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本文应用孔隙弹性理论,探讨了引潮力作用下饱和地质岩体的力学响应.首先通过引潮力作用下饱和岩体的自由能表达式,得到岩体孔压与应力、应力与应变之间的关系;然后从引潮力作用下饱和岩体的平衡微分方程出发,结合流-固耦合理论,分析了饱水岩体应变与引潮位之间的关系;最后推导出饱和岩体的两大力学物理量--孔压和潮汐应力(平均应力)与引潮位之间的物理关系.模型表明:饱和岩体孔压与引潮位成反比,平均潮汐应力与引潮位成正比;比例系数不仅与岩体骨架的Lame系数有关,而且与Biot模量有关.将模型应用于会理川-18井水位变化分析,估计出水位响应系数D,并以此为基础,求得岩体孔压、潮汐应力与引潮位的相关系数(A和C)及Skempton系数B.最后对比分析了耦合条件下与不考虑耦合时得到的各参数之间的差异,分析表明:对饱和地质岩体而言,应力、孔压对引潮力的响应是流-固耦合作用的产物;研究其力学响应时必须充分考虑耦合效应.模型的建立,为研究引潮力作用下井-承压含水层系统力学、水动力学、与地震有关的断层力学以及引潮力触发机制的定量研究提供了基础. 相似文献
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本文基于井水位微动态对固体潮和大气压响应的物理机制, 运用水-岩耦合理论, 建立了井水位对固体潮-气压综合作用的响应模型。 以邛崃川22井和南溪川12井为例, 通过井水位与固体潮和气压原始曲线的对比及拟合分析, 对井水位对固体潮-气压综合作用的响应模型进行了验证。 结果表明, 两口井对固体潮-气压综合响应非常好, 井水位的变化均由固体潮和气压变化引起。 两口观测井中, 以南溪川12井的水位综合响应能力较好, 邛崃川22井水位受到较多的杂讯干扰, 水位曲线日变化较复杂。 对邛崃川22井进一步分析表明, 利用井水位时段平均值可有效消除观测误差, 用小时值计算时可以忽略井水位对气压响应的滞后效应。 相似文献
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本文讨论了在构造应力水平达到岩石破裂临界值时引潮力、潮汐附加应力的动态变化与地震序列之间的关系，选用了中国大陆1970年以来7级以上地震序列资料，分析了引潮力水平分量动态变化与强震发震时间之间的关系，结果显示在一定时空范围内前震、主震及余震序列发震时刻的引潮力存在优势方向，多数地震发震时刻与选取时段引潮力水平分量的方位角相位比平均值仅为35%；对于构造复杂地区，结果显示引潮力水平分量的方位角不仅存在一个优势方向，还明显存在其他优势方向，可能与发震构造有关.根据1966～1976年中国九大地震震源机制解计算潮汐正应力和滑动方向的剪应力及其变化率，结果显示多数地震发震时刻潮汐剪应力接近最大值. 相似文献
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基于流体及岩石力学理论，利用气压和潮汐效应，研究了苏皖地区苏02井、苏03井、苏06井、苏18井和定远04井含水层介质在不排水状态下孔隙度和渗透系数的变化情况.结合井-含水层系统在受力和水均衡两种状态下的微动态变化模型，分析了各井水位自2014年下半年以来相继出现同步上升现象的水动力学成因机制.结果表明:① 5口井的气压系数与M2波潮汐因子之间存在明显的线性关系，即气压系数越大，潮汐因子也越大；②各井的孔隙度和渗透系数出现一组同步增大现象，主要与补给量大于泄流量、补给增强有关. 相似文献
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钻孔应变观测系统（岩石、 膨胀水泥和应变仪钢筒）存在显著的井孔耦合效应,只有确定这一耦合系数,才能得到地壳岩石的真实应变值,从而实现不同测点数据的可比性．本文根据双衬套理论及弹性力学理论,建立了三维空间应力作用下体应变与面应变观测力学模型,并进一步推导各自井孔耦合系数计算式,发现两组系数与井孔的受力状况密切相关,分别与不同力源引起的应变信号相对应．亦即应力比（钻孔轴向应力与平面应力之比）不同,耦合系数也不一样,体应变随应力比的增大而下降,面应变则上升. 本文结果还表明平面应力作用下的耦合系数与外加应力无关,只与观测系统本身有关,故数值保持恒定. 此外,文中对其影响因素也进行了分析,结果表明,体应变和面应变的井孔耦合系数均随岩石弹性模量和泊松系数的增大而增大,且前者的幅度较大,井孔耦合材料水泥对二者影响均很小． 相似文献
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The coupled mechanics of fluid-filled granular media controls the physics of many Earth systems, for example saturated soils, fault gouge, and landslide shear zones. It is well established that when the pore fluid pressure rises, the shear resistance of fluid-filled granular systems decreases, and, as a result, catastrophic events such as soil liquefaction, earthquakes, and accelerating landslides may be triggered. Alternatively, when the pore pressure drops, the shear resistance of these geosystems increases. Despite the great importance of the coupled mechanics of grain–fluid systems, the basic physics that controls this coupling is far from understood. Fundamental questions that must be addressed include: what are the processes that control pore fluid pressurization and depressurization in response to deformation of the granular skeleton? and how do variations of pore pressure affect the mechanical strength of the grains skeleton? To answer these questions, a formulation for the pore fluid pressure and flow has been developed from mass and momentum conservation, and is coupled with a granular dynamics algorithm that solves the grain dynamics, to form a fully coupled model. The pore fluid formulation reveals that the evolution of pore pressure obeys viscoelastic rheology in response to pore space variations. Under undrained conditions elastic-like behavior dominates and leads to a linear relationship between pore pressure and overall volumetric strain. Viscous-like behavior dominates under well-drained conditions and leads to a linear relationship between pore pressure and volumetric strain rate. Numerical simulations reveal the possibility of liquefaction under drained and initially over-compacted conditions, which were often believed to be resistant to liquefaction. Under such conditions liquefaction occurs during short compactive phases that punctuate the overall dilative trend. In addition, the previously recognized generation of elevated pore pressure under undrained compactive conditions is observed. Simulations also show that during liquefaction events stress chains are detached, the external load becomes completely supported by the pressurized pore fluid, and shear resistance vanishes. 相似文献
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— Rock-stress measurements performed in boreholes drilled from a tunnel at a depth of 800 m indicate that the minimum stress has been reduced from pre-excavation levels by drawdown in pore pressure. The disturbance to the ambient stresses extends well beyond two tunnel diameters. A model is developed to explain the inferred strong coupling between the pore pressure and minimum stress in the rock mass around the tunnel. The model includes the effects of poro-elasticity of the intact rock and the stiffness of the fractures. For the field situation under study where the fractures are unusually complaint, both poro-elasticity and fracture compliance could be important contributors to the coupling. Changes in pore pressure are shown to produce reductions in minimum stress that are at least 50% of the drop in pore pressure and probably higher. In more general situations, the poro-elastic component is likely to be the more significant of the two mechanisms and alone accounts for a coupling factor of 50%. In this context, the importance of fractures in crystalline conditions probably lies more in their promotion of penetrative drainage than their contribution to coupling coefficient. The results highlight the importance of establishing the extent and distribution of pore pressure drawdown about galleries from which stress measurements are to be conducted. 相似文献
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求取岩石基质体积模量的线形拟合方法(英文) 总被引：2，自引：2，他引：0
岩石基质的体积模量或其倒数--压缩系数,在进行油气预测的流体替换和孔隙度反演时,是重要的输入参数,但是利用现有方法很难准确求得。文中提出了一种求取该参数的线形拟合方法,该方法通过对Gassmann方程的合理简化并引入Eshelby-Walsh干燥岩石椭球包体近似公式,获得了计算岩石基质压缩系数的拟合公式,可方便地利用公式计算该参数。实际碳酸盐岩岩样的岩石物理测试分析显示:利用饱和岩样和干燥岩样测得的基质压缩系数的差异小于1%,说明所求参数是正确的,可靠的。 相似文献
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Introduction Analyzing tectonic stress field based on focal mechanism data is an important way to the study tectonic evolvement of lithosphere and associated dynamic process. Such studies growrapidly in China and abroad (Zoback, 1992; Plenefisch, Bonjer, 1997; XU, 1985; CUI, XIE, 1999). At present most of the studies focus on the inversion of focal mechanism data for the direction and relative magnitude of stress tensor, and few on absolute stress. Using focal mechanism and fault scratch,… 相似文献
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基于ABAQUS软件平台,应用自行开发的流固耦合动力模型孔压单元模拟场地土体,并通过黏弹性人工边界方法实现地震动的输入,对饱和土体场地中的双孔隧道结构在地震荷载作用下的动力反应进行研究。计算结果表明:在地震反应结束时刻,场地土体位移幅值在两隧道之间以及两隧道的附近区域较大,而远离隧道的区域则较小;场地底部区域土体的孔压幅值较大,而场地顶部区域土体则较小;隧道左右两侧拱腰部位的衬砌的应力较大,而拱顶部位则较小。计算结果同时表明了流固耦合动力模型孔压单元在饱和土体-隧道体系地震反应研究中的适用性。 相似文献
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The streaming potential across a porous medium is induced by a fluid flow due to an electric double layer between a solid and a fluid. When an acoustic wave propagates through a porous medium, the wave pressure generates a relative movement between the solid and the fluid. The moving charge in the fluid induces an electric field and seismoelectric conversion. In order to investigate the streaming potential and the seismoelectric conversion in the same rock sample, we conduct measurements with Berea sandstone saturated by NaCl solutions with different conductivities. We measure the electric voltage (streaming potential) across a cylindrical sample in NaCl solutions with different conductivities and under different pressures to determine the DC coupling coefficients. We also measure the seismoelectric signals induced by acoustic waves with a Berea sandstone plate at different frequencies and solution conductivities. The pressures of the acoustic waves are calibrated with a standard hydrophone (Brüel & 8103) at different frequencies (15–120 kHz). We calculate the quantitative coupling coefficients of the seismoelectric conversion at DC and at high frequencies with samples saturated by solutions with different conductivities. When the Berea sandstone sample is saturated by the NaCl solution with 0.32 mS/m in conductivity, for example, the DC and seismoelectric coupling coefficients at 15 kHz are 0.024 μV/Pa and 0.019 μV/Pa, respectively. The seismoelectric coupling coefficient is an important and helpful parameter for designing a seismoelectric tool. More experimental measurements of seismoelectric coupling coefficients in the frequency range of 100 Hz to 15 kHz are needed in the future. 相似文献
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A. Canitano P. Bernard A. T. Linde S. Sacks F. Boudin 《Pure and Applied Geophysics》2014,171(8):1759-1790
High-resolution borehole strainmeters are usually installed in tectonically active regions in order to detect slow-slip events, and to estimate slow transients related to earthquake swarms. However, they are also sensitive to other numerous influences, internal or external. Furthermore, the quality of their coupling to the rock through cementation, and the mechanical properties of the rock mass around them, have a critical influence on their records. Many of the existing strainmeters present such problems, and the correction for these effects often remains a challenge. In this paper, we present the analysis of the records of a high-resolution borehole dilatometer (Sacks–Evertson), located in the seismically active rift of Corinth (Greece) (station TRZ in the Trizonia island). We show that the instrument suffers from an only partial-solid coupling, and that the nearby sea tides have a direct (through elastic response) and indirect (through pore-pressure diffusion) effect on the dilatation signal, which adds up to the solid tidal strain source. We propose a methodology that allows, in a first step, to better separate the internal (solid tide) from the external (air pressure, sea level) influences, by calculating a frequency-dependent transfer function outside the range of the tidal periods. We then extrapolate this function, in particular at the tidal periods. In a second step, the resulting variation with frequency of the coupling coefficients with sea level led us to estimate the proportion of instrument not solidly cemented to rock (thus in contact with water pore pressure), which is about 90 % of the total height. Despite the small proportion of solid coupling, the sensor resolution remains very good up to a few tens of hours of a time period, thanks to the confining effects of the rocks on the local pore pressure. These results allow us to correct for the external effects, and reduce the associated variance by 80–90 % (in the period range of minutes to days). The empirical correction of the sea level effect could be explained using a simple Boussinesq’s approximation and 1D pore-pressure diffusion model, which contributed to better constraint of some of the poro-elastic parameters in the vicinity of the instrument. After correction, the solid tidal signal at the 24-h period is almost anti-correlated with those of the theoretical solid tide. This surprising result is consistent with a similar anti-correlation observed for the longest period surface waves (200 s) comparing the TRZ dilatometer signals to the strain measured by a nearby borehole strainmeter (MOK, 15 km). This could be related to the presence of a shallow fault close to the instrument, which would creep in response to seismic wave-related stress. 相似文献
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日月引潮力变化与某些地区地震发生时间的相关研究 总被引：11，自引：1，他引：11
本文研究了中国西南及华北地区日月引潮力和地震发生时刻的关系，通过对引潮力三分量的分析及把地震按处断裂构造分区，发现潮力的东西方向水平分量与地震发生时刻有密切关系。利用此结论可以提高对地震发生时刻的预报准确性。 相似文献
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根据双衬套钻孔应变观测力学模型,推导出平面应力作用下各分量应变观测中两个耦合系数(A、B)的计算公式,为进一步确定地壳应变场最大、最小主应变的数值及方向提供了必需的前提条件,对当前国内外开展的利用钻孔应变进行地震、火山和板块边界的观测研究具有一定积极意义.研究结果表明,A、B与用双环模型和复变函数法解算出的c(面应变响应因子)、d(剪应变响应因子)之间分别存在2倍的关系(c=2A,d=2B),并且二者绘制的曲线完全一致,c、d的物理含义分别是地壳岩石面应变与剪应变观测的井孔耦合系数. 相似文献
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计算井水位对固体潮和气压滞后响应的新方法 总被引：4，自引：0，他引：4
提出了一种计算井水位对固体潮和气压滞后响应的新方法.利用杜得森潮汐展开和泰勒级数展开,导出了计算井水位固体潮系数和气压系数以及滞后时间公式,并给出了考虑滞后影响的井水位固体潮和气压改正公式.利用该法处理了鲁03井水位和气压观测资料,求出该井水位固体潮系数为1.8mm/10~_(-3),水位对固体潮响应的滞后时间为1.53小时,气压系数为6.4mm/hPa,滞后时间为1.5小时。与以前的一般回归分析方法相比,改正后的水位中误差明显减小,改正效果较好。 相似文献
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潮汐应力与大震关系研究 总被引：2，自引：0，他引：2
选用1976—2009年全球震源深度小于70 km, MW≥7.0的地震为研究对象, 利用震源机制解资料, 对每个地震的发震断层面进行了判断, 得到233个地震的发震断层面解。 据此, 本文讨论了发震时断层面上的地球固体潮汐剪应力方向与滑动方向的关系以及潮汐正应力在发震时所处的相位, 发震时断层面的库仑应力值。 结果表明, 当潮汐剪应力方向与滑动方向一致时触发作用最为明显, 逆断层地震与潮汐的关系最为密切; 而当潮汐剪应力方向与滑动方向相反时, 地震较少发生。 相似文献