Assessment of slope stability in cohesive soils due to a rainfall     

S. Pietruszczak  E. Haghighat 《国际地质力学数值与分析法杂志》2013,37(18):3278-3292

The primary focus in this work is on proposing a methodology for the assessment of stability of natural/engineered slopes in clayey soils subjected to water infiltration. In natural deposits of fine‐grained soils, the presence of water in the vicinity of minerals results in an interparticle bonding. This effect cannot be easily quantified as it involves complex chemical interactions at the micromechanical level. Here, the evolution of strength properties, including the apparent cohesion resulting from initial suction at the irreducible fluid saturation, is described by employing the framework of chemoplasticity. The paper provides first the formulation of the problem; this involves specification of the constitutive relation, development of an implicit return mapping scheme, and the outline of a coupled transient formulation. The framework is then applied to examine the stability of a slope subjected to a prolonged period of intensive rainfall. It is shown that the water infiltration may trigger the loss of stability resulting from the degradation of material properties. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Sediment infiltration traps: their use to monitor salmonid spawning habitat in headwater tributaries of the Cascapédia River,Québec     

Andr E. Zimmermann  Michel Lapointe 《水文研究》2005,19(20):4161-4177

Sediment infiltration can clog salmon nests and reduce egg survival. As a countermeasure, environmental managers often deploy infiltration traps to monitor sediment infiltration. Traps provide a repeatable means of measuring infiltration and enable comparisons to be made between sites. Results from infiltration rates measured with traps have also been used to estimate infilling rates into salmon nests. Application of these data is questionable, as the composition of the bed and the amount of fine sediment within the bed is known to affect infiltration rates. Thus, infiltration rates measured with infiltration traps may differ from the infiltration rates occurring in redd and riffle gravels. To examine how relationships between sediment infiltration rates varied between four watersheds, we continuously monitored suspended sediment transport, shear stress and infiltration rates at four sites over 5 months. We also compared infiltration rates measured with infiltration traps with changes in the hydraulic conductivity and subsurface grain size distribution of adjacent artificially constructed salmon nests and natural riffle gravels. Among the four watersheds, clear differences in sediment infiltration rates were observed. The differences correlated with the subsurface silt content but no strong relationship existed between land‐use or basin physiography/geology. Despite observing an average of 30 kg m⁻² of sediment finer than 2 mm being deposited in the infiltration traps during the study, no change in redd or riffle substrate was observed. If the deposition rates measured with the traps reflect the processes in redds, enough sediment would have been deposited to inhibit egg emergence. However, no reduction in egg survival to the eyed stage was observed. In summary, our results show that infiltration traps with clean gravels can be used to detect intersite differences in sediment transport regimes. Extrapolations of sediment infiltration rates measured with such collectors to estimate infiltration rates in redds or riffles is, however, flawed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Curve‐Number/Green–Ampt mixed procedure for streamflow predictions in ungauged basins: Parameter sensitivity analysis     

S. Grimaldi  A. Petroselli  N. Romano 《水文研究》2013,27(8):1265-1275

A procedure combining the Soil Conservation Service‐Curve Number (SCS‐CN) method and the Green–Ampt (GA) infiltration equation was recently developed to overcome some of the drawbacks of the classic SCS‐CN approach when estimating the volume of surface runoff at a sub‐daily time resolution. The rationale of this mixed procedure, named Curve Number for Green–Ampt (CN4GA), is to use the GA infiltration model to distribute the total volume of the net hyetograph (rainfall excess) provided by the SCS‐CN method over time. The initial abstraction and the total volume of rainfall given by the SCS‐CN method are used to identify the ponding time and to quantify the hydraulic conductivity parameter of the GA equation. In this paper, a sensitivity analysis of the mixed CN4GA parameters is presented with the aim to identify conditions where the mixed procedure can be effectively used within the Prediction in Ungauged Basin perspective. The effects exerted by changes in selected input parameters on the outputs are evaluated using rectangular and triangular synthetic hyetographs as well as 100 maximum annual storms selected from synthetic rainfall time series. When applied to extreme precipitation events, which are characterized by predominant peaks of rainfall, the CN4GA appears to be rather insensitive to the input hydraulic parameters of the soil, which is an interesting feature of the CN4GA approach and makes it an ideal candidate for the rainfall excess estimation at sub‐daily temporal resolution at ungauged sites. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Mosaic desert pavement influences water infiltration and vegetation distribution on fluvial fan surfaces     

Dejin Wang  Wenzhi Zhao  Hong Zhou  Weicheng Luo  Hu Liu 《水文研究》2021,35(9):e14373

Desert pavements (DPs) are critical for maintaining ecological stability and promoting near-surface hydrological cycling in arid regions. However, few studies have focused on eco-hydrological processes of DPs in the ecological systems of fluvial fans. Although DP surfaces appear to be barren and flat, we found that the surfaces are characterized by surface mosaic patterns of desert pavement (mosaic DP) and bare ground (mosaic BG). We investigated the effects of mosaic DP on water infiltration and vegetation distribution at six sites in fluvial fans (one on a hillside and five within the sectors of fans) along a southwest belt transect in northern Linze County, in the central Hexi Corridor (China). We found significant differences in mosaic DP between the hillside and sector sites in terms of pavement thickness and vesicular horizon thickness (Av thickness), particle composition, and bulk density, although significant differences were absent for mass soil water content, gravel coverage, and surface gravel size. The mosaic DP inhibited water infiltration by the pavement layer, where the sorptivity (S), initial infiltration rate (i_int), steady-state infiltration rate (i_sat) and infiltration time (T) averaged 1.19 cm/min^-0.5, 0.64 cm/min, 0.13 cm/min and 12.76 min, respectively. Where the pavement layer was scalped, the S, i_int, and i_sat increased by 0.27 cm/min^-0.5, 0.52 cm/min, and 0.40 cm/min, respectively, and the T reduced by 7.42 min. Water infiltration was mainly controlled by the pavement layer thickness (+), Av thickness (−), surface gravel coverage (−), fine earth (+) and fine gravel (−) in the pavement layer. The DP surfaces only had a sparse covering of shrubs, but an abundance of herbs. Few shrubs were present on the mosaic DP, but a greater number of shrubs and herbs grew on the mosaic BG. It can be concluded that DPs can maintain vegetation stability for different surface mosaic patterns. This study deepens our understanding of the eco-hydrological cycle of DP landscapes in arid regions.  相似文献   

Spatial–temporal variability and hydrologic connectivity of runoff generation areas in a North Alabama pasture—implications for phosphorus transport     

Sumit Sen  Puneet Srivastava  Jacob H. Dane  Kyung H. Yoo  Joey N. Shaw 《水文研究》2010,24(3):342-356

This study delineated spatially and temporally variable runoff generation areas in the Sand Mountain region pasture of North Alabama under natural rainfall conditions, and demonstrated that hydrologic connectivity is important for generating hillslope response when infiltration‐excess (IE) runoff mechanism dominates. Data from six rainfall events (13·7–32·3 mm) on an intensively instrumented pasture hillslope (0·12 ha) were analysed. Analysis of data from surface runoff sensors, tipping bucket rain gauge and HS‐flume demonstrated spatial and temporal variability in runoff generation areas. Results showed that the maximum runoff generation area, which contributed to runoff at the outlet of the hillslope, varied between 67 and 100%. Furthermore, because IE was the main runoff generation mechanism on the hillslope, the data showed that as the rainfall intensity changed during a rainfall event, the runoff generation areas expanded or contracted. During rainfall events with high‐intensity short‐ to medium‐duration, 4–8% of total rainfall was converted to runoff at the outlet. Rainfall events with medium‐ to low‐intensity, medium‐duration were found less likely to generate runoff at the outlet. In situ soil hydraulic conductivity (k) was measured across the hillslope, which confirmed its effect on hydrologic connectivity of runoff generation areas. Combined surface runoff sensor and k‐interpolated data clearly showed that during a rainfall event, lower k areas generate runoff first, and then, depending on rainfall intensity, runoff at the outlet is generated by hydrologically connected areas. It was concluded that in IE‐runoff‐dominated areas, rainfall intensity and k can explain hydrologic response. The study demonstrated that only connected areas of low k values generate surface runoff during high‐intensity rainfall events. Identification of these areas would serve as an important foundation for controlling nonpoint source pollutant transport, especially phosphorus. The best management practices can be developed and implemented to reduce transport of phosphorus from these hydrologically connected areas. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Flood forecasting and infiltration modeling/Prévision de crue et modélisation de l’infiltration     

《水文科学杂志》2013,58(2)

Abstract

Abstract The role of accuracy in the representation of infiltration on the effectiveness of real-time flood forecasting models was investigated. A simple semi-distributed model of conceptual type with adaptive estimate of hydraulic characteristics included in the infiltration component was selected. Infiltration was described by a very accurate approach recently formulated for complex rainfall patterns, or alternatively through a simpler formulation known as an extension of the classical time compression approximation. The results indicated that, for situations involving a significant rainfall variability in space, the inaccuracy in the representation of infiltration cannot be corrected by the adaptive component of the rainfall–runoff model. A preliminary analysis of the role of an approximation of saturated hydraulic conductivity to be used in each homogeneous area of the semi-distributed model used both in non-adaptive version and in real-time is also presented.  相似文献   

运城市地下水咸化趋势预测——准三维数值模拟方法   总被引：2，自引：0，他引：2       下载免费PDF全文

陈崇希  刘建刚 《地球科学》1993,18(1):48-59

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Infiltration-driven dehydration and anatexis in granulite facies metagabbro, Grenville Province, Ontario, Canada   总被引：2，自引：0，他引：2  

D. R. M. PATTISON 《Journal of Metamorphic Geology》1991,9(3):315-332

Dark hornblende + garnet-rich, quartz-absent metagabbro boudins from the Seguin subdomain, Ontario Grenville Province, are transected by anastomosing light-coloured veins rich in orthopyroxene, clinopyroxene, plagioclase and sometimes quartz. The veins vary in texture from fine-grained diffuse veins and patches that overprint the metagabbro, to coarse tonalitic leucosomes with sharp borders. The diffuse veins and patches are suggestive of channellized subsolidus dehydration of the metagabbro, while the tonalitic leucosomes are suggestive of local internally-derived anatexis. All vein types grade smoothly into each other, with the tonalitic leucosomes being the latest.
Relative to the host metagabbro, the veins have higher Si, Na, Ba & Sr, lower Fe, Mg, Ca & Ti, and similar Al. The coarser veins are enriched in K. Plagioclase becomes steadily enriched in Na in the transition from host metagabbro (An₄₇) to the veins (An₃₅), and in the coarsest veins it is antiperthitic. Differences in composition of the other minerals between host metagabbro and vein are minor. Pressure–temperature estimates are scattered, but indicate a minimum temperature during vein formation of 700°C at about 8 kbar.
Mass balance constraints indicate that the veins formed from the metagabbro in an open system. The transecting veins are interpreted to represent pathways of Si + Na + Ba + Sr ± K ± Al-enriched, low a _H2O fluids that metasomatized the host metagabbro to form the anhydrous veins. An initial period of localized solid-state dehydration of the metagabbro, represented by the diffuse veins, was followed by a transition to localized anatexis, represented by the tonalitic leucosomes. The change to anatexis may have been due to the addition of K to the infiltrating fluid. The source and delivery mechanism of the fluids is unknown.  相似文献   

Fluid flow patterns and infiltration isograds in melilite marbles from the Bufa del Diente contact metamorphic aureole, north-east Mexico   总被引：2，自引：0，他引：2  

W. HEINRICH  M. GOTTSCHALK 《Journal of Metamorphic Geology》1994,12(4):345-359

In the inner aureole of the Bufa del Diente alkali syenite (north-east Mexico), thin calcareous argillite bands horizontally embedded in impure marbles acted as contact-metamorphic aquifers for hypersaline brines of magmatic origin. Thick-bedded marbles were largely impervious. From 180 m up to the intrusion contact, argillites were completely decarbonated, resulting in melilite + wollastonite + phlogopite + perovskite-bearing parageneses. In marbles, this assemblage is confined to a narrow 7-12-m-wide infiltration zone adjacent to the contact. Up to this distance, calcite + wollastonite + diopside + alkali feldspar + titanite was stable, indicating that the fluid evolution in these marbles was internally buffered. Brine infiltration from the metaargillite aquifer into the marbles occurred perpendicular to the marble-metaargillite boundaries and was confined to a zone 4-6 cm wide above the boundaries. This is documented by the three reactions Cc + Di = Mel + CO₂, (1) Cc + Kfs + Di + H₂O = Phl + Wo + CO₂, (2) Cc + Ttn = Prv + Wo + CO₂, (3) Melilites (Ak_32-45Gh_13-32Sm_32-40 to Ak_52-72Gh_0-1Sm_28-48) occur as rims around diopsides and become continuously thicker towards the metaargillite beds. Fluid inclusion observations suggest that the infiltrating brine was hypersaline (NaCl + KCl_cq～ 65 wt%) and that the reactions took place at the water-rich side of the H₂O-CO₂-salts immiscibility field at about 600d? C (2, 3) and 660 to 680d? C (1) at P～ 1200 bar and X_co2～ 0.02. Mass balance calculations show that the amount of brine infiltrated from the aquifer into the marble was very low and decreased continuously with increasing distance from the boundary. The maximum width of brine infiltration was about 6 cm. This confirms that brine flow was largely parallel to the aquifer, not perpendicular to it. The CO₂ produced by the decarbonation reactions probably escaped as an immiscible low-density H₂O-CO₂ fluid of X_co2≤ 0.5 into overlying marble via grain-edge flow. The metaargillite-marble boundary acted as a semipermeable membrane 6 cm in thickness keeping back the brine in the aquifer and losing the in-situ produced low-density CO₂-rich fluid.  相似文献   

江西德兴斑岩铜矿床某些元素的扩散和渗滤作用     

Tang Yuanjun 《地球科学》1986,(1)

以江西德兴斑岩铜矿床之细矿脉为研究对象,文章介绍了细矿脉剖面采集及研究的工作方法,着重讨论了自矿脉至围岩元素的空间展布特征。成矿元素Cu、Ag、S和控矿元素Fe、Rb、K都属确定性分布型。对照元素的扩散和渗滤理想模式,得到如下认识:在成矿成晕的地球化学过程中,成矿元素Cu、Ag、S以及Fe以扩散作用为主,控矿元素K和Rb以渗滤作用为主。  相似文献