Lesson Plan

• Review

• New Words and Phrases

• Reading and Translating—Unit Ten

• Classroom Exercises

Classroom Exercises An efficient analyst must thus be in command of the rig

orous methods of analysis, must be able to reduce these to shortcut methods by appropriate assumptions, and must be aware of available design and analysis aids, as well as simplifications permitted by applicable building codes. An up-to-date analyst must likewise be versed in the bases of matrix structural analysis and its use in digital computers as well as in the use of available analysis programs or software.

有能力的分析人员必须掌握严密的分析方法，必须能够通过适当的假设条件进行简化分析，必须了解可利用的标准设计和分析手段以及建筑规范中允许的简化方法。同时， 现代的分析人员必须精通结构矩阵分析的基本原理及其在数字计算机中的应用，会应用现有的分析程序及有关软件。

Unit Ten Types and Function of foundation

单 元 10基础的形式和功能

The purpose of a foundation is to carry the load of a structure and spread it over a greater area, evenly and without undue settlement, to the ground beneath.

The purpose of a foundation is to carry the load of a structure and spread it over a greater area, evenly and without undue settlement, to the ground beneath.

基础的作用是承受结构的荷载，并将其均匀地向更大更深的范围传递，避免过度的沉降。

The size and type of foundation depends on the nature of the ground and the load carried by it. The bearing capacity of a soil means the maximum load per unit area (usually in terms of KN/M2) which the ground will safely support.

The size and type of foundation depends on the nature of the ground and the load carried by it. The bearing capacity of a soil means the maximum load per unit area (usually in terms of KN/M2) which the ground will safely support.

基础的尺寸和类型取决于：地基的土质情况（地耐力），地基所承受的荷载（上部力）。土体的承载力（地耐力）即是单位面积上地基所能安全承受的最大荷载（通常表示为 KN/M2 ）。

All soils compress noticeably when loaded and cause the supported structure to settle. The two essential requirements in the design of foundations are that the total settlement of the structure shall be limited to a tolerably small amount and that differential settlement of the various parts of the structure shall be eliminated as nearly as possible.

All soils compress noticeably when loaded and cause the supported structure to settle. The two essential requirements in the design of foundations are that the total settlement of the structure shall be limited to a tolerably small amount and that differential settlement of the various parts of the structure shall be eliminated as nearly as possible.

所有土壤在受荷载作用时明显受到压缩，并引起所支承的建筑物沉降。在基础设计中有两个基本要求，一是结构物总的沉降要限制到尽量小的程度；二是要尽可能消除结构各部分的不均匀沉降。

With respect to possible structural damage, the elimination of differential settlement, i.e., different amounts of settlement within the same structure, is even more important than limitations on uniform overall settlement.

With respect to possible structural damage, the elimination of differential settlement, i.e., different amounts of settlement within the same structure, is even more important than limitations on uniform overall settlement.

就建筑物被破坏的可能性而言，避免不均匀沉降，即避免同一建筑物内的沉降差值，比限制均匀的总沉降更为重要。

To limit settlements as indicated, it is necessary (1) to transmit the load of the structure to a soil stratum of sufficient strength and (2) to spread the load over a sufficiently large area of that stratum to minimize bearing pressure.

To limit settlements as indicated, it is necessary (1) to transmit the load of the structure to a soil stratum of sufficient strength and (2) to spread the load over a sufficiently large area of that stratum to minimize bearing pressure.

为了限制上述沉降， (1) 必须把建筑物的荷载传递到有足够强度的土层； (2) 把荷载分布在该土层足够大的面积上，以减少支承压力。

If satisfactory soil directly underlies the structure, it is merely necessary to spread the load, by footings or other means. Such substructures are known as spread foundations, and it is mainly this type, which will be discussed.

If satisfactory soil directly underlies the structure, it is merely necessary to spread the load, by footings or other means. Such substructures are known as spread foundations, and it is mainly this type, which will be discussed.

如果正好在建筑物的下面就有良好的土层，仅需要用基础或其它手段来扩散荷载。这样的下部结构叫做扩展式基础，我们要讨论的正是这种基础。

Spread foundations generally can be classified as wall and column footings. A wall footing is simply a strip of reinforced concrete, wider than the wall, which distributes its pressure. Single-column footings are usually square, sometimes rectangular, and represent the simplest and most economical type.

Spread foundations generally can be classified as wall and column footings. A wall footing is simply a strip of reinforced concrete, wider than the wall, which distributes its pressure. Single-column footings are usually square, sometimes rectangular, and represent the simplest and most economical type.

扩展基础通常可分为墙基和柱基。墙基只不过是比墙稍宽的钢筋混凝土条带，它分散墙体的压力。单柱基础通常是正方形，有时是长方形，都是最简单最经济的型式。

Combined footings under two or more columns are also used under closely spaced, heavily loaded interior columns, if single footings were provided, would comp1etely or nearly merge.

Combined footings under two or more columns are also used under closely spaced, heavily loaded interior columns, if single footings were provided, would comp1etely or nearly merge.

在间距小、荷载大的柱下也可采用双柱或多柱的联合基础。如果在这种情况下采用独立基础，它们将完全或几乎完全连成一块。

Such individual or combined column footings are the most frequently used types of spread foundations on soils of reasonable bearing capacity. If the soils weak and column loads are great, the required footing areas become so large as to be uneconomical. In this case, unless a deep foundation is called for by soil conditions, a raft foundation is resorted to.

Such individual or combined column footings are the most frequently used types of spread foundations on soils of reasonable bearing capacity. If the soils weak and column loads are great, the required footing areas become so large as to be uneconomical. In this case, unless a deep foundation is called for by soil conditions, a raft foundation is resorted to.

在有较好承载能力的土层上，上述单个柱基或复式柱基是扩展式基础的最常用形式。如果土质软且柱荷载大，需要的基础面积将太大而不符合经济要求。在这种情况下，除非根据土质条件需要深基，否则就采用筏板基础。

On compressible soils footings should be loaded concentrically to avoid tilting, which will result if bearing pressures are significantly larger under one side of the footing than under the opposite side. This means that single footings should be placed concentrically under the columns and wall footings concentrically under the walls and that for combined footings the center of the footings area should coincide with the resultant of the column loads.

On compressible soils footings should be loaded concentrically to avoid tilting, which will result if bearing pressures are significantly larger under one side of the footing than under the opposite side. This means that single footings should be placed concentrically under the columns and wall footings concentrically under the walls and that for combined footings the center of the footings area should coincide with the resultant of the column loads.

在压缩性土上，基础应中心加载，以避免由于基础一边的支承压力比另一边大得多而产生倾斜。这意味着单独基础应与柱对中，墙基应与墙对中，而复式基础的基底形心应与柱荷载合力相重合。

When a foundation is laid in poor soil, it is necessary to excavate to a greater depth than normal to reach a solid base. If a adequate base cannot be found at a reasonable depth, then a so-called deep foundation must be provided. This usually comprises a series of driven or cast-in-situ reinforced concrete piles.

When a foundation is laid in poor soil, it is necessary to excavate to a greater depth than normal to reach a solid base. If a adequate base cannot be found at a reasonable depth, then a so-called deep foundation must be provided. This usually comprises a series of driven or cast-in-situ reinforced concrete piles.

若将基础建在地基土层较差的地方，其基坑的深度必须大于常规深度，以使基础落于较坚实的地基上。若在合理的深度内找不到坚实的地基层，那就要采用深基础，如通常采用的打入式或现场灌注的钢筋混凝土桩基础。

Type of Foundation

(plain) concrete strip foundation under walls ——墙下（素）混凝土条形基础 (linear load)reinforced concrete isolated foundation under a column ——柱下钢筋混凝土独立基础 (concentrated (point) loa

d)reinforced concrete strip foundation under columns ——柱下钢筋混凝土条形基础raft foundation under walls （ columns ） ——墙（柱）下筏板基础box foundation——箱形基础 (also forms the basement.)pile foundation——桩基础 (pile type: cast-in-situ pile, prec

ast pile)