两种摩擦耗能器的比较试验研究

对两种不同形式的摩擦耗能器进行了低周反复荷载试验。工其工作性能和耗能性能，并进行了带有不同摩擦片和不带摩擦片的对比试验，分析了影响耗能器性能的因素，试验结果表明，摩擦耗能支撑具有稳定的滞回性能和极好的耗能能力，摩擦片的类型与性能对摩擦耗能支撑的性能有较大的影响。     

粉体喷射搅拌法加固软基静载荷试验研究

粉体喷射搅拌法是一种加欠土地基的新技术。通过不同类型粉喷桩复合地基的静载试验分析研究，得出了桩土应力比、地基承载力及桩土分担荷载等实测值，并通过实测数据核正理论公式中的经验系数，得到了粉喷桩复合地基在荷载作用下的一些应力－应变规律，旨在为发展和推广此法提供理论依据。     

Transient groundmotion in an elastic homogeneous halfspace to blasting loading

A closed-form transient solution to blasting loading is presented. The blasting loading is modelled as a finite sheet dilatational source, rather than a finite line, so that the dimensions of the explosives are taken into account in two directions, i.e. one in the horizontal direction and the other in the vertical direction. The solution is obtained by using Laplace transform, with respect to the time, and Fourier transform with respect to the coordinates. Inverse Laplace transform is implemented analytically. The final solution is expressed in double integral form. The solution can be used to determine groundmotion in studying blasting impacts on underground or aboveground structures.     

High-pressure metamorphism caused by magma loading in Fiordland, New Zealand

Cretaceous granulite facies metamorphism in the Fiordland area of New Zealand has distinctive mineralogical, textural and structural features that set it apart from most other regional metamorphic belts. The metamorphism, developed over a 30×150-km area and the consequence of a 20-km-thick increment to crustal thickness, is closely associated in space and time with a large plutonic complex, the Western Fiordland Orthogneiss (WFO). Although temperatures and pressures as high as 700  °C and 12  kbar were attained, the metamorphic overprint on earlier low-pressure assemblages is weak and incomplete. Little strain accompanied the metamorphism. The temperature threshold at which metamorphic recrystallization is recorded is over 500  °C. Zoned garnets are preserved at unusually high temperatures, indicating duration of metamorphism on the order of 10 times shorter than in most other regional terranes. This pattern of features bears close similarity to metamorphism in the Coast Plutonic Complex in North America, where a mechanism of 'magma loading' has been invoked. In Fiordland, the high-pressure metamorphism can be explained by depression of country rock under a crustal zone that is inflated by intrusion of the WFO. Regional structure of the WFO as a horizontally sheeted complex suggests that the pluton was emplaced by vertical displacement of country rock, and supports the magma loading model.     

动力荷载作用下软粘土的残余变形计算模式

在试验结果的基础上，提出了动力荷载作用下计算软粘土残余变形的模式。并将计算结果与不排水和部分排水情况下观测到的孔隙水压力及残余应变进行比较，两者具有较好的吻合性。本文所提出的计算模式可用来估算动力荷载（例如地震荷载、交通荷载）作用下建于软粘土地基上的建筑物及其它设施所产生的附加沉降。     

VRML文件数据的数据库存储方案研究

本文介绍了VRML技术及其数据格式,设计并实现了一个数据库,用以存储虚拟现实和3D G IS所需要的三维数据。同时,首次提出一种数据转换算法,抽取VRML文件中同一建筑物的点、面数据信息,存入数据库,并以某种方式优化数据库,动态加载数据,以加快应用程序的运行速度。     

Correlation Analysis of the Ultrasonic Emission from Loaded Rock Samples – the Study of Interaction of Microcracking Nucleation Centres

Summary.  The locations of fractures within loaded rock samples are distributed irregularly because of the presence of inhomogeneities in the rock sample, the existence of primary microcracks and non-uniformly distributed stress. In the case of brittle fracture, the positions of these fractures can be determined by locating the foci of ultrasonic events that occur during fracturing. In some cases, the foci cluster into clouds that are restricted spatially and are referred to as nucleation centres. The purpose of this research was to determine the mutual relationship between the various nucleation centres, by cross-correlating the time-series of ultrasonic events produced by microcracking in the individual, separate nucleation centres. An additional goal was to assess the effect of the existence of such nucleation centres on the autocorrelation parameters. This study showed that the separate nucleation centres did not appear to influence one another even during the final stages of fracturing. Until now, autocorrelation analysis of acoustic emission time sequences has been applied to evaluate the mutual influence of individual events that occur in the whole sample volume, regardless of their location. In a previous study, it was found that before the total fracturing of the sample, the autocorrelation parameters changed significantly due to the increase in mutual relationship between successive events. In this study the separated nucleation centres determined by locating the ultrasonic events were subjected to autocorrelation analysis. It was demonstrated that, in the case of critical loading of the sample, the mutual influence between the events of a given nucleation centre can be observed. The experiments have demonstrated that the autocorrelation has a precursory nature and have shown that there is a significant difference in the autocorrelation parameters calculated between the set of all recorded events, and the specific sub-set. These differences must be taken into account when applying statistical predictions, for example, in the study of rock bursts. Author’s address: Jan Vilhelm, Charles University in Prague, Albertov 6, 128 43 Prague, Czech Republic     

Complexities of rock fracture and rock friction from deformation of Westerly granite

A series of rock friction experiments has been carried out to study the complexities in rock fracture and rock friction. Intact Westerly granite samples were loaded to shear failure in a laboratory polyaxial loading apparatus. The resultant fractured samples were reloaded to cause frictional sliding. Both polyaxial loading (₁ > ₂ > ₃ > 0) and equal confining condition (₁ > ₂ = ₃ > 0) were used. The deformation processes were monitored by macroscopic axial stress-strain, optical holography, and ultrasonic velocity measurements.Intense localized deformation along the fracture occurred very early in the loading of fractured samples. Contacts on the fracture surfaces continuously broke during loading. No acoustic velocity anomaly was observed for the fractured sample, in contrast to a 25% drop in the velocity before the failure of the corresponding intact sample. The current study and previous research suggest that the deformation localization is an important process in governing the instability of rock friction. Instability analysis of rock friction needs to include not only the deformation processes along the sliding surfaces, but also those adjacent to the fractures such as the localized deformation along the fractures observed in the current study. The instability analysis of rock friction with rate- and state-dependent friction laws does not specifically include the deformation localization adjacent to the faults and thus ignores an important class of instability as described byRudnicki (1977).A dependence of frictional strengths on the stress components normal to the sliding and in the plane of the fracture surface was observed. This dependence can be understood by considering the loading of the irregular fracture surface under polyaxial loading conditions. This observation requires the friction laws in the macroscopic scale to be modified for those cases where the three principal stresses (₁, ₂, and ₃) are significantly different.     

Dynamic instability of laminated sandwich plates subjected to in-plane partial edge loading

The dynamic instability of laminated sandwich plates subjected to in-plane partial edge loading is studied for the first time using an efficient finite element plate model. The plate model is based on a refined higher order shear deformation plate theory, where the transverse shear stresses are continuous at the layer interfaces with stress free conditions at plate top and bottom surfaces. Interestingly the plate model having all these refined features requires unknowns at the reference plane only. However, this theory requires C¹ continuity of transverse displacement, which is difficult to satisfy arbitrarily in any existing finite element. To deal with this, a new triangular element developed by the authors is used in the present paper.     

Components of suction caisson capacity measured in axial pullout tests

Suction caissons are the foundation of choice for offshore structures in deep water. Systematic study of caisson behavior is relegated to the laboratory due to the high cost of full-scale testing. Our laboratory caisson was installed in normally consolidated clay using dead weight and suction. Tensile axial capacity was measured with the top cap vented or sealed, and with the soil undrained or drained. For the common case of rapid pullout with a sealed top, the test results indicate an external side resistance factor (α) of 0.5–0.8 and a reverse end bearing factor (N_c) of 13–21.