共查询到20条相似文献，搜索用时 31 毫秒
1.
MoustafaElOmella C.A.Tang T.Xu 《地质与资源》2005,14(3):176-180
对浙江省花岗岩的岩相学特征及力学性质进行了研究以确定它们之间的关系.矿物学研究显示出花岗岩的交代蚀变特征,这可以反映在岩石的力学性质上.岩石材料的物理性质决定其工程学性质,在相关定量参数确定的情况下,可以预测岩石材料的工程学性质.镜下观察、硬度、密度、孔隙度及点负荷强度均可作为所研究花岗岩的定量参数.上述每个因素都可提供岩石工程学的可靠预测.岩石的物理性质受岩石成分及蚀变状态控制,而岩石的工程学性质和力学特征是其物理性质的函数. 相似文献
2.
Prediction of uniaxial compressive strength of sandstones using petrography-based models 总被引：2，自引：0，他引：2
K. Zorlu C. Gokceoglu F. Ocakoglu H.A. Nefeslioglu S. Acikalin 《Engineering Geology》2008,96(3-4):141-158
The uniaxial compressive strength of intact rock is the main parameter used in almost all engineering projects. The uniaxial compressive strength test requires high quality core samples of regular geometry. The standard cores cannot always be extracted from weak, highly fractured, thinly bedded, foliated and/or block-in-matrix rocks. For this reason, the simple prediction models become attractive for engineering geologists. Although, the sandstone is one of the most abundant rock type, a general prediction model for the uniaxial compressive strength of sandstones does not exist in the literature. The main purposes of the study are to investigate the relationships between strength and petrographical properties of sandstones, to construct a database as large as possible, to perform a logical parameter selection routine, to discuss the key petrographical parameters governing the uniaxial compressive strength of sandstones and to develop a general prediction model for the uniaxial compressive strength of sandstones. During the analyses, a total of 138 cases including uniaxial compressive strength and petrographic properties were employed. Independent variables for the multiple prediction model were selected as quartz content, packing density and concavo–convex type grain contact. Using these independent variables, two different prediction models such as multiple regression and ANN were developed. Also, a routine for the selection of the best prediction model was proposed in the study. The constructed models were checked by using various prediction performance indices. Consequently, it is possible to say that the constructed models can be used for practical purposes. 相似文献
3.
Relationship Between Petrographic Characteristics and the Engineering Properties of Jurassic Sandstones, Hamedan, Iran 总被引：2，自引：0，他引：2
M. Heidari A. A. Momeni B. Rafiei S. Khodabakhsh M. Torabi-Kaveh 《Rock Mechanics and Rock Engineering》2013,46(5):1091-1101
To study the relationship between engineering properties and petrographic characteristics, 20 rock samples were collected from Jurassic sandstones in the Hamedan region, western Iran. The specimens were tested to determine uniaxial compressive strength, point load strength index, tangent modulus, porosity, and dry and saturated unit weights. Samples were also subjected to petrographic examination, which included the observation of 11 parameters and modal analysis. Based on the results of a statistical analysis, polynomial prediction equations were developed to estimate physical and mechanical properties from petrographic characteristics. The results show that textural characteristics are more important than mineral compositions for predicting engineering characteristics. The packing density, packing proximity and grain shape are the petrographic properties that significantly affect the engineering properties of samples. Multivariate linear regression analysis was performed, employing four steps comprising various combinations of petrographic characteristics for each engineering parameter. The optimal equation, along with the relevant combination of petrographic characteristics for estimating the engineering properties of the rock samples is proposed. 相似文献
4.
The influence of the characteristics of quartz and mineral deterioration on the strength of granitic dimensional stones 总被引：2，自引：0，他引：2
Luís M. O. Sousa 《Environmental Earth Sciences》2013,69(4):1333-1346
It is important to have a thorough knowledge of the petrographic characteristics of rocks to evaluate and understand their mechanical behavior. This paper deals with the influence of the texture and the mineral characteristics of nine Portuguese granites employed as dimensional stones. This study evaluates different mineral characteristics, such as mineral deterioration, grain size, quartz fissuration and the contacts between quartz and others mineral groups. The main differences in the studied granites were identified, clarifying the relationship between the petrographic characteristics. The consequences on their respective mechanical behavior were subsequently evaluated. The physical and textural characteristics of quartz in the studied granites have proven to be very important for understanding the behavior of granitic rocks under compressive stress. Uniaxial compressive strength values are not proportional to the quartz–feldspar ratio or quartz content and there is a tendency for strength to decrease with the increase in quartz. This could be related to the increase in quartz-quartz contacts and the decrease in the rock capacity for accommodating the deformation. 相似文献
5.
The purpose of this study is to develop the empirical equations for the prediction of the physical and mechanical properties of limestone and marble from microscopic data including their mineralogical and petrographical properties and to test the validity of model equations by using multivariate statistical methods. This study was performed on 15 different rocks, composed of six limestone and nine marble samples. Stepwise multiple regression analysis was applied to predict the engineering properties of both the marble and limestone rock samples considering petrographical properties as inputs. In order to determine the overall significance of the empirical equations for prediction of the physical and mechanical properties of marble and limestone samples, the F test was also performed. As a result of this study, it is found that the empirical equations developed in this study are statistically significant. 相似文献
6.
花岗岩体是很多重要工程地基或围岩的首选。选取高放废物地质处置阿拉善预选区巴彦诺日公花岗岩样品,开展薄片鉴定,获得各花岗岩样品的矿物含量和粒径;通过单轴压缩试验,获得花岗岩的单轴抗压强度。通过对比各组样品矿物含量和粒径与单轴抗压强度,研究二者之间的关系。结果表明:对花岗岩单轴抗压强度影响最大的矿物是钾长石和黑云母,斜长石和石英的影响不明显;矿物粒径与单轴抗压强度的相关性不明显,但与某一结构岩石单轴抗压强度的相关性明显;花岗岩的强度不仅仅取决于组成矿物含量和粒径,对于其内部结构的细节（如微裂隙、矿物排列、胶结等）非常敏感。 相似文献
7.
In engineering projects such as tunnels, dams, foundations, and slope stability, the strength and elastic properties of the intact rock affect both the project design and the construction operation. It is sometimes expensive and time consuming to perform direct tests to evaluate the engineering properties (such as strength, modulus of elasticity, and Poisson's ratio) of the intact rock. The purpose of this work is to investigate the relationships between the engineering properties of the intact rock and the different types of hardness (Schmidt, shore scleroscope, abrasion, and total hardness), which are relatively cheap and easy to evaluate. In this study, dolomite, dolomitic limestone, and shale rocks were used. For simplicity, linear statistical analyses were performed. The results show that there are good relationships between the engineering properties of the intact rock and its hardness. Also, the results of this study are compared well with the results obtained by other investigators conducted on different types of rocks. 相似文献
8.
《Engineering Geology》2000,57(3-4):215-237
Weathering can induce a rapid change of rock material from initial rock-like properties to soil-like properties. The resistance of a rock to short-term weathering is described through a durability parameter called the slake durability index. As durability is an important engineering parameter, particularly for weak and clay-bearing rocks, it was assessed by a number of tests. The main purpose of this study is to assess the influence of the number of drying and wetting cycles and controls of mineralogical composition and strength on durability. For this purpose, 141 samples of different types of weak and clay-bearing rocks were selected from different parts of Turkey, and relationships between the above-mentioned rock characteristics were statistically investigated. The samples were subjected to multiple-cycle slake durability testing, X-ray diffraction (XRD) analysis and uniaxial compression testing. In addition, to assess the influence of mineralogical composition on durability, the mineral contents of the original material and the material passing from the drum of the slake durability apparatus after each cycle were also determined by XRD. The results indicate that the type and amount of clay minerals are the main factors influencing the variations of the slake durability index in all samples. The durability of the clay-bearing rocks studied correlates best with the amount of expandable clay minerals. A strong relationship between the uniaxial compressive strength and the fourth-cycle slake durability index is found only for the marls among the rock types studied. Assessment of gradation results of the spoil pile materials consisting of clay-bearing rocks also reveals that the increase in percentage of fines in old piles is indicative of material degradation, as is evident by multiple-cycle slaking. It is emphasized that two-cycle conventional slake durability testing did not appear to offer an acceptable indication of the durability of weak and clay-bearing rocks when compared with multiple-cyclic wetting and drying. Comments on the performance of the test are made that aim to make the testing process and interpretation of the results more reliable. 相似文献
9.
Engineering properties of rocks vary as they are heterogeneous materials by nature because of mineralogical composition, texture, porosity, and alteration, etc. This study focuses on the investigation of the relationship between internal structure and engineering parameters of basalt samples by digitizing the textural properties. Thin sections studies of basalts were made into three groups: aphanitic, amygdaloidal, and vesicular on the basis of texture. Further, the textural properties were digitized in thin sections and the texture coefficient (TC) of each group was calculated. Uniaxial compressive strength, dry unit weight, point load strength index, Schmidt hammer rebound, and P-wave velocity of the samples were determined in the laboratory. Simple regression analyses were performed using the laboratory results incorporating first TC and engineering parameters and the second phase of the analysis focused on the relationship between uniaxial compressive strength and the rest of the parameters of samples with different texture coefficients. The highest texture coefficient was found to be 0.50 in aphanitic basalts while vesicular basalts have the lowest TC of 0.37. As the TC increases, rock strength increases. Strong-very strong correlations between uniaxial compressive strength and the rest of the engineering parameters of aphanitic and amygdaloidal-basalts with a TC of 0.50 and 0.45 are in agreement with the findings in the literature while there are no meaningful correlations between uniaxial strength and the aforementioned parameters except dry unit weight in vesicular basalts. These results indicate that the presence of empty pores in vesicular basalts reduced the uniaxial compressive strength and TC by increasing the heterogeneity. 相似文献
10.
Textural characteristics are a major factor in determining the mechanical behaviour of rocks and in the prediction of performance of rock cutting and drilling equipment. The principal textural characteristics of rocks are grain size, grain shape, grain orientation, relative proportion of grains and matrix material which were herein quantitatively measured using a modern image analysis system. These features resulted in a texture coefficient represented by a single number for each rock specimen. In this study a range of both textural and mechanical data for a range of rock types are given with some of the textural determination methodology. Correlation between textural and physical properties are also highlighted. The results of drilling tests using polycrystalline diamond compact (pin and hybrid) and impregnated diamond core bits in the rocks are presented which demonstrate the influence of rock texture on drillability. The rock texture can be used as a predictive factor for assessing the drillability and cuttability, mechanical and wear performance of rocks. 相似文献
11.
The engineering characteristics of weathered soft rock are important contents of soft rock mechanics. They also play a significant role in compacting deformation, which has been known to exert a significant amount of influence on the stability of highway filling subgrade engineering. In an effort to investigate this aspect of the problem, compacting tests and unconfined compressive strength tests have been carried out on weathered argillaceous slate and pelitic siitstone rocks, which are broken and graded before the test. The testing results indicate that the relationships of both between stress and strain and between axial strain and tangent modulus are exponential relationships; the size of the grain plays some influence on the deformation modulus, whereas the water content impacts the compressive strength greatly, which shows quadratic function; the unconfined compressive strength is linear with the dry density of loose soft rock mixtures. Therefore, the water content must be controlled in both the design and the construction of subgrade engineering of soft rock filling, and at the same time some effective measures should be taken to reach the requirement of compaction. 相似文献
12.
变质锆石成因的岩相学研究——高级变质岩U-Pb年龄解释的基本依据 总被引：50，自引：3，他引：50
岩相学在研究高级变质岩 (含深熔片麻岩 )的锆石中起着重要的作用 ,其内容主要包括锆石的形貌和表面特征 ,锆石在岩石中的赋存状态 ,与主晶的关系和内部结构等方面。基于大别山地区的一些榴辉岩相岩石、麻粒岩相岩石和片麻状花岗质岩石中锆石的研究 ,阐述了继承锆石、变质锆石、深熔锆石、变质增生、深熔增生和后期流体改造的基本岩相学特征。结合大别山地区的 4个实例 ,说明了高级变质岩中锆石的岩相学研究方法和步骤 ,并初步提出了高级变质岩锆石U -Pb年龄解释的岩相学标志。 相似文献
13.
The rocks within the Singhbhum shear zone in the North Singhbhum fold belt, eastern India, form a tectonic melange comprising
granitic mylonite, quartz-mica phyllonite, quartz-tourmaline rock and deformed volcanic and volcaniclastic rocks. The granitic
rocks show a textural gradation from the least-deformed variety having coarse-to medium-grained granitoid texture through
augen-bearing protomylonite and mylonite to ultramylonite. Both type I and type II S-C mylonites are present. The most intensely
deformed varieties include ultramylonite. The phyllosilicate-bearing supracrustal rocks are converted to phyllonites. The
different minerals exhibit a variety of crystal plastic deformation features. Generation of successive sets of mylonitic foliation,
folding of the earlier sets and their truncation by the later ones results from the progressive shearing movement. The shear
sense indicators suggest a thrust-type deformation. The microstructural and textural evolution of the rocks took place in
an environment of relatively low temperature, dislocation creep accompanied by dynamic recovery and dynamic recrystallization
being the principal deformation mechanisms. Palaeostress estimation suggests a flow stress within the range of 50–190 MPa
during mylonitization. 相似文献
14.
We examine a large strike-slip fault zone that juxtaposes low-grade clastic metasedimentary rocks with coarse-grained granite near the brittle-ductile transition. The load-bearing matrixes in granite-derived ultramylonites and pelite and wacke metasedimentary intervals are texturally similar, and all deformed by diffusion-assisted granular flow. Granite underwent rapid strengthening as the pluton cooled followed by rapid weakening driven by brittle grain-size reduction and mixing that catalyzed ultramylonite formation. The textural and mineralogical similarity of pelitic intervals across the zone indicates they experienced little textural and reaction weakening. Wacke intervals record progressive textural and reaction weakening in an open system. Quartz recrystallized grain sizes in granite-derived ultramylonites record ∼2-times more differential stress than those in metasedimentary rocks in the interior of the zone. The relative weakness of metasedimentary rocks is correlated with fluid influx that likely enhanced diffusion and grain-boundary sliding in pelitic and wacke intervals and catalyzed textural and reaction weakening in wacke intervals. The lack of evidence for fluid and ionic communication with granitic rocks indicates that fluid movement was restricted to foliation-parallel pathways within single rock units. This localized fluid influx is the best explanation for the strength contrasts between texturally similar fault rocks deformed by similar mechanisms. 相似文献
15.
Salt weathering in dual-porosity building dolostones 总被引：2，自引：0，他引：2
D. Benavente J. Martínez-Martínez N. Cueto M.A. García-del-Cura 《Engineering Geology》2007,94(3-4):215-226
The influence of rock fabric on physical weathering due to the salt crystallization of selected brecciated dolostones is discussed. These dual-porosity dolostones are representative of heterogeneous and anisotropic building rocks, and present highly complex and heterogeneous rock fabric features. The pore structure of the matrix and clasts is described in terms of porosity and pore size distribution, whereas the relative strength for each textural component is assessed using the Knoop hardness test. The whole characterisation process was carried out using the same samples as those used in the standard salt durability test (EN-12370), including connected porosity, the water saturation coefficient, fissure density, compressional wave velocity and waveform energy.
Results show the most important rock fabric elements to be considered are the matrix and clast properties and the nature of fissures. Firstly, a relatively weak matrix was the focus of major granular disintegration as it presents high porosity, low pore radius and reduced strength. Secondly, narrow micro-fissures appear to be important in the decay process due to the effectiveness of crystallization pressure generated by salt growth. On the contrary, macro-fissures do not contribute greatly to rock decay since they act as sinks to consume the high supersaturations caused by growth of large crystals. Additionally, an analysis of stress generated by crystallization was carried out based on the general situation of a lenticular crystal geometry. Finally, the relationships between whole petrophysical properties and durability were established using a principal component analysis. This analysis has clearly established that the durability of rocks affected by salt crystallization mechanisms diminishes in weaker and anisotropic rocks with high porosity and fissure density. 相似文献
16.
17.
The relationship between uniaxial compressive strength and degradation was investigated for selected rock types, by using regression analyses to determine whether degradation was a useful predictor of compressive strength. In addition, the effects of aggregate particle size, number of hammer blows during the degradation test, engineering index properties, petrographic characteristics, and water saturation on the compressive strength-degradation relationship were evaluated. The results show that strong inverse relationships exist between compressive strength and degradation (measured on a 9.5-4.75-mm size aggregate) for sandstones and igneous/metamorphic rocks, but that no significant relationship exists for limestones/dolomites. The results also indicate a strong positive correlation between degradation and L.A. abrasion loss and can be used to establish a limit of allowable degradation for practical applications. Engineering index properties do not significantly affect the relationship between compressive strength and degradation but petrographic characteristics are important in explaining the strength and degradation behavior of the rocks studied. Water saturation decreases compressive strength and increases degradation to varying degrees. 相似文献
18.
The provenance of Eocene–Oligocene turbidites from the Pindos Foreland Basin, SW Greece, has been constrained using petrographical and geochemical techniques. Modal petrographic analysis of the studied sandstones shows that the source area comprises sedimentary, metamorphic, and plutonic igneous rocks deposited in a recycled orogenic environment and in magmatic arc province. The relative proportions of the detrital components indicate that the Late Eocene–Early Oligocene sandstones of West Peloponnesus are quartz-rich and were primarily derived from granitic and metamorphic basement rocks typically of a tectonically active area. Major, trace, and rare earth element (REE) concentrations in both sandstones and mudstones complement the petrographical data indicating an active continental margin/continental island arc signature. All the samples are light REE, enriched relative to heavy REE (HREE), with flat HREE pattern and positive Eu anomalies, suggesting that the processes of intra-crustal differentiation (involving plagioclase fractionation) were not of great importance. The results derived from the multi-element diagrams also suggest an active margin character and a mafic/ultramafic source rock composition. 相似文献
19.
M. Risnen 《Engineering Geology》2004,74(3-4):197-211
The relationships between petrographical and mechanical properties of rock aggregate raw materials from the hybridised, subvolcanic Jaala–Iitti complex, southeastern Finland, were investigated. Petrography was quantified from polished thin sections with a polarising microscope to determine the modal composition and grain size distribution, and resistance to fragmentation and abrasion were determined. Abundance of fine-grained minerals (especially of hornblende), fine grain size-dominated grain size distribution, uniform spatial dispersion of hornblende crystals, and intense micrographic intergrowth texture with interlocking grain boundaries were found to have the greatest positive influence on the mechanical properties. The results showed the potentiality of hybridised rocks as raw materials for high quality aggregates that can resist fragmentation and abrasion. 相似文献