一种旋转塑性势面模型及非关联塑性流动法则     

徐日庆  蒋佳琪  冯苏阳  鞠露莹 《岩土力学》2020,41(5):1474-1482

为了较好地描述软土塑性应变发展规律，提出了一种改进的塑性流动模型。该模型采用了与屈服函数形式相同，但具有一定倾角 的塑性势函数。土体在变形过程中，塑性流动方向会依赖于塑性势面的旋转而变化，直至达到破坏状态。通过对常规三轴试验结果的分析可以发现：在剪切过程中，塑性势面旋转角的初值 与终值 较为稳定，不受围压变化影响。在此试验观察基础上，引入了归一化的旋转角参数 以及描述土体应力状态的参数 ，在采用蛋形势函数的情况下二者具有良好的分段线性关系。利用该关系，建立了改进的塑性流动法则，只需要2个额外的模型参数。对所提出的塑性流动模型进行了验证，计算结果表明该模型能较好地反映塑性应变的变化趋势。  相似文献   

构造-岩浆作用对热液活动的控制机理: 马努斯海盆为例   总被引：2，自引：2，他引：0  

马瑶  殷学博  王晓媛  陈帅  曾志刚 《海洋科学》2018,42(5):163-171

综述了马努斯海盆热液区构造特征、基底差异, 结合马努斯海盆热液区热液活动与构造-岩浆特征, 探讨了二者的耦合关系, 以及构造-岩浆作用对热液活动的影响和控制。马努斯海盆位于西南太平洋俾斯麦海的东北部, 是世界上扩张速度最快的海盆之一。马努斯海盆西部(马努斯扩张中心, Manus Spreading Center, MSC)主要由海盆扩张成熟期产生的大洋中脊玄武岩组成, 属于成熟弧后扩张中心,发育Vienna Woods热液区; 海盆东部(东南裂谷, Southeast Rift, SER)则是一个拉张裂谷, 处于扩张的早期阶段, 属于不成熟弧后扩张中心, 发育PACMANUS、DESMOS、SuSu Knolls三大热液区。MSC与大洋中脊的热液活动相似, 而SER因受到火山、俯冲作用影响更为显著, 其热液流体具有岩浆流体和俯冲流体的特征。与Vienna Woods热液压相比, PACMANUS、DESMOS以及SuSu Knolls三个热液区的水深相对较浅(1 150～1 740 m), 是地球内部热物质由内向外迁移的结果, 其下部岩浆作用强烈。此外,岩浆脱气作用和数值模拟结果表明, PACMANUS热液系统中具有岩浆流体的输入。与Vienna Woods热液区相比, PACMANUS、DESMOS、SuSu Knolls热液区的热液活动强度及流体组成主要受控于岩浆作用。  相似文献   

大别山及其周边现今垂直形变研究     

宋尚武  王庆良  郝明  周琳  刘立炜  胡亚轩 《大地测量与地球动力学》2018,38(1):32-35

基于1980年、2005年和2015年3期区域精密水准网观测资料，利用线性动态平差模型计算获取大别山地区水准网长期垂直运动速度场图像。研究发现，淮河平原地表下沉较为严重，大别山呈现弱隆升趋势运动，长江谷地边缘地区较大别山区呈现明显的隆升运动。跨郯庐断裂带水准剖面结果显示，垂直运动与地形呈负相关和弱相关。  相似文献   

Metal flux as an alternative parameter in evaluating the resource potential for co-rich ferromanganese crusts     

Hisaaki Sato 《Marine Georesources & Geotechnology》2018,36(7):768-780

We propose a geochemical parameter, “metal flux” in evaluating hydrogenetic Co-rich ferromanganese crust deposits in the Pacific seamount area, that is based on physical, chemical, and geological characterization of the integrated growth piles of crusts. We calculated the metal flux for fifteen sites from different depths ranging between 900-6000m from different seamounts. The secular and areal variations of metal flux indicate a strong geological controls, and also can be a reliable tool for estimating an economic potential of the crusts. The Co flux decreases with increasing water depth, followed by almost constant flux of Ni and Mn. The Al and Fe fluxes vary with regions, indicating higher values in the western regions near the island arc probably related to a supply from the Asian continents. The results imply that Co, a redox sensitive metal element, is controlled by redox conditions of seawater, while Fe and Al are by terrigenous input. The metal flux reflects global and regional conditions and controls the compositional diversity of metals, thus consequently, the parameter can be a reliable powerful tool to estimate or single out more potential areas.  相似文献   

辽东半岛五龙金矿床航空电磁场特征及找矿意义     

石连成  骆燕  江民忠  王志宏  朱琳  陈伟  韩鹏辉  陈志鹏 《地质学报》2020,94(10):3106-3119

五龙金矿床位于五龙矿集区中部，是矿集区内规模大的石英脉型金矿。为查明矿集区深部构造及指导深部找矿预测，需结合深部地球物理资料综合分析研究。本文基于五龙矿集区航空探测任务，并结合其成矿地质特征，研究了五龙金矿在平面、剖面、空间等维度的航磁、航空TEM、航空大地电磁特征及其找矿意义。研究表明：平面上矿体位于鸡心沟断裂东侧负磁背景场中NE与近SN、NW向弱磁异常带交汇处，中等 强剩余磁异常带的转折端、梯度带，视电阻率低阻区及中低阻梯度带，深部存在团块状视磁化率高值区；剖面上矿体位于“左低右高，上高下低”的视电阻率梯度带上，呈中低阻、低阻特征及强磁场区至弱磁场区的视磁化率梯度带上，呈浅部“上高下低”、深部“下高上低”的中等 弱磁特征；空间上矿体位于鸡心沟断裂东侧的断裂构造低阻带与岩体高阻异常带的梯度带。五龙金矿地质地球物理找矿标志的建立和深部高视磁化率异常区的存在，表明矿区深部1000~2000m空间与五龙金矿体视电阻率、视磁化率特征相似的地段，仍具有较好找矿潜力。  相似文献   

河北武城凸起地热田地热地质特征     

王迪  汪新伟  毛翔  武明辉  刘慧盈  张瑄  王婷灏 《地学前缘》2020,27(3):269-280

在“雄县模式”和环境压力的双重驱动下,河北地区已形成我国最大的地热供暖城市群。因此,研究武城凸起地热田地热地质特征,对河北省故城县地热开发具有重要的指导意义。本文通过测井、地震和区域地质资料,结合水化学特征、同位素测试结果的分析,系统分析了地热田的不同类型热储展布、储集层物性、地下热水补给来源和循环路径特征,并精细评价了地热资源量。结果表明武城凸起地热田热储类型主要为馆陶组砂岩热储和奥陶系岩溶热储。砂岩热储区域稳定分布,主要产水层为下馆陶组,底板埋深1 200~1 600 m,单井出水量79~123 m³/h, 井口水温52~54 ℃;岩溶热储有利区带主要分布在寒武—三叠系卷入的背斜核部,呈南北向带状展布,主要产水层为上马家沟组、下马家沟组和亮甲山组,顶板埋深2 100~2 900 m,单井出水量75~98 m³/h,井口水温82~85 ℃。地下热水来源为西部太行山脉和北部燕山山脉,热水沿着NE-SW向断裂破碎带和岩溶不整合面向上水平运移进入浅层热储,通过沧县隆起和邢衡隆起在武城凸起汇集,形成中低温地热田。地下热水质类型为Cl-Na型,最大循环深度为2 822.5~3 032.5 m,¹⁴C测年表明砂岩热储和岩溶热储年龄分别为21 ka和32 ka。明化镇组和石炭—二叠系分别为两套热储的直接盖层。武城凸起地热田地热资源量分层精细评价结果表明,热储地热资源量合计4.86×10¹⁰ GJ,折合标煤16.6×10⁸ t。年可开采地热资源量可满足供暖面积1.1×10⁸ m²,市场开发潜力巨大。  相似文献   

Gravity and magnetic field characteristics and regional ore prospecting of the Yili ancient continent,West Tianshan,Xinjiang Uygur Autonomous Region,China     

《China Geology》2020,3(1):104-112

Gold, iron, copper, lead-zinc and other mineral exploration in West Tianshan, Xinjiang Uygur Autonomous Region, has made remarkable progress in recent years. However, due to the dispute on the tectonic division of West Tianshan, the ore-controlling factors and the regional metallogenic laws are controversial. The authors analyze regional gravity data and notice that the high-value region corresponds to the Yili ancient continent, thus the southeastern boundary of the Yili ancient continent is delineated. Comparative analysis of gravity, aeromagnetic and geologic data reveals that the Tulasu basin, where some medium to large epithermal gold deposits locate, lies above the Yili ancient continent; the Yili Carboniferous-Permian rift extends in E-W direction, numbers of copper deposits have been found in the mid-west section of the rift which lies above the Yili ancient continent, whereas few copper deposits have been discovered in the east section which is outside the Yili ancient continent. Accordingly, the Yili ancient continent may he rich in gold, copper and other metal elements; the metal-bearing hydrothermal solution moves up with the activity of magmatism, and deposits in the favorable places (the Tulasu basin and the Yili Carboniferous-Permian rift), forming numerous small and medium gold, copper deposits, as well as some large and super-large gold deposits. Therefore, the tectonic-magmatic hydrothermal zone above the Yili ancient continent should be the prospective area for epithermal gold and copper polymetallic deposits.  相似文献   

页岩油的储层特征及其影响因素分析——以沾化凹陷罗家地区为例     

贾屾  姜在兴 《中国地质调查》2020,7(2):13-20

为查明沾化凹陷罗家地区古近系沙河街组三段下亚段页岩油的储层特征及其影响要素,通过岩心、薄片、扫描电镜等多种资料综合分析,开展页岩油储层岩性、储层空间类型、影响因素及页岩油储层评价参数的研究。结果表明: 综合矿物成分和沉积构造2个因素,可将研究区页岩油储层岩性划分为7种类型; 不同岩性储集空间发育有较大差异,纹层状泥质灰岩和纹层状灰岩储集空间最为发育,纹层状灰质泥岩储集空间较发育,块状泥岩储集空间发育一般,块状泥质灰岩、块状灰质泥岩及纹层状粉砂岩储集空间发育较差; 研究区页岩油储层储集空间的发育主要受矿物成分、沉积构造、有机质含量和赋存方式以及成岩作用的影响。以此为基础,选取方解石含量、纹层状构造、总有机碳(Total Organic Carbon,TOC)含量、镜质体反射率(R_o)及孔隙度作为页岩油储层评价参数,将沾化凹陷罗家地区页岩油储层分为优质储层、有利储层和不利储层3类。  相似文献   

Intercomparison of measurements of bulk snow density and water equivalent of snow cover with snow core samplers: Instrumental bias and variability induced by observers     

J. Ignacio López-Moreno  Leena Leppänen  Bartłomiej Luks  Ladislav Holko  Ghislain Picard  Alba Sanmiguel-Vallelado  Esteban Alonso-González  David C. Finger  Ali N. Arslan  Katalin Gillemot  Aynur Sensoy  Arda Sorman  M. Cansaran Ertaş  Steven R. Fassnacht  Charles Fierz  Christoph Marty 《水文研究》2020,34(14):3120-3133

Manually collected snow data are often considered as ground truth for many applications such as climatological or hydrological studies. However, there are many sources of uncertainty that are not quantified in detail. For the determination of water equivalent of snow cover (SWE), different snow core samplers and scales are used, but they are all based on the same measurement principle. We conducted two field campaigns with 9 samplers commonly used in observational measurements and research in Europe and northern America to better quantify uncertainties when measuring depth, density and SWE with core samplers. During the first campaign, as a first approach to distinguish snow variability measured at the plot and at the point scale, repeated measurements were taken along two 20 m long snow pits. The results revealed a much higher variability of SWE at the plot scale (resulting from both natural variability and instrumental bias) compared to repeated measurements at the same spot (resulting mostly from error induced by observers or very small scale variability of snow depth). The exceptionally homogeneous snowpack found in the second campaign permitted to almost neglect the natural variability of the snowpack properties and focus on the separation between instrumental bias and error induced by observers. Reported uncertainties refer to a shallow, homogeneous tundra-taiga snowpack less than 1 m deep (loose, mostly recrystallised snow and no wind impact). Under such measurement conditions, the uncertainty in bulk snow density estimation is about 5% for an individual instrument and is close to 10% among different instruments. Results confirmed that instrumental bias exceeded both the natural variability and the error induced by observers, even in the case when observers were not familiar with a given snow core sampler.  相似文献   

甘肃省地热资源赋存特征及潜力评价     

谢娜  喻生波  丁宏伟  张明泉 《中国地质》2020,47(6):1804-1812

甘肃省地热资源丰富，其地热资源的开发利用具有较大的潜力。本文介绍了甘肃省地热资源分布概况，结合地区构造、地热水化学特征、地热资源量及开发利用现状探讨了甘肃隆起山地对流型与沉积盆地传导型地热资源的赋存特征，并对两种类型地热资源潜力进行了分析评价。结果表明，沉积盆地地热资源分布于河西、陇西及陇东盆地等，热储类型为裂隙型和孔隙型，热储层自元古宙至新生代均有发育，岩性以砂岩为主；隆起山地型地热资源主要分布于祁连山和西秦岭造山带，热储类型为断裂破碎带，岩性以花岗岩为主；通过潜力计算得知，全省热量开采系数≥0.4的仅占29.17%，表明目前甘肃地热资源开采程度较低，开采潜力较大。  相似文献