scholarly journals Laboratory Model Tests on Flow Erosion Failure Mechanism of a Slope Consisting of Anqing Group Clay Gravel Layer

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Kang Huang ◽  
Haipeng Duan ◽  
Yuelin Yi ◽  
Fei Yu ◽  
Shanxiong Chen ◽  
...  
Keyword(s):  
Total Mass ◽  
Rainfall Intensity ◽  
Infiltration Rate ◽  
Steep Slope ◽  
Slope Ratio ◽  
Gravel Content ◽  
Gravel Layer ◽  
Runoff Rate ◽  
Sloping Surface ◽  
The Stability

The Anqing group clay gravel layer is a special geological body composed of gravel and clay. In excavation projects, involving this soil, such a gravel layer, is prone to slope collapse and instability under the influence of rainfall. To clearly understand the failure mechanism and influencing factors of clay gravel slopes, an indoor artificial rainfall erosion model testing was carried out to analyse the effect of various slope ratios, gravel contents, and rainfall intensities. The slope erosion damage form, runoff rate, infiltration rate, scoured material, and slope stability of the clay gravel slope were studied. The test results show that sloping surfaces of the gentle slope were mainly damaged by erosion, and the degree of damage gradually increased from the top to the bottom of the sloping surface; however, the stability of the surface was good. In the case of the sloping surface layer of the steep slope, large-scale landslides occurred, and the stability of the surface was poor. When the gravel content was small, the surface failure was manifested as a gully failure. When the gravel content was large, it was manifested as a “layer-by-layer sliding” failure. The degree of influence of different conditions on the stable runoff rate was as follows: rainfall intensity>slope ratio>gravel content. The degree of influence of the parameters on the stable infiltration rate was as follows: slope ratio>rainfall intensity>gravel content. On gentle slopes, the total mass of the scoured material was inversely proportional to the gravel content and directly proportional to the rainfall intensity; on a steep slope, the total mass of the scoured material increased with an increase in the rainfall intensity and gravel content. Moreover, the slope ratio was the key influencing factor to decide whether there was gravel in the scoured material.

Naturally rainfall-induced changes in runoff-associated nitrogen and phosphorus losses in purple soil area: roles of land disturbance and plot length

2021 ◽  
Author(s):  
Ke Liang ◽  
Binghui He
Keyword(s):  
Rainfall Intensity ◽  
Purple Soil ◽  
Rainfall Events ◽  
Dissolved Phosphorus ◽  
Land Disturbance ◽  
P Concentration ◽  
Long Duration ◽  
Artificial Disturbance ◽  
Runoff Rate ◽  
Sloping Land

<p>Severe soil erosion occurs in southwestern China owing to the large expanses of human disturbance and sloping land. This field monitoring study was conducted during the rainy season to record the rainfall events, runoff, sediment yield, nitrogen, and phosphorous loss in 20-, 40-, and 60-m plots under conditions of artificial disturbance or natural restoration on a 15° slope in the purple soil area of southwestern China. The concentrations and loss amounts of total nitrogen (TN), total dissolved nitrogen (TDN), ammonium-nitrogen (NH4-N) and nitrate-nitrogen (NO<sub>3</sub>-N), total phosphorus (TP), total dissolved phosphorus (TDP) and orthophosphate (PO<sub>4</sub>-P) were comparatively determined. The highest N concentration was observed in long duration and soft rainfall events across all plots. The highest P concentration in artificial disturbed plots was found in long duration and intensive rainfall events while it was recordeds for measured variables were dominantly recorded under the long duration and lowest soft rainfall events in naturally restored plots intensity., while The the highest loss amounts for N and P in different forms for these variablesalmostmostly appeared under high rainfall intensity. Land disturbances differed orthophosphate PO<sub>4</sub>-P concentration in 20--m plot and and loss amounts of of measured variables N and P with different forms across in all plots. Plot lengths differed total dissolved phosphorus TDP concentration in natural restored plot and loss amounts of total dissolved nitrogenTDN and orthophosphate PO<sub>4</sub>-P in artificially disturbed plots. Naturally restoration reduced loss amounts of total nitrogen and total phosphorus by 69.4%62.14-79.05% and 79.28-83.43% TN, 68.8% TDN, 71.2% NH<sub>4</sub>-N, 74.3% NO<sub>3</sub>-N, 81.5% TP, 71.9% TDP and 70.0% PO<sub>4</sub>-P loss amounts comparedrelative to artificial disturbance, respectively. There were significant interrelationships among N and P concentrations in different forms in two land disturbance plots, while nitrate-NO<sub>3</sub>-nitrogenN concentration hadwas significantly negatively negative correlatedion with rainfall intensity and runoff rate in artificialally disturbanceed plots. Rainfall intensity was logarithmically correlated with TN, NO<sub>3</sub>-N concentrations in artificially disturbed plots and with NO<sub>3</sub>-N concentration in naturally restored plots. Runoff rate was logarithmically correlated with TN, TDN and NO<sub>3</sub>-N concentrations in artificially disturbed plots. Our results highlight the effects of land disturbance and plot length on nutrient losses in sloping land.</p>

scholarly journals Transparency and stability of low density stellar plasma related to Boltzmann statistics and to thermal bremsstrahlung

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Y. Ben-Aryeh
Keyword(s):  
Large Volume ◽  
Spherical Symmetry ◽  
Total Mass ◽  
Electron Gas ◽  
Low Density ◽  
Gravitational Forces ◽  
Magnetic Spectrum ◽  
Boltzmann Statistics ◽  
Electro Magnetic ◽  
The Stability

AbstractThe stability of low density stellar plasma is analyzed for a star with a spherical symmetry which is in equilibrium between the gravitational attractive forces and the repulsive pressure forces of an ideal electron gas where the analysis is developed by the use of Boltzmann statistics. Fundamental results are obtained for the radius and total mass of such star and its gravitational forces are large due to the extreme large volume. The absorption and emission of radiation for extremely low density star plasmas is very small over the entire electro-magnetic spectrum.

scholarly journals Study on Variation of Surface Runoff and Soil Moisture Content in the Subgrade of Permeable Pavement Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lijun Hou ◽  
Yuan Wang ◽  
Fengchun Shen ◽  
Ming Lei ◽  
Xiang Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Soil Moisture Content ◽  
Asphalt Pavement ◽  
Infiltration Rate ◽  
Runoff Coefficient ◽  
Flood Peak

The self-designed indoor simulated rainfall device was used to rain on five types of pavement structures with 4 types of rainfall intensity (2.5 mm/min, 3.4 mm/min, 4.6 mm/min, and 5.5 mm/min). The effect of rainfall intensity on the surface runoff, the relation between the subgrade soil moisture content changes, and the influence of initial soil water content on rain infiltration rate are studied. The test results show that the surface runoff coefficient of densely asphalted pavement is greater than 90% in drainage pavements and it has little influence on the reducing and hysteresis of the flood peak. The surface runoff coefficient of large-void asphalt pavement (permeable) is less than 40%. Although the large-void asphalt pavement (permeable) can reduce a small amount of surface runoff, it has no obvious effect on the reduction and hysteresis of the flood peak. In semipermeable pavement, with the increasing of the thickness of base (graded gravel), the surface runoff coefficient decreases at different rainfall intensities, parts of the surface runoff are reduced, and the arrival of flood peaks is delayed. In permeable roads, almost no surface runoff occurred. As time continued, the soil moisture content quickly reached a saturated state and presented a stable infiltration situation under the action of gravity and the gradient of soil water suction. As the initial moisture content increases, the initial infiltration rate decreases and the time to reach a stable infiltration rate becomes shorter. The drier the soil, the greater the initial infiltration rate and the higher the soil moisture content after infiltration stabilization. Permeable roads can greatly alleviate the pressure of urban drainage and reduce the risk of storms and floods.

Settlement and Deformation Laws of High Loess-Filled Embankment Based on Centrifugal Model Test

2011 ◽  
Vol 90-93 ◽  
pp. 222-229
Author(s):  
Wei Bing Zhang ◽  
Lian Tang
Keyword(s):  
Model Test ◽  
Spatial Effect ◽  
Slope Ratio ◽  
Actual Measurement ◽  
Construction Period ◽  
Centrifugal Model Test ◽  
Lateral Extrusion ◽  
Distribution Laws ◽  
The Stability ◽  
Centrifugal Model

In view of the settlement problem of high loess-filled embankments themselves, with the reference of the 30m high embankment at K5 +536 of Lan Lin provincial expressway and by means of the centrifugal model test, the developing process of the settlement for embankment itself with time in different sections of embankment and the distribution laws of the settlement subjected from spatial effect in case of the different terrain conditions are studied. Compared with the actual measurement, the results show that: as far as the settlement of high-filled embankment itself is concerned, the settlement at the central part along the cross-section of embankment is larger than that at shoulder; When the stability of embankment is relatively poor because of the bigger slope ratio or faster speed of construction, the settlement at the shoulder caused by the lateral extrusion from the edge of embankment is larger; The settlement of embankment itself is approximately 0.5% -1% of the height of embankment, about 75% -85% of which occurred during the construction period and the remaining 15% -25% belongs to after construction. Furthermore, the 85% of the settlement belong to after construction will be completed within a year and about two years later the settlement tend to be stable; Owing to the affection of the spatial effect due to the valley terrain conditions, the settlement near the joint sites between the embankment and the gully is larger than that occurred in gentle slope and the central part of embankment. During the time of designing and construction for high-filled embankment, the location where the settlement influenced by the lateral extrusion and spatial effect should be paid attention to, so that, the security and stability of the embankment could be ensured.

scholarly journals Karst bare slope soil erosion and soil quality: a simulation case study

Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 985-995 ◽  
Author(s):  
Q. Dai ◽  
Z. Liu ◽  
H. Shao ◽  
Z. Yang
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Infiltration Rate ◽  
Soil Infiltration ◽  
Seepage Rate ◽  
Rainfall Duration ◽  
Sediment Production ◽  
Correlation Degree ◽  
Slope Runoff

Abstract. The influence on soil erosion by different bedrock bareness ratios, different rainfall intensities, different underground pore fissure degrees and rainfall duration are researched through manual simulation of microrelief characteristics of karst bare slopes and underground karst crack construction in combination with artificial simulation of rainfall experiment. The results show that firstly, when the rainfall intensity is small (30 and 50 mm h−1), no bottom load loss is produced on the surface, and surface runoff, underground runoff and sediment production are increased with the increasing of rainfall intensity. Secondly, surface runoff and sediment production reduced with increased underground pore fissure degree, while underground runoff and sediment production increased. Thirdly, raindrops hit the surface, forming a crust with rainfall duration. The formation of crusts increases surface runoff erosion and reduces soil infiltration rate. This formation also increases surface-runoff-erosion-damaged crust and increased soil seepage rate. Raindrops continued to hit the surface, leading the formation of crust. Soil permeability showed volatility which was from reduction to increases, reduction, and so on. Surface and subsurface runoff were volatile with rainfall duration. Fourthly, when rock bareness ratio is 50 % and rainfall intensities are 30 and 50 mm h−1, runoff is not produced on the surface, and the slope runoff and sediment production present a fluctuating change with increased rock bareness ratio. Fifthly, the correlation degree between the slope runoff and sediment production and all factors are as follows: rainfall intensity-rainfall duration-underground pore fissure degree–bedrock bareness ratio.

Soil Erosion Process in Sloped Shrub Plots under Simulated Rainfall

2011 ◽  
Vol 347-353 ◽  
pp. 2094-2097 ◽  
Author(s):  
Pei Qing Xiao ◽  
Wen Yi Yao ◽  
Chang Gao Wang
Keyword(s):  
Soil Erosion ◽  
Sediment Yield ◽  
Rainfall Intensity ◽  
Infiltration Rate ◽  
Simulated Rainfall ◽  
Slope Gradient ◽  
Erosion Process ◽  
Infiltration Process ◽  
Negative Relation ◽  
Runoff And Sediment Yield

Runoff, sediment yield and infiltration process of shrub plots were studied under rainfall intensities of 45, 87 and 127 mm/h with 20° slope gradient using simulated rainfall experiment. The results showed that cumulative runoff and cumulative sediment yield of shrub plot had an obvious positive correlation with rainfall time. Under rainfall intensity of 45 mm/h, runoff and sediment yield of shrub plot kept a constant level. Under rainfall intensity of 87 mm/h, runoff kept a fluctuant increase, whereas sediment yield basically kept steady. Under rainfall intensity of 127 mm/h, runoff and sediment yield of shrub plot increased evidently due to the formation of erosion pits. Infiltration rate of shrub plot had a negative relation with runoff as well as sediment yield.

Improve the Stability of Rotor Subjected to Fluid Leakage by Optimum Diameters Design

1990 ◽  
Vol 112 (1) ◽  
pp. 59-64 ◽  
Author(s):  
J. H. Wang ◽  
F. M. Shih
Keyword(s):  
Total Mass ◽  
High Performance ◽  
Optimization Technique ◽  
Slight Modification ◽  
Labyrinth Seal ◽  
Rotor System ◽  
Fluid Leakage ◽  
Rotor Bearing ◽  
The Stability

For high performance turbomachinery, the fluid leakage in the shroud of the blades and the labyrinth seal may cause instability and limit the output rating. In this work, an optimization technique has been used to find the optimum diameters of shaft elements so that the optimized rotor can sustain maximum fluid leakage excitation. The results show that, even without the increase of total mass of the rotor system, the threshold performance of rotor-bearing systems can be significantly improved by slight modification of the shaft diameters.

scholarly journals Discussion of Observations of the Flow of Matter Within Binary Systems

1973 ◽  
Vol 51 ◽  
pp. 1-21
Author(s):  
Alan H. Batten
Keyword(s):  
Hot Spots ◽  
Total Mass ◽  
Binary Systems ◽  
Empirical Relation ◽  
Circumstellar Matter ◽  
Theoretical Treatment ◽  
Flare Activity ◽  
The Stability ◽  
Limiting Values ◽  
Very High

Observational determinations of density, dimensions, temperatures, and velocities of circumstellar features are surveyed and discussed, with a view to establishing limiting values that could be useful in any theoretical treatment of circumstellar structure. Densities of the order of 1013 particles cm-3 are found for streams and disks, although there is evidence for regions of much lower density in many systems, and some systems may have much denser circumstellar matter.Dimensions of disks seem to be remarkably constant (fractional radius ∼ 0.3) in a wide variety of systems. The total mass of circumstellar matter is always a small fraction of the mass of the system. Temperatures are usually similar to the temperatures of the stars in the system, although hot spots certainly exist in some systems, and ‘flare’ activity is evidence of localized very high temperatures. On the other hand, some systems may contain solid circumstellar matter. Observed velocities are usually several hundred km s-1. The empirical relation between the velocity of rotation of disks and the orbital period is described. Finally, the stability of these features is briefly discussed.

scholarly journals Is this diagramme an argument for binary orbital evolution due to mass-loss?

1981 ◽  
Vol 59 ◽  
pp. 507-513 ◽  
Author(s):  
J. Dommanget
Keyword(s):  
Mass Loss ◽  
Total Mass ◽  
Orbital Evolution ◽  
Spectroscopic Binaries ◽  
The Stability

AbstractIn 1963, a diagramme has been established by the author, for visual and spectroscopic binaries, showing the existence of a real correlation between total mass and eccentricity.The consideration of an up-dated material leads to-day to an identical diagramme confirming the reality and the stability of the mentioned correlation.This diagramme is discussed with the assumption of a substantial secular mass-loss of the components of the considered binaries.

Toward a framework for runoff and soil loss prediction using GUEST technology

Soil Research ◽  
1997 ◽  
Vol 35 (5) ◽  
pp. 1191 ◽  
Author(s):  
B. Yu ◽  
C. W. Rose ◽  
C. A. A. Ciesiolka ◽  
K. J. Coughlan ◽  
B. Fentie
Keyword(s):  
Soil Loss ◽  
Field Data ◽  
Rainfall Intensity ◽  
Rainfall Amount ◽  
Balance Model ◽  
Erosion Processes ◽  
Total Runoff ◽  
Physically Based ◽  
Loss Prediction ◽  
Runoff Rate

In recent years, a number of physically based models have been developed for soil loss predictions. GUEST is one such model based on fundamental physical principles and the current understanding of water erosion processes. GUEST is mainly used to determine a soil erodibility parameter. To apply the model in a predictive mode, the model is simplified in a physically meaningful manner for flow-driven erosion processes, and 2 essential hydrologic variables are identified, namely total runoff amount and an effective runoff rate. These variables are required to determine soil loss for individual runoff events. A simple water balance model was developed and used to predict runoff amount from rainfall amount. The efficiency of this runoff amount model in prediction was over 90% using field data. A 1-parameter regression model (r2 ~ 0·9) for the effective runoff rate was also established which uses peak rainfall intensity in addition to rainfall and runoff amounts. The prediction of peak rainfall intensity for a given rainfall amount and storm type was also sought. The field data were from Goomboorian, near Gympie, in south-east Queensland and these data were used to test and validate both models. Results overall are satisfactory and the approach adopted is promising. A framework for soil loss prediction is established within which individual parts can be further refined and improved.

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