声频应力波法检测土遗址加固用玻璃纤维锚杆锚固质量初探

土遗址锚杆锚固质量一直是土遗址加固工程中关注的重点问题。目前,土遗址领域均采用具有破坏性的拉拔试验对其进行检测。基于土遗址的文物属性,本研究尝试利用无损检测技术评价土遗址加固用玻璃纤维锚杆的锚固质量。通过锚杆无损检测仪与拉拔仪分别对甘肃省红沙堡遗址与永泰城址加固工程中的玻璃纤维锚杆锚固系统进行检测。比较实际测量杆长与仪器测量杆长结果,得出杆长指标可以判断无损检测仪所测结果的真实性。无损检测仪得出的检测波形衰减规律显著,对比相应锚杆的拉拔试验的评价结果,证实了声频应力波法在土遗址玻璃纤维锚杆锚固系统无损检测中的适用性。本研究结果将为评价土遗址加固用玻璃纤维锚杆锚固质量提供可靠的依据。     

大雁塔盐害及劣化模拟试验研究

易溶盐富集是陕西西安大雁塔砖体表面风化、结构破坏、强度衰减的主要原因。为分析盐害对大雁塔砖体结构、强度的影响机理,采用以饱和硫酸钠溶液为介质,对大雁塔砖体进行易溶盐结晶循环模拟劣化试验。在Na₂SO₄反复结晶、溶解过程中,测定试样的质量、波速及单轴抗压强度等指标,分析其变化规律。结果表明,在盐害作用下,试验砖体表现出与塔体表面类似的风化破坏现象;Na₂SO₄晶体在试样孔隙内不断发育,晶体挤压效应导致孔隙率增大,内部结构破损;质量、波速、单轴抗压强度随循环的次数呈先增加后减小的变化规律。砖体对盐害耐受力约为砖体质量的0.5%。     

旅游业与我国经济增长关系的实证分析

旅游业与国民经济增长之间的关系一直是有关学者研究的对象,这也导致了对旅游业地位的不同认识。本文利用历史数据对改革开放以来中国居民旅游消费支出与经济增长之间的关系作出判断,认为我国旅游业与经济增长之间并不存在稳定的因果关系。文章对产生这种现象的原因进行了分析,并提出了相关政策建议。     

Rotational behavior of degraded traditional mortise-tenon joints: experimental tests and hysteretic model

This article presents the results of an experimental study on the rotational behavior of degraded Chinese traditional mortise-tenon joints with different degradation types and different degradation degrees. Six joint specimens degraded through artificially simulated method, were tested by reversed cyclic loading, from which the moment-rotation curves were obtained. The results indicated that the rotational behavior of these joints is semi-rigid, the hysteretic curve shapes of degraded joints are same to that of joint without degradation. The maximum moment, yield moment, and initial rotational stiffness of degraded joints decreases as the degraded degree increases, whose empirical degradation relationships were obtained based on the test data. A hysteretic model for degraded traditional mortise tenon joints was proposed. Experimental results were used to validate the proposed hysteretic model. Good agreement between predictions and tests was observed.     

In Situ Characterization of Rammed Earth Wall Renders

The Algarve region in southern Portugal has one of the most significant rammed earth construction legacies in the country. This construction method is characterized by its high susceptibility to water damage and external renderings are essential to the longevity of these constructions. This study collects and organizes data that provides the basis for the conservation and repair of renderings. Five earth buildings from western Algarve were selected to represent this heritage and its diversity of composition and susceptibility to water damage. Some of their commonest anomalies result from the interaction between the earth substrate and the traditional external renderings, given their distinct characteristics and behavior. The selected sample is described and the mechanical strength of the rammed earth walls and their renderings are evaluated through in situ tests. Samples of the external renderings and earth substrate of the five buildings comprising the sample were also collected and characterized in the laboratory. The characteristics of these two materials and their behavior as an assembly were analyzed. The results of the in situ and laboratory tests are compared and the viability of using a method based on in situ tests for the wider characterization of the type of construction under analysis evaluated.     

Hydraulic observations from a 1 year fluid production test in the 4000 m deep KTB pilot borehole

A long‐term pump test was conducted in the KTB pilot borehole (KTB‐VB), located in the Oberpfalz area, Germany. It produced 22 300 m³ of formation fluid. Initially, fluid production rate was 29 l min^?1 for 4 months, but was then raised to an average of 57 l min^?1 for eight more months. The aim of this study was to examine the fluid parameters and hydraulic properties of fractured, crystalline crusts as part of the new KTB programme ‘Energy and Fluid Transport in Continental Fault Systems’. KTB‐VB has an open‐hole section from 3850 to 4000 m depth that is in hydraulic contact with a prominent continental fault system in the area, called SE2. Salinity and temperature of the fluid inside the borehole, and consequently hydrostatic pressure, changed significantly throughout the test. Influence of these quantities on variations in fluid density had to be taken into account for interpretation of the pump test. Modelling of the pressure response related to the pumping was achieved assuming the validity of linear Darcy flow and permeability to be independent of the flow rate. Following the principle ‘minimum in model dimension’, we first examined whether the pressure response can be explained by an equivalent model where rock properties around the borehole are axially symmetric. Calculations show that the observed pressure data in KTB‐VB can in fact be reproduced through such a configuration. For the period of high pumping rate (57 l min^?1) and the following recovery phase, the resulting parameters are 2.4 × 10^?13 m³ in hydraulic transmissivity and 3.7 × 10^?9 m Pa^?1 in storativity for radial distances up to 187 m, and 4.7 × 10^?14 m³ and 6.0 × 10^?9 m Pa^?1, respectively, for radial distances between 187 and 1200 m. The former pair of values mainly reflect the hydraulic properties of the fault zone SE2. For a more realistic hydraulic study on a greater scale, program FEFLOW was used. Parameter values were obtained by matching the calculated induced pressure signal to fluid‐level variations observed in the KTB main hole (KTB‐HB) located at 200 m radial distance from KTB‐VB. KTB‐HB is uncased from 9031 to 9100 m and shows indications of leakage in the casing at depths 5200–5600 m. Analysis of the pressure record and hydraulic modelling suggest the existence of a weak hydraulic communication between the two boreholes, probably at depths around the leakage. Hydraulic modelling of a major slug‐test in KTB‐HB that was run during the pumping in KTB‐VB reveals the effective transmissivity of the connected formation to be 1 to 2 orders of magnitude lower than the one determined for the SE2 fault zone.     

Blind tests shed light on possibilities and limitations for identifying stone tool prehension and hafting

Prehensile wear has never formed the focus of a blind test in microwear studies and doubts remain about the formation, identification and interpretation of diagnostic prehension and hafting wear. The results of the presented blind tests demonstrate that prehension and hafting traces do form and that their formation is sufficiently systematic and patterned to allow valid and reliable interpretations. A combined approach, involving macroscopic, low power and high power analyses, is suggested as the most meaningful approach for consistent inferences.     

From Alloy Composition to Alloying Practice: Chinese Bronzes

We propose a new methodology based on standard statistical processes for displaying and rigorously comparing the alloy composition of archaeological bronze alloys. Although traditional approaches using visual comparisons of histograms of alloying elements in an assemblage of archaeological objects are adequate for observing differences between these distributions, we argue that differences in sample size cannot be adequately accounted for without using a statistical approach. We demonstrate this methodology by comparing the alloy composition of bronzes from the sequence of Bronze Age cultures in Central China—Erlitou, Erligang (Zhengzhou, or early Shang), Anyang (late Shang) and Western Zhou. We suggest that this approach allows the identification and rigorous comparison of ‘regional alloying practices’, which in turn enables us to link the alloy composition of the objects with the intentions and skills of foundry workers.