19 (7) ◽  
pp. 961 ◽  
Author(s):  
Laura L. Bourgeau-Chavez ◽  
Gordon C. Garwood ◽  
Kevin Riordan ◽  
Benjamin W. Koziol ◽  
James Slawski
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Soil Profile ◽  
Soil Moisture Content ◽  
Mineral Soil ◽  
Organic Soil ◽  
Organic Content ◽  
Organic Soils ◽  
Probe Type

Water content reflectometry is a method used by many commercial manufacturers of affordable sensors to electronically estimate soil moisture content. Field‐deployable and handheld water content reflectometry probes were used in a variety of organic soil‐profile types in Alaska. These probes were calibrated using 65 organic soil samples harvested from these burned and unburned, primarily moss‐dominated sites in the boreal forest. Probe output was compared with gravimetrically measured volumetric moisture content, to produce calibration algorithms for surface‐down‐inserted handheld probes in specific soil‐profile types, as well as field‐deployable horizontally inserted probes in specific organic soil horizons. General organic algorithms for each probe type were also developed. Calibrations are statistically compared to determine their suitability. The resulting calibrations showed good agreement with in situ validation and varied from the default mineral‐soil‐based calibrations by 20% or more. These results are of particular interest to researchers measuring soil moisture content with water content reflectometry probes in soils with high organic content.

FULL SCALE STATIC LOAD TEST ON THE SPIDER NET SYSTEM

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
Helmy Darjanto ◽  
Masyhur Irsyam ◽  
Sri Prabandiyani Retno
Keyword(s):  
Bearing Capacity ◽  
Load Transfer ◽  
Static Load ◽  
Full Scale ◽  
Load Test ◽  
Static Load Test ◽  
Specific Element ◽  
Soil Stratum ◽  
Applied Loading ◽  
Shallow Footing

The Spider Net System Footing (SNSF) is a raft foundation system that commonly used in Indonesia. It contains a plate, downward ribs system for reinforcement, and the compacted filled soil. The ribs are in longitudinal and transversal, called as settlement rib and in diagonal direction, named as construction rib. This paper explores the load transfer mechanism along the plate, the ribs, filled soil and the base soil under the footing system. The mechanism is investigated by conducting full scale static load test on SNSF. Strain gauges were installed to monitor the strain increment of each footing elements during loading. 3D numerical analysis was also conducted to verify the experimental results. To analyze the results, Load-Ultimate Ratio Factor (L-URF) was proposed. L-URF was a ratio between ultimate soil bearing capacity of the SNSF and the applied loading at specific element. Higher the L-URF value means higher loading applied at its associate element. Both experimental and numerical results show that at the first stage the loading was fully carried out by the tip of the ribs and transferred to the soil stratum under the footing system. Increasing the loading, the ribs, plate, and filled soil altogether sustain the loading and then transferred to the soil stratum below the footing system. The results also affirm that SNSF generate higher bearing capacity compare with simple shallow footing.  

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