Water concentrations and hydrogen isotope compositions of alkaline basalt-hosted clinopyroxene megacrysts and amphibole clinopyroxenites: the role of structural hydroxyl groups and molecular water     

István Kovács  Attila Demény  György Czuppon  Christophe Lécuyer  Francois Fourel  Qun-Ke Xia  Jia Liu  Zsanett Pintér  Edit Király  Kálmán Török  Ábel Szabó  Etienne Deloule  György Falus  Tamás Fancsik  Zoltán Zajacz  Judit Sándorné Kovács  Beatrix Udvardi 《Contributions to Mineralogy and Petrology》2016,171(5):38

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Dynamic response of a group of flexible foundations to incident seismic waves   总被引：1，自引：0，他引：1  

L.G. Tham  J. Qian  Y.K. Cheung 《Soil Dynamics and Earthquake Engineering》1998,17(2):127-137

The dynamic response of a finite number of flexible surface foundations subjected to harmonic incident Rayleigh or SH waves is presented. The foundations are assumed to be resting on an elastic half-space. The results show that the foundation stiffness has a marked effect on the vertical response, while there is only a minor effect on the horizontal displacements. In general, the dynamic response decreases with increasing foundation stiffness. In cases of Rayleigh wave incidence, the existence of an adjacent foundation generates a certain amount of horizontal response in the direction perpendicular to the incident wave and subsequently causes the system to undergo a torsional motion; while in cases of horizontally incident SH waves, a vertical response has been observed and its magnitude is comparable to the response in the direction of the incident wave.  相似文献   

Stresses and excess pore pressure induced in saturated poroelastic halfspace by moving line load   总被引：2，自引：0，他引：2  

B. Jin  Z. Q. Yue  L. G. Tham 《Soil Dynamics and Earthquake Engineering》2004,24(1):25-33

This paper examines stresses and excess pore fluid pressure that are induced in a saturated poroelastic soil of halfspace extent by a concentrated line load. The line load is moving at a constant velocity along the surface of the poroelastic halfspace. The governing equations for the proposed analysis are based on the Biot's theory of dynamics in saturated poroelastic soils. The governing partial differential equations are solved using Fourier transforms. The solutions for the stresses and excess pore pressure are expressed in the forms of inverse Fourier transforms. The numerical results are obtained by performing the numerical inversion of the transform integrals. A parametric study is presented to illustrate the influences of the velocity of moving load and the poroelastic material parameters on the stresses and excess pore pressure. At a high velocity, the maximum values of the stresses in a poroelastic halfspace are smaller than those in an elastic solid, whilst at a low velocity the stresses in a poroelastic halfspace are larger than those in an elastic halfspace. The potential of diffusivity has an important influence on the stresses and excess pore pressure.  相似文献   

香港岩石的硬度与点荷载指标和强度的关系   总被引：5，自引：0，他引：5  

谭国焕  李启光  徐钺 《岩土力学》1999,20(2):52-56

无损硬度测试——施密特锤及肖氏硬度实验和点荷载试验是三种经常用来间接测定岩石强度指标的方法。目前很多学者已提出了不同的经验关系,这些关系主要是把硬度指标、点荷载指标和单轴抗压强度、单轴抗拉强度与间接拉伸强度联系起来。但是在应用这些关系时,必须首先用当地的岩石特性数据加以验证,查看地质变化的影响,才可确保使用无误。本文的主要目的是根据大量香港岩石（包括花岗岩、石灰岩、大理岩和凝灰岩）的实验数据,提出一套适用于香港地区岩石的经验关系,另外也对其他经验关系作了考证。  相似文献   

《地质论评》对新赐稿件的形式审查要点     

编辑部 《地质论评》2020,66(2):66020409-66020409

正(1)前言节应当交代清楚本文所研究对象的历史、现状、存在问题及本文的创新之处,点出本文的重要意义。(2)结论节,指出通过本文研究获得的新材料或新认识。(3)参考文献我刊用著者-年制,文中提到的文献要一一列于文献表中,列于文献表中的文献一定要是正文(含图或表)中提到的。为方便专家审查和编辑,我刊要求送审稿必须用著者—年制。(4)可以,也可以不,参照我刊其他一般要求(见"推荐文献"栏下)。 如:终稿修改及提供材料要求, 图件修  相似文献   

Analysis of footing resting on non-homogeneous soil by double spline element     

L. G. Tham 《Computers and Geotechnics》1988,5(4):249-268

A numerical method is proposed for the analysis of rectangular footing resting on an elastic soil layer. The footing is represented by double spline elements and the elastic soil medium by finite layers. The effect of the rigidity of footing and the non-homogeneity of the soil on the behaviour of such foundation system is investigated, and the results are presented in form of design charts such that they may be used for hand calculation for the estimation of the settlement of footings for a wide range of practical cases.  相似文献   

Obliquity-driven mountain permafrost-related fluvial magnetic susceptibility cycles in the Quaternary mid-latitude long-term (2.5 Ma) fluvial Maros Fan in the Pannonian Basin     

Zoltán Püspöki  Philip L. Gibbard  László Ferenc Kiss  Richard W. McIntosh  Edit Thamó-Bozsó  Zita Krassay  Bálint Szappanos  Vera Maigut  Péter Kovács  Dominik Karácsony  Ferenc Stercel  Ferenc Visnovitz  Krisztina Demény  László Bereczki  Teodóra Szőcs  Ágnes Rotár-Szalkai  Tamás Fancsik 《Boreas: An International Journal of Quaternary Research》2023,52(3):402-426

Magnetic susceptibility (MS) of the Quaternary long-term mid-latitude Maros fluvial fan (Pannonian Basin) was recorded to understand the stratigraphical features of source-proximal fluvial depositional settings. Three fully cored 500-m-deep boreholes were sampled at 0.5-m intervals; low-field and frequency dependent MS were measured, and complementary hysteresis and SEM-EDAX investigations were performed on selected samples. Logged susceptibility data were also used to log correlations established by a simultaneous comparison of wireline log and laboratory measurements. Time-series analyses of the susceptibility records reveal a ~41-ka and ~100-ka cyclicity. Towards the source-distal sections the intensity of the ~41-ka cycles decreases, while that of the ~100-ka cycles remains strong. Stratigraphical and spectral similarities were observed between the Maros fluvial fan and Chinese loess records; however, based on complementary magnetic data, the magnetic phase of the Maros Fan sections is related to the detrital magnetite that originates from the catchment during early postglacial permafrost degradations. The amplification of the ~41-ka cycles can be attributed to the very high susceptibility values in source-proximal settings and to the special stratigraphical feature of the distributive fluvial systems. This comprises the increased avulsion frequency on the fluvial fans in ‘glacial recession periods’, in concert with the ‘early postglacial’ occurrence of the permafrost-related magnetite originating from the catchment. As a local phenomenon, this is significant since it records the obliquity-driven variations in permafrost development in a catchment. However, fluvial and alluvial fans are widespread depositional landforms within the Eurasian mountain range and were possibly the same during the Quaternary deglaciations. Thus, obliquity-driven magnetic susceptibility variations in source-proximal fan deposits attached or adjacent to regions of loess deposition should also be considered when scanning for potential source material of aeolian deposits.  相似文献   

Micromechanical analysis of the failure process of brittle rock   总被引：1，自引：0，他引：1       下载免费PDF全文

K. Duan  C.Y. Kwok  L.G. Tham 《国际地质力学数值与分析法杂志》2015,39(6):618-634

The failure process of brittle rock submitted to a compression state of stress with different confining pressures is investigated in this paper based on discrete element method (DEM) simulations. In the DEM model, the rock sample is represented by bonding rigid particles at their contact points. The numerical model is first calibrated by comparing the macroscopic response with the macroscopic response of Beishan granite obtained from laboratory tests. After the validation of numerical model in terms of macroscopic responses, the failure process of the DEM model under unconfined and confined compression is studied in micro‐scale in detail. The contact force network and its relation to the development of micro‐cracks and evolution of major fractures are studied. Confining pressure will prohibit the development of tensile cracks and hence alter the failure patterns. An in‐depth analysis of micro‐scale response is carried out, including the orientation distribution and probability density of stress acting on parallel bonds, the effect of particle size heterogeneity on bond breakage and the evolution of fabric tensor and coordination number of parallel bond. The proposed micromechanical analysis will allow us to extract innovative features emerged from the stresses and crack evolution in brittle rock failure process. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

A phenomenological constitutive model for rocks with shear failure mode     

G. L. Zhou  L. G. Tham  P. K. K. Lee  Y. Tsui 《国际地质力学数值与分析法杂志》2001,25(4):391-414

In this paper, a phenomenological constitutive model is proposed to simulate the stress–strain behaviours of intact rocks with shear failure mode. The model captures a wide range of behaviours of rock material such as elastic, plastic, strain softening, ‘Class II’, strain localization, elastic modulus degradation, etc. The sensitivity of the stress–strain relation on the parameters is also investigated. Typical results obtained by testing a number of granite and marble specimens are used to validate the proposed model. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Investigation of river network evolution using luminescence dating and heavy mineral analysis of Late-Quaternary fluvial sands from the Great Hungarian Plain     

Edit Tham-Bozs  Andrew S. Murray  Annamria Ndor  rpd Magyari  Edit Babinszki 《Quaternary Geochronology》2007,2(1-4):168-173

To reconstruct the evolution of Late-Quaternary river network in the southeastern part of the Great Hungarian Plain, we have used optically stimulated luminescence (OSL) and heavy mineral analysis of 25 sand samples from the upper 2–8 m of the fluvial units, complemented by four radiocarbon ages. The estimated OSL depositional ages vary between 10 and 47 ka. The heavy mineral composition of the OSL samples was compared to the compositional data of recent river sediments using cluster analysis. The new OSL and heavy mineral data show that from 47 to 10 ka ago the sediments were transported mainly from the northeast direction into the southeastern part of the Great Hungarian Plain by the ancestor of the Tisza river and its northern tributaries, and probably by another large river which also flowed northeast–southwest, parallel to the modern Tisza. Between 23 and 14 ka sediments periodically came from the east and reached the eastern part of our study area. Between 15 and 12 ka ago, sands transported from the southeast also occur in the southeastern and central part of the study area. These data suggest that the modern rivers occupied their present courses only in the last 10 ka.  相似文献