Numerical Simulation on Damage Effect of Explosion in Multilayer Mediums and Dimensional Analysis

A highly compacted soil layer was detected in an amaranth field in Tulyehualco, Mexico. The purpose of the present work was to analyze the effect of soil compaction on the crop of amaranth. Two plots with superficial (S) (10-15 cm) and intermediate (I) (20-25 cm) levels of compaction were compared. Several crop physiology parameters were studied and soil resistance was measured with a digital penetrometer. The cone Index values of both compacted soil layers were > 3 MPa. Amaranth plants from the S plot had 46% smaller leaf area (p<0.01) and were 12% shorter (p<0.01) than those from the I plot. The grain yield was significantly higher in plants from I compared to plants from S (68 vs 38 g/plant, p< 0.03). Concerning the root growth, the main roots of plants from S were 34% shorter than those from I (p<0.01). The adventitious roots emerging from the stem base were very prolific in both plots (non statistical differences were appreciated). Adventitious roots were 4-4.8 times longer than main of plants from either plot. In summary, our results show that the depth of compacted soil layer has a direct effect on the amaranth crop. Superficial soil compaction rendered short plants with lower grain yield whereas intermediate compaction resulted in taller plants with higher grain yield.

Com o objetivo de avaliar a capacidade de crescimento de raízes em camadas de solo compactadas, quatro espécies de plantas de cobertura (amaranto, milheto ADR 500, capim pé-de-galinha e kenaf) foram cultivadas em anéis de PVC, com níveis de compactação em subsuperfície (densidade do solo: 1,18; 1,34; 1,51 e 1,60 Mg m-3), sendo o experimento conduzido em casa de vegetação, utilizando-se de um Latossolo Vermelho distroférrico. A camada compactada em subsuperfície foi restritiva ao crescimento de raízes das espécies estudadas, ocasionando a concentração de raízes na camada superficial. O milheto ADR 500 e o amaranto foram as espécies que se destacaram na produção de massa seca da parte aérea e conseguiram desenvolver-se nas camadas compactadas e abaixo delas. O milheto ADR500 apresentou maior densidade de comprimento radicular em todas as camadas. O capim pé-de-galinha e o amaranto tiveram comportamento semelhante quanto à densidade de comprimento radicular. O capim pé-de-galinha e o kenaf apresentaram menor massa seca de raízes em relação às demais espécies. O kenaf apresentou menores valores de massa seca da parte aérea, mas não foi afetado pela presença de camadas compactadas.

Seven ripping treatments designed to improve soil physical conditions for revegetation were compared on a test pad simulating an earthen cover for a waste disposal cell. The field test was part of study of methods to convert compacted-soil waste covers into evapotranspiration covers. The test pad consisted of a compacted layer of fine-textured soil simulating a barrier protection layer overlain by a gravelly sand bedding layer and a cobble armor layer. Treatments included combinations of soil-ripping implements (conventional shank [CS], wing-tipped shank [WTS], and parabolic oscillating shank with wings [POS]), ripping depths, and number of passes. Dimensions, dry density, moisture content, and particle size distribution of disturbance zones were determined in two trenches excavated across rip rows. The goal was to create a root-zone dry density between 1.2 and 1.6 Mg m and a seedbed soil texture ranging from clay loam to sandy loam with low rock content. All treatments created V-shaped disturbance zones as measured on trench faces. Disturbance zone size was most influenced by ripping depth. Winged implements created larger disturbance zones. All treatments lifted fines into the bedding layer, moved gravel and cobble down into the fine-textured protection layer, and thereby disrupted the capillary barrier at the interface. Changes in dry density within disturbance zones were comparable for the CS and WTS treatments but were highly variable among POS treatments. Water content increased in the bedding layer and decreased in the protection layer after ripping. The POS at 1.2-m depth and two passes created the largest zone with a low dry density (1.24 Mg m) and the most favorable seedbed soil texture (gravely silt loam). However, ripping also created large soil aggregates and voids in the protection layer that may produce preferential flow paths and reduce water storage capacity.

&lt;div class="htmlview paragraph"&gt;An antipersonnel landmine neutralizing mechanism, called the Mine Hammer, was designed with a prototype developed by the Agriculture and Bioresource Engineering Department, University of Saskatchewan and Defence Research and Development Canada -- Suffield. The Mine Hammer technology combined flail mechanisms and agriculture tillage interaction mechanics. The prototype was retrofitted to be powered by a 78.4 kW tractor and was field evaluated in August 2002. The test plots represented gravel road, prairie clay soil with stubble and full stand of Kochia weed for vegetation and simulated tree stump terrains. Dummy or mechanical replicas of antipersonnel landmines were placed at 0, 25, 50, 100 and 200mm depths. The Mine Hammer triggered and/or fragmented the replica landmines. Its mechanical neutralization effectiveness over the five test plots was 97%. The Mine Hammer produced a two layer overburden consisting of a loose till above a dense, compact soil layer. Non-neutralized mine replicas were buried within the compact layer and were not triggered when subjected to loads from human footsteps, jumping and stomping.&lt;/div&gt;

The sweet potato is very important crop in the South-West warm region of Japan. Land for sweet potato should be plowed 20 to 25cm deep. If it was operated for deep tillage, a potential pollution hazard was increasing. Our objective in this study was to solve this problem and to establish the technique reducing NO3-N pollution.We have attempted to decrease water infiltiration by tillage methods.We proposed some kinds of tillage systems. New methods of tillage systems included hammering the surface of ridge, the combined treatment (compacted soil layer and hammering soil surface) and conventionally cultivated plot. The method of hammering the surface of ridge tended to show suitable soil water storages than other two treatments.This newly developed tillage system was found to be more effective in controling infiltration in sweet potato production during growing season, especially as rainy season.It was obvious that NO3-N in conventional plot had significantly greater concentration near the soil layer (60cm) in comparison with hammering plot. This might suggest that NO3-N did not move and stayed in treatment plots. It was found that treatment by hammering the surface of ridge was lower infiltration from surface to subsoil than conventional plot. In conclusion, it was found that the new methods of tillage system contributed to reduce Nitrate-Nitrogen leaching.

The Qinghai–Tibet Plateau, known as the “Asian Water Tower”, has a thin soil layer with a thick gravel layer underneath. Its unique geological structure, combined with widespread snow and frozen soil in this area, profoundly affect the water circulation processes of the entire region. To thoroughly study the water cycle mechanism of the Qinghai–Tibet Plateau, this study considered the geological and climatic characteristics of this area and selected the Niyang River Basin as the study area. The Water and Energy transfer Processes in the Qinghai–Tibet Plateau (WEP-QTP) model was constructed based on the original Water and Energy transfer Processes in Cold Regions (WEP-COR) model. This model divides the single soil structure into two types of media: the soil layer and gravel layer. In the non-freeze–thaw period, two infiltration models based on the dualistic soil–gravel structure were developed based on the Richards equation in non-heavy rain periods and the multi-layer Green–Ampt model in heavy rain periods. During the freeze–thaw period, a hydrothermal coupling model based on the continuum of the snow–soil–gravel layer was constructed. This distributed hydrological model can dynamically simulate the changes in frozen soil and flow processes in this area. The addition of the gravel layer corrected the original model’s overestimation of the moisture content of the soil layer below the surface soil and reduced the moisture content relative error (RE) from 33.74 % to −12.11 %. The addition of the snow layer not only reduces the temperature fluctuation of the surface soil, but also works with the gravel layers to revise the original model’s overestimation of the freeze–thaw speed of the frozen soil. The temperature RE was reduced from −3.60 % to 0.08 %. In the non-freeze–thaw period, the dualistic soil–gravel structure improved the regulation effect of groundwater on flow, stabilizing the flow process. The maximum RE at the flow peak and valley decreased by 88.2 % and 21.3 %, respectively. In the freeze–thaw period, by considering the effect of the snow–soil–gravel layer continuum, the change in the frozen soil depth of WEP-QTP lags behind that of WEP-COR by approximately one month. There was more time for the river groundwater recharge, which better shows the “tailing” process after October. The flow simulated by the WEP-QTP model was more accurate and closer to the actual measurements, with Nash > 0.75 and |RE| < 10 %. The improved model reflects the effects of the Qinghai-Tibet Plateau special environment on the hydrothermal transport and water cycle process and is suitable for hydrological simulation of the Qinghai-Tibet Plateau.

Nitrogen fertilization of row crops in humid regions can result in leaching of NO3, which represents an inefficient use of resources and may result in environmental degradation. A localized compaction and doming (LCD) fertilizer injector was developed to alter the physical properties of soil surrounding knife‐injected N. Injection by LCD includes smearing macropores below the injection slot, formation of a localized compacted soil layer over the injected N, and formation of a surface dome to cover the compacted soil layer and the fertilizer band. The LCD injector was tested, along with a conventional knife injector (without a covering disk), to evaluate its effect on leaching by determining NO3 and Br tracer redistribution after NO3 fertilizer injection. Chemical distributions were determined by intensive soil sampling to 0.8 m below the soil surface. In a second experiment, corn (Zea mays L.) yield response to both N injectors was evaluated. Four fertilization rates (67, 112, 157, and 202 kg N ha−1 of UAN [urea‐ammonium nitrate]) were used to define yield response. During seasons when rainfall was below average, neither NO3 redistribution nor crop yield showed a response to fertilizer injection technique. During a growing season with above‐average rainfall, 26 kg ha−1 more NO3 and 25 kg ha−1 more Br remained in the top 0.8 m of soil when LCD‐injected. LCD injection increased crop yield approximately 0.48 Mg ha−1 over injection by the conventional knife method during an above‐average rainfall season, indicating that one‐fifth of the conventional knife‐applied N was lost prior to crop uptake during the wet year. These findings suggest that the LCD injector may be effective at reducing leaching losses during growing seasons when rainfall is abundant.

This paper addresses the interpretation of loading tests bearing on a layered system formed by a compacted soil, coal bottom-ash and carbide lime top-layer overlying a compressible residual soil stratum. Load–settlement behaviour is observed from tests carried out using circular steel plates ranging from 0.30 to 0.60 m diameter on the top of a 0.15–0.60 m thick artificially cemented layer. Field data demonstrate the effectiveness of compacted soil–ash–lime layers in increasing bearing capacity and reducing foundation settlements where shallow foundations are used on weak residual soils. The paper also stresses the need to express test results in terms of dimensionless variables in plots of normalised applied pressure against settlement-to-diameter ratio. The efficiency of existing analytical solutions for layered cohesive-frictional soils in determining the bearing capacity of footings on processed cemented soil overlying a weakly bonded residual soil with high void ratio is evaluated.

Tensile properties of geomaterials often play an important role in many geotechnical engineering problems. Compacted soil layers in dams, clay liners in landfills, reinforced earth-retaining wall systems, cement stabilized crushed rocks in pavements, etc. are constantly checked for tensile cracking. This type of cracking happens when the developed tensile stress exceeds the tensile strength of the material. Usually, the tensile strength of natural soil is assumed to be negligible. However, it is proven that cement treated soils possess some amount of tensile strength. The determination of tensile strength of cement treated clay, using a newly developed tensile testing apparatus, is focussed in this study. The existence of an optimum cement content for tensile strength is also discussed.

Catastrophic loss of soils and slope sediments by landslides causes destruction of mountainous environment and outflow of population from affected areas. However, the role of landslides in mountainous regions goes beyond direct destructive activity. The sliding mass expose surfaces for weathering and accumulate loose mineral material, the vital resource for mountain biota and population thus starting new cycles in ecosystems development, forming new habitats for biota and, in some cases, new lands for farming. A chronological sequence of landslides and their adaptation for human needs was studied in Adjara province, the South Caucasus mountainous region, Georgia. As a rule, in 15 years, a thin and compacted soil layer is formed on low and mound surface of a landslide. In 30 years, people start recultivation of the landslide area. After 40–60 years, the landslide area is used as a hayfield. It usually takes 100 years to transform the area into a fully cultivated landscape typical of Mountainous Adjara.

Piled raft is commonly used as foundation for high rise buildings. The design concept of piled raft foundation is to minimize the number of piles, and to utilize the entire bearing capacity. High axial stresses are therefore, concentrated at the region of connection between the piles and raft. Recently, an alternative technique is proposed to disconnect the piles from the raft in a so called unconnected piled raft (UCPR) foundation, in which a compacted soil layer (cushion) beneath the raft, is usually introduced. The piles of the new system are considered as reinforcement members for the subsoil rather than as structural members. In the current study, the behavior of unconnected piled rafts systems has been studied numerically by means of 3D Finite Element analysis via ABAQUS software. The numerical analysis was carried out to investigate the effect of thickness and stiffness of the cushion, pile length, stiffness of foundation soil, and stiffness of bearing soil on the performance of the unconnected piled raft. The results indicate that when unconnected piles are used, the axial stress along the pile is significantly reduced e.g. the axial stress at head of unconnected pile is decreased by 37.8% compared with that related to connected pile. It is also found that the stiffness and thickness of the cushion, and stiffness of foundation soil have considerable role on reduction the settlement.

Parameterized FEM models of multi-layer target are established. Base on the models, the process of long-rod projectile penetrating multi-layer target with two different angles of incidence are carried out by means of FEM analysis program LS-DYNA and the influences of the incident angle and multilayer mediums are studied. The results show that when vertical penetrating the multi-layer target in vicinity of the free surface the projectile underwent large deflexion and eventually escaped from the rock layer and when oblique penetrating the target the projectile penetrated claypan layer, rock layer, grit layer and concrete layer in turn. Different mediums brought different influences on penetration effects. The models and results could provide reference for projectile design and efficiency evaluation.

Cross-laminated timber (CLT) slabs in residential buildings need additional weight, e.g., in the form of screeds or gravel layers, to fulfill the criterion for the highest impact-sound class. The additional mass is, however, not exploited for the load bearing behavior, but adds additional weight and leads to an increased height of the floor construction. In this study, such a CLT floor construction with a construction height of 380 mm is compared with a composite slab consisting of a CLT plate with a concrete layer on top with a floor construction height of 330 mm. The timber concrete composite (TCC) slab has a different creep behavior than the CLT slab. Thus, the development of the time-dependent deflections over the service life are of interest. A straightforward hybrid approach is developed, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behavior. The introduced approach allows to investigate load redistribution between the layers of the composite structure and the evolution of the deflection of the slab during the service life. The investigated slab types show a similar deflection after 50 years, while the development of the deflections over time are different. The CLT slab has a smaller overall stiffness at the beginning but a smaller decrease in stiffness over time than the investigated TCC slab.

Dimensional analysis (DA) is a well-developed, widely-employed methodology in the physical and engineering sciences. The application of dimensional analysis in statistics leads to three advantages: (1) the reduction of the number of potential causal factors that we need to consider, (2) the analytical insights into the relations among variables that it generates, and (3) the scalability of results. The formalization of the dimensional-analysis method in statistical design and analysis gives a clear view of its generality and overlooked significance. In this paper, we first provide general procedures for dimensional analysis prior to statistical design and analysis. We illustrate the use of dimensional analysis with three practical examples. In the first example, we demonstrate the basic dimensional-analysis process in connection with a study of factors that affect vehicle stopping distance. The second example integrates dimensional analysis into the regression analysis of the pine tree data. In our third example, we show how dimensional analysis can be used to develop a superior experimental design for the well-known paper helicopter experiment. In the regression example and in the paper helicopter experiment, we compare results obtained via the dimensional-analysis approach to those obtained via conventional approaches. From those, we demonstrate the general properties of dimensional analysis from a statistical perspective and recommend its usage based on its favorable performance.

Compacted soil mixed with bentonite having a low hydraulic conductivity of less than 10-6 cm/s is commonly used as barrier layer in waste landfill in Japan. But it is afraid that the bentonite mixed soil may have cracks when the base ground experiences a local subsidence. The authors conducted trap door tests of bentonite mixed soil under a surcharge pressure of 107.8kN/m2. The sizes of the compacted soil layer mixed with 10 % bentonite are 800 mm in length, 200 mm in width and 100 or 200 mm in thickness. The width of trap door was changed as 30, 40 and 50 cm. The rate of lowering the door was 1.0 mm/day. It was found that bentonite mixed soil had a crack in the middle height of soil layer when the trap door subsided between 12 and 13 mm. And then the crack reached at top and bottom surfaces when the door was lowered between 13 and 27 mm. Therefore the shear crack is predominant than bending crack. In the study the image analysis for the tests with a lowering rate of 0.5 mm/min was also conducted by recording the deformation on the video. The amount of calculated shear strain at the cracked position was lager than 20%.