单檐歇山式木构古建抵抗极端烈度地震试验调查研究

为更好地保护我国古建筑,基于《单檐歇山式古建筑抗震性能振动台试验》的相关成果,研究了强震作用下我国明清官式木构古建的抗震性能,制作了与该论文相同的试验模型,进行了振动台试验。通过对模型输入烈度逐渐增强的1940年El-centro波,并考虑地震波为水平双向作用,分析了强震作用下不同构造的试验现象,开展了详细的震后调查,获得了不同构造在强震作用下的抗震性能和震害机制。结果表明:强震作用下,我国明清官式木构古建的振动形式表现为柱架、斗拱、梁架及屋顶的近似同步往复摇摆;主要震害包括柱底偏移、榫卯节点开裂、拔榫、斗拱偏移及错位、额枋-垫板分离、墙体倒塌等,但承重木构架受损不严重,结构未产生倒塌。其良好抗震性能的原因与古建筑的构造特征密切相关。     

贯入法原位测试夯土遗址表面强度的适用性和方法研究

表面强度是夯土遗址重要的测试指标和加固效果的评价依据。常规的强度测试方法受到取样和运输等因素的制约，不适用于作为夯土遗址如夯土补筑、表面加固等措施的效果评估方法。贯入法是成熟的砂浆强度检测方法，通过改装砂浆贯入仪降低了仪器量程；制作夯土样、室内试验验证了测试的较高精度；标定了夯土样贯入深度测量值与抗压强度的幂函数关系，确定了测强曲线。在夯土遗址现场开展原位测试，分析了布点密度对测试结果精度的影响，并利用测强曲线推算了测试区域的表面抗压强度。本研究提出了一套集“仪器改装-室内标定-现场高密度布点测试”为一体的夯土遗址表面强度评估方法，为土遗址加固效果的评价体系建设提供了参考价值。     

中俄双边旅游与进出口贸易互动关系的实证研究

以1998-2011年中俄两国旅游与贸易数据为基础,利用格兰杰因果关系检验发现俄国出境旅游是进出口贸易的单向格兰杰原因,中国进出口贸易是出境旅游的单向格兰杰原因。旅游与贸易互动关系研究结果表明:俄国出境旅游对进出口中国贸易均有着明显的推动作用,并对进口贸易的推动作用要明显强一些;中国进出口贸易对出境俄旅游都有明显的促进作用,进口贸易的促进作用要略强一点。俄罗斯断面看,占中国入境旅游比对对华贸易依存度有一定影响;中国断面看,中国对俄贸易依存度对出境俄旅游偏好和占俄入境旅游比影响均较大。两国旅游与贸易的互动性差异特征分析能为两国双边旅游与贸易良性互动发展提供相应参考。     

Natural‐gradient tracer experiments in epikarst: a test study in the Acqua dei Faggi experimental site,southern Italy

Two natural‐gradient tracer experiments were carried out using borehole fluorometers in order to characterize the internal structure of epikarstic horizons and analyze subsurface flow within these high‐conductivity layers. The experiments were carried out in a test site in southern Italy where the epikarst is made up of an upper part with pervasive karstification and a lower part without pervasive karstification. Injection and observation boreholes were 6.9 m apart. An initial experiment demonstrated that wider (conduits) and narrower (fractures and bedding planes) openings coexist in a well‐connected network within the lower epikarst. The adjusted aperture of the opening network (105 μm) suggests that conduits are subordinately developed. The lower epikarstic horizon is hydraulically similar to granular porous media and Darcy’s law can be applied to describe groundwater flow. A small value of longitudinal dispersivity (0.13 m) shows that variations in the velocity field in the direction of flow are less significant than those typical of carbonate systems at the same experiment scale. A second experiment demonstrated that longitudinal dispersivity (2.42 m) in the upper epikarst is in agreement with findings in other carbonates at the same experiment scale. However, despite the higher dispersivity and more pervasive karstification, the mean tracer velocity (3.7 m day^?1) in the upper epikarst is slightly lower than the velocity in the lower epikarst (13.6 m day^?1).     

自贡盐业铁工具的防锈保护

通过对馆藏盐业铁工具的锈层性状及结构的检测分析,并结合当地环境气候特征,认为其继续锈蚀的机制是电化学循环机制,提出除去有害锈、涂料封护的CLFJ防锈法。CLFJ防锈法处理生成的表面膜经防锈性检测,耐CuSO_4滴液、耐盐水性及耐水性指标全部合格,经模拟自然暴露3年条件下工业大气浸蚀的加速实验表明,馆藏条件下防锈时效性指标达5年以上;同时,表面膜呈现出贴近原貌的铁锈色。     

Variability and sampling strategy of cave wall concretion: Case study of the moonmilk found in Leye Cave (Dordogne)

Cave Art is a fragile testimony of past human societies and the development of modern behaviours. In limestone caves, moonmilk commonly endanger the artworks. It is a calcite deposit with a large variability of chemical composition and morphological structures and it hosts numerous microbial communities. The possibility to characterize this deposit in the field would aid in a better understanding of cave behaviour and allow the setting up of proper conservation measures. The present study analyses the variability of a moonmilk strip of metric size in Leye Cave in the Vézère Valley (Dordogne, France). The cave was not ornate and was selected as a laboratory cave in which in‐situ observations and micro‐sampling could be carried out, before they were performed in cavities hosting parietal artworks. Scanning electron microscope (SEM) observations of 24 samples allowed, for the first time, an investigation of the variability of moonmilk deposits over the same wall of a few metres dimension. The observations highlighted the low variability of the moonmilk at the microscopic scale when regarding the chemical composition and morphological structures, despite significant macroscopic diversity, thus providing insights into how to optimize the sampling strategy of moonmilk in ornate caves.     

应县木塔结构监测与试验分析研究综述

应县木塔历史悠久,结构复杂,其主要结构构件及构造做法基本上保留了原建时期的面貌,是研究我国早期古代建筑技术及大木制度的重要实物遗存,具有独特的艺术价值和极高的科学价值和成就。然而,由于年久失修。再加上民国时期的错误修缮和战争年代的炮弹袭击以及后来多次地震的损伤累积,当前,应县木塔二层明层结构倾斜变形严重,底部三层结构病害缠身,结构亟须修缮加固。近80年来,国内数十家单位参与应县木塔保护和研究工作,取得一些成果,为制定应县木塔保护方案提供了理论依据和基础数据。本文围绕应县木塔结构试验、结构计算及结构监测等几个方面的工作,梳理和归纳了应县木塔结构监测与试验分析的研究现状,并提出现存问题和建议,供相关研究和技术人员参考。     

四川大邑县高山古城遗址宝墩文化先民牙本质序列的碳氮稳定同位素分析

通过对成都平原新石器时代晚期(约4500BP)高山古城遗址出土人骨和牙齿进行稳定同位素分析,重建个体层面上先民的生活史,以及断奶行为、生活方式等重要信息。人骨同位素数据(δ13C:-19.6‰^-18.0‰)表明,该人群主要以C3类食物为食,这应当与当时较为发达的稻作农业相关。然而,该群体的个体牙本质序列的同位素数据(δ13C:-19.6‰^-15.0‰)较骨骼更高,显然这是因为C4类食物(粟黍作物)在其先民断奶过程和童年早期起到了重要作用。此外,个体牙本质序列氮稳定同位素比值的变化趋势,显示总体上先民的断奶行为在2.5~4岁之间完成。这一研究成果,为探讨稻粟混作区的粟作农业在先民生活方式中的重要地位以及其向南方传播和扩散的进程提供了新的研究视角。     

Experimental Investigation on the Seismic Behavior of the Semi-Rigid One-Way Straight Mortise-Tenon Joint of a Historical Timber Building

ABSTRACT

This article aims to disclose that the deformation and damages of the one-way straight mortise-tenon (OWSMT) joint, the key force transmission connection of traditional wood buildings, lead to a significant reduction in structural safety of ancient timber structure. For this purpose, the damage of mortise joint in practical engineering wassimulated by controlling the gap and width between mortise and tenon. A total of 23 groups of scaled 1:2 OWSMT joint specimens were fabricated and tested subjected to cyclic loadings, and the hysteretic curves of OWSMT joint with different damage degrees were obtained. Through skeleton curves, stiffness degradation curves, and equivalent viscous damping curves of the OWSMT joint, the seismic performance of damaged wood joints was quantitatively analyzed. The results show that, with the increase in the gap between the tenon and the mortise, the slip between them became increasingly obvious, the fullness and peak of the hysteresis curve gradually decreased, the gradient of the skeleton curve also dropped, and both the stiffness degradation curve and the equivalent viscous damping curve are gradually reduced. The research findings shed new light on the seismic assessment of aging timber buildings.     

Structural Assessment of Ancient Masonries before and during a Rehabilitation Process

ABSTRACT

The rehabilitation of old buildings requires detailed knowledge of the mechanical characteristics and stress state of the structural elements, which play an important role in the intervention process. In this sense, non-slightly destructive tests can estimate structural characteristics with good precision at relatively low costs. Consequently, this article presents a device, based on the flat jack technique, applied to continuous stress monitoring over time. It also focuses on the onsite determination of service stresses and its continuous monitoring in several masonry buttresses of a historic building, as well as the assessment of the structural safety before, during, and after an intervention process. A brief analysis of the research is performed, and the motivation and the methodology adopted are described. Finally, the evolution of the measurements recorded and the analysis of the results achieved are detailed. The study enabled recommendations to be made to the intervening agents that guarantee structural safety.