超高压变质岩的塑性流变学   总被引：1，自引：1，他引：0  

钟增球  索书田 《现代地质》2007,21(2):203-212

岩石流变作用是大陆造山作用的基本特征,超高压岩石的形成和折返过程也是大陆深俯冲带内物质的复杂流变过程。要深入理解大陆造山带的造山作用和大陆壳岩石的深俯冲和折返动力学过程,必须对大陆地壳及地幔岩石的流变学进行深入研究。岩石圈流变学的主要研究内容主要包括流变学分层性、变形分解和应变局部化及大陆壳岩石部分熔融作用的流变学效应等。应用岩石圈流变学的基本原理和方法,分析了大别-苏鲁超高压变质带中超高压变质岩的塑性流变特点,探讨了超高压变质岩形成和折返过程的塑性流变学。  相似文献   

大理岩破坏阶段Biot系数研究   总被引：3，自引：1，他引：3  

胡大伟  周辉  谢守益  张凯  邵建富  冯夏庭 《岩土力学》2009,30(12):3727-3732

在流固耦合研究中经常采用有效应力原理,Biot系数的确定为其中困难之一。为了研究含裂纹大理岩中Biot系数演化规律,在三轴压缩塑性变形后期阶段的不同轴向变形条件下,进行轴向压力加卸载循环;并在轴向压力卸载末期对岩样施加孔隙水压力。通过记录试样的变形,在Shao提出的Biot系数计算方法的基础上,计算轴向和侧向Biot系数。得到了不同围压条件下轴向和侧向Biot系数随轴向变形的演化规律,并对此进行了深入分析。结果表明：（1）Biot系数表现为各向异性,三轴压缩试验时,试样中大部分裂纹沿最大正应力方向扩展,是造成这种现象的直接原因;（2）轴向和侧向Biot系数随着轴向变形的增大而增大,轴向变形的增大引起岩样中裂纹扩展,导致Biot系数增大;（3）低围压条件下轴向和侧向Biot系数均比高围压条件下的值大,这是由于破坏方式不同引起的。  相似文献   

厦门海底隧道施工方案优化研究     

周宇 《岩土力学》2006,27(Z1):421-425

基于数值模拟方法,对厦门海底隧道施工进行优化分析。在侧压力系数为0.6和0.9情况下,首先针对3种常用施工方法——全断面开挖法、上下台阶法和台阶分部开挖法进行计算分析,通过比较隧道洞周关键点位移及洞周塑性区分布,得到全断面开挖对围岩的扰动较小;然后,通过计算分析不同台阶长度对隧道的稳定性的影响,得到上下台阶开挖台阶步距为10 m左右较为合理的结论,对海底隧道的施工具有一定的指导意义。  相似文献   

对现行规范以液性指数IL确定极限端阻力标准值qpk的质疑   总被引：4，自引：0，他引：4  

刘亚群  林长青  李海波  周青春 《岩土力学》2003,24(2):246-248

通过对某工程单桩极限承载力标准值不满足设计要求的原因进行深入分析,指出持力层土所含的高岭土浸水软化,当受到荷载作用时,在桩端周围形成塑性剪切滑移面,产生局部剪切破坏,大大降低了桩端持力层土的极限端阻力标准值qpk,从而指出现行《建筑桩基技术规范》(JGJ 94-94)[1]仅以液性指数IL,确定极限端阻力标准值qpk值存在不足,宜综合压缩模量Es和孔隙比e而定。  相似文献   

洞室跨度对围岩分类影响探讨   总被引：4，自引：0，他引：4  

周建民  金丰年  王斌  赵佩胜 《岩土力学》2005,26(Z1):303-305

随着大跨度地下工程日益增多,跨度对围岩分类或岩体质量分级的影响越来越受到人们的重视。通过对节理岩体中洞室支护代价、塑性松动区半径和岩体宏观力学参数尺寸效应的分析,根据洞室跨度增加导致围岩稳定程度降低的情况,强调重视围岩分类中洞室跨度因素的影响,并建议通过研究岩体强度等物理力学指标的尺寸效应,在围岩分类中科学地考虑洞室跨度的影响。  相似文献   

A coupled one‐dimensional viscoelastic–plastic model for aquitard consolidation caused by hydraulic head variations in aquifers          下载免费PDF全文

T.‐L. Tsai 《水文研究》2015,29(22):4779-4793

Accurate and practical calculation of aquitard consolidation is required for a reliable analysis of land subsidence caused by groundwater overexploitation in a multilayered aquifer system because aquitards are generally more compressible than aquifers are. This study proposes a coupled one‐dimensional viscoelastic–plastic consolidation model that considers the combined effect of changes in soil parameters and body force to simulate aquitard consolidation caused by hydraulic head variations in neighbouring aquifers. The proposed model uses variable total stress and simultaneously solves hydraulic head and vertical soil displacement. The constitutive relation based on the Voigt model with different elastic moduli of the spring in normally consolidated and overconsolidated soils is used to describe the viscoelastic–plastic deformation mechanism of aquitards. In addition, the proposed model considers the combined effect of variations in hydraulic conductivity, elastic moduli, and body force on the calculation of aquitard consolidation. Three hypothetical scenarios with various hydraulic head variations in aquifers are used to examine the coupled one‐dimensional viscoelastic–plastic consolidation model. The results show that neglecting plasticity and viscosity of soil causes aquitard consolidation to be respectively underestimated and overestimated. In addition, ignoring body force variation underestimates aquitard consolidation, whereas neglecting soil parameters variation overestimates aquitard consolidation. Two real case scenarios are also studied to further demonstrate the applicability of the coupled one‐dimensional viscoelastic–plastic consolidation model. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

变形稳定理论在盐岩储气库优化设计中的应用     

邓检强  吕庆超  杨强  刘耀儒 《岩土力学》2011,32(Z2):507-513

为解决盐岩储气库洞室形状以及库群布置的优化设计问题,将变形加固理论发展和完善为变形稳定理论,把塑性余能与强度折减系数的K-ΔE关系曲线作为储气库群的整体稳定性判据。在变形稳定理论的基础上,对不同形状和布置方式的洞室的整体稳定性进行定量评价,优化分析了洞室形状以及库群的布置方式,进而获得最具安全稳定性的洞室形状和布置方式。研究结果表明,变形稳定理论为盐岩储气库洞室形状和洞群布置方式的优化设计提供了一套实用有效的分析理论和方法。  相似文献   

Influential factors on the repose angle of desert sands     

JianBao Liu  NaiAng Wang  HongYi Cheng  WenTao Yang  ZhiQiang Guo 《寒旱区科学》2011,3(1):0017-0023

The repose angle is one of the most significant macroscopic parameters in describing the behavior of granular materials. Under a static condition, the repose angle is the steepest angle at which sediment particles can rest without motion. In this paper, we use existing data and aeolian physics to analyze the main factors that influence the repose angle of sand dunes, and we investigate different repose angles involving various states and types of materials. We have determined that different factors have differential influence on the magnitude of the repose angle. Our results show that for powdery (<400-μm diameter) desert sands, the main influential factor on the magnitude of repose angle is the molecular force among particles. Particle size does not influence the repose angle of desert sands directly, but has an indirect impact by affecting the grit sphericity and surface roughness, of which the grit sphericity acts as a major factor. Even at the same average particle size, the repose angle differs with different grain compositions. Furthermore, with increasing unevenness in grain composition, the repose angle increases correspondingly. Sand texture also has a direct influence on the repose angle of desert sands. In two sand samples having the same grain composition but different textures, the repose angles may be different. Water content has a stronger influence on the repose angle than any other factor. However, the relationship between the repose angle and water content is not a simple direct proportion. In fact, with increasing water content, the repose angle first increases and then decreases. These research results will be useful for understanding the mechanisms of dune transport, variations of dune morphology, and the stability and fluidity of dune sands.  相似文献   

The transfer matrix method applied to steel sheet pile walls     

D. A. Kort 《国际地质力学数值与分析法杂志》2003,27(6):453-472

This paper proposes two subgrade reaction models for the analysis of steel sheet pile walls based on the transfer matrix method. In the first model a plastic hinge is generated when the maximum moment in the retaining structure is exceeded. The second model deals with a beam with an asymmetrical cross‐section that can bend in two directions. In the first part of this paper the transfer matrix method is explained on the basis of a simple example. Further the development of two computer models is described: Plaswall and Skewwall. The second part of this paper deals with an application of both models. In the application of Plaswall the effect of four current earth pressure theories to the subgrade reaction method is compared to a finite element calculation. It is shown that the earth pressure theory is of major importance on the calculation result of a sheet pile wall both with and without a plastic hinge. In the application of Skewwall the effectiveness of structural measures to reduce oblique bending is investigated. The results are compared to a 3D finite element calculation. It is shown that with simple structural measures the loss of structural resistance due to oblique bending can be reduced. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

东秦岭陶湾岩群碳酸盐质糜棱岩的变质—变形特征及形成环境分析     

胡达  任升莲  宋传中  李加好  张妍  林寿发  李龙明  黄鹏  刘国厅 《地质论评》2015,61(5):1079-1088

东秦岭造山带北缘的陶湾岩群中分布着一套碳酸盐质糜棱岩,具明显的塑性变形,其展布和变质变形特征严格受洛南—栾川断裂带控制,是陶湾岩群碳酸盐岩在洛南—栾川断裂带晚加里东—早海西期构造活动过程中形成的。因此,对这套碳酸盐质糜棱岩的变质—变形特征及形成环境分析,可揭示洛南—栾川断裂带在这一时期构造活动的运动学、动力学及流变学特征。本文通过野外详细的观察和测量,结合室内显微构造分析和温压条件的计算,确定其变质相属低绿片岩相,变形机制是以方解石动态重结晶和细粒化作用为主的塑性变形。变形温度为350~420℃,差异应力为50~110 MPa。石英应变椭球体形态显示陶湾岩群遭受了强烈挤压变形。所以,陶湾岩群碳酸盐质糜棱岩是在强烈的斜向挤压碰撞环境下形成的,是秦岭微陆块向华北板块下斜向俯冲碰撞的结果 。  相似文献