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151.
Summary The modified borehole jacking method, as introduced by De La Cruz in 1978, has important theoretical advantages over the common method which is associated with the name Goodman. So far, however, the modified method has not succeeded, mainly due to a lack of suitable instrumentation. To overcome this problem, a new type of modified borehole jack has been designed, built and tested. The new jack incorporates two highly innovative components: a recoverable sensor for measuring tangential strain at borehole surfaces and stacked hydraulic cylinders for extra-high load outputs.The new jack has been developed to the point at which its technical feasibility under field conditions, including its capability of yielding meaningful results, is demonstrated. Calibration in a hollow steel cylinder revealed that the new modified jack yields the correct Young's modulus within an error margin of less than ±5%. In-situ jacking tests were carried out at a major dam construction site. Results were obtained from both common and modified borehole jacking and from conventional laboratory testing of drill cores. The results of these tests are presented and discussed against the background of the particular rock conditions at the site. 相似文献
152.
Günter Bock 《Physics of the Earth and Planetary Interiors》1981,25(4):360-371
P-wave travel-time residuals at the Warramunga Seismic Array (WRA) in the Northern Territory, Australia, have been studied from 49 earthquakes with epicenters south of 19°S in the Fiji-Tonga region. Focal depths are between 42 and 679 km as determined from pP-P. Using the Jeffreys-Bullen and the Herrin travel-time tables the epicentral parameters have been redetermined by considering only “normal” seismic stations in the location procedure. These are those stations where P-wave travel times are probably not affected by lateral heterogeneities caused by the lithosphere descending beneath the Tonga trench. Epicenters of deep earthquakes below 300 km have been relocated by using stations at Δ > 25° only. Epicenters from shallower-depth earthquakes have been recalculated without using stations between 35 < Δ < 75° epicentral distance. In both cases focal depths were determined from pP-P times. The resulting pattern of P-residuals at WRA does not show any significant change with depth below 350 km. The residuals become more negative for shallower earthquakes above about 250 km. P-waves to WRA are advanced by approximately 2 s compared with those from deep earthquakes. The results do not essentially differ for the two different travel-time tables used. The observations can be interpreted by P-wave velocities that are higher in the sinking slab down to 350–400 km by 5±2% than in both the Jeffreys-Bullen and Herrin models. Without considering possible elevations of phase boundaries this estimate yields a temperature contrast of 1000±450°C between slab and normal mantle material in this depth range. 相似文献
153.
Yu. N. Korenkov Carl W. Cable Vernon F. Cormier Vassily Levin Jacek A. Majorowicz Yehuda Bock Waclaw M. Zuberek Teng-fong Wong William L. Power Gary A. Robbins Piotr Raczka Krzysztof E. Haman Katarzyna Chałasinska-Macukow Ryszard Balcer Henryk Piwkowski 《Pure and Applied Geophysics》1991,137(3):309-336
154.
155.
Investigating evidential reasoning for the interpretation of microbial water quality in a distribution network 总被引:1,自引:1,他引:1
Rehan Sadiq Homayoun Najjaran Yehuda Kleiner 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,21(1):63-73
Total coliforms are used as indicators for evaluating microbial water quality in distribution networks. However, total coliform provides only a weak “evidence” of possible fecal contamination because pathogens are subset of total coliform and therefore their presence in drinking water is not necessarily associated with fecal contamination. Heterotrophic plate counts are also commonly used to evaluate microbial water quality in the distribution networks, but they cover even a wider range of organisms. As a result, both of these indicators can provide incomplete and highly uncertain bodies of evidence when used individually. In this paper, it is shown that combing these two sources of information by an appropriate data fusion technique can provide improved insight into microbial water quality within distribution networks. Approximate reasoning methods like fuzzy logic and probabilistic reasoning are commonly used for data fusion where knowledge is uncertain (i.e., ambiguous, incomplete, and/or vague). Traditional probabilistic frameworks like Bayesian analysis, reasons through conditioning based on prior probabilities (which are hardly ever available). The Dempster–Shafer (DS) theory generalizes the Bayesian analysis without requiring prior probabilities. The DS theory can efficiently deal with the difficulties related to the interpretation of overall water quality where the redundancy of information is routinely observed and the credibility of available data continuously changes. In this paper, the DS rule of combination and its modifications including Yager’s modified rule, Dubois–Prade disjunctive rule and Dezert–Smarandache rule are described using an example of microbial water quality in a distribution network. 相似文献
156.
157.
Anton Eisenhauer Thomas F. Nägler Peter Stille Jan Kramers Nikolaus Gussone Barbara Bock Jan Fietzke Dorothee Hippler Anne-Désirée Schmitt 《Geostandards and Geoanalytical Research》2004,28(1):149-151
A proposal is made to standardise the reporting of Ca isotope data to the δ44 Ca/40 Ca notation (or δ44 Ca/42Ca) and to adopt NIST SRM 915a as the reference standard. 相似文献
158.
A wide-angle airborne laser ranging system (WA-ALRS) is developed at the Institut Géographique National (IGN), France, with
the aim of providing a new geodesy technique devoted to large (100 km2) networks with a high density (1 km−2) of benchmarks. The main objective is to achieve a 1-mm accuracy in relative vertical coordinates from aircraft measurements
lasting a few hours. This paper reviews the methodology and analyzes the first experimental data achieved from a specific
ground-based experiment. The accuracy in relative coordinate estimates is studied with the help of numerical simulations.
It is shown that strong accuracy limitations arise with a small laser beam divergence combined with short range measurements
when relatively few simultaneous range data are produced. The accuracy is of a few cm in transverse coordinates and a few
mm in radial coordinates. The results from ground-based experimental data are fairly compatible with these predictions. The
use of a model for systematic errors in the vehicle trajectory is shown to be necessary to achieve such a high accuracy. This
work yields the first complete validation of modelization and methodology of this technique. An accuracy better than 1 mm
and a few mm in vertical and horizontal coordinates, respectively, is predicted for aircraft experiments.
Received: 19 June 1997 / Accepted: 17 February 1998 相似文献
159.
Guided Waves from Sources Outside Faults: An Indication for Shallow Fault Zone Structure? 总被引:1,自引:0,他引:1
Miko Fohrmann Heiner Igel Gunnar Jahnke Yehuda Ben-Zion 《Pure and Applied Geophysics》2004,161(11-12):2125-2137
— Using 3-D numerical modeling of seismic wave propagation we investigate the possibility of generating fault zone (FZ) trapped wave energy from sources well outside a fault. The FZ is represented by a O(200 m) wide vertical low velocity layer in a half space. We find that FZ trapped waves can be excited from sources well outside the fault if (1) the low-velocity structure extemds only to shallow depth and the source is located at greater depth or (2) the structure of the low-velocity zone is such that only the shallow part of the FZ traps energy. FZ trapped waves are not excited from sources well outside a FZ continuous with depth. The results support, in conjunction with recent observational evidence, a model for natural faults with shallow trapping structures rather than ones that span the entire seismogenic zone. This may have implications for fault mechanics as well as for aspects of shaking hazard near faults. 相似文献
160.