湖南利民煤矿煤与瓦斯突出量级程度划分及其应用研究

根据煤与瓦斯突出的地质条件,对煤岩体系中的弹性潜能、瓦斯内能、采场附加应力积聚的能量分别进行了定性的划分,并结合弹性潜能、瓦斯内能,对煤与瓦斯突出的量级程度也尝试性地首次做出分类,并提高了原来的下限指标。对典型突出模式进行了简要地分析,为今后开展防治利民矿井煤与瓦斯突出工作提供了新的思路与对策。     

The effects of repeated earthquake ground motions on the non‐linear response of SDOF systems

In many parts of the world, the repetition of medium–strong intensity earthquake ground motions at brief intervals of time has been observed. The new design philosophies for buildings in seismic areas are based on multi‐level design approaches, which take into account more than a single damageability limit state. According to these approaches, a sequence of seismic actions may produce important consequences on the structural safety. In this paper, the effects of repeated earthquake ground motions on the response of single‐degree‐of‐freedom systems (SDOF) with non‐linear behaviour are analysed. A comparison is performed with the effect of a single seismic event on the originally non‐damaged system for different hysteretic models in terms of pseudo‐acceleration response spectra, behaviour factor q and damage parameters. The elastic–perfect plastic system is the most vulnerable one under repeated earthquake ground motions and is characterized by a strong reduction of the q‐factor. A moment resisting steel frame is analysed as well, showing a reduction of the q‐factor under repeated earthquake ground motions even larger than that of an equivalent SDOF system. Copyright © 2002 John Wiley & Sons, Ltd.     

基于简化的Pride理论模拟声电效应测井响应

针对声电效应测井问题，提出了一种全波列数值模拟方法.该方法忽略声电效应测井 时转换电场对声场的影响,并将电场视为似稳场.采用点声源模型，依据Biot理论得出了井外 孔隙介质声场的表达式，运用这些表达式和似稳电场近似方法，导出了声电效应测井时转换 电场的计算公式.在计算出的转换电场波形中，有伴随斯通利波的电场、伴随纵波和横波的 电场、和临界折射电磁波场.在25kHz以下的频率范围内，依据这种方法计算出来的声电转换 波波形与依据完整Pride理论计算的波形一致.     

Characterization and reconstruction of a rock fracture surface by geostatistics

It is well understood that, in studying the mechanical and hydromechanical behaviour of rock joints, their morphology must be taken into account. A geostatistical approach has been developed for characterizing the morphology of fracture surfaces at a decimetre scale. This allows the analysis of the spatial variability of elevations, and their first and second derivatives, with the intention of producing a model that gives a numerical three‐dimensional (3D) representation of the lower and upper surfaces of the fracture. Two samples (I and II) located close together were cored across a natural fracture. The experimental data are the elevations recorded along profiles (using recording steps of 0.5 and 0.02 mm, respectively, for the samples I and II). The goal of this study is to model the surface topography of sample I, so getting estimates for elevations at each node of a square grid whose mesh size will be, for mechanical purposes, no larger than the recording step. Since the fracture surface within the sample core is not strictly horizontal, geostatistical methods are applied to residuals of elevations of sample I. Further, since structural information is necessary at very low scale, theoretical models of variograms of elevations, first and second derivatives are fitted using data of both that sample I and sample II. The geostatistical reconstructions are computed using kriging and conditional simulation methods. In order to validate these reconstructions, variograms and distributions of experimental data are compared with variograms and distributions of the fitted data. Copyright © 2002 John Wiley & Sons, Ltd.     

'After-the-fact causality': a different direction for cultural geography

Cultural geography might benefit from consideration of radical behaviourism and from interpretation and application of the concepts of behaviour analysis. The basic concept is that of operant conditioning, referring to the environment reinforcing behaviours that are most adaptive and effective in achieving reinforcers and avoiding aversive stimuli. The concept of rule-governed behaviour facilitates incorporation of cognition into behaviour analyses, accommodating the fact that many consequences are delayed. These concepts are applied in an analysis of nineteenth-century Mormon settlement in the American West. This argument for an objectivist approach is laden with social scientific baggage not favoured in contemporary cultural geography.     

岩石波速温度和压力系数的测量方法及其应用

概述了高温高压实验技术在研究地球深部物质组成和结构等方面所起的作用，认为它是把地球物理模型同地球深部物质组成结合起来必不可少的一个中间环节，通过分析典型的试验结果，介绍了在实验室测定岩石波速温度系数（ρ↓V/ρ↓T）P、压力系数（ρ↓T／ρ↓P）T和岩石本征波速（VO）的方法，以及运用它们进行波速外推的原理，结合前人工作实例，阐明了将此技术与地质及地球物理研究结合，为地球物理测深资料的解释提供实验约束的研究思路，针对在前人工作中实验参数及实验结果存在差异的现象，着重探讨了实验条件和流程对实验结果的影响，认为，在用回归方法计算（ρ↓V／ρ↓P）T时，通常应在大于300MPa的压力段上采集实验数据，以消除岩石内部先存微裂隙的影响；在计算（ρ↓V／ρ↓P）T时，为抑制热裂隙的产生，还应满足不小于1MPa/℃的压力增量；另外，测定（ρ↓V／ρ↓T）P时，实验温度不宜太高，以避免引起岩石内部的矿物相变和物态变化。     

深层地震勘探的地震波传传播理论研究前景

深层地震勘探为地震波传播理论研究提出了新的挑战和机遇。深层地震勘探的主要难点是上覆层的影响甚大，使后续的处理有隔靴挠痒之感，必须应用波场延拓消除上覆层影响。深层波速的高速性和横向不均匀性决定了大角散射和弹性波处理方法的重要性。本文具体评述了深层地震勘探的主要方法对策，深入探讨了波场延拓的李群方法和弹性反演的某些问题，目的在于为深化深层地震提供新的研究手段和方法。     

空气污染对城市活力的影响及其建成环境异质性——基于大数据的分析

建设充满活力的城市空间得到地理和城乡规划学者的广泛关注。随着空气污染问题的加剧,空气质量影响居民在城市空间中的活动,但鲜有研究考察空气污染与城市活力的定量关系。基于广州市2019年新浪微博签到记录、日气象和空气质量数据、以及建成环境数据,本研究构建以街道为空间单元、以天为时间单元的面板数据,通过标准差椭圆（SDE）以及面板回归模型测度空气污染对城市活力的抑制效应以及该抑制效应在不同建成环境上的异质性。研究得到以下结论：① 城市活力SDE面积随空气质量指数（AQI）上升而收缩,轻度污染和中度污染的城市活力SDE面积仅为空气质量优的约80%和30%。② 运用空间面板回归模型控制街道的空间关联性后,空气质量指数（AQI）对城市活力具有明显负向影响,AQI每增加1个单位,日活动强度减少约0.10次/10 km²;当空气质量恶化到中等污染后,AQI每增加1个单位,日活动强度减少约0.14次/10 km²。③ 空气污染对城市活力的抑制效应在不同建成环境上存在异质性,POI密度、离城市中心距离强化空气污染对城市活力的抑制效应,而地铁站密度、道路交叉口密度、土地利用混合度则弱化空气污染对城市活力的抑制效应。本研究有助于更好厘清空气污染、建成环境与城市活力的关系,并为优化建成环境以缓减空气污染对城市活力抑制效应提供分析支撑。     

Analytical prediction of seismic behaviour for concentrically-braced steel systems

This paper presents an analytical model for the inelastic response analysis of braced steel structures. A model is first presented for the behaviour of steel struts subjected to cyclic axial load, which combines the analytical formulation of plastic hinge behaviour with empirical formulas developed on the basis of experimental data. The brace is modelled as a pin-ended member, with a plastic hinge located at the midspan. Braces, with other end conditions, are handled using the effective length concept. Step-wise regression analysis is employed, to approximate the plastic conditions for the steel UC section. Verification of the brace model is performed on the basis of quasi-static analyses of individual struts and a one-bay one-storey X-braced steel frame. The comparison of analytical and experimental data has confirmed that the proposed brace model is able to accurately simulate the cyclic inelastic behaviour of steel braces and braced systems. A series of dynamic analyses has been performed on two-storey V- and X-braced frames to study the influence of brace slenderness ratio on the inelastic response, and to look at the redistribution of forces in the post-buckling range of behaviour of CBFs. Recommendations have been made as to the estimation of maximum storey drifts for concentrically-braced steel frames in major seismic event. © 1997 John Wiley & Sons, Ltd.     

A THERMO-VISCOPLASTIC CONSTITUTIVE MODEL FOR CLAYS

The effect of heat on clay behaviour is characterized by non-linearity and irreversibility. Due to the complex influence of temperature, thermomechanical factors have to be taken into account for the numerical simulation of the behaviour of such materials. A cyclic thermo-viscoplastic model is developed for this purpose. It includes thermal hardening and the evolution of yield surfaces with temperature. From the physical point of view, it is built on the basis of available experimental results for a temperature range in which no phase change occurs. Conceptually, it is the generalization of an isothermal multimechanism cyclic model. A thermoplastic formulation of the model is also derived. The results obtained from numerical simulations compare well with experiments. © 1997 by John Wiley & Sons, Ltd.