土木工程专业英语全部惠宽堂

Lesson 1

Compression Members

New Words

1. achieve achievement

2. eccentricity center, 中心; ec centric 偏心的；ec centricity 偏心，偏心距

3. inevitable evitable 可避免的avoidable; in evitable 不可避免的unavoidable

4. truss 桁架triangular truss, roof truss, truss bridge

5. bracing brace 支柱，支撑；bracing, 支撑，撑杆

6. slender 细长，苗条；stout; slenderness

7. buckle 压曲，屈曲；buckling load

8. stocky stout

9. convincingly convince, convincing, convincingly

10. stub 树桩，短而粗的东西；stub column 短柱

11. curvature 曲率；curve, curvature

12. detractor detract draw or take away; divert; belittle，贬低，诽谤；

13. convince

14. argument dispute, debate, quarrel, reason, 论据（理由）

15. crookedness crook 钩状物，v弯曲，crooked 弯曲的

16. provision 规定，条款

Phrases and Expressions

1. compression member

2. bending moment shear force, axial force

3. call upon (on) 要求，请求，需要

4. critical buckling load 临界屈曲荷载critical 关键的，临界的

5. cross-sectional area

6. radius of gyration 回转半径gyration

7. slenderness ratio 长细比

8. tangent modulus 切线模量

9. stub column 短柱

10. trial-and-error approach 试算法

11. empirical formula 经验公式empirical 经验的

12. residual stress 残余应力residual

13. hot-rolled shape 热轧型钢hot-rolled bar

14. lower bound 下限upper bound 上限

16. effective length 计算长度

Definition （定义）

Compression members are those structural elements that are subjected only to axial compressive forces: that is, the loads are applied along a longitudinal axis through the centroid of the member cross section, and the stress can be taken as f a=P/A, where f a is considered to be uniform over the entire cross section. 受压构件是仅受轴向压力作用的构件，即：荷载是沿纵轴加在其截面形心上的，其应力可表示为…，式中，假定f a在整个截面上均匀分布。This ideal state is never achieved in reality, however, and some eccentricity of the load is inevitable. 然而，现实中从来都不可能达到这种理想状态，因为荷载的一些偏心是不可避免的。This will result in bending, but it can usually be regarded as secondary and can be neglected if the theoretical loading condition is closely approximated. 这将导致弯曲，但通常认为它是次要的，如果理论工况是足够近似的，就可将其忽略。This cannot always be done if there is a computed bending moment, and situation of this type will be considered in Beam-Columns. 但这并非总是可行的，如有计算出的弯矩存在时，这种情形将在梁柱理论中加以考虑。

The most common type of compression member occurring in buildings and bridges is the column, a vertical member whose primary function is to support vertical loads. 在建筑物和桥梁中最常见的受压构件就是柱，其主要功能就是支承竖向荷载。In many instances these members are also called upon to resist bending, and in these cases the member is a beam-column. Compression members can also be found in trusses and as components of bracing systems. 在许多情况下，它们也需要抵抗弯曲，在此情况下，将它们称为梁柱。受压构件也存在于桁架和支撑系统中。

Column Theory （柱理论）

Consider the long, slender compression member shown in Fig.1.1a. 考虑如图1.1.a所示的长柱If the axial load P is slowly applied, it will ultimately reach a value large enough to cause the member to become unstable and assume the shape indicated by the dashed line. 如果慢慢增加轴向荷载P，它最终将达到一个足够大的值使该柱变得不稳定(失稳)，如图中虚线所示。The member is said to have buckled, and the corresponding load is called th e critical buckling load. 这时认为构件已经屈曲，相应的荷载称为临界屈曲荷载。If the member is more stocky, as the one in Fig.1.1b, a larger load will be required to bring the member to the point of instability. 如果该构件更粗短些，如图1.1b所示，则需要更大的荷载才能使其屈曲。For extremely stocky members, failure may be by compressive yielding rather than buckling. 对特别粗短的构件，破坏可能是由受压屈服引起而非由屈曲引起。For these stocky members and for more slender columns before they buckle, the compressive stress P/A is uniform over the cross section at any point along the length. 对这些短柱以及更细长的柱，在其屈曲前，在其长度方向上任意点处横截面上的压应力P/A都是均匀的。As we shall see, the load at which buckling occurs is a function of slenderness, and for very slender members this load could be quite small. 我们将会看到，屈曲发生时的荷载是长细程度的函数，非常细长的构件的屈曲荷载将会很低。

If the member is so slender (a precise definition of slenderness will be given shortly) that the stress just before buckling is below the proportional limit—that is, the member is still elastic—the critical buckling load is given by 如果构件如此细长（随后将会给出细长程度的精确定义）以致即将屈曲时的应力低于比例极限—即，构件仍是弹性的，临界屈曲荷载如下式给出：

22L EI

P cr π= (1.1)

where E is the modulus of elasticity of the material, I is the moment of inertia of the cross-sectional area with respect to the minor principal axis, and L is the length of the member between points of support. 式中E 为材料弹性模量，I 为关于截面副主轴的惯性矩，L 为支座间的距离。For Eq1.1 to be valid, the member must be elastic, and its ends must be free to rotate but not translate laterally. This end condition is satisfied by hinges or pins. 要使方程1.1成立，构件必须是弹性的，且其两端必须能自由转动，但不能侧向移动。

This remarkable relationship was first formulated by Swiss mathematician Leonhard Euler and published in 1975. 此著名公式是瑞士数学家欧拉于1975年提出的。The critical load is sometimes referred to as the Euler load or the Euler buckling load. The validity of Eq.1.1 has been demonstrated convincingly by numerous tests. 因此有时将临界荷载称为欧拉荷载或欧拉临界荷载。欧拉公式的有效性（正确性）已由许多试验充分证实。

It will be convenient to rewrite Eq.1.1 as follows: 方程1.1可方便地写为 2222222)/(r L EA L EAr L EI

P cr πππ=== (1.1a)

where A is the cross-sectional area and r is the radius of gyration with respect to the axis of buckling. The ratio L/r is the slenderness ratio and is the measure of a compression member ’s slenderness, with large values corresponding to slender members. 式中A 为截面面积，r 为关于屈曲轴的回转半径，L/r 为长细比，它是对受压构件细长程度的一种度量，该值越大，构件越细长。

If the critical load is divided by the cross-sectional area, the critical buckling stress is obtained: 如果将屈曲荷载除以截面面积，便可得到以下屈曲应力： 22)/(r L E A P F cr cr π== (1.2)

This is the compressive stress at which buckling occur about the axis corresponding to r. 这便是绕相应于r 的轴发生屈曲时的压应力。Since buckling will take place as soon as the load reaches the value by Eq.1.1, the column will become unstable about the principle axis corresponding to the largest slenderness ratio. This usually means the axis with the smaller moment of inertia. 由于一旦荷载达到式1.1之值，柱将在与最大长细比对应的主轴方向变得不稳定（失稳），通常该轴是惯性矩较小的轴。Thus, the minimum moment of inertia and radius of gyration of the cross section should be used in Eq.1.1 and 1.2. 因此，应在方程1.1和1.2中采用截面的最小惯性矩和最小回转半径。

Early researchers soon found that Euler ’s equation did not give reliable results for stocky, or less slender, compression members. 早期的研究者很快发现对短柱或不太细长的受压构件，欧拉公式并不能给出可靠的结果，This is because of the small slenderness ratio for members of this type, which results in a large buckling stress (from Eq.1.2). 这是因为这种构件的长细比较小，从而产生较高的屈曲应力。If the stress at which buckling occurs is greater than the proportional limit of the material, the relation between stress and strain is not linear, and the modulus of elasticity E can no longer be used. 如果屈曲发生时的应力大于材料的比例极限，应力应变关系就不再是线性的，也不能再用弹性模量E 。

This difficulty was initially resolved by Friedrich Engesser, who proposed in 1889 the use of a variable tangent modulus E t in Eq.1.1. 这一困难最初由Friedrich Engesser 所克服，他在1889年将可变的切线模量用于方程1.1. For a material with a stress-strain curve like the one in Fig.1.2, E is not a constant for stress greater than the proportional limit F pl . The tangent modulus E t is defined as the slope of the tangent to the stress-strain curve for values of f between F pl and F y . 对于如图1.2所示的应力应变曲线(的材料)，当应力超过比例极限时，E 并非常数，当应力处于F pl 和F y 之间时，将切线模量定义为应力应变曲线的切线的斜率，If the compressive stress at buckling, P cr /A, is in this region, it can be shown that 如果屈曲时的压应力在此范围时，可以证明

22L I

E P t cr π= (1.3)

This is identical to the Euler equation, except that E t is substituted for E. 除公式中将E 代之以E t 外，上式与欧拉公式完全相同。

Effective Length （计算长度）

Both the Euler and tangent modulus equations are based on the following assumptions: 欧拉和切线模量方程都是基于如下假定：

1. The column is perfectly straight, with no initial crooked ness. 柱完全竖直，无初始弯曲。

2. The load is axial, with no eccentricity. 荷载是轴向加载，无偏心。

3. The column is pinned at both ends. 柱在两端铰结。

The first two conditions mean that there is no bending moment in the member before buckling. 前两(假定)条件意味着在屈曲前无弯矩存在。As mentioned previously, some accidental moment will be present, but in most cases it can be neglected. 如前所述，可能偶然会存在一些弯矩，但在大多数情况下都可被忽略。The requirement for pinned ends, however, is a serious limitation, and provisions must be made for other support conditions. 然而，铰结要求是一个严重的局限，必须对其它支撑条件作出规定。The pinned-end condition is one that requires that the member be restrained from lateral translation, but not rotation, at the ends. 铰结条件要求约束构件两端不发生侧移，但并不约束转动。Since it is virtually impossible to construct a frictionless pin connection, even this support condition can only be closely approximated at best. 由于实际上不可能构造无摩擦铰连接，即使这种支撑条件最多也只能是非常近似。Obviously, all columns must be free to deform axially. 显然，所有柱必须在轴向自由变形。 In order to account for other end conditions, the equations for critical buckling load will be written as 为了考虑其它边界条件，将临界荷载写为如下形式

22)/(r KL EA

P cr π= or 22)/(r KL A

E P t cr π= (1.4)

where KL is the effective length, and K is called the effective length factor. Values of K for different cases can be determined with the aid of the Commentary to the AISC Specification. 式中KL 为计算长度，K 称为计算长度系数，各种情况下的K 值可借助于AISC （美国钢结构学会American Institute of Steel Construction ）规范的条文说明加以确定。

Lesson 2

Introduction to structural design

New words

1. framework frame+work=frame 构架，框架; frame structure, 框架结构

2. constraint vt. constrain 约束，强迫；n. constraint 约束

3. collaborate vt. 合作，通敌；collaboration, collaborative

4. evaluation vt. evaluate, value; assess, assessment

5. fixture vt. fix, fixture 固定设备，固定物，夹具

6. partition vt. n 分割，划分，make apart; partition wall

7. overlook

8. crane n. 超重机，鹤

9. fatigue vt.vi.n 疲劳fatigue strength, fatigue failure

10. drift v.n 漂流，漂移，雪堆

11. enumerate v. list 列举

12. plumbing n. (卫生，自来水)管道，plumber 管道工

13. ventilation n. 通风，ventilate, ventilate a room, a well-ventilated room, vent 通风口

14. accessibility n. 可达性，access, n. vt. 通道，接近；accessible 易接近的，可达到的

15. code n. vt 代码，编码，规范

16. administer v. 管理，执行；administrate, 管理

17. metropolitan a. 大城市，of metropolis

18. consolidate v. 巩固，strengthen，reinforce; consolidation

19. prescription n. 规定，命令，药方；prescribe

20. municipality n. 市政当局，直辖市，municipal government

21. specification n. 详述，规格, 规范；specify

22. mandate n. 书面命令，委托，

Phrases and expressions

1. functional design 功能设计

2. bending moment 弯矩

3. dead load

4. live load

5. nonstructural components 非结构构件

6. force due to gravity

7. gravity load

8. building code

9. design specifications 设计规程

10. nonprofit organization 非赢利组织，弄non-government organization

11. the National Building Code

12. the Uniform Building Code

13. the Standard Building Code

14. Building Officials and Code Administrators International (BOCA) 国际建筑公务员与法规管

理人员联合会

15. AISC 美国钢结构学会American Institute of Steel Construction

16. AASHTO 美国公路和运输工作者协会

American Association of State Highway and Transportation Officials

17. AREA 美国铁道工程协会the American Railway Engineering Association

18. AISI 美国钢铁学会American Iron and Steel Institute Introduction to Structural Design

Structural design

The structural design of building, whether of structural steel or reinforced concrete, requires the determination of the overall proportions and dimensions of the supporting framework and the selection of the cross sections of individual members. 建筑结构设计，不论是钢结构还是钢筋混凝土结构，都需要确定其支承结构的整体比例和尺寸以及各构件的截面尺寸。In most cases the functional design, including the establishment of the number of stories and the floor plan, will have been done by an architect, and the structural engineer must work within the constraints imposed by this design. 在大多数情况下，功能设计，包括楼层层数和楼层平面的确定，将要由建筑师来完成，因而结构工程师必须在此约束条件下工作。Ideally, the engineer and architect will collaborate throughout the design process so that the project is completed in an efficient manner. 在理想状态下，工程师和建筑师将在整个设计过程中协同工作从而高效地完成设计工作。In effect, however, the design can be summed up as follows: 然而，事实上，设计过程可概括如下：The architect decides how the building should look; the engineer must make sure that it doesn’t fall down. 建筑师确定建筑物的外观，工程师必须确保其不会倒塌。Although this is an oversimplification, it affirms the first priority of the structural engineer: safety. Other important considerations include serviceability (how well the structure performs in terms of appearance and deflection) and economy. 尽管这样说过分简单，但它明确了工程师的第一个主要任务，即，确保安全。其它要考虑的因素包括适用性（就外观和挠曲而言其工作性能如何）。An economical structure requires an efficient use of materials and construction labor. Although this can usually be accomplished by a design that requires a minimum amount of material, savings can often be realized by using slightly more material if it results in a simpler, more easily constructed projects. 经济的结构要求对材料和人工的有效使用，尽管这通常都能通过要求最少材料来取得，但通过采用稍多的材料，但能使建筑物更简单和更容易建造常常会实现节约的目的。

Loads

The forces the act on a structure are called loads. They belong to one of two broad categories, dead load and live load. 作用在结构物上的各种力称为荷载，它们属于一两种广义类型，恒载和活载。Dead loads are those that are permanent, including the weight of the structure itself, which is sometimes called the self-weight. 恒载是那些永久荷载，包括结构自身的重量，有时也称为自重。Other dead loads in a building include the weight of nonstructural components such as floor coverings, suspended ceilings with light fixtures, and partitions. 其它建筑物恒载包括非结构构件的重量，如楼面面层、带有灯具的吊顶以及隔墙。All of the loads mentioned thus far are forces due to gravity and are referred to as gravity loads. 至此所提的各种荷载都是由重力所引起，因而称为重力荷载。Live loads, which can also be gravity loads, are those that are not as permanent as dead loads. 活载也可以是重力荷载，它们是那些不如恒载那样永久的荷载。This type may or may not be acting on the structure as any given time, and the location may not be fixed. 这类荷载可能也可能不总是作用在结构物上，且作用位置也可能不是固定的。Examples of live load include furniture, equipment, and occupants of buildings. 活荷载包括家具、设置和建筑物的居住者。In general, the magnitude of a live load is not as well defined as that of a dead load, and it usually must be estimated. In many cases, a given structural member must be investigated for various positions of the live load so that a potential failure situation is not overlooked. 通常，活荷载的大小不如恒载那样确定，常常必须估计。在许多情况下，必须研究活荷载作用在一给定的结构构件的各个位置以便不会漏掉每个可能的破坏情形。

Building codes

Building must be designed and constructed according to the provisions of a building codes, which is a legal document containing requirements related to such things as structural safety, fire safety, plumbing, ventilation, and accessibility to the physically disabled. 建筑物必须根据各种建筑规范的条款设计和建造，规范是一种法律文件，包含各种要求，如建筑安全、防火安全、上下水、通风和体残人的可达性等。A building code has the force of law and is administered by a governmental entity such as a city, a county, or, for some large metropolitan areas, a consolidated government. 建筑规范具有法律效力，由政府部位发布，如城市、县、对于大的城区，如联合政府。Building codes do not give design provisions, but they do specify the design requirements and constraints that must be satisfied. 建筑规范并不给出设计规定，但却规定设计必须满足的各种要求和约束条款。Of particular importance to the structural engineer is the prescription of minimum live loads for buildings. 对结构工程师特别重要的是建筑物的最小活荷载规定。Although the engineer is encouraged to investigate the actual loading conditions and attempt to determine realistic values, the structure must be able to support these specified minimum loads. 尽管鼓励工程师研究实际荷载工况以确定真实的荷载值，结构必须能支承这些规定的最小荷载。

Design specifications

In contrast to building codes, design specifications give more specific guidance for the design of

structural members and their connections. 与建筑规范不同，设计规程给出结构构件及其连接的更具体的指南。They present the guidelines and criteria that enable a structural engineer to achieve the objectives mandated by a building code. 它们给出各种方针和标准，使结构工程师能建筑规范所规定的目标。Design specifications represent what is considered to be good engineering practice based on their latest research. 根据其最新研究，设计规程结出认为是好的工程作法。They are periodically revised and updated by supplements or by completely new editions. 它们通过补充或通过发布新版本得到定期修订和更新。As with model building codes, design specifications are written in a legal format by nonprofit organizations. 如同一般建筑规范，设计规程由非赢利组织编写。They have no legal standing on their own, but by presenting design criteria and limits in the form of legal mandates and prohibitions, they can easily be adopted, by reference, as part of a building code. 尽管它们本身并无法律地位，但却以法令和禁令的形式给出设计准则和限制，以参考文献的形式，它们可容易地被录入，并作为建筑规范的一部分。

Lesson 3

New words

1. col`loidal 胶状的，胶体的，`colloid 胶体

2. sieve n,v. 筛，过筛，过滤

3. sample n.vt. 样品，取样specimen

4. mesh n.v 网孔，网格，分网格

5. `cumulative a. 积累的；cumulate, cumulation

6. grading n. 级配，等级；grade

7. sedimentation n. 沉淀; sediment

8. suspension n. 悬浮；suspend ~bridge cable-stayed bridge

9. agitate v. 搅动，混合；disturb

10. hydro meter n. （液体）比重计

11. viscosity n. 黏性；viscoidal

12. flaky n. 薄片状的，of flake

13. pipette n. 吸液管

14. ir recoverable a.

不可恢复的ir retrievable

15. con cave a. 凹的；con vex凸的

16. permeability n. 渗透性; permeate, permeable seep seepage Phrases and expressions

1. frost susceptibility 霜冻敏感性

2. sieving method 筛分法

3. semi-logarithmic curve 半对数曲线

4. grading curve 级配曲线

5. wet sieving 湿法筛分

6. dispersing agent 分散剂

7. Stoke’s law 斯托克定律

8. unit weight 重度

9. coefficient of grading 级配系数

10. sedimentation method 沉降法

11. particle-size distribution 粒径分布

Text Particle Size Analysis 粒径分析

The range of particle sizes encountered in soils is very wide: from around 200mm down to the colloidal size of some clays of less than 0.001mm. 在各种土中所遇到的粒径范围很大，大到200mm小到小于0.001mm的一些粘土胶粒。Although natural soils are mixtures of various-sized particles, it is common to find a predominance occurring within a relatively narrow band of sizes. 尽管天然土都是由各种粒径的颗粒组成，但通常可发现其主要组成颗粒出现在一个比较小的粒径范围内。When the width of this size band is very narrow the soil will be termed poorly-graded, if it is wide the soil is said to be well-graded. 当这一粒径范围非常小时，称这种土级配较差，而当其较大时，称这种土级配良好。A number of engineering properties, e.g. permeability, frost susceptibility, compressibility, are related directly or indirectly to particle-size characteristics. 土的许多工程特性，如渗透性、霜冻敏感性、可压缩性等都直接或间接的与土的级配特性有关。

Fig.3.1 shows the British Standard range of percentage of particle sizes. 图3.1为粒径百分数的英国标准范围。The particle-size analysis of a soil is carried out by determining the weight percentage falling within bands of size represented by these divisions and sub-divisions. 通过确定落入由这些粒径分组和子组所代表的粒径范围的重量百分比，对土进行粒径分析。In the case of a coarse soil, from which fine-grained particles have been removed or were absent, the usual process is a sieve analysis. 对于粗粒土，它里面的细粒土被除去或本身就无细颗粒，常用的方法就是筛分法。A representative sample of the soil is split systematically down to a convenient sub-sample size and then oven-dried. 此法是将要分析土的一代表样本系统地分为方便的子样本，然后烘干。This sample is then passed through a nest of standard test sieves arranged in descending order of mesh size. 再使烘干的土样通过一组筛孔尺寸由大至小放置的标准试验筛。The weight of soil retained on each sieve is determined and the cumulative percentage of the sub-sample weight passing each sieve calculated. 称量每个筛中剩下的土样的重量，并计算出通过每个筛的累计百分数。From these figures the particle-size distribution for the soil is plotted as a semi-logarithmic curve (Fig.3.2) known as grading curve. 根据这些数据，

Where the soil sample contains fine-grained particles, a wet sieving procedure is first carried out to remove these and to determine the combined clay/silt fraction percentage. 在土样中含有细土粒的场合，首先用湿筛分法将其除去，并确定粘粒/粉粒总共所占的分数。A suitable-sized sub-sample is first oven-dried and then sieved to separate the coarsest particles (>20mm). 将一适量的分土样烘干，并过筛分开最粗的颗粒（>20mm的颗粒）The sub-sample is then immersed in water containing a dispersing agent and allowed to stand before being washed through a 63 m(micron) mesh sieve. 然后将土样浸入含有分散剂的水中，并在将其用63微米筛过筛前搁置起来（并将其搁置一会，再用63micron的筛子过筛）。The retained fraction is again oven-dried and passed through a nest of sieves. 将筛中保留的部分烘干，并用一组筛子过筛。After weighing the fractions retained on each sieve and calculating the cumulative percentage

passing each sieve, the grading curve is drawn. 称量落在每个筛中土重，并计算出通过每个的累计百分数后，就可描出级配曲线。The combined clay/silt fraction is determined from the weight difference and expressed as a percentage of the total sub-sample weight. The coarsest fraction (>20mm) can also be sieved and the results used to complete the grading curve. 由重量差确定粘粒/粉粒的总重，并将其表示为子土样总重的百分数。最粗的部分（即粒径>20mm 的部分）也可被过筛，并用其结果完成级配曲线的绘制。

A further sub-division of particle-size distribution in the fine-grained fraction is not possible by the sieving method. 不能用筛分法对细粒部分的粒径分布作进一步分组。A process of sedimentation is normally carried out for this purpose. 通常必须用沉降法实现此目的。 A small sub-sample of soil is first treated with a dispersing agent and then washed through a 63μm sieve. 首先将一小子土样用分散剂进行处理，然后洗过63的筛子。The soil/water suspension is then made up to 500 ml, agitated vigorously for a short while and then allowed to settle. 再从中取出500ml的土/水悬浮液，充分搅拌一会后让其沉降。The procedure is based on Stoke’s law, which states that the velocity at which a spherical particle will sink due to gravity in a suspension is given by: 此方法是基于斯托克思定律，即在重力作用下球形颗粒在某一悬浮液中下降的速度为

Where d=diameter of particle 颗粒直径

γs =unit weight of the grain of particle 颗粒重度

γw =unit weight of the suspension fluid (usually water) 悬浮液的重度（通过为水的重度）η=vescosity of the suspension fluid （悬浮液的黏度）

The diameter of those particles that will have settled a given distance in a given time (t) may be obtained by rearranging Eq.3.1: 将式3.1变形得在给定时间t内，沉降一给定距离的那些颗粒的直径为

Usually h=100mm, 通常h=100mm, giving 由此给出

Samples taken at a depth of 100mm, at an elapsed time of t, will not, therefore, include particles of greater size than the diameter d given by Eq.3.2; 因此在，在深度100mm处，t 时间后所取的悬浮液中将不会有粒径大于式 3.2所给出的土粒; but the proportions of particles smaller than d in the suspension will remain unchanged. 但悬浮液中小于d的颗粒所占的比例仍保持不变。The procedure using a hydrometer consists of measuring the suspension density at a depth of 100mm at a series of elapsed-time intervals. 用液体比重计的方法包括以一系列时间间隔在深度100mm处测定悬浮液的比重。The percentage-finer values corresponding to particular diameter (i.e. particle sizes) are obtained from the density readings, and thus a grading curve for the fine-grained fraction may be drawn. 通过比重读数得到小于某一特定粒径的颗粒的百分数，从而可画出细粒部分的级配曲线。

Grading Characteristics

The grading curve is a graphical representation of the particle-size distribution and is therefore useful in itself as a means of describing the soil. 级配曲线是粒径分布的一种图形表达，因而可用来作为描述土的手段。For this reason it is always a good idea to include copies of grading

curves in laboratory and other similar reports. 因此，人们总是认为在实验室报告或其它报告里附上几份级配曲线是一种好做法。It should also be remembered that the primary object is to provide a descriptive term for the type of soil. 还应牢记的是我们的主要目的是提供对土的类型的描述性术语。This is easily done using the type of chart by estimating the range of sizes included in the most representative fraction of the soil. 这可容易地通过采用这种级配曲线做到，因为用它能估计出土中最有代表性的成分的粒径范围。For example, the steep curve may be taken to represent a poorly-graded medium sand, indicating a narrow range of sizes. 例如，陡峭的曲线可用来表示级配差的中砂，并表示其粒径范围比较小。

A further quantitative analysis of grading curves may be carried out using certain geometric values known as grading characteristics. 通过采用某些称为级配特征的几何值，可进一步对级配曲线进行定量的分析。First of all, three points are located on the grading curve to give the following characteristic sizes: 首先，定出级配曲线上的三个点以给出以下特征粒径：

D10=maximum size of the smallest 10 percent of the sample; 只有10%土样通过的最大粒径；D30= maximum size of the smallest 30 percent of the sample; 只有30%土样通过的最大粒径；D60= maximum size of the smallest 60 percent of the sample；只有60%土样通过的最大粒径；From these characteristic sizes, the following grading characteristics are defined: 根据这些特征粒径，定义出如下级配特征：

Effective size 有效粒径

Uniformity coefficient 均匀系数

Coefficient of gradation 级配系数

Lesson 4

New Words

1.undergo[ ?nd????u] vt. 经历, 遭

受, 忍受; experience

2.evaporation [i v?p??rei??n] n.蒸发

(作用)

evaporate vapor

3.attribute [??tribju(:)t] vt.把…归因于,

把…归咎于，加于, 归结于;

ascribe，impute，credit，assign，refer 4.shrinkage shrink [ ?rinkid ] n.收缩shrink

5.capillary[k??pil?ri] adj. 毛细作用的

tension

capillarity

6.evaporate [i v?p?reit]v.(使)蒸发, 消失

7.paste [peist] n.糊, 粘土团cement paste

8.ambient[ ?mbi?nt] adj. 周围的,包围着10.distribution[ distri bju:??n]n.分配,

分发distribute

distributor

11. upwind[ ?p wind]adj.逆风的adv.逆风地windward; leeward

12.diminish[di mini?]v.(使)减少, (使)变小

diminishment; decrease

13.creep [kri:p] n. 徐变;

14.slippage slip [ slipid ] n.滑动, 滑移, 滑

程slip

15.humidity [hju: miditi]n.湿气, 潮湿, 湿

度;

humid

relative humidity

16.aug`ment[ : ??ment] v.增加, 增大n.

增加; increase, enlarge

的surrounding ambient air

9.specimen[ spesimin] n. 标本, 样品, 样

本, 待试验物; sample augmentation

17.sustained[s?s teind]adj.持续不变的, 相

同的; sustainable development

18.fatigue[f??ti:?]n.疲乏, 疲劳, vt.使疲

劳, vi.疲劳strength

Phrases and Expressions

1.moisture content 含水量，含湿度; water

content

2.cement paste 水泥浆mortar

3.capillary tension 毛细管张力，微张力

4.gradation of aggregate 骨料级配coarse

fine (crushed stone, gravel)

5.The British Code PC100英国混凝土规范

PC100; nowaday BS8110

6.coefficient of thermal expansion of

concrete 混凝土热膨胀系数

7. The B.S Code 英国标准规范8.sustained load 永久荷载，长期荷载

9.permanent plastic strain 永久的塑性应变

stress

10.crystal lattice晶格, 晶格

11.cement gel 水泥凝胶体

12.water-cement ratio 水灰比

13.expansion joint 伸缩缝

14.stability of the structure 结构的稳定性

structural stability

15. fatigue strength of concrete 混凝土的疲劳

强度

Text Volume Changes of Concrete

Concrete undergoes volume changes during hardening. 混凝土在硬结过程中会经历体积变化。If it loses moisture by evaporation, it shrinks, but if the concrete hardens in water, it expands. 如果蒸发失去水分，混凝土会收缩；但如果在水中硬结，它便膨胀。The causes of the volume changes in concrete can be attributed to changes in moisture content, chemical reaction of the cement with water, variation in temperature, and applied loads. 混凝土体积变化的原因可归结为含水量的变化、水泥与水的水化反应、温度变化和所施加的荷载。

Shrinkage

The change in the volume of drying concrete is not equal to the volume of water removed. The evaporation of free water causes little or no shrinkage. 混凝土干燥时的体积变化量不等于它所失去的水的体积。自由水的蒸发基本不产生收缩。As concrete continues to dry, water evaporates and the volume of the restrained cement paste changes, causing concrete to shrink, probably due to the capillary tension that develops in the water remaining in concrete. 随着混凝土的不断变干，水分蒸发，受约束水泥浆的体积也变化，导致了混凝土的收缩，这多半是由于残留在混凝土中的水的毛细张力所致。Emptying of the capillaries causes a loss of water without shrinkage. But once the absorbed water is removed, shrinkage occurs. 毛细管变空导致无收缩的水分丢失，但一旦失去吸收的水分，收缩便发生。

Many factors influence the shrinkage of concrete caused by the variations in moisture

conditions. 许多因素都会影响因水分环境发生变化而产生的混凝土收缩。

1.Cement and water content. The more cement or water content in the concrete mix, the greater the shrinkage. 水灰比：水灰比越大，收缩越大；

https://www.360docs.net/doc/1211857321.html,position and fineness of cement. High-early-strength and low-heat cements show more shrinkage than normal portland cement. The finer the cement, the greater is the expansion under moist conditions. 水泥的成分和细度：早强和低热水泥的收缩大于普通水泥，水泥越细，其在潮湿环境中的膨胀越大。

3.Type, amount, and gradation of aggregate. The smaller the size of aggregate particles, the greater is the shrinkage. The greater the aggregate content, the smaller is the shrinkage. 骨料的类型、含量及其级配：骨料的粒径越小，收缩越大；骨料含量越大，收缩则越小。

4.Ambient conditions, moisture, and temperature. Concrete specimens subjected to moist conditions undergo an expansion of 200 to 300×10-6, but if they are left to dry in air, they shrink. High temperature speeds the evaporation of water and, consequently, increases shrinkage. 外部条件，水分与温度：潮湿环境下的混凝土试件的膨胀量为200 to 300×10-6，但如果让其在空气中干燥，它们将收缩。高温加速了水分的蒸发，因此也加快了收缩。

5.Admixtures. Admixtures that increase the water requirement of concrete increase the shrinkage value. 添加剂：使用水量增加的外加剂也增加了收缩值。

6.Size and shape of specimen. As shrinkage takes place in a reinforced concrete member, tension stresses develop in the concrete, and equal compressive develop in the steel. These stresses are added to those developed by the loading action. Therefore, cracks may develop in concrete when a high percentage of steel is used. Proper distribution of reinforcement, by producing better distribution of tensile stresses in concrete, can reduce differential internal stresses. 试件的尺寸和形状：当收缩在钢筋混凝土构件中发生时，混凝土中产生拉应力，同样大小的压力产生于钢筋中，这些力与荷载引起的力相迭加。因此，当钢筋的配筋率高时，可能会使混凝土开裂。钢筋的合理分布、会使混凝土中的拉应力分布更有利，可减小内部应力差。

The values of final shrinkage for ordinary concrete vary between 200 and 700×10-6. 普通混凝土的收缩应变终值在200and 700×10-6之间。For normal-weight concrete, a value of 300×10-6 may be used. 对常重混凝土，收缩应变终值可取为300×10-6The British Code CP100 gives a value of 500×10-6, which represents an unrestrained shrinkage of 1.5 mm in 3 m length in thin, plain concrete sections. 英国CP100规范不出的收缩应变终值为500×10-6，这表示3m 长素混凝土薄截面构件的非约束收缩为1.5mm. If the member is restrained, a tensile stress of about 10N/mm2 (1400 psi) arises. 如果此构件受到约束，便产生了大约10N/mm2 (1400 psi) 的拉应力。If concrete is kept moist for a certain period after setting, shrinkage is reduced; 如果凝结后将混凝土保持在潮湿环境中，可减小其收缩。therefore, it is important to cure the concrete for a period of no fewer than 7days. 因此，将混凝土至少在潮湿环境中养护7天非常重要。

Exposure of concrete to wind increases the shrinkage rate on the upwind side. 将混凝土置于风中将增加其在迎风一侧的收缩速率。Shrinkage causes an increase in the deflection of structural members, which in turn increases with time. 收缩引起结构构件的挠度增大，而挠度也随时间而增长。Symmetrical reinforcement in the concrete section may prevent curvature and deflection due to shrinkage. 混凝土截面的对称配筋可防止因收缩而产生的曲率和挠度。

Generally, concrete shrinks at a high rate during the initial period of hardening, but at later stages the rate diminishes gradually. 通常，在硬结初期，混凝土收缩较快，但在后期，收缩速度会慢慢变小。It can be said that 15% to 30% of the shrinkage value occurs in 2 weeks, 40% to 80% occurs in 1 month, and 70% to 85% occurs in 1 year. 可以说15% to 30%收缩量的发生在

前两周，40% to 80%发生在前一个月，70% to 85%发生在第一年。

Expansion Due to Rise in Temperature 升温膨胀

Concrete expands with increasing temperature and contracts with decreasing temperature. The coefficient of thermal expansion of concrete varies between 4and7×10-6 per degree Fahrenheit. 混凝土受温膨胀，变冷时收缩。An average value of 5.5×10-6 per degree Fahrenheit (12×10-6 per degree Celsius) can be used for ordinary concrete. 一般混凝土的平均收缩值为每华氏度5.5×10-6（或每摄氏度12×10-6）。The B.S.Code suggests a value of 10-5 per degree Celsius. 英国标准规范的建议值为每摄氏10-5 This value represents a change of length of 10 mm in a 30-m member subjected to a change in temperature of 33℃. If the member is restrained and unreinforced, a stress of about 7N/mm2 (1000 psi) may develop. 这一值表示如果30m长的构件温度变化33度，其长度变化为10mm. 如果该构件受到约束但并未配筋，由此产生的应力可能约为7N/mm2 (1000 psi)。

In long reinforced concrete structures, expansion joints must be provided at lengths of 100 to 200 ft (30 to 60m). 在较长的钢筋混凝土结构中，每隔100英尺到200英尺（30m至30m）必须留伸缩缝。The width of the expansion joint is about 1 in. (25 mm). 伸缩缝宽度约为1英寸（25mm）Concrete is not a good conductor of heat, whereas steel is a good one. The ability of concrete to carry load is not much affected by temperature. 混凝土并非好的热导体，但钢材却是。因此混凝土的承载能力并不太受温度的影响。

Greep 徐变

Concrete is an elastoplastic material, and beginning with small stresses, plastic strains develop in addition to elastic ones. 混凝土是一种弹塑性材料，即使受低应力作用，它就产生伴有弹性应变的塑性应变。Under sustained load, plastic deformation continues to develop over a period that may last for years. 在持续荷载作用下，在很长时间内其塑性变形连续增长，甚至可达数年。Such deformation increases at a high rate during the first 4months after application of the load. This slow plastic deformation under constant stress is called creep. 此变形在加载后的前4个月最快。这种在持续应力作用下的缓慢变形称为徐变。

Figure 2.5 shows a concrete cylinder that is loaded. 图2.5表示受荷载作用的一混凝土圆柱体。The instantaneous deformation isε1, which is equal to the stress divided by the modulus of elasticity. 其瞬时变形为ε1，它等于应力除以弹性模量。If the same stress is kept for a period of time, an additional strainε2, due to creep effect, can be recorded. 如果将此应力保持一段时间，便可测出另一由徐变所产生的应变增量ε2，If load is then released, the elastic strain,ε1, will be recovered, in addition to some creep strain. 如果卸去荷载，弹性应变便得到恢复，同时还产生一些徐变应变。The final permanent plastic strain,ε3, will be left, as shown in Figure 2.5. 最终会剩下永久塑性应变ε3，如图2.5所示。In this caseε3=(1－α)ε2, whereαis the ratio of the recovered creep strain to the total creep strain. 在此情况下，ε3=(1－α)ε2, α是恢复徐变应变与总徐变的比值。The ratioαranges between 0.1and 0.2. 其值在0.1至0.2之间。The magnitude of creep recovery varies with the previous creep and depends appreciably upon the period of the sustained load. 徐变后效的大小随先前徐变的大小而变化，且在很大程度上取决于荷载的持续时间。Creep recovery rate will be less if the loading period is increased, probably due to the hardening of concrete while in a deformed condition. 如果持荷时间增加，徐变恢复率

将变小，这大概是由于混凝土在变形硬化所致。

Figure 2.5 Deformation in a loaded concrete cylinder: (a) specimen unloaded, (b) elastic

deformation,

(c) elastic plus creep deformation, (d) permanent deformation after release of load.

The ultimate magnitude of creep varies between 0.2×10-6 and 2×10-6 per unit stress (1b/in.2) per unit length. A value of 1×10-6can be used in practice. The ratio of creep strain to elastic strain may be as high as 4.

Creep takes place in the hardened cement matrix around the strong aggregate. It may be attributed to slippage along planes within the crystal lattice, internal stresses caused by changes in the crystal lattice, and gradual loss of water from the cement gel in the concrete. 徐变在强度更高的骨料周围的硬结的水泥基中产生，这可能是由于沿晶格中一些平面发生滑移、晶格变化所产生的内部应力、及混凝土凝胶体中水分不断丢失的结果。

The different factors that affect the creep of concrete can be summarized as follows. 影响徐变的各种不同因素可概括如下：

1. The level of stress. Creep increases with an increase of stress in specimens made from concrete of the same strength and with the same duration of load. 应力大小：

2. Duration of loading. Creep increases with the loading period. About 80% of the creep occurs within the first 4 months; 90% occurs after about 2 years. 持荷时间：

3. Strength and age of concrete. Creep tends to be smaller if concrete is loaded at a late age. Also, creep of 2000 psi-(14N/mm2-) strength concrete is about 1.41×10-6whereas that of 4000 psi- (28N/ mm2-) strength concrete is about 0.8×10-6 per unit stress and length of time. 混凝土强度和龄期：

4.Ambient conditions. Creep is reduced with an increase in the humidity of the ambient air. 周围环境条件：

5.Rate of loading. Creep increases with an increase in the rate of loading when followed by prolonged loading. 加载速率：

6.Percentage and distribution of steel reinforcement in a reinforced concrete member. Creep tends to be smaller for higher proportion or better distribution of steel. 钢筋混凝土结构中钢筋的配筋率及其分布：

7.Size of the concrete mass. Creep decreases with an increase in the size of the tested specimen. 混凝土尺寸：

8.Type, fineness, and content of cement. The amount of cement greatly affects the final creep of concrete, as cement creeps about 15 times as much as concrete. 水泥的类型、细度和含量：

9.Water-cement ratio. Creep increases with an increase in the water-cement ratio. 水灰比：

10.Type and grading of aggregate. Well-graded aggregate will produce dense concrete and consequently a reduction in creep. 骨料的类型和级配：

11.Type of curing. High-temperature steam curing of concrete as well as the proper use of a plasticizer will reduce the amount of creep. 养护方式：

Creep develops not only in compression, but also in tension, bending, and torsion. 徐变不仅产生于受压，它也产生于受拉，受弯和受扭。

The ratio of the rate of creep in tension to that in compression will be greater than 1 in the first 2 weeks, but this ratio decreases over longer periods. 受拉徐变的速率与受压徐变的速率之比在前两周将大于1，但会在长时间内减小。

Creep in concrete under compression has been tested by many investigators. Troxell, Davis, and Raphael measured creep strains periodically for up to 20 years and estimated that of the total creep after 20 years , 18% to 35% occurred in 2 weeks , 30% to 70% occurred in 3 months , and 64% to 83% occurred in 1 year . 许多研究者都对混凝土的受压徐变进行了试验研究。

For normal concrete loaded after 28 days , 313.0t C r =, where r C = creep strain per unit stress per unit length. 对28天龄期加载的普通混凝土，313.0t C r =，r C =单位应力下单位时间内的徐变。Creep augments the deflection of reinforced concrete beams appreciably with time. In the design of reinforced concrete members, long-term deflection may be critical and has to be considered in proper design. 随时间的增加，徐变会大大增加钢筋混凝土梁的挠度。Extensive deformation may influence the stability of the structure. 过大的变形会影响结构的稳定性。

Sustained loads affect the strength as well as the deformation of concrete. 持续加载会影响混凝土的强度和变形。A reduction of up to 30% of the strength of unreinforced concrete may be expected when concrete is subjected to a concentric sustained load for 1 year . 当混凝土在持续集中荷载作用下长达一年时，其钢筋混凝土的强度可能要降低30%.

The fatigue strength of concrete is much smaller than its static strength. 混凝土的疲劳强度大大低于其静力强度。Repeated loading and unloading cycles in compression lead to a gradual accumulation of plastic deformations. 受压的重复加载和卸载会导致混凝土塑性变形的逐渐积累。If concrete in compression is subjected to about 2 million cycles, its fatigue limit is about 50% to 60% of the static compression strength. In beams, the fatigue limit of concrete is about 55% of its static strength. 如果混凝土不断受压加载2百万次，其疲劳强度容许值会降为其静态抗压强度的50%至60%. 在梁中，混凝土的疲劳强度约为其静态强度的55%.

Lesson 7

New words

1. tamping

n. 夯实，捣紧；tamp, compact 2. fill

n, vt. 填方；填土 3. peat

n. 泥煤，泥炭块；Partially carbonized vegetable matter 4. flexing

n. 挠曲；flex, deflect, flexure, flexural

5. vegetation n. 植被

6. poplar n. 白杨

7. shrub n. 灌木，arbor乔木

8. seeding n. 树苗，秧苗

9. pruning n. prune，修剪

10. pollard vt. 修剪树枝

11. desiccation n. 干燥；desiccate, dry

12. loess n. 黄土；loess plateau

13. sewer n. 下水道，污水管；sewage; drainage

14. coffer n. 围堰；coffer dam

15. piping n. 管涌

16. matrix n. 胶结材料，矩阵

17. swallet n. 地下川；溪流入地下的进口

18. `subsidence n. settlement; subside, settle

19. excavation n. 开挖，excavate, cut

20. seepage n. 渗流，渗透；seep, permeate

21. rolling n. 碾压，轧制

22. untimbered n. 无支撑的；timbering

Phrases and Expressions

1. brick and masonry construction

2. site investigation 场地勘察

3. self-weight loading

4. surface surcharge 表面超载

5. immediate or undrained settlement 瞬时沉降或不排水迫降

6. water content

7. liquid limit

8. plasticity index

9. water table

10. hydrostatic pore pressure

Text Soil Compressibility and Settlement

Types of Ground Movement and Causes of Settlement

The relationship between ground movement and the stability of related structures is a complex one. 地面运动和相关结构稳定性之间的关系比较复杂。First of all, there are several mechanisms which may produce ground movement, and furthermore there are many types of structure, each with a varying potential to withstand or to be distressed by movement. 首先，导致地面运动的机理有多种，而且，结构形式也多种多样，每一种抵抗地面运动的能力也不同。Some buildings,

such as those of brick and masonry construction, are exceedingly brittle and may sustain cracks and even structural damage following very small foundation displacements. 一些建筑物，如砖石结构，脆性很大，即使在很小的基础位移发生时就可能导致其开裂，甚至结构破坏。Others may be constructed to sustain movements of considerable magnitude without suffering real damage.其它结构形式可经受很大的地面运动而不发生真正破坏。

Compaction

Compaction is a process whereby the soil particles are forced into a closer state of packing with a corresponding reduction in volume and the expulsion of air. 夯实是强迫土粒以更密集的形式堆积，从而导致其体积减小和空气被排出的过程，An input of mechanical energy is required and this is usually the result of self-weight loading or a surface surcharge. 夯实需要输入机械能，这通常是自重加载或地面附加荷载的结果。Vibrations due to traffic movement, heavy machinery and certain construction operations, such as pile-driving, have also been known to cause compaction settlement. 而且我们知道，由交通车辆引、重型机械和某些施工工作，如打桩等产生的振动也是夯实沉降的原因。In earthquake zones, seismic shock waves may have a similar effect. 在地震区，地震波也可能具有类似的功效。The most susceptible soils are loosely-packed sands or gravel-sands and fill material, particularly that which has been placed without adequate rolling or tamping. 最易受振动作用的土包括松砂土、松砾砂土和填土，特别是未经充分碾实和夯实时。

Consolidation

In saturated cohesive soils the effect of increasing the load is to squeeze out some of the porewater, this process is called consolidation. 在饱和粘性土中，增加荷载的效果就是将一些空隙水从土中挤出去，这一过程称为固结。A gradual reduction in volume takes place until internal pore pressure equilibrium is reached; a reduction in loading may cause swelling providing that the soil can remain saturated. 其体积逐渐减小直到空隙水压力达到平衡为止；如果土仍能处于饱和状态，减载可引起土的膨胀。A large part of the remainder of this chapter is devoted to detailed study of the consolidation process and to methods of assessing resulting settlements. 本章剩余的大量篇幅将详细研究土的固结过程及其由此引的起沉降的计算方法。It is essential to understand that a change in loading is required to start the process and that it may take several years for the final settlement to be achieved. 极为重要的就是要明白必须有荷载的变化来产生此过程，且最终沉降可能需要数年才能完成。

Elastic Volumetric Settlement弹性体积沉降

In overconsolidated clays increases in effective stress which do not exceed the yield point cause elastic (approximately) compression. 在超固结土中，有效土压力的增加将导致土的弹性（大约为弹性）的压缩，如果土压力未超过其屈服点。As the stress increases beyond the yield point, non-linear (consolidation) settlement occurs. 而当其压力增至超过其屈服点后，非线性（即固结）沉降便发生。In heavily overconsolidated clays, therefore, since the yield point will be very

high, settlement calculations can be based on elastic theory, using parameters referred to effective stresses. 因此，对严重超固结粘土，由于其屈服点很高，其沉降计算可根据弹性理论进行，并用其有效应力所对应的诸参数。Alternatively, estimates may be based on the slope of the swelling-recompression curve. 也可根据其膨胀—再压缩曲线的斜率估计其沉降。The elastic behavior of clays is probably attributable to the flexing of thin and flaky clay particles. 粘土的弹性可能是来自其薄的片状颗粒的弯曲。

Immediate or Undrained Settlement瞬时（或不排水）沉降

Immediate or undrained settlement is that amount that takes place during the application of loading, but before any significant volume change has occurred. 瞬时（或不排水）沉降是加载过程中的沉降，此时土还未发生大的体积变化。Although it theoretically occurs in all loading situations, with slowly applied loading, it is masked by consolidation settlement as volume changes occur. 尽管理论上讲，在各种加载过程中都发生此类沉降，但它被伴有体积变化的固结沉降所掩盖。The calculation of amounts of immediate settlement are therefore normally related to quickly applied loading e.g., beneath building structure. 因此，瞬时沉降量的计算通常与快速加载有关，例如，建筑物下面的沉降。The undrained stiffness (E u) can be assumed as an elastic constant for a given depth and so estimates can be obtained using elastic theory. 可将某一给定深度处土的不排水刚度假定为弹性常数，从而用弹性理论估计其沉降量。

Moisture Movement水分移动

Some types of clay show a marked increase or decrease in volume as the water content is respectively increased or decreased. 当一些粘土的含水量增加或减小时，会伴随着明显的体积增大或减小。Clays exhibiting these characteristics are alternatively called shrinkable clays or expansive clays and are found in certain areas of the southern and eastern countries. 具有此特性的粘土也称之为可收缩土或膨胀土，它们常出现在南部和东部的一些地区。

Effects of Vegetation植被的影响

Another factor associated with highly plastic clays that may bring about settlement is the effect of the roots of trees. 使高塑性土沉降的另一因素就是树木根的作用。The radial extent of some tree root systems is greater than the height of the tree; they may also reach depths of several meters. 一些树根系的径向沿伸要大于其高度，它们也可能有几米深。A movement of 100mm was recorded in house foundations 25m away from a row of poplars. 在相距一排白杨树25m的房屋的基础上曾观测到100mm的位移。The removal of such trees means that more moisture is held in the soil and so swelling occurs. 将这些树移走意味着土中的含水量将增加，从而土将发生膨胀。Where well-established trees and shrubs have to be removed from a site, a period of one or two winters should be allowed so that equilibrium may be achieved. 在要移走大量树木的场地上建造房屋时，要等一两个冬季过后，土中水分达到平衡后再动工。