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Soil is considered as a three-phase medium consisting of solid particles, water and air. Its behavior is very difficult to predict, especially under high rate blast loading. In this study, a new three-phase soil model for shock loading is employed to facilitate a full simulation of explosion and the subsequent stress wave propagation in soils. Upon validating the model, extended numerical calculations are carried out and the results are analyzed to demonstrate the change of characteristic parameters of the soils, the inherent distribution of the pressure on individual phases and hence the deformation mechanisms of the soils under blasting loading. Two primary deformation mechanisms exist, one is the deformation of the soil skeleton formed by the solid particles; the other is the deformation of all individual soil phases. It is found that the response of soil near the charge is dominated by the second mechanism while the first mechanism dominates in areas beyond a certain scaled range. The location of the transition zone depends primarily on the initial state of the soil. The results are useful for establishing rational and practical soil models for engineering applications concerning blasting. 相似文献
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Tongxin ZHU 《国际泥沙研究》2002,17(4)
1 INTRODUCTION Soil crusting, or soil sealing, is one of the common phenomena in agricultural lands or semi-arid and arid soils. Due to the breakdown of soil aggregates by raindrops, soil surface develops a very thin, often less than a few millimeters, dense layer. Many studies indicated that such a thin layer significantly reduces infiltration capacity and increases surface runoff (i.e. McIntyre, 1958; Edward and Larson, 1969; Agassi et al., 1985; Bradford et al., 1986; Romkens et al.,… 相似文献
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M.J.M.Rmkens 《国际泥沙研究》2011,(3):385-392
Improved knowledge of the effects of grass and shrub cover in overland flow can provide valuable information for soil and water conservation programs.Laboratory simulated rainfall studies were conducted to determine effects of grass and shrub on runoff and soil loss and to ascertain the relationship between the rate of soil loss and the unit stream power of runoff for a 20°slope subjected to rainfall intensities of 45,87,and 127 mm/h.The results indicated that the average runoff rates ranged from 4.2 to 73.1 mm/h for grass plots and from 9.3 to 58.2 mm/h for shrub plots.Runoff rates from shrub plots were less than those from grass plots for all but the 45 mm/h rainfall intensity regime. Average soil loss rates varied from 5.7 to 120.3 g/min.m~2 for grass plots and from 5.6 to 84.4 g/min.m~2 for shrub plots.Soil loss rates from shrub plots were generally lower than those from grass plots.Runoff and soil loss were strongly influenced by soil surface conditions due to the formation of erosion pits and rills.The rate of soil loss increased linearly with the unit stream power of runoff on both grass and shrub plots.Critical unit stream power values were 0.0127 m/s for grass plots and 0.0169 m/s for shrub plots.Shrub plots showed a greater stability to resist soil detachment and transport by surface flow than grass plots. 相似文献
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S. H. Luk 《地球表面变化过程与地形》1979,4(3):241-255
This paper describes laboratory testing of 148 samples collected from Southern Alberta for erosion by wash and splash. Rainfall intensity was held constant during these tests. Soil aggregation was the most significant variable explaining soil loss. The significance of other soil properties, such as organic carbon and clay content is variable, depending on the interrelationships among aggregate stability, organic content, and clay content of particular soils. Variations in erodibility of the major soils examined are explained by the resistance of aggregates to compaction and dispersion. Splash detachment and wash transport are the dominant erosion mechanisms in inter-rill areas. 相似文献
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Soil CO2 efflux in forest and grassland over 5 years from 2005 to 2009 in a semiarid mountain area of the Loess plateau, China, was measured. The aim was to compare the soil respiration and its annual and inter‐annual responses to the changes in soil temperature and soil water content between the two vegetation types for observing soil quality evolution. The differences among the five study years were the annual precipitation (320.1, 370.5, 508.8, 341.6, and 567.4 mm in 2005–2009, respectively) and annual distribution. The results showed that the seasonal change of soil respiration in both vegetation types was similar and controlled by soil temperature and soil water content. The mean soil respiration across 5 years in the forest (3.78 ± 2.68 µmol CO2 m?2 s?1) was less than that in the grassland (4.04 ± 3.06 µmol CO2 m?2 s?1), and the difference was significant. The drought soil in summer depressed soil respiration substantially. The Q10 value across 5‐year measurements was 2.89 and 2.94 for forest and grassland. When soil water content was between wilting point (WP) and field capacity (FC), the Q10 in both types increased with increasing soil water content, and when soil water content dropped to below WP, soil respiration and the Q10 decreased substantially. Although an exponential model was well fitted to predict the annual mean soil respiration for each single year data, it overestimated and underestimated soil respiration, respectively, in drought conditions and after rain for short periods of time during the year. The two‐variable models including temperature and water content variables could be well used to predict soil respiration for both types in all weather conditions. The models proposed are useful for understanding and predicting potential changes in the eastern part of Loess plateau in response to climate change. 相似文献
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Located in Liaoning Province, one of the traditional heavy industrial areas in China, Dahuofang Reservoir provides drinking water for nearly 30 000 000 citizens, as well as industrial and agricultural water for dozens of several cities and rural areas. The distribution of hazardous heavy metals is described in several types of soil, crops, and in different industrial or mining areas and main sewage irrigation areas. Five possible reasons that may cause the pollution are analyzed and listed. Also we provide some pragmatic suggestions for the remediation of heavy metals in contaminated soils. 相似文献
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In this paper the researches made in 1981-1990 have identified that the annual soil loss in the Three Gorges region is 157 million t. and the annual incoming sediment load of the Three Gorges reservoir is 40 million t. Soil erosion increases with the destruction of vegetative cover and its subsequent evolution. The annual amounts of sediment erosion for forest land, shrub land, grassland and farmland make up respectively 6.19%, 10.76%, 23.05% and 60% of the total erosion of the Three Gorges region; the quantities of incoming sediment load to the Yangtze River from the above four types of land account for 5.95%, 12.42%, 35.46% and 46.1 % of the total amount of sediment transported to the reservoir. The farmland of offers the main source of sediment. Gravitational erosion produces more bed loads, which will present serious threat to the Three Gorges Project if entering the reservoir. Resettlement of people to the upper parts of the mountainous areas for agricultural production will increase the sediment yield of the Three Gorges region by 10-20 million t and increase the incoming sediment of the Yangtze River by 50-60 million t. Consequently, it is necessary to make a realistic assessment of the soil erosion in the Three Gorges region. 相似文献
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In the exploration of the hidden Haihe fault, radon and mercury in soil gas were measured by using FG-3017 radon detector and XG-4 mercury analyzer. In this paper, based on the measurement results of 12 fault gas profiles, and integrating with the exploration results of artificial seismic prospecting, the relationship between anomalous site of fault gas and fault location is analyzed. Using the relationship between anomalous strength of fault gas and fault activity, the activity of Haihe fault is studied, thus the location and activity segmentation of the Haihe fault in Tianjin region are presented. This study shows that the method of fault gas detection can not only identify the preliminary location of fault, but also make preliminary segmentation of fault activity. The fault detected by the method of fault gas measurement is shown as a band. Through contrasting with exploration results of artificial seismic prospecting and analyzing, we find that the fault is located inside the band. According to the measurements of soil gas radon, the Haihe fault can be divided into east and west segments and the activity of the east segment of Haihe fault is stronger than that of the west segment. This is only a relative result, and it is difficult to judge whether the fault is active or not with this result. 相似文献
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Thermal stability of soil organic carbon subjected to water erosion as a function of edaphic factors
Zhongwu Li Linhui Xiao Chuxiong Deng Zaijian Yuan Chen Liang Qian Xiong Zeting Li Xiaodong Nie 《国际泥沙研究》2022,37(1):26-36
The stability of soil organic carbon （SOC）,as it relates to resistance to decomposition,is important for greenhouse gas emission and climate change.However,the SOC stabilization and its related influencing factors subjected to water erosion remain uncertain.The objective of the current study was to determine the SOC stability under long-term water erosion and to investigate the link between SOC stability and edaphic factors.Soil samples from eroded,depositional,and control sites in a closed wate... 相似文献
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Su-Chin CHEN Seasir CHIEN Cheng-Daw HSIEH Professor Department of Soil Water Conservation National Chung-Hsing University Taichung Taiwan China Engineer Water Way Section Hand County Government Taiwan China Doctoral Student Ins 《国际泥沙研究》2001,16(1)
1 INTRODUCTIONSoil erosion of land surface caused by over development has become more and more serious.Environmental damage resulted from accelerated soil erosion has attracted much attention especi ally overthe past 20 years. Soil erosion stUdies have focused primarily on soil characteristics and climaticvariations. Great achievements have been made in understanding the mechanism of soil erosion, whichallows the develoPment of evaluation models for all types of soil erosion problems. Th… 相似文献
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Four techniques for soil erosion assessment were compared over two consecutive seasons for bare-fallow plots and a maize-cowpea sequence in 1985 at IITA, Ibadan, Nigeria. The techniques used were: tracer (aluminium paint), nails (16 and 25), the rill method, and the Universal Soil Loss Equation (USLE). Soil loss estimated by these techniques was compared with that determined using the runoff plot technique. There was significantly more soil loss (P < 0·01) in bare-fallow than in plots under maize (Zea mays) or cowpea (Vigna unguiculata). In the first season, soil loss from plots sown to maize was 40·2 Mg ha?1 compared with 153·3 Mg ha?1 from bare-fallow plots. In the second season, bare-fallow plots lost 87·5 Mg ha?1 against 39·4 Mg ha?1 lost from plots growing cowpea. The techniques used for assessing erosion had no influence on the magnitude of soil erosion and did not interfere with the processes of erosion. There was no significant difference (P < 0·05) between soil erosion determined by the nails and the runoff plot technique. Soil loss determined on six plots (three under maize, three bare-fallow) by the rill technique, at the end of the season, was significantly lower (P < 0·05) than that determined by the runoff plot technique. The soil loss estimated by the rill method was 143·2, 108·8 and 121·9 Mg ha?1 for 11, 11, and 8 per cent slopes respectively, in comparison with 201·5, 162·0, and 166·4 Mg ha?1 measured by the runoff plot method. Soil loss measured on three bare-fallow plots on 10 different dates by the rill technique was also significantly lower (P < 0·01) than that measured by the runoff plot. In the first season the USLE significantly underestimated soil loss. On 11, 11, and 8 per cent slopes, respectively, soil loss determined by the USLE was 77, 92, and 63 per cent of that measured by the runoff plot. However, in the second season there was no significant difference between soil loss determined by the USLE and that determined by the conventional runoff plot technique. 相似文献
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Richard A. Shakesby 《地球表面变化过程与地形》1993,18(9):823-827
The soil erosion bridge is a simple, robust, cheap, lightweight device comprising a bar which, when mounted on two stakes, provides a stable datum for micro-profiling the soil surface beneath. Its main advantage over similar devices is the unique combination of mounting clamps, which allow for variation in the distance and angle with respect to the vertical of the mounting stakes without loss of accuracy. The design, installation and measurement procedures are described. Applications and limitations are discussed. 相似文献
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J. A. A. Jones 《地球表面变化过程与地形》1987,12(3):229-248
Natural piping doubles the dynamic contributing area on the upper Maesnant stream in mid-Wales, mainly through linking points well beyond the riparian zones of seepage to the stream. Both discharge and sediment transport rates in the major pipes are closely related to the size of shallow surface microtopographic hollows in which they lie, and which themselves are largely created by piping erosion. However, pipe dischrges are frequently generated by contributing areas larger than these surface depressions and some pipes run counter to the surface topography. The redistribution and acceleration of hillslope drainage processes by piping has implications for theories of hillslope development, especially through plan-form modifications, and also for channel discharge and erosion. 相似文献
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Soil air permeability plays a decisive role in the effectiveness of soil vapour extraction (SVE) for the removal of volatile organic contaminants (VOCs) from soil. The objective of this work is to study the change of the soil air permeability during continuous venting and removal of contaminant from a polluted soil. SVE pilot experiments were conducted to investigate the interaction of soil air permeability with total liquids saturation. Oppositely to previous studies, air permeability was measured by fitting pressure data measured in a 3D laboratory venting pilot to an analytical airflow solution. The experimental correlation was compared with two different correlations published previously. A difference was observed between measured and calculated air relative air permeabilities especially for low water saturation degrees. The importance of the correct estimate of relative permeability was then illustrated by comparing vacuums and streamlines calculated using measured permeability and permeability values estimated with the two correlations tested here. Results show that an inappropriate assessment of relative permeability may engender significant errors in designing an SVE system. The second part of this work reports on the influence of air permeability change on the prediction capability of an SVE mathematical model. A significant difference between simulated breakthrough curves, estimated using firstly the relationship established experimentally and secondly the two other correlations, was observed. These results lead us to say that inadequate characterization of the air permeability change may generate significant errors in removal rate and closure time estimates. 相似文献