Measuring soil pressure within a soil mass

2013 ◽  
Vol 50 (7) ◽  
pp. 716-722 ◽  
Author(s):  
Mark Talesnick
Keyword(s):  
Particle Size ◽  
Soil Type ◽  
Soil Mechanics ◽  
Pressure Sensors ◽  
Soil Mass ◽  
Soil Pressure ◽  
Stress History ◽  
Pressure System ◽  
Highly Nonlinear ◽  
Type Particle

Reliable measurement of pressure within a particulate media has frustrated researchers in the field of soil mechanics and soil structure interaction for many years. The difficulty stems from the fact that most sensing systems involve compliance in the measurement concept. This compliance imparts a parasitic output to the measurement. In the past, researchers have attempted to calibrate this disturbance. Research has demonstrated that calibrations of this sort are dependent upon soil type, particle size, sensor geometry, and soil stiffness. Response of such sensors has been shown to be stress history–dependent: the response upon unloading may be highly nonlinear, resulting in a high degree of hysteresis. Complications in the measurement of soil pressure within a soil mass are significantly more complex from those met in the measurement of soil pressure at a structural boundary and must be considered separately. This paper utilizes a concept called the Null Soil Pressure System. Null pressure sensors were embedded and tested in a series of uniformly graded soils with particle diameters ranging from less than 0.15 to 15 mm. The data indicates that the response of the null pressure sensor consistently exceeds the actual soil pressure by a value of 4% ± 3%. This outcome is seen to be independent of soil type, particle size, stiffness, and stress history. No hysteresis is noted between loading and unloading, and additional loading cycles align with that of the virgin loading segment.

Impact of Biochar on Water Holding Capacity of Two Chinese Agricultural Soil

2014 ◽  
Vol 941-944 ◽  
pp. 952-955 ◽  
Author(s):  
Dao Yuan Wang ◽  
Deng Hua Yan ◽  
Xin Shan Song ◽  
Hao Wang
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Soil Type ◽  
Agricultural Soil ◽  
Water Retention ◽  
Water Holding Capacity ◽  
Walnut Shell ◽  
Retention Characteristics ◽  
Water Holding

Adding biochar to agricultural soil has been suggested as an approach to enhance soil carbon sequestration. Biochar has also been used as a soil amendment to reduce nutrient leaching, reduce soil acidity and improve water holding capacity. Walnut shells and woody material are waste products of orchards that are cheap, carbon-rich and good feedstock for production of biochar. The effectiveness of biochar as an amendment varies considerably as a function of its feedstock, temperature during pyrolysis, the biochar dose to soil, and mechanical composition. Biochar was produced from pyrolysis of walnut shell at 900 °C and soft wood at 600 to 700 °C. We measured the effect of these different parameters in two types of agricultural soil in Jilin and Beijing, China, a silt clay loam and a sandy loam, on the soils’ particle size distribution and water retention characteristics. Biochars with two different doses were applied to each soil type. Soil field capacity and permanent wilting point were measured using a pressure plate extractor for each combination of biochar and soil type. The results show that the effect of biochar amendment on soil water retention characteristics depend primarily on soil particle size distribution and surface characteristics of biochar. High surface area biochar can help raise the water holding capacity of sandy soil.

scholarly journals BASIS OF MATHEMATICAL INTERACTION MODELS OF WHEEL PROPELLERS OF FORESTRY MACHINES WITH SLIDING SURFACES

2020 ◽  
Vol 10 (1) ◽  
pp. 173-184
Author(s):  
Olga Burmistrova ◽  
Elena Teterevleva ◽  
Igor Grigorev ◽  
O. Kunitskaya ◽  
Andrey Manukovskiy ◽  
...  
Keyword(s):  
Soil Mechanics ◽  
Physical And Mechanical Properties ◽  
Soil Mass ◽  
Contact Spot ◽  
Time Value ◽  
Partial Load ◽  
Forestry Production ◽  
The Impact ◽  
Number Of Passes ◽  
Contact Spots

The purpose of the research, the results of which are presented in this article, is to analyze the scientific description of the properties of weak bearing movement surfaces of forest machines. The analysis has showed that universal mathematical models of the wheel propeller interaction with soil are based on the provisions of soil mechanics. This approach has been tested in the science of forestry production. It is successfully used by modern domestic and foreign researchers. However, with regard to the development and implementation of a mathematical description of interaction of ultra-low pressure wheeled mover (for example, in all-terrain wheeled vehicle) with supporting surfaces, it is necessary to take into account the ratio of the sides of the mover’s contact spot with the soil, since: mover pressure on the ground is defined as the partial load of a single mover and the area contact spots; the distribution of compressive stress over the depth of the soil mass depends on the ratio of the length and width of the contact spot; the bearing capacity characterizing the resistance to shear of the soil layers depends not only on its physical and mechanical properties, but also on the parameters of the contact spot, which is taken into account by special correction factors, the values of which depend on the aspect ratio of the contact spot. Soil rheology is considered to take into account the number of passes of a wheeled all-terrain vehicle along the route and its speed. One of the characteristics of the impact of the mover is exposure time. Value of the length of the contact spot is also used when determining the impact time of the mover on the soil.

Effects of fiber type, particle size, and soak time on water hydration and estimated potential water releasing capacities of roughages fed to horses

2011 ◽  
Vol 31 (5-6) ◽  
pp. 261 ◽  
Author(s):  
A.M. Parsons ◽  
B.D. Nielsen ◽  
H.C. Schott ◽  
R. Geor ◽  
M. Yokoyama ◽  
...  
Keyword(s):  
Particle Size ◽  
Fiber Type ◽  
Type Particle

scholarly journals Prediction Model of Minimum Void Ratio for Various Sizes/Shapes of Sandy Binary Mixture

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Chaojie Shen ◽  
Zhaoyang Xu ◽  
Jie Yin ◽  
Jinfeng Wu
Keyword(s):  
Particle Size ◽  
Binary Mixture ◽  
Particle Shape ◽  
Void Ratio ◽  
Soil Mechanics ◽  
Influence Factors ◽  
Natural Sand ◽  
Undetermined Coefficient ◽  
Shape Characteristics ◽  
Different Origins

The minimum void ratio is a fundamental physical index for evaluating particle properties in soil mechanics, ceramic processing, and concrete mixes. Previous research found that both particle size distribution and particle shape characteristics would affect minimum void ratio, while the current research generally uses a linear model to estimate the minimum void ratio of a binary mixture, ignoring quantitative effect of particle shape on the minimum void ratio. Based on a study of binary mixtures of natural sand from three different origins and iron particles of two different shapes, this paper analyzes the influence factors of the minimum void ratio, and a quadratic nonlinear model is proposed for estimating the minimum void ratio of binary mixture. The model contains only one undetermined coefficient, a, the value of which is correlated to the particle sphericity, particle size, and particle size ratio. A theoretical calculation formula for the coefficient a is proposed to quantitatively analyze the effects of these three factors on the size of the parameters. In the end, the model is used to estimate the minimum void ratios of sand and substitute particles from different producing areas; the average difference between the estimated values and the fitted values is about 2.03%, suggesting that the estimated values of the model fit well with the measured data.

scholarly journals The Research on a Confined Modeling Method of the Effect of Deformable Ground Soil and Crawler Board

2018 ◽  
Vol 237 ◽  
pp. 02011
Author(s):  
LV Wei ◽  
Zhong-xin LI ◽  
LOU Peng
Keyword(s):  
Maximum Stress ◽  
Ground Deformation ◽  
Soil Mechanics ◽  
Soil Surface ◽  
Physical Significance ◽  
Soil Parameters ◽  
Soil Test ◽  
Analysis Model ◽  
Soil Pressure ◽  
Vehicle Mobility

There is a great relationship between the passing capacity of vehicles on the ground deformation road and the properties of confined and shear of ground soil, so it is necessary to establish a model that can reflect the soil pressure of the deformation. Physical significance of classic soil pressure experience parameters model is indeterminate, it was generally obtained by a lot of specific soil test. In this paper a new analysis model was built though introducing the maximum stress value of the crawler board and soil surface on basis of a kind of existing analysis model. This model reveals the relations among the confined characteristics of soil, soil parameters and the geometry of confined crawler board. These soil parameters can be obtained through the conventional soil mechanics test without a large number of specific soil test. Through the contrast experiment and predictions results, this model can effectively predict the sinkage of ground soil under the load, and provide a theory basis for the prediction of vehicle mobility.

Soil Cohesion Development under Different Pore and Size Characteristics

2020 ◽  
Author(s):  
Cagla Temiz ◽  
Fikret Ari ◽  
Selen Deviren Saygin ◽  
Sefika Arslan ◽  
Mehmet Altay Unal ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Soil Properties ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Soil Mass ◽  
General Terms ◽  
Soil Cohesion ◽  
Wide Range ◽  
Fluid Bed

<p>Soil cohesion (Co) is one of the most important physical soil characteristics and it is closely related to the basic soil properties and physical distribution forces (e.g. particle size distribution, pore sizes, shear strength) and so it is mostly determined by experimentally approaches with the help of other soil properties in general terms. Instead of using these assumptions, the fluidized bed approach provides an opportunity for direct measurement of intrinsic soil cohesion. In this study, soil cohesion development for different soil types was investigated with the fluid-bed method by which pressure drop in soil mass measures under increasing water pressures until the cohesion between particles disappears. For this purpose, 20 different soils varying with a wide range of relevant soil physical properties were sampled; such that clay, silt and sand contents varied between 2% and 56%, 1% and 50%, and 1% and 97%, respectively while porosity values were between 0.38 and 0.92. By those textural diversities of the soils, obtained cohesion values changed between 5203 N m<sup>-3</sup> and 212276 N m<sup>-3</sup>. Given results from regression analysis, a significant relationship was found between cohesion values of the soils and their porosity and silt fractions (R<sup>2</sup>: 86.6).These findings confirm that the method has a high potential to reflect differential conditions and show that soil cohesion could be modeled by such basic and easily obtainable parameters as particle size distribution and porosity, as well.<strong> </strong></p><p><strong>Key words</strong>; <strong>Mechanical soil cohesion, particle size distribution, fluidized bed approach, porosity</strong></p>

Ozone and Sunlight Effect on Aging of Carbon Black Vulcanizates

1953 ◽  
Vol 26 (1) ◽  
pp. 127-135
Author(s):  
George E. Popp ◽  
Lynn Harbison
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Carbon Black ◽  
Natural Rubber ◽  
Size Structure ◽  
Synthetic Polymer ◽  
Ozone Exposure ◽  
Polymer Compound ◽  
Type Particle ◽  
Weather Resistance

Abstract Carbon black, regardless of type, particle size, structure, and physical properties imparted, does not affect the rate or degree of checking or cracking in natural-rubber or low-temperature polymer compounds when subjected to weather or ozone exposure. Natural rubber will withstand much longer periods of exposure than the synthetic polymer studied. A pronounced degree of ozone and weather cracking and checking will result if no antioxidant is compounded into the synthetic polymer. An MAF black-synthetic polymer compound may be substantially improved in its resistance to ozone and weather resistance by selection and application of the proper antichecking ingredients.

Study on Load-Bearing Mechanism of Stabilizing Pile-Groups by FEM and its Application

2014 ◽  
Vol 638-640 ◽  
pp. 656-670
Author(s):  
Huan Feng Qiu ◽  
Shao Jun Fu
Keyword(s):  
Computer Code ◽  
Soil Mass ◽  
Design Parameters ◽  
Pile Groups ◽  
Soil Pressure ◽  
Soil Arching ◽  
Fine Grained ◽  
Arching Effect ◽  
Soil Arching Effect ◽  
Pile Diameter

The behaviour of pile-groups subjected to lateral soil pressure is a key consideration in establishing the design parameters of pile-groups. In this paper, one representative section of the Chongqing Jiangdong slope is taken as an example. The existence of an arching zone around pile groups for granular and fine-grained soils is first examined using the finite element computer code CORE-3D. Pile load-displacement curves and the arching effect are considered together to explain how the stresses are transferred from the soil to the piles. The key parameters controlling the soil arching effect are centre-to-centre pile spacing (S), thickness of stable soil mass (H), depth (L) of pile embedment, pile diameter (D) and these were studied extensively. An empirical equation summarising the results is presented and the results have been adopted by the designer in practice.

scholarly journals EDAPHATIC FACTORS AFFECTING SEEDLING PERMANENT EMERGENCE

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 577f-577
Author(s):  
Burton J. Hoyle
Keyword(s):  
Water Management ◽  
Particle Size ◽  
Critical Stress ◽  
Seedling Emergence ◽  
Soil Mass ◽  
Energy Requirements ◽  
Emergence Time ◽  
Factors Affecting ◽  
Fine Soil ◽  
Soil Stress

Soil particle size was found to affect expansion and contraction of soil mass as moisture changed; thus all other seedling emergence stresses changed. Cohesion between soil particles is changed by soil type, content, and particle size, which in turn changes seed energy requirements for survival and emergence. The rates of germinating/emerging; seed/seedlings accelerated or stopped depending on moisture fluctuations and water degradation of aggregates. The same moisture content may be damaging in one soil and not in another. Many seedlings with developed radicals and hypocotyls did not emerge and were found in pockets of fine soil below 0.5mm; or as if their energy had been used up. Stands after emergence frequently varied greatly in vigor and survival by many units. Vigorized seed produced variable results depending on soil stress limitations during emergence. That is, laboratory differences did not always reflect in the field. The least critical stress period was between planting and the emergence of the radical--about 1/3 of the emergence time. Ideal seed beds often produced poor stands when water management and temperature were stressful. Packing density was found a good measure of seed-bed soil quality.

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