Time and space variant soil properties at a liquefied site were simultaneously identified in the time domain by using borehole array strong motion records. During soil liquefaction at a site, soils usually show a wide variety of non-linear behavior along the depth as well as non-stationary behavior. Strong ground motion records were obtained at Port Island borehole array observatory, Kobe, during the 1995 Hyogoken-Nanbu earthquake. In this study, the instrumented soil was modeled by the equivalent linear MDOF system, and an extended Kalman filter with local iteration was employed for the identification of the soils. The identification process was successfully conducted, and the stress–strain relationships of the soils at the liquefied site were obtained from different depths all at once. 相似文献
Methods for the identification of models for hydrological forecasting have to consider the specific nature of these models
and the uncertainties present in the modeling process. Current approaches fail to fully incorporate these two aspects. In
this paper we review the nature of hydrological models and the consequences of this nature for the task of model identification.
We then continue to discuss the history (“The need for more POWER‘’), the current state (“Learning from other fields”) and
the future (“Towards a general framework”) of model identification. The discussion closes with a list of desirable features
for an identification framework under uncertainty and open research questions in need of answers before such a framework can
be implemented. 相似文献
INTRODUCTIONThe structural mine earthquake in coal mines refers to the quake induced by excavationengineeringthatleadstorupturingor change of geological structure and weakness surfaceintheinteriorof rock mass.According to the origin,mine earthquakes can b… 相似文献
Sand-rich submarine fans are radial or curved in plan view depending on the slope of the basin floor. They occur isolated or in coalescing systems. The fans' average lateral extent measures close to 25 km and their thickness usually less than 300 m. The thickness of outer fan sequences averages around 120 m and that of middle fan successions around 160 m. Rarely reported inner fan sequences have a maximum thickness of 80 m.
The formation of sand-rich fans is closely related to tectonic activity. Their sediment is coarse-grained and compositionally immature as indicated by significant feldspar content due to close provenance and rapid transport by short rivers with a steep gradient controlled by tectonism. Tectonic activity also provides for narrow shelves making the fans relatively insensitive to sealevel changes. Formation of sand-rich fans typically occurs in restricted continental basins. The tectonic settings are highly variable. Sand-rich fans typically receive their sediment through submarine canyons which intercept sand from longshore drift and/or are fed more or less directly by regional rivers.
The type of ancient fan system (radial, curved, isolated, coalescing) may be identified through paleocurrent map plots, facies map sketches, recognition of lateral thickness variations and sediment influx centers, as well as lateral bed correlations defining the minimum fan extent.
Important in distinguishing different environments of ancient fans are detailed measured sections, their comparison and correlation. Channelized inner fan and middle fan deposits may be distinguished from the unchannelized outer fan successions through bed correlation tests which reflect their different stratigraphic architectures and bedding patterns. Bedding in outer fan deposits (lobes) is relatively simple, parallel, and regular. The lateral bed continuity is relatively high. Channel fills, especially those of middle fan distributary channels, display a complicated bedding pattern with vertical and lateral random distribution of channel fills, axial erosion, and bed convergence towards the channel margins. Channel fills exhibit only linear bed continuity. Thus, the probability in carrying out local to regional scale lateral bed correlations is almost exclusively limited to outer fan deposits.
The measured sections will help further distinguish fan environments by revealing: (1) different facies associations in outer fan sequences (mainly B, C and D) and middle fan successions (mainly A, B, C, D, and channel margin facies); (2) greater average bed and layer thicknesses in middle fan as opposed to outer fan successions (“bed” and “layer” as used herein); (3) more frequent amalgamation surfaces in channel fills than in unchannelized outer fan deposits; (4) more frequent tabular amalgamation surfaces in outer fan sections; (5) more frequent nontabular amalgamation surfaces in channel fills; and (6) more frequent dish structures in middle fan than outer fan successions.
Rarely exposed fan valley fills may be identified by coarse conglomerates. Moreover, in proximity to fan valley fills, relatively mud-rich sediments may be observed that derive from the depositional system of the basin slope. 相似文献
In the underground waste isolation projects such as the ANDRA'one in the site of Bure, the transport properties of the surrounding rock mass is of fundamental importance. To measure very low permeability, we use the modified version of the pulse test proposed by Hsieh et al. [Hsieh, P.A., Tracy, J.V., Neuzil, C.E., Bredehoeft, J.D., Silliman, S.E., 1981. A transient laboratory method for determining the hydraulic properties of ‘tight’ rocks — I. Theory. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. Vol. 18, pp. 245-252] which enables the intrinsic permeability, k, and the specific storage coefficient, Ss, of rocks such as mudstone to be characterized. In this paper, the special effort performed on the laboratory apparatus design, to ensure a good sensitivity of the rock response with respect to both parameters, k and Ss, is presented. In addition, two parameters identification procedures are proposed: the graphical method given by Hsieh et al. [Hsieh, P.A., Tracy, J.V., Neuzil, C.E., Bredehoeft, J.D., Silliman, S.E., 1981. A transient laboratory method for determining the hydraulic properties of ‘tight’ rocks — I. Theory. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. Vol. 18, pp. 245-252] and a parameter identification based on the solution of an inverse problem. The efficiency of the apparatus design and the parameters identification procedures is then demonstrated though some pulse tests performed on the Meuse/Haute-Marne mudstone. 相似文献
In the identifying process of an oil spill accident, manual integral and artificial visual comparison are commonly used at present to determine the oil spill sources, these methods are time-consuming and easily affected by human factors. Therefore, it is difficult to achieve the purpose of rapid identification of an oil spill accident. In this paper, an intelligent method of automatic recognition, integration and calculation of diagnostic ratio of Gas Chromatography-Mass Spectrometer (GC/MS) spectrum are established. Firstly, four hundreds of samples collected around the world were analyzed using a standard method and Retention time locking technology (RTL) was applied to reduce the change of retention time of GC/MS spectrum. Secondly, the automatic identification, integration of n-alkanes, biomarker compounds, polycyclic aromatic hydrocarbons and calculation of the diagnostic ratios were realized by MATLAB software. Finally, a database of oil fingerprints were established and applied successfully in a spill oil accident. Based on the new method and database, we could acquire the diagnostic ratios of an oil sample and find out the suspected oil within a few minutes. This method and database can improve the efficiency in spilled oil identification. 相似文献
