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1、According to the contents of this semester learning,construction engineering foundation is the most important part.The basis of design and construction quality are directly affect the safety, economy and rationality of buildings.From security to analyze,the quality of construction engineering founda2、tion makes huge impact on building security .There are many tilt or collapse of a building project examples because of base foundation of quality problems.From rationality to analyze,the reasonable choice of building foundation forms is the key to guarantee basic safety and economy.Foundation is oot3、 only one of the keys to guarantee the building safety and meets the requirement, but also it have sufficient strength and stability, and can resist the underground erosion of various kinds of factors.1.Review of Building FoundationBuilding Foundation is part of the vertical load-bearing elements of4、 buildings in direct contact with the fground support buildings.The soil that support the weight of the building is called the ground .The foundation status is not related to the upper part of the building,but also it is related to the lower part of the geological conditions.The foundation is based 5、on the first part of the building construction, which bear the load of the buildings upper portion, and these loads to pass the ground.From the force and angle of force transmission,due to the bearing capacity of soil per unit area is limited,the upper structure by the load to the ground, only to ex6、pand the foundation base area, also is to reduce the pressure on the bottom of foundation, to adapt to the requirement of ground stress,then it will adapt to the requirement of ground stress.However, due to the different materials used in the foundation, its force characteristics are different, ther7、efore, it is not the basis of any material produced can be unlimited expansion of its bottom surface area.2.Common Forms of Building FoundationThe determine of the form of infrastructure is certain by the upper structure, load size and ground soil conditions.In general,the upper structure directly a8、ffect the basic form,But when the upper load increase, and the foundation bearing capacity are changed, the basic form changed also.According to the foundations depth,the building foundation will be invided into shallow foundations and deep foundations.Shallow foundations:Buried d 3 5cm width or dep9、th of the bottom surface with the base b ratio d / b 3 5cm, usually set the foundation for a more specific method of construction is called a deep foundation.According to structure type,shallow foundations can be invided into strip foundation, independent foundation, raft foundation.2.1 Strip Founda10、tionStrip Foundation refers to a kind of buding foundation whose base length is much greater than the width of a base form,it is also the structure of the hybrid structures commonly used foundation form.Because of the hybrid structure with walls as vertical load-bearing building components,and its f11、orm the basis for determining the strip it is in the form of strips.Before laying the diamond strip foundation, soil compaction after the first general to do a plain concrete cushion.According to the form of the upper structure,strip foundation can be divided into strip foundation under the wall and12、 strip foundation under column,it is usually builded by brick,however,on the basis of the width is too wide, it is necessary to reduce the construction height, or in the wall needs to be strengthened to withstand the longitudinal tension caused by uneven settlement when, can also be constructed of r13、einforced concrete.2.1.1 Strip Foundation under the WallStrip foundation under the wall is divided into rigid and rigid concrete foundation strip foundation.And strip foundation masonry is used widely under the wall.When the upper wall of the load is large and when the soil is poor, consider the bro14、ad-based Shallow When reinforced concrete strip foundation under the wall.When the base wall extending direction when the load and soil when the compression uniform, in order to enhance the foundation of integrity and longitudinal bending ability, reduce the differential settlement, often with reinf15、orced concrete strip under ribbed girder wall foundation .This foundation is characterized by low cost, fast construction, through the strengthening of ground ring beam, and enhance the overall stiffness of the base, the upper structure can withstand greater load and adapt some deformation of founda16、tion.Conventional reinforced concrete wall is preferably in the form of a flexible foundation under strip footing.Larger load when the upper structure, foundation bearing capacity and low, and the foundation not very uniform, rigid base often make base section is too large, if designers want to keep17、 the shallow foundation, the foundation above the ground, but also increase if deepen the foundation earthworks the amount of the cost base.Even with rigid foundation, it is difficult to avoid a greater tensile basis, when the shear stress, foundation cracks appear uneven subsidence, cracks in the w18、all so as to cause the upper structure.Then the general use of reinforced concrete strip foundation, which can withstand greater bending moments and shear, with cross-sectional size and the amount of reinforcing steel base to meet the force requirements.If the ground is uneven, the beam can be stiff19、ened to enhance the bending ability, adjust differential settlement.2.1.2 Strip Foundation under ColumnLocal groups more weak, column loads or uneven ground compression that uses extended basis may have a greater uneven settlement, often in the same direction on the basis of a number of columns exce20、l integrally formed strip foundation under column.Strip foundation under column advantage is the basis of the bending stiffness, which has the ability to adjust uneven subsidence.2.2 Independent FoundationIndependent framework architecture is based on building common structural form.When using prefa21、bricated concrete pillars, often formed the basis of the shape of the cup, so that the post is inserted and secured in the cup mosaic.In order to avoid contact between independent foundation is weak and the situation is not good enough in the foundation or the superstructure load unevenness and sett22、lement, they tend to take the set foundation beams ways to strengthen the foundation of an independent building skeleton system integrity when unevenly distributed.Independent foundation independent foundation under the wall and collectively referred to as an independent foundation under column.Inde23、pendent foundation is a single base unreinforced or reinforcement of entire or partial structure under commonly used in the foundation plinth, chimneys, water towers, blast furnaces, machinery and equipment.Independent column is based on the most common and most basic form of economy. Scope independ24、ent basis: plinth, chimneys, water towers, blast furnaces, machinery and equipment, multi-storey residential, apartments, office buildings and so on.Independent foundation can be divided into two forms as follows:2.2.1 Independent Foundation under ColumnUnder the column independent foundation is the25、 basic form of the column base.,it can be divided into rigid base and flexible basis independence.Available rigid foundation bricks, rubble or plain concrete foundation stepped aspect ratio (rigid angle) to meet the specification.In general,reinforced concrete foundation of reinforced concrete colum26、n is appropriate to meet the rigid connection of columns and foundation assumed.Rigid or flexible basis independence and more generally the basis for the next column, the column load eccentricity according to the size of the foundation may be square or rectangular cross-section.When a large column s27、pacing, often as an independent foundation, this is more economical.To enhance the integrity of the foundation, also can pull beam Rachel appropriate, to enhance the ability to adapt to ground deformation and seismic.Multistoried buildings when the upper structure framework, such as high bearing cap28、acity of foundation, ground deformation is small, and column grid load more evenly distributed, should use independent foundation, but in both vertical and horizontal beams appropriate Fang Xiangyi pull then pull.Pull the beam cross-section to select appropriate, not too large, it can be determined 29、by calculation.In general,civil construction in the column, the majority can be considered independent foundation, rather than strip foundation, to meet the request of the bearing capacity and deformation, its economic effect is better.2.2.2 Independent Foundation under the WallWhen the building pas30、sed to the foundation of the load is not large, the lower bearing capacity is high, buried deep foundation needed, can be made into an independent foundation under the wall.2.3 Raft FoundationWhen the upper part of the building and the location of a large load carrying capacity surpasses weak founda31、tion and uneven foundation soil, reinforced concrete cross beams or strip foundation can not meet the requirements of the building, in order to carry in order to meet the needs or deformation of foundation needs, strip foundation or pillars under the following well format possible through expansion 32、of the wall together into one, so that the load of the building to withstand a whole plate, this foundation called raft foundation.This basis is usually used to be multilayer and high-rise buildings.For basement structure, which itself does not require water or moisture, raft foundation piece is jus33、t the basement floor structure.2.3.1 Classification of Raft FoundationAccording to constructed,raft foundation can be divided into flatbed raft foundation and beams raft foundation,according to structure type,it can be divided into under the column under the raft foundation and walls raft foundation34、.For high-rise buildings, the raft foundation framework called the next column under raft foundation, raft foundation under shear wall structure called raft foundation under the wall.For some uneven ground, and the soil and soft, it should be ground treatment.Improve the bearing capacity and reduce 35、the compressibility of the foundation, and then do the raft foundation on the treated piece of ground.This ground and foundation combined consideration, technical and economic results than those ideals.Comparision between flatbed raft foundation slab raft foundations and beams.Flatbed raft foundatio36、n:for basement space utilization, easy construction, but when a large column loads and uneven ground, a large raft thickness, compared with consuming material.Girder slab raft foundations:Stiffness, less consuming steel, more economical,but the construction is relatively cumbersome.Houston Commercia37、l Building, 305 meters high, is the tallest building in the world hosted by the raft foundation.All buildings are made of a whole raft foundation, the basis of the following in apartment buildings using plain concrete piles to reduce the differential settlement between buildings.2.3.2 Advantage of R38、aft FoundationSince the raft foundation itself greater rigidity, can effectively adjust the building when the differential settlement, especially in conjunction with the basement, the bearing capacity of the foundation is particularly advantageous.It also has a small cross shallow underground caves,39、 and enhance the overall seismic performance of buildings, as the basement, depot,pools and other impervious floor, etc. Functions.2.3.3 Scope of Raft FoundationIt is usually used into multi-storey buildings and high-rise building.High-rise buildings in the frame structure, wall structure, frame str40、ucture can be applied raft foundation, when the building of uneven settlement, may also raft foundation.3 The effect of ground on building foundationGround is not the part of building,and its impact on the building foundation depends on the location and condition of the force holding the soil layer 41、has sufficient strength, and soil distribution is uniform, whether there is likely to cause uneven subsidence of buildings and so on.Any natural soil itself has sufficient strength to withstand direct load building foundation is called the natural ground.If the natural carrying capacity of the soil 42、itself is weak, or the upper part of building a larger load shall advance artificial soil layer processing or treatment to make it reinforced to withstand the load of the building.This kind of ground is called artificial ground.These conditions can affect the building foundation embedment depth and 43、basic structure of the form.Designed from the ground to the embedment depth outside the vertical distance base called the base of the bottom surface, referred to as the basis of depth.In addition,ground water table situation on the basis of the building will have an impact.This effect mainly in term44、s of the depth of the building foundation and the basis of waterproof construction practices.We can get some materials about ground water table from ground area.And we should pay attention to whether it will freeze topsoil in winter.Which pay attention to whether the winter will freeze the soil surf45、ace. For the winter will freeze the surface area, the thickness of the ice is called frost line soil.For the winter will freeze the surface area, the thickness of the ice is called frost line soil.To prevent freezing melt by volume of water contained within the earth changes would adversely affect t46、he foundation, the foundation should be buried below the bottom surface 200 mm frost line.The above description is based on the importance of awareness.Through professional learning this semester,the author architectural engineering design has an intuitive understanding,and integrated use their acqu47、ired knowledge and expand reflected in the paper.During the study,the author the responsibilities and role of construction projects have more practical understanding, deeply understand the restrictions on the site of what is seen in engineering construction, also deeply realized to act on the construction industry must be more effort.From another point of view and way to sentiment building, not just in theory but also in practical applications.