Modified borehole jack method for elastic property determination in rocks     

R. V. de la Cruz 《Rock Mechanics and Rock Engineering》1978,10(4):221-239

SummaryModified Borehole Jack Method for Elastic Property Determination in Rocks This paper describes a method of determining thein-situ elastic properties of rock masses with friction-strain gauges and a lengthened borehole jack.The method involves impressing tangentially-oriented friction gauges on opposite quadrants of a borehole wall, while the remaining quadrants are loaded by the borehole jack with a unidirectional self-equilibrating pair of forces. The tangential normal strains generated at the borehole wall are thus measured concurrently with the loading. To determine the modulus of the rock mass, equations were developed relating the measured tangential normal strains and the applied ram pressures.Several factors which may influence the interpretation of data were thoroughly analyzed. It was shown that variations in the pressure distribution and area of plate-wall contact have negligible effects on the accuracy of data interpretation. End effects were minimized by lengthening the jack and carrying out strain measurements at the central region only where stresses and strains are homogeneous and plane strain conditions exist.The new method has the same desirable mechanical and operational features as the well-known Goodman-Jack method. Most important, however, its theoretical basis is exact with no estimated coefficients required in the reduction of observed data. While the method requires an ideal elastic material, it has a number of other applications for in-situ measurements besides modulus determination. The modified method could be utilized for determining linearity, anisotropy, inhomogeneity, tensile strength and, with an additional operation, the in-situ stress field.

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ZusammenfassungModifizierte Methode zur Bestimmung der elastischen Kenngröen von Fels mittels einer Bohrlochaufweitungssonde Es wird eine Methode zur Bestimmung der elastischen Kenngrößen von Fels aus In-situ-Versuchen mittels Reibungs-Dehn-meßstreifen und einer verlängerten Bohrlochaufweitungssonde beschrieben.Tangential orientierte Reibungsmeßstreifen werden an gegenüberliegenden Quadranten des Bohrloches angebracht, während die beiden anderen Quadranten mit der Bohrlochaufweitungssonde belastet werden, um Belastung und Verformung gleichzeitig zu messen. Gleichungen wurden entwickelt um daraus den Modul der Steinmasse zu bestimmen.Es wird gezeigt, daß eine ungleichmäßige Verteilung des Druckes und die Platten-Wand-Kontaktfläche einen unbedeuteten Einfluß auf die Exaktheit der Ergebnisse haben. Randeinflüsse wurden verringert, indem Messungen nur in der Mitte der Sonde ausgeführt wurden.Diese neue Methode hat dieselben Vorteile wie die bekannte Goodman-Jack Methode. Am wichtigsten ist aber, daß ihre theoretische Basis exakt ist. Obwohl die Methode nur in einem ideal elastischen Material anwendbar ist, kann sie außer für Modul-Bestimmung auch für andere In-situ-Messungen gebraucht werden, wie z. B. Linearität, Anisotropie, Inhomogenität, Zugfestigkeit und den primären Spannungszustand.

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RésuméMéthode modifiée pour déterminer les repères élastiques de rochers par une sonde d'élargissement de trous de sonde Cet article décrit une méthode de mesure des propriétés élastiquesin-situ des masses rocheuses, à l'aide d'indicateurs de déformation à friction, et d'un vérin alongé pour trou de sondage.La méthode consiste à imprimer des indicateurs de déformation à friction sur les quadrants opposés de la paroie d'un trou de sondage, et à charger les deux autre quadrants avec deux forces de même direction qui s'équilibrent, utilisant le vérin pour trou de sondage. Les déformations tangentielles normales créées sur la paroie du trou de sondage sont ainsi mesurées avec la charge correspondante. Afin de pouvoir déterminer le module d'élasticité de la masse rocheuse on a développé les équations qui relient les déformations normales tangentielles mesurées aux pressions appliquées.On a analysé en detail plusieurs facteurs qui pourraient influencer l'interprétation des données. On a montré que des variations dans la distribution de la pression, et dans la surface de contact entre le piston et la paroie, ont un effet négligeable sur la précision de l'interprétation des données. Les effets d'extrémités ont été réduits au minimum en alongeant le piston, et en ne mesurant les déformations que dans la région centrale, où les contraintes et déformations sont homogènes et des conditions de deformation plane existent.La nouvelle méthode a les mêmes caractéristiques mécaniques et opérationnelles désirables que la méthode bien connue Goodman-Jack. Encore plus important est le fait que sa base théorique est exacte, et il n'est pas nécessaire d'utiliser des coefficients estimés pour réduire les résultats observés. Bien que la méthode exige un milieu élastique idéal, elle peut être utilisée pour des mesuresin-situ autres que les mesures du module d'élasticité. La méthode modifiée pourrait être utilisée pour déterminer la linéarité, l'anisotropie, le manque d'homogénéité, la résistance à la traction et, avec une opération supplémentaire, le champ des forcesin-situ.

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A spectral analysis of Iberian Peninsula monthly rainfall   总被引：2，自引：0，他引：2  

J. A. García  A. Serrano  M. de la Cruz Gallego 《Theoretical and Applied Climatology》2002,71(1-2):77-95

Summary A spectral analysis of Iberian Peninsula monthly rainfall series was carried out. The data set consists of monthly precipitation records from 40 meteorological observatories over 74 years (1919–1992). The stations are representative of most of the Iberian Peninsula. The rainfall series were analyzed spatially by means of Principal Component Analysis (PCA) and temporally by means of the Multi-Taper Method (MTM) of spectral analysis of by Monte-Carlo Singular Spectrum Analysis (MCSSA). The PCA gave six dominant modes of variation which explain 75% of the variance with each component affecting a different region of the Peninsula. The spectral analysis showed 7 year oscillations for the dominant pattern and 2.7 and 16 years for the third pattern. The 7-year oscillation seems to be related to other climatic oscillations recorded in the northern hemisphere while the 2.7-year oscillation could be related to the ENSO phenomenon. Received July 18, 2000 Revised April 19, 2001  相似文献   

Sediment community metabolism associated with continental shelf hypoxia, Northern Gulf of Mexico   总被引：1，自引：0，他引：1  

Gilbert T. Rowe  Marta Elizabeth Cruz Kaegi  John W. Morse  Gregory S. Boland  Elva G. Escobar Briones 《Estuaries and Coasts》2002,25(6):1097-1106

Net fluxes of respiratory metabolites (O₂, dissolved inorganic carbon (DIC), NH₄ ⁺, NO₃ ^?, and NO₂ ^?) across the sediment-water interface were measured using in-situ benthic incubation chambers in the area of intermittent seasonal hypoxia associated with the Mississippi River plume. Sulfate reduction was measured in sediments incubated with trace levels of³⁵S-labeled sulfate. Heterotrophic remineralization, measured as nutrient regeneration, sediment community oxygen consumption (SOC), sulfate reduction, or DIC production, varied positively as a function of temperature. SOC was inversely related to oxygen concentration of the bottom water. The DIC fluxes were more than 2 times higher than SOC alone, under hypoxic conditions, suggesting that oxygen uptake alone cannot be used to estimate total community remineralization under conditions of low oxygen concentration in the water column. A carbon budget is constructed that compares sources, stocks, transformations, and sinks of carbon in the top meter of sediment. A comparison of remineralization processes within the sediments implicates sulfate reduction as most important, followed by aerobic respiration and denitrification. Bacteria accounted for more than 90% of the total community biomass, compared to the metazoan invertebrates, due presumably to hypoxic stress.  相似文献   

Crustal Thermal Structure of the Brazilian Equatorial Margin Using Fourier and Continuous Wavelet Transforms: A Comparative Analysis Based on Different Magnetic Datasets     

Herrera  Duvan Ricardo Herrera  de Castro  David Lopes  Oliveira  Jefferson Tavares Cruz  de Oliveira  Di&#;genes Cust&#;dio 《Surveys in Geophysics》2022,43(3):883-912

Surveys in Geophysics - In this work, we calculated the Curie Point Depth (CPD) for the Brazilian Equatorial Margin using the Fourier and continuous wavelet (CWT) transforms considering a linear...  相似文献   

Bedrock bedding,landsliding and erosional budgets in the Central European Alps   总被引：4，自引：0，他引：4       下载免费PDF全文

Fábio Cruz Nunes  Romain Delunel  Fritz Schlunegger  Naki Akçar  Peter W. Kubik 《地学学报》2015,27(5):370-378

We explore the controls of the litho‐tectonic architecture on the erosional flux in the 370‐km² Glogn basin (European Alps). In this basin, the bedding and schistosity of the bedrock dip parallel to the topographic slope on the NW valley flank, leading to a non‐dip slope situation on the opposite SE valley side. While the dip slope condition has promoted the occurrence of landslides (e.g. the c. 30‐km² deep‐seated Lumnezia landslide), the opposite non‐dip slope side of the valley hosts >100‐m‐deeply incised tributary streams. ¹⁰Be concentrations of stream sediments yield catchment‐averaged denudation rates that vary between 0.27 ± 0.03 and 2.19 ± 0.37 mm a^?1, while the spatially averaged denudation rate of the entire basin is 1.99 ± 0.34 mm a^?1. Our ¹⁰Be‐based approach reveals that the Lumnezia landslide front contributes c. 30–65% of the entire sediment budget, although it covers <5% of the Glogn basin. This suggests a primary control of the bedrock bedding on erosion rates and processes.  相似文献   

Vegetation evolution by ecological succession as a potential bioindicator of landslides relative age in Southwestern Mediterranean region     

Lopes  Luís Filipe  Oliveira  Sérgio Cruz  Neto  Carlos  Zêzere  José Luís 《Natural Hazards》2020,103(1):599-622

Natural Hazards - Landslides have a direct impact in the ecosystems dynamics being considered one of the main vegetation perturbation processes. Our objective is to determine the relation between...  相似文献   

Competition Between Littoral Cladocerans Macrothrix triserialis and Alona rectangula (Cladocera) in Relation to Algal Food Level and Inoculation Density     

S. Nandini  Gloria Muro‐Cruz  S. S. S. Sarma 《洁净——土壤、空气、水》2002,30(1):16-23

We studied the relative competitive abilities of littoral cladocerans M.triserialis and A. rectangula using green algal food at two levels (0.5 · 10⁶ and 2 · 10⁶ cells mL⁻¹ of Chlorella) under five different inoculation ratios. Both the cladoceran species were influenced by food availability and mutual competitive pressure. Macrothrix could withstand competition better under conditions of lower food availability while Alona grew better, despite competition, when more Chlorella was available. Population growth rates (r) ranged from 0.022…0.070 for Alona and from 0.024…0.075 for Macrothrix. There was a significant impact of the inoculation ratio on the maximal population density reached by either test species. Food concentration had a significant influence on the peak population density reached only for Alona rectangula. Data on the body sizes of M. triserialis and A. rectangula showed that there was a higher somatic growth with increasing food availability and decreased competitive pressure in both the test species. In Macrothrix, food concentration and the competition from Alona through different initial inoculation densities had a significant impact on the body size. At the lower food concentration, the body size was significantly smaller when the inoculation density was lowest (highest competitive pressure). The body size of Alona, on the other hand, was not affected by the competition but was significantly higher under conditions of greater food availability. These results have been discussed in light of different theories of competition.  相似文献   

Parametric model identification of high-speed craft dynamics     

Rocío Muñoz-Mansilla  Joaquín Aranda  José Manuel Díaz  J de la Cruz 《Ocean Engineering》2009,36(12-13):1025-1038

Parametric models of heave, pitch and roll dynamics of a high-speed craft have been estimated for different wave incidence angles in the frequency domain. Several issues that make the identification problem interesting are the following: type of parameterization, starting values, non-quadratic functions, excitation signals and short data record. The method employed guarantees a fine linear approximation of the nonlinear dynamics of a fast ship for the ultimate goal of stabilization control to reduce motion sickness associated with heave, pitch and roll accelerations. In addition, the approach achieves high-quality starting values and avoids non-quadratic terms in the cost function, which results in less computational load and significantly more accurate models when compared with a previous method employed for the same problem.  相似文献   

Analyses of bottom simulating reflections offshore Arauco and Coyhaique (Chile)   总被引：1，自引：1，他引：0  

Ivan de la Cruz Vargas Cordero  Umberta Tinivella  Flavio Accaino  Maria Filomena Loreto  Francesco Fanucci  Christian Reichert 《Geo-Marine Letters》2010,30(3-4):271-281

Two seismic sections offshore Arauco and Coyhaique, Chile, have been analysed to better define the seismic character of hydrate-bearing sediments. The velocity analysis was used to estimate the gas-phase concentration, which can serve to correlate hydrate presence to the geological features. The velocity model allowed us to recognise the hydrate layer above the bottom simulating reflector (BSR), and the free gas layer below it. The velocity field is affected by strong lateral variation, showing maximum (above the BSR) and minimum (below the BSR) values in the southern sector. Here, highest gas hydrate and free gas concentrations were calculated (15% and 2.7% of total volume respectively). The estimated geothermal gradient ranges from 35 to 95°C/km. In the northern sector, the highest gas hydrate and free gas concentrations are 15% and 0.2% of total volume respectively, and the geothermal gradient is uniform and equal to about 30°C/km.  相似文献   

Aeromonas veronii, a tributyltin (TBT)-degrading bacterium isolated from an estuarine environment, Ria de Aveiro in Portugal   总被引：1，自引：0，他引：1  

Cruz A  Caetano T  Suzuki S  Mendo S 《Marine environmental research》2007,64(5):639-650

Organotin compounds are used in a variety of industrial processes therefore their subsequent discharge into the environment is widespread. Bacteria play an important role in biogeochemical transformations acting as natural decontamination agents. Therefore, screening for tributyltin (TBT)-resistant and -degrading bacteria is relevant for the selection of isolates with decontamination ability of these polluted areas. With this purpose, 50 strains were isolated from sediment and water from Ria de Aveiro and their tolerance to TBT, up to 3mM, was evaluated. Generally, occurrence of highly TBT-resistant bacteria was observed, and Gram negative bacteria exhibited more tolerance to TBT than Gram positive bacteria. A memory response was observed when bacteria were progressively exposed to increasingly higher TBT concentrations. One isolate, Aeromonas veronii Av27, highly resistant to TBT (3mM) uses this compound as carbon source and degrades it to less toxic compounds.  相似文献