扬中金源时代购物中心基坑降水数值模拟分析

基坑降水的成功与否,将对基坑开挖和周边环境产生重要影响,因此有必要对基坑降水方案进行评估。针对扬中金源时代购物中心基坑降水问题,采用MIDAS/GTS对基坑降水效果进行研究。首先,依据地勘报告中提供的土体渗透系数,结合单井、双井抽水试验结果,反演出MIDAS/GTS中需要的土层渗流系数和边界函数;然后利用反演得到的参数,建立了考虑回灌井补水效应的三维基坑降水效果分析模型,模拟基坑内水位降深与时间的变化关系,并对基坑降水效果进行分析和评估,以期指导土方开挖工程的施工。     

面板对加筋土挡墙影响的离心模型试验研究

加筋土挡墙因其特有的景观性能、协调变形性能而日益受到设计者青睐。面板作为加筋土挡墙的组成部分,对墙体的承载能力影响显著。针对现有设计规范无法考虑面板形式对结构自身力学变形特性的影响,设计并开展了整体式与分块式面板的离心模型试验。数据测试分析显示：整体式面板加载期的位移小于分块式面板位移;由于分块式面板位移较大,所以其水平土压力小于整体式面板土压力;加筋土挡墙面板底部存在应力集中现象;分块式面板筋-土界面的摩擦系数发挥值大于整体式面板数值,但两者均小于设计规范建议值;由于模型筋材长度较长并且连接件的存在,导致原型设计较为保守。     

Geological and Fluid Inclusion Constraints on Gold Deposition Processes of the Dayingezhuang Gold Deposit,Jiaodong Peninsula,China

The Dayingezhuang gold deposit, hosted mainly by Late Jurassic granitoids on Jiaodong Peninsula in eastern China, contains an estimated 170 t of gold and is one of the largest deposits within the Zhaoping fracture zone. The orebodies consist of auriferous altered pyrite–sericite–quartz granites that show Jiaojia-type (i.e., disseminated and veinlet) mineralization. Mineralization and alteration are structurally controlled by the NE- to NNE-striking Linglong detachment fault. The mineralization can be divided into four stages: (K-feldspar)–pyrite–sericite–quartz, quartz–gold–pyrite, quartz–gold–polymetallic sulfide, and quartz–carbonate, with the majority of the gold being produced in the second and third stages. Based on a combination of petrography, microthermometry, and laser Raman spectroscopy, three types of fluid inclusion were identified in the vein minerals: NaCl–H2O (A-type), CO2–H2O–NaCl (AC-type), and pure CO2 (PC-type). Quartz crystals in veinlets that formed during the first stage contain mainly AC-type fluid inclusions, with rare PC-type inclusions. These fluid inclusions homogenize at temperatures of 251°C–403°C and have low salinities of 2.2–9.4 wt% NaCl equivalent. Quartz crystals that formed in the second and third stages contain all three types of fluid inclusions, with total homogenization temperatures of 216°C–339°C and salinities of 1.8–13.8 wt% NaCl equivalent for the second stage and homogenization temperatures of 195°C–321°C and salinities of 1.4–13.3 wt% NaCl equivalent for the third stage. In contrast, quartz crystals that formed in the fourth stage contains mainly A-type fluid inclusions, with minor occurrences of AC-type inclusions; these inclusions have homogenization temperatures of 106°C–287°C and salinities of 0.5–7.7 wt% NaCl equivalent. Gold in the ore-forming fluids may have changed from Au(HS)0 as the dominant species under acidic conditions and at relatively high temperatures and fO2 in the early stages, to Au(HS)2– under neutral-pH conditions at lower temperatures and fO2 in the later stages. The precipitation of gold and other metals is inferred to be caused by a combination of fluid immiscibility and water–rock interaction.     

Analyses of the Compositional Characteristics and Sources of the Organochlorine Pesticides in the Surface Sediments of Guanghai Bay,Taishan City,Guangdong Province

Organochlorine pesticides (OCPs) are a class of toxic and harmful persistent organic pollutants widely found in environment. Hexachlorocyclohexane (HCHs) and DDTs are two of the most widely used OCPs (Qiu et al., 2004), so it is important to find out their compositional characteristics and sources in surface sediments. Guanghai Bay is located in the south of Guanghai Bay Industrial Park in Taishan City, Guangdong Province. It borders Huangmaohai to the east and Zhenhai Bay to the west, covering an area of about 236 square kilometers. In this study, surface sediments were collected at 16 sites in Guanghai Bay (Fig. 1). After the surface sediments were pretreated, GC‐MS was used to analyze OCPs. A total of 14 OCPs were detected and their content was shown in Table 1. The concentration of ΣOCPs ranged between 0.507～0.860ng·g‐1, with an average of 0.680 ng?g‐1. In general, the content of ΣOCPs was the highest at No. A12 site. The concentrations of these 14 detected OCPs ordered as dieldrin > epoxy heptachlor > P, P'‐DDD > γ‐HCH >endrin >aldrin > P, P'‐DDE >mirex >hexachlorobenzene >P, P'‐DDT > α‐HCH > δ‐HCH >β‐HCH > heptachlor.     

吉林省红旗岭矿区7号岩体群地质特征及对地质找矿的指导意义

红旗岭矿区的南东部存在7、32、33号三个岩体,一般统称为7号岩体群。7号岩体是矿区发现含铜、镍矿最大的岩体,32与33号岩体分布在7号岩体的北西部。通过对这三个岩体的地质特征进行分析,利用3Dmine软件建模技术,对三个岩体、岩相、矿体建立三维模型。对模型进行观察、分析,结合成岩成矿地质理论,发现三个岩体是由来自7号岩体的南东部深部岩浆源生成的,岩浆由7号岩体的南东部深部向北西方向侵入,地质历史上三个岩体是一个大岩体,只是经过长期的风化剥蚀和地质构造改造形成目前的3个岩体,显示7号岩体的南东部深部具有找矿潜力。     

吉林省柳河县半截沟铁矿床地质特征及找矿标志

吉林省柳河县半截沟铁矿床赋存于中太古界斜长角闪片麻岩、黑云斜长片麻岩中。矿体形态简单,呈似层状、扁豆状分布。该文总结了矿床地质特征,确定了该区铁矿床的找矿标志。     

滇黔北威信凹陷晚二叠世沉积环境与层序地层格架下的聚煤规律浅析

针对滇黔北威信凹陷晚二叠世含煤岩系的“海相-海陆过渡相-陆相”三相变化地带,利用地层剖面上的沉积构造、岩石组合、古生物特征等沉积相判别标志分析研究区的沉积环境及其空间演化,并总结煤质变化规律。在此基础上,通过识别层序与体系域关键界面,建立研究区晚二叠世含煤岩系的层序地层格架,充分讨论研究区厚煤层在层序地层格架下的聚煤规律。研究区自西向东依次为河流冲积平原体系、三角洲-潮坪体系及碳酸盐岩台地体系,成煤环境主要为河流冲积平原中的泛滥盆地河漫沼泽和三角洲-潮坪沉积体系中的上三角洲平原;厚煤层在层序地层中的位置与古地理背景有关,研究区C15,C19煤层形成于最大海泛面附近,C25煤层形成于初始海泛面附近;根据煤质变化规律和煤厚变化特征,在研究区西部的彝良-盐津一带有寻找优质煤炭资源的潜力。     

过去千年中国东部持续性严重干旱事件的模拟研究

文章利用CESM1.1(公共地球系统模式)模式过去千年集合试验结果,对模拟的过去千年中国东部持续性严重干旱事件的时空特征及发生机制进行了初步分析。模式模拟出过去千年中国东部发生了7次持续性严重干旱事件,分别为883~910年、951~977年、1253~1305年、1327~1346年、1471~1488年、1587~1610年和1688~1699年干旱事件,其中仅1471~1488年干旱事件与中国东部旱涝指数对应较好,表明模式对中国东部干旱事件的模拟能力较低。这7次干旱事件均与模拟的ENSO(厄尔尼诺-南方涛动)负位相状态相对应,揭示ENSO可能对中国东部干旱事件的发生起了非常重要的作用。模拟分析结果显示,1253~1305年干旱事件前期可能主要受火山活动驱动,后期则可能受到太阳活动和自然内部变率的影响。另外,1587~1610年干旱事件后期可能也受到火山活动的影响;883~910年和951~977年干旱事件则完全受自然内部变率的影响。对1327~1346年、1471~1488年和1688~1699年这3次干旱事件,无法分辨外强迫和内部变率ENSO的各自贡献。