基于走时约束的分频分步零偏VSP波动方程多参数反演          下载免费PDF全文

韩璇颖  印兴耀  曹丹平 《地球物理学报》2020,63(2):666-686

在地震勘探中,描述复杂介质的正演和反演问题通常包含许多反映介质不同特性的参数.同时获得这些参数对进行更准确的岩性描述和油藏预测具有重要的理论和现实意义.为了提高频率域黏弹性波动方程的零偏VSP多参数反演的精度,本文对多参数反演的可行性进行分析,明确了目标函数的敏感程度及参数之间的耦合情况,提出了一种基于走时约束的分频分步多参数反演策略.首先利用零偏VSP资料构建先验信息,然后分别利用高、低频数据进行两步反演,也就是"三个参数反演+五个参数反演"的过程,以提高反演的稳健性和精度.利用此方法可同时得到零偏VSP数据可靠的弹性波速度、密度和品质因子,为精确的时-深关系及含油气的解释和预测奠定基础,同时也可以为地面地震叠前反演提供可靠有效的约束,增强地面地震反演精度.  相似文献   

Longitudinal vibration of a pile embedded in layered soil considering the transverse inertia effect of pile     

《Computers and Geotechnics》2014

The dynamic response of a viscoelastic bearing pile embedded in multilayered soil is theoretically investigated considering the transverse inertia effect of the pile. The soil layers surrounding the pile are modeled as a set of viscoelastic continuous media in three-dimensional axisymmetric space, and a simplified model, i.e., the distributed Voigt model, is proposed to simulate the dynamic interactions of the adjacent soil layers. Meanwhile, the pile is assumed to be a Rayleigh–Love rod with material damping and can be divided into several pile segments allowing for soil layers and pile defects. Both the vertical and radial displacement continuity conditions at the soil–pile interface are taken into account. The potential function decomposition method and the variable separation method are introduced to solve the governing equations of soil vibration in which the vertical and radial displacement components are coupled. On this basis, the impedance function at the top of the pile segment is derived by invoking the force and displacement continuity conditions at the soil–pile interface as well as the bottom of pile segment. The impedance function at the pile head is then obtained by means of the impedance function transfer method. By means of the inverse Fourier transform and convolution theorem, the velocity response in the time domain can also be obtained. The reasonableness of the assumptions of the soil-layer interactions have been verified by comparing the present solutions with two published solutions and a set of well-documented measured pile test data. A parametric analysis is then conducted using the present solutions to investigate the influence of the transverse inertia effect on the dynamic response of an intact pile and a defective pile for different design parameters of the soil–pile system.  相似文献   

High-temperature viscoelasticity of fine-grained polycrystalline olivine     

B. H. Tan  I. Jackson  J. D. Fitz Gerald 《Physics and Chemistry of Minerals》2001,28(9):641-664

 Torsional forced-oscillation and microcreep methods have been employed in a study of the viscoelastic behaviour of fine-grained polycrystalline olivine at high temperatures (to 1300 °C), seismic frequencies and low strain amplitudes. The Fo₉₀ specimens are of low porosity and low dislocation density. They vary in mean grain size from 8 to 150 μm and contain only trace amounts (≪0.1 vol%) of quenched melt glass. For T ≤ 900 °C, their behaviour is essentially elastic and the shear modulus G closely approaches that expected for a dense polycrystal from single-crystal elasticity data – confirming the suppression of thermal microcracking in␣this study. At higher temperatures, pronounced absorption-band dissipation and associated dispersion␣of the shear modulus provide evidence of linear viscoelastic behaviour. Both recoverable (anelastic) and permanent (viscous) strains are involved and the proportion of the latter increases with increasing temperature and decreasing frequency. Comparison of the results for the three specimens provides a clear indication that the viscoelastic behaviour, attributed to diffusional processes, is grain-size-sensitive with the dissipation and associated dispersion increasing with decreasing grain size. Both elastically accommodated and diffusionally accommodated grain-boundary sliding appear to be implicated. Received: 29 September 2000 / Accepted: 7 May 2001  相似文献   

软岩流变过程与强度研究   总被引：10，自引：0，他引：10  

郭志 《工程地质学报》1996,4(1):75-79

文中通过分析软岩流变特征找出流变速度与作用载荷之间的关系。利用U-相关曲线确定能够反映流变过程的4个特征点(流变起始点、等速流变起始点、加速流变起始点、流变破坏点).根据4个特征点的变化规律确定临界等速流变应力的方法和流变强度取值原则。  相似文献   

Visualization of time-dependent dynamics of postglacial rebound     

Ladislav Hanyk  David A. Yuen  Ctirad Matyska  Jakub Velímsky 《Visual Geosciences》2008,13(1):37-47

Postglacial rebound is a major geological process which plays an important role in many areas in the earth sciences. Up to now, most of the images derived from studies of the glacial isostatic adjustment phenomenon have been concerned with surface signatures, such as the uplift and gravity anomalies and not much attention has been paid on the dynamical responses in the mantle. We will make use of the 3D visualization package Amira to depict both the external and internal deformation histories of the transient viscoelastic flow inside the mantle induced by postglacial uplift. Of particularly great interest are the transient displacement fields and shear heating inside the mantle. This same visualization technology can be brought to bear in the future for visualizing tsunami waves in ocean basins excited by earthquakes, volcanic eruptions and InSAR images. We have also integrated the visualization results into the Google Earth virtual globe by combining this scheme with the Amira package to provide a better geographical and dynamical context. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Passive control of offshore jacket platforms   总被引：3，自引：0，他引：3  

K.C. Patil  R.S. Jangid   《Ocean Engineering》2005,32(16):1630-1949

The wave-induced dynamic force is one of the most important excitations to be dealt with in the design of offshore structures. In order to perform a reliable design of an offshore structure, it is important to obtain an exact evaluation of its dynamic response but also to examine the ways of reducing the response. This paper presents the response of offshore jacket platforms installed with energy dissipation devices such as viscoelastic, viscous and friction dampers under wave loading. The offshore jacket platforms are modeled as multi-degrees-of-freedom system provided with dampers at each floor location. The wave forces are modeled as per Morison's equation. The governing equations of motion of the jacket platform with dampers are derived and their solution in the frequency domain is presented. The uni-directional random wave loading is expressed by the Pierson-Muskowitz spectrum. The response of the jacket platform with viscoelastic, viscous and friction dampers is compared with the corresponding response without dampers in order to investigate the effectiveness of the passive control systems. It is observed that the additional dampers add substantial damping to structure and thus favorably control the response of platform structure. Among the various energy dissipation devices used for study, the viscoelastic dampers perform better in comparison to the other dampers. This is due to the fact that the added viscoelastic dampers contribute to increased viscous damping as well as lateral stiffness which reduces the response of the offshore jacket platforms significantly.  相似文献   

P-wave velocity and gradient images beneath the Okinawa Trough   总被引：1，自引：0，他引：1  

Zhi Wang  Runqiu Huang  Jinli Huang  Zhenhua He   《Tectonophysics》2008,455(1-4):1-13

To investigate the influence of spatial change of viscosity on postseismic deformation associated with the interplate 1946 Nankai earthquake (M 8.0) at the Nankai Trough, southwest Japan, we newly constructed a realistic viscoelastic structure model, taking into account temperature- and depth-dependent viscosity of materials. For this purpose, we first compiled leveling and triangulation data during postseismic periods and clarified characteristics of the amount and spatial patterns of postseismic vertical displacement and principal strain fields. Then, we calculated the spatial distributions of viscosity from temperature and flow fields, which were obtained from 2D subduction models. By incorporating the obtained viscosity structure into 3D viscoelastic finite element models, we constructed a temperature- and depth-dependent viscosity structure model (MODEL P2). Based on MODEL P2, we constructed a viscoelastic structure model, taking into account Poisson's ratio for the oceanic plate and low-velocity regions and the existence of low-viscosity materials beneath the Shikoku and Chugoku districts (MODEL P3), which were revealed from seismic tomography. We also constructed a conventional layered viscoelastic structure model (MODEL L1) and plate subduction model (MODEL P1) with constant viscosity for each region and evaluated the effects of different viscoelastic structures on postseismic surface deformations, using the coseismic slip distribution obtained by inversion analyses of geodetic data. We also compared the calculated surface deformations with the observed postseismic crustal deformations in and around Shikoku. The results show that postseismic surface deformation fields for the newly constructed MODEL P2 are rather different from those for MODELs L1 and P1. Landward horizontal displacements for MODEL P2 are smaller than those for MODELs L1 and P1, seaward horizontal displacements are negligible, and vertical displacement is characterized by small subsidence over Shikoku. The postseismic horizontal principal strain field for MODEL P2 is characterized by contractions in the N–S to NW–SE directions at amounts smaller than those for MODELs L1 and P1. Postseismic surface deformations for MODEL P3 are almost the same as those for MODEL P2. The observed postseismic vertical displacement and horizontal principal strain fields could not be explained by the viscoelastic response for the realistic viscoelastic structure models P2 and P3. This indicates that the effects of elastic and viscoelastic responses due to interplate coupling on the plate interface, after-slip at the extension of the coseismic slipped region, and poroelasticity should be taken into account to precisely estimate postseismic surface deformation. This also suggests that, in order to evaluate postseismic crustal deformations derived from a large interplate subduction zone earthquake, it is essential to use realistic temperature- and depth-dependent viscoelastic structure models.  相似文献   

任意震源力作用下多层粘弹性半无限地基平面问题的解析解   总被引：2，自引：0，他引：2  

孟凡顺  王优先 《地震工程与工程振动》1995,15(3):32-37

本文利用Ｆｏｕｒｉｅｒ变换及矩阵传递技术，导出了在任意震源力作用下多层粘弹性半无限地基平面问题的一般解析表达式。本文的方法概念清晰、公式简便实用。文中给出了计算实例，所得结果与现有文献的数值计算结果一致。  相似文献   

粘弹性岩体力学模型识别与参数反演解析方法研究   总被引：8，自引：0，他引：8  

薛琳 《工程地质学报》1995,3(1):70-77

本文基于圆形和非圆形隧道围岩粘弹性位移反演分析解析方法的最新进展，根据隧道围岩力学参数解析解的反演规律，提出了五个粘弹性力学模型识别与参数定理，并通过算例和工程实例对所给出的定理作了必要的验证。  相似文献   

Rheological and physical characteristics of crustal-scaled materials for centrifuge analogue modelling     

《Journal of Structural Geology》2016

We characterize a set of analogue materials used for centrifuge analogue modelling simulating deformation at different levels in the crust simultaneously. Specifically, we improve the rheological characterization in the linear viscoelastic region of materials for the lower and middle crust, and cohesive synthetic sands without petroleum-binding agents for the upper crust. Viscoelastic materials used in centrifuge analogue modelling demonstrate complex dynamic behaviour, so viscosity alone is insufficient to determine if a material will be an effective analogue. Two series of experiments were conducted using an oscillating bi-conical plate rheometer to measure the storage and loss moduli and complex viscosities of several modelling clays and silicone putties. Tested materials exhibited viscoelastic and shear-thinning behaviour. The silicone putties and some modelling clays demonstrated viscous-dominant behaviour and reached Newtonian plateaus at strain rates < 0.5 × 10⁻² s⁻¹, while other modelling clays demonstrated elastic-dominant power-law relationships. Based on these results, the elastic-dominant modelling clay is recommended as an analogue for basement cratons. Inherently cohesive synthetic sands produce fine-detailed fault and fracture patterns, and developed thrust, strike-slip, and extensional faults in simple centrifuge test models. These synthetic sands are recommended as analogues for the brittle upper crust. These new results increase the accuracy of scaling analogue models to prototype. Additionally, with the characterization of three new materials, we propose a complete lithospheric profile of analogue materials for centrifuge modelling, allowing future studies to replicate a broader range of crustal deformation behaviours.  相似文献