Category of breeds according to Protodyakonov. Well drilling - classification of rocks. Unified classification of rocks by drillability
| Category | Fortress degree | Breed | f |
| I | Extremely strong breeds | The strongest, densest and most viscous quartzites and basalts. Exceptional strength other breeds. | |
| II | Very strong breeds | Very hard granite-like rocks: quartz porphyry, very hard granite, siliceous schist, less hard than the above quartzites. The hardest sandstones and limestones. | |
| III | Strong breeds | Granite (dense) and granite rocks. Very hard sandstones and limestones. Quartz ore veins. Strong conglomerate. Very hard iron ores. | |
| IIIa | Same | Limestones (hard). Sturdy granite. Strong sandstones. Strong marble, dolomite. Pyrites. Ordinary sandstone. | |
| IV | Pretty strong breed | Iron ores. Sandy shales. | |
| IV | Same | Shale sandstones | |
| V | Medium breeds | Hard shale. Weak shale and limestone, soft conglomerate | |
| Va | Various slates (weak). Dense marl | ||
| VI | Pretty soft rocks | Soft slate, very soft limestone, chalk, rock salt, gypsum. Frozen ground: anthracite. Common marl. Destroyed sandstone, cemented pebbles and cartilage, rocky ground | |
| VIa | Same | hard coal | 1,5 |
| VII | soft rocks | Clay (dense). Soft coal, strong alluvial clay soil |
Table 1. The coefficient of strength f according to the scale of prof. MM. Protodyakonova Note. Characteristics of breeds from Y11a to X categories are omitted.
Protodyakonov proposed to put such a classification as the basis for assessing the labor of a worker in the extraction of coal and ores, and labor rationing. He believed that with any method of destruction of the rock and the method of its extraction, it is possible to evaluate the rock by the average mining coefficient. If one of the two types of rocks is more laborious when destroyed, for example, by explosion energy, then the rock will be stronger in any process of its destruction, for example, a combine tooth, a pick, a drill head blade when drilling, etc.
When developing such a scale, M.M. Protodyakonov introduced the concept fortress mountain breed. Contrary to the accepted concept strength material, estimated by one of the types of its stressed state, for example, temporary resistance to compression, tension, torsion, etc., the strength parameter allows you to compare rocks in terms of the complexity of destruction, in terms of mining. He believed that with the help of this parameter it is possible to estimate the totality of stresses of different nature acting during the destruction of the rock, as is the case, for example, in the destruction by an explosion.
MM. Protodyakonov developed a scale for the coefficient of rock strength. In the Soviet Union and then in Russia, the M.M. Protodyakonov was widely used in assessing the complexity of rock destruction and is still used today. It is convenient for a relative assessment of the strength of the rock during its destruction with the help of drilling and blasting.
The method of relative assessment of rock by strength, labor intensity during its destruction, as noted by many, has disadvantages; it is not used abroad, but it is not dispensed with in the technical literature of the Soviet Union and Russia.
The coefficient of rock strength according to M.M. Protodyakonov in the SI system is calculated by the formula:
f cr = 0.1*σ com
where σ compressive strength is uniaxial compression [MPa].
This classification is based on the strength coefficient of rocks f, which characterizes the strength of the mountains
crushing rocks under uniaxial compression. At-
It is assumed that a rock with a crushing strength of 100 kgf / cm 2 (9.8 × 10 6 N / m 2) has a strength coefficient equal to one. Thus, a rock with strength, for example, 1000 kgf / cm 2 (9.8 × 10 7 N / m 2), has a strength coefficient according to the classification of prof. MM. Protodyakonova:
those. the strength coefficient shows how many times a given breed is stronger than another, the strength of which is taken as a unit.
Prof. MM. Protodyakonov believed that the strength coefficient characterizes the breed in all production processes, i.e. if a given rock is stronger than another by a certain number of times, for example, during drilling, then it, as a rule, is as many times stronger than it during other production processes, for example, when blasting.
Classification prof. MM. Protodyakonov (Table 1.2) has 10 categories (from I to X), some of which are divided into subcategories (III-VII). The strongest breeds belong to category I, the weakest - to category X. Each group of rocks corresponds to a hardness coefficient from 0.3 to 20. This classification is still used at many mining enterprises in the CIS countries for an approximate assessment of rocks, as well as for integrated design and cost estimates.
Table 1.2
Classification of breeds M.M. Protodyakonova
| Breed category | Fortress degree | Rocks | Strength coefficient f |
| I | Extremely strong breeds | The strongest, densest and most viscous quartzites and basalts. Exceptional strength other breeds | ³ 20 |
| II | Very strong breeds | Very hard granite rocks. Quartz porphyry, very hard schist. Less strong than the above quartzites. The hardest sandstones and limestones | 15 |
| III | Strong breeds | Granite (dense) and granite rocks. Very hard sandstones and limestones. Quartz ore veins. Strong conglomerate. Very hard iron ores | 10 |
| IIIa | Same | Limestones (hard). Sturdy granite. Strong sandstones. Strong marble, dolomite, pyrites | 8 |
| IV | Pretty soft rocks | Ordinary sandstone. Iron ores | 6 |
| IVa | Same | Sandy shales. Shale sandstones | 5 |
The end of the table. 1.2
| Breed category | Fortress degree | Rocks | Strength coefficient f |
| V | Breeds of medium strength | Hard shale. Weak sandstone and limestone, soft conglomerate | 4 |
| Va | Same | Various shales (non-hard), dense marl | 3 |
| VI | Pretty soft rocks | Soft slate. Very soft limestone, chalk, rock salt, gypsum. Frozen ground, anthracite. Common marl. Destroyed sandstone, cemented pebble | 2 |
| VIa | Same | Crushed soil. Destroyed slate, compacted slate, compacted pebbles and crushed stone, hard coal. hardened clay | 1,5 |
| VII | soft rocks | Clay (dense). Soft coal. Strong sediments, clayey soil | 1,0 |
| VIIa | Same | Light sandy clay, loess, gravel | 0,8 |
| VIII | Earthy rocks | Plant land. Peat, light loam, wet sand | 0,6 |
| IX | loose sands | Sand, scree, fine gravel, bulk earth, mined coal | 0,5 |
| X | floating rocks | Quicksand, swampy soil, liquefied loess and other liquefied rocks, soils | 0,3 |
For operational standardization, the classification of breeds by prof. MM. Protodyakonova is unsuitable. For these purposes, classifications are used for drillability and explosiveness.
Unified classification of rocks by drillability
A special commission under the former Institute of Mining of the Academy of Sciences of the USSR on the basis of research by prof. A.F. Sukhanov developed a draft unified classification by drillability. The drillability of rocks in this classification is characterized by the net speed of drilling a hole under the following standard test conditions: type of hammer drill PR-19 (PR-22); compressed air pressure ¾ 4.5 kgf / cm 2 (0.45 MPa); characteristics of the drilling tool: diameter of the drill head ¾ 42 mm; drill blade shape ¾ cross; injection
blade sharpening ¾ 90°; rod length ¾ 1 m; drilling depth ¾ to 1 m.
In the case of an experiment under conditions other than standard, appropriate correction factors are introduced. After determining the drilling speed according to the classification, the closest value of the tabular speed is found and the rock belongs to this class. On this principle, a large number of classifications have been compiled for certain conditions of mines, quarries, pools (Table 1.3).
In parallel with the creation of classifications according to the drilling speed, the classification of rocks according to the energy intensity of drilling was carried out for certain types of drilling machines. The advantage of such classifications is that energy intensity makes it possible to evaluate, in addition to drillability, the effectiveness of the method used (machine, machine tool), since the lower the energy intensity, the more efficiently the process of rock destruction and removal of destruction products from the bottomhole is implemented. The value of energy intensity is taken as a measure of efficiency a:
where BUT¾ drilling energy costs, BUT = Nt; N¾ power consumption, kW; t¾ operating time of the machine, machine tool when drilling out the volume of rock V P .
One of the first such classifications was made in
1867 for drilling wells in the quarries of the Kolyvano-Vos-Kresensky plants (Urals). After the widespread use of percussion-rope machines for drilling blast holes, Ya.B. Zaidman and P.P. Nazarov in the 1930s developed a classification of rocks by energy intensity for this drilling method. Prof. I.A. Tangaev developed a classification according to energy intensity in relation to the cone drilling method. At the same time, he showed that the energy intensity is affected by the strength and fracturing of rocks, i.e. the more fractured the rock, the lower the energy intensity of its drilling, but the easier it is destroyed during an explosion and the more productive it is loaded by excavators. Thus, I.A. Tangaev was able to estimate the explosiveness of rocks in the drilled volume of the block by the energy intensity of roller drilling, which could not be done using other classification criteria. Similar information about the properties of the mass to be drilled (strength and fracturing) can be obtained from the net drilling speed under certain conditions (strength) and the level of low-frequency vibrations of the drilling string (fracturing). This technique was developed at MGI.
Classification of rocks by explosiveness is based on determining the value of the specific consumption of a certain explosive under standard blasting conditions. In this case, as a result of the explosion, the rock should be destroyed into pieces of a certain size.
At present, many mines and quarries have developed local classifications of rock masses by explosiveness, which are based on the properties of massifs: fracturing and strength of units, which most significantly affect the calculated specific consumption of explosives. Comparative analysis of such classifications shows that each of them contains easily exploded, difficultly exploded and very difficult to explode rock masses. Sometimes intermediate classes are introduced in the classification above the average explosiveness, etc. Comparison of arrays with the same explosive characteristics shows that the calculated specific consumption in them can differ by a factor of 2 or more (for example, for hard-to-blast arrays from 0.42 to 0.850 kg / m 3, etc.).
An objective comparison of the explosiveness of rocks according to such "local" classifications is impossible. Therefore, MHI, together with VNIITsvetmet (authors B.N. Kutuzov and V.F. Pluzhnikov), developed a general classification of rock masses by explosiveness for open pits, based on standard conditions for its assessment. The following were accepted as standard conditions for conducting experimental explosions: ledge height 12-15 m, slope angle 65-70 °, borehole diameter 243-269 mm, explosive ¾ grammonite 79/21; blasting scheme is multi-row, short-circuit blasting with slowdowns along the diagonals, the size of the overdrill is 2 m, the size of the stemming is 6 m.
The most common classification of rocks by strength, compiled by Professor M.M. Protodyakonov. This classification is based on the fact that the resistance of a rock to any type of destruction can be expressed by one specific number - the rock strength coefficient (f), which shows how many times the strength of a given rock is more or less than the strength of the rock, conventionally taken as a unit.
| Breed category | Fortress degree | breeds | Strength coefficient, f |
| I | extremely strong breeds | The strongest, densest and most viscous quartzites and basalts. Exceptional strength other breeds | 20 |
| II | very strong breeds | Very hard granite rocks. Porphyry quartz, very hard granite, chert. Less strong than the above quartzites. The hardest sandstones and limestones | 15 |
| III | strong breeds | Granite (dense) and granite rocks. Very hard sandstones and limestones. Quartz ore veins. Strong conglomerate. Very hard iron ores | 10 |
| IIIa | strong breeds | Limestones (hard). Sturdy granite. Strong sandstones. Strong marble. Dolomite. Pyrites | 8 |
| IV | quite strong breeds | Ordinary sandstone. Iron ores | 6 |
| IVa | quite strong breeds | Sandy shales. Shale sandstones | 5 |
| V | medium breeds | Hard shale. Weak sandstone and limestone, soft conglomerate | 4 |
| Va | medium breeds | Various shales (weak). Dense marl | 3 |
| VI | fairly soft rocks | Soft slate, very soft limestone, chalk, rock salt, gypsum. Frozen ground, anthracite. Common marl. Shattered sandstone, cemented pebbles, rocky ground | 2 |
| VIa | fairly soft rocks | Crushed soil. Destroyed shale, compacted pebbles and rubble. Strong coal. hardened clay | 1,5 |
| VII | soft rocks | Clay (dense). Soft coal. Strong deposit, clay soil | 1 |
| VIIa | soft rocks | Light sandy clay, loess, gravel | 0,8 |
| VIII | earthy rocks | Plant land. Peat. Light loam, wet sand | 0,6 |
| IX | loose rocks | Sand, scree, fine gravel, bulk earth, mined coal | 0,5 |
| X | floating rocks | Quicksand, swampy soil, liquefied loess and other liquefied soils | 0,3 |
Note: For f=1, the strength of the rock is taken, which collapses at a pressure of 100 kg/cm 2 on it.
Approximately the strength coefficient is equal to 0.01 of the ultimate strength of the rock under uniaxial compression in kg/cm 2 . For some, especially strong breeds, this coefficient can reach 25 or more.
The coefficient of rock strength according to M.M. Protodyakonov in the SI system is calculated by the formula:
fcr = 0.1σcompressive strength, where σcompressive strength [MPa].
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Classification of rocks by strength and drillability
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This classification is based on the idea that the resistance of the rock to any type of destruction (drilling in various ways, blasting, etc.).
Rock strength is a complex characteristic of the rock, determined by a number of its physical and mechanical properties that affect the process of its destruction during drilling. The strength of a rock is a constant value, independent of the method of drilling.
Approximately, the strength coefficient I can be taken equal to 0.01 of the ultimate strength of the rock in uniaxial compression (I = 0.01 oszh).
The drillability of the rock is the value of the deepening of the well per unit of time of pure drilling (mechanical drilling speed). It is evaluated in m/h, cm/min, mm/min.
The drillability of rocks is established empirically for certain rocks and rock cutting tools under rational drilling regimes. Since the mechanism of destruction of rocks is different with different drilling methods, the drillability of the same rock with different drilling methods will be different. Drillability of the rock is characterized by the following indicators: mechanical drilling speed, the amount of penetration to the allowable wear of the rock cutting tool, the time spent on driving 1 m of the well. These values depend not only on the properties of the rock, but also on the type and design of the rock cutting tool and the parameters of the drilling mode. With the improvement of rock cutting tools and technological parameters, the “drillability” of rocks increases.
Currently, there are a large number of rock drillability scales with various rock cutting tools and in various ways. These scales are not linked to each other.
Rock formations for rotary core drilling are divided into twelve categories x. The criterion for assigning a rock to one or another category of drillability is the depth of the well for 1 hour of pure drilling under certain conditions (type and diameter of the drill bit, depth of the well, etc.). In case of deviations from the established (standard) conditions, correction factors are introduced.
According to plasticity, L.A. Shreiner divided the rocks into six categories.
Volumetric destruction occurs when a stress occurs at the contact of the cutters (teeth) of the rock cutting tool with the rock that exceeds the indentation hardness of the rock (critical stress):
When drilling, not only the rock is destroyed; at the same time, wear (blunting) of the incisors occurs. In this case, the destruction of the rock during drilling will occur only due to the friction forces that arise at the contact of the blades with the rock. This type of destruction is inefficient.
Rock classification for mechanical rotary drilling
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Characteristic breeds for each category |
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Peat and vegetation layer without roots; loose loess, sands (not quicksand), sandy loam without pebbles and gravel; wet silt and silty soils; loess-like loams; tripoli: chalk is weak. |
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Peat and vegetation layer with roots or small admixture of small (up to 3 cm) pebbles and rubble; sandy loam and loam with an admixture of up to 20% small (up to 3 cm) pebbles or crushed stone; sands are dense; loam is dense; loess; marl loose; quicksand without pressure; ice; clays of medium density (tape and plastic); a piece of chalk; diatomite; soot; rock salt (halite); completely kaolinized weathering products of igneous and metamorphosed rocks; ocher iron ore. |
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Loams and sandy loams with an admixture of over 20% small (up to 3 cm) pebbles or crushed stone; the forest is dense; gruss; pressure quicksand; clays with frequent interlayers (up to 5 cm) of weakly cemented sandstones and marls, dense, marl, gypsum, sandy; clayey weakly cemented siltstones; sandstones weakly cemented with clayey and limestone cement; marl; limestone-shell rock; chalk is dense; magnesite; gypsum fine-crystalline, weathered; coal is weak; brown coal; talc shales, destroyed of all varieties; manganese ore; iron ore, oxidized, loose; clayey bauxite. |
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Pebble, consisting of small pebbles of sedimentary rocks; frozen water-bearing sands, silt, peat; siltstones dense clayey; clayey sandstones; marl is dense; loose limestones and dolomites; magnesite is dense; porous limestones, tuffs; clay flasks; gypsum crystal; anhydrite; potassium salts; coal of medium hardness; brown coal is strong; kaolin (primary); clayey, sandy-argillaceous, combustible, carbonaceous, silty shales; serpentinites (serpentines) strongly weathered and talcized; loose skarns of chlorite and amphibole-micaceous composition; crystalline apatite; strongly weathered dunites, peridotites; weathered kimberlites; martite and similar ores, strongly weathered; soft viscous iron ore; bauxites. |
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Pebble-gravel soils; frozen gravel, associated with clay or sandy-clay material with ice interlayers; frozen: coarse-grained sand and gruss, dense silt, sandy clays, sandstones on calcareous and ferruginous cement; siltstones; mudstones; argillite-like clays, very dense, dense strongly sandy; a conglomerate of sedimentary rocks on sandy-argillaceous or other porous cement; limestones; marble; marl dolomites; anhydrite is very dense; flasks porous weathered; hard coal; anthracite, nodular phosphorites; clay-mica, mica, talc-chlorite, chlorite, chlorite-clay, sericite shales; serpentinites (serpentines); weathered albitophyres, keratophyres; serpentinized volcanic tuffs; weathered dunites; brecciated kimberlites; martite and similar ores, loose. |
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Anhydrites are dense, contaminated with tuffaceous material; dense frozen clays; dense clays with interlayers of dolomite and siderites; sedimentary rock conglomerate on calcareous cement; feldspar, quartz-calcareous sandstones; siltstones with inclusion of quartz; limestones dense dolomitic, skarnirovannye; dolomites are dense; flasks; clayey, quartz-sericite, quartz-mica, quartz-chlorite, quartz-chlorite-sericite, roofing shales; chloritized and sheared albitophyres, keratophyres, porphyrites; gabbro; mudstones, weakly silicified; dunites unaffected by weathering; weathered peridotites; amphibolites; pyroxenites coarse-grained; talc-carbonate rocks; apatites, epidote-calcite skarns; loose pyrites; brown ironstones are spongy; hematite-martite ores; siderites. |
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Argillites are silicified; gravel of igneous and metamorphic rocks (river rock); crushed stone without boulders; conglomerates with pebbles (up to 50%) of igneous rocks on sandy-argillaceous cement; sedimentary rock conglomerates on siliceous cement; quartz sandstones; dolomites are very dense; silicified feldspar sandstones, limestones; kaolin agalmatolitic; the flasks are strong and dense; phosphorite plate; weakly silicified shales; amphibole-magnetite, cummingtonite, hornblende, chlorite-hornblende; weakly sheared albitophyres, keratophyres, porphyries, porphyrites, diabase tuffs; affected by weathering: porphyries, porphyrites; coarse and medium-grained weathered granites, syenites, diorites, gabbro and other igneous rocks; pyroxenites, ore pyroxenites; basaltic kimberlites; calcite-bearing augite-garnet skarns; porous quartz (fractured, spongy, ocherous); brown iron ore porous porous; chromites; sulfide ores; martite-siderite and hematite ores; amphibole-magnetite ores. |
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Siliceous mudstones; conglomerates of igneous rocks on calcareous cement; silicified dolomites; silicified limestones and dolomites; dense bedded phosphorites; silicified schists: quartz-chlorite, quartz-sericite, quartz-chlorite-epidote, mica; gneisses; medium-grained albitophyres and keratophyres; weathered basalts; diabase; porphyries and porphyrites; andesites; diorites unaffected by weathering; labradorites; peridotites; fine-grained, weathered granites, syenites, gabbro; weathered granite-gneisses, pegmatites, quartz-tourmaline rocks; skarns coarse and medium-grained crystalline augite-garnet, augite-epidote; epidositis; quartz-carbonate and quartz-barite rocks; brown ironstones are porous; hydrohematite ores are dense; hematite, magnetite quartzites; dense pyrite; diaspore bauxite. |
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Basalts unaffected by weathering; conglomerates of igneous rocks on siliceous cement; karst limestones; siliceous sandstones, limestones; siliceous dolomites; bedded silicified phosphorites; siliceous shales; quartzite magnetite and hematite thin-banded, dense martite-magnetite; hornfelses are amphibole-magnetite and syricitized; albitophyres and keratophyres; trachytes; silicified porphyry; diabases are fine-crystalline; silicified tuffs; hornfelsed; weathered liparites, microgrants; coarse and medium-grained granites, granite-gneisses, granodiorites; syenites; gabbro-norites; pegmatites; beresites; finely crystalline augite-epidoto-garnet skarns; datolite-garnet-hedenbergite; coarse-grained skarns, garnet; silicified amphibolite, pyrites; quartz-tourmaline rocks not affected by weathering; brown ironstones are dense; quartz with a significant amount of pyrites; barytes are dense. |
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Boulder-pebble deposits of igneous and metamorphosed rocks; drain quartz sandstones; jaspilites; weathered, phosphate-siliceous rocks; quartzites uneven-grained; hornfelses with disseminated sulfides; quartz albitophyres and keratophyres; liparites; fine-grained granites, granite-gneisses and granodiorites; microgranites; pegmatites are dense, strongly quartz; fine-grained garnet, datolite-garnet skarns; magnetite and martite ores, dense, with interlayers of hornfelses; silicified brown iron ore; vein quartz; porphyrites are strongly silicified and hornfelsed. |
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Albitophyres fine-grained, hornfelsed; jaspilites unaffected by weathering; jasper-like siliceous shales; quartzites; hornfelses glandular, very hard; dense quartz; corundum rocks; jaspilites are hematite-martite and hematite-magnetite. |
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Completely unaffected by weathering monolithic-confluent jaspilites, flint, jaspers, hornfelses, quartzites, aegirine and corundum rocks. |
Classification of characteristic representatives of rocks according to drillability during auger drilling
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Characteristic representatives of rocks for each category |
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Vegetation layer and peat with a small admixture of pebbles and gravel, silty soils. Loess-like loose loams, loose loess, tripoli. |
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Loose sands and sandy-clay soils with an admixture (up to 10%) of small pebbles and gravel. Clays are tape, plastic, sandy. Diatomaceous earth. Soot. |
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Sandy-clay soils with an admixture (10-30%) of small pebbles, crushed stone and gravel. Loose marls, dense clays and loams, compacted loess, weak chalk. Dry sands, brown coal, quicksand. |
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Sandy-clayey soils with a significant (over 30%) admixture of pebbles and crushed stone. Dense viscous clays, boulder clays, kaolin. Porous limestone-shell rock, dense chalk, gypsum, bauxites, anhydrite, phosphorites, flask, rock salt, coal. Frozen soils; sand, silt, peat, loam. |
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Frozen clays are argillite-like, very dense; clayey sandstone is dense; coarse-grained sandstone with an admixture of pebbles. Dense silt and sludge with ice layers. Ice. |
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Frozen: pebbles bound by clayey or sandy-clayey materials; dense clays with inclusions of dolomites and siderites; clays are dense. Boulder-pebble deposits. |
Classification of rocks by drillability for percussion drilling in the exploration of alluvial deposits
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Vegetation layer and loose sands, peat and vegetation layer with an admixture of clay and sand, chernozem of normal moisture, stable poorly cemented (non-floating) sands and loose sandy-argillaceous pounds (sandy loam) without pebbles and crushed stone, loose loess; water-bearing silts and swamp pounds that do not give plugs. |
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Unbound small-pebble and sandy-clayey pounds, stable sands and sandy loams bound by clay, with a small admixture of pebbles and crushed stone, not bound by clay; sandy-clay pounds with a small amount of pebbles and rubble; loess, loess-like loams, kaolin; quicksand, giving cork and ice. |
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Clay and clay-bound pebbly pounds with occasional boulders; coarse pebble and sandy-shabne soils, weakly cemented with clay, dense dry or damp, oily, viscous clay, dense loams; loose kaolinized weathering products of igneous and metamorphosed rocks, coal, loose marl, clay shales, porous limestones and tuffs; heavily destroyed bedrock, converted into gruss and other small weathering products. |
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Densely cemented large-pebble soils with rare boulders; hard coal, rock salt, bauxite, marl, mudstone, flask, shell limestone, magnesite, wet soft iron ore; dense dry or greasy viscous clay (meshnika) with large pebbles, crushed stone and ribs; coarse pebble soils cemented with dense greasy clay (meshnik); dense gravel soils cemented with clay, with large angular fragments (eluvium, boulder clay); destroyed small collapsible (in a raft): sandstones, limestones; clayey, sandy-argillaceous, carbonaceous, micaceous and calcareous shales; dense marls; steel-forged and dense rocks with frequent cracks. |
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Crystalline gypsum, hard coal with inclusions of pyrite and silicon concretions; dolomites, a conglomerate ("baking" or "burner") with a sandy-clay substance between pebbles held together by ferruginous, calcareous and other medium-strength cement; heavily bouldery soils containing from 20 to 40% of large (up to 0.3 m in diameter) boulders and angular, randomly located fragments of the raft (ribs, slabs, blocks); large collapsible fractured (in the raft) sandstones; limestones sandy-argillaceous, clayey, carbonaceous, talc and micaceous shales and other bedrocks of medium fracture. |
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Heavily bouldery soils containing over 40% of large boulders (diameter up to 0.5 m), requiring the use of blasting; fissured (in the raft); metamorphic and crystalline schists, igneous (granites, diorites, syenites, gabbro, etc.) and hard sedimentary (limestones, dolomites, sandstones, thick-layered shales, etc.) rocks. |
Classification of rocks by drillability in percussion-rope drilling (excluding exploration of alluvial deposits)
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Rocks typical for each category |
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Peat and vegetative layer without roots, loose sands, silty rocks, bog pounds, loose sandy-argillaceous pounds (sandy loam) without pebbles and crushed stone, loess-like loams; loose loess, tripol. |
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Peat and vegetative layer with roots or small admixture of small pebbles and favium; loose sandy-clayey pounds with an admixture (up to 20%) of small pebbles and favia; varieties of sands not included in categories 1 and 3; banded, plastic, sandy clays, diatomite, soot, moistened weak chalk. |
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Sandy-clayey pounds with a significant admixture (over 20%) of crushed stone, gravel and small pebbles; loose marls; dense clays and loams, compacted loess, chalk; dry sands, clean ice. |
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Sandy-argillaceous pounds with a significant admixture (over 20%) of crushed stone, favium and small pebbles; loose marls; dense clays and loams, compacted loess, chalk; dry sands, clean ice. |
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Small gravel without boulders; slate, roofing, mica schists; sandstones on calcareous and ferruginous cement; limestone, dolomite, marble; mudstones, anhydrites and spongy brown ironstones; strong coal; weathered igneous rocks: fanites, syenites, diorites, gabbro, etc.; sedimentary rock conglomerates on lime cement; frozen pounds: shallow sands and silt, sandy clays, dense wet clays, pebbles connected by clay material with ice layers. |
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Large gravel with few small boulders; silicified shales, limestones and sandstones; coarse-grained igneous rocks: fanites, diorites, syenites, gabbro, gneisses, porphyries and pegmatites, sedimentary rock conglomerates on siliceous cement. |
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In my work, I often come across mining and geological forecasting passports, where the most valuable information for me is the characteristics of the rocks. Someone looks at violations, water inflow, profile, and for the calculation I need the power and compressive strength of rocks. So, the idea of this record arose when, instead of the strength of the rocks, I received the strength coefficient according to M.M. Protodyakonov. Here I want to tell you what the strength coefficient is in general, how it is calculated and how to get the compressive strength of rocks from it.
Fortress of rocks- characteristics of the resistance of rocks to their mining - technological destruction.
This concept of a fortress was introduced by prof. MM. Protodyakonov, who proposed a strength coefficient for its quantitative assessment f, in the first approximation proportional to the compressive strength of the rock. He developed a scale of rocks by strength, according to which all rocks are divided into 10 categories.
| Breed category | Fortress degree | breeds | Strength coefficient f |
|---|---|---|---|
| I | Supremely strong | The strongest, densest and most viscous quartzites and basalts. Exceptional strength other breeds 20. | 20 |
| II | Very strong | Very hard granite rocks. Porphyry quartz, very hard granite, chert. Less strong than the above quartzites. The hardest sandstones and limestones. | 15 |
| III | Strong | Granite (dense) and granite rocks. Very hard sandstones and limestones. Quartz ore veins. Strong conglomerate. Very hard iron ores | 10 |
| IIIa | Strong | Limestones (hard). Sturdy granite. Strong sandstones. Strong marble. Dolomite. Pyrites | 8 |
| IV | Pretty strong | Ordinary sandstone. Iron ores | 6 |
| IVa | Pretty strong | Sandy shales. Shale sandstones | 5 |
| V | medium fortress | Hard shale. Weak sandstone and limestone, soft conglomerate | 4 |
| Va | medium fortress | Various shales (weak). Dense marl | 3 |
| VI | Pretty soft | Soft slate, very soft limestone, chalk, rock salt, gypsum. Frozen ground, anthracite. Common marl. Shattered sandstone, cemented pebbles, rocky ground | 2 |
| VIa | Pretty soft | Crushed soil. Destroyed shale, compacted pebbles and rubble. Strong coal. hardened clay | 1,5 |
| VII | Soft | Clay (dense). Soft coal. Strong deposit, clay soil | 1 |
| VIIa | Soft | Light sandy clay, loess, gravel | 0,8 |
| VIII | earthy | Plant land. Peat. Light loam, wet sand | 0,6 |
| IX | Bulk | Sand, scree, fine gravel, bulk earth, mined coal | 0,5 |
| X | buoyant | Quicksand, swampy soil, liquefied loess and other liquefied soils | 0,3 |
In the simplest case, the strength of rocks can be calculated by the formula:
$$f=\sigma_(szh) \times 10^(-7)$$
where: σ compress- compressive strength of rocks, Pa
More precisely, the relationship between σ compress and f in the region of large values σ compress can be expressed by the empirical formula:
$$f=0.33 \times 10^(-7) \sigma_(sg) + 0.58 \times 10^(-3) \sqrt( \sigma_(sg))$$
There are other formulas for the relationship between the strength coefficient of rocks and their strength parameters. For example, the formula L.I. Baron:
$$f=\frac(\sigma_(sg))(30) + \sqrt( \frac( \sigma_(sg))(3))$$
Here σ compress measured in MPa, which is somewhat more convenient, because in practice, geologists characterize rocks, where strength is presented in these units.
Formula L.I. Barona taken from a 1972 book, σ compress it was expressed in kgf / cm 2, but with the transition to the SI system, the use of these units is not recommended, so the formula has undergone minor changes.
Now it's time to return to the question that started this post. How to get the compressive strength of the rock from the strength coefficient σ compress.
If you need to find out the approximate tensile strength, then everything is simple, we multiply f by 10, we get σ compress in MPa.
But if we want to use the empirical formulas f, there may be difficulties, because simply substitute the value of the strength coefficient and it will not work to obtain a strength characteristic from it.
In the work of A.S. Tanina presented formulas for three intervals within 1 ≤ f≤ 20 which can be calculated σ compress:
To be honest, I did not use these formulas. Of course I checked them out. When substituting the boundary values of the intervals f we get σ compress, which differs by only 0.4 MPa in intervals 1 and 2, 2 and 3.
Finally, to find σ compress I used the MS Excel function - Selection of a parameter. From my point of view, this is the most obvious and correct way to determine the compressive strength of the rock through the fortress f.