Experimental Research Based on the Optical Fiber Sensing Technology for a Jacked PHC Pipe Pile Penetration Process

The aim of this work is to explore the influence of the end resistance and shaft resistance regarding the mechanism for jacked pile penetration and the load-transfer rule during the penetration process. A full-scale field test was conducted in an actual project located in Dongying, Shandong Province, China. In this test, the axial strain experienced by two closed Prestressed High-strength Concrete (PHC) pipe piles during jacking into layered soil was monitored successfully using Fiber Bragg Grating (FBG) sensors mounted on the pile shaft. The experimental results show that FBG sensors have a good stability, strong antijamming performance, and can effectively monitor the pile stress. The variation law of the jacking force reflects the distribution of the soil layer, and the hardness of the soil layer at the pile end limits the pile force. When the pile end enters the silt layer from the clay layer, the jacking force and shaft resistance increase by 2.5 and 1.7, respectively. The shaft resistance accounted for 44.99% of the jacking force. The end resistance is affected by the mechanical properties of soil, and the end resistance of the silt layer is approximately twice that of the clay layer. The end resistance of the silt layer accounted for 59.84% of the jacking force. When the pile end enters the soft soil layer from the hard soil layer, the impact of the pile driving speed and the tangential force on the surface of the pile body must both be considered. During the pile penetration process, as the penetration depth increases, the radial stress on the pile side at a given depth is gradually released, while the shaft resistance at the pile side degrades significantly.

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PENGUKURAN RESISTIVITAS LAPISAN TANAH DI KELURAHAN TUAH KARYA MENGGUNAKAN KONFIGURASI SCHLUMBERGER

JOURNAL ONLINE OF PHYSICS ◽

10.22437/jop.v4i2.7578 ◽

2019 ◽

Vol 4 (2) ◽

pp. 11-14

Author(s):

Hafiza Mudral ◽

Usman Malik

Keyword(s):

Surface Water ◽

Soil Layer ◽

Clay Layer ◽

A Value ◽

Soil Constituent ◽

Housing Area ◽

Rock Structure ◽

Geoelectric Data ◽

Silt Layer ◽

Resistance Value

Geoelectric is one of the geophysical exploration methods that uses the earth's electrical properties to study subsurface conditions, the geoelectric method has several rules, one of which is Schlumberger's rule. This study aims to determine the composition of the soil layer, so that it can be known that the cause of difficult surface water seeps into the ground based on resistivity values at the HSB Indah Residence. Schlumberger configuration research uses a 300 meter stretch. Resistivity of soil constituent lithology in the study area was generated by processing geoelectric data using one-dimensional progress software. The cross section of the rock structure consists of five layers, namely the first layer is a clay layer with a resistivity value of 13.49 Ωm, the second layer is silt layer with a resistance value of 42.88 Ωm, the third layer is a clay layer with a value of 1.87 Ωm, the fourth layer is a layer of sandstone with a resistivity value of 59.17 Ωm and the fifth layer is a layer of gravel sand with a resistivity value of 443.40 Ωm. This shows that the cause of surface water is always flooded around the housing area, the soil layer is dominated by clay and silt material with a depth of more than 25 meters.

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Prospects of spring wheat cultivation in the conditions of arid Volga region

The Agrarian Scientific Journal ◽

10.28983/asj.y2020i5pp28-33 ◽

2020 ◽

pp. 28-33

Author(s):

Valery Genadievich Popov ◽

Andrey Vladimirovich Panfilov ◽

Yuriy Vyacheslavovich Bondarenko ◽

Konstantin Mikhailovich Doronin ◽

Evgeny Nikolaevih Martynov ◽

...

Keyword(s):

Spring Wheat ◽

Soil Layer ◽

Weather Conditions ◽

Volga Region ◽

Mineral Fertilizers ◽

Climate Conditions ◽

Wheat Cultivation ◽

Forest Belts ◽

Clear Differentiation ◽

The Impact

The article analyzes the experience of the impact of the system of forest belts and mineral fertilizers on the yield of spring wheat, including on irrigated lands. Vegetation irrigation is designed to maintain the humidity of the active soil layer from germination to maturation at the lower level of the optimum-70-75%, and in the phases of tubulation-earing - flowering - 75-80% NV. However, due to the large differences in zones and microzones of soil and climate conditions and due to the weather conditions of individual years, wheat irrigation regimes require a clear differentiation. In the Volga region in the dry autumn rainfalls give the norm of 800-1000 m3/ha, and in saline soils – 1000-1300 and 3-4 vegetation irrigation at tillering, phases of booting, earing and grain formation the norm 600-650 m3/ha. the impact of the system of forest belts, mineral fertilizers on the yield of spring wheat is closely tied to the formation of microclimate at different distances from forest edges.

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Organic mulching promotes soil organic carbon accumulation to deep soil layer in an urban plantation forest

Forest Ecosystems ◽

10.1186/s40663-020-00278-5 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Xiaodan Sun ◽

Gang Wang ◽

Qingxu Ma ◽

Jiahui Liao ◽

Dong Wang ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Content ◽

Fine Roots ◽

Soil Layer ◽

Carbon Accumulation ◽

Bulk Soil ◽

Organic Mulch ◽

The Impact ◽

Soc Fractions

Abstract Background Soil organic carbon (SOC) is important for soil quality and fertility in forest ecosystems. Labile SOC fractions are sensitive to environmental changes, which reflect the impact of short-term internal and external management measures on the soil carbon pool. Organic mulching (OM) alters the soil environment and promotes plant growth. However, little is known about the responses of SOC fractions in rhizosphere or bulk soil to OM in urban forests and its correlation with carbon composition in plants. Methods A one-year field experiment with four treatments (OM at 0, 5, 10, and 20 cm thicknesses) was conducted in a 15-year-old Ligustrum lucidum plantation. Changes in the SOC fractions in the rhizosphere and bulk soil; the carbon content in the plant fine roots, leaves, and organic mulch; and several soil physicochemical properties were measured. The relationships between SOC fractions and the measured variables were analysed. Results The OM treatments had no significant effect on the SOC fractions, except for the dissolved organic carbon (DOC). OM promoted the movement of SOC to deeper soil because of the increased carbon content in fine roots of subsoil. There were significant correlations between DOC and microbial biomass carbon and SOC and easily oxidised organic carbon. The OM had a greater effect on organic carbon fractions in the bulk soil than in the rhizosphere. The thinnest (5 cm) mulching layers showed the most rapid carbon decomposition over time. The time after OM had the greatest effect on the SOC fractions, followed by soil layer. Conclusions The frequent addition of small amounts of organic mulch increased SOC accumulation in the present study. OM is a potential management model to enhance soil organic matter storage for maintaining urban forest productivity.

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Earthworm Abundance Changes Depending on Soil Management Practices in Slovenian Vineyards

Agronomy ◽

10.3390/agronomy11061241 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1241

Author(s):

Stanko Vršič ◽

Marko Breznik ◽

Borut Pulko ◽

Jesús Rodrigo-Comino

Keyword(s):

Management Practices ◽

Human Impacts ◽

Soil Layer ◽

Soil Management ◽

Weather Conditions ◽

Soil Tillage ◽

Soil Biodiversity ◽

Straw Mulch ◽

Green Cover ◽

The Impact

Earthworms are key indicators of soil quality and health in vineyards, but research that considers different soil management systems, especially in Slovenian viticultural areas is scarce. In this investigation, the impact of different soil management practices such as permanent green cover, the use of herbicides in row and inter-row areas, use of straw mulch, and shallow soil tillage compared to meadow control for earthworm abundance, were assessed. The biomass and abundance of earthworms (m2) and distribution in various soil layers were quantified for three years. Monitoring and a survey covering 22 May 2014 to 5 October 2016 in seven different sampling dates, along with a soil profile at the depth from 0 to 60 cm, were carried out. Our results showed that the lowest mean abundance and biomass of earthworms in all sampling periods were registered along the herbicide strip (within the rows). The highest abundance was found in the straw mulch and permanent green cover treatments (higher than in the control). On the plots where the herbicide was applied to the complete inter-row area, the abundance of the earthworm community decreased from the beginning to the end of the monitoring period. In contrast, shallow tillage showed a similar trend of declining earthworm abundance, which could indicate a deterioration of soil biodiversity conditions. We concluded that different soil management practices greatly affect the soil’s environmental conditions (temperature and humidity), especially in the upper soil layer (up to 15 cm deep), which affects the abundance of the earthworm community. Our results demonstrated that these practices need to be adapted to the climate and weather conditions, and also to human impacts.

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Influence of Slope Direction on the Soil Seed Bank and Seedling Regeneration of Castanopsis hystrix Seed Rain

Forests ◽

10.3390/f12040500 ◽

2021 ◽

Vol 12 (4) ◽

pp. 500

Author(s):

Zong Zhao ◽

Yong Liu ◽

Hongyan Jia ◽

Wensheng Sun ◽

Angang Ming ◽

...

Keyword(s):

Seed Bank ◽

Temporal Dynamics ◽

Soil Seed Bank ◽

Soil Layer ◽

Seed Rain ◽

Seed Vigor ◽

Study Results ◽

The Impact ◽

Mature Seeds

Objective: To investigate the impact of different slope directions on the quantity and quality of the soil seed bank and seedling germination process of Castanopsis hystrix plantations. Method: Fixed sample plots in forest stands of Castanopsis hystrix were established on different slope directions (sunny slope, semi-sunny slope, semi-shady slope, and shady slope). The characteristics of the forest stand were investigated, and per-wood scaling was carried out. The temporal dynamics of the seed rain and seed bank were quantified using seed rain collectors and by collecting soil samples from different depths. The quantity and quality of the seeds were determined, and the vigor of mature seeds was measured throughout the study. Results: (1) The diffusion of Castanopsis hystrix seed rain started in mid-September, reached its peak from late October to early November, and ended in mid-December. (2) The dissemination process, occurrence time, and composition of the seed rain varied between the different slope directions. The seed rain intensity on the semi-sunny slope was the highest (572.75 ± 9.50 grains∙m−2), followed by the sunny slope (515.60 ± 10.28 grains∙m−2), the semi-shady slope (382.13 ± 12.11 grains∙m−2), and finally the shady slope (208.00 ± 11.35 grains∙m−2). The seed rain on the sunny slope diffused earliest and lasted the longest, while the seed rain on the shady slope diffused latest and lasted the shortest time. Seed vigor and the proportion of mature seeds within the seed rain were greatest on the semi-sunny slope, followed by the sunny slope, semi-shady slope, and the shady slope. (3) From the end of the seed rain to August of the following year, the amount of total reserves of the soil seed banks was highest on the semi-sunny slope, followed by the sunny slope then the semi-shady slope, and it was the lowest on the shady slope. The amount of mature, immature, gnawed seeds and seed vigor of the soil seed bank in various slope directions showed a decreasing trend with time. The seeds of the seed bank in all slope directions were mainly distributed in the litter layer, followed by the 0–2 cm humus layer, and only a few seeds were present in the 2–5 cm soil layer. (4) The seedling density of Castanopsis hystrix differed significantly on the different slope directions. The semi-sunny slope had the most seedlings, followed by the sunny slope, semi-shady slope, and the shady slope. Conclusions: The environmental conditions of the semi-sunny slope were found to be most suitable for the seed germination and seedling growth of Castanopsis hystrix, and more conducive to the regeneration and restoration of its population.

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The Impact of Error Accounting in a Bayesian Approach to Calibrating Modeled Turbulent Fluxes in an Open-Canopy Forest

Journal of Hydrometeorology ◽

10.1175/jhm-d-17-0030.1 ◽

2017 ◽

Vol 18 (7) ◽

pp. 2029-2042

Author(s):

Tony E. Wong ◽

William Kleiber ◽

David C. Noone

Keyword(s):

Markov Chain ◽

Land Surface ◽

Hydrological Modeling ◽

Soil Layer ◽

Turbulent Fluxes ◽

Surface Model ◽

Model Parameters ◽

Top Soil ◽

The Impact ◽

Calibration Approach

Abstract Land surface models are notorious for containing many parameters that control the exchange of heat and moisture between land and atmosphere. Properly modeling the partitioning of total evapotranspiration (ET) between transpiration and evaporation is critical for accurate hydrological modeling, but depends heavily on the treatment of turbulence within and above canopies. Previous work has constrained estimates of evapotranspiration and its partitioning using statistical approaches that calibrate land surface model parameters by assimilating in situ measurements. These studies, however, are silent on the impacts of the accounting of uncertainty within the statistical calibration framework. The present study calibrates the aerodynamic, leaf boundary layer, and stomatal resistance parameters, which partially control canopy turbulent exchange and thus the evapotranspiration flux partitioning. Using an adaptive Metropolis–Hastings algorithm to construct a Markov chain of draws from the joint posterior distribution of these resistance parameters, an ensemble of model realizations is generated, in which latent and sensible heat fluxes and top soil layer temperature are optimized. A set of five calibration experiments demonstrate that model performance is sensitive to the accounting of various sources of uncertainty in the field observations and model output and that it is critical to account for model structural uncertainty. After calibration, the modeled fluxes and top soil layer temperature are largely free from bias, and this calibration approach successfully informs and characterizes uncertainty in these parameters, which is essential for model improvement and development. The key points of this paper are 1) a Markov chain Monte Carlo calibration approach successfully improves modeled turbulent fluxes; 2) ET partitioning estimates hinge on the representation of uncertainties in the model and data; and 3) despite these inherent uncertainties, constrained posterior estimates of ET partitioning emerge.

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Influence of pore water pressure change on consolidation behavior of saturated poroelastic medium

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-382-375-2020 ◽

2020 ◽

Vol 382 ◽

pp. 375-379

Author(s):

Chao-Lung Yeh ◽

Wei-Cheng Lo ◽

Cheng-Wei Lin ◽

Chung-Feng Ding

Keyword(s):

Pore Water ◽

Pore Water Pressure ◽

Saturated Porous Medium ◽

Water Pressure ◽

Soil Layer ◽

Pressure Change ◽

Clay Layer ◽

Poroelastic Medium ◽

Total Settlement ◽

Consolidation Behavior

Abstract. There are many factors causing land subsidence, and groundwater extraction is one of the most important causes of subsidence. A set of coupled partial differential equations are derived in this study by using the poro-elasticity theory and linear stress-strain constitutive relation to describe the one-dimensional consolidation in a saturated porous medium subjected to pore water pressure change due to groundwater table depression. Simultaneously, the closed-form analytical solutions for excess pore water pressure and total settlement are obtained. To illustrate the consolidation behavior of the poroelastic medium, the saturated layer of clay sandwiched between two sand layers is simulated, and the dimensionless pore water pressure changes with depths and the dimensionless total settlement as function of time in the clay layer are examined. The results show that the greater the water level change in the upper and lower sand layers, the greater the pore water pressure change and the total settlement of the clay layer, and the more time it takes to reach the steady state. If the amount of groundwater replenishment is increased, the soil layer will rebound.

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The role of unpaved roads in the formation of landslide processes (on the example of Voronezh region)

RUDN Journal of Ecology and Life Safety ◽

10.22363/2313-2310-2020-28-1-65-74 ◽

2020 ◽

Vol 28 (1) ◽

pp. 65-74

Author(s):

Andrey N. Timofeev

Keyword(s):

Soil Layer ◽

Anthropogenic Activity ◽

Unpaved Roads ◽

Erosion Processes ◽

Voronezh Region ◽

Landslide Processes ◽

Landslide Process ◽

The Impact ◽

Landslide Distribution

The article gives a brief description of the Voronezh region, provides data on the cause of landslides in its territory. The cyclical nature of landslide processes is noted, which in the region is on average 6-8 years. Attention is focused on anthropogenic activity, leading to the occurrence of creeping layers of the earth. The main causes of erosion processes are: significant plowing of the area (80%), which is not subject to the rules of anti-erosion agrotechnology; the irrational use of pastures and hayfields; an extensive gully-beam network. The role of temporary reservoirs formed in the ruts of unpaved roads, passing along the slopes and ravines, as a source of overmoistening of the soil layers and initiation of landslide processes is considered. The analysis of the landslide distribution over the territory of the Voronezh region and their dependence on the network of dirt roads is given. The areas of the Voronezh region were ranked by the number of landslide processes associated with the impact of a number of unpaved highways. Of the 32 districts of the region, according to this ranking, 12 are extremely dangerous, very dangerous and dangerous, and the same areas have a very extensive network of unpaved roads running near ravines, steep banks of rivers and ponds, where potentially flow of landslide processes. Dirt roads often have relatively deep ruts where melted or rainwater accumulates, forming local micro-ponds. Flowing to the waterproof layer, water saturates the soil layer, which can slide down the slope, forming a landslide process. It is necessary to predict the possibility of the occurrence of dangerous natural phenomena when laying automobile dirt roads.

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Study on the Optimal Groove Shape and Glue Material for Fiber Bragg Grating Measuring Bolts

Sensors ◽

10.3390/s18061799 ◽

2018 ◽

Vol 18 (6) ◽

pp. 1799 ◽

Cited By ~ 6

Author(s):

Yiming Zhao ◽

Nong Zhang ◽

Guangyao Si ◽

Xuehua Li

Keyword(s):

Fiber Bragg Grating ◽

Linear Regression Analysis ◽

Tensile Load ◽

Tensile Tests ◽

Bragg Grating ◽

Engineering Practice ◽

Direct Tension ◽

Groove Shape ◽

Fbg Sensors ◽

The Impact

Fiber Bragg grating (FBG) measuring bolts, as a useful tool to evaluate the behaviors of steel bolts in underground engineering, can be manufactured by gluing the FBG sensors inside the grooves, which are usually symmetrical cuts along the steel bolt rod. The selection of the cut shape and the glue types could perceivably affect the final supporting strength of the bolts. Unfortunately, the impact of cut shape and glue type on bolting strength is not yet clear. In this study, based on direct tension tests, full tensile load–displacement curves of rock bolts with different groove shapes were obtained and analyzed. The effects of groove shape on the bolt strength were discussed, and the stress redistribution in the cross-section of a rock bolt with different grooves was simulated using ANSYS. The results indicated that the trapezoidal groove is best for manufacturing the FBG bolt due to its low reduction of supporting strength. Four types of glues commonly used for the FBG sensors were assessed by conducting tensile tests on the mechanical testing and simulation system and the static and dynamic optical interrogators system. Using linear regression analysis, the relationship between the reflected wavelength of FBG sensors and tensile load was obtained. Practical recommendations for glue selection in engineering practice are also provided.

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Analysis of hypervelocity impacts: The tungsten case

Nuclear Fusion ◽

10.1088/1741-4326/ac42f6 ◽

2021 ◽

Author(s):

A Fraile ◽

Prashant Dwivedi ◽

Giovanni Bonny ◽

Tomas Polcar

Keyword(s):

Kinetic Energy ◽

Interatomic Potential ◽

Detailed Examination ◽

Penetration Process ◽

Damage Initiation ◽

Crater Size ◽

Crater Volume ◽

Parallel Molecular Dynamics ◽

Dynamics Simulations ◽

The Impact

Abstract The atomistic mechanisms of damage initiation during high velocity (v up to 9 km/s, kinetic energies up to 200 keV) impacts of W projectiles on a W surface have been investigated using parallel molecular-dynamics simulations involving large samples (up to 40 million atoms). Various aspects of the impact at high velocities, where the projectile and part of the target materials undergo massive plastic deformation, breakup, melting, and vaporization, are analyzed. Different stages of the penetration process have been identified through a detailed examination of implantation, crater size and volume, sputtered atoms, and dislocations created by the impacts. The crater volume increases linearly with the kinetic energy for a given impactor; and the total dislocation length increases with the kinetic energy but depends itself on the size of the impactor. Furthermore, the total dislocation length is less dependent of the fine details of the interatomic potential. The results are rationalized based on the physical properties of bcc W.

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