Simplified approach for design of raft foundations against fault rupture. Part Ⅱ： soil-structure interaction

This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip （normal and thrust） fault rupture. The first two steps dealing with fault rupture propagation in the free-field were presented in the companion paper. This paper develops an approximate analytical method to analyze soil-foundation-structure interaction （SFSI）, involving two additional phenomena： （i） fault rupture diversion （Step 3）; and （ii） modification of the vertical displacement profile （Step 4）. For the first phenomenon （Step 3）, an approximate energy-based approach is developed to estimate the diversion of a fault rupture due to presence of a raft foundation. The normalized critical load for complete diversion is shown to be a function of soil strength, coefficient of earth pressure at rest, bedrock depth, and the horizontal position of the foundation relative to the outcropping fault rupture. For the second phenomenon （Step 4）, a heuristic approach is proposed, which ＂scans＂ through possible equilibrium positions to detect the one that best satisfies force and moment equilibrium. Thus, we account for the strong geometric nonlinearities that govern this interaction, such as uplifting and second order （P-△） effects. Comparisons with centrifuge-validated finite element analyses demonstrate the efficacy of the method. Its simplicity makes possible its utilization for preliminary design.     

Magnetic Influences of Cement Dust on Soil in Industrial Area and Its Environmental Implications

To monitor environmental implications of cement dust on soil in industrial area, magnetic parameters and mineral compositions were measured by the samples of the cement dust, cement factory dustfall, cement, coal ash, topsoil of green space in the factory and topsoil outside the factory. Results showed that the major magnetic minerals in the samples were magnetite, the magnetic mineral particle size of cement dust, dustfall, cement and coal ash was coarse Multi-Domian (MD) and Pseudo-Single-Domain (PSD). As topsoil of green space in the factory and topsoil outside the factory were polluted by cement dust, their magnetic properties had been obviously changed; the concentration of magnetic minerals elevated and particle size became coarser. The magnetic parameters (χ_fd,χ_ARM/χ,χ_ARM/SIRM) value can reflect the pollution level of the soil, the lower its value was, the more serious soil was polluted. X-ray diffraction results showed that the mineral compositions of the topsoil of green space in the factory and topsoil outside the factory were quartz and calcite, which were the same as cement dust. Magnetic parameters combination characteristics of topsoil can monitor the soil environmental changes in cement industry area.     

运动学涡度及其在湘东雁林寺韧性剪切带中的应用

自然界中的剪切带通常是由简单剪切(simple shear)和纯剪切(pure shear)叠加的一般剪切带(general shear)。运动学涡度(kinematic vorticity)的引入提供了一个定量表示两种剪切成分的工具。通过测量剪切带的运动学涡度,可以清楚的了解一般剪切带中究竟是简单剪切还是纯剪切占优势。本文将运动学涡度的基本理论和极摩尔圆法对雁林寺金矿所在的湘东雁林寺韧性剪切带中所表现的运动学涡度进行测量,得出该韧性剪切带的Wk值为0.6,指示其变形以纯剪切为主,且简单剪切作用应变速率比纯剪切作用的应变速率慢。本文从微观运动学层面揭示了湘东雁林寺韧性剪切带对于雁林寺金矿的形成具有重要的意义。     

关于地球化学数据处理方法的讨论-以大兴安岭喜桂图地区1/20万区域地球化学数据为例

针对地球化学数据中存在的离群数据点在地球化学图面上出现的等量线畸变或“牛眼点”现象,本文使用多种数据网格化插值方法和参数对比以消除“公牛眼”现象,结果表明,克里格、径向基本函数、改进的谢别德、最小曲率、移动平均等方法均不能较好地消除该现象。各种网格化算法编制的地球化学等量线图和交叉验证结果证明,以改进的指数距离幂倒数加权网格化方法效果最好,并且网格参数选择中以取样间距为网格间距,以2.5倍网格间距为搜索半径和幂指数因子的网格化参数既能消除等量线畸变现象,又能对原始数据进行较接近的表达。上述各种地球化学数据网格化插值方法的对比及结果可为地球化学数据处理中遇到同类问题提供信息。     

相位误差、位置误差和灰度误差三者关系及SAR原始图像像元不确定性

由于SAR遥感的独特优势，使它得到了广泛的应用。因此，对SAR图像的不确定性研究也越来越必要和迫切了。针对数据分析方法的不足，该文着重从机理的角度探讨SAR原始像元的不确定性。相位误差、位置误差和灰度误差三者关系、各种误差分类和综合以及这些误差对SAR原始像元不确定性作用等问题往往是困扰从机理角度对SAR图像不确定性研究的主要障碍，该文重点讨论这些问题。     

A coupled discrete element model for the simulation of soil and water flow through an orifice

Soil erosion around defective underground pipes can cause ground collapses and sinkholes in urban areas. Most of these soil erosion events are caused by fluidization of the surrounding soil with subsequent washing into defective sewer pipes. In this study, this soil erosion process is simplified as the gradual washout of sand particles mixed with water through an orifice. The discrete element method is used to simulate the large deformation behavior of the sand particles, and the Darcy fluid model is coupled with this approach to simulate fluid flow through porous sand media. A coupled 3D discrete element model is developed and implemented based on this scheme. To simulate previous experiments using this coupled model considering the current computing capacity, we incorporated a ‘supply layer’ to study the continuous erosion process. The coupled model can predict the erosion flow rates of sand and water and the shape of erosion void. Thus, the model can be used as an effective and efficient tool to investigate the soil erosion process around defective pipes. Copyright © 2017 John Wiley & Sons, Ltd.     

旅游景观生态系统格局研究方法探讨——以云南省丽江纳西族自治县为例

在旅游景观生态系统格局理论研究基础上,为反映功能异质性特征,从要素作用空间分异的角度,较为系统地建立了格局研究的方法体系。文章选择云南省丽江县进行了案例研究,结果表明:(1)方法的提出丰富了现有景观格局研究工作,结构与过程研究的结合,更符合旅游景观生态系统中以旅游者为主导的要素相互作用空间过程;(2)方法具有较高的应用价值,例如斑块范围研究能更好地反映旅游者的实际活动范围,为旅游目的地的旅游者管理与自然环境保护提供了更符合实际应用的空间依据。     

鸡西盆地构造演化及煤层气资源量概率分布

鸡西盆地是松辽盆地外围东部勘探的重要目标区之一。早白垩世发育有多套煤系地层, 且分布面积广, 储量丰富, 是重要的烃源岩。本文在研究鸡西盆地地质构造特征的基础上, 恢复了鸡D1井区沉降史。沉降史曲线反映出该盆地经历了早期的快速断陷沉降, 但其间发生过三次短期抬升与剥蚀。从下白垩统上部猴石沟组沉积开始, 盆地进入了相对稳定沉降时期。海浪组沉积之后, 本地区发生了较长时间(约28 Ma) 的抬升与剥蚀, 而这一时期是鸡西盆地演化史上一次主要的构造变动期, 是盆地基本构造格局的形成期。根据早期的强烈快速断陷阶段形成的煤系相关参数并运用蒙特卡罗法计算的煤层气资源量在0.1、0.5、0.9的概率下分别为81.7 ×1011 m3、5.36 ×1011 m3、2.41 ×1011 m3。     

Modelling landslides in unsaturated slopes subjected to rainfall infiltration using material point method

This paper presents a dynamic fully coupled formulation for saturated and unsaturated soils that undergo large deformations based on material point method. Governing equations are applied to porous material while considering it as a continuum in which the pores of the solid skeleton are filled with water and air. The accuracy of the developed method is tested with available experimental and numerical results. The developed method has been applied to investigate the failure and post‐failure behaviour of rapid landslides in unsaturated slopes subjected to rainfall infiltration using two different bedrock geometries that lie below the top soil. The models show different failure and post‐failure mechanisms depending on the bedrock geometry and highlight the negative effects of continuous rain infiltrations. Copyright © 2016 John Wiley & Sons, Ltd.