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301.
岩体水力学概述 总被引:8,自引:0,他引:8
仵彦卿 《地质灾害与环境保护》1995,6(1):57-64
本文通过伙在工程活动与地质环境相互作用分析,揭示了人类工程、岩体与地下水之间的关系;论述了岩体水力学的研究对象,学科地位,研究内容以及研究方法。 相似文献
302.
本文在考察了节理化岩体的断裂力学特征的基础上,结合现代分形几何原理,建立起追踪裂纹裂分形模型,对不连续岩体的断裂韧性的分形效应进行了深入研究,并通过压剪试验得到难。 相似文献
303.
Strength equilibrium slopes are rock slopes whose gradient θ and rock mass strength (RMS) are in adjustment. The identification of such slopes depends on the accurate specification of the strength equilibrium envelope. Previous attempts to delimit the envelope are reviewed and modifications are proposed that permit its more rigorous statistical definition. Because θ can be measured much more reliably than RMS, the structural relation between these variables is estimated by regressing RMS on θ, and the strength equilibrium envelope is defined by the 95 per cent confidence limits. The analysis is performed on a data set of 268 rock slopes, representing all the data on RMS and θ hitherto employed in published studies of strength equilibrium slopes. 相似文献
304.
土木工程结构的双层多重调谐质量阻尼器控制策略 总被引:4,自引:0,他引:4
李春祥 《地震工程与工程振动》2005,25(1):113-119
为能得到用尽可能少的调谐质量阻尼器(TMD)组成有效性和鲁棒性高的多重调谐质量阻尼器控制系统,本文提出了一种适用于土木工程结构的新控制策略——双层多重调谐质量阻尼器(DMT—MD)。使用定义的优化目标函数,评价了双层多重调谐质量阻尼器(DMTMD)的控制性能。数值结果表明,双层多重调谐质量阻尼器(DMTMD)比多重凋谐质量阻尼器(MTMD)具有更好的有效性和对频率调谐的鲁棒性。DMTMD比双重调谐质量阻尼器(DTMD)具有更好的有效性,而DMTMD和DT—MD对频率调谐的鲁棒性近似相同。因此,双层多重调谐质量阻尼器是一种先进的结构控制策略。 相似文献
305.
本文研究了土-结构动力相互作用对采取不同控制措施的结构控制效果的影响。文中首先建立了主动调谐质量阻尼器(ATMD)、半主动磁流变阻尼器(MR)和被动多重调谐质量阻尼器(MTMD)等三种结构控制措施在时域中的控制算法和控制律,然后基于子结构法,采用间接边界元方法,通过傅里叶变换,推导了分别安装三种结构控制措施的受控结构在频域中的运动方程,数值仿真分析了某36层高层建筑的地震反应及其控制效果。结果表明,当采用ATMD或MTMD控制时,考虑土-结构动力相互作用后结构地震反应有所减小;当采用MR控制时,考虑土-结构动力相互作用后结构地震反应有很大程度的减小。由此看来,在设计软土地基上高层结构的结构控制措施时,不考虑土-结构动力相互作用对结构控制效果的影响是偏于安全的。 相似文献
306.
307.
A Combined Three-Dimensional Geological-Geostatistical-Numerical Model of Underground Excavations in Rock 总被引:1,自引:1,他引:1
Summary. This paper exploits geological and borehole geotechnical data obtained in the exploratory phase of a tunneling project to
investigate in a first place if the kriging interpolation scheme may effectively reproduce the spatial variability of rock
mass quality (Rock Mass Rating, RMR) in the vicinity of tunnels. For this purpose a quick solver in Fortran has been developed
that performs variography analysis of 3D spatial data, fast kriging estimations of RMR between borehole sampling locations
at the centroids of the elements of the numerical model, and model validation. For the purpose of an integrated underground
excavation design, a step further is made by incorporating into the 3D mechanical numerical model of the rock mass, the three-dimensional
(3D) solid geological model, thus coupling the geology with the ground (geotechnical) model (i.e. each element of the numerical
model is assigned a geological material). The mechanical properties of each finite difference cell (or Representative Elementary
Volume) of the ground model were then prescribed according to its geological type, the spatial heterogeneity of the rock mass
expressed quantitatively with the kriging model, and the upscaling calculations of the mechanical properties of the intact
rocks determined in the laboratory, based on the size-effect (strength dependence on size) and Damage Theory. Furthermore,
a preliminary numerical simulation of the advance of unsupported tunnels in the model of the heterogeneous rock mass was performed
for illustration purposes. 相似文献
308.
Wang Hongmei Ma Xiangru Liu Deng Yang Xiaofen Li Jihong 《Frontiers of Earth Science》2007,1(4):399-404
Understanding the dynamics of organic matter in modern marine water columns greatly favors the geobiological evaluation of
hydrocarbon source rocks. Biolipids could make great contribution to petroleum hydrocarbons due to their comparable chemical
components and the slightly refractory characteristics of biolipids during the microbial/thermal degradation. A variety of
environmental factors such as temperature, CO2 and salinity could affect the biochemical contents in microorganisms. As a result, microorganisms living in a changing environmental
condition might have a different contribution to the petroleum formation. Organic carbon flux is shown to bear a positive
correlation with the primary productivity only within a certain range of biomass volumes in a specific biohabitat. Furthermore,
organic matter is degraded much quickly in a water column with oxic conditions. Therefore, the anoxic condition, along with
the enhanced biological productivity, would be one of the significant factors in the formation of high-quality hydrocarbon
source rocks. The formation of biofilms and microbial mats favors the preservation of sedimentary organic matter by decreasing
the degradation rate of organic matter. Identification of biofilms and microbial mats in sedimentary rocks will thus greatly
help to understand the depositional processes of organic matter finally preserved in hydrocarbon source rocks.
__________
Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 748–754 [译自: 地球科学—中国地质大学学报 相似文献
309.
Sudhir Kumar Tewatia Pratima Rani Bose Asuri Sridharan Sunanda Rath 《Geotechnical and Geological Engineering》2007,25(2):239-255
It is shown that time compression curve obtained from one-dimensional consolidation curve in the laboratory may include six
phases. These are initial compression, first primary compression, transition from first primary compression to second primary
compression, second primary compression, and transition from second primary compression to creep and lastly creep. This paper
attempts to identify the quantitative beginnings and characteristics of these phases. A mathematical characteristic of all
the soils that follow primary consolidation as per Terzaghi’s one dimensional consolidation theory is derived. It is known
as the constant of primary consolidation. It is used to study the beginning of secondary consolidation and its effects on
primary consolidation. Another characteristic of soils for creep and total absence of primary compression is derived. Methods
are suggested for the determination of coefficients of Primary and Secondary consolidations and the compression index. 相似文献
310.
JEFF WARBURTON 《Geografiska Annaler: Series A, Physical Geography》2007,89(1):95-101
The sediment mass balance equation is the fundamental concept which underpins most sediment budget studies in cold climate environments. In these environments the interchange between water and ice plays a predominant geomorphological role. Such environments show a large variety of geomorphic processes which are conditioned by both contemporary environmental conditions but also the legacy of past events. In the northern Europe/Arctic fringe these cold regions are distributed in a fragmented fashion and are likely to be very sensitive to climate change scenarios. The significance of such changes for sediment transfer can only be established if we have good contemporary process understanding, the necessary tools to carefully monitor and model such changes, and can apply such methods at appropriate scales which integrate both sediment sources and sinks. 相似文献