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1.
Quality assessment of replacement stones for the Cologne Cathedral: mineralogical and petrophysical requirements 总被引：2，自引：2，他引：0
Owing to its long building history, different types of building stones comprised the construction of the Cologne Cathedral. Severe damage is observed on the different stones, e.g., sandstones, carbonate, and volcanic rocks, especially when the different stone materials neighbor the medieval “Drachenfels trachyte” from the “Siebengebirge”. The question arises, “Is the insufficient compatibility of the implemented building materials causatively related to the strong decay of the Drachenfels trachyte?” The present investigations focus on the petrography and mineralogical composition of eight different stones from the Cologne Cathedral. Petrophysical data, i.e., phase content, moisture and thermal characteristics as well as strength properties are determined and discussed in correlation to each other, showing that not only in terms of lithology great differences exist, but also the petrophysical properties strongly diverge. The ascertained parameters are discussed in view of the deterioration behavior and decay mechanisms of the different stones. To evaluate the compatibility of original, replacement and modern building materials, the properties of the investigated stones are compared to those of Drachenfels trachyte by means of constraints given in the literature. Besides optical properties, petrophysical criteria are also defined as well as strength values. It could be shown that primarily moisture properties, i.e., capillary and sorptive water uptake, water saturation, drying processes and moisture dilatation can be addressed to the deterioration processes. 相似文献
2.
Most studies dealing with material properties of sandstones are based on a small data set. The present study utilizes petrographical and petrophysical data from 22 selected sandstones and ~300 sandstones from the literature to estimate/predict the material and weathering behaviour of characteristic sandstones. Composition and fabric properties were determined from detailed thin section analyses. Statistical methods applied consist of data distributions with whisker plots and linear regression with confidence regions for the petrophysical and weathering properties. To identify similarities between individual sandstones and to define groups of specific sandstone types, principal component and cluster analyses were applied. The results confirm an interaction between the composition, depositional environment, stratigraphic association and diagenesis, which leads to a particular material behaviour of sandstones. Three different types of pore radii distributions are observed, whereby each is derived from different pore space modifications during diagenesis and is associated with specific sandstone types: (1) bimodal with a maximum in capillary and micropores, (2) unimodal unequal with a maximum in smaller capillary pores and (3) unimodal equable with a maximum in larger capillary pores. Each distribution shows specific dependencies to water absorption, salt loading and hygric dilatation. The strength–porosity relationship shows dependence on the content of unstable lithic fragments, grain contact and type of pore radii distribution, cementation and degree of alteration. Sandstones showing a maximum of capillary pores and micropores (bimodal) exhibit a distinct hygric dilatation and low salt resistance. These sandstones are highly immature sublitharenites–litharenites, characterized by altered unstable rock fragments, which show pointed-elongated grain contacts, and some pseudomatrix. Quartz arenites and sublitharenites–litharenites which are strongly compacted and cemented, show unimodal unequal pore radii distributions, low porosity, high strength and a high salt resistance. The presence of swellable clay minerals in sublitharenites–litharenites leads to a medium to high hygric dilatation, whereas quartz arenites show little hygric dilatation. Sandstones with unimodal equal pore radii distribution mostly belong to weakly compacted and cemented mature quartz arenites. These are characterized by high water absorption and high porosity, low to medium strength and a low salt resistance. The data compiled in this study are used to create a sandstone quality catalogue. Since material properties are dependent on many different parameters of influence, the transition between different lithotypes is fluent. 相似文献
3.
Joerg Ruedrich Tobias Bartelsen Reiner Dohrmann Siegfried Siegesmund 《Environmental Earth Sciences》2011,63(7-8):1545-1564
The expansion processes that develop in building stones upon changes of moisture content may be an important contributing factor for their deteriorations. Until recently, few data could be found in the literature concerning this parameter and weathering processes. Moreover, the processes that may be responsible for the moisture related expansion of natural building stones are not yet completely understood. To further elucidate this process, extensive mineralogical, petrophysical and fabric investigations were performed on eight German sandstones in order to obtain more information regarding the weathering process and its dependence on the rock fabric. The analysed sandstones show a wide range of pore size distributions and porosities. A positive correlation with the fabric and the pore space can be found for all studied petrophysical parameters. The intensity of the expansion and related swelling pressure cannot be attributed only to the swelling of clay minerals. The investigations suggest that the micropores and the resulting disjoining pressure during wet/dry cycles also play an important role. The results obtained suggest that the mechanism is related to the presence of liquid water within the porous material. 相似文献
4.
The investigated rock material belongs to the group of upper cretaceous quader sandstones which are very important construction stones in Poland and Germany. The mineral composition of the rocks is relatively uniform??they are quartzose sandstones. The most important feature is their good workability and comparatively high weathering resistance. Still, regardless of the apparent resemblance, the observations carried on buildings and monuments show differences in weathering processes. The undertaken test was an attempt to verify the proposed before rock classification, performed on the basis of parameterization of porosimetric cumulative intrusion volume curves. The aim of the experiment was the evaluation of the sandstone petrography (including the structure, texture and porosity of the rock) influence on the weathering process. The modelling of accelerated weathering was conducted in Chamber for Ageing Acceleration, where some weather circumstances were simulated (insolation, rain and frost). As the result of the weathering experiment it could be stated that the dominant mechanism of the sandstones deterioration was granular disintegration and weight loss as a consequence of sample destruction. The most important factor influencing rock deterioration is rock texture, especially the character of grain contacts. The effective porosity is a requisite of potential for the stone to take in and hold water, and hence of resistance to weathering. In case of silica-cemented sandstones, the deciding criterion influencing weathering resistance is pore structure. In case of sandstones with clay cement, the most important is mineral composition of the rock. 相似文献
5.
6.
<正>The western Sichuan Basin,which is located at the front of the Longmen Mountains in the west of Sichuan Province,China,is a foreland basin formed in the Late Triassic.The Upper Triassic Xujiahe Formation is a tight gas sandstone reservoir with low porosity and ultra-low permeability, whose gas accumulation and production are controlled by well-developed fracture zones.There are mainly three types of fractures developed in the Upper Triassic tight gas sandstones,namely tectonic fractures,diagenetic fractures and overpressure-related fractures,of which high-angle tectonic fractures are the most important.The tectonic fractures can be classified into four sets,i.e.,N-S-,NE-, E-W- and NW-striking fractures.In addition,there are a number of approximately horizontal shear fractures in some of the medium-grained sandstones and grit stones nearby the thrusts or slip layers. Tectonic fractures were mainly formed at the end of the Triassic,the end of the Cretaceous and the end of the Neogene-Early Pleistocene.The development degree of tectonic fractures was controlled by lithology,thickness,structure,stress and fluid pressure.Overpressure makes not only the rock shear strength decrease,but also the stress state change from compression to tension.Thus,tensional fractures can be formed in fold-thrust belts.Tectonic fractures are mainly developed along the NE- and N-S-striking structural belts,and are the important storage space and the principal flow channels in the tight gas sandstone.The porosity of fractures here is 28.4%of the gross reservoir porosity,and the permeability of fractures being two or three grades higher than that of the matrix pores.Four sets of high-angle tectonic fractures and horizontal shear fractures formed a good network system and controlled the distribution and production of gas in the tight sandstones. 相似文献
7.
基于高压压汞和核磁共振测试方法,结合分形理论对鄂尔多斯盆地延长组致密砂岩孔喉结构与油藏物性进行了表征。采用毛管束模型和润湿相模型计算了高压压汞孔喉分形维数,利用核磁共振测试T2谱分别计算了大孔、中孔、小孔以及总孔隙的分形维数;对各分形维数与油藏物性之间的关系进行了对比分析。研究表明：基于高压压汞曲线计算岩心分形维数时,相比于润湿相模型,毛管束模型计算得到的分形维数与油藏物性之间具有更好的相关性,随着分形维数增加,平均半径减小,孔喉结构非均质性增强,油藏物性变差。核磁总孔隙分形维数与油藏物性相关性较差,大孔和中孔的分形维数与油藏物性具有较好的相关性,其中随着大孔和中孔分形维数增加,岩心渗透率降低,油藏物性变差;与小孔相比,大孔和中孔的分形维数与油藏物性的相关性更强,表明致密砂岩储层物性主要受大孔和中孔控制,分形维数可以有效表征致密砂岩小孔、中孔和大孔对油藏物性的影响。 相似文献
8.
针对红山窑膨胀红砂岩具有微膨胀、易软化、易风化的特点,采用扫描电子显微镜、X射线衍射仪、MTS815.03岩石力学刚性电液伺服试验机等先进的设备为测试手段,对3种不同风化程度的膨胀红砂岩湿化过程进行观察和机理分析,从试验和机理两方面探讨膨胀红砂岩的湿化性,从而进一步阐明红砂岩膨胀性、裂隙化具有本质的区别。试验结果表明：(1) 中风化红砂岩干燥时抗压强度为5.85 MPa,饱和试样为0.20 MPa,岩石本身强度随吸水率增加而明显下降,具有强烈的软化作用;(2) 膨胀红砂岩的湿化性随胶结系数的减小而愈加强烈,与红砂岩风化程度(埋深)无关。这些研究成果对红山窑水利枢纽工程红砂岩地基开挖易裂以及边坡表层溜坍预治具有较大的指导意义。 相似文献
9.
出露于羌塘盆地沃若山地区的雀莫错组砂岩是北羌塘盆地早侏罗世的沉积物,对研究早侏罗世沉积盆地的演化特征具有重要的意义。通过对其地球化学特征的分析研究,结果表明该组砂岩为被动大陆边缘裂陷期的沉积产物,岩性主要为岩屑砂岩,岩石矿物成分主要在钾长石、斜长石、伊利石、绿泥石以及石英之间变化。化学风化作用指标(CIW)、化学蚀变作用指标(CIA)和A-CN-K图解,反映该组砂岩的碎屑成分受到了强烈的风化环境,并在风化过程中发生钾交代作用,长石发生伊利石化。化学组分指标(ICV)表明岩石碎屑为近源的第一次旋回沉积物,受沉积分选和再循环作用影响不大;A-CN-K图解还反映出砂岩碎屑源岩中斜长石含量高于钾长石含量,主要在花岗岩和花岗闪长岩之间变化;稀土元素特征表明该组砂岩具有同源性,其成分主要受源区岩石成分控制,为酸性火山岩类。 相似文献
10.
Cavernous weathering is commonly found on sandstone slopes in different environments. Either a single dominant process or polygenetic agents require to be invoked in order to interpret the development. The Yongningshan hill of the central Loess Plateau is representative of cliff dwellings in Northwest China, which is characterized by well-developed cavernous weathering features and provides a good opportunity for the better understanding of sandstone weathering in the Loess Plateau. Multiple methods, including field survey, in-situ rock strength measurement, along with experiments on samples for microscopic observation, element composition and salt chemistry, were employed to investigate the controlling factors of cavernous weathering. The results show that cavern development is different on the four slopes with the western slope hosting massive honeycombs, tafoni and hardened surfaces. The porous and permeable aeolian sandstones are fundamental, because they provide space and pathways for the transportation of water and salt, honeycombs dominantly aligning within the lamination of cross-beds. The environmental factors such as the seasonal wetting and drying cycle, aeolian salt, moisture and water vapor are key factors for the development of cavernous weathering forms. The northern and northwestern wind-blown dust storms have brought abundant salts, the lengthier dry periods of the wetting and drying cycle being beneficial for salt accumulation within caverns, favoring salt weathering. 相似文献
11.
Egypt is characterized by wide occurrence of serpentinites, particularly in the central and southern parts of Eastern Desert. There are several cooperate factors that affect the serpentinites used as ornamental stones. These factors involve mineralogical characteristics （including mineral composition and microstructure parameter）, physical properties and mechanical properties. Antigorite is an essential serpentinite mineral, with a minor amount of chrysotile. Talc, carbonates （magnesite and dolomite） and tremolite are the main associated minerals. Quality and quantity of associated minerals such as talc and carbonates （dolomite and magnesite） affect the properties of serpentinites used as ornamental stones. Carbonates are resistant to weathering but suffer from acidic cleaning agents in interior use, whereas serpentinites with a high content of talc used on external faces undergo an increase in volume and a consequent rapid degradation. Studied serpentinites are characterized by relatively small grain size with foliated texture, low water absorption, low porosity, and high abrasion resistance. In the samples studied the uniaxial compressive strength （UCS） varies between 89 and 189 MPa, with an average of 152 MPa. According to the classification of Bell （1992）, sample No. B8 is very high in strength while the rest high in strength. 相似文献
12.
Zur Diagenese fluviatiler Sandsteine 总被引：1，自引：0，他引：1
Prof. Dr. Hans Füchtbauer 《International Journal of Earth Sciences》1974,63(3):904-925
Are cement minerals that form during the first stages of diagenesis indicative of the environment of deposition? Discussions of fluvial, marine, and evaporitic sandstones of Triassic and Upper Carboniferous age (fig. 1) indicate that kaolinite, sudoite, and potassium feldspar cements can be regarded as characteristic of freshwater sandstones, whereas (early) chlorite, analcime and albite cements are found in marine and evaporitic sandstones mainly, provided that influences of meteoric water during diagenesis can be excluded. Humid climate favors kaolinite, arid favors potassium feldspar. Early diagenetic siderite concretions develop in coal swamps. Reddish biotites are not resistant during synsedimentary weathering in humid alluvial plains. As a consequence of increasing pH, temperature, and salinity of the interstitial fluids with increasing burial depth, common sequences of cementation include (1) silicates + quartz, (2) carbonates, (3) sulphates, (4) halite (fig. 3). The formation of quartz — the most important cement — is mainly governed by modifications of the micro-environment (e.g. pressure solution). In the Lower Triassic Buntsandstein, lithification due to quartz cementation occurred at a burial depth of about 1000–1200 m in alluvial as well as in brackisch to marine sandstones. Cementation by potassium feldspar (in the alluvial sandstones) and by analcime transforming into albite (in the brackish to evaporitic sandstones) occurred earlier. This was shown by investigations of minus-cement-porosity and contact strength (fig. 2). 相似文献
13.
Wanja Wedekind Christian J. Gross Andreas Hoffmann Siegfried Siegesmund 《Environmental Earth Sciences》2018,77(21):735
Sandstones, clay in the form of bricks and laterite are the building materials used by the Khmer to construct the imposing and magnificent temples in Southeast Asia. Many of these monuments suffer from fracturing, sanding, contour scaling, crust formation and salt weathering. The affinity to weathering is closely connected to the type of material. Two sandstone types classified as feldspathic arenite and quartz arenite of Angkor as well as two arkosic sandstones from Thailand are described and investigated in this study. Important petrophysical properties determined for the different sandstones consist of hydric expansion, thermal expansion, pore radii distribution and ultrasonic velocity. Different investigations such as capillary water uptake, surface hardness, hygroscopic water sorption, and salt resistance tests were undertaken in the laboratory to characterize the various rock types. Observations and quantified damage mapping were done onsite at the Phnom Bakheng Temple. Contour scaling in the form of weathering crusts is one of the main deterioration features observable at the Angkor monuments. Comparisons are made between the building stone, the crust material from the Phnom Bakheng Temple and fresh stone material used for restoration. Significant differences in hydric and especially in thermal expansion of the crust and sandstone have been determined. The results seem to indicate that extensional processes occur, which can be considered a force for detachment (i.e., contour scaling, flaking). In an experimental trial, the hydric and thermal expansion of the weathering crust and the building stone was significantly reduced by using a weak acid for the crust and a swelling inhibitor for the original building stone. 相似文献
14.
The Yidun Group extends from the Shangri-La region to the south and the Changtai region to the north,and is an important component of the Triassic Yidun arc in the eastern Tibetan plateau.It is composed of the Lieyi,Qugasi,Tumugou and Lanashan Formations from the base upward.Both the Lieyi and Lanashan Formations consist dominantly of black or gray slate and sandstone,whereas the Qugasi and Tumugou Formations have variable amounts of mafic to felsic volcanic rocks and turfs accompanied with gray slate and sandstone.Sandstone from the Yidun Group has variable CIA values from 55 to 76,indicative of mild to moderate weathering condition for the source rocks.All the sandstones define a general weathering trend nearly parallel to the A-CN boundary in the A-CN-K triangular diagram,implying limited effect of diagenetic and post-depositional K-metasomatism.Dominant detrital quartz and feldspar grains of the sandstones suggest predominantly felsic sources.Relatively high Y/Ni and low Cr/V ratios of sandstones from the Yidun Group indicate more contribution from felsic than mafic sources.Similarly,the Yidun sandstones have Co/Th and La/Sc ratios generally similar to upper continental crust （UCC） and cluster between UCC and felsic sources,indicating felsic rocks as primary sources.Granodiorite represents the average chemical composition of sources as evaluated by extending the predicted weathering trend back to the feldspar join in A-CN-K diagram.Prominently high Zr/Sc ratio or Hf concentration and Paleoproterozoic Nd modal ages （1.94-2.21 Ga）point to input of recycling components derived from old sedimentary source in a relatively stable tectonic setting. 相似文献
15.
冷生风化作用对边坡稳定性影响 总被引：1，自引：0，他引：1
The experiment shows that considerable influence on density rock properties are subjected by nival weathering conditions. The main parameter defining the rock suitability for solution various engineering and geological problems is its firmness limit on single axis pressing. The firmness properties of sandstone being in absolutely dry condition for Kabakta suite at the beginning of investigation was 64.7 MPa, for Nerungri suite sandstones it was 48. 7 MPa. The investigations showed how much the nival conditions of cryohypergenesis of rock sandstones in Kabakta and Nerungri suites have destructive influence in comparison with aquale and more over aerale conditions. In the aerale conditions sedimentary rock firmness of Kabakta suite decreased to 23.2 MPa, in aquale conditions to 16.5, and in the nivale conditions to 8.9 MPa. In Nerungri suite sandstones are according to 17.7 MPa, 11.1 MPa, and 6 MPa after 300 freezing and thawing cycles. The common sandstone firmness decrease of Kabakta suite was 25 %,of Nerungri suite it was 23.8%. Marlstone samples after 400 FTC decrease to 62% in the nivale conditions and to 33 % in the aerale conditions. After 3～5 years of exploitation marlstone will destruct due to structural and textural inhomogenesis up to gruss, i.e. it will not meet the requirements of durability.Judging by the results of carried out experiment it should be concluded that by cryogenic weathering the sedimentary rocks (sandstones) and rocks with schistose lithogenic texture (marlstone) are subjected to disintegration. The primary rock samples firmness considerably influences on the disintegration rate. 相似文献
16.
A key challenge in the oil and gas industry is the ability to predict key petrophysical properties such as porosity and permeability. The predictability of such properties is often complicated by the complex nature of geologic materials. This study is aimed at developing models that can estimate permeability in different reservoir sandstone facies types. This has been achieved by integrating geological characterization, regression models and artificial neural network models with porosity as the input data and permeability as the output. The models have been developed, validated and tested using samples from three wells and their predictive accuracy tested by using them to predict the permeability in a fourth well which was excluded from the model development. The results indicate that developing the models on a facies basis provides a better predictive capability and simpler models compared to developing a single model for all the facies combined. The model for the combined facies predicted permeability with a correlation coefficient of 0.41 which is significantly lower than the correlation coefficient of 0.97, 0.93, 0.99, 0.96, 0.96 and 0.85 for the massive coarse-grained sandstones, massive fine-grained sandstones-moderately sorted, massive fine-grained sandstones-poorly sorted, massive very fine-grained sandstones, parallel-laminated sandstones and bioturbated sandstones, respectively. The models proposed in this paper can predict permeability at up to 99% accuracy. The lower correlation coefficient of the bioturbated sandstone facies compared to other facies is attributed to the complex and variable nature of bioturbation activities which controls the petrophysical properties of highly bioturbated rocks. 相似文献
17.
云冈石窟砂岩特性与岩石风化试验 总被引：1，自引：0，他引：1
侏罗纪期间河相沉积而成的巨大砂岩透镜体是云冈石窟遗产载体,在目前环境条件下,石窟砂岩风化破坏非常严重。通过现场调查表明,在不同细分层位,砂岩破坏特征与其沉积环境及沉积构造密切相关。进一步对不同风化程度样品进行测试,以此建立起风化评估依据,结果表明,该砂岩化学风化主要体现在胶结物流失、长石蚀变,而次生可溶盐结晶及冻融形成的物理破坏也不应该忽视。通过风化模拟试验可知：酸的溶蚀对石窟岩体表面造成直接破坏;同时,形成的可溶盐将导致砂岩出现由内而外劣化现象;由于岩石的孔隙率低、渗透性较差且胶结密实,岩石抵抗冻融作用相对较强。建议云冈石窟目前保护措施以治水为主,通过减少崖壁表面渗水、洞窟裂隙渗水及底部泥岩泛潮来减少上述劣化作用效应。 相似文献
18.
《Sedimentology》2018,65(4):1277-1300
Fluvially derived tuffaceous Chinle sandstones from Petrified Forest National Park provide a well‐preserved Late Triassic archive of climate information. Petrographic analysis of 38 Chinle sandstones provides new insight into the depositional history and evolution of palaeoclimate during Chinle deposition. This study focuses on the relationship between climate and meteoric diagenesis as a guide for constraining climate change in western equatorial Pangea during the Late Triassic. Petrographic analysis of Chinle sandstones reveals their wide range of textural attributes, as well as pedogenic and shallow burial diagenetic features that occurred during the Late Triassic. These diverse petrological characteristics are indicative of the evolving Late Triassic climate, when placed into a well‐constrained stratigraphic and geochronological framework. The stratigraphic succession is characterized by variations in the abundance of framework grains, detrital matrix, weathering intensity of feldspar and volcanic rock fragments, and the mineralogy of clay cements. Climate records from Chinle palaeosol geochemistry indicate a progression from wet to dry conditions. This trend is also reflected in the meteoric diagenetic features of Chinle sandstones. During deposition of the lower Chinle, elevated rainfall promoted the weathering of labile volcanic detritus to kaolinite, whereas feldspars (especially plagioclase) were partially or completely dissolved. In the upper Chinle, a trend towards drier conditions favoured the formation of smectite and less feldspar dissolution resulting in a higher abundance of well‐preserved plagioclase grains. Shallow burial meteoric weathering reactions in Chinle sandstones reflect the evolving climate during the Late Triassic. 相似文献
19.
Herwig Marbler Kirsten P. Erickson Michael Schmidt Christof Lempp Herbert Pöllmann 《Environmental Earth Sciences》2013,69(6):1981-1998
The geochemical and geomechanical behaviour of reservoir rocks from deep saline aquifers during the injection and geological storage of CO2 is studied in laboratory experiments. A combination of geochemical and geomechanical studies was carried out on various sandstones from the North German Basin. After the mineralogical, geochemical and petrophysical characterization, a set of sandstone samples was exposed to supercritical (sc)CO2 and brine for 2–4 weeks in an autoclave system. One sample was mineralogically and geochemically characterised and then loaded in a triaxial cell under in situ pressure and temperature conditions to study the changes of the geomechanical rock properties. After treatment in the autoclaves, geochemical alterations mainly in the carbonate, but also in the sheet silicate cements as well as in single minerals of the sandstones were observed, affecting the rocks granular structure. In addition to partial solution effects during the geochemical experiments, small grains of secondary carbonate and other mineral precipitations were observed within the pore space of the treated sandstones. Results of additional geomechanical experiments with untreated samples show that the rock strength is influenced by the saturation degree, the confining pressure, the pore fluid pressure and temperature. The exposure to pure scCO2 in the autoclave system induces reduced strength parameters, modified elastic deformation behaviour and changes of the effective porosity in comparison to untreated sandstone samples. Experimental results show that the volume of pore fluid fluxing into the pore space of the sandstones clearly depends on the saturation level of the sample. 相似文献
20.
针对坪北油田勘探开发特点及其所出现的问题，笔者运用多层次基准面旋回和可容空间变化原理，通过分析由基准面变化导致的沉积地层记录和层序界面类型、规模及地层的堆叠样式的差异，在对长4 5—长6油组基准面旋回层序精细划分和等时对比的基础上，讨论等时地层格架内砂体时空演化规律，并探讨了基准面变化与储层物性的关系。 相似文献