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65-581: The Pikeville Cut-Through is a rock cut in Pikeville , Kentucky , United States , created by the U.S. Army Corps of Engineers , through which passes a four-lane divided highway ( Corridor B , numbered as U.S. Route 23 (US 23), US 119 , US 460 , and KY 80 ), a railroad line ( CSX ' Big Sandy Subdivision ), and the Levisa Fork of the Big Sandy River . It is one of

130-420: A chemically pure compound, such as nitroglycerin , or a mixture of a fuel and an oxidizer , such as black powder or grain dust and air. Some chemical compounds are unstable in that, when shocked, they react, possibly to the point of detonation. Each molecule of the compound dissociates into two or more new molecules (generally gases) with the release of energy. The above compositions may describe most of

195-634: A degree of water resistance. Explosives based on ammonium nitrate have little or no water resistance as ammonium nitrate is highly soluble in water and is hygroscopic. Many explosives are toxic to some extent. Manufacturing inputs can also be organic compounds or hazardous materials that require special handling due to risks (such as carcinogens ). The decomposition products, residual solids, or gases of some explosives can be toxic, whereas others are harmless, such as carbon dioxide and water. Examples of harmful by-products are: "Green explosives" seek to reduce environment and health impacts. An example of such

260-402: A measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances. The potential energy stored in an explosive material may, for example, be: Explosive materials may be categorized by the speed at which they expand. Materials that detonate (the front of the chemical reaction moves faster through the material than

325-433: A number of more exotic explosive materials, and exotic methods of causing explosions. Examples include nuclear explosives , and abruptly heating a substance to a plasma state with a high-intensity laser or electric arc . Laser- and arc-heating are used in laser detonators, exploding-bridgewire detonators , and exploding foil initiators , where a shock wave and then detonation in conventional chemical explosive material

390-413: A place of safety. The uncertainty of this method led to many accidents and various measures were introduced to improve safety for those involved. One was replacing the iron wire, by which the passage for the gunpowder is formed, with one of copper, to eliminate sparking that could ignite the powder prematurely. Another was the use of a safety fuse . This consisted of small train of gunpowder inserted in

455-685: A practical measure, primary explosives are sufficiently sensitive that they can be reliably initiated with a blow from a hammer; however, PETN can also usually be initiated in this manner, so this is only a very broad guideline. Additionally, several compounds, such as nitrogen triiodide , are so sensitive that they cannot even be handled without detonating. Nitrogen triiodide is so sensitive that it can be reliably detonated by exposure to alpha radiation . Primary explosives are often used in detonators or to trigger larger charges of less sensitive secondary explosives . Primary explosives are commonly used in blasting caps and percussion caps to translate

520-399: A reaction to be classified as a detonation as opposed to just a deflagration, the propagation of the reaction shockwave through the material being tested must be faster than the speed of sound through that material. The speed of sound through a liquid or solid material is usually orders of magnitude faster than the speed of sound through air or other gases. Traditional explosives mechanics

585-418: A rock tunnel have a high capital cost, but because they are usually quicker than a drill and blast tunnel the price per metre of tunnel is lower. This means that shorter tunnels tend to be less economical to construct with a TBM and are therefore usually constructed by drill and blast. Managing ground conditions can also have a significant effect on the choice with different methods suited to different hazards in

650-735: A smaller number are manufactured specifically for the purpose of being used as explosives. The remainder are too dangerous, sensitive, toxic, expensive, unstable, or prone to decomposition or degradation over short time spans. In contrast, some materials are merely combustible or flammable if they burn without exploding. The distinction, however, is not very clear. Certain materials—dusts, powders, gases, or volatile organic liquids—may be simply combustible or flammable under ordinary conditions, but become explosive in specific situations or forms, such as dispersed airborne clouds , or confinement or sudden release . Early thermal weapons , such as Greek fire , have existed since ancient times. At its roots,

715-401: A specific role in the rock support such as the combination of rock bolting and shotcrete. Explosive material An explosive (or explosive material ) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light , heat , sound , and pressure . An explosive charge is

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780-618: A thermodynamically favorable process in addition to one that propagates very rapidly. Thus, explosives are substances that contain a large amount of energy stored in chemical bonds . The energetic stability of the gaseous products and hence their generation comes from the formation of strongly bonded species like carbon monoxide, carbon dioxide, and nitrogen gas, which contain strong double and triple bonds having bond strengths of nearly 1 MJ/mole. Consequently, most commercial explosives are organic compounds containing –NO 2 , –ONO 2 and –NHNO 2 groups that, when detonated, release gases like

845-526: A water-proof cord, which burns at a steady and uniform rate. This in turn was later replaced by a long piece of wire that was used to deliver an electric charge to ignite the explosive. The first to use this method for underwater blasting was Charles Pasley who employed it in 1839 to break up the wreck of the British warship HMS Royal George which had become a shipping hazard at Spithead . An early major use of blasting to remove rock occurred in 1843 when

910-709: Is mining . Whether the mine is on the surface or is buried underground, the detonation or deflagration of either a high or low explosive in a confined space can be used to liberate a fairly specific sub-volume of a brittle material (rock) in a much larger volume of the same or similar material. The mining industry tends to use nitrate-based explosives such as emulsions of fuel oil and ammonium nitrate solutions, mixtures of ammonium nitrate prills (fertilizer pellets) and fuel oil ( ANFO ) and gelatinous suspensions or slurries of ammonium nitrate and combustible fuels. In materials science and engineering, explosives are used in cladding ( explosion welding ). A thin plate of some material

975-427: Is a pure substance ( molecule ) that in a chemical reaction can contribute some atoms of one or more oxidizing elements, in which the fuel component of the explosive burns. On the simplest level, the oxidizer may itself be an oxidizing element , such as gaseous or liquid oxygen . The availability and cost of explosives are determined by the availability of the raw materials and the cost, complexity, and safety of

1040-402: Is an important consideration in selecting an explosive for a particular purpose. The explosive in an armor-piercing projectile must be relatively insensitive, or the shock of impact would cause it to detonate before it penetrated to the point desired. The explosive lenses around nuclear charges are also designed to be highly insensitive, to minimize the risk of accidental detonation. The index of

1105-440: Is an important element influencing the yield of the energy transmitted for both atmospheric over-pressure and ground acceleration. By definition, a "low explosive", such as black powder, or smokeless gunpowder has a burn rate of 171–631 m/s. In contrast, a "high explosive", whether a primary, such as detonating cord , or a secondary, such as TNT or C-4, has a significantly higher burn rate about 6900–8092 m/s. Stability

1170-520: Is based on the shock-sensitive rapid oxidation of carbon and hydrogen to carbon dioxide, carbon monoxide and water in the form of steam. Nitrates typically provide the required oxygen to burn the carbon and hydrogen fuel. High explosives tend to have the oxygen, carbon and hydrogen contained in one organic molecule, and less sensitive explosives like ANFO are combinations of fuel (carbon and hydrogen fuel oil) and ammonium nitrate . A sensitizer such as powdered aluminum may be added to an explosive to increase

1235-443: Is created by laser- or electric-arc heating. Laser and electric energy are not currently used in practice to generate most of the required energy, but only to initiate reactions. To determine the suitability of an explosive substance for a particular use, its physical properties must first be known. The usefulness of an explosive can only be appreciated when the properties and the factors affecting them are fully understood. Some of

1300-452: Is evaluated by a tailored series of tests to assess the material for its intended use. Of the tests listed below, cylinder expansion and air-blast tests are common to most testing programs, and the others support specific applications. In addition to strength, explosives display a second characteristic, which is their shattering effect or brisance (from the French meaning to "break"). Brisance

1365-472: Is important in determining the effectiveness of an explosion in fragmenting shells, bomb casings, and grenades . The rapidity with which an explosive reaches its peak pressure ( power ) is a measure of its brisance. Brisance values are primarily employed in France and Russia. The sand crush test is commonly employed to determine the relative brisance in comparison to TNT. No test is capable of directly comparing

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1430-400: Is placed atop a thick layer of a different material, both layers typically of metal. Atop the thin layer is placed an explosive. At one end of the layer of explosive, the explosion is initiated. The two metallic layers are forced together at high speed and with great force. The explosion spreads from the initiation site throughout the explosive. Ideally, this produces a metallurgical bond between

1495-473: Is the ability of an explosive to be stored without deterioration . The following factors affect the stability of an explosive: The term power or performance as applied to an explosive refers to its ability to do work. In practice it is defined as the explosive's ability to accomplish what is intended in the way of energy delivery (i.e., fragment projection, air blast, high-velocity jet, underwater shock and bubble energy, etc.). Explosive power or performance

1560-411: Is the lead-free primary explosive copper(I) 5-nitrotetrazolate, an alternative to lead azide . Explosive material may be incorporated in the explosive train of a device or system. An example is a pyrotechnic lead igniting a booster, which causes the main charge to detonate. The most widely used explosives are condensed liquids or solids converted to gaseous products by explosive chemical reactions and

1625-407: Is used to describe an explosive phenomenon whereby the decomposition is propagated by a shock wave traversing the explosive material at speeds greater than the speed of sound within the substance. The shock front is capable of passing through the high explosive material at supersonic speeds   —   typically thousands of metres per second. In addition to chemical explosives, there are

1690-748: The Blue Ridge Tunnel in the United States, built in the 1850s), it was not until more powerful (and safer) explosives , such as dynamite (patented 1867), as well as powered drills were developed, that its potential was fully realised. Drilling and blasting was successfully used to construct tunnels throughout the world, notably the Fréjus Rail Tunnel , the Gotthard Rail Tunnel , the Simplon Tunnel ,

1755-573: The Jungfraubahn and even the longest road tunnel in the world, Lærdalstunnelen , are constructed using this method. In 1990, 2.1 billion kg of commercial explosives were consumed in the United States (12 m per capita), representing an estimated expenditure of 3.5 to 4 billion 1993 dollars on blasting. In this year the Soviet Union was the leader in total volume with 2.7 billion kg of explosives consumed (13 m per capita), and Australia had

1820-425: The speed of sound ) are said to be "high explosives" and materials that deflagrate are said to be "low explosives". Explosives may also be categorized by their sensitivity . Sensitive materials that can be initiated by a relatively small amount of heat or pressure are primary explosives and materials that are relatively insensitive are secondary or tertiary explosives . A wide variety of chemicals can explode;

1885-501: The British civil engineer William Cubitt used 18,000 lbs of gunpowder to remove a 400-foot-high chalk cliff near Dover as part of the construction of the South Eastern Railway . About 400,000 cubic yards of chalk was displaced in an exercise that it was estimated saved the company six months time and £7,000 in expense. While drilling and blasting saw limited use in pre-industrial times using gunpowder (such as with

1950-413: The aforementioned (e.g., nitroglycerin , TNT , HMX , PETN , nitrocellulose ). An explosive is classified as a low or high explosive according to its rate of combustion : low explosives burn rapidly (or deflagrate ), while high explosives detonate . While these definitions are distinct, the problem of precisely measuring rapid decomposition makes practical classification of explosives difficult. For

2015-438: The blast, suppress dust and noise, for fly rock prevention and sometimes to direct the blast. As a tunnel or excavation progresses the roof and side walls need to be supported to stop the rock falling into the excavation. The philosophy and methods for rock support vary widely but typical rock support systems can include: Typically a rock support system would include a number of these support methods, each intended to undertake

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2080-479: The capacity of an explosive to be initiated into detonation in a sustained manner. It is defined by the power of the detonator which is certain to prime the explosive to a sustained and continuous detonation. Reference is made to the Sellier-Bellot scale that consists of a series of 10 detonators, from n. 1 to n. 10 , each of which corresponds to an increasing charge weight. In practice, most of

2145-425: The choice being determined by the characteristics of the explosive. Dependent upon the method employed, an average density of the loaded charge can be obtained that is within 80–99% of the theoretical maximum density of the explosive. High load density can reduce sensitivity by making the mass more resistant to internal friction . However, if density is increased to the extent that individual crystals are crushed,

2210-632: The construction of Hambley Boulevard atop the former railbed – a lasting tribute to William Hambley. These two phases created an additional 150 acres (0.61 km) of downtown property at a cost of $ 19,700,000. The project was dedicated on October 2, 1987. 37°28′31″N 82°32′20″W  /  37.47527°N 82.53891°W  / 37.47527; -82.53891 Rock cut Drilling and blasting currently utilizes many different varieties of explosives with different compositions and performance properties. Higher velocity explosives are used for relatively hard rock in order to shatter and break

2275-581: The construction of the Pikeville Cut-Through. It was also decided to relocate the Levisa Fork of the Big Sandy River, which then snaked through the downtown area, to eliminate almost-yearly flooding. The river bed then was to be reclaimed, significantly increasing the available space for development within the city. The project was constructed in four phases by the U.S. Army Corps of Engineers between November 26, 1973, and October 2, 1987. Phase I of construction began on November 26, 1973. By

2340-402: The cut, the river was rerouted, and the former riverbed filled. 5,000,000 cubic yards (3,800,000 m) of soil was moved to create 240 acres (0.97 km) of available land in downtown at a cost of $ 22,200,000. Phase III and IV of the construction began on March 15, 1983. The final stages consisted of: the construction of the downtown interchanges and flood walls , another new bridge, and

2405-421: The development of pressure within rounds of ammunition and separation of mixtures into their constituents. Volatility affects the chemical composition of the explosive such that a marked reduction in stability may occur, which results in an increase in the danger of handling. The introduction of water into an explosive is highly undesirable since it reduces the sensitivity, strength, and velocity of detonation of

2470-503: The dust that came from the coal hauling trains that passed through the city daily. In 1963, Pikeville received a $ 38,000 federal grant for a railroad relocation feasibility study and was named a Model City by the recently formed Model Cities Agency, generating even more funding. By 1965, his plan had further developed to accommodate Corridor B of the Appalachian Development Highway System , assuring

2535-401: The end of Phase I, nearly 13,000,000 cubic yards (9,900,000 m) of rock were blasted from Peach Orchard Mountain to create a channel for the road, railroad, and river. The cost of Phase I at completion was $ 17,250,000. Phase II of construction began on March 4, 1980. During this phase the coal tipples and railroad tracks were removed from downtown Pikeville, a bridge was constructed across

2600-498: The energy of the detonation. Once detonated, the nitrogen portion of the explosive formulation emerges as nitrogen gas and toxic nitric oxides . The chemical decomposition of an explosive may take years, days, hours, or a fraction of a second. The slower processes of decomposition take place in storage and are of interest only from a stability standpoint. Of more interest are the other two rapid forms besides decomposition: deflagration and detonation. In deflagration, decomposition of

2665-604: The energy released by those reactions. The gaseous products of complete reaction are typically carbon dioxide , steam , and nitrogen . Gaseous volumes computed by the ideal gas law tend to be too large at high pressures characteristic of explosions. Ultimate volume expansion may be estimated at three orders of magnitude, or one liter per gram of explosive. Explosives with an oxygen deficit will generate soot or gases like carbon monoxide and hydrogen , which may react with surrounding materials such as atmospheric oxygen . Attempts to obtain more precise volume estimates must consider

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2730-445: The explosive material is propagated by a flame front which moves relatively slowly through the explosive material, i.e. at speeds less than the speed of sound within the substance (which is usually still higher than 340 m/s or 1,220 km/h in most liquid or solid materials) in contrast to detonation, which occurs at speeds greater than the speed of sound. Deflagration is a characteristic of low explosive material. This term

2795-651: The explosive material, but a practical explosive will often include small percentages of other substances. For example, dynamite is a mixture of highly sensitive nitroglycerin with sawdust , powdered silica , or most commonly diatomaceous earth , which act as stabilizers. Plastics and polymers may be added to bind powders of explosive compounds; waxes may be incorporated to make them safer to handle; aluminium powder may be introduced to increase total energy and blast effects. Explosive compounds are also often "alloyed": HMX or RDX powders may be mixed (typically by melt-casting) with TNT to form Octol or Cyclotol . An oxidizer

2860-442: The explosive may become more sensitive. Increased load density also permits the use of more explosive, thereby increasing the power of the warhead . It is possible to compress an explosive beyond a point of sensitivity, known also as dead-pressing , in which the material is no longer capable of being reliably initiated, if at all. Volatility is the readiness with which a substance vaporizes . Excessive volatility often results in

2925-414: The explosive properties of two or more compounds; it is important to examine the data from several such tests (sand crush, trauzl , and so forth) in order to gauge relative brisance. True values for comparison require field experiments. Density of loading refers to the mass of an explosive per unit volume. Several methods of loading are available, including pellet loading, cast loading, and press loading,

2990-409: The explosive. Hygroscopicity is a measure of a material's moisture-absorbing tendencies. Moisture affects explosives adversely by acting as an inert material that absorbs heat when vaporized, and by acting as a solvent medium that can cause undesired chemical reactions. Sensitivity, strength, and velocity of detonation are reduced by inert materials that reduce the continuity of the explosive mass. When

3055-429: The explosives on the market today are sensitive to an n. 8 detonator, where the charge corresponds to 2 grams of mercury fulminate . The velocity with which the reaction process propagates in the mass of the explosive. Most commercial mining explosives have detonation velocities ranging from 1,800 m/s to 8,000 m/s. Today, velocity of detonation can be measured with accuracy. Together with density it

3120-413: The first time in warfare. The Chinese would incorporate explosives fired from bamboo or bronze tubes known as bamboo firecrackers. The Chinese also inserted live rats inside the bamboo firecrackers; when fired toward the enemy, the flaming rats created great psychological ramifications—scaring enemy soldiers away and causing cavalry units to go wild. The first useful explosive stronger than black powder

3185-516: The ground. The use of explosives in mining goes back to the year 1627, when gunpowder was first used in place of mechanical tools in the Hungarian (now Slovak ) town of Banská Štiavnica . The innovation spread quickly throughout Europe and the Americas. The standard method for blasting rocks was to drill a hole to a considerable depth and deposit a charge of gunpowder at the further end of

3250-494: The highest per capita explosives consumption that year with 45 m per capita. As the name suggests, drilling and blasting works as follows: The positions and depths of the holes (and the amount of explosive each hole receives) are determined by a carefully constructed pattern, which, together with the correct timing of the individual explosions, will guarantee that the tunnel will have an approximately circular cross-section. During operation, blasting mats may be used to contain

3315-532: The history of chemical explosives lies in the history of gunpowder . During the Tang dynasty in the 9th century, Taoist Chinese alchemists were eagerly trying to find the elixir of immortality. In the process, they stumbled upon the explosive invention of black powder made from coal, saltpeter, and sulfur in 1044. Gunpowder was the first form of chemical explosives and by 1161, the Chinese were using explosives for

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3380-428: The hole and then fill the remainder of the hole with clay or some other soft mineral substance, well rammed, to make it as tight as possible. A wire laid in the hole during this process was then removed and replaced with a train of gunpowder. This train was ignited by a slow match , often consisting simply of brown paper smeared with grease, intended to burn long enough to allow the person who fires it enough time to reach

3445-623: The largest civil engineering projects in the Western Hemisphere . Nearly 18,000,000 cubic yards (14,000,000 m) of soil and rock were moved, making the Pikeville Cut-Through second only to the Panama Canal (240,000,000 cubic yards (180,000,000 m)) when ranking the hemisphere's largest earth-moving projects. Dr. William Hambley , who served as mayor of Pikeville for 29 years, Robert H. Holcomb , Chamber of Commerce president, and Henry Stratton , local attorney, spearheaded

3510-450: The manufacturing operations. A primary explosive is an explosive that is extremely sensitive to stimuli such as impact , friction , heat , static electricity , or electromagnetic radiation . Some primary explosives are also known as contact explosives . A relatively small amount of energy is required for initiation . As a very general rule, primary explosives are considered to be those compounds that are more sensitive than PETN . As

3575-436: The moisture content evaporates during detonation, cooling occurs, which reduces the temperature of reaction. Stability is also affected by the presence of moisture since moisture promotes decomposition of the explosive and, in addition, causes corrosion of the explosive's metal container. Explosives considerably differ from one another as to their behavior in the presence of water. Gelatin dynamites containing nitroglycerine have

3640-443: The molecule is said to have a zero oxygen balance. The molecule is said to have a positive oxygen balance if it contains more oxygen than is needed and a negative oxygen balance if it contains less oxygen than is needed. The sensitivity, strength , and brisance of an explosive are all somewhat dependent upon oxygen balance and tend to approach their maxima as oxygen balance approaches zero. A chemical explosive may consist of either

3705-457: The more important characteristics are listed below: Sensitivity refers to the ease with which an explosive can be ignited or detonated, i.e., the amount and intensity of shock , friction , or heat that is required. When the term sensitivity is used, care must be taken to clarify what kind of sensitivity is under discussion. The relative sensitivity of a given explosive to impact may vary greatly from its sensitivity to friction or heat. Some of

3770-410: The possibility of such side reactions, condensation of steam, and aqueous solubility of gases like carbon dioxide. Oxygen balance is an expression that is used to indicate the degree to which an explosive can be oxidized. If an explosive molecule contains just enough oxygen to convert all of its carbon to carbon dioxide, all of its hydrogen to water, and all of its metal to metal oxide with no excess,

3835-421: The project. The Pikeville Cut-Through is 1,300 feet (400 m) wide, 3,700 feet (1.1 km) long, and 523 feet (159 m) deep. The project was completed in 1987 following 14 years of work at a cost of $ 77.6 million ($ 208 million in 2023 dollars). The project was initially envisioned by Pikeville native Dr. William Hambley in 1960. He wanted to relocate the railbed because he wanted to eliminate

3900-453: The rock, while low velocity explosives are used in soft rocks to generate more gas pressure and a greater heaving effect. For instance, an early 20th-century blasting manual compared the effects of black powder to that of a wedge, and dynamite to that of a hammer. The most commonly used explosives in mining today are ANFO based blends due to lower cost than dynamite . Before the advent of tunnel boring machines (TBMs), drilling and blasting

3965-492: The sum of the masses of the two initial layers. There are applications where a shock wave, and electrostatics, can result in high velocity projectiles such as in an electrostatic particle accelerator . An explosion is a type of spontaneous chemical reaction that, once initiated, is driven by both a large exothermic change (great release of heat) and a large positive entropy change (great quantities of gases are released) in going from reactants to products, thereby constituting

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4030-499: The test methods used to determine sensitivity relate to: Specific explosives (usually but not always highly sensitive on one or more of the three above axes) may be idiosyncratically sensitive to such factors as pressure drop, acceleration, the presence of sharp edges or rough surfaces, incompatible materials, or even —  in rare cases —  nuclear or electromagnetic radiation. These factors present special hazards that may rule out any practical utility. Sensitivity

4095-425: The two layers. As the length of time the shock wave spends at any point is small, we can see mixing of the two metals and their surface chemistries, through some fraction of the depth, and they tend to be mixed in some way. It is possible that some fraction of the surface material from either layer eventually gets ejected when the end of material is reached. Hence, the mass of the now "welded" bilayer, may be less than

4160-799: Was nitroglycerin , developed in 1847. Since nitroglycerin is a liquid and highly unstable, it was replaced by nitrocellulose , trinitrotoluene ( TNT ) in 1863, smokeless powder , dynamite in 1867 and gelignite (the latter two being sophisticated stabilized preparations of nitroglycerin rather than chemical alternatives, both invented by Alfred Nobel ). World War I saw the adoption of TNT in artillery shells. World War II saw extensive use of new explosives (see: List of explosives used during World War II ) . In turn, these have largely been replaced by more powerful explosives such as C-4 and PETN . However, C-4 and PETN react with metal and catch fire easily, yet unlike TNT, C-4 and PETN are waterproof and malleable. The largest commercial application of explosives

4225-509: Was the only economical way of excavating long tunnels through hard rock, where digging is not possible. Even today, the method is still used in the construction of tunnels, such as in the construction of the Lötschberg Base Tunnel . The decision whether to construct a tunnel using a TBM or using a drill and blast method includes a number of factors. Tunnel length is a key issue that needs to be addressed because large TBMs for

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