走滑断裂带中挤压阶区内部剪切构造初探

野外地质调查和航片立体镜下解译发现,小江断裂带北段蒙姑和东支大营盘两个挤压阶区内部发育有剪切构造,它们在地表主要表现为断裂槽地、断层陡坎、地裂缝等。挤压阶区内部剪切构造和拉张阶区内部剪切构造一样,是阶区形成后,随着走滑断裂的进一步活动而形成的新生性构造     

红砂岩高陡岩质边坡稳定性分析及治理

充分利用边坡失稳前自身抗滑能力进行高陡边坡治理，结合工程实例，提出了主动性公路边坡治理的思路。分别利用极限平衡法和有限元数值法，综合考虑了两种方法的优缺点，对红砂岩高陡边坡进行了全面的稳定性分析，并针对性地提出了经济合理的治理方案。     

尼日尔Termit盆地古近系构造样式及其对油气聚集的控制作用

尼日尔Termit盆地主要发育早白垩世和始新世-渐新世两个裂陷旋回,其起源于不同的动力学背景和运动学机制,相应表现出不同的盆地性质。其中古近纪始新世-渐新世第二裂陷旋回受区域挤压应力环境下的非洲板块内部局部应力释放控制,具有逃逸盆地的性质,在盆地内部表现为典型走滑伸展特征。该旋回在第一期NW-SE控盆断裂基础上发育了NNW-SSE断裂体系,盆地整体呈现地堑地垒和半地堑结构,北部为双断结构地堑,南部为西断东超多米诺半地堑结构。古近系断裂的斜向拉张作用形成了大量雁列式正断层,以软连接方式相连,在二级构造单元内发育了大量构造调节带,分为同向型、对向型和背向型3大类,以同向叠覆型、对向平行型和背向叠覆型为主,成为Termit盆地最主要的构造调节带样式。古近纪始新世-渐新世第二裂陷旋回及其构造样式控制了盆地沉积体系,在始新世Sokor1初始裂陷期形成了三角洲湖泊沉积体系、渐新世-早中新世Sokor2深陷期沉积了湖相泥岩,形成了盆地主力储盖组合。同时,该旋回的构造调节作用形成了大量断块和断鼻/断背斜构造,成为Termit盆地的主要圈闭类型。渐新世-早中新世的深陷期导致断层沟通白垩系成熟烃源岩,在盆地内发生广泛的垂向和侧向运移,该时期断层的活动强度决定了古近系油气分布和富集程度。Sokor1和Sokor2段中下部岩性圈闭及Sokor2段成藏组合是Termit盆地的下步勘探领域。     

刚性挡土墙后三维被动滑裂面的模型试验

针对无黏性土体,采用模型试验的方法,研究平移模式下刚性挡土墙后被动破坏滑裂面的空间形态。自主设计一种模型试验装置,重复开展6次试验,通过记录挡土墙后土体中预埋脆性玻璃条断裂的空间坐标,复原土体发生滑动的位置,绘制出挡土墙后滑裂面的三维形态图。试验结果表明：挡土墙后滑裂面具有明显的三维效应;挡土墙宽度内滑裂面纵向高度呈先缓慢增高后近似直线增高的曲面,初始破裂角度为9°,平均破裂角为26°,朗肯土压力理论的破裂角为28°;最大纵向破裂面长度为1.8倍挡土墙高度,与经典土压力理论的平面假定基本一致;滑裂面均有一定的横向扩展,主平面投影以初始扩散角约45°的斜线往外扩展,距离挡土墙最远处是宽度为0.7倍挡土墙宽度的水平线,斜线与水平线之间以半径为挡土墙宽度的圆弧过渡连接。研究结果为分析土体被动破坏的滑裂面空间形态提供了试验依据。     

GPS多路径效应实例计算与分析

本文讨论了一个GPS伪距多路径值计算及其频谱分析的方法。文中首先介绍了GPS多路径试验测量和观测数据采集的程序。然后探测和修复周跳、再利用伪距多路径计算公式,获得GPS测量中的伪距多路径值。实例证明该方法有效地计算出了伪距多路径值。     

地震作用对琼州海峡海缆路由区海底稳定性影向的分析

以琼州海峡的北海—临高段海缆路由为例,利用计算对比的方法,分析了地震作用下,路由区3m以浅海底土液化或滑移的可能性,评价了路由区海底的稳定性。结果发现,在地震烈度为Ⅶ度的地震作用下,砂性土海底的地震剪应力平均值(0.86kPa,1.72kPa和2.57kPa)小于砂性土的液化剪应力(1.60kPa,3.20kPa和4.81kPa);粘性土海底的地震剪应力平均值(1.25kPa,2.49kPa和3.74kPa)小于粘性土的抗滑剪应力平均值(4.07kPa,4.61kPa和4.49kPa),路由区海底稳定性良好;在地震烈度为Ⅷ度的地震作用下,砂性土海底的地震剪应力平均值(1.73kPa,3.45kPa和5.12kPa)大于砂性土的液化剪应力;粘性土海底的地震剪应力平均值(2.49kPa,4.98kPa和7.47kPa)除表层外,大于粘性土的抗滑剪应力,路由区海底会发生失稳破坏。     

Ultrahigh temperature deformation microstructures in felsic granulites of the Napier Complex, Antarctica

Detailed electron microscope and microstructural analysis of two ultrahigh temperature felsic granulites from Tonagh Island, Napier Complex, Antarctica show deformation microstructures produced at  1000 °C at 8–10 kbar. High temperature orthopyroxene (Al 7 wt.% and  11 wt.%), exhibits crystallographic preferred orientation (CPO) and frequent subgrain boundaries which point to dislocation creep as the dominating deformation mechanism within opx. Two different main slip systems are observed: in opx bands with exclusively opx grains containing subgrain boundaries with traces parallel to [010] and a strong coupling of low angle misorientations (2.5°–5°) with rotation axes parallel to [010] the dominating slip system is (100)[001]. Isolated opx grains and grain clusters of 2–5 grains embedded in a qtz–fsp matrix show an additional slip system of (010)[001]. The latter slip system is harder to activate. We suggest that differences in the activation of these slip systems is a result of higher differential stresses imposed onto the isolated opx grains and grain clusters. In contrast to opx, large qtz grains (up to 200 μm) show random crystallographic orientation. This together with their elongate and cuspate shape and the lack of systematic in the rotation axes associated with the subgrain boundaries is consistent with diffusion creep as the primary deformation mechanism in quartz.Our first time detailed microstructural observations of ultrahigh temperature and medium to high pressure granulites and their interpretation in terms of active deformation mechanisms give some insight into the type of rheology that can be expect at lower crustal conditions. If qtz is the mineral phase governing the rock rheology, Newtonian flow behaviour is expected and only low differential stress can be supported. However, if the stress supporting mineral phase is opx, the flow law resulting from dislocation creep will govern the rheology of the rock unit; hence, an exponential relationship between stress and strain rate is to be expected.     

A numerical method for the study of shear band propagation in soft rocks

This paper investigates the possibility of interpreting progressive shear failure in hard soils and soft rocks as the result of shear propagation of a pre‐existing natural defect. This is done through the application of the principles of fracture mechanics, a slip‐weakening model (SWM) being used to simulate the non‐linear zone at the tips of the discontinuity. A numerical implementation of the SWM in a computation method based on the boundary element technique of the displacement discontinuity method (DDM) is presented. The crack and the non‐linear zone at the advancing tip are represented through a set of elements, where the displacement discontinuity (DD) in the tangential direction is determined on the basis of a friction law. A residual friction angle is assumed on the crack elements. Shear resistance decreases on elements in the non‐linear zone from a peak value at the tip, which is characteristic of intact material, to the residual value. The simulation of a uniaxial compressive test in plane strain conditions is carried out to exemplify the numerical methodology. The results emphasize the role played by the critical DD on the mechanical behaviour of the specimen. A validation of the model is shown through the back analysis of some experimental observations. The results of this back analysis show that a non‐linear fracture mechanics approach seems very promising to simulate experimental results, in particular with regards to the shear band evolution pattern. Copyright © 2009 John Wiley & Sons, Ltd.     

陕北奥陶纪盐盆的区域成矿地质条件分析

本文以鄂尔多斯盆地陕北奥陶纪岩盐为主要研究对象,在深入分析以往岩盐的成因机制和充分利用前人的研究资料基础上,从区域古气候、古地理、古构造和岩相古地理方面综合分析认为,奥陶纪时期,陕北盐盆能够发育巨厚岩盐,并且岩盐沉积时的卤水达到钾石盐至光卤石的阶段,是由有利于成盐的干旱古气候条件,有利于蒸发岩发育的半封闭的区域构造、地质条件,以及区域上有利于氯化物盐类迁移富集的预备盆地发育的区域岩相古地理条件共同作用的结果。     

新型旋转减冲装置对桩基局部冲刷防护试验研究

为减轻海上风电单桩基础周围局部冲刷对其结构安全的影响,提出了一种新型旋转减冲装置。在波流水槽中开展物理模型试验,改变波流条件、装置安装高度、安装距离,记录桩周冲刷发展历时,运用激光地形仪扫描冲刷坑形态,分析各工况下冲刷坑形态差异,验证装置不同安装距离、安装高度下的冲刷防护效果,提出了不同安装位置下的防护效率公式。结果表明：新型旋转减冲装置具有较好的冲刷防护效果,本试验工况下,桩周最大冲刷深度可减小44%左右。装置安装距离对冲刷防护效果影响较小,波流作用下的冲刷防护效果受装置安装高度影响显著,冲刷防护效果随装置安装高度的增加而减弱。