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291.
横江韧性剪切带与金矿关系密切。该带中央为揉流褶皱带,往两侧至边缘依次出现鞘褶皱、a型褶皱、b型褶皱。带内发育的拉伸线理方向与剪切带走向近于垂直,旋转石香肠指示剪切运动方向为北西一南东向右型剪切,表明本带为韧性推覆剪切带。 相似文献
292.
胶南隆起北缘中段左行正滑韧性剪切带研究 总被引:2,自引:0,他引:2
在详细的野外地质填图的基础上,通过各种尺度的构造研究和系统的应变测量,确定了胶南隆起北缘中段的大型左行正滑韧性剪切带的存在及其延展范围,并提出了确定韧性剪切带边界的构造几何学准则。研究了该韧性剪切带的几何学和运动学特征及变形机制,估算了其剪切位移量(大于7557m)及形成时的差异应力(σ_1-σ_3=94.6~114.4MPa)。该韧性剪切带可以作为胶南隆起的北部边界,但不是重要的板块碰撞边界。 相似文献
293.
The speedv, especially the problem whether super S-wave velocity in the classical model (linear elasticity fracture mechanics) exists,
of spontaneous propagation of a shear fault is investigated theoretically. An in-plane shear crack propagating in the crack
plane is taken as the model of the shear fault. The results obtained firstly by Kostrov (1975) is extended from sub-Rayleigh
wave velocity to super S-wave velocity, and the analytical expression for the stress intensity factorK
2 in the case ofα>v>β is derived. It is proved that for Poisson mediumK
2 is positive and real in the velocity range (β, 1.70β). This demonstrates that (β, 1.70β) is the velocity range which fulfils the conditions for spontaneous crack propagation. The existence, convergence and positiveness
or negativeness ofK
2 forv in individual sections are examined, and it is found that for an in-plane shear crack: 1. There are three sections forv, i.e., [0.v
R], (β, 1.70β), andα, respectively, and 2. There are two physically reasonable sections forv, the first is [v
R, β], and the second is [1.70β, α]. These two forbidden sections behave as barriers to fault propagation.
The analytical expressions derived in this paper are not only suitable to classical model, but also to the other derivative
models (e. g., the slip-weakening model and the renomalization model etc.). The model considered in this paper is more realistic
than the static model employed by previous authors.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica, 15, 9–14, 1993. 相似文献
294.
Analysis of the influence of Taihu Lake and the urban heat islands on the local circulation in the Yangtze Delta 总被引:6,自引:0,他引:6
The influences of human activities on regional climate and weather are tremendous. The re-gional temperature and the distributing of wind field are influenced, whereas the precipitation in-tensity and the spatial and temporal distribution of the precipita… 相似文献
295.
分析了现有起动标准的不足之处。在制定起动标准时,不但要考虑水流条件,还必须考虑泥沙颗粒在床面的相对位置。对同一粒径的泥沙颗粒,其起动条件不是一个常量,而是位于一个区间,它随颗粒在床面的相对暴露度而变化。根据力学原理,推导了泥沙颗粒起动时的临界无量纲切应力公式,并对其系数取值进行了理论计算。计算结果表明,对同一粒径、在同一起动状态下,泥沙颗粒的起动临界条件并非一个常量。并从理论上分析得到了临界值的范围,对个别及少量起动,其无量纲临界切应力为0.021~0.042及0.041~0.062。 相似文献
296.
297.
The feasibility and efficiency of a seismic retrofit solution for existing reinforced concrete frame systems, designed before the introduction of modern seismic‐oriented design codes in the mid 1970s, is conceptually presented and experimentally investigated. A diagonal metallic haunch system is introduced at the beam–column connections to protect the joint panel zone from extensive damage and brittle shear mechanisms, while inverting the hierarchy of strength within the beam–column subassemblies and forming a plastic hinge in the beam. A complete step‐by‐step design procedure is suggested for the proposed retrofit strategy to achieve the desired reversal of strength hierarchy. Analytical formulations of the internal force flow at the beam–column‐joint level are derived for the retrofitted joints. The study is particularly focused on exterior beam–column joints, since it is recognized that they are the most vulnerable, due to their lack of a reliable joint shear transfer mechanism. Results from an experimental program carried out to validate the concept and the design procedure are also presented. The program consisted of quasi‐static cyclic tests on four exterior, ? scaled, beam–column joint subassemblies, typical of pre‐1970 construction practice using plain round bars with end‐hooks, with limited joint transverse reinforcement and detailed without capacity design considerations. The first (control specimen) emulated the as‐built connection while the three others incorporated the proposed retrofitted configurations. The experimental results demonstrated the effectiveness of the proposed solution for upgrading non‐seismically designed RC frames and also confirmed the applicability of the proposed design procedure and of the analytical derivations. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
298.
This study investigates the interaction of the vertical velocity v and the streamwise velocity u in a gradually accelerating flow. The analytical result shows that the momentum of uv driven by the mean velocities in a non-uniform flow is not negligible. This additional momentum directly results in the concave profiles of Reynolds shear stress in gradually accelerating flows, a departure from the expected linear profile. Consequently, this momentum causes the maximum velocity to be located below the free surface, i.e., the dip-phenomenon. This paper investigated the interactions of the Reynolds shear stress, non-zero vertical velocity and dip-phenomenon, it is found that the non-zero vertical velocity causes the dip-phenomenon. The approach is tested using the experimental data of Song and others, and good agreements between the predicted and measured velocity profiles have been achieved. 相似文献
299.
基于美国马里兰大学提供的海洋同化(SODA)月平均资料,用个例和合成分析方法,剖析了两类ENSO事件赤道太平洋海温异常演变特征。结果指出,东部型ENSO事件的初始海温异常源来自赤道西太平洋次表层,海温异常中心沿气候温跃层向东向上传送,至赤道东太平洋表层形成ENSO事件。东部型ENSO冷暖事件互为初始场,在形成某一位相的ENSO事件的过程中也同时为相反位相的ENSO事件准备条件。中部型ENSO事件的初始海温异常源出现在赤道中太平洋次表层,海温异常中心沿气候温跃层向东向上传送至赤道中东太平洋表层形成ENSO事件。中部型ENSO事件多在前次事件减弱中断后出现。 相似文献
300.
节理裂隙边坡锚注加固机制及特性研究 总被引:6,自引:0,他引:6
本文通过对节理裂隙边坡锚注加固模型的力学推导,得出锚注加固工法可以提高岩石边坡弱面抗剪强度和抗剪刚度的结论;指出锚注结构可以充分发挥锚杆和注浆体各自的材料潜能,从而避免锚杆单独作用所存在的弊端;结合某高速公路边坡加固工程,阐述了锚注加固工法的技术特点及工艺流程,指明压力注浆可以针对边坡岩体的薄弱环节,直接进行有效的处理,使边坡的稳定性得以提高,并就边坡锚注加固施工中存在的技术问题,提出相应的处理措施。 相似文献