基质吸力变化引起的体积应变研究

与降雨有关的边坡表层变形位移,其根源是基质吸力降低引起的非饱和土体积应变。利用某滑坡体的原状样及其重塑样,分别在100kPa、200kPa围压作用下,采用单纯增加基质吸力的应力路径,对基质吸力引起的体积应变,进行试验测试。结果显示: (1)试样的体应变,随基质吸力的增大,单调增大,服从对数函数关系;(2)围压由100kPa增加到200kPa的试样体积模量,随基质吸力的增大,单调增大,服从幂函数关系;(3)与基质吸力有关的体积变化系数,随基质吸力的增大,单调减小,服从幂函数关系;并且当基质吸力大于200kPa以后,随基质吸力增大,体积变化系数接近于常数,约为0.0059左右。在此基础上,本文针对这种由单纯基质吸力变化引起的非饱和土体积应变规律及机理,进行了探讨。     

星际分子正—NH3和He的超精细跃迁碰撞截面和速率系数的理论计算

本文采用Ｒ矩阵传播方法，通过求解ＣＳ近似下的耦合方程，计算了星际分子云条件下正－ＮＨ３分子和Ｈｅ碰撞的超精细跃迁碰撞截面和速率系数，为研究天体的信息提供需用的基础数据。     

日食一厄尔尼诺系数及其应用

通过比较本世纪以来的厄尔尼诺年和日食资料,发现了高纬（包括极区）日食与厄尔尼诺年之间存在着一定的因果关系。通过定义年日食一厄尔厄诺系数Ｒ１和累积日食一厄尔尼诺系数Ｒ２后,可以发现当某年的Ｒ１≥９或Ｒ２≥１０．５级时,则当年必为厄尔尼诺年,反之亦然．本文还提出了日食诱发厄尔尼诺现象的热一动力机制,并预测２０００年将是一个强厄尔尼诺年．     

弹性波在离散介质中传播的贝塞尔函数解Ⅰ

对弹性波在离散介质中的传播问题进行了新的探索研究,本文用贝塞尔函数的线性组合构造了弹性波在非均匀离散介质中传播解。借助于贝塞尔函数的良好性质,其研究结果可用于地震波传播问题的研究。     

地球化学屏障中添加剂的选择研究

设置一系列加有不同添加剂的地球化学屏障,利用静态平衡实验,并与未加添加剂的空白实验对比,分析其对Ｕ,Ｃｏ,Ｓｒ的阻滞性能;并通过计算Ｋｄ值,对屏障的综合阻滞性能进行分析,选出恰当的添加剂。结果表明：ＮａＳ２作碱性－还原添加剂,利于核素的化学沉淀反应,而且Ｋｄ值显著地增加,屏障对Ｕ,Ｃｏ,Ｓｒ的阻滞性能最好。     

Effect of riparian land use on environmental conditions and riparian vegetation in the east African highland streams

Agricultural land use is expanding and at an accelerated rate. In Ethiopia, most of this expansion has occurred in highland areas and involve deforestation of natural riparian vegetation. However, the impacts on the water quality of streams are poorly understood, especially with regard to the influence of land use patterns on highland streams. In this study, we investigated the effects of land use modifications on the water quality and riparian condition of highland streams and examined whether the preservation of riparian vegetation would help mitigate the negative impacts of intensive agriculture practices. Our results show significant differences in the water quality of streams with different land use. Several parameters commonly used to indicate water quality, such as the concentrations of orthophosphate, turbidity, and suspended solids were significantly higher in the agricultural streams than in the forest stream. The preservation of riparian vegetation in the surrounding highland streams was associated with overall better riparian condition, floristic quality, and water quality such as lower turbidity, total suspended solids, orthophosphate, and higher dissolved oxygen. We conclude, that increases in vegetation cover improved riparian condition and water quality relative to other non-vegetated areas. Therefore, we strongly recommend the preservation of riparian vegetation in tropical highland streams surrounded by intensive agriculture. More studies on the effects of best management practices in areas dominated by agriculture can greatly improve our capacity to prevent the degradation of water quality in tropical highland streams of Africa.     

基于GIS和洛伦兹曲线的辽宁省海岛空间分布特征探析

为合理开发利用和保护辽宁海岛资源,优化海岛产业结构和布局,以辽宁纳入中国海域海岛标准名录的633个海岛为研究对象,在对其地理坐标、陆域面积等基础数据进行数理统计的基础上,通过GIS的空间分析和绘制洛伦兹曲线、计算基尼系数,对辽宁海岛的空间分布特征进行了分析与研究。结果表明:辽宁海岛属集聚型分布类型,在空间上呈组团与带状分布,按聚集程度来看,形成了黄海北部长山群岛集聚区、辽东半岛南部浅海集聚带与辽东湾西部浅海集聚带三个区域;约60%的海岛处在离大陆岸线直线距离在10 km以内的范围内,近陆程度高;海岛陆域面积分布不均衡,基尼系数达0.9。     

山西流体观测井水位与气压相关性分析

分析了山西省流体观测井水位动态特征,利用高阶差分、回归分析方法计算了2008年山西省各观测井水位与气压相关系数,得到了气压系数的背景值,进而对气压干扰因素进行定量化的排除,并对各井的气压系数进行对比分析。结果表明,不同的观测井孔水位受气压影响程度不同,对于某一个观测井孔而言,气压系数及相关系数的变化是有一定规律的。     

Application of the Dynamic Cone Penetrometer (DCP) for determination of the engineering parameters of sandy soils

Determination of the in situ engineering properties of foundation materials has always been a challenge for geotechnical engineers and, thus, several methods have been developed so far. Dynamic Cone Penetration (DCP) test is one of the most versatile amongst them. In the present research, a light weight simple DCP device was developed and used for evaluation of the engineering properties of sandy soils in laboratory conditions. The device consisted of an 8-kg hammer that drops over a height of 575 mm, and drives a 60° cone tip with 20 mm base diameter into the ground. To control the validation of the results, laboratory direct shear and plate load tests were used as reference tests. The soil sample was a poorly graded sandy soil (SP) taken from alluvial deposits of the Tehran plain. All DCP tests and PLTs were undertaken on compacted soil in a mould with 700 mm diameter and 700 mm height. Based on the results of the experiments, the relationships between Dynamic Penetration Index (DPI), relative density (D_r), modulus of elasticity (E), shear modulus (G), modulus of subgrade reaction (K_S), and the friction angle of the soil were obtained with a high coefficient of determination (> 90%). The repeatability of the test results was also evaluated by calculating the coefficient of variations (C_v), which was less than 30% for all tests.     

井水位振荡试验及其结果

通过鲁04井的频率特性试验,求出了该井含水层系统的频率特性参数,固有振动周期为40.59s,阻尼系数为0.0362s-1。并且计算出鲁04井含水层的导水系数为1.8×10-3m2/s。利用这些结果解释了鲁04井对地震波响应比珍珠泉井差的原因