甘肃金川矿区构造应力场与构造演化研究          下载免费PDF全文

和秋姣  赖健清  毛先成  肖文舟  艾启兴  刘烨  杜日俊 《地质找矿论丛》2019,34(2):265-273

文章统计分析了金川矿区内地层和侵入体中的节理构造,对矿区内的共轭剪节理进行配套、分期,综合区域构造演化史后分析了矿区构造应力场。研究表明,金川矿区从新太古代到古生代至少受到4期古构造应力的作用。第一期构造应力场为NS向的挤压,由阴山陆块与鄂尔多斯陆块碰撞形成华北古陆西部陆块引起。第二期构造应力场为NE-SW向的挤压,与华北克拉通东、西陆块碰撞拼合并参与Columbia超大陆拼合事件有关;其后阿拉善陆块与华南陆块参与Rodinia超大陆拼合事件,应力场持续作用。第三期构造应力场为近NS向的挤压,由祁连洋不断向北俯冲引起。第四期构造应力场为NNE-SSW向的挤压,与祁连造山带发生的强烈造山运动有关。  相似文献   

胶莱盆地在南黄海的延伸:来自OBS深地震探测的新证据     

祁江豪  吴志强  张训华  侯方辉 《吉林大学学报(地球科学版)》2019,49(1):106-114

为了识别胶莱盆地海阳凹陷在南黄海地区的东部延伸边界,利用穿越南黄海的OBS2013-SYS深地震测线开展2D速度结构模拟,在测线NW方向位于千里岩隆起带的OBS（海底地震仪）站位均观察到了折合走时突然增加的现象。速度结构模型显示胶莱盆地东侧海阳凹陷附近海域存在明显的低速沉积层增厚现象,模型自OBS06站位向NW方向,沉积层厚度由小于1.0 km显著增厚至2.5 km左右,推测该处为胶莱盆地海阳凹陷的东部边界断裂。结合前人在海阳凹陷识别出的控盆断裂进行分析,厘定了海阳凹陷在海区大体的构造边界和沉积中心,认为胶莱盆地东部控盆断裂可能延伸至连云港-石岛断裂一线,与嘉山-响水-千里岩断裂构成千里岩隆起带南北边界断裂带的一部分。海阳凹陷沉降中心可能位于南黄海海区连云港-石岛断裂北侧海阳凹陷的NE方向,发育的厚层白垩系可能存在较好的油气前景。  相似文献   

拉林铁路板块缝合带隧道地应力分析     

欧小强  王奭  李永亮  刘志强  郑宗溪  吴剑 《吉林大学学报(地球科学版)》2019,49(6):1689-1697

青藏高原板块缝合带为印度板块和欧亚板块两大陆块的缝合区域,带区地质条件复杂,构造运动强烈。川藏线拉林铁路几乎沿雅鲁藏布江缝合带展布,高地应力问题十分突出,但目前针对板块缝合带隧道的地应力研究相对较少。本文采用空心包体法对拉林铁路沿线隧道进行了原位地应力测量,并与成兰、兰渝和锦屏等几个典型工程的地应力进行对比分析。研究表明：拉林铁路沿线隧道埋深大,构造应力突出,总体表现为最大水平主应力 > 垂直主应力 > 最小水平主应力;平均侧压系数（1.0~1.5）分布较为集中且处于较高水平;最大主应力量值大多在20~50 MPa之间,最大主应力与埋深的梯度为0.033 7 MPa/m,方向以北北西-北北东向为主。建议采用仰拱结构减小隧道墙脚处的应力集中现象。  相似文献   

张北地震序列波谱分析     

李雪英  高景春  刁桂苓  赵英萍  赵明淳 《华北地震科学》2004,22(2):6-8

采用石家庄遥测台网数字化的地震记录,选取了1998年1月～1999年12月张北震区的146条地震,分别对P波、S波作了波谱分析,求取了拐角频率、地震矩、震源半径、应力降、平均位错和波谱能量。分析了拐角频率和应力降随时间的变化趋势,并讨论了震源参数相互之间的关系。结果表明,在1999年3月11日5．6级地震之前应力降和拐角频率均出现异常,同时发现,S波对环境的变化比P波敏感,P波较稳定,且各震源参数与震级有一定相关。  相似文献   

Describing alpine lake influence on stream network temperatures: A statistical modelling approach     

Samuel P. Carlson  Geoffrey C. Poole 《水文研究》2021,35(3):e14072

Systematic variations in atmospheric heat exchange, surface residence time, and groundwater influx across montane stream networks commonly produce an increasing stream temperature trend with decreasing elevation. However, complex stream temperature profiles that differ from this common longitudinal trend also exist, suggesting that stream temperatures may be influenced by complex interactions among hydrologic and atmospheric processes. Lakes within stream networks form one potential source of temperature profile complexity due to the spatially variable contribution of lake-sourced water to stream flow. We investigated temperature profile complexity in a multi-season stream temperature dataset collected across a montane stream network containing many alpine lakes. This investigation was performed by making comparisons between multiple statistical models that used different combinations of stream and lake characteristics to represent specific hypotheses for the controls on stream temperature. The compared models included a set of models which used a topographically derived estimate of the hydrologic influence of lakes to separate and quantify the effects of stream elevation and lake source-water contributions to longitudinal stream temperature patterns. This source-water mixing model provided a parsimonious explanation for complex stream-network temperature patterns in the summer and autumn, and this approach may be further applicable to other systems where stream temperatures are influenced by multiple water sources. Simpler models that discounted lake effects were more optimal during the winter and spring, suggesting that complex patterns in stream temperature profiles may emerge and subside temporally, across seasons, in response to diversity of water temperatures from different sources.  相似文献   

黄土高原沟谷地貌发育演化研究进展与展望     

熊礼阳  汤国安 《地球信息科学学报》2020,22(4):816-826

黄土沟谷是黄土地貌中最有活力、最具变化、最富特色的对象单元,黄土高原千沟万壑的地貌形态以及触目惊心的侵蚀状态也让区域内沟谷地貌的形成、发育及演化问题成为研究中焦点及前沿性科学问题。近年来,诸多学者采用地学测年法、特征表达法、监测模拟法力图实现对黄土沟谷发育演化进程中“过去-现代-未来”的科学认知。这些研究在相当程度上丰富了黄土沟谷发育过程的认知。本文梳理了黄土高原沟谷地貌演化相关研究的现状,并从黄土高原地貌演化、黄土沟谷发育、基于DEM的沟谷信息提取与表达等研究进行了系统的回顾、梳理与分析。此外,本文提出“黄土沟道剖面群组”概念与方法,试图从新的视角审视黄土沟谷地貌发育演化过程。沟道剖面在黄土沟谷发育演化进程中传递物质能量和累积地形动力,并通过径流节点的串联实现剖面群的连接与组合,形成独特的剖面“群组”模式;该沟道剖面群组是集黄土沟谷地貌特征与过程于一体的综合信息集成体,其三维空间结构是对黄土沟谷地貌发育演化的高度抽象与映射,并可望进一步丰富黄土高原数字地形分析理论与方法体系,为黄土高原黄土地貌成因机理与空间分异格局带来创新的认识。  相似文献   

Rill flow resistance law under equilibrium bed‐load transport conditions     

Costanza Di Stefano  Alessio Nicosia  Vincenzo Pampalone  Vincenzo Palmeri  Vito Ferro 《水文研究》2019,33(9):1317-1323

In this paper, a recently deduced flow resistance equation for open channel flow was tested under equilibrium bed‐load transport conditions in a rill. First, the flow resistance equation was deduced applying dimensional analysis and the incomplete self‐similarity condition for the flow velocity distribution. Then, the following steps were carried out for developing the analysis: (a) a relationship (Equation  13 ) between the Γ function of the velocity profile, the rill slope, and the Froude number was calibrated by the available measurements by Jiang et al.; (b) a relationship (Equation  17 ) between the Γ function, the rill slope, the Shields number, and the Froude number was calibrated by the same measurements; and (c) the Darcy–Weisbach friction factor values measured by Jiang et al. were compared with those calculated by the rill flow resistance equation with Γ estimated by Equations  13 and 17 . This last comparison demonstrated that the rill flow resistance equation, in which slope and Shields number, representative of sediment transport effects, are introduced, is characterized by the lowest values of the estimate errors.  相似文献   

Conditional statistics of Reynolds shear stress in flow over 2D dunes in the presence of surface waves          下载免费PDF全文

Satya P. Ojha 《水文研究》2014,28(18):4829-4842

This study presents the analysis of the velocity fluctuations to describe the conditional statistics of Reynolds shear stress in flow over two‐dimensional dunes in the presence of surface waves of varying frequency. The flow velocity measurements over the dunes are made using a 16‐MHz 3D acoustic Doppler velocimeter. The joint probability distributions of the normalized stream‐wise and vertical velocity fluctuations at different vertical locations are calculated in the trough region of a selected dune in quasi‐steady region of the flow. Third‐order moments of the stream‐wise and vertical velocity components over one dune length are also calculated throughout the flow depth for understanding the effect of surface waves on relative contributions to the Reynolds shear stress due to the four quadrant events. The structure of instantaneous Reynolds stresses is analysed using quadrant analysis technique. It has been shown that the contributions of second and fourth quadrant events to the Reynolds shear stress increase with increase in the frequency of surface waves. In fact, the largest contribution to turbulent stresses comes from the second quadrant. The cumulant discard method is applied to describe the statistical properties of the covariance term u′w′. Conditional statistics and conditional sampling are used to compare the experimental and theoretical relative contributions to the Reynolds shear stress from the four quadrant events. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

A stress and displacement discontinuity element method for elastic transversely anisotropic rock     

A. Bobet  V. García Marín 《国际地质力学数值与分析法杂志》2014,38(18):1898-1922

The paper presents closed‐form solutions for stress and displacement influence functions for stress discontinuity (SD) and displacement discontinuity (DD) elements, for a two‐dimensional plane‐strain elastic, transversely anisotropic medium. The solutions for SD elements are based on Kelvin's problem and for DD elements on the concept of dipoles. Stress and displacement influence functions are derived for the following elements: constant SD, linear SD, constant DD, linear DD, square root DD, parabolic DD, constant DD surface, and linear DD surface elements. The formulations are incorporated into FROCK, a hybridized boundary element method code, and are validated by providing comparisons between the results from FROCK and the finite element code ABAQUS. A limited parametric analysis shows the effects of slight anisotropy on the stress field around the tip of a crack and of the orientation of the crack with respect to the axes of elastic symmetry. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Reply to comments on “Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth” (Int. J. Numer. Anal. Methods Geomech., 2019, 43 (6), 1300–1315)” by Prof. Linkov     

Haseeb Zia  Brice Lecampion 《国际地质力学数值与分析法杂志》2020,44(18):2524-2526

We reply to Prof. Linkov comments on our article entitled “Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth” (Int. J. Numer. Anal. Methods Geomech., 2019, 43 (6), 1300–1315). We present additional results indicating that both the implicit and explicit front advancement schemes are robust even in the case of a large stress contrast.  相似文献