An earthquake is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earths lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to people around. The seismicity or seismic activity of an area refers to the frequency, Earthquakes are measured using measurements from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe and these two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly imperceptible or weak and magnitude 7 and over potentially cause damage over larger areas. The largest earthquakes in historic times have been of magnitude slightly over 9, intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the damage to structures it causes. At the Earths surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground, when the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami.
Earthquakes can trigger landslides, and occasionally volcanic activity, in its most general sense, the word earthquake is used to describe any seismic event — whether natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of faults, but by other events such as volcanic activity, mine blasts. An earthquakes point of rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter, tectonic earthquakes occur anywhere in the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. The sides of a fault move past each other smoothly and aseismically only if there are no irregularities or asperities along the surface that increase the frictional resistance. Most fault surfaces do have such asperities and this leads to a form of stick-slip behavior, once the fault has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface.
This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the portion of the fault. This energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface and this process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the elastic-rebound theory. It is estimated that only 10 percent or less of a total energy is radiated as seismic energy. Most of the energy is used to power the earthquake fracture growth or is converted into heat generated by friction
A rock bolt is a long anchor bolt, for stabilizing rock excavations, which may be used in tunnels or rock cuts. It transfers load from the exterior to the confined interior of the rock mass. Rock bolts were first used in mining in the 1890s, with systematic use documented at the St Joseph Lead Mine in the U. S. in the 1920s. Rock bolts were applied to civil tunneling support in the U. S. as shown in the figure, rock bolts are almost always installed in a pattern, the design of which depends on the rock quality designation and the type of excavation. Rock bolts are a component of the New Austrian Tunneling method. As with anchor bolts, there are many proprietary rock bolt designs, there are fiberglass bolts which can be cut through again by subsequent excavation. Many papers have written on methods of rock bolt design. Rock bolts work by knitting the rock mass together sufficiently before it can move enough to loosen, as in the photo, rock bolts may be used to support wire mesh, but this is usually a small part of their function.
Unlike common anchor bolts, rock bolts can become seized throughout their length by small shears in the rock mass, so they are not fully dependent on their pull-out strength. This has become an item of controversy in the Big Dig project, rock bolts can be used to prevent rockfall
Highways in Greece
Highways in Greece are generally organized so that the odd numbered highways are of north-south alignment and even numbered highways are of east-west alignment. The designation of some important roads of Greece as national was decided by a 1955 decree, in 1998, a survey of the Hellenic Statistical Authority defined some new national roads that were constructed after the 1963 decision. Furthermore, motorway numbers in Greece are different and irrelevant to other highways numbers, for example, Motorway 6 refers to the Attiki Odos motorway, while GR-6 refers to a different road. Greeces motorway network has been extensively modernised throughout the 2000s and part of it is still under construction, most of it is expected to be completed by early 2017. There are a total of 10 main routes throughout the Greek mainland and Crete, from which some feature numerous branches/auxiliary routes, most of the route has been upgraded to motorway standards, expept for 25 kilometres through the Tempe Valley.
As of summer 2008, works were in progress around the Malian Gulf, most of the route around the bay, was completed in April 2008, but due to delays, the last part was finally given to traffic on March 16,2015. At Tempe valley, works started in 2008, in order to be completed around 2012 and this part will include 11 km of tunnels, made mostly for environmental protection and, of course, road safety. Furthermore, the section between Thessaloniki and Evzoni, is yet to be converted into motorway, but this is not planned to happen in the near future. The full length of motorway is around 553 km or 346 miles. Note that until recently, the P in PAThE referred to Patras, Motorway 11 is a branch of the A1, connecting it with the city of Chalcis. Motorway 12 is another branch of the A1, connecting it with the city of Volos, although it is a dual carriageway throughout its length, parts of it remain with traffic lights and not all sections of the branch are up to motorway standards. Ongoing construction has been happening to upgrade it to such and it includes a tunnel near the village of Goritsa.
Motorway 13 is a branch of the A1, from Thiva to Elefsina, connecting it with the Olympia Odos motorway. Motorway 2, colloquially referred to as the Egnatia Odos, is a new motorway starting at the port of Igoumenitsa, there are auxiliary routes to Albania and Bulgaria, with the main route leading to Turkey. The Republic of Macedonia is accessed through the A1, as described above, another auxiliary route runs close to the Evros river in the prefecture of the same name, reaching a point where Greeces and Bulgarias borders meet. Some of those routes are not motorways, but typical 2-lane highways. The project, was completed in 2009, with the length of the route being 670 kilometres or 416 miles. As it passes through the eastern periphery of Thessaloniki the A25 becomes part of the Thessaloniki Inner Ring Road, Motorway 27 is another branch of the A2, at Kozani which leads towards Ptolemaida and from there to Florina and the border crossing with the Republic of Macedonia
Roads in the United Kingdom
Roads in the United Kingdom form a network of varied quality and capacity. Road distances are shown in miles or yards and UK speed limits are indicated in miles per hour or by the use of the speed limit symbol. Some vehicle categories have various lower maximum limits enforced by speed limiters, enforcement of UK road speed limits increasingly uses speed guns, automated in-vehicle systems and automated roadside traffic cameras. A unified numbering system is in place for Great Britain, whilst in Northern Ireland, the earliest specifically engineered roads were built during the British Iron Age. The road network was expanded during the Roman occupation, some of these survive and others were lost. New roads were added in the Middle Ages and from the 17th century onwards, certain aspects of the legal framework remain under the competence of the United Kingdom parliament. Although some roads have much older origins, the network was subject to development from the 1950s to the mid-1990s. From then, construction of roads has become controversial with direct action campaigns by environmentalists in opposition.
In the UK, vehicles drive on the left and on multi-lane carriageways drivers are expected to keep to the left lane except when overtaking, in Great Britain, the Highway Code applies to drivers. In Northern Ireland, the Highway Code for Northern Ireland applies, UK speed limits are shown in mph. With a few exceptions, they are in multiples of 10, unless a lower speed limit is posted on a road, the national speed limit applies, which varies between class of vehicles and the type of road. In a built-up area, unless signs indicate otherwise, a limit of 30 miles per hour applies, other limits are shown in the table. For a road to be classed as a carriageway, the two directions of traffic flow must be physically separated by a central reservation. Roads in the UK are classified as M, A, or B roads, as well as categories of more minor roads, for internal purposes. These numbers follow a zonal system, there is no available explanation for the allocation of road numbers in Northern Ireland. The majority of the major routes are motorways, and are designed to carry long distance traffic.
The next category is the A roads, which form the route network. A primary route is defined as, primary destinations are usually cities and large towns, to which, as a result of their size, a high volume of traffic is expected to go
Shotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique. It is reinforced by steel rods, steel mesh, and/or fibers. Fiber reinforcement is used for stabilization in applications such as slopes or tunneling. Shotcrete is usually a term for both the wet-mix and dry-mix versions. In pool construction, the term refers to wet-mix. In this context, these terms are not interchangeable, Shotcrete is placed and compacted at the same time, due to the force with the nozzle. It can be sprayed onto any type or shape of surface, known as gunite, was invented in 1907 by American taxidermist Carl Akeley to repair the crumbling facade of the Field Columbian Museum in Chicago. He used the method of blowing dry material out of a hose with compressed air, in 1911, he was granted a patent for his inventions, the cement gun, the equipment used, and gunite, the material that was produced. There is no evidence that Akeley ever used sprayable concrete in his taxidermy work, F.
Trubee Davison covered this and other Akeley inventions in a special issue of Natural History magazine. Until the 1950s when the process was devised, only the dry-mix process was used. In the 1960s, the method for gunning by the dry method was devised with the development of the rotary gun. Shotcrete is a means and method for placing structural concrete. The nozzleman is the controlling the nozzle that delivers the concrete to the surface. The nozzle is controlled by hand on small jobs, for example the construction of small swimming pools, on larger work the nozzle can sometimes be held by mechanical arms where the nozzleman controls the operation by a hand-held remote control. The dry mix method involves placing the dry ingredients into a hopper, the nozzleman controls the addition of water at the nozzle. The water and the dry mixture is not completely mixed, but is completed as the hits the receiving surface. This requires a skilled nozzleman, especially in the case of thick or heavily reinforced sections, the dry mix process is useful in repair applications when it is necessary to stop frequently, as the dry material is easily discharged from the hose.
Wet-mix shotcrete involves pumping of a previously prepared concrete, typically ready-mixed concrete, compressed air is introduced at the nozzle to impel the mixture onto the receiving surface
Roads in Portugal
Roads in Portugal are defined by National Road Plan, which describes the existing and planned network of Portuguese roads. The present plan in force is the 2000 National Road Plan and it has replaced the previous PRN1985, which itself had replaced the PRN1945. The Portuguese road infrastructure is considered the best in Europe and the second best in the World by the World Economic Forum in its Global Competitiveness Report for 2014–2015. The scenic road between Peso da Régua and Pinhão, in Northern Portugal, was considered the World Best Driving Road and this road is a section of the N222 which route follows the Douro Valley. The precognized network was classified in 1850 as estradas and caminhos, with the estradas being classified as 1st, caminhos were routes of mere local interest. In 1862, the roads were classified as 1st class roads or estradas reais, 2nd class roads or estradas distritais, the estradas reais were those with direct or indirect origin in Lisbon) and the estradas municipais were those managed by the municipalities.
With the abolition of the Monarchy in 1910, the estradas reais were renamed estradas nacionais, in 1913, the Law of 22 February establishes a commission to study the new classification of the roads and presents the guidelines to proceed to that classification. However, The new classification and road plan would only be established 13 years later, both the 1st and 2nd class roads would be designated estradas nacionais, with the term estrada distrital disappearing. They would be designated EN xx-x, in a way that the number before the - designated the number of the road and this plan established 23 roads of 1st class and 112 roads of 2nd class. The General Plan of National Roads would be reviewed and definitely approved by the Decree nº16075 of 30 September 1928. The preliminary report was clear to state that from the 16000 km of the road network,4000 km were to be completed. The roads were reclassified as estradas nacionais, estradas municipais and caminhos públicos, in 1933, the whole network totalized 16900 km.
By that date, the National and Municipal network, comprised 20500 km, branch roads, emerging from a determinated road, which was identified in the X factor, with a number of order according to point of origin, identified in the Y factor. The road with most branch roads was N1, originally with 16 roads, the National Roads Statutes were subsequently approved in 1949. The first urban highways have been in the 1960s. The road classes where identified by colour codes, red for 1st class, blue for 2nd class, green for 3rd class, yellow for municipal roads and these colors were applied in the bases of the location markers and occasionally in the background of the road numbers. The numbering distribution for main roads was according to the importance of its route in the network, and for N101 and over were numbered in a North to South growing fashion. The extension of the roads had no relation with its class, with existing 3rd class roads more than 100 km long, the longest road of the 1945 Plan was N2, connecting Chaves to Faro, extending for 738 km
Types of mass wasting include creep, flows and falls, each with its own characteristic features, and taking place over timescales from seconds to years. Mass wasting occurs on both terrestrial and submarine slopes, and has observed on Earth, Venus. When the gravitational force acting on a slope exceeds its resisting force, the slope materials strength and cohesion and the amount of internal friction between material help maintain the slopes stability and are known collectively as the slopes shear strength. The steepest angle that a slope can maintain without losing its stability is known as its angle of repose. When a slope made of loose material possesses this angle, its shear strength perfectly counterbalances the force of gravity acting upon it. Mass wasting may occur at a slow rate, particularly in areas that are very dry or those areas that receive sufficient rainfall such that vegetation has stabilized the surface. It may occur at high speed, such as in rockslides or landslides, with disastrous consequences.
Factors that change the potential of mass wasting include, change in angle, weakening of material by weathering, increased water content, changes in vegetation cover. Volcano flanks can become over-steep resulting in instability and mass wasting and this is now a recognised part of the growth of all active volcanoes. The failure of the flank of Mount St Helens in 1980 showed how rapidly volcanic flanks can deform. Water can increase or decrease the stability of a slope depending on the amount present, small amounts of water can strengthen soils because the surface tension of water increases soil cohesion. This allows the soil to resist erosion better than if it were dry, if too much water is present the water may act to increase the pore pressure, reducing friction, and accelerating the erosion process and resulting in different types of mass wasting. A good example of this is to think of a sand castle, water must be mixed with sand in order for the castle to keep its shape. If too much water is added the sand away, if not enough water is added the sand falls.
Water increases the mass of the soil, this is important because an increase in mass means that there will be an increase in velocity if mass wasting is triggered. Types of mass movement are distinguished based on how the soil, soil creep is a long term process. The combination of movements of soil or rock in different directions over time are directed by gravity gradually downslope. The steeper the slope, the faster the creep, the creep makes trees and shrubs curve to maintain their perpendicularity, and they can trigger landslides if they lose their root footing
Where highway ramps between express and local/collector lanes cross over another this is commonly known as braided ramps. Given the considerable overall width of this design, new suburban freeways are often designed with interchanges spaced far apart to avoid the need for parallel roadways. Ontario, Gardiner Expressway from Wickman Road to Royal York Road, Highway 400 in York Region, from the Highway 7 interchange to south of Langstaff Road. Ontario, Highway 401 in Peel Region and Durham Region, from Hurontario Street to Highway 427. From east of Kipling Avenue—serving the interchange with Highway 409—to west of Brock Road, Highway 404 traffic from westbound 401 and eastbound 401 has a brief collector-express separation and ends just north of Sheppard Avenue East. Ontario, Highway 403 from the Highway 401/410 interchange to Cawthra Road, Highway 427 from Queen Elizabeth Way/Gardiner Expressway to Highway 401 in Toronto. Ontario, Conestoga Parkway from Lancaster Street to Krug Street in Kitchener, Autoroute 40 in Repentigny, Quebec.
From Larochelle Blvd to Industrial Blvd, from Route 341 to Route 343. Nova Scotia, Nova Scotia Highway 118, in Dartmouth, Nova Scotia, State Route 180 at the State Route 41 and the State Route 168 interchanges. This interchange is unusual because it allows traffic to flow between State Route 41 and State Route 168, bypassing the State Route 180 main line. Google Maps California, Interstate 5 at the El Toro Y in Irvine, Interstate 10 west of downtown Los Angeles from the Harbor Freeway to Arlington Avenue. California, Interstate 805 in Chula Vista, between the H Street and E Street/Bonita Road exits, from Interstate 280 to Julian Street along Downtown San Jose. Southbound, from Interstate 280 to Alma Avenue, California, U. S. Route 101 near San Francisco International Airport Florida, I-110 in Pensacola becomes a controlled-access freeway between the Airport Blvd and the Bayou Blvd exits. Georgia, I-85 in Atlanta, old HOV lane became express lane in 2011,16 miles between Exit 94 and Exit 109. Illinois, The Dan Ryan Expressway and Kennedy Expressway, between 71st Street and Interstate 55, and between Ohio Street and the Edens and it is not a freeway, instead it is called a junior expressway.
Grade-level intersections require vehicles to execute left hook turns from the local lanes. Illinois, Illinois Route 53 between Interstate 290 at its end and Kirchhoff Road follows a local-express format. Indiana, The Borman Expressway in Gary, The I-65/I-70 junction in Indianapolis
A controlled-access highway is a type of highway which has been designed for high-speed vehicular traffic, with all traffic flow and ingress/egress regulated. Common English terms are freeway and expressway, other similar terms include Interstate and parkway. Some of which may be limited-access highways, although this term can refer to a class of highway with somewhat less isolation from other traffic. In countries following Vienna convention, the motorway qualification implies they are forbidden for walking or parking, a controlled-access highway provides an unhindered flow of traffic, with no traffic signals, intersections or property access. They are free of any at-grade crossings with roads, railways, or pedestrian paths. Entrances and exits to the highway are provided at interchanges by slip roads, on the controlled-access highway, opposing directions of travel are generally separated by a median strip or central reservation containing a traffic barrier or grass. Elimination of conflicts with other directions of traffic dramatically improves safety and capacity, controlled-access highways evolved during the first half of the 20th century.
Italy opened its first autostrada in 1924 connecting Milan to Varese, Germany began to build its first 30-kilometre autobahn controlled-access highway without speed limits in 1932 between Cologne and Bonn. It rapidly constructed a system of such roads in anticipation of their use in the Second World War. The first North American freeways opened in the New York City area in the 1920s, heavily influenced by the railways, did not build its first motorway, the Preston By-pass, until 1958. Most technologically advanced nations feature a network of freeways or motorways to provide high-capacity urban travel, or high-speed rural travel. Many have a national-level or even international-level system of route numbering, exit is marked with another symbol. The definitions of motorway from the OECD and PIARC are almost identical, british Standards Motorway, Limited-access dual carriageway road, not crossed on the same level by other traffic lanes, for the exclusive use of certain classes of motor vehicle.
ITE Freeway, A divided major roadway with full control of access and this definition applies to toll as well as toll-free roads. Freeway A, This designates roadways with greater complexity and high traffic volumes. Usually this type of freeway will be found in areas in or near the central core. Freeway B, This designates all other divided roadways with full control of access where lighting is needed, principal arterials may cross through urban areas, serving suburban movements. The traffic is characterized by high speeds and full or partial access control, other roads leading to a principal arterial are connected to it through side collector roads
Expressways of China
The expressway network of China is an integrated system of national and provincial-level expressways in China. It is the worlds largest expressway system by length, having surpassed the length of the American Interstate Highway System in 2011. Between the end of 2014 and 2015, the length of the network grew from 111,950 kilometres to 123,000 kilometres meaning 11,050 kilometres of expressway were built in 2015 alone. This backbone is known as the 71118 network, in addition, the provincial-level divisions of China each have their own expressway systems. Expressways in China are a recent addition to the transportation infrastructure in the country. Previously, the road network consisted of a system of at-grade China National Highways. Chinas first expressway, the Shanghai–Jiading Expressway, opened in October 1988 and this 17.37 kilometres expressway now forms part of Shanghais expressway network. The early 1990s saw the start of the countrys massive plan to upgrade its network of roads, in 1999, the length of the network exceeded 10,000 kilometres in length.
Many of the major expressways parallel routes of the older China National Highways, prior to the 1980s, freight and passenger transport activities were predominantly achieved by rail transport rather than by road. The 1980s and 1990s saw a trend toward roads as a method of transportation. In 1978, rail transport accounted for 54. 4% of the freight movement in China. By 1997, road transports share of freight movement had increased to 13. 8% while the railways share decreased to 34. 3%. Similarly, roads share of transport increased from 29. 9% to 53. 3% within the same time period. The shift from rail to road can be attributed to the development of the expressway network in China. On 7 June 1984, Chinas expressway ambitions began when construction of the Shenyang–Dalian Expressway began between the cities of Shenyang and Dalian, the expressway is now part of the longer G15 Shenyang–Haikou Expressway. Later that year, construction began on the Shanghai–Jiading Expressway in the city of Shanghai, the Shanghai–Jiading Expressway opened on 31 October 1988, becoming the first completed expressway in China.
This replaced the proposal for five north-south and seven east-west core routes. The total costs of the expressway network are estimated to be 2 trillion yuan
An avalanche is a rapid flow of snow down a sloping surface. Avalanches are typically triggered in a zone from a mechanical failure in the snowpack when the forces on the snow exceed its strength. After initiation, avalanches usually accelerate rapidly and grow in mass, if the avalanche moves fast enough some of the snow may mix with the air forming a powder snow avalanche, which is a type of gravity current. Slides of rocks or debris, behaving in a way to snow, are referred to as avalanches. The remainder of this article refers to snow avalanches, the load on the snowpack may be only due to gravity, in which case failure may result either from weakening in the snowpack or increased load due to precipitation. Avalanches that occur in this way are known as spontaneous avalanches, Avalanches can be triggered by other loads such as skiers, animals or explosives. Seismic activity may trigger the failure in the snowpack and avalanches. A popular myth is that avalanches can be triggered by loud noise or shouting, Avalanches are not rare or random events and are endemic to any mountain range that accumulates a standing snowpack.
Avalanches are most common during winter or spring but glacier movements may cause ice, there is no universally accepted classification of avalanches—different classifications are useful for different purposes. Avalanches can be described by their size, their potential, their initiation mechanism, their composition. Most avalanches occur spontaneously during storms under increased load due to snowfall, the second largest cause of natural avalanches is metamorphic changes in the snowpack such as melting due to solar radiation. Other natural causes include rain, earthquakes and icefall, artificial triggers of avalanches include skiers and controlled explosive work. Avalanche initiation can start at a point with only an amount of snow moving initially. A snowpack will fail when the load exceeds the strength, the load is straightforward, it is the weight of the snow. However, the strength of the snowpack is much more difficult to determine and is extremely heterogenous and it varies in detail with properties of the snow grains, density, temperature, water content, and the properties of the bonds between the grains.
These properties may all metamorphose in time according to the humidity, water vapour flux, temperature. The top of the snowpack is influenced by incoming radiation. One of the aims of research is to develop and validate computer models that can describe the evolution of the seasonal snowpack over time
Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties.
Rocks are geologically classified according to such as mineral and chemical composition, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic.
Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites