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1、1、外文原文（复印件）Foundation And Foundation EngineeringStrucures or other constructed works are supported on the earth by foundation. The word “foundation” may mean the earth itself, something placed in or on the earth to provide support, or a combinnation of the earth and the elements placed on it. The fo
2、undation for a multistory office building could be a combination for an earth-fill dam would be the natural soil or rock on which the dam is placed. Concrete footings or which or in which they are placed. The installed elements and the natural soil or rock of the earth form a foundation system; the
3、soil and rock provide the ultimate support of the system. Foundation that are installed may be either soil-bearing or rock -bearing. The reactions of the soil or rock to the imposed loads generally determined how well the foundation system functions. In designing the installed portions, the designer
4、 must determine the safe pressue which can be used on the soil or rock and the amount of total settlement and differential settlement which the structure can withstand.The installed parts of the foundation system may be footings, mat foundations, slab foundations, and caissons or piles, all of which
5、 are used to transfer load from a supersteucture into the earth. These parts, which transmit load from the superstructure to the earth, are called the substructure.Footing Footing or spread foundations are used to spread the loads from columns or walls to the underlying soil or rock. Normally, footi
6、ngs are constructed of reinfored concrete. However, under some circumstances they may be constructed of plain concrete or masonary, when each footing supports only one column, it is square. Footings supporting two coumns are called combined footings and may be either rectangular or trapezoidal. Cant
7、ilever footings are used to building line or exterior wall. Footings supportsing walls are continuous footings.The sizes of footings are determined by dividing the loads to be imposed at the base of the footings by the allowable bearing pressure which can be imposed on the soil or rock of the earth.
8、 Most building codes and textbooks on foundations contain tables listing allowable bearing pressures for various types of soil and rock; however , these tables give only general classifications and descriptions of the soil or rock must be used with caution. More specific information about the soil o
9、r rock is normally obtained by drilling test borings, extracting soil or rock samples, performing laboratory tests on the samples, and making engineering must be given to the amount of settlement which may occur and the capability of the structure to withstand such settement. If settlement is proble
10、m it may be necessary to use an alternate foundation type rather than footings or to enlarge the footings and decrease the bearing pressure.Grade beams may be used between exterior column footings to support walls, with the beams transferring the weight of the walls to the column footings. Beams are
11、 also used between interior column footings to act as braces or to support interior walls. Retaining walls are those walls subject to horizontal earth pressures due to the retention of earth behind them. The foundation for these will not slide when subjected to the horizontal earth pressure. In addi
12、tion.retaining walls must be designed so they will not overturn. In frost-susceptible areas, footings must be placed below the frost line.Mat foundations Mat or raft foundations are large, thick, and usually heavily reinforced concrete mats which transfer loads from a number or colums and walls to t
13、he underlying soil or rock. Mats are also combined footings.,but are much larger than a footing uniform pressure to the underlying soil or rock. Mats are rigid and will act as a bridge over discontinuities in the soil or rock on which they are founded. Mats founded several meters below the ground su
14、rface, when combined with external walls, are termed floating foundations. The weight of the soil excavated from the ground surface to the bottom of the mat may be equal to approach the total weight of the structure. In this case, little or no new load is applied to the underlying supporting soil, a
15、nd settlements of a structure may be minimal after construction.Slab foundations Slab foundations are used for light structures wherein the columns and walls are supportes directly on the floor slab. The floor slab is thickened and more heavily reinforced at the places where the column and wall load
16、s are imposed.Special problems Groundwater is a major problem in connection with the design and installation of foundations where a substructure is to be placed below the groundwater level. Well points, pumping from deep wells, or pumping from sumps are methods used to dewater construction sites during foundation installation. Other methods which are less often used are freezing of the water in the soul, removal of water by electroosmosis, and the installation of cutoff walls m
