Laboratory Study on the Hydraulic Conductivity and Pore Pressure of Sand-Silt Mixtures     

Mostefa Belkhatir  Ahmed Arab  Noureddine Della  Tom Schanz 《Marine Georesources & Geotechnology》2013,31(2):106-122

The hydraulic conductivity plays a major role on the excess pore pressure generation during monotonic and cyclic loading of granular soils with fines. This paper aims to determine how much the hydraulic conductivity and pore pressure response of the sand-silt mixtures are affected by the percentage of fines and void ratio of the soil. The results of flexible wall permeameter and undrained monotonic triaxial tests performed on samples reconstituted from Chlef River sand with 0, 10, 20, 30, 40, and 50% nonplastic silt at an effective confining stress of 100 kPa and two relative densities (D_r = 20, and 91%) are presented and discussed. It was found that the pore pressure increases linearly with the increase of the fines content and logarithmically with the increase of the intergranular void ratio. The results obtained from this study reveal that the saturated hydraulic conductivity (k) of the sand mixed with 50% low plastic fines can be, on average, four orders of magnitude smaller than that of the clean sand. The results show also that the hydraulic conductivity decreases hyperbolically with the increase of the fines content and the intergranular void ratio.  相似文献   

Experimental Study of Undrained Shear Strength of Silty Sand: Effect of Fines and Gradation   总被引：2，自引：1，他引：1  

Mostefa Belkhatir  Ahmed Arab  Noureddine Della  Tom Schanz 《Geotechnical and Geological Engineering》2012,30(5):1103-1118

Two strong earthquakes occurred in the region of Chlef (north western part of Algeria) during the last century. From the geological context, there were several great masses of sandy soil ejections on to the ground surface level and severe damages to civil and hydraulic structures. These damages were due to the soil liquefaction phenomenon. The objective of this laboratory investigation is to study the effect of low plastic fines and gradation characteristics on the undrained shear strength (liquefaction resistance) response of sand-silt mixture samples. For this purpose, a series of undrained monotonic triaxial tests were carried out on reconstituted saturated silty sand samples with different fines content ranging from 0 to 50?% at two initial relative densities (D_r?=?20 and 91?%). The initial confining pressure was kept at 100?kPa. The evaluation of the data indicates that the undrained shear strength at the peak (q_peak) can be correlated to the undrained residual strength (S_us), the excess pore pressure (Δu), the fines content (F_c) and the intergranular void ratio (e_s). The test results indicate also that the undrained shear strength at the peak decreases with the increment of the coefficient of uniformity and fines content as well as with the decrement of the mean grain size in the range of 0–50?% fines content for both relative densities (D_r?=?20 and 91?%).  相似文献   

Adakitic lavas in the Central Luzon back‐arc region,Philippines: lower crust partial melting products?   总被引：6，自引：0，他引：6  

Graciano P. Yumul JR    Carla Dimalanta  Herve Bellon  Decibel V. Faustino  Joel V. De Jesus  Rodolfo A. Tamayo  JR    Ferdinand T. Jumawan 《Island Arc》2000,9(4):499-512

Abstract Volcanism in the back-arc side region of Central Luzon, Philippines, with respect to the Manila Trench is characterized by fewer and smaller volume volcanic centers compared to the adjacent forearc side-main volcanic arc igneous rocks. The back-arc side volcanic rocks which include basalts, basaltic andesites, andesites and dacites also contain more hydrous minerals (ie, hornblende and biotite). Adakite-like geochemical characteristics of these back-arc lavas, including elevated Sr, depleted heavy rare earth elements and high Sr/Y ratios, are unlikely to have formed by slab melting, be related to incipient subduction, slab window magmatism or plagioclase accumulation. Field and geochemical evidence show that these adakitic lavas were most probably formed by the partial melting of a garnet-bearing amphibolitic lower crust. Adakitic lavas are not necessarily arc–trench gap region slab melts.  相似文献   

Analytical solution for 1D consolidation under haversine cyclic loading     

Sabah S. Razouki  Paul Bonnier  Maria Datcheva  Tom Schanz 《国际地质力学数值与分析法杂志》2013,37(14):2367-2372

Presented and discussed in this paper is an exact analytical solution of the nonhomogeneous partial differential equation governing the conventional one‐dimensional consolidation under haversine repeated loading. The derived analytical solution to the 1D consolidation equation is compared with the numerical solution of the same consolidation problem via FEM. The series solution takes into account the frequency of repeated loading through a dimensionless time factor T₀. The paper reveals that an increase in the frequency of imposed repeated haversine loading (a decrease in period of repeated loading) causes an increase in the number of cycles required to achieve the steady state, whereas the effect of frequency on the maximum excess pore water pressure at the bottom of a clay layer with permeable top and impermeable bottom for the range of frequencies studied is generally insignificant. The effective stress at the bottom of the clay deposit with permeable top and impermeable bottom increases with time but with some fluctuations without changing the sign. These fluctuations become more pronounced for increasing values of T₀. An increase in T₀ also causes an increase in maximum effective stress. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Messungen der Luftverschmutzung in Wien     

Ferdinand Steinhauser 《Theoretical and Applied Climatology》1960,10(2):200-209

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Limnological description of the Lakes Zürich, Lucerne, and Cadagno     

Peter Bossard  Sonja Gammeter  Christine Lehmann  Ferdinand Schanz  Reinhard Bachofen  Hans-Rudolf Bürgi  Daniel Steiner  Ulrich Zimmermann 《Aquatic Sciences - Research Across Boundaries》2001,63(3):225-249

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Prediction of algal growth in batch cultures     

Ferdinand Schanz  Ulrich Zahler 《Aquatic Sciences - Research Across Boundaries》1981,43(1):103-113

The growth of algae in batch cultures is often well characterized by the logistic growth function. The equation used contents three parameters which have to be estimated. Two methods are presented: The linearizing procedure, and the direct method of least squares. We give an example for comparing several logistic growth curves.  相似文献   

Analytical solutions to low-order spectral systems     

Prof Ferdinand Baer 《Meteorology and Atmospheric Physics》1970,19(3):255-282

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Average attenuation of 0.7–5.0  Hz Lg waves and magnitude scale determination for the region bounding the western branch of the East African Rift     

Richard W. Ferdinand 《Geophysical Journal International》1998,134(3):818-830

The investigation of L g attenuation characteristics in the region bounding the western branch of the East African rift system using digital recordings from a seismic network located along the rift between Lake Rukwa and Lake Malawi is reported. A set of 24 recordings of L g waves from 12 regional earthquakes has been used for the determination of anelastic attenuation, Q _Lg , and regional body-wave magnitude, m _{b Lg} , scale. The events used have body-wave magnitudes, m _b , between 4.6 and 5.5, which have been determined teleseismically and listed in ISC bulletins. The data were time-domain displacement amplitudes measured at 10 different frequencies (0.7–5.0  Hz). Q _Lg and its frequency dependence, η , in the region can be represented in the form Q _Lg = (186.2 ± 6.5)  f  ^(0.78±0.05). This model is in agreement with models established in other active tectonic regions. The L g -wave-based magnitude formula for the region is given by m _{b Lg} = log   A + (3.76 ± 0.38)  log   D − (5.72 ± 1.06), where A is a half-peak-to-peak maximum amplitude of the 1  s L g wave amplitude in microns and D is the epicentral distance in kilometres. Magnitude results for the 12 regional earthquakes tested are in good agreement with the ISC body-wave magnitude scale.  相似文献   

Atmospheric back radiation in the tropical pacific: Intercomparison of in-situ measurements, simulations and satellite retrievals   总被引：1，自引：0，他引：1  

L. C. Schanz  P. Schlüssel 《Meteorology and Atmospheric Physics》1997,63(3-4):217-226

Summary The back radiation has been measured with an Eppley pyrgeometer on board the R/V Vickers in the tropical Pacific Ocean during the field campaigns COARE (Coupled Ocean Atmosphere Response Experiment) and CEPEX (Central Equatorial Pacific Experiment) in February and March 1993, respectively. As part of these compaigns radiosondes have been launched from the Vickers several times per day and cloud cover was observed frequently. The radiosonde and cloud observations are used together with a radiative transfer model to calculate the back radiation for a subsequent intercomparison with the pyrgeometer measurements. Another means of comparison is derived from space-borne SSM/I (Special Sensor Microwave/Imager) measurements. The mean difference between pyrgeometer measurements and simulated downwelling irradiance at the sea surface is less than 2 W/m², at a mean of 425 W/m² in the warm pool, with a standard deviation of 8 W/m². The comparison of satellite measurements with pyrgeometer readings shows a mean difference of-3 W/m² and a standard deviation of 14 W/m². The mean difference between satellite-derived back radiation and simulated one is 3 W/m² with a standard deviation of 14 W/m². Comparisons with results obtained from bulk formulae applied to surface meteorological observations show a good performance of the bulk parameterisations in the cloud-free case but a general overestimation of the back radiation in cloudy situations.With 5 Figures  相似文献