循环抽注水作用下承压含水层砂土的变形特性

为探讨人工回灌和地下水位季节性变化等因素对承压含水层砂土变形特性的影响,利用FlowTracⅡ增量固结试验系统,设计了符合承压含水层砂土应力状态、符合抽注水应力路径的单向压缩试验,研究了循环抽注水作用对砂土变形特性的影响规律及抽注水作用下砂土变形特性的影响因素。试验结果表明:抽水作用(加载)下砂土产生压缩变形,注水作用(卸载)下,砂土变形呈现压缩和回弹两种现象,且砂土孔隙比大(密度小)时易发生注水压缩现象;循环抽注水作用下砂土总体呈现压缩变形特性,随抽注水循环次数的增加和前期固结压力增大,注水作用下砂土变形逐渐由压缩向回弹转化。基于砂土结构演变,构建了以弹性理论和最小势能原理为基础的抽注水作用下砂土变形机理,解释了注水作用过程中砂土变形呈现的回弹与压缩交替波动的试验现象,用试验结果总结了注水强度、前期固结压力、注水速率等因素对砂土变形特性的影响规律,验证了抽注水作用下砂土变形机理的合理性。     

舱室密闭空间中爆炸载荷后燃烧效应数值计算研究

为准确分析梯恩梯炸药在密闭空间中的爆炸载荷,在统一设施标准模型和基于能量守恒的简化计算公式基础上,提出了一种计算爆炸产物后燃烧能量的方法。该方法应用到基于有限元分析软件ANSYS/AUTODYN平台的数值模拟中,实现负氧平衡炸药在密闭空间中爆炸过程的数值仿真计算。计算结果与试验测试结果表明：梯恩梯炸药在密闭空间中发生爆炸时,其爆轰产物的后燃烧效应不可忽视;不考虑爆炸产物的后燃烧效应,数值计算得到的准静态压力较试验值低55%以上,50 ms内冲量较试验值低49%以上;将爆轰产物的后燃烧能量计入后,爆炸压力及冲量时程的计算值与试验值吻合较好,为结构受爆炸载荷响应分析提供了准确的输入载荷。     

湛江冯村垃圾场对中深层承压水污染的可能性及其防治

根据湛江冯村垃圾场所处的原生及次生地质环境条件,采用水文地质学及地下水动力学的理论与方法,对冯村垃圾场潜在污染中深层承压水的可能性、危害性及防治对策进行初步探讨。结果表明:冯村垃圾场建于地下水循环系统的补给区,地形切割强烈,包气带自净能力差,浅层潜水与中深层承压水之间的水头差较大,存在污染中深层承压水的可能性。建议贯彻以防为主、防治结合的原则,禁止在冯村一带再建垃圾填埋场,并设立防治分区,建立动态监测网络系统及地下水管理模型。     

浅谈煤矿井下承压含水层钻进勘探的实践——以峰峰矿区为例

该文通过大量井下承压含水层钻进实践 ,总结出高承压水头时孔口管的固定方法、防止井喷设施的制备、减压装置的安装及钻孔内含水段的隔离等关键技术。     

方钢约束混凝土拱架补强机制研究及应用

方钢约束混凝土(SQCC)拱架作为复杂条件地下工程中的一种新型支护方式,具备很高的支护强度和后期承载能力,而拱架留设的灌浆孔因局部削弱和应力集中效应而成为拱架的关键破坏部位,对拱架整体承载能力具有很大的影响,需对灌浆孔进行补强处理以提高拱架开孔后的整体强度.针对SQCC开孔短柱进行室内试验及数值试验,对比分析短柱变形破坏形态、荷载位移曲线及极限承载力等力学性能,研究方钢约束混凝土拱架补强机制;建立约束混凝土强度及经济指标,综合对比短柱补强效果.以SQCC150×8短柱为例,留设灌浆孔后短柱极限承载力相比SQCC短柱降低29.9%;侧弯钢板补强(ASS)后短柱的强度指标达148.7%,经济指标为90.8%,补强效果最好,且补强钢板长度在180~240 mm范围内,厚度为8 mm时,侧弯钢板对灌浆孔补强效果最明显,经济指标增长率最大.侧弯钢板补强试验结果在全比尺拱架室内试验中得到充分验证,在现场巷道支护应用中效果良好,研究成果为约束混凝土支护设计提供了依据.     

Transformation of Organonitrogen-Encapsulated MOFs into N-Doped Fe3O4@C Nanopolyhedron via CVD Super-Assembly for Photochemical Oxidation

Development of nano-structured metal oxides/heteroatom composites with controlled components and structure for photochemical oxidation still remains a great challenge. Here, a new and versatile strategy is reported for transformation of organonitrogen-encapsulated metal-organic frameworks (MOFs) into N-doped Fe₃O₄@C nanopolyhedron by chemical vapor deposition-induced super-assembly method. Strong confined interaction between organonitrogen guests (urea, thiourea, melamine, and dimethylimidazole) and Fe nodes of MOFs realizes reconstruction of crystal structure and introduction of N species. With the novel approach, the uniform dispersion of guests and perfect metallic/heteroatom interfacial is obtained. Compared with MOFs-derived Fe₂O₃/C, the heteroatom/defect-to-metal cluster charge transfer excitations lead N-doped Fe₃O₄@C to exhibit more superior activity for photocatalytic oxidation (turn-over frequencies as high as 3.72 h⁻¹). It demonstrates that the introduction of abundant pyrrole-N and oxygen vacancies on carbon interface boosts the advance of photo-generated carrier transfer. The study offers a simple and promising strategy for the design of novel metal oxides/heteroatom composite with adjustable structure and functions.     

Cavitation-driven Deformable Microchambers Inspired by Fast Microscale Movements of Ferns

Annulus cells of fern sporangia spontaneously deform driven by water transpiration and cavitation, resulting in the peculiar macroscale catapult-like movement of the sporangium. Annulus cells' behavior, if artificially replicated, can inspire a novel class of fast actuators composed of annulus-mimicking units. However, the transpiration and cavitation-driven dynamics observed in annulus cells is never reproduced. Here, prismatic microcavities are assembled with a polydimethylsiloxane (PDMS) microfilm to realize artificial microchambers that mimic the annulus cells, replicating for the first time their evaporation-driven collapse and their fast return triggered by the nucleation of bubbles. The microchambers, in turn, can be fabricated in adjacency, resulting in bending arrays driven by transpiration. Working with an artificial system allows this study to investigate the fluidic phenomena arising from the interplay of a soft, semi-permeable membrane with a micro-confined liquid bounded by rigid walls. First, the microchambers aspect ratio influences the membrane dynamics and the bubble shape (either spherical or non-spherical). Second, the growth rate of the bubble interplay with the membrane in the expansion dynamics. This study's results demonstrate the artificial replication of annulus cells' behavior, offering a plant-like solution to realize fast, microscale movements, and a novel tool to investigate complex fluidic mechanisms involving micro-confined cavitation.     

高喷技术在永乐水电站工程中的应用

介绍了利用高喷技术处理含承压水的永久性建筑物基础的工程实例。高喷技术对恶劣地质情况的适应性有所提高。     

MOF‐Confined Sub‐2 nm Atomically Ordered Intermetallic PdZn Nanoparticles as High‐Performance Catalysts for Selective Hydrogenation of Acetylene

Controllable synthesis of ultrasmall atomically ordered intermetallic nanoparticles is a challenging task, owing to the high temperature commonly required for the formation of intermetallic phases. Here, a metal–organic framework (MOF)‐confined co‐reduction strategy is developed for the preparation of sub‐2 nm intermetallic PdZn nanoparticles, by employing the well‐defined porous structures of calcinated ZIF‐8 (ZIF‐8C) and an in situ co‐reduction therein. HAADF‐STEM, HRTEM, and EDS characterizations reveal the homogeneous dispersion of these sub‐2 nm intermetallic PdZn nanoparticles within the ZIF‐8C frameworks. XRD, XPS, and EXAFS measurements further confirm the atomically ordered intermetallic phase nature of these sub‐2 nm PdZn nanoparticles. Selective hydrogenation of acetylene evaluation results show the excellent catalytic properties of the sub‐2 nm intermetallic PdZn, which result from the energetically more favorable path for acetylene hydrogenation and ethylene desorption over the ultrasmall particles than over larger‐sized intermetallic PdZn as revealed by density functional theory (DFT) calculations. Moreover, this protocol is also extendable for the preparation of sub‐2 nm intermetallic PtZn nanoparticles and is expected to provide a novel methodology in synthesizing ultrasmall atomically ordered intermetallic nanomaterials by rationally functionalizing MOFs.