High slope stability of diversion power system intake of Jinchuan hydropower station

The excavated height of the left bank slope of the diversion power system intake in Jinchuan hydropower station is about 16o m. The stability and safety of the slope during construction and its operation/utilization become one of the most important geological engineering problems. At the same time, it is also crucial to select a safe and economic excavation gradient for the construction. We studied the problem of how to select a safe and economic slope ratio by analyzing the geological condition of the high slope, including the lithology, slope structure, structural surface and their combinations, rock weathering and unloading, hydrology, and the natural gradient. The study results showed that the use of an excavation gradient larger than the gradient observed during site investigation and the gradient recommended in standards and field practice manuals is feasible. Then, we used the finite element method and rigid limit equilibrium method to evaluate the stability of the excavation slope under natural, rainstorm and earthquake conditions. The calculated results showed that the excavated slope only has limited failure, but its stability is greatly satisfactory. The research findings can be useful in excavation and slope stabilization projects.     

多因素组合影响阶段矿柱上采顶板临界厚度研究

采用散体充填法的矿山,由于充填体无法直接暴露,阶段矿柱回采临界厚度的保留成为残矿回收的突出难题。基于传统弹性梁理论,结合实际情况,将阶段矿柱简化为均布载荷下两端固定的弹性梁力学模型,推导了其弹性应力解,揭示了 是阶段矿柱上采过程的第1破坏应力。理论分析表明：影响矿柱上采顶板临界厚度的主要因素为：散体载荷、回采跨度和岩体抗拉强度。利用FLAC3D完成了多因素组合影响阶段矿柱上采过程数值模拟正交试验,分析了单一影响因素与顶板临界厚度的关系,利用多元非线性回归的数学方法,建立了上采过程三因素组合影响下阶段矿柱临界厚度数学预测公式。最终,实现了散体介质下阶段矿柱上采临界厚度的预测。结合凤凰山铜矿-240 m阶段矿柱回采实际,表明了该预测公式的适用性。     

CCD˫�������ǵ����Ƽ�Ӧ��

?????????????????????????????????????????????????????????????????λ??????????С????н?????????????????????????????Ч?????á?     

微动面波的介质响应和H/V谱特征研究

目前,微动面波信息研究的主要方法是对面波中的Rayleigh波成分进行相关性分析.为了充分有效的利用面波信息和提高识别的准确度,本文基于微动面波H/V谱的基本原理,通过对给定模型的数值计算,得到了微动面波的介质响应曲线和H/V谱,分析了面波中Rayleigh波和Love波多模式波的介质响应和H/V谱特征.结果表明微动面波的介质响应特征与地层界面具有一定的对应关系,且在H/V谱中Rayleigh波和Love波的主频具有一致性,Love波的利用对H/V谱具有增强作用,文中也指出了H/V谱法在高频应用领域中有待进一步解决的问题.由于该方法使用的是地微动噪声中的面波信息,不需要专门的震源,因此具有经济快捷、应用范围广泛等优点,将可能成为一种新的有很好应用前景的地球物理勘探方法.     

辽中凹陷北部湖底扇沉积模式及地震响应特征

综合利用辽中凹陷钻井和地球物理资料进行井—震标定、地震地层学解释和地震相分析.在东营组二段(简称东二段)沉积时期,该区分布多个NE向古辽河水系发育的三角洲沉积体系,存在前缘相带砂体整体滑塌并近距离搬运而形成的湖底扇沉积.湖底扇具有期次多、数量大和横向展布范围广等特点,不同沉积亚相(内扇、中扇、外扇)具有敏感的地震响应特征.分析锦州20构造测井资料的岩—电组合特征,探讨湖底扇形成条件,建立湖底扇的沉积模式,识别湖底扇沉积各亚相的地震响应特征;基于井—震标定技术,利用地震相干体和地震属性方法,研究2期湖底扇沉积横向展布特征,精细刻画有良好油气发现的Ⅱ期湖底扇中扇亚相储层发育边界.结果表明:应用湖底扇沉积模式和地震响应特征,在辽中凹陷北部东二段发现多个湖底扇沉积体,是有利的岩性油气勘探目标,对渤海海域岩性油气藏勘探具有指导意义.     

���ջ��ز���ʼ��λƫ��仯���Է���

???????????????????λ??????????????????????????????????±?????????·???????????λ????????????????????λ???????????λ???????????????????????????????????????????????λ????????????????????????????????????????????????仯?????     

白榆、新疆杨液流动态比较研究

运用Granier热扩散式探针(TDP)法对宁夏河东沙地主要乔木树种白榆（Ulmus pumila）和新疆杨（Populus alba）夏初边材液流变化规律进行连续观测。利用自动气象站对周围气象因子如太阳辐射（Rs）、空气温度（Ta）、空气相对湿度（RH）和风速（Ws）进行同步观测,并对气象因子与白榆、新疆杨边材液流通量(Fs)的相关性进行分析。结果表明：①白榆、新疆杨边材液流速率（Vs）变化规律存在显著差异,白榆Vs主体表现为窄小双峰型,新疆杨Vs主体表现为宽峰波动型;白榆日间液流启动时间较新疆杨提前0.0~0.8 h,峰值出现时间推迟0.0~2.0 h,峰值持续时间较新疆杨缩短2.5~6.7 h,液流消退时间提前0.0~2.5 h。②白榆边材液流通量(Fs)仅为0.50 kg·h-1,而新疆杨高达1.25 kg·h-1,为白榆的2.5倍;白榆日耗水量（W）在8.81~17.73 kg·d-1之间,而新疆杨W在22.82~34.06 kg·d-1之间。③白榆、新疆杨在夜间保持一定的液流量以补充白天所耗水分,夜间水分补充量对各自日耗水量的贡献相近,为8%左右。④白榆、新疆杨Fs与气象因子关系密切,但气象因子的作用过程表现复杂。复相关分析表明：白榆、新疆杨Fs与Rs、Ta、Ws之间呈极显著正相关,与相对湿度RH呈极显著负相关,按相关程度排序为：Rs>RH>Ta>Ws。     

Large‐scale seismic tests of tall concrete bridge columns with precast segmental construction

Past experimental studies have shown that existing precast segmental concrete bridge columns possess unsatisfactory hysteretic energy dissipation capacity, which is an undesirable feature for applications in seismic regions. In this research, we propose new methods of precast segment construction for tall concrete bridge columns to enhance the columns' hysteretic energy dissipation capacity and lateral strength. This is accomplished by adding bonded mild steel reinforcing bars across the segment joints, strengthening the joint at the base of the column and increasing the height of the base segment (hinge segment). Four large‐scale column specimens were fabricated and tested with lateral cyclic loading in the laboratory. Each specimen consisted of a foundation and 9 or 10 precast column segments. Test results of specimens with the proposed design concepts showed ductile behavior and satisfactory hysteretic energy dissipation capacity. In addition to the experimental study, an analytical study using the finite element method was conducted to understand the bond conditions, strain contours and deformation patterns of the specimens tested. Good agreement was found between the experimental observations and the results of the calibrated analytical study. Copyright © 2008 John Wiley & Sons, Ltd.     

Fossil gastropods from the MGS3 stratigraphic segment in the Salawusu River Valley and their climatic and environmental implications

Contemporaneous with MIS3, the MGS3 segment of the Milanggouwan stratigraphic section in the Salawusu River Valley, Mu Us Desert, China contains fossil gastropods (terrestrial and freshwater snails) in strata 33LS, 35LS, 37FL and 39LS. Examination of these fossils revealed 11 species belonging to 8 families and 10 genera. They can be classified as: (1) assemblage of Gyraulus and Galba mainly consisting of Gyraulus convexiusculus, Gyraulus sibiricus, Galba pervia and Galba superegra Gredler, etc. (2) assemblage of Vallonia mainly consisting of terrestrial snails, such as Vallonia patens, Pupilla muscorum and Discus paupe, etc. Based on the dating results, and the living habits, living conditions, and geographic distribution of their extant species, we suggest that: the ages of 33LS, 35LS, 37FL, and 39LS are 26000, 29000, 33000 and 38000 a, respectively, corresponding well to the interstadial period in GRIP 4, 5, 6 and 10 in terms of chronology and climatic characters; 33LS, 35LS and 39LS represent very warm-humid periods, while 37FL represents a less warm-humid period; the four periods of climatic fluctuations recorded in MGS3 were related to the strong impact of the summer monsoon in East Asia in Mu Us Desert of China during the interstadial of MIS3 on a global climatic background.