基于颗粒流的土质边坡失稳机理

为研究降雨工况下诱发土质边坡失稳过程及破坏机理,以泸州市古蔺县竹林沟滑坡为依托,通过PFC2D双轴压缩试验对滑坡体饱和状态下的强度参数进行标定,确定滑坡细观参数与宏观参数的内在联系,并引入接触黏结模型,对其破坏过程特征进行模拟研究,并对滑坡关键位置处的速度、孔隙率以及位移进行实时监测.计算结果表明:滑坡破坏的过程为:初期整体蠕滑变形,随着变形的发展,滑坡体向坡前临空方向发生剪切蠕变,后缘产生由坡面向深部发展的张拉裂缝,随着潜在滑面贯通,滑坡失稳破坏;通过监测不同位置的速度发现,0～10 s为加速阶段,坡体最大速度达到约14 m/s,最大颗粒速度达到约20 m/s,15～25 s坡体速度开始下降,滑坡最大位移约600 m,整体位移约450 m,并于25 s左右坡体停止滑动.通过对竹林沟滑坡的数值模拟,采用离散元颗粒流的方法去研究滑坡的运动过程有较好的应用性,也能为同类型滑坡的防灾减灾提供较好的参考意义.     

考虑河床泥沙淤积的滑坡涌浪数值模拟

采用RNG k-ε紊流模型与VOF方法对散粒体滑坡涌浪进行数值模拟。通过与已有试验结果对比分析,发现数值模拟得到的滑坡体水下初始堆积形态、首浪高度与试验结果吻合度较好。目前针对河床泥沙淤积下的滑坡涌浪研究较少,基于此,本文建立了不同淤泥厚度及颗粒直径下滑坡涌浪的三维数值模型,分析了滑坡入水后涌浪高度、水位空间分布及泥沙流态变化。结果表明：初始涌浪高度随淤泥厚度增加先减小后增大,随颗粒直径增大而增大。     

泾阳南塬黄土滑坡冲击阶地易侵蚀层过程模拟

为探讨泾阳南塬地区黄土滑坡的高速远程的运动特征以及在运动过程中对阶地易侵蚀基层破坏迹象的产生机理。以泾阳南塬西庙店滑坡为研究对象,通过野外调查、勘探查明其运动特征,运用颗粒流离散元法模拟滑坡运动过程、机理。结果表明:滑坡运动过程中,滑体对阶地易侵蚀基层的冲击刮铲作用显著,宏观上表现为滑坡前缘地层隆起与逆冲剪断。滑坡滑动产生的振动作用使阶地粉土发生液化,液化后的粉土在超孔隙水压力作用下沿上覆土体导水通道涌出,形成显著的"涌砂"现象。滑坡运动全过程历时84 s,滑体颗粒最大运动速度36.2 m/s,最大运动距离253.2 m,具有典型的"高速"、"远程"特征。分析得到2点结论:①泾阳南塬典型高速远程黄土滑坡运动过程可分为3个阶段,即,冲击置换的加速阶段(0～2.9 s)、滑覆铲刮的减速阶段(2.9～5.7s)与堆积推覆的慢速波动阶段(5.7～84 s);②滑体速度场变化特征明显,也可划分为3个阶段,即,加速阶段(0～2.9 s)、减速阶段(2.9～5.7 s)以及慢速波动阶段(5.7～84 s)。     

山区河道型水库滑坡涌浪对岸坡冲刷深度的研究

三峡库区滑坡频发,滑坡产生的涌浪经常对库区岸坡造成破坏。通过山区河道型水库滑坡物理模型试验,研究不同产状滑坡产生的涌浪对三种不同组成粒径岸坡的最大冲刷深度。通过分析首浪高度与滑坡体宽度、厚度以及滑面倾角的关系;涌浪沿程衰减规律;岸坡最大冲刷深度和岸坡前涌浪高度的关系;运用回归分析得到首浪高度经验计算公式、沿程涌浪衰减公式、岸坡最大冲刷深度的经验计算公式。最终得到受滑坡体产状以及滑坡入水点到岸坡距离影响的岸坡最大冲刷深度经验计算公式。研究成果可为三峡库区岸坡的维护提供相应参考。     

枯季梧州流量对龙滩水库泄流量的响应关系

枯季利用西江上游龙滩水库调节控制梧州流量以满足珠江河口压咸补淡的要求,是近年来保障河口地区供水安全的重要工程措施.文中将龙滩水库泄流过程与区间流域的自然径流过程作为整体统一考虑,利用数字流域模型建立龙滩-梧州区间无控开放性流域的降雨径流模拟分析系统;通过数值试验,分析了区间流域径流过程影响下梧州流量对龙滩泄流的响应关系.结果表明,龙滩泄流量是枯季梧州流量的主要组成部分,梧州流量与龙滩泄流量具有很好的线性关系,在枯水年和偏枯水年,龙滩最小压咸泄流量分别需要600m3/s和800m3/s;梧州流量对龙滩泄流的响应过程与龙滩泄流量及其变化有关,泄流量越大,变化越迅速,梧州流量的响应时间越短.     

金沙江白格滑坡运动过程分析及潜在不稳定岩体预测

2018年10月11日和11月3日于西藏江达县波罗乡白格村与四川省白玉县绒盖乡则巴村交界处,金沙江右岸先后发生两次滑坡,堵塞金沙江形成堰塞湖,经人工干预险情解除未造成严重损失。采用Voellmy流变模型,基于PCRaster环境使用MassMov2D模拟了两次滑坡的运动和堆积过程,并使用第二次滑坡的反演结果对白格滑坡滑源区的三处潜在不稳定岩体做了预测分析。模拟结果表明:MassMov2D可以用于金沙江白格滑坡这种滑坡-碎屑流的模拟,两次滑坡的主要堆积区域和堆积厚度均于实际情况接近;利用第二次滑坡模拟反演参数预测三处潜在不稳定岩体,假设三处不稳定岩土体同时失稳滑动,会形成64 m高的堰塞坝,可能再次堵塞金沙江形成堰塞湖。     

泄流坡滑坡稳定性模糊评价

以舟曲县泄流坡滑坡为例,将滑坡的稳定性分为五个等级,选用出了影响边坡稳定的19个因子及其分级标准,据各影响因子在引发滑坡滑动中的重要程度,给出了各因子的二级权重。建立了计算各影响因素隶属度的隶属函数和专家评定结果。利用建立的模糊综合评价模型对泄流坡滑坡稳定性进行评价,评价结果与实际情况相吻合。     

基于物质点法的远程滑坡碎屑流运动过程模拟及特征分析

目的 研究远程滑坡碎屑流运动过程以及运动过程中速度、滑动距离、动能变化,为滑坡碎屑流灾害的预防和治理提供参考。方法 基于物质点法,以塔合曼和乱石包两个远程滑坡碎屑流工程实例为背景,对两个滑坡碎屑流的运动过程进行数值模拟;并对塔合曼滑坡碎屑流运动过程中水平、垂直方向运动速度分布,内摩擦角对运动过程的影响,以及乱石包滑坡碎屑流铲刮效应对堆积形态、动能变化的影响进行分析。结果 两个滑坡碎屑流最终堆积形态模拟结果与实测结果吻合良好,验证了数值模拟结果的有效性;塔合曼滑坡碎屑流随着内摩擦角从18°增加到33°,动能峰值降低71.4%,最终势能增加54.4%,滑坡碎屑流的能量耗散减小47.8%;在乱石包滑坡碎屑流实例的模拟中,速度云图呈现了滑体速度场的层状分布特征。结论 内摩擦角对滑坡碎屑流的动力过程影响十分显著;乱石包滑坡碎屑流的滑体在高速滑移阶段存在强烈的内部剪切作用,并且铲刮效应对滑坡碎屑流的运动起到了一定的阻碍作用。     

金泉寺滑坡破坏机理及冲击强度定量分析

为了对滑坡冲击强度进行定量预测,以勉县金泉寺滑坡为研究对象,基于颗粒流离散元方法,结合对滑坡岩土体细观参数的双轴试验标定,构建了滑坡数值模型,对滑坡的变形破坏机理及其动力学过程进行了分析,选用冲击距离、冲击速度、冲击力3个指标对滑坡的冲击强度大小进行了定量预测。研究结果表明:金泉寺滑坡坡脚和滑坡后缘首先发生变形,然后滑坡坡体中部的锁固段发生贯通,并最终表现为前拉后推的复合式破坏特征;滑坡最大冲击距离为23. 52 m,最大冲击速度为4. 10 m/s,单位宽度最大冲击力为205 kN。相关结论与利用已有研究方法分析所得结论较为一致,认为滑坡运动过程中滑体内部颗粒碰撞及摩擦耗能对滑坡冲击强度的影响不可忽略。研究方法及成果对堆积层滑坡动力学过程分析及其风险定量评估研究具有重要的参考意义。     

粗粒土堆积体塌滑特性试验与数值研究

基于室内物理模型试验,研究粗颗粒土沿斜面塌滑、蔓延和堆积的整个运动过程;分析粗粒土堆积体初始状态、颗粒粒径、斜面倾角等因素对塌滑体的最终堆积状态参数(主要包括冲程,最大堆积厚度及其位置)的影响.基于离散单元数值分析方法,采用颗粒流程序软件,编写粗粒土堆积体塌滑运动的模拟程序,开展粗粒土堆积体塌滑过程的研究,数值模拟与室内试验结果基本一致.研究结果表明:堆积体最终状态几乎不受初始状态的影响;斜槽倾角对堆积体滑落稳定后最大堆积厚度所在水平位置影响较大,根据数值计算结果,拟合出斜槽倾角与最大堆积厚度所在水平位置的关系式;斜槽倾角对最终堆积形态有着较大的影响;随着斜槽倾角和粒径的增大,堆积体的冲程、最大堆积厚度的位置与坡角的距离增大,最大堆积厚度减小.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with