Experimental Study on the Water-Induced Weakening of Calcarenites   总被引：4，自引：0，他引：4  

Matteo Oryem Ciantia  Riccardo Castellanza  Claudio di Prisco 《Rock Mechanics and Rock Engineering》2015,48(2):441-461

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Study in laboratory of treatment with cement of silty material: improvement of the mechanical properties     

Mokhtar Dadouch  Moulay Smaïne Ghembaza  Nour-Said Ikhlef 《Arabian Journal of Geosciences》2015,8(7):4329-4336

The addition of the agent of treatment allows to obtain a better traficability and improves the capacity of the soil to compaction while assuring a correct implementation. Besides, the binder provides to the soil a direct, maintained, or increasing lift at the same time. The choice of the agent of treatment and its dosage is determined by the type of soil, its moisture content at the time of the treatment, and by the aimed characteristics. The technique of treatment of soil in place in the hydraulic binders consists in valuing the natural soil (existing at the site of construction) by mixing them with a hydraulic binder and some water. It allows to avoid the transport and implies their stabilization in very interesting costs before the implementation of the superficial layers. In this context, this paper presents the results of the shear strength parameters of a study in laboratory with the aim of using the fine soil, in particular an Algerian western resulting silt, after a treatment with the cement by dry mixing method. Our goal is to realize pavement structures (base layer and subgrade layer) with this material. This type of treatment requires to know well the material which we wish to treat. A geotechnical complete characterization before treatment is approached on samples compacted in different water content, followed by the study of the influence of the addition of 2, 4, and 6 % cement on the characteristics of portance and of strength to shearing. Shear test was performed after curing the samples for 24 h to evaluate the shear strength parameters. The obtained results highlight a clearly better and marked improvement of the characteristics such as the lift and the strength to shearing.  相似文献   

Highly gravity-driven flow of a NAPL in water-saturated porous media using the discontinuous Galerkin finite-element method with a generalised Godunov scheme     

Lauriane Schneider  Raphaël di Chiara Roupert  Gerhard Schäfer  Philippe Helluy 《Computational Geosciences》2015,19(4):855-876

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A visco‐plastic constitutive model for granular soils modified according to non‐local and gradient approaches     

C. di Prisco  S. Imposimato  E. C. Aifantis 《国际地质力学数值与分析法杂志》2002,26(2):121-138

An already available non‐associated elastic–viscoplastic constitutive model with anisotropic strain hardening is modified in order to describe both the constitutive parameter dependency on relative density and the spatio‐temporal evolution of strain localization. To achieve this latter goal, two distinct but similar approaches are introduced: one inspired by the gradient theory and one by the non‐local theory. A one‐dimensional case concerning a simple shear test for a non‐homogeneous infinitely long dense sand specimen is numerically discussed and a finite difference scheme is employed for this purpose. The results obtained by following the two different approaches are critically analysed and compared. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Physical studies of asteroids XXX: the asteroid 153 Hilda     

C. -I. Lagerkvist  M. di Martino  C. Blanco  M. Dahlgren  A. Erikson  J. F. Lahulla  M. Lazzarin  K. Lumme  S. Pohjolainen  D. Riccioli 《Earth, Moon, and Planets》1995,71(3):189-194

The asteroid 153 Hilda was studied by photometric, spectroscopic and polarimetric observations during the apparition in 1992. The rotation period was determined to 5.11 hours with a lightcurve amplitude of 0.05 magnitudes. From our spectrum we find 153 Hilda to be of taxonomic type P. The polarization value of -0.23 at a phase angle of 3.2 degrees seems normal for a P-type asteroid. Long term integrations of the orbit shows that it is stable over time intervals of several million years.Partly based on observations collected at the European Southern Observatory, La Silla, Chile  相似文献   

Mechanical interpretation of dry granular masses impacting on rigid obstacles     

Calvetti  Francesco  di Prisco  Claudio  Redaelli  Irene  Sganzerla  Anna  Vairaktaris  Emmanouil 《Acta Geotechnica》2019,14(5):1289-1305

Acta Geotechnica - The evaluation of impact forces exerted by flowing granular masses on rigid obstacles is of fundamental importance for the assessment of the associated risk and for the design of...  相似文献   

A Time Monte Carlo method for addressing uncertainty in land-use change models     

Ahmed Mustafa  Ismaïl Saadi  Mario Cools  Jacques Teller 《International journal of geographical information science》2018,32(11):2317-2333

One of the main objectives of land-use change models is to explore future land-use patterns. Therefore, the issue of addressing uncertainty in land-use forecasting has received an increasing attention in recent years. Many current models consider uncertainty by including a randomness component in their structure. In this paper, we present a novel approach for tuning uncertainty over time, which we refer to as the Time Monte Carlo (TMC) method. The TMC uses a specific range of randomness to allocate new land uses. This range is associated with the transition probabilities from one land use to another. The range of randomness is increased over time so that the degree of uncertainty increases over time. We compare the TMC to the randomness components used in previous models, through a coupled logistic regression-cellular automata model applied for Wallonia (Belgium) as a case study. Our analysis reveals that the TMC produces results comparable with existing methods over the short-term validation period (2000–2010). Furthermore, the TMC can tune uncertainty on longer-term time horizons, which is an essential feature of our method to account for greater uncertainty in the distant future.  相似文献   

Space-time kriging of precipitation variability in Turkey for the period 1976–2010     

Raja  Nussaïbah B.  Aydin  Olgu  Türkoğlu  Necla  Çiçek  Ihsan 《Theoretical and Applied Climatology》2017,129(1-2):293-304

The purpose of this study is to revaluate the changing spatial and temporal trends of precipitation in Turkey. Turkey is located in one of the regions at greatest risk from the potential effects of climate change. Since the 1970s, a decreasing trend in annual precipitation has been observed, in addition to an increasing number of precipitation-related natural hazards such as floods, extreme precipitation, and droughts. An understanding of the temporal and spatial characteristics of precipitation is therefore crucial to hazard management as well as planning and managing water resources, which depend heavily on precipitation. The ordinary kriging method was employed to interpolate precipitation estimates using precipitation records from 228 meteorological stations across the country for the period 1976–2010. A decreasing trend was observed across the Central Anatolian region, except for 1996–2000 which saw an increase in precipitation. However, this same period is identified as the driest year in Eastern and South Eastern Anatolia. The Eastern Black Sea region has the highest precipitation in the country; after 1996, an increase in annual precipitation in this region is observed. An overall reduction is also seen in southwest Turkey, with less variation in precipitation.

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TritonX-100－5-Br-PADAP光度法测定铜和镍   总被引：2，自引：0，他引：2  

萨木嘎  刘颖  嘎日迪 《岩矿测试》1999,18(4):5

研究了非离子型表面活性剂Ｔｒｉｔｏｎ Ｘ－ １００ 存在下,用５ － Ｂｒ － ＰＡＤＡＰ 光度法测定铜、镍的方法。结果表明：在ｐＨ９ ．０ 的硼砂缓冲介质中,５ － Ｂｒ － ＰＡＤＡＰ 与铜和镍生成紫红色络合物,λＣｕｍ ａｘ ＝ ５７５ ｎｍ ,εＣｕ ＝ １ ．０４ ×１０５ Ｌ·ｍｏｌ－ １·ｃｍ － １ ;λＮｉｍ ａｘ ＝ ５７５ ｎｍ ,εＮｉ ＝ １ ．１４ ×１０５ Ｌ·ｍｏｌ－ １·ｃｍ － １ 。铜和镍的质量浓度分别在０ ～５６０ μｇ／ Ｌ和０ ～４４０ μｇ／ Ｌ符合比尔定律。加入六偏磷酸钠后,由于偏磷酸镍的形成,镍不再与５ － Ｂｒ － ＰＡＤＡＰ 显色,可通过铜及铜镍总量的测定,计算出镍的含量。用该方法实测了钢样中铜和镍的含量,结果与推荐值相符,对铜和镍５ 次测定的ＲＳＤ均小于５ ％ 。  相似文献   

Geodynamic Evolution of Northeastern Tunisia During the Maastrichtian–Paleocene Time: Insights from Integrated Seismic Stratigraphic Analysis     

Oussama Abidi  Mohamed Hédi Inoubli  Kawthar Sebei  Adnen Amiri  Haifa Boussiga  Imen Hamdi Nasr  Abdelhamid Ben Salem  Mahmoud Elabed 《Surveys in Geophysics》2017,38(3):617-649

The Maastrichtian–Paleocene El Haria formation was studied and defined in Tunisia on the basis of outcrops and borehole data; few studies were interested in its three-dimensional extent. In this paper, the El Haria formation is reviewed in the context of a tectono-stratigraphic interval using an integrated seismic stratigraphic analysis based on borehole lithology logs, electrical well logging, well shots, vertical seismic profiles and post-stack surface data. Seismic analysis benefits from appropriate calibration with borehole data, conventional interpretation, velocity mapping, seismic attributes and post-stack model-based inversion. The applied methodology proved to be powerful for charactering the marly Maastrichtian–Paleocene interval of the El Haria formation. Migrated seismic sections together with borehole measurements are used to detail the three-dimensional changes in thickness, facies and depositional environment in the Cap Bon and Gulf of Hammamet regions during the Maastrichtian–Paleocene time. Furthermore, dating based on their microfossil content divulges local and multiple internal hiatuses within the El Haria formation which are related to the geodynamic evolution of the depositional floor since the Campanian stage. Interpreted seismic sections display concordance, unconformities, pinchouts, sedimentary gaps, incised valleys and syn-sedimentary normal faulting. Based on the seismic reflection geometry and terminations, seven sequences are delineated. These sequences are related to base-level changes as the combination of depositional floor paleo-topography, tectonic forces, subsidence and the developed accommodation space. These factors controlled the occurrence of the various parts of the Maastrichtian–Paleocene interval. Detailed examinations of these deposits together with the analysis of the structural deformation at different time periods allowed us to obtain a better understanding of the sediment architecture in depth and the delineation of the geodynamic evolution of the region.  相似文献