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101.
随着三峡水利工程的逐步实施,淹没区移民及新城镇建设等人类工程活动的加剧,以滑坡为主的环境地质问题日益突出。本文从稳定系数、安全系数入手,对铁道、公路等部门常用的设计计算原理进行了研究,并由此类比分析研究了三峡区回水后或库水位正常运行条件下,滑坡治理工程设计计算方法。 相似文献
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电磁波CT技术在探测堤坝工程中的应用 总被引:4,自引:0,他引:4
应用电磁波CT探测技术对流溪何竹料段大堤和丰顺县虎局水库大坝渗水通道进行了探测研究,由于电磁波的吸收系数和地层结构有密切关系,因此,电磁波CT是通过能量的变化观测反演吸收系数的分布,进而推测地下构造的分布,利用电磁波的吸收系数为层析物理量,在钻孔中进行透射观测,以优于0.5m的分辨率清楚地揭示了测区内渗水层位的分布情况。 相似文献
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An experiment on evapotranspiration from citrus trees under irrigation with saline waterwas carried out for 4 months. Two lysimeters planted with a citrus tree in the green house wereused. One lysimeter was irrigated with saline water (NaCl and CaCl2 of 2000 mg/L equivalence,EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. Theapplied irrigation water was 1.2 times that of the evapotranspiration on the previous day.Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes.The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows.(i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. Theevapotranspiration returns to normal after leaching. However it takes months to exhaust the saltfrom the tree. ( ii ) To estimate the impact of irrigation with saline water on the evapotranspirationfrom citrus trees, the reduction coefficient due to salt stress (Ks) was used in this experiment.Evapotranspiration under irrigation with saline water (ETs) can be calculated from evapotranspira-tion under irrigation with freshwater (ET) by the equation ETs = Ks× ET. Ks can be expressed as afunction of ECsw. (iii) The critical soil-water electrical conductivity (ECsw) is 9.5 dS/m, beyondwhich adverse effects on evapotranspiration begin to appear. If ECsw can be controlled at below9.5 dS/m, saline water can be safely used for irrigation. 相似文献
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Audrey GalvéAlfred Hirn Jiang MeiJosep Gallart Béatrice de VoogdJean-Claude Lépine Jordi DiazWang Youxue Qian Hui 《Earth and Planetary Science Letters》2002,203(1):35-43
New wide-angle reflection and refraction seismic data provide constraints on the structure of the upper lithosphere, and test models of its evolution to raise the northeastern part of the Tibetan Plateau. Amplitudes observed for reflections from the crust-mantle boundary are sufficiently large to suggest that there is no significant partial melt in the deep crust. The data show an increase of the crustal thickness between terranes from north of the Kun Lun Fault into the Qang Tang of central Tibet, and a contrast among their intracrustal images and compositions. In the north, P and S velocities are consistent with a dominantly felsic composition and show that only the upper crust thickened. South of the Kun Lun Fault a thicker crust made of two layers could result from the superposition of the originally thin crust of the Bayan Har terrane on the lower part of the crust of the domain to the north, which upper crust it shoved and thickened. Different modes of crustal thickening, either by thickening of individual layers or superpositions and imbrication among them appear to work jointly to raise the topography. 相似文献
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Comparison of Seismic Dispersion and Attenuation Models 总被引:2,自引:0,他引:2
The frequency-dependent attenuation of seismic waves causes decreased resolution of seismic images with depth, and the difference in transmission losses induces amplitude variations with offset. Transmission losses may occur due to friction or fluid movement, or may result from scattering in thin-layer. Whatever the physical mechanism, they can often be conveniently described using an empirical formulation wherein the elastic moduli and propagation velocity are complex functions of frequency.We have compiled and compared algebraically and numerically eight different models involving complex velocity: the Kolsky-Futterman model, the power-law model, Kjartansson's model, Müller's model, Azimi's second and third model, the Cole-Cole model, and the standard linear-solid model.For two different parameter sets, the attenuation and phase velocity are computed in the seismic frequency band, and the plane-wave propagation of a Ricker wavelet for the other models is compared with that for the Kolsky-Futterman model. The first parameter set consists of parameters for each of the models calculated from expressions given in the appendix. These expressions make the different models behave similarly to the KF model. The second parameter set consists of model parameters that are numerically adapted to the KF model.By selecting proper parameters, all models, except the standard linear-solid model, show behavior similar to that of the Kolsky-Futterman model. The SLS model behaves differently from the other models as the frequency goes to zero or infinity. Broadband measurement data is needed to select a specific model for a given seismic experiment. 相似文献
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Reservoir models have large uncertainty because of spatial variability and limited sample data. The ultimate aim is to use simultaneously all available data sources to reduce uncertainty and provide reliable reservoir models for resource assessment and flow simulation. Seismic impedance or some other attribute provides a key source of data for reservoir modeling. These seismic data are at a coarser scale than the hard well data and it not an exact measurement of facies proportions or porosity. A requirement for data integration is the cross-covariance between the well and seismic data.The size-scaling behavior of the cross correlation for different measurement scales was nvestigated. The size-scaling relationship is derived theoretically and validated by numerical studies (including an example with real data). The limit properties of the cross-correlation coefficient when the averaging volume becomes large is shown. After some averaging volume, the volume-dependent cross-correlation coefficient reaches a limit value. This plateau value is controlled mainly by the large-scale behavior of the cross and direct variograms.The cross correlation can increase or decrease with volume support depending on the relative importance of long- and short-scale covariance structures. If the direct and cross variograms are proportional, there is no change in the cross correlation as the averaging volume changes. Our study shows that the volume-dependent cross-correlation coefficient is sensitive to the shape of the cross variogram and differences between the direct variograms of the well data and seismic data. 相似文献
110.