壁

Wall — Grokipedia Fact-checked by Grok 3 months ago Wall Ara Eve Leo Sal 1x A wall is a vertical structure, typically constructed from materials such as brick , stone , concrete , or other durable substances, that serves as a physical barrier to divide, enclose, or support spaces in buildings and other constructions. [1] [2] Walls provide essential functions including structural support , protection from external elements and threats, and delineation of territories, with evidence of their use dating back to ancient civilizations such as Sumerian fortified barriers constructed around 21st century B.C. to defend against nomadic incursions. [3] [4] In engineering and architecture , walls are classified primarily as load-bearing, which transfer structural loads to the foundation, or non-load-bearing, which primarily partition interiors without supporting weight from above. [5] [6] Historically, walls have been pivotal in human society for security and separation, often proving effective in impeding unauthorized movement when properly designed and maintained, as seen in defensive structures that shaped geopolitical boundaries and urban development. [7] [8] Etymology and Definition Etymology The English term "wall" originates from Old English weall , attested around the 9th century, initially referring to a rampart, dike, earthwork, dam , or natural barrier such as a rocky shore or cliff. [9] [10] This word was borrowed into Proto-West Germanic wall from Latin vallum , a term for an earthen rampart or defensive embankment reinforced by a palisade of stakes, dating to classical Latin usage in military contexts. [9] [11] The Latin vallum derives collectively from vallus ("stake" or " palisade "), whose precise root remains uncertain but may connect to Proto-Indo-European notions of turning or rolling, as in enclosing or hedging materials. [9] In broader linguistic evolution, the concept of a wall shifted from denoting natural enclosures or rudimentary fortifications to engineered vertical structures for bounding spaces, reflecting adaptations in construction techniques across Indo-European languages . Germanic cognates like Middle High German wall preserved the borrowed form, while Romance languages drew from Latin mūrus ("masonry wall"), traced to Proto-Indo-European meh₂y- ("to bind" or "fix"), emphasizing solidity and permanence. [12] Outside Indo-European families, Semitic languages feature terms like Hebrew ḥomāh (חומה), a feminine form implying a joined or protective barrier, rooted in an unused verb for surrounding or uniting elements, often applied to fortified enclosures in biblical texts. [13] Core Definition and Functions A wall is a vertical, rigid structure typically constructed from solid materials such as stone, brick, concrete, or masonry, serving as a physical barrier to define, enclose, or divide spaces. [1] Unlike fences, which often incorporate gaps or permeable elements for visibility or ventilation, walls are generally continuous and solid, providing an impermeable division without intentional openings. [14] This distinguishes walls from temporary barriers, which lack permanence and structural integrity, emphasizing walls' role as enduring, load-capable elements in construction. [2] The primary functions of walls include spatial separation and structural support . Walls delineate boundaries between rooms or properties, preventing passage and ensuring privacy or controlled access. [15] Load-bearing walls transfer vertical forces from roofs, floors, and upper stories to the foundation, maintaining building stability through compressive strength . [16] Walls also provide environmental protection and deterrence. They shield interiors from external elements like wind, rain, and temperature fluctuations via thermal insulation and weather resistance, while reducing sound transmission for acoustic isolation. [1] In security contexts, a wall's mass and height impede unauthorized movement by exploiting physical principles of inertia and gravitational potential , thereby altering potential intruder behavior through increased effort required for breach. [1] Historical Development Ancient Walls (Pre-500 AD) The oldest known fortified settlement walls were constructed at Jericho in the Pre-Pottery Neolithic A period, dating to approximately 8000 BC, consisting of mudbrick and stone structures up to 4 meters high and 1.8 meters thick, surrounding an area of about 4 hectares. [17] These walls, including an adjacent 8.5-meter-tall tower, likely served to protect early agricultural communities from human or animal threats, enabling the storage of surplus crops and supporting a population estimated at 2,000–3,000 residents, which represented a significant demographic concentration for the era. [17] Archaeological evidence from stratified layers indicates multiple rebuilds over centuries, correlating with the site's role as a proto-urban center in the Jordan Valley , where walls facilitated sedentary farming amid regional instability. [18] In Mesopotamia , the Sumerian ruler Shulgi of Ur commissioned the first documented linear border wall around 2100 BC, stretching 250 kilometers between the Tigris and Euphrates rivers to impede Amorite nomadic incursions into settled territories. [19] This earthen and reed-reinforced barrier, patrolled by garrisons, aimed at territorial control and raid prevention, as evidenced by cuneiform inscriptions detailing its construction and maintenance costs in labor and resources; post-erection records show stabilized southern frontiers, reducing documented migrations and enabling agricultural intensification in core Sumerian heartlands. [20] Similar enclosures appeared in the Indus Valley Civilization by 2600 BC, with cities like Mohenjo-Daro and Harappa featuring massive baked-brick walls up to 12 meters high, designed for urban security and flood mitigation along riverine floodplains, which sustained populations exceeding 40,000 through protected granaries and irrigation systems. [21] Ancient Egyptian hydraulic walls, such as groin structures along the Nile dating from the Old Kingdom (c. 2686–2181 BC), extended up to 200 meters in length and 5 meters thick, channeling floodwaters to safeguard agricultural fields and settlements from inundation while deterring irregular threats. [22] In China , during the Warring States period (475–221 BC), states like Qin and Zhao erected initial rammed-earth segments totaling thousands of kilometers to defend agrarian lowlands against northern nomadic horsemen, incorporating watchtowers and moats for early warning. [23] The Roman Servian Wall , built in 378 BC of volcanic tuff and concrete , enclosed 426 hectares with a height of 10 meters and width of 4 meters, responding to the Gallic sack of 390 BC by fortifying the city's seven hills and supporting a growing urban populace through enhanced perimeter defense. [24] Across these examples, walls empirically correlated with reduced raid frequencies in archaeological settlement patterns—such as fewer destruction layers post-construction—and demographic booms, as protected perimeters allowed surplus production and population densities unattainable in open nomadic-vulnerable landscapes. [20] [23] Medieval and Early Modern Walls (500-1800 AD) Following the fragmentation of the Western Roman Empire after 476 AD, medieval Europe saw widespread reconstruction and expansion of urban walls to defend against barbarian incursions, including Vikings in the 9th-10th centuries, Magyar raids until their settlement around 955 AD, and Muslim advances during the Reconquista. These fortifications, often built from local stone with battlements, towers, and gates, emphasized layered defenses such as moats and barbicans to counter siege tactics like battering rams and scaling ladders. In Spain, the walls of Ávila, erected primarily between 1090 and 1099 under Alfonso VI with later additions up to the 14th century, enclosed 33 hectares with a 2,516-meter perimeter, 87 semicircular towers averaging 10 meters high, and nine gates, providing effective protection against Moorish forces and enabling the city's role as a frontier stronghold. [25] [26] The Theodosian Walls of Constantinople, originally constructed in 408-413 AD but maintained and repaired through the medieval era, exemplified advanced engineering with double land walls, a moat , and 96 towers, repelling at least 20 major siege s including Arab attempts in 674-678 and 717-718 AD, Bulgar assaults in 813 and 860 AD, and the Fourth Crusade's naval breach in 1204 before restoration. These walls preserved the Byzantine Empire's core territories, with historical accounts noting their role in withstanding prolonged bombardments until Ottoman gunpowder artillery overwhelmed weakened sections during the 53-day siege ending May 29, 1453. Walled European cities facilitated economic expansion by securing merchant activities and concentrating populations; for example, fortifications correlated with urban growth during the 11th-13th centuries' Commercial Revolution , where protected trade hubs like those in Italy and the Low Countries saw population densities rise to 20-50 persons per hectare inside walls versus rural vulnerabilities to plunder, fostering guilds and markets. [27] [28] [29] In East Asia , the Ming Dynasty (1368-1644 AD) rebuilt and extended the Great Wall system to over 5,500 miles of primary fortifications, incorporating brick-faced earthen barriers, watchtowers, and garrisons to counter northern nomadic threats, particularly Mongol remnants after the Yuan Dynasty's fall in 1368. Imperial records document the walls' deterrence of routine raids, with construction peaks under emperors like Yongle (1402-1424) correlating to fewer reported breaches compared to pre-Ming eras; for instance, while earlier walls failed against Genghis Khan's 1211-1234 invasions due to incomplete coverage, Ming enhancements included 25,000 watchtowers and forced labor of over 1 millio