粗粒料湿化变形数值模拟研究

粗粒料湿化变形特性对土石坝静力稳定有着显著影响。目前开展的三轴试验和直剪试验研究,一般只能进行干样和饱和样的试验,而对于非饱和情况研究较少。基于粗粒料不同围压下湿化变形试验研究成果开展数值模拟研究,结果表明：湿化变形的影响可以通过改变细观剪切模量和细观摩擦系数来实现;随着颗粒破碎随饱和度和围压的增加,湿化后粗粒料的强度低、内聚力降低,但摩擦角变化不大。     

基于正交设计的麻柳林滑坡稳定性敏感分析

以麻柳林滑坡为例,选取了内摩擦角、粘聚力、渗透系数、浸没率、库水位下降速率及降雨量等6个因素进行了正交试验,采用极差分析法进行了稳定性敏感分析.结果表明,滑坡稳定性及其变化率主要由内因决定,库水和降雨对其影响较小.滑坡稳定性对内摩擦角最敏感,其次依次为渗透系数、粘聚力和浸没率.滑坡初始稳定性主要由内摩擦角和粘聚力决定.滑坡稳定性随浸没率的降低而逐步增加,但增幅较小;渗透系数对滑坡稳定系数变化率的影响最大,并存在临界值K_0,渗透系数大于K_0时,滑坡稳定性随渗透系数的增加而增加,渗透系数小于K_0时,滑坡稳定性随渗透系数的降低而降低.     

土石坝振动台模型试验颗粒流数值模拟分析

目前一般采用振动台试验、离心振动台试验和有限元动力分析来获得土石坝在设计地震荷载作用下的形态和抗震性能。本文结合孔宪京等的土石坝振动台试验结果开展了颗粒流细观数值模拟研究,克服了传统连续介质力学的宏观连续性假设,形象而直观地表现出坝体在动力荷载作用下的破坏特征。数值模拟规律与振动台试验规律基本一致。同时还分析了坝体颗粒粘结强度和地震峰值加速度变化对坝体破坏特征的影响。数值结果表明,当颗粒间粘结强度较低时,表现为坝体表面颗粒的滑动破坏,粘结强度稍大时,会出现局部的小块颗粒团整体滑动破坏;随着峰值加速度的增大,坝顶沉降量在增大,坝体破坏特征不变。     

金沙江河谷巧家段地下水化学特征

金沙江河谷巧家段地形切割强烈,最大相对高差可达2 719 m,水文地质条件差异大,河谷区内泉水出露众多。对河谷区内38组泉水水化学组分进行分析的结果表明:地下水化学类型较简单,主要为HCO3- Ca、HCO3- Ca?Mg、HCO3- Mg?Ca型;地下水溶解性总固体(TDS)浓度变化较大,总体上TDS浓度自河谷斜坡补给-径流区至谷底排泄区,具有逐步增高的趋势;孔隙水TDS浓度明显高于岩溶水;地下水宏量组分HCO3-、Ca2+、Mg2+、SO42-与TDS具有正相关关系。据水化学组分变化分析谷底第四系地层中出露大泉的形成条件,其为孔隙水与岩溶水相混合形成。      

滇东南岩溶区找水打井经验——以云南省广南县珠琳地区为例

以1996-2012年期间抗旱打井实例,总结了找水技术方法、勘查工作流程,提出了滇东南高原斜坡地带岩溶区找水要点:分水岭弱径流带,主要目标是在古溶蚀台面上接近区域分水岭的地段、规模较大的溶蚀洼地中的扬起端寻找浅层岩溶水;缓坡区较强径流带,主要目标是寻找面积较大、产状较平缓的悬托弱透水层之上的滞水型岩溶水;斜坡区强径流带,主要应寻找暗河天窗、竖井中的岩溶水。确定井位应遵循区域调查分析+井位附近详细调查分析的工作程序,必要时配合开展物探准确定位;不宜在排泄区、强径流区、峰丛洼地区、大泉、地下河附近、负地形最低部位布井,物探成果应用须与水文地质调查成果紧密结合。      

Water-inrush mechanism research mining above karst confined aquifer and applications in North China coalmines

Karst water poses great menace to vast and extensive coal-bearing region in China. The large water bodies which are highly pressurized have caused appalling disasters. This study takes example from the North China coal-bearing region and introduces karst aquifer distribution. It points out the major contributors to karst water burst and its relation with bottom plate deformation under mining activities. The analysis of criteria to determine karst water burst focuses on two elements (water burst coefficient and critical water burst index) and their positive application in Huaibei Luling coalmine, North China coal-bearing region. All achievements can be of reference to other coal-producing countries which are confronted with karst water hazards.     

Distribution and enrichment evaluation of heavy metals in Mejillones Bay (23 degrees S), Northern Chile: geochemical and statistical approach

A suite of 36 surface sediment samples, taken between 10 and 100 m water depth in Mejillones Bay (Northern Chile), were analyzed for mineralogy, grain size, total organic carbon, Al, and heavy metal content (Cd, Zn, Ni, Mn, V, Mo). Quartz and feldspars were the main lithogenic minerals and carbonate the predominant biogenic mineral. Sediments were fine sands in the shallow zone and organic silt in the deeper zone. Enrichment Factor and Factor Analysis approach showed that the presence of Mn in the marine sediment of Mejillones is due to a partial influence of continental input, while all other metals are not supported by lithogenic debris. Although all metals showed high concentrations in the marine sediment of Mejillones Bay, comparison between metal concentration in surface sediments and preindustrial levels in this bay, show that present values agree with natural levels.     

Statistical analysis in classification of bituminous coal

Hundreds of samples and 17 variables collected from coalfields of major coal-bearing strata over China except for Tibet and Taiwan, were used in this study. The dry, ash-free basis volatile matter (V ^r) and caking index (G _(RI)) were chosen by means of correlation analysis and stepwise discriminatory analysis as major indices of a new classification. By means of the optimum section, the boundary value of the axis of ordinate (G _(RI)) and axis of abscissas (V ^r) can be determined in the classification system. Thus, aV ^r –G _(RI) classification scheme diagram was formed and bituminous coal was divided into nine classes. Use of correspondence analysis reduced dimensions of sample-expressive space without losing initial information. The trend on the factor surface of samples shows that the classification obtained from correspondence analysis conforms to theV ^r –G _(RI) classification result and further verified the dependability of classification by two indices. At the same time, a certain relationship between the properties of a great variety of coal and their attributes can be explained. Hence, bituminous coal classification becomes more scientific, reasonable, and practical than before.     

Blast-resistant Analysis for a Tunnel Passing Beneath Taipei Shongsan Airport–a Parametric Study

This paper covers the blast-resistant analysis for a tunnel passing beneath Taipei Shongsan airport. It briefly discusses the overall analysis process to obtain the maximum lining thrust caused by a bomb explosion for use in the structural lining design. Because there have not been any established common standards or practices governing the design of such a structure, a series of parametric studies have been carried out in order to evaluate the significance and sensitivity of several parameters on the lining thrust. The parameters evaluated are: intensity of blast loading, size of crater, dynamic undrained shear strength, dynamic Young’s modulus, and soil-damping ratio. It was concluded that a designer should adopt dynamic soil parameters, obtained from good ground investigation and soil testing, as favorable dynamic soil properties can result in a more economical analysis. For parameters (e.g. bomb type) that are beyond the control of the designer, an additional protective layer over the tunnel structure may be considered in order to minimize the impact of the explosion, instead of designing a more costly rigid structure.     

Impact of land-use change on soil properties in a typical karst agricultural region of Southwest China: a case study of Xiaojiang watershed, Yunnan

Xiaojiang watershed is a typical karst agricultural region of Yunan Province, China. A case study of land-use changes documents changes of soil properties from 1982 to 2003. The results are as follows: (1) The total land use transformed covers 610.12 km², of which land use changed from unused land into cultivated land and forestland, and forestland into cultivated land during the past 20 years in Xiaojiang watershed. (2) The rapid growth of population and economic development were the main driving forces of cultivated land increase. (3) Soil properties showed modification owing to different land-use changes. The contents of the soil organic matter, total nitrogen, and total phosphorus in 2003 were significantly lower than that in 1982 after the forestland and unused land were transformed into the cultivated land, but the soil pH increased significantly in 2003. Organic matter, total nitrogen, and total phosphorus for shorter-time reforestation land declined, but the pH increased. Soil properties have improved significantly after cropland was transformed into orchard land. The organic matter, total nitrogen, total phosphorus, available nitrogen, and available phosphorus declined significantly, but pH increased significantly after rock desertification.