教学课程资源库 更多>>

关键词： Elastic deformation  

摘要： The study on the evolution characteristics of coal permeability is of great significance for rationally determining gas extraction parameters and increasing gas extraction efficiency. In order to study the effects of different coal stresses and gas pressures on coal permeability, the experiment on the deformation of stress-loaded coal and gas adsorption-diffusion was conducted, the segmented dynamic model of coal permeability was established, and the rationality of the established model was verified by the experimental results. The results shown that the gas adsorption amount and coal deformation both shown a Langmuir-type with the increasing gas pressure, and the dynamic diffusion coefficient of gas decreased exponentially with time. As the gas pressure decreased, the expansion deformation of the stress-loaded coal decreased, and the permeability increased gradually. The permeability and expansion deformation of stress-loaded coal gradually decreased with the increasing stress. The coal permeability shown a "V" shape with continuous stress loading, and it reached the smallest at the stress peak. The coupling between matrix and fracture deformation caused by gas adsorption, the dynamic diffusion of gas in matrix, and the mass exchange between matrix and fracture were all considered in the established permeability model of coal. The rationality of established segmented model of coal permeability was verified by the experimental results. The permeability model of coal based on elastic deformation can reflect the permeability evolution at the stage of elastic deformation. Within the experimental range, the absolute error between the experimental test and numerical simulation results of coal permeability was −0.135×10−15~0.296×10−15 m2, and the absolute error of volumetric strain of the coal due to gas seepage was −0.327×10−5~2.026×10−5. The permeability model considering plastic deformation can also reflect the permeability after stress peak. The error between experime

关键词： Flooding   Flood water storage   Carbonate rocks   Karst   Mediterranean region  

摘要： Flooding is a recurring natural phenomenon that can have both life-giving and destructive aspects. In natural environments, floods are often an important element of the seasonal hydrologic cycle that provides water and nutrients to soil, supporting unique, rich and diverse ecosystems. However, flood events can also represent a destructive force that can endanger lives and cause significant damage in urban areas. Karst areas, in particular, are unique because of their special hydraulic characteristics in terms of flood occurrence, the dependence of ecosystems on such events, and attempts to actively store and manage floods. In this article, the hydraulic response of karst aquifers to heavy precipitation events, flood generation, and engineering interventions for flood control are discussed using several examples from karst areas in the Mediterranean region. Flooding mechanisms and regulatory structures in karst poljes are considered using several typical examples from the Dinaric mountain range. In addition, different variants of groundwater abstraction for increasing storage capacity and flood control are presented using examples from France and Montenegro. Managed aquifer recharge in karst areas and adjacent aquifers is demonstrated with examples from Jordan and Algeria. Finally, failed attempts at flood storage in karst reservoirs are presented with examples from Spain and Montenegro. These examples of flood retention in karst areas show the wide range of planning and technical measures and remind us of possible risks and failures in implementation as well as some positive and negative impacts on the environment and especially on ecosystems.

关键词： 地下结构抗震   大直径竖井   土-结动力相互作用   地震响应解析解  

摘要： 已有震害经验表明，地下竖井结构遭受地震威胁且出现了严重的震害实例，为了得到竖井结构地震响应，基于P asternak地基和T imoshenko梁理论，在已有考虑场地土层与竖井结构法向土压力作用的基础上，进一步考虑了场地土层与竖井结构的切向剪力作用，采用“梁-弹簧”模型建立了大直径竖井-场地土层动力相互作用系统分析模型，研究水平向地震作用下大直径竖井地震响应解析解。分别从竖井长径比、内外径比、竖井与场地弹性模量比值和竖井底部边界条件的角度出发，对竖井沿深度方向的峰值地震响应进行分析，结果发现竖井长径比减小会导致竖井沿深度方向内力峰值响应增大；竖井内外径比的增大会使竖井沿深度方向峰值内力响应减小；随着竖井与场地弹性模量比值的增大，竖井沿深度方向内力峰值响应会逐渐增大；弹性土层地基下的竖井位移响应比嵌岩型地基大，沿竖井深度方向嵌岩型地基下的剪力响应显著大于弹性土层地基，在底部位置处嵌岩型竖井的弯矩峰值响应较大。

关键词： 坡地型弃渣场   振动台   数值模拟   动力响应敏感性分析   失稳模式  

摘要： 为研究坡地型弃渣场地震动响应敏感性及失稳模式，本文以坡地型弃渣场为研究对象，通过振动台模型试验对数值模拟进行校正，以证明利用数值模拟研究坡地型弃渣场的地震动响应的可行性。数值模拟考虑原始斜坡第四系覆盖层、渣体层和地震动3大类因素，研究弃渣场地震动响应规律和失稳模式，探讨失稳机制。研究结果表明：（1）弃渣场地震动响应随堆渣高度、坡度、第四系层倾角、地震动幅值、频率的增加而增大，随第四系层厚度增加而减小；（2）初步获得了坡地型弃渣场地震动响应影响因素敏感性大小：第四系层倾角>第四系层厚度>堆渣坡度>堆渣高度（弃渣场几何参数）、地震动幅值>地震动频率>地震动持时（地震参数）；（3）结合试验结果，修正了地震作用下坡地型弃渣场3类失稳模式：①“渣-覆界面滑移”模式，②“渣体振动溃散”模式，③“第四系层蠕变滑移”模式。综合上述分析结果，地震作用下弃渣场主要受堆渣高度、坡度、第四系倾角等影响，为弃渣场选址与堆置方案设计具有重要参考意义。本文提出的坡地型弃渣场失稳模式可为弃渣场防治措施提供依据。

关键词： 石棉县   滑坡易发性评价   时序InSAR   动态评价因子   最大熵模型  

摘要： 滑坡作为一种对自然和社会环境造成极大破坏的地质灾害，其易发性评价对防灾减灾至关重要。现有的滑坡数据库常作为滑坡易发性评价的数据基础，由于更新不及时，存在时效性差和不全面等问题。此外，传统的滑坡易发性评价方法主要依赖于静态数据(如地形，地质，水文)，缺乏动态数据(如地表形变)，难以全面捕捉正在变形的滑坡特征，导致评价的可靠性较差。本文结合光学遥感技术和合成孔径雷达干涉测量技术（Interferometric Synthetic Aperture Radar，InSAR）识别研究区滑坡并获取地表形变作为动态评价因子，结合静态评价因子，采用联合训练和加权叠加两种方法，耦合最大熵模型（Maximum Entropy，MaxEnt），并使用迭代自组织（Iterative Self-Organizing，ISO）聚类算法对石棉县进行滑坡易发性评价及分区。结果表明：（1）综合光学遥感技术和InSAR技术两种方法，共识别出研究区139处滑坡，石棉县滑坡灾害高易发区主要分布于河流和道路两侧，滑坡灾害点的分布与所划分区有很好的吻合性。（2）补充InSAR形变因子在一定程度上提高了6.1%的易发性精度（AUC=0.921），同时显著的降低了评估结果中出现假阳性和假阴性的情况，提高了模型的精确性。该研究突出了将InSAR形变信息融入滑坡易发性模型中的优势，可为石棉县滑坡灾害预防提供重要支撑。

关键词： 工业建筑基础设计   桩基础   岩溶  

摘要： 根据结构柱底轴力及项目造价,对位于广州岩溶地区的某工业建筑基础进行三种设计方案对比分析.方案一采用灌注桩单柱单桩,方案二采用预应力管桩,方案三采用灌注桩多桩基础.经过专家对三种方案评审后,选定本项目的最终方案,找出结构安全状态下的最优基础形式,可供类似项目参考.

关键词： 多点反应谱   人工边界   土-结构动力相互作用   等效地震荷载  

摘要： 本文提出并建立了黏弹性人工边界-土-结构相互作用（VSAB-SSI）体系可规范化的高精高效简洁多点地震反应谱。提出人工边界与土共同节点自由场与散射场相分离的思想，建立该体系在绝对坐标系下的运动方程，直接抵消了等效地震荷载中的黏滞力和弹性力。提出并论证边界非经典阻尼完全经典化的途径，由此将V SAB-SSI体系转换为经典比例阻尼模型，实现了实模态法解耦动力方程，摆脱了复模态法才能确保其准确性的固有认识推导得到了V SAB-SSI体系实模态分解下的高精、高效、简洁多点反应谱表达式，验证其计算结果的精确性和计算效率的优越性。结果表明：本文方法使得多点反应谱的相关系数由以往表达式中的1 8项减少至3项，解决了传统方法过计算程烦冗和计算参数多的弊端。

关键词： 红寨滑坡   古滑坡   变形分区   破坏特征   成因分析  

摘要： 2020年9月17日,贵州省晴隆县鸡场镇红寨村发生滑坡灾害,导致134栋房屋严重损毁,127户569人紧急避险.通过调查发现,红寨滑坡是一处规模达6.25×106m3的深层大型滑坡,地表房屋及基础设施破坏严重,但整个滑坡运动距离极短.通过对地形地貌和岩土体结构及物质成分组成的分析、水系变动判断及钻孔揭露的多层滑面等综合分析认为,红寨滑坡是一处顺层的复活古滑坡.为分析研究该滑坡的变形特征和复活成因,采用无人机航测、工程地质调查、岩土体勘查、地球物理勘探等手段,获取了详细的灾害发育特征、影响因素及古滑坡的辨识特征等数据.分析结果表明:红寨滑坡可根据变形破坏特征及应力传递方向分为A、B、C、D4个分区,其中B区又根据相对滑移量分为B1、B2亚区;滑坡的变形复活是在高陡的地形地貌、复杂的岩体结构、软弱的工程岩组和持续地表水入渗等共同作用下发生的;滑坡后缘圈椅状地形、滑体与周围岩土体的物质差异、断层切割前缘及水系堆积物的变迁等多方面特征验证了古滑坡的事实.