地震恢复重建规划区地质灾害特征及危险性评价

通过收集有关资料和实地勘察,描述并总结了四川省青川县板桥乡城建设用地地质灾害的发育特征。根据地质灾害点目前的稳定状态和潜在危害程度,定性评价了区内各地质灾害点的危险性。并基于各地质灾害点的危险程度,综合区内的地形地貌、地质条件和人为因素、气象水文条件,对青）ll县板桥乡地质灾害危险性进行了分区,为建设用地的规划设计提供了依据：     

基于分维数的土体裂隙表征单元体估算

由于干湿循环、剪切或其它作用,自然界土壤表面发育着大量裂隙。裂隙相互连接形成网络,裂隙网络是一个随机无序的系统,常规统计方法描述裂隙的分布特征存在很大的难度。网状土体裂隙一般具有分形特征,可以用分维数来进行描述。用数码相机拍摄土体表面的裂隙,将其转换成灰度图像,并结合分形理论,建立了摄影法测定土体裂隙分维数的方法,得到了土体裂隙的分维数。根据表征单元体的物理意义,建立了基于分维数估算表征单元体的方法,并对实例进行了分析。研究表明：分维数随裂隙密度,裂隙宽度和次一级裂隙发育程度的增大而增大;表征单元体与裂隙的密度均匀性和隙宽均匀性相关,基于分维数估算表征单元体的方法简便可行。     

Local responses in 2D assemblies of elliptical rods when subjected to biaxial shearing

Acta Geotechnica - This study explored the characteristics of local responses in 2D assemblies of elliptical particles when subjected to shearing. A biaxial shearing system was designed for this...     

古湖岸线的识别及其对砂体和油气的控制

古湖岸线是一定历史时期湖平面与古陆地的交线,即陆上与水下沉积的分界线。古湖岸线的识别过程就是一个沉积环境恢复的过程,识别标志包括地貌特征、特殊岩性、古生物特征、沉积构造、地球化学指标、地震反射特征以及沉积相变等多个方面。沉积盆地中古湖岸线对于砂体和油气的分布具有明显的控制作用,主要表现在：（１） 古湖岸线的类型控制了砂体的成因,古湖岸线的位置及迁移控制了砂体的分布和垂向叠加样式;（２） 古湖岸线控制了优质储集层的形成与发育,一般情况下水下砂体的储集层物性优于水上砂体; （３） 古湖岸线的频繁迁移为形成良好的储盖组合提供良好的沉积条件; （４） 古湖岸线附近是地层超覆油气藏、不整合遮挡油气藏及岩性油气藏发育的有利区带,并且油气藏沿古湖岸线呈现裙带状分布。     

玉米淀粉废水回收及处理研究

采用调节等电位点—超过滤组合技术对玉米淀粉废水的资源回收和处理进行研究,确定了最佳工艺参数。结果表明通过调节等电位点,可回收粗蛋白用作家禽饲料,同时废水中的CODcr、TSS和BOD5去除率分别可达48.8%、49.6%和27.2%以上,减轻了后续超过滤处理压力;通过超过滤进一步处理,出水COD、TSS和BOD去除率分别达91.3%、92.5%和95.1%。     

濮阳地区油田注水引起的重力场变化与地震活动性的关系

收集了1995—2007年中原油田濮阳地区各油田的注水开采等质量迁移资料,利用图示法研究发现油田注水与区域地震活动之间存在一定联系,并定量计算了油田注水引起的重力变化量。结合重力复测资料对油田注水引起的重力场变化和该地区地震之间的关系进行了初步研究,其注采作业引起的重力场变化在±0.1～10×10-8 m.s-2之间,并随着油田中心区域的距离而衰减。     

应力诱导各向异性介质中地震波的传播

主要讨论了应力变化如何影响各向异性介质中波速度的问题。推导了一般各向异性介质在初始应力下的Christoffel方程,得到介质中3种波的相速度和初始应力的关系表达式;通过实验数据验证了单轴应力能够诱导各向异性,当施加单轴应力时,速度在沿应力的方向增加最大,在垂直应力的方向增加最小,实验结果与理论推导一致;用Christoffel方程的数值解模拟在3种对称情况下的弹性各向异性介质中初始应力对波速度的影响。数值结果表明:初始应力对各向异性介质中波传播速度的影响,随着各向异性强度的增加而增大,而且速度越慢,影响越大。     

华北地区地震环境噪声特征研究

利用华北流动地震台阵观测的垂直分向连续波形数据, 通过计算功率谱密度和相应的概率密度函数, 对华北地区地震环境噪声特征进行了分析研究. 结果表明, 东部平原和沉积盆地2 Hz以上的高频环境噪声水平与全球新高噪声模型（NHNM）相近, 周期3——18 s的平均噪声水平低于NHNM和新低噪声模型（NLNM）的平均值; 山区及西部高原的高频噪声水平明显低于NHNM, 周期1——18 s的噪声水平大多明显低于NHNM和NLNM的平均值; 不同区域18 s以上周期的噪声水平差异相对较小. 流动地震台阵部分台站的环境噪声存在明显的昼夜变化, 个别台站噪声水平明显高于周边台站, 表明这些台站受人类活动干扰较大. 不同台站的噪声水平分析表明, 将台站布设在摆坑内, 能在一定程度上降低高频和低频段的噪声水平. 台站环境噪声特征的研究结果可为流动地震台阵观测数据质量的定量评估, 观测期间的台站优化调整等提供重要依据.      

Applicability of the Dual‐Domain Model to Nonaggregated Porous Media

More theoretical analysis is needed to investigate why a dual‐domain model often works better than the classical advection‐dispersion (AD) model in reproducing observed breakthrough curves for relatively homogeneous porous media, which do not contain distinct dual domains. Pore‐scale numerical experiments presented here reveal that hydrodynamics create preferential flow paths that occupy a small part of the domain but where most of the flow takes place. This creates a flow‐dependent configuration, where the total domain consists of a mobile and an immobile domain. Mass transfer limitations may result in nonequilibrium, or significant differences in concentration, between the apparent mobile and immobile zones. When the advection timescale is smaller than the diffusion timescale, the dual‐domain mass transfer (DDMT) model better captures the tailing in the breakthrough curve. Moreover, the model parameters (mobile porosity, mean solute velocity, dispersivity, and mass transfer coefficient) demonstrate nonlinear dependency on mean fluid velocity. The studied case also shows that when the Peclet number, Pe, is large enough, the mobile porosity approaches a constant, and the mass transfer coefficient can be approximated as proportional to mean fluid velocity. Based on detailed analysis at the pore scale, this paper provides a physical explanation why these model parameters vary in certain ways with Pe. In addition, to improve prediction in practical applications, we recommend conducting experiments for parameterization of the DDMT model at a velocity close to that of the relevant field sites, or over a range of velocities that may allow a better parameterization.     

Dynamic mechanisms controlling the topography of Longmenshan area

The Longmenshan fault, which defines the eastern edge of the Tibetan Plateau, is one of the steepest margins of the plateau with a sharp elevation drop of about 4 km over a distance less than 100 km across the Longmenshan fault. The mechanism which is responsible for controlling and maintaining the elevation difference is highly debated. Using multiple observations including seismic velocity model, Moho depth, effective elastic thickness of the lithosphere, we conducted a quantitative study for elucidating the contributions from crust and lithospheric mantle by an integrated analysis of lithospheric isostasy and flexure. It is shown that the topography of the Longmenshan fault is supported by both lithospheric isostasy and flexure statically, and lower crustal channel flow and mantle convection dynamically. Different mechanisms have different weights for contribution to the topography of the Songpan-Ganzi block and the Sichuan Basin. The static and dynamic support contribute roughly the same to the topographic difference of ~4 km between the two sides of the Longmenshan fault. The static topographic difference of ~2 km is mainly resulted from the lithospheric isostasy, while the dynamic one of ~2 km is contributed by the uprising of the accumulated material in the lower crust beneath the Songpan-Ganzi block and the downward drag force caused by the upper mantle convection under the Sichuan Basin. It is thus suggested that the lower crustal flow and upper mantle convection are dynamic forces which should be taken into account in the studies on the dynamics in the Longmenshan and surrounding regions.