基于地下水流场和含水介质分析的敦煌月牙泉成因研究

在分析月牙泉多年动态变化趋势的基础上,依据最新水文地质勘探资料和编绘的月牙泉周围年丰水期、枯水期地下水等水位线图,从地下水流场和含水介质的角度分析研究了月牙泉形成原因。月牙泉上游地下水基本呈自西南向东北径流,在地势低洼的沙漠丘间地带出露形成月牙泉;地下水补给来源为上游党河右岸黑山咀子东侧浅层地下潜水的侧向径流,黑山咀子至月牙泉之间的地下水水力坡度在丰水期为4. 813‰,枯水期为 4. 622‰;月牙泉泉水与周边地下水是统一的水力系统;月牙泉附近含水层是党河冲洪积层的连续的过渡关系,泉水出露形成是含水层与特殊地形地貌结合的产物。     

川中红层水理特性及对无砟轨道变形影响机制分析

针对川中红层易引起无砟轨道上拱变形的问题,开展了川中红层泥岩膨胀特性、水理特性试验研究,在掌握川中红层泥岩膨胀、渗透特性的基础上,结合实际工程进行上拱变形病害区水文环境调查、原位抽水试验以及现场监测,揭示了川中红层的赋存水环境及其运移特征,即川中红层为相对隔水层,所夹节理裂隙及与砂岩界面是其与外界水力联系的主要形式,水力联系通道都是局部、随机分布的,且与自然降雨联系不紧密,赋存水多以透镜体形式存在。在上述特征地层中深挖无砟轨道路基,形成卸荷红层风化裂隙带的同时,改变了原有随机分布的水力联系通道,使得天然状态下相对隔水基底弱风化泥岩与外界建立新的水力联系,膨胀性红层泥岩遇水后膨胀是导致无砟轨道路基持续上拱的内在机制。     

构造-流体耦合有限元模拟:以石英脉型钨矿为例

热液矿床成矿作用动力学过程涉及多时空高度耦合的物理和化学过程。数值模拟是研究这一复杂动力学过程的重要而有效的工具之一,也可在找矿预测等方面发挥重要作用。以南岭地区石英脉钨矿床为例,利用计算机求解控制构造-流体的物理和化学方程,定量揭示成矿热液聚焦流动与"五层楼"成矿的对应关系,正演高压成矿流体致使围岩发生水力破裂及其成矿效应。模拟结果与石英脉型钨矿床的构造地球化学特征相符。     

雪峰山深孔水压致裂地应力测量及其意义

利用最新研制的深孔水压致裂地应力测量设备在雪峰山2000 m科钻先导孔内开展了原地应力测量,在孔深170~2021 m范围内获得了16个测段的有效地应力测量数据,是国内首次利用水压致裂法获得的孔深超过2000 m深度的原地应力测量成果。测量结果表明,地应力随孔深增加而逐渐加大,对实测数据进行线性回归,得到最大和最小水平主应力随深度变化的关系分别为:S_H=0.03328H+5.25408,S_h=0.0203H+4.5662,在孔深2021 m深度,其实测值分别为66.31 MPa和43.33 MPa。基于实测数据,结合钻孔成像测试和井温测试结果,对测点应力状态进行了综合分析。在170~800 m深度范围,三向主应力关系为S_H > S_h > S_v,有利于逆断层活动;孔深1000~2021 m表现为S_H > S_v > S_h,表明该区域深部应力结构属于走滑型。最大水平主应力方向为北西-北西西方向。基于实测地应力数据及莫尔-库伦破裂准则,对测区附近断层活动性进行了分析讨论,认为该区域断层处于稳定状态。      

Resistivity saturation in liquid iron–light-element alloys at conditions of planetary cores from first principles computations

We present a comprehensive analysis of electrical resistivity for liquid Fe–Si, Fe–S, and Fe–O alloys from first principles computations, covering the pressure/temperature conditions and major light element candidates inside the cores of terrestrial planets. By fitting optical conductivity with the Drude formula, we explicitly calculate the effective electron mean free path, and show that it becomes comparable to the interatomic distance for high densities and Si/S concentrations (Ioffe–Regel criterion). In approaching the Ioffe–Regel criterion, the temperature coefficient of resistivity decreases with compression for all compositions, eventually vanishes (Fe–Si), or even changes sign (Fe–S). Differences in resistivity and the degree of saturation between the iron alloys studied are explained in terms of iron–light element coordination numbers and their density dependence. Due to competing temperature and pressure effects, resistivity profiles along proposed core adiabats exhibit a small negative pressure gradient.     

Magma chamber growth models in the upper crust: A review of the hydraulic and inertial constraints

Finite volumes of magma moving in confinement, store hydraulic potential energy for the generation,control and transmission of power. The Pascal's principle in a hydraulic jack arrangement is used to model the vertical and lateral growth of sills. The small input piston of the hydraulic jack is equivalent to the feeder dike, the upper large expansible piston equivalent to the magmatic chamber and the inertial force of the magma in the dike is the input force. This arrangement is particularly relevant to the case of sills expanding with blunt tips, for which rapid fracture propagation is inhibited. Hydraulic models concur with experimental data that show that lateral expansion of magma into a sill is promoted when the vertical ascent of magma through a feeder dike reaches the bottom contact with an overlying, flat rigid-layer. At this point, the magma is forced to decelerate, triggering a pressure wave through the conduit caused by the continued ascent of magma further down(fluid-hammer effect). This pressure wave can provide overpressure enough to trigger the initial hydraulic lateral expansion of magma into an incipient sill, and still have enough input inertial force left to continue feeding the hydraulic system. The lateral expansion underneath the strong impeding layer, causes an area increase and thus, further hydraulic amplification of the input inertial force on the sides and roof of the incipient sill, triggering further expansion in a self-reinforcing process. Initially, the lateral pressure increase is larger than that in the roof allowing the sill to expand. However, expansion eventually increases the total integrated force on the roof allowing its uplift into either a laccolith, if the roof preserves continuity, or into a piston bounded by a circular set of fractures. Hydraulic models for shallow magmatic chambers, also suggest that laccolith-like intrusions require the existence of a self-supported chamber roof. In contrast, if the roof of magmatic chambers loses the self-supporting capacity, lopoliths and calderas should be expected for more or less dense magmas, respectively, owing to the growing influence of the density contrast between the host rock and the magma.     

DISCONTINUOUS FLOW OF TURBID DENSITY CURRENTS I. CHANNEL EXPANSION AND CONTRACTION

Laboratory experiments on turbid density currents were conducted to observe the flow features of these currents with abrupt contracted and expanded reaches. Experimental data were used to determine water entrainment coefficients for both channel expansion and contraction. Expressions for turbid density currents with water entrainment coefficients in abrupt contracted and expanded reaches were derived, and compared with experimental data.     

大兴安岭森林覆盖区金矿土壤离子电导率异常特征离子成份的研究及找矿预测

为了解森林覆盖区金矿体土壤离子电导率异常特征,探讨金矿体土壤离子电导率成份是由哪些种类离子组成,弄清不同种类离子的含量变化关系对电导率的贡献大小,为解释金矿土壤离子电导率异常的形成机制提供理论依据.通过在大兴安岭森林覆盖区虎拉林金矿的研究:(1)在已知的金矿体上测出了清晰的电导率异常,异常呈典型双峰形态"兔耳"状或"锯齿"状, 异常垂直指示金矿体的赋存位置.(2)弄清了金矿体组成土壤离子电导率异常的离子成份特征,其成份主要是HCO-3、SO-24、Ca2 、Cl-、K 、Na 、F-、Mg2 、Mn2 等一套水可溶性离子,经过相关分析得出金矿电导率异常与各水可溶性离子的相关系数是HCO-3＞Ca2 ＞SO2-4＞Cl-＞K ＞F-＞Na ＞Mg2 ＞Mn2 .(3)在未知区的找矿预测中找到3个具有成矿远景的离子电导率异常.     

EH4连续电导率测量在宝兴厂矿区的应用

宝兴厂矿区是一个与喜马拉雅期富碱斑岩有关的多金属成矿集中区,具有斑岩型矿床特征,岩体与围岩接触带、近东西向构造裂隙带是主要控矿构造,奥陶系地层与斑岩体具有明显的物性差异,利用EH4连续电导率物探测量能够较好地反映出隐伏的斑岩体与围岩接触带部位.对该区深部地质找矿具有指导作用.     

土体内在结构对热导率计算模型的影响研究

为得到适用于土体的热导率模型,利用软件将土样扫描电镜图片（反映土体的真实结构）二值化,采用瞬态传热分析方法对土体进行二维传热分析,通过ANSYS模拟土体并分析得出土体热导率。并且将数值分析结果与实测结果进行对比,发现两者间误差较小,说明该方法能较精确地得到土体热导率,为土体热导率理论模型的建立提供了一种新方法。在此基础上,对粉砂、粉土及粉质粘土的热导率进行研究,发现土体热导率随孔隙率的增大而减小,粉砂热导率的减小速率最大,其次为粉土,最小为粉质粘土。