南安集海-南玛纳斯背斜的构造分析及其横向转换研究     

简高明  陈伟  姜中卫  王兵  肖力新 《新疆地质》2006,24(3):249-252

南安集海背斜和南玛纳斯背斜属于准噶尔南缘山前中西段第一排构造带,构造变形异常强烈,呈典型的堆跺式双重构造.通过应用断层相关褶皱的构造几何分析方法,用计算机对南安集海-南玛纳斯背斜带内的基干地震剖面进行了构造解析,南玛纳斯背斜是在霍-玛-吐断裂上叠加一堆跺式双重构造组成,向西南玛纳斯背斜上的堆跺式双重构造逐渐消失,同时霍-玛-吐断裂位移量逐渐转换成反向逆冲断层,形成南安集海背斜的复合型构造三角楔.通过构造解析,弄清了它们在三维空间中的过渡转换关系,对后继的南缘山前构造带的勘探开发具有参考意义.  相似文献   

Assessment of the collapse mechanisms of tufa deposits     

Nihat Dipova  Vedat Doyuran   《Engineering Geology》2006,83(4):332-342

This research assesses the collapse mechanisms of tufa deposits. The city of Antalya, located on the Mediterranean coast of Turkey, has been settled on tufa deposits. By the end of 1980s, the area behind the tufa cliffs became the site of high-rise residential buildings. Some of these buildings have suffered from foundation instabilities, which have given rise to cracking and fissuring of the walls, and overall tilting. The collapsible behaviour upon loading and/or wetting of some tufa deposits has caused foundation settlement.

Voids, bonding of grains and grain properties of the collapsible tufa were investigated using optical and scanning electron microscopes. Our studies indicate that the collapse behaviour of tufa is affected mainly by depositional environment and microfabric. Laboratory tests have been performed in order to determine the index properties and the collapse potential of tufa samples. Young tufa deposits near the surface are weakly bonded with thin films of carbonate cement, giving rise to high void ratios. Analysis of geotechnical parameters has shown that the collapse potential of tufa is closely related to the natural void ratio and the amount of cement binding the grains.  相似文献   

Turbulence modeling of compound open-channel flows with and without vegetation on the floodplain using the Reynolds stress model     

Hyeongsik Kang  Sung-Uk Choi 《Advances in water resources》2006

A Reynolds stress model for the numerical simulation of compound open-channel flows with vegetation on the floodplain is described. The Reynolds stress model consists of various sub-models such as Speziale et al.’s model, Mellor and Herring’s model, and Rotta’s model for the pressure–strain correlation term, the turbulent diffusion term, and the dissipation term, respectively. For validation of the model, plain compound open-channel flows are simulated. The computed results were compared with measured data by [Tominaga A, Nezu I. Turbulent structure in compound open-channel flows. J Hydraul Eng, ASCE 1991;117(1):21–41] and the results show that the Reynolds stress model successfully simulates the mean flow and turbulence structure of plain compound channel flows. The model was then applied to compound open-channel flows with vegetated floodplains. Good agreement between the simulated results and data from an algebraic stress model by [Naot D, Nezu I, Nakagawa H. Hydrodynamic behavior of partly vegetated open channels. J Hydraul Eng, ASCE 1996;122(11):625–33] was found. However, it was shown that the RSM is capable of predicting the velocity dip and lateral shift in the maximum streamwise velocity, which were not observed in the data from algebraic stress modeling. Finally, a depth-averaged analysis of the streamwise momentum equation was performed to investigate the lateral momentum transfer in compound channel flows with vegetated floodplains. Compared with components by the secondary currents and Reynolds stress, the drag force due to the presence of vegetation appears to be a factor in reducing the bottom shear stress in both main channel and floodplain.  相似文献   

1995年云南孟连西7.3级地震前震序列特征及其与主震的关系     

刘祖荫  钱晓东  张俊伟 《湖南地质》1998,(4)

在分析１９９５年云南孟连西７３级地震的前震序列时,发现跟踪最大前震６２级的余震序列中,有一组较大震级的地震呈现出随时间的增长不断线性递增的特点,这种特点在云南其他震例中也曾多次出现过。利用修正的大森公式ｎ（ｔ）＝ｋ／（ｔ＋ｃ）ｐ拟合该序列,在获得的参数重新构造的频度－线性化时间坐标中,这一组地震显示出与海城前震序列随时间变化震级出现非线性增强的共同特征。采用表征物质加速应变而失稳的方程ｄ（∑Ｍ０１／２）／ｄｔ＝ｃ／（ｔｍ－ｔ）ｎ,对孟连西前震序列多方面进行跟踪定量分析,预测主震的发生时间平均比实发时间仅推迟２６ｍｉｎ,震级相差０１７级。  相似文献   

钻孔桩基础的一个失败实例   总被引：2，自引：1，他引：1  

杨世忠  赵晓炯 《地质与勘探》1998,34(2):55-57

列举了一个显然是按照正常施工过程步骤成桩的败例。以对整个成桩过程全面调查和详细试桩结果为基础,对该桩质量所存在的问题作了深入细致分析。提出了改进挖斗体结构、改善无循环钻孔灌注桩成孔工艺,对混凝土各个环节质量控制手段也提出建议。  相似文献   

浅层地震反射波法在某些特殊工程地质中的应用效果     

刘基 《铀矿地质》1997,13(6):370-374

本文通过应用浅震反射波法解决浅部滑坡体、孤石、基桩持力层等特殊工程地质问题，阐明浅震反射波法在工程勘察中具有良好的应用效果及应用前景。  相似文献   

Chlorinated Hydrocarbons in Sediments of the Elbe Catchment Area – Analytical Methods and Status of Pollution     

J. Gandraß  M. Zoll 《洁净——土壤、空气、水》1996,24(5):212-217

A survey was conducted to determine the status of pollution of surficial sediments in the Elbe catchment area (Germany, Czech Republic) for the period 1992 to 1994. Chlorinated benzenes, PCBs, DDT and its metabolites, and HCH isomers were determined by GC/ECD following a simultaneous steam distillation-extraction procedure. Most of the investigated compounds showed increased concentration levels in sections of the Elbe or its main tributaries exceeding the target value II (quality criteria ARGE Elbe). Patterns of chlorinated hydrocarbons could be traced back from the Elbe into tributaries, and in some cases, links between patterns and inputs or long-term effects of former chemical production sites were supposed.  相似文献   

地下采动顺向缓倾构造山坡的滑移机理     

林叔中  胡广韬  赵法锁  毛彦龙 《地球科学与环境学报》1993,(Z2)

采空区地表山体侧向变动,不同于一般天然山坡,也与采空区一般上覆岩层的变形破坏有异;它是二者复合机理的效应。本文在分析考察了毗邻电厂的横山顺倾构造山体、剖析了地下采空情况认为:山体侧向变动中,软弱夹层有决定性作用,变动范围、速率和规模与地下采空有关;并利用地质力学模型试验和数值模拟,探索了采动引起山体应力场及变动规律。结果表明,山体岩层的变形、位移、破坏、由直接顶板向地表发展,采空坍陷诱发了软弱夹层的蠕滑,则产生山体侧向滑移;电厂区地表隆起变形是山体侧向滑移挤压地基土的反映。通过现场实际调研、变形观测资料分析与数值模拟和模型试验的对比研究,提出了“坍落拱梁”的成生效应、挤压蠕滑效应、失稳效应;揭露了顺倾构造山体在采空影响下,具有地表、地下的“复合临空面”的“复合应力场”中“复合变动”的“复合机理”;并提出这种山体侧向变动机理的典型地质模式,借以论证山体稳定性。  相似文献   

Cones to model foundation vibrations: incompressible soil and axi-symmetric embedment of arbitrary shape     

John P. Wolf  Andrew J. Deeks   《Soil Dynamics and Earthquake Engineering》2004,24(12):963-978

The recently streamlined strength-of-materials approach using cones to calculate vibrations of foundations embedded in layered half-spaces and full-spaces is applied to incompressible and nearly-incompressible soil and to axi-symmetric embedments of arbitrary shape. For incompressible soil the axial-wave velocity in the cones is limited to twice the shear-wave velocity and a trapped mass for the vertical motion and a trapped mass moment of inertia for the rocking motion moving as a rigid body with the under-most disk of an embedded foundation are introduced. In the case of a fully embedded foundation, a mass and a mass moment of inertia are also assigned to the upper-most disk. For an axi-symmetric embedment of arbitrary shape, the disks have varying radii. No modifications to the formulation are, however, required. For these two extensions the strength-of-materials approach using cones leads to the same sufficient engineering accuracy as is achieved in other more conventional cases. This is demonstrated in a vast study. Thus the same other advantages also apply: physical insight with conceptual clarity, simplicity and sufficient generality.  相似文献   

南京地铁小行车辆段软基处理方法选择     

镇木生  刘黎明 《江苏地质》2003,27(2):107-109

南京地铁小行车辆基地在软土地基处理中，根据工程地质条件，将原设计的粉喷桩及时调整为深搅桩，既保证了施工质量，又节省了大量资金。该工程实践表明，在工程施工中，根据施工条件与施工效果，及时调整施工方案是十分重要和必要的。  相似文献