The fractal geometry of flow paths in natural fractures in rock and the approach to percolation

The distributions of contact areas in single, natural fractures in quartz monzonite (Stripa granite) are found to have fractal dimensions which decrease fromD=2.00 to values nearD=1.96 as stress normal to the fractures is increased from 3 MPa up to 85 MPa. The effect of stress on fluid flow is studied in the same samples. Fluid transport through a fracture depends on two properties of the fracture void space geometry. the void aperture; and the tortuosity of the flow paths, determined through the distribution of contact area. Each of these quantities change under stress and contribute to changes observed in the flow rate. A general flow law is presented which separates these different effects. The effects of tortuosity on flow are largely governed by the proximity of the flow path distribution to a percolation threshold. A fractal model of correlated continuum percolation is presented which quantitatively reproduces the flow path geometries. The fractal dimension in this model is fit to the measured fractal dimensions of the flow systems to determine how far the flow systems are above the percolation threshold.     

An approach to mass movements in the Jiuzhaigou catchment

This paper presents a preliminary study of the main types, features, genesis, and countermeasures of mass movements in the Jiuzhaigou catchment, which is one of the most scenic regions in China. The main features are debris flows, rock-segment flows, landslides, and avalanches. Rough relief, fractured rocks, drifts, steep slopes, intensive rainstorms, and earthquakes produced their geneses. Countermeasures should include the integration of engineering and biological projects.     

Interpolation by regularized spline with tension: II. Application to terrain modeling and surface geometry analysis

A general approach to the computation of basic topographic parameters independent of the spatial distribution of given elevation data is developed. The approach is based on an interpolation function with regular first and second order derivatives and on application of basic principles of differential geometry. General equations for computation of profile, plan, and tangential curvatures are derived. A new algorithm for construction of slope curves is developed using a combined grid and vector approach. Resulting slope curves better fulfill the condition of orthogonality to contours than standard grid algorithms. Presented methods are applied to topographic analysis of a watershed in central Illinois.     

Frictional heat generation and seismic radiation in a foam rubber model of earthquakes

Results from a study of stick-slip particle motion at the interface between two stressed foam rubber blocks indicate that normal vibrations and interface separation are an important part of the stick-slip process in foam rubber. The dimension of the dynamic slip pulse is small compared to the dimension of the model (approximately 10 cm vs. 200 cm) consistent with the abrupt-locking slip pulse model ofBrune (1970, 1976), andHeaton (1990). A comparison of frictional heat generation between stable-sliding and stick-slip foam rubber models indicates a linear relation between the temperature increase on the fault surface (for a given distance of slip) and the driving shear force for the stable-sliding model, while for the stick-slip model there is essentially no variation in frictional heat generation with an increase in shear stress. We performed experiments to investigate the ratio of normal motion to shear motion at different levels of normal stress in the stick-slip foam rubber model. Preliminary result indicate that the normal component of the particle motion increases more rapidly with increasing normal stress than the shear component. The phenomenon of interface separation and normal vibrations may thus explain some of the most frustrating problems in earthquake mechanics, e.g., the heat flow paradox, the long-term weakness of major active faults, and anomalousP-wave radiation.     

四川省宁南县城后山泥石流激发雨强

根据宁南县城后山垂直剖面观测资料，对本区降雨的垂直变化及泥石流激发雨强作了探讨。当地暴雨泥石流发生所需的１０分钟雨强ｉ＿（１０ｍｉｎ）和前期降水量Ｐａ组合为：：ｉ＿（１０ｍｉｎ）≥１５ｍｍ∩Ｐａ≥５０ｍｍ，或ｉ＿（ｍｉｎ）≥１０ｍｍ∩Ｐａ≥６５ｍｍ，或ｉ＿（１０ｍｉｎ）≥５ｍｍ∩Ｐａ≥９０ｍｍ。超过上述各组合值就有可能暴发泥石流。     

贡嘎山区全新世冰川变化与泥石流发育的关系

贡嘎山区在全新世初期（１００００－７５００ａＢＰ），气候渐暖，冰川后退，泥石流发生频次剧增；中期（７５００－４０００ａＢＰ），出现高温气候，冰川强烈后退，沉积物则以冰水河流相为主；晚期（＜４０００ａＢＰ），气候转冷，出现新冰期。嗣后，气候转暖，但有三次明显的冰进过程；４００ａＢＰ前，气候再度转冷，出现小冰期。大量的泥石流点是出现在气候转暖、冰川退缩的初始阶段。     

微波等离子体炬原子发射光谱法测定铁和铝的研究

研究了低功率微波等离子体炬原子发射光谱法（ＭＰＴ－ＡＥＳ）对Ｆｅ，Ａｌ的测定。样品经气动雾化后，分别以流动注射与连续式两种方式引入ＭＰＴ。考察了用这两种进样方式时ＭＰＴ－ＡＥＳ的分析性能，证明低功率ＭＰＴ－ＡＥＳ具有良好的分析特性。     

开敞水域中航槽流场的数值模拟

建立了一个模拟开敞水域中航槽流场的平面二维数学模型.利用该模型计算得到的流速分布与袁美琦、李安中等人试验值相吻合,并计算了相当于天然情况下(各种水深、挖深比及航槽与水流的不同交角)的流场,得到了各种航槽与水流交角、不同挖深比的航槽流速折减系数变化规律图,及各种航槽与水流交角、不同挖深比的航槽中流向与航槽轴线交角的变化规律图,为开敞水域中航槽选线设计提供了依据.