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Transient creep and semibrittle behavior of crystalline rocks 总被引：1，自引：0，他引：1
We review transient creep and semibrittle behavior of crystalline solids. The results are expected to be pertinent to crystalline rocks undergoing deformation in the depth range 5 to 20 km, corresponding to depths of focus of many major earthquakes. Transient creep data for crystalline rocks at elevated temperatures are analyzed but are poorly understood because of lack of information on the deformation processes which, at low to moderate pressure, are likely to be semibrittle in nature. Activation energies for transient creep at high effective confining pressure are much higher than those found for atmospheric pressure tests in which thermally-activated microfracturing probably dominates the creep rate. Empirical transient creep equations are extrapolated at 200° to 600°C, stresses from 0.1 to 1.0 kbar, to times ranging from 3.17×102 to 3.17×108 years. At the higher temperatures, appreciable transient creep strains may take place but the physical significance of the results is in question because the flow mechanisms have not been determined. The purpose of this paper is to stimulate careful research on this important topic. 相似文献
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首先介绍了在不同压力组合下关于油母页岩的蠕变实验.实验表明,在瞬时扩容后,蠕变过程中的依赖时间的扩容持续增长.在引入反映岩石扩容程度时的损伤变量后,建立了损伤演化方程和本构方程以描述蠕变扩容的变化规律.最后,数值模拟了体应变与时间关系,与实验结果基本一致. 相似文献
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冻土蠕变过程中结构的CT分析 总被引：5，自引：1，他引：5
ＣＴ为非破坏的持续检测和定量描述不同实验条件下试样的内部结构提供了可能，本文利用这一手段观测分析了冻土蠕变过程结构的变化情况，认为冻土蠕变过程中所进行的发育微裂隙、颗粒集合体的破坏以及其它结构缺陷的增生与扩展，制约着土结构的强化与弱化作用，控制着蠕变过程的形态特征，同时还给出了ＣＴ值与物密度和含水量之间的定量关系。 相似文献
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利用滑动速率、古地震资料估算走滑断裂的粘滑及蠕滑量的方法 总被引：1，自引：0，他引：1
断层走滑包括粘滑和蠕滑,前者是伴有强震发生的快速运动,后者则是一种缓慢的无震稳滑运动。这２ 种运动常随时间交替出现,共同构成了断层的基本运动方式。在利用断层滑动速率讨论大震重复率的问题中,人们最关心的问题则是如何从总滑动量中分辨和划分出其中所包含的粘滑和蠕滑量,特别是对蠕滑量的划分,因为它直接影响着大震重复率的正确性。笔者在野外考察的基础上,对昌马活动断裂的位移量进行了分级,确定出昌马断裂带全新世以来的水平滑动量大致可划分为５个级别：３１～４１ ｍ ;２５～３１ ｍ ; １５～２２ ｍ ; ８～１３ ｍ ;１～５．５ ｍ ,同时依据古地震学方法并结合１４Ｃ断代法及断层崖形成年代的数学模拟计算,求得全新世以来在昌马断裂带上共发生５ 次古地震事件。在上述２ 项资料确定的基础上,进一步对昌马断裂带的粘滑及蠕滑量进行了划分,并给出了它们随时间的变化情况 相似文献
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Creep,stable sliding,and premonitory slip 总被引：3，自引：0，他引：3
John M. Logan 《Pure and Applied Geophysics》1978,116(4-5):773-789
Summary The current status of laboratory investigations into creep, stable sliding and premonitory slip is reviewed and some new material is presented. It is postulated that pre-cut rocks and those with simulated gouge layers undergo a transition with increasing confining pressure from (1) stable sliding to stick-slip, to (2) sliding along the pre-cut with deformation of the country rock, to (3) homogeneous flow of the specimen without slip along the pre-cut. Stick-slip behavior is not always present. Decreasing displacement rates are found to enhance stick-slip. Mixtures of gouge are found to be significant in controlling the behavior of sliding with 10–20 percent of anhydrite mixed with quartz or clays mixed with anhydrite shifting the sliding mode from stable stick-slip or stick-slip to stable sliding, respectively. Premonitory slip may be one of the most significant short term precursors of earthquakes. Although widely recognized in the laboratory, little systematic work has been completed. Variations in pore pressure, resistivity and seismic velocities have been investigated. Clearly much work needs to be done into these topics before a clear understanding is achieved. 相似文献
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J. Moeyersons 《地球表面变化过程与地形》1978,3(2):115-128
This study reveals that the Quaternary mantle of reworked Kalahari Sands undergoes a post-sedimentary composite process at the archaeological site of Gombe (Kinshasa, Zaïre). There is a biological activity which consists of an upworking of soil particles, mainly by termites and worms. This causes a diminishing dry volume weight of the sediment. In response, the mantle reconsolidates. When the soil surface is horizontal, the particles which are not brought up will sink down in the soil profile as a result of the reconsolidation. When the soil surface is inclined, it is only the resettlement of the sediment which can give rise to creep, caused by wetting and drying. Creep of the dead mineralogical material alone seems to be very improbable once the structure and settlement of the sediment are in equilibrium with a given slope. Only a new phase of bioturbation can induce further creep movements. The experiments have shown that stone implements in reconsolidating Kalahari Sands do not exactly accompany the compaction movement of the sediment. Depending on their form, their size, their orientation and the water content of the sediment around them, stone implements can undergo differential movements during the reconsolidation process. This can result in a dispersion of the implements over levels of different ages. As creep is a phenomenon, going hand in hand with the resettlement of the sediment after biogenic upworking, partially analogous movements of stone implements can be expected in a creeping Kalahari Sands mantle. Partial or total reconcentration of the stone implements at the base of affective biogenic activity can be expected. This can lead to typical stone-line profiles which must be interpreted very carefully. 相似文献
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在高应力状态下坝料的流变较为明显。为研究坝料流变对混凝土面板坝应力变形的影响,采用长科院九参数幂级数流变模型及其试验参数,对某高混凝土面板堆石坝进行应力、变形分析。结果表明,坝料流变使坝体变形明显增加,坝体应力有所减小。考虑坝料的流变特性后的面板法向位移(挠度)明显增加,面板坝轴向和顺坡向应力极值增加。对于分期浇筑面板和分期蓄水的高混凝土面板堆石坝,选用合适的流变本构模型正确地模拟堆石体的流变特性,可以为大坝填筑进度及面板分期浇筑时间的确定提供参考,并有助于正确地预测大坝的应力变形。 相似文献
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Radiocarbon dates obtained on organic materials overridden by a gelifluction lobe allow some estimate of past gelifluction rates for a site near sea level in northern Labrador. The calculated mean gelifluction rate for the last 400 years is in the order of 8 mm yr?1, somewhat higher than the average gelifluction rate described from other locations in the Canadian Arctic. The lobe contains two lithostratigraphic units: an inner diamicton, probably representing a buried gelifluction lobe, overlain by a silt/clay unit which may have been emplaced abruptly as a solifluction sheet. Mean creep rates for these units were in the order of 5 mm yr?1 and 15 mm yr?1 respectively. The area is presently subsiding, and transgressive beach material overlies terrestrial organics which are approximately 300 years old. 相似文献
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为量化冰及冰川在流变过程中位错密度随流变应力的变化,发展了一个基于位错的非线性弛豫模型.模型的计算表明：在冰的指数蠕变阶段,滞弹性试验所形成的应力/应变滞后环的宽度与面积随流变应力的增加呈线性增加,位错密度随流变应力的增加呈平方增加;在冰的线性蠕变阶段,滞弹性试验所形成的应力/应变滞后环的宽度、面积和位错密度保持不变. 相似文献
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Robert J. Twiss 《Earth and Planetary Science Letters》1976,33(1):86-100
The rheology of dry polycrystalline olivine is examined by adopting a hyperbolic sine flow law (which reduces to a power law below 3 kbars) for high stress behavior, and a model for diffusion accommodated, coherent, grain boundary sliding (structural superplastic creep) for low stress behavior. The model for superplastic creep gives a linear relation between stress and strain rate and is consistent with the behavior of polycrystalline olivine during ductile faulting experiments (Post, 1973). For any given stable grain size, linear superplastic creep is promoted by relatively low stress and temperature. For a 1 -cm grain size and a homologous temperature between 0.6 and 0.8, superplastic creep dominates below transition stresses between 402 and 25 bars, respectively. Transition stresses are higher for smaller grain size and lower temperature. If grain size is stress dependent, superplastic creep is non-linear and dominates above a stress of 300 bars. Below that stress, relatively lower temperatures promote superplastic creep. Grain size may be stabilized by either physical or kinetic inhibition of grain growth, thereby allowing linear superplastic creep in the mantle. Results suggest that superplastic creep can dominate in most of the upper mantle except possibly for the asthenosphere where homologous temperatures are maximal and hyperbolic sine law creep can dominate. Mantle diapirism is at least in part accomplished by superplastic flow above and along the margins of the rising diapir. 相似文献
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利用鲜水河断裂带1990年1月-2009年12月的蠕变与短基线数据,采用小波变换与断层运动学分析方法,获取构造活动产生的断层形变速率.结合近场断层形变测量与GPS资料,分析了该断裂带的分段活动特征及时空演化.结果显示:(1)不同段落断层活动方式存在差异性.鲜水河断裂带分段活动现象显著,以道孚县为界,以北的炉霍、道孚断层走滑量相对较大且活动方式稳定,显示张性和左行走滑;以南的乾宁、折多塘断层活动微弱,走滑量小,且滑动状态复杂,其中,乾宁断层为压性和左行走滑,折多塘断层为微弱的右行走滑.这种分段活动特征可能与断层几何及巴颜喀拉块体内部次级块体的差异运动有关.(2)不同时期断层走滑方式存在交替性.鲜水河断裂带虽以左行走滑为主,但在汶川地震前一些断层段出现过逆向走滑现象.汶川地震前2年,炉霍、道孚断层左行走滑减弱,乾宁、折多塘断层在2007年出现过逆向走滑,至2009年底,逆向走滑区域保持扩展态势.(3)不同测点间距得到的断层错动速率和变形带空间分布特征不同.不同测量方法的分析结果表明,鲜水河断裂带不同段落和跨距宽度的走滑速率有所不同:测点间距18.7~65.1 m的蠕滑速率为0.01~0.78 mm/a;测点间距72~288 m的短基线测量为0.02~2.46 mm/a,点距十几至几十公里的GPS观测为6~11 mm/a;地质滑动速率5~15 mm/a.随测点间距的增加,平行断层的位移速率按对数函数增长,视剪应变率按幂函数衰减.我们推测,大间距测点的数据中既包含了跨断层的错动,也包含了断层两侧块体的分布变形;现今的断层形变测量与地质调查之间的差异,说明断层错动速率在时间上不是常数. 相似文献
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用开尔文黏弹模型对实验蠕变曲线和冰后期地面抬升观测曲线进行反演,得到相关的黏弹参数,发现所有的黏弹参数都随实验（或观测）时间长度发生有规律的变化, 表明黏弹参数是实验(或观测)时间的函数.在此基础上提出非定常参数的黏弹模型,将通常采用的剪切模量μ2、弛豫时间τ 和黏度η 相应地从常数修正为时间的函数μ2(t)、τ(t) 和η（t）,检验表明修正后的开尔文模型可以更好地符合实测蠕变曲线.用修正后的μ2(t)对软流层的黏度进行估算,其值约为4.6×1020 Pa·s. 相似文献
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本文对青藏高原东北缘一些主要断裂（包括阿尔金、昌马、毛毛山等断裂）的断层泥首次进行了研究。在对断裂带的内部结构、围岩成分、断层泥的厚度及石英颗粒表面特征等综合分析的基础上对断裂的活动年代、活动方式及断层泥形成的深度进行了讨论。石英颗粒表面上溶蚀程度（颗粒表面的光滑程度、凹凸现象及孔洞发育情况）可划分为６种类型并且每种类型都有相应的年代。根据断裂的粘滑、蠕滑特征，对该区的各活动断裂进行了粘滑段与蠕滑段的划分。用红外光谱与稀土元素的分析结果，算得断层泥形成的深度在地壳１０ｋｍ范围内。 相似文献
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中等地震活动增强作为强震标志的研究 总被引：7，自引：0，他引：7
通过对(1990~1996年)发生在我国大陆及边境地区24次6级以上地震的分析研究表明,80%的强震主震前在震源区及附近有中等地震活动增强的过程。异常表现出共同的基本特征,即长期平静→增强活动→震前平静→发震。震前平静至发震大约经历几个月到2年时间(平均10个月左右),可以作为中短期地震预报判据。用岩石蠕变声发射实验来解释这一现象,可把中等地震活动增强看作是稳态蠕变阶段后期发生的广义前震。 相似文献
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利用人工合成的多晶材料研究了镍锗尖晶石在位错域的高温蠕变性质.多晶材料的颗粒尺寸约8μm.单轴压缩试件为圆柱状,使用气体介质围压筒.常压蠕变试验过程中,围压为300MPa,温度为1373-1523K,应力在55-330MPa范围内.从实验结果得出了镍锗尖晶石在位错域的流动律,应力指数n=29±01,表明流动的微观机制为位错蠕变.与其他尖晶石进行对比可以发现一个力学同构群,虽然在正尖晶石和反尖晶石之间存在一定的差异.在位错蠕变域,尖晶石与橄榄石归一化的强度类似.由于尖晶石的剪切模量比橄榄石高50%,其实际强度也比橄榄石高.将橄榄石和尖晶石的蠕变数据外推到地球内部条件时,由于其高应力指数,橄榄石则有可能比尖晶石的强度高. 相似文献
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B.K. Atkinson 《Earth and Planetary Science Letters》1976,29(1):210-218
A deformation mechanism map, depicting the fields of stress and temperature in which modes of plastic flow are dominant (i.e. provide the fastest strain rate) has been calculated for polycrystalline, stoichiometric galena for each of two grain sizes; namely, 10 and 103 μm. The deformation mechanisms considered were dislocation glide, dislocation creep (i.e. creep involving dislocation climb), Nabarro-Herring creep and Coble creep.During folding and related tectonic deformation in the earth's crust steady-state flow of galena may occur by either dislocation or diffusion creep at very low differential stresses (typically ranging from 100 bars down to 10?2 bar, or less). The dislocation creep field will be enlarged at the expense of that for diffusion creep, however, if (a) the stress dependence of strain rate for dislocation creep decreases at low stresses and if the grain size is greater than 10 μm, or (b) diffusion creep rates decline at high strains due to the presence of second-phase particles in the grain boundaries. It is probable that dislocation glide will be the dominant deformation mechanism in galena only at low temperatures and fast strain rates and it is unlikely to be the dominant mechanism during folding. Kinking may have some potential as an indicator of these temperatures and strain rates. 相似文献