Effects of Mudstone Particle Content on Shear Strength of a Crushed Sandstone–Mudstone Particle Mixture

The present study focuses on the shear strength, deformation, and particle crushing of sand which is mixed by crushed sandstone and mudstone particles. Two triaxial tests—one for unsaturated specimens and the other for saturated specimens—were performed, along with sieve analysis tests. Results obtained from the triaxial tests indicate that, with the increment of the mudstone particle content by weight, the angle of internal friction decreases, the cohesion increases and then decreases, and both the initial angle of shearing resistance at the atmospheric pressure and decremental angle increase and then decrease. Compared to the unsaturated specimens, the deviator stress or normalized deviator stress of the saturated specimens at the same axial stress may decrease due to the wetting action. Thus, the shear strength of the tested materials may be reduced by the wetting action. Results of sieve analysis tests indicate that the mixing of some mudstone particles into the sandstone particle mixture may reduce the amount of particle crushing, but the wetting action may increase the amount. The amount of the crushed particle may arrive at a minimum of 40% of mudstone particle content by weight.     

准噶尔盆地吉木萨尔凹陷梧桐沟组层序地层划分

准噶尔盆地吉木萨尔凹陷二叠系梧桐沟组作为一套重要的储集岩,具有良好的油气成藏前景,但对其层序划分及地层沉积样式的认识一直存在争议。在构造背景分析的基础上,结合岩芯、测井及地震资料,对研究区梧桐沟组层序地层划分及地层沉积样式研究表明,梧桐沟组沉积时期构造强度较弱,地形较为平缓,地层在全区稳定分布;中晚二叠世盆地发生造山运动,吉木萨尔凹陷东南边缘区域经过构造抬升,上部地层遭受不同程度的剥蚀,形成了现今"底平顶削"的地层样式。以凹陷中部少数地层保存较全的井的地层叠加样式分析为基础,通过井-震结合识别不同类型界面,特别是最大湖泛面,建立了区域层序地层格架,即梧桐沟组为一个完整的长期基准面旋回(三级层序),并在其内部识别出5个中期旋回。梧桐沟组地层在不同的层序发育时期表现出不同的旋回叠加样式:下段沉积时期,即最大湖泛面以下,随着可容纳空间的增大,地层表现为明显的退积叠加样式;上段沉积时期,即最大湖泛面以上,随着可容纳空间的减小,地层表现为明显的进积叠加样式,符合沉积物体积分配原理。     

南海中建南盆地构造样式分析

中建南盆地是发育于南海西部陆缘我国传统疆界线附近的新生代沉积盆地,大部分区域位于我国传统疆界线内。在对盆地近万千米多道地震资料综合分析解释的基础上,对盆地的主要构造样式以及它们与油气的关系进行了分析,结果表明,盆地分布面积广,沉积厚度大,油气前景良好。盆地是属于早期断陷、后期经走滑改造而成的复合型盆地,其构造演化经历了3个阶段,不同的阶段发育不同的构造样式:早期为断陷阶段,伸展型构造样式发育;中期为断坳—压扭或走滑反转阶段,产生走滑或压扭性构造样式;晚期为区域沉降阶段,以垂向沉积为主,无明显的构造样式发育。     

Early Cretaceous deformation in the southern Tashkorgan region: Implications for the tectonic evolution of the northeastern Pamir

The Pamir Plateau comprises a series of crustal fragments that successively accreted to the Eurasian margin preceded the India-Asia collision, is an ideal place to study the Mesozoic tectonics. The authors investigate the southern Tashkorgan area, northeastern Pamir Plateau, where Mesozoic metamorphic and igneous rocks are exposed. New structural and biotite ⁴⁰Ar-³⁹Ar age data are presented. Two stages of intense deformation in the metamorphic rocks are identified, which are unconformably covered by the Early Cretaceous sediment. Two high-grade metamorphic rocks yielding 128.4 ± 0.8 Ma and 144.5 ± 0.9 Ma ⁴⁰Ar-³⁹Ar ages indicate that the samples experienced an Early Cretaceous cooling event. Combined with previous studies, it is proposed that the Early Cretaceous tectonic records in the southern Tashkorgan region are associated with Andean-style orogenesis. They are the results of the flat/low-angle subduction of the Neotethyan oceanic lithosphere.©2021 China Geology Editorial Office.     

T形短肢剪力墙静力性能有限元仿真分析

利用有限元分析软件ANSYS,首先采用其中三维实体单元SOLID65建立了T形短肢剪力墙有限元分析模型,从弹性到混凝土开裂直至破坏的全过程进行了仿真试验分析。分析了影响短肢剪力墙受力的几种因素:混凝土强度等级、配筋率、轴压比、墙肢截面高厚比对短肢剪力墙承载能力、变形能力及延性的影响,剖析了短肢剪力墙破坏过程及其原因。比较真实的反映了短肢剪力墙在轴压力和逐步加载侧向力共同作用下的响应。试验结果表明:增加混凝土等级和轴压比能提高试件的开裂、屈服和极限荷载,但应综合考虑其与变形能力、延性的关系。截面配筋率具有其特殊性,配筋率在1.4%1.6%之间时试件的承载能力、变形能力及延性较好。墙肢截面高厚比是不稳定因素但在高厚比为6.57.1时,延性及变形能力较强。     

Cascaded image analysis for dynamic crack detection in material testing

Concrete probes in civil engineering material testing often show fissures or hairline-cracks. These cracks develop dynamically. Starting at a width of a few microns, they usually cannot be detected visually or in an image of a camera imaging the whole probe. Conventional image analysis techniques will detect fissures only if they show a width in the order of one pixel. To be able to detect and measure fissures with a width of a fraction of a pixel at an early stage of their development, a cascaded image analysis approach has been developed, implemented and tested. The basic idea of the approach is to detect discontinuities in dense surface deformation vector fields. These deformation vector fields between consecutive stereo image pairs, which are generated by cross correlation or least squares matching, show a precision in the order of 1/50 pixel. Hairline-cracks can be detected and measured by applying edge detection techniques such as a Sobel operator to the results of the image matching process. Cracks will show up as linear discontinuities in the deformation vector field and can be vectorized by edge chaining. In practical tests of the method, cracks with a width of 1/20 pixel could be detected, and their width could be determined at a precision of 1/50 pixel.     

营口-潍坊断裂带新生代运动学特征

营口-潍坊断裂带在新生代时期对渤海湾盆地东部构造、沉积及油气成藏规律等方面具有重要影响和控制作用.依据大量实际地震资料,从剖面上识别出了花状构造、丝带效应、反转构造等营口-潍坊断裂带新生代时期走滑活动的标志,在平面上识别出了4种组合构造样式,在此基础上,应用拉分盆地走滑量计算的理论模型,对营口-潍坊断裂带新生代时期的走滑位移量进行了初步估算,认为营口-潍坊断裂带在新生代时期具右旋走滑活动特征,其主要走滑活动表现为3期,分别为始新世早期、渐新世早-中期和上新世晚期-第四纪,新生代累计右旋走滑位移量约为10～20 km.     

珠江口盆地珠三坳陷层序地层样式分析

珠江口盆地珠三坳陷是一个典型的箕状断陷盆地,其层序地层格架受到主干断裂特别是珠三南断裂的强烈控制。由于珠三南断裂活动的差异性,盆地东部、中部和西部表现为不同的格架样式。并据此划分出坳陷内的3种典型层序样式,分别是缓坡型、断控陡坡型和断阶型层序样式。文昌A凹陷与阳江低凸起过渡的斜坡区和文昌B凹陷与琼海低凸起过渡区为具有坡折的缓坡背景,发育缓坡坡折型层序样式,发育斜坡扇、盆底扇、低位楔。珠三南断裂等主干断裂下降盘发育断控陡坡带层序样式,在珠三南断裂中部地区,发育断阶型层序样式。     

船载物探电子设备的接地问题及解决方案

船栽物探电子设备,是一个电气结合复杂的数据采集记录系统.各系统电子线路因船舶配电方式、工作环境的特殊性,其接地很重要,但容易被忽视.而接地处理不当,在使用时会受到噪声干扰、振荡;或造成仪器的输出榆入电路损坏,不能正常工作.更严重地甚至机壳漏电,危及人身安全.船栽物探电子设备接地问题.可分为"接地保护"和"接地故障"."接地保护"是将电气设备的金属外壳、支架和电缆的护套与大地等单位的金属船体(船壳)作永久性良好的电气连接,它分为保护接地和功能接地."接地故障"是指因设备不正确接地或由于绝缘层的破损、老化及环境恶劣引起绝缘电阻低下或者接地干扰等问题.文中从船载物探电子设备的使用特性出发.讨论在实际接地处理中出现问题的原因,分析了各种接地干扰的原理.并提出了相应的解决方案,对于船栽物探电子设备的实际安装应用有一定的指导意义.     

Damage assessment for submarine photoelectric composite cable under anchor impact

The impact of dropped anchor on submarine photoelectric composite cables may possibly cause electrical faults, i.e. electricity and optical signal transmission failure. In order to study the impact capacity and structural impact failure mechanism, a test setup is designed originally to examine the structural and functional integrity. A detailed finite element model (FEM) is created, considering material nonlinearity and component interaction. A parametric analysis has been performed to predict the deformation of components and impact forces, under different impact velocities and collision directions. Relationships between the armor layer indentation rate and that of internal power and optical units are achieved. The impact deformation of internal entities can be evaluated intuitively by armor layer indentation. The proposed experimental and numerical methods are well correlated, suitable to assess the impact capacity of subsea power cables and assist the protection design of subsea power cables in engineering.