Durability Of Rocks Research Articles

Cyclic migration of weak earthquakes between Lunigiana earthquake of October 10, 1995 and Reggio Emilia earthquake of October 15, 1996 (Northern Italy)

The cyclic migration of weak earthquakes (M ≥ 2.2) which occurred during the yearprior to the October 15, 1996 (M = 4.9) Reggio Emilia earthquake isdiscussed in this paper. The onset of this migration was associated with theoccurrence of the October 10, 1995 (M = 4.8) Lunigiana earthquakeabout 90 km southwest from the epicenter of the Reggio Emiliaearthquake. At least three series of earthquakes migrating from theepicentral area of the Lunigiana earthquake in the northeast direction wereobserved. The migration of earthquakes of the first series terminated at adistance of about 30 km from the epicenter of the Reggio Emiliaearthquake. The earthquake migration of the other two series halted atabout 10 km from the Reggio Emilia epicenter. The average rate ofearthquake migration was about 200–300 km/year, while the time ofrecurrence of the observed cycles varied from 68 to 178 days. Weakearthquakes migrated along the transversal fault zones and sometimesjumped from one fault to another. A correlation between the migratingearthquakes and tidal variations is analysed. We discuss the hypothesis thatthe analyzed area is in a state of stress approaching the limit of thelong-term durability of crustal rocks and that the observed cyclic migrationis a result of a combination of a more or less regular evolution of tectonicand tidal variations.

Factors affecting the durability of selected weak and clay-bearing rocks from Turkey, with particular emphasis on the influence of the number of drying and wetting cycles

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.

Weathering of coastal defensive structures in southwest England: a 500 year stone durability trial

Historic structures can be viewed as exposure trials of the stone of which they are constructed. As such, they represent a geomorphological weathering experiment. Several structures of Henrician (sixteenth century) and greater age on the coast of southwest England have been exposed to coastal salt weathering for 500–600 years. Long-term weathering rates on five different rock groups are derived from careful study of weathering depths and forms. There is significant variation in weathering rate between five major rock groups. Rank ordering of weathering rate values reveals a durability order of these rock groups, which is confirmed by local juxtapositions. Controls on rock durability in the coastal weathering environment include both mechanical and mineralogical characteristics. Specific density, and combined quartz and muscovite content, are positively related to durability; high feldspar and chlorite content are associated with low durability. Copyright © 2000 John Wiley & Sons, Ltd.

Slake durability vs ultrasonic treatment for rock durability determinations

Slake durability vs ultrasonic treatment for rock durability determinations

Effects of direct and indirect heating on the validity of rock weathering simulation studies and durability tests

Rock surface and subsurface temperature responses in samples exposed to direct heating (insolation) under natural hot desert conditions reveal considerable variability between lithologies related to differences in thermal properties, especially albedo and thermal conductivity. However, when the same samples are heated indirectly by air in an oven-based environmental cabinet, lithological differences in temperature response disappear and all samples attain temperatures similar to the air temperature within the cabinet. Rates and patterns of rock decay produced in such environmental cabinets may not, therefore, reflect those encountered under natural conditions, where breakdown is related to micro-environmental conditions at the rock/air interface and where rock temperature is one of the most important controlling factors. In addition to implications for assessment of weathering effectiveness, use of only indirect forms of heating affects the determination of comparative rock durability because all rock types are cycled through the same temperature regimes. Because temperature exerts such a major control on rock breakdown through its control on physical and chemical weathering processes, all significant factors influencing it must be included in the design of weathering simulations and durability tests.

Engineering geological properties and durability assessment of the Cappadocian tuff

Some of the unique landforms, the so-called “fairy chimneys”, which were formed within the Cappadocian tuff of central Turkey, were used as dwellings in the past and contain culturally valuable wall paintings. However, these structures are undergoing chemical and physical deterioration due to atmospheric effects. For conservation studies, an understanding of the engineering geological properties of the tuff is essential. In this study, emphasis is placed on both material and mass properties of the tuff. These properties are evaluated for the assessment of rock durability. This study shows that the Cappadocian tuff is almost fresh, with local discoloration, is moderately weak to very weak, and has low unit weight, very high porosity, and high deformability. Discontinuity surveys revealed two dominant joint sets, which not only controlled the formation but also control the structural stability of the fairy chimneys. Various methods used for the durability assessment of the Cappadocian tuff indicate poor to very poor durability. Due consideration must be given to strength reduction due to moisture, poor to very poor durability, and the adverse effects of joints on the structural stability of the fairy chimneys.

The role of clay minerals in durability of rocks: observations on basaltic rocks

The role of clay minerals in durability of rocks: observations on basaltic rocks

The role of clay minerals in durability of rocks observations on basaltic rocks

Knowledge of the durability of rocks, regardless of their size or shape, is essential for determining the safety and lifetime of structures and monuments. Hydraulic structures in particular require a high probability of survival of at least 100 years and monuments closer to a millennium. The degradation of a rock is often caused by clay minerals which are present in the rock from its origin and/or which have been formed in the rock in its geological history on account of the less stable rock constituents. In their fresh state during quarrying and mining it is difficult to recognize tendencies toward degradation and decay in rocks with time. For the selection of high quality construction materials (basaltic rocks) a series of new testing techniques has been developed in which the focus is on the role of clay minerals. This paper deals with occurrences, neoformation and behaviour of clay minerals which contribute to an early recognition of tendencies of rock decay.

Assessment of rock durability through index properties : Rodrigues, J D; Jeremias, F T Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6–10 August 1990V4, P3055–3060. Publ Rotterdam: A A Balkema, 1990

Assessment of rock durability through index properties : Rodrigues, J D; Jeremias, F T Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6–10 August 1990V4, P3055–3060. Publ Rotterdam: A A Balkema, 1990

The geology of the Lesotho Highlands Water Project with special reference to the durability of construction materials

The Lesotho Highlands Water Project is situated in the Kingdom of Lesotho and the adjoining north-easthern part of the Orange Free State Province of the RSA in an areaunderlain by Triassic and Jurassic basalts of the Lesotho Formation and Triassic sandstones and mudrocks of the Karoo Sequence. The Project will consist of a series of dams and tunnels to convey water from the Lesotho Highlands to the industrial centre of the Republic of South Africa. The geological setting of the project area and some engineering geological properties of the underlying stratigraphic horizons is discussed. The geotechnical properties of the different rock types are discussed with special reference to their use as concrete aggregate. The durability of basalt is primarily determined by the amount of secondary smectite clays present in the rock. These clays occur as discrete grains or as intergrowths with other secondary minerals disseminated throughout the rock. The clays originate from the deuteric alteration of primary glass, pyroxene, olivine and rarely plagioclase and also occur as infillings of amygdales. The durability of the sedimentary rocks is a function of their dimensional change with variability in moisture content and also the degree of cementation between grains.

Cap Stabilization for Reclaimed Uranium Sites

The reclamation and stabilization of uranium‐mill‐tailings sites requires engineering designs to protect against the disruption of tailings and the potential release of radioactive materials. The reclamation design is to be effective for 200‐1,000 years. This paper presents recently developed or refined techniques and methodologies used to evaluate uranium‐tailings‐reclamation plans designed to provide long‐term stability against failure modes. Specific cap‐design aspects presented include design flood selection, influence of fluvial geomorphology on site stabilization, stable slope prediction, slope stabilization using riprap, and riprap selection relative to rock quality and durability. Design relationships are presented for estimating flow through riprap, sizing riprap, and estimating riprap flow resistance for overtopping conditions. Guidelines for riprap‐layer thickness and gradation are presented. A riprap‐rating procedure for estimating rock quality and durability is also presented.

きょう炭層岩石のスレーキング特性 ＩＩＩ きょう炭層岩石の力学的諸特性に及ぼす水分の影響

Coal measure rocks in Japan tend to deteriorate their mechanical properties by the presence of water. Most rocks around roadways and workings in the coal mines are liable to be exposed to water from the strata and other sources. Therefore, knowledge of the effect of water on the mechanical properties of coal measure rocks is of great ignificance for strata control in coal mining operations such as the maintenance of roadway and the face support and for the utilization of these rocks as back filling materials.In the present paper durability of coal measure rocks for water is investigated by means of three different kinds of slaking tests. The practical applicability of these tests to coal measure rocks is discussed and the contributory factors to slaking and their correlation with other properties such as uniaxial compressive strength and montmorillonite content are also investigated.

Slake durability of rocks and its relation to slope stability : Kikuchi, K; Mimuro, T; Suzuki, M; Yoshinaka, R; Sato, N Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3–7 November, 1986P415–421. Publ Beijing: Science Press, 1986

Slake durability of rocks and its relation to slope stability : Kikuchi, K; Mimuro, T; Suzuki, M; Yoshinaka, R; Sato, N Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3–7 November, 1986P415–421. Publ Beijing: Science Press, 1986

Slake durability of rocks and its relation to slope stability : Kikuchi, K; Mimuro, T; Suzuki, M; Yoshinaka, R; Sato, N Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3–7 November, 1986P415–421. Publ Beijing: Science Press, 1986

Slake durability of rocks and its relation to slope stability : Kikuchi, K; Mimuro, T; Suzuki, M; Yoshinaka, R; Sato, N Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3–7 November, 1986P415–421. Publ Beijing: Science Press, 1986

Rock weathering in engineering time

Abstract The paper attempts a comprehensive review of in situ weathering of rock used in civil engineering construction. It also presents some new data on weathered rock from Britain which have been used to develop a proposed tentative Rock Durability Indicator scheme. This is based on simple engineering tests to help assess the potential performance of the rock in service. It is concluded that weathering in geological time can have significant influence, under certain circumstances, on the durability of aggregate or stone in-service. Durability is defined as the rock material's ability to resist degradation during its working life and is considered to be dependent on a number of parameters; viz. the original stage of weathering of the rock mass; the degree of imposed stressing during winning, production, placing and service; the climatic; topographical and hydrological environments in-service. The production and construction procedures can have an important influence on the mechanical strength of the material. Physical weathering processes and imposed loading generally have the most significant effect on deterioration but chemical weathering could be of significance in-service, especially in hot, wet climates. No one engineering test can be used as an absolute predictor of performance. Combinations of common mechanical and physical tests such as water absorption, specific gravity, point load strength, modified AIV and magnesium sulphate soundness can be used in various combinations to help assess potential durability. For a more complete evaluation, environmental factors such as the climate, topography and hydrological regimes need to be taken into account.

Improved Rock Durability Testing Techniques for Appalachian Valley Fills

Improved Rock Durability Testing Techniques for Appalachian Valley Fills

Use of the sand blast test to determine rock durability : Verhoef, P N W; Kuipers, T J; Verwaal, W Int Assoc Engng Geol BullN29, June 1984, P457–461 (paper to the International Symposium on Aggregates, Nice, 21–23 May 1984)

Use of the sand blast test to determine rock durability : Verhoef, P N W; Kuipers, T J; Verwaal, W Int Assoc Engng Geol BullN29, June 1984, P457–461 (paper to the International Symposium on Aggregates, Nice, 21–23 May 1984)

Internal texture of road base as a measure of aggregate durability

Research work done at the Australian Road Research Board and monash university (Melbourne, Australia) into the durability of crushed rock roadbase materials involved the comparison of material from roads with material subjected to repeated rolling loads under controlled laboratory conditions. The principal research method was the microscope examination of petrological thin sections prepared from undisturbed samples after impregnation with epoxy resin. It was observed that internal texture changes occurred as a result of the repeated loading. These were described and followed using a point counting procedure. It was postulated that the texture changes were related to rock durability on one hand, and to road condition on the other, thus providing a link between the geological characteristics of the rock and the in service performance and behaviour of the road built from these when crushed. The point counting method was adopted as a preliminary research method only and could be replaced by automatic image analysis techniques for routine examination of samples. The original research was done on a range of altered basaltic rocks but internal texture changes were later observed with schists and sandstones. Assessment of internal texture changes could be a basis for mathematically describing the relative durability of different rock types and for the indication of the remaining life of road pavements (a).

Thermodynamic interpretation of weathering indices and its application to engineering properties of rocks

Weathering indices typified by the Miura index ( W o m) that are the ratios of geochemically mobile to relatively immobile elements can be shown to be logarithmically related to the free energy of the weathering reaction. This can be demonstrated for silicate minerals; other extensive properties such as the moduli of elasticity and rigidity are similarly correlated. The mass strength envelope implied by the corresponding o-log W plot concurs well with plotted values for rocks, suggesting that the correlation is valid for intact rocks as well. By a combination of the Miura index and an index believed to show not only the state of weathering but also the susceptibility to further weathering (the Parker index W o p), it is possible to obtain estimates of the activation energy for the incongruent aqueous dissolution of minerals, which compare favourably with experimental determinations. Although the engineering behaviour of rocks is generally governed by physical parameters, and thus by short-term mechanical or physico-chemical forces, there are some instances where failure has been attributed to the chemistry of the rock itself. For these rocks a good correlation is obtained between a chemical weatherability index (log W o m/ W o p) and rock durability, as measured by the Los Angeles abrasion test.

The use of the sand-blast test to determine rock durability

The suitability of the sand-blast test to assess resistance of hard rocks against abrasion is investigated for eight different rock types. The test provides a good discrimination between different types of hard rock and is also sensitive to anisotropy in rock materials. A microscope study of the result of the impact of sand particles on the rock surface has been made in order to determine the applicability of the test to practical circumstances. Volume loss due to sand-blasting on hard rocks shows a correlation with tensile strength.