3-D rheologic model of earthquake preparation (II): Strain field and its applications

Introduction Based on the elastic theory of the hard inclusion (Dobrovolskii, 1991), we developed an inclusion theory of rheologic medium, and applied the results of bulk-strain field of a rheologic inclusion model to explain the spatial-temporal evolution process of earthquake precursors (SONG, et al, 2000). In the former paper (SONG, et al, 2003), we derived the viscoelastic displacement field of the rheologic inclusion model on the basis of the analytic expression of displacement field o…     

花岗岩研究进展 ———ISMA花岗岩类分类综述

本文在论述花岗岩主要分类的基础上论述了ISMA花岗岩类的基本含义,讨论了人们在以后应用和推广ISMA这类花岗岩分类方案时存在的一些问题,指出了ISMA花岗岩类本身在分类过程中存在的一些基本问题。     

地热井常见主要问题分析与研究

针对目前地热井施工技术现状及地热井使用中常见的问题，进行了较为详细的分析和研究，并就今后发展方向和建议进行了初步探讨。     

宝鸡市气候服务系统

本文首先给出了雨水集蓄利用的概念，针对黄土高原地区十分匮乏的水资源和严重的水土流失现状，提出了在该区实施雨水集蓄的可行性。在此基础上，对雨水集蓄利用在各个方面所取得的成就和存在的问题，进行了深入细致的分析，并对亟待解决的问题和今后的发展方向进行了展望。     

燕山造山带构造变形格局研究及相关问题

燕山造山带具有极其复杂的地质结构构造，其复杂性在现有公开出版的地质图件中未能有效地反映出来。从事地学研究的科研人员，以公开出版的地质图件为基础所衍生的相关分析图件和由此作出的结论与野外实际地质情况往往相去甚远。本文作者近年来所做基础地质调查成果显示，基础地质调查成果的缺陷成为制约国家地学科研发展的严重障碍。影响基础地质调查成果质量提高的原因很多，但较为重要的是国家对基础地学科研资金的政策性投入存在问题。     

Numerical and theoretical research on stress distribution in the loosening zone of the trapdoor problem

The traditional theory of soil arching effect was developed on the assumption that stress distribution in the loosening zone is uniform. However, because of the deflection of principal stress' direction, the stress distribution in the loosening zone is actually ununiform. For the evaluation of principal stress axis deflection and stress redistribution, a discrete element method numerical model of trapdoor problem is established for the simulation of soil arching effect. Based on the numerical results, an arc shape of major principal stress trajectory and uniform horizontal stress distribution at the same depth of the loosening zone are adopted. An analytical model is raised to estimate the average loosening earth pressure acting on the trapdoor and stress distribution in the loosening zone at a limit state. In addition, comparison studies are carried out between the predictions of the proposed solutions and discrete element method numerical results as well as available model test results, thereby validating the accuracy of the proposed theoretical model. Both numerical and theoretical results indicate that the vertical stress distribution in the loosening zone is obviously ununiform. The load acting in the middle of loosening zone is transferred toward two sides so that the vertical stress distribution in loosening zone is concave.     

基于部分最小二乘岭估计的粗差定值定位

在利用部分最小二乘原理进行粗差定值定位时,模型的法方程矩阵可能存在病态性,使得到的粗差定值定位结果不可靠。文中针对观测数据包含多个粗差且法方程病态问题,利用岭估计处理病态问题,建立部分最小二乘岭估计的粗差定值定位方法,给出粗差搜索步骤,利用迭代算法实现多个粗差的定值和定位。通过模拟算例分析部分最小二乘法、部分最小二乘岭估计在粗差搜索方面的效果,从另一个角度探讨粗差处理方法,推广现有的误差理论,证明文中方法的有效性。     

重力场数学拟合模型解的影响因素探究

为了提高地球重力场模型不适定方程求解的精度,该文采用谱分析方法从级数展开阶数、数据采样率及数据缺失量3个方面探索影响数学拟合效果的根本因素:从常用的三角级数及勒让德级数模型出发,引出重力场拟合模型球谐函数模型,观察在改变级数展开阶数、数据采样率及数据缺失量等情况下所对应设计矩阵谱结构的变化,并从微观上研究影响误差分配的有关因素及最小奇异值对误差的决定性作用,为探求重力场模型解不准的原因及实现更高精度的全球重力场模型的建立提供参考。     

SEQUENTIAL STIFFNESS DESIGN FOR SEISMIC DRIFT RANGES OF A SHEAR BUILDING–PILE–SOIL SYSTEM

A shear building supported by a prescribed pile–soil system is subjected to bedrock earthquake input. A new design procedure is presented for generating a sequence of stiffness designs satisfying the constraints on interstorey drifts. The mean peak interstorey drifts of the shear building subjected to a set of spectrum-compatible ground motions at the bedrock are evaluated by a modal combination rule. Tuning of the fundamental natural period of a shear building with a fixed base with that of a shear beam ground results in a non-monotonic sequence of stiffness designs with respect to a ground stiffness parameter and previous approaches cannot be applied to such a problem. This difficulty in finding such a non-monotonic sequence is overcome by utilizing the ground stiffness parameter and the superstructure stiffness parameter alternately in multiple design phases and by developing a new multi-phase perturbation technique. Fundamental characteristics of this sequence of stiffness designs and the effect of ground stiffnesses on the design of the shear building are disclosed. It is further shown that the stiffness contour method is also useful for the design procedure such that a scattering effect in the estimates of ground stiffnesses is taken into account. The usefulness of the proposed procedure of sequential stiffness design and contour line method is demonstrated through several sequential design examples.     

THE SETTLEMENT OF A RIGID CIRCULAR FOUNDATION RESTING ON A HALF-SPACE EXHIBITING A NEAR SURFACE ELASTIC NON-HOMOGENEITY

The present paper examines the elastostatic problem pertaining to the axisymmetric loading of a rigid circular foundation resting on the surface of a non-homogeneous elastic half-space. The non-homogeneity corresponds to a depth variation in the linear elastic shear modulus according to the exponential form G(z)=G₁+G₂e^-ζz. The equations of elasticity governing this type of non-homogeneity are solved by employing a Hankel transform technique. The mixed boundary value problem associated with the indentation of the half-space by the rigid circular foundation is reduced to a Fredholm integral equation which is solved via a numerical technique. The numerical results presented in the paper illustrate the influence of the near-surface elastic non-homogeneity on the settlement of the foundation.