岩石受力状态对弹性波传播速度影响的初步研究

岩石所受的三向应力状态对其弹性波传播性质有一定的影响，此认识为所做的以泥质砂岩、泥岩和硅质胶结的坚硬砂岩为试样的实验所证实。为保证岩石中存在微隙，对部分试样还作了高温预热处理。实验结果表明，泥质砂岩和泥岩的Ｖ＿ｐ／Ｖ＿ｓ值几乎保持不变，但坚硬砂岩的Ｖ＿ｐ／Ｖ＿ｓ值曲线却在应力达破坏荷载的９０％左右时出现下凹现象，经热处理的硬砂岩的这一下凹现象则更突出。     

The effect of an interface boundary layer on the resonance properties of a buried structure

This paper presents a model for the analysis of the diffraction of plane waves at a cavity in an infinite homogeneous linear elastic medium supported by a segmented lining. An elastic boundary layer is introduced between the cavity lining and the infinite medium. The boundary layer is simulated by ‘elastic boundary conditions’ in which the stress is proportional to the relative displacement of the lining and of the surrounding medium boundary. A closed‐form analytical solution of the problem was obtained using the Fourier–Bessel series, the convergence of which was proven. It was shown that the number of series terms required to obtain a desired level of accuracy can be determined in advance. Using amplitude–frequency response analysis it was shown that the boundary layer produces additional ‘pseudo‐resonance’ frequencies that depend on the layer properties. These frequencies are almost identical to the eigenvalues obtained from the simple analysis of a segmented elastically supported lining. Copyright © 2003 John Wiley & Sons, Ltd.     

Dynamic Analysis of a Single-Column Platform (II)

This paper describes the study of a single-column structure used as well-head platform. In order to check the reliability of computation theory and programme, model tests have been carried out. The paper introduces the conclusion of tests and the dynamic properties of single-column platform are obtained.     

MathCAD在地质模拟的数据分析和处理中的应用

地质模拟正从一维、二维技术向三维技术发展,需要分析和处理的数据成倍甚至上百倍增长.随着计算机技术的快速发展,数据分析和处理的速度也随之快速增长,但运用常规的编程来分析和处理这些数据费时又费力.而MathCAD具有解决这一问题的强大的数据分析、处理功能和仿真功能,将MathCAD应用于地质模拟的数据分析和处理中是十分必要的和可行的.本文简要介绍了MathCAD的功能和其在各类地质模拟的数据分析和处理中的应用.     

应用农田水量平衡模型估算土壤水渗漏量

建立了一个农田水量平衡模型。并据于模型假设的条件,模拟计算了在冬小麦-夏玉米及冬小麦-裸地条件下历年1m土层土壤水渗漏量。结果表明,土壤水渗漏量与季节内降水量呈正相关,但在不同作物种植制度下有不同的相关关系式。不同水文频率年型下的渗漏量具有明显的差异,湿润年型下比干旱年型下的渗漏量多70～140mm,冬小麦-裸地比冬小麦～夏玉米种植条件下的渗漏量多30～50mm。     

兴文石海世界地质公园SWOT分析和产品营销战略

兴文世界地质公园拥有全国及世界重要意义的"地球特大漏斗"、"中国最大的石海"和"中国最长的游览洞穴"等景观。采用SWOT分析法,对兴文石海世界地质公园的内部优势、劣势和外部机遇、挑战进行分析,提出了适宜的旅游产品营销战略,以改进其旅游产品和客源市场的开发。     

Settlement prediction by spatial-temporal random process using Asaoka's method

A methodology was presented for observation-based settlement prediction with consideration of the spatial correlation structure of soil. The spatial correlation is introduced among the settlement model parameters and the settlements at various points are spatially correlated through these geotechnical parameters, which naturally describe the phenomenon. The method is based on Bayesian estimation by considering both prior information, including spatial correlation and observed settlement, to search for the best estimates of the parameters at any arbitrary points on the ground. Within the Bayesian framework, the optimised selection of auto-correlation distance by Akaike's Bayesian Information Criterion (ABIC) is also proposed. The application of the proposed approach in consolidation settlement prediction using Asaoka's method is presented in this paper. Several case studies were carried out using simulated settlement data to investigate the performance the proposed approach. It is concluded that the accuracy of the settlement prediction can be improved by taking into account the spatial correlation structure and the proposed approach gives the rational prediction of the settlement at any location at any time with quantified uncertainty.     

上海黏性土剪切带形成的数值模拟分析

各种工程事故表明：现有的土力学计算模型均未考虑应变局部化问题,故不能解释这些工程事故的发生,因此应变局部化和剪切带形成的研究成为国际土力学界研究热点之一。数值模拟是研究剪切带形成的一个重要内容。在数值模拟中首先进行剪切带形成条件的研究,接着考虑土质不均匀性的影响,引入弱单元和强单元,进行弱单元与强单元影响力的研究。     

Innovative substructuring technique for hybrid simulation of multistory buildings through collapse

Hybrid simulation combines numerical and experimental methods for cost‐effective, large‐scale testing of structures under simulated dynamic earthquake loads. Particularly for experimental seismic collapse simulation of structures, hybrid testing can be an attractive alternative to earthquake simulators due to the limited capacity of most facilities and the difficulties and risks associated with a collapsing structure on a shaking table. The benefits of hybrid simulation through collapse can be further enhanced through accurate and practical substructuring techniques that do not require testing the entire structure. An innovative substructuring technique for hybrid simulation of structures subjected to large deformations is proposed to simplify the boundary conditions by overlapping the domains between the numerical and experimental subassemblies. The advantages of this substructuring technique are the following: it requires only critical components of the structure to be tested experimentally; it reduces the number of actuators at the interface of the experimental subassemblies; and it can be implemented using typically available equipment in laboratories. Compared with previous overlapping methods that have been applied in hybrid simulation, this approach requires additional sensing in the hybrid simulation feedback loop to obtain internal member forces, but provides significantly better accuracy in the highly nonlinear range. The proposed substructuring technique is verified numerically and validated experimentally, using the response of a four‐story moment‐resisting frame that was previously tested to collapse on an earthquake simulator. Copyright © 2014 John Wiley & Sons, Ltd.     

Directional dependence of P- and S-wave propagation and polarization in foliated rocks from the Kola superdeep well: Evidence from laboratory measurements and calculations based on TOF neutron diffraction

We have measured P- and S-wave velocities on two amphibolite and two gneiss samples from the Kola superdeep borehole as a function of pressure (up to 600 MPa) and temperature (up to 600 °C). The velocity measurements include compressional (Vp) and shear wave velocities (Vs1, Vs2) propagating in three orthogonal directions which were in general not parallel to inherent rock symmetry axes or planes. The measurements are accompanied by 3D-velocities calculations based on lattice preferred orientation (LPO) obtained by TOF (Time Of Flight) neutron diffraction analysis which allows the investigation of bulk volumes up to several cubic centimetres due to the high penetration depth of neutrons. The LPO-based numerical velocity calculations give important information on the different contribution of the various rock-forming minerals to bulk elastic anisotropy and on the relations of seismic anisotropy, shear wave splitting, and shear wave polarization to the structural reference frame (foliation and lineation). Comparison with measured velocities obtained for the three propagation directions that were not in accordance with the structural frame of the rocks (foliation and lineation) demonstrate that for shear waves propagating through anisotropic rocks the vibration directions are as important as the propagation directions. The study demonstrates that proper measurement of shear wave splitting by means of two orthogonal polarized sending and receiving shear wave transducers is only possible when their propagation and polarization directions are parallel and normal to foliation and lineation, respectively.