砂泥岩间互地层裂缝延伸规律探讨

目前裂缝预测主要集中在对开度、密度和发育强度等参数的半定量或定量化预测方面,对裂缝的延伸规律和穿透性研究缺少深入研究。针对这种情况,文中以天山山前某油田沙泥岩间互地层为例,采用应力场数值模拟法建立应力场与裂缝参数之间的定量关系,从而实现裂缝在沙泥岩间互地层中的的延伸规律与穿透性研究。模拟结果显示,越薄的砂岩层越容易产生构造裂缝,而砂岩厚度对砂岩中产生的裂缝在泥岩中的延伸长度影响很小,几乎可以忽略,且对延伸到泥岩中裂缝的孔隙度影响也不大,即不管泥岩上下砂岩层的厚度如何,延伸到泥岩中的裂缝孔隙度变化不大,均在038％左右;砂泥岩互层处裂缝在泥岩中延伸长度一般为15~2 m,当泥岩厚度为4 m左右时,砂岩裂缝恰好无法穿透泥岩,泥岩可作为有效的封盖层。     

Characteristic Test Study on Bearing Capacity of Suction Caisson Foundation Under Vertical Load

Suction caisson foundations are often subjected to vertical uplift loads, but there are still no wide and spread engineering specifications on design and calculation method for uplift bearing capacity of suction caisson foundation.So it is important to establish an uplift failure criterion. In order to study the uplift bearing mechanism and failure mode of suction caisson foundation, a series of model tests were carried out considering the effects of aspect ratio,soil permeability and loading mode. Test results indicate that the residual negative pressure at the top of caisson is beneficial to enhance uplift bearing capacity. The smaller the permeability coefficient is, the higher the residual negative pressure will be. And the residual negative pressure is approximately equal to the water head that causes seepage in the caisson. When the load reaches the ultimate bearing capacity, both the top and bottom negative pressures are smaller than Su and both the top and bottom reverse bearing capacity factors are smaller than 1.0 in soft clay. Combined the uplift bearing characteristics of caisson in sandy soil and soft clay, the bearing capacity composition and the calculation method are proposed. It can provide a reference for the engineering design of suction caisson foundation under vertical load.     

金川含矿超镁铁岩侵入体侵位序列

金川铜镍硫化物矿床是世界第三大镍矿床,但其成岩成矿过程及侵位机制一直存在较大争论。根据金川含矿超镁铁岩岩石学特征、穿插关系、矿物成分及地球化学特征,提出了金川含矿岩体5阶段的成岩、成矿侵位序列,它们分别是:(1)超镁铁质岩浆侵位;(2)浸染状硫化物矿浆侵位;(3)网状硫化物矿浆侵位;(4)块状硫化物矿浆侵位;(5)铂钯富集体侵位。金川铜镍(铂)矿床中Ni,Cu,Pt,Pd,Rh,Ir,Ru,及Co与S呈正相关关系;当ω(S)=5%～15%时,铂族元素发生明显的分离作用,铂族金属主要富集在铂钯富集体中。铂钯富集体是硫化物矿浆经单硫化物固溶体结晶后的残余熔浆;块状矿石是单硫化物固溶体堆积而成的产物。金川铜镍硫化物矿床的侵位机制为岩墙型岩浆通道。     

川南煤田象顶井田瓦斯赋存特征及影响因素

根据象顶井田大量瓦斯实测资料分析,区内瓦斯含量高分带不明显,沼气带在埋深100m以下,瓦斯含量有随埋深增加而增大的趋势,但相关性不显著,地质构造及水文条件是影响区内瓦斯分布的主要因素。井田内先期发育的压性层间滑动断层(f701)及其派生断层纵贯全区,导致构造煤发育,瓦斯含量高;中部及西南部的F39、F418、F428、F405张性正断层切割了先期的压性断层,断层破碎带及裂隙为瓦斯逸散提供了通道,同时断层使上盘煤层与下盘岩溶发育的茅口灰岩直接接触,加速了瓦斯的逸散,致使该区域内煤层瓦斯含量降低,形成了井田北东部瓦斯含量高、中部及南西部含量相对较低的格局。根据煤体结构、构造分布、煤层特征,预测区内C19煤层易发生突出区域位于井田北东部。     

Seismic resilience assessment of corroded reinforced concrete structures designed to the Chinese codes

The natural landscape in China exposes many existing RC buildings to aggressive environments.Such exposure can lead to deterioration in structural performance with regard to resisting events such as earthquakes.Corrosion of embedded reinforcement is one of the most common mechanisms by which such structural degradation occurs.There has been increasing attention in recent years toward seismic resilience in communities and their constituent construction;however,to date,studies have neglected the effect of natural aging.This study aims to examine the effect of reinforcement corrosion on the seismic resilience of RC frames that are designed according to Chinese seismic design codes.A total of twenty RC frames are used to represent design and construction that is typical of coastal China,with consideration given to various seismic fortification levels and elevation arrangements.Seismic fragility relationships are developed for case frames under varying levels of reinforcement corrosion,i.e.,corrosion rates are increased from 5%to 15%.Subsequently,the seismic resilience levels of uncorroded and corroded RC frames are compared using a normalized loss factor.It was found that the loss of resilience of the corroded frames is greater than that of their uncorroded counterparts.At the Rare Earthquake hazard level,the corrosioninduced increase in loss of resilience can be more than 200%,showing the significant effect of reinforcement corrosion on structural resilience under the influence of earthquakes.     

造山带挤出构造与高压-超高压岩石剥露机制:以大别山为例

造山带挤出构造阐述了被边界断裂所围限的造山带深变质块体,在造山带内部垂向和(或)侧向应力的作用下折返变形的过程。研究主要集中在挤出块体的几何形态及其内部变形样式、边界断裂特征、挤出路径以及挤出动力来源等4个方面,其研究目的主要是为了解决造山带深变质岩石折返剥露的机制问题。依据挤出块体的挤出方向与造山带主体走向之间的关系,在三维球形坐标系Lx-Ly-Lz中,将造山带挤出构造大致分为7个端员类型(Ⅰ型～Ⅶ型)。其中Lx为造山带或俯冲带的主体走向;Ly呈水平方向并与Lx相垂直;Lz垂直于Lx和Ly所构成的平面。这些基本端员类型的组合及其之间的过渡类型可以详尽地诠释大别山印支期高压-超高压岩石的挤出过程。其中榴辉岩相挤出阶段介于Ⅳ型与Ⅶ型挤出构造之间,角闪岩相挤出阶段介于Ⅱ型与Ⅵ型挤出构造之间并可能具有渠道流挤出模式,而绿片岩相挤出阶段类似于Ⅴ型挤出构造。     

从地震信息看阿尔金断裂带构造和塔里木盆地花彩弧断裂体系

阿尔金断裂带由多条断裂组成,主要有阿尔金断裂、且末断裂、三危山断裂。其中阿尔金断裂为主断裂,它呈左旋走滑兼具逆冲性质,中生代—古近纪为左旋走滑,新近纪由东南向西北逆冲推覆。且末断裂和三危山断裂均具左旋走滑性质。且末断裂受统一的阿尔金断裂带左旋应力场控制,但又叠加了塔里木台盆区向南挤压的应力场,从而具有双重属性。塔里木盆地的断裂总体上组成古生界塔北花彩弧断裂束和塔南花彩弧断裂束,展布成全盆地的菱形断裂系统,且末断裂构成其东南边界。在该菱形断裂系统的北弧顶和菱形内的中央轴部为背冲式的构造断裂带,显示挤压特征;在花彩弧两翼转弯处展布正花状构造样式,显示走滑特征。阿尔金断裂带及其两侧,主要在柴达木、塔里木两大盆地发现了大油气田,两者都是由断层控制油气的垂向运移与分布。柴达木盆地具有双重断—坳的特点,但油气田只分布在中—新生界构造层内;塔里木盆地,南北翘板式的构造运动是其形成复式油气区的最重要的地质构造条件。     

海南岛屯昌地区泥盆纪片麻状花岗岩锆石SHRIMP U-Pb年龄报道

1 研究目的(Objective) 海南地块古生代岩浆作用与特提斯洋的演化息息相关,古特提斯洋及原特提斯洋从海南岛及周边何处而东延,洋壳俯冲过程中岩浆作用的时限及构造演化过程与特征,是海南岛前中生代地质演化长期未解决的重要地质问题.长期以来,海南地块与原特提斯洋俯冲相关的地质记录及精确年代学数据甚少,本次工作在海南岛中...     

澳大利亚北领地温盖特(Wingates)金矿床地质特征及找矿潜力

澳大利亚温盖特金矿位于北澳克拉通,是湖南省有色地质勘查局成功"走出去"的第一站。本文通过研究该矿床的大地构造背景、矿物学、岩石学、热液蚀变、地球化学等特征,发现温盖特金矿具有热泉型金矿的典型特征:矿床产于张性的大地构造背景下,成矿深度浅且与火山岩浆热液活动关系密切,赋矿围岩为火山岩,矿石为网脉-细脉状,地表有泉华和爆破角砾岩发育,青磐岩化带、绢云母化-泥化带、硅化带的热液蚀变分带明显,具有汞-锑-砷、铅-锌-铜的微量元素组合。目前已经揭露的金矿体和金矿点表明本区深部具有较好的找矿前景。通过与热泉型金矿成矿模式从平面和剖面上进行对比,指出了温盖特金矿的找矿靶区为8~23线之间的贫矿带深部区域。     

青藏高原东北部阶段性变形隆升：西宁、贵德盆地高精度磁性地层和盆地演化记录

青藏高原东北部的形成演化是检验高原隆升模型及其驱动季风-干旱环境形成假说的关键。青海贵德和西宁盆地新生代高精度磁性地层和盆地演化揭示出贵德和西宁盆地在早新生代两个盆地曾经为一个统一的、发育于东昆仑山前的弱挤压型陆内挠曲盆地或前陆盆地,可能包括兰州盆地、循化-化隆盆地和祁连山东部一些盆地在内的周边地区都向这个统一的盆地内注入水流和沉积物质,在西宁一带形成汇水中心,并在当时为行星风系的亚热带副高压带作用下形成巨厚的膏盐层。从约21Ma的中新世早期开始,前陆盆地挠曲下沉明显加剧,盆地早期地层被挤压变形,形成盆地中最显著的角度不整合,推测分隔贵德盆地东部的海宴—泽库右旋断裂强烈活动,分隔贵德和西宁盆地的拉脊山东部开始隆升,贵德盆地河流水系由北转向西流,至中中新世,隆升可能席卷整个拉脊山,贵德盆地水系明显南流,盆地挤压中心由早先的昆仑山前转移至拉脊山两侧。从约8Ma开始,拉脊山开始强烈阶段性幕式(3.6、2.6及1.8Ma)变形隆升,导致两侧断层以花状向盆地中心逐步扩展,断裂、掀斜和褶皱地层,盆地转变成山间盆地,并在约1.8Ma的强烈变形隆升后,黄河出现,紧接着形成上千米深切河谷和7级阶地,高原东北部现今构造地貌沉积格局最终形成。上述盆地形成演化过程总体揭示出印度板块碰撞早期最远端的高原东北部就已经开始变形隆升响应,这个过程阶段性由弱至强,至8Ma以来达到最大,反映了高原南北的同步变形隆升但幅度不同的动力学过程与形成模式,可能指示了脆性上地壳块体间柔性变形、块体内刚性挤压破裂变形和塑性下地壳连续变形增厚与流动的共同作用机制。