土木工程专业英语全部惠宽堂

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2024年5月16日发(作者：)

Lesson 1

Compression Members

New Words

1. achieve achievement

2. eccentricity center, 中心; eccentric 偏心的；eccentricity 偏心，偏心距

3. inevitable evitable 可避免的 avoidable; inevitable 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 the 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：

2

P

cr





2

EI

L

2

(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

P

cr





2

EI

L

2





2

EAr

2

L

2





2

EA

(L/r)

2

(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：

P

cr



2

E

F

cr



A(L/r)

2

(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。

3

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

P

cr





2

E

t

I

L

2

(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 crookedness. 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

P

cr





2

EA

(KL/r)

2

or

P

cr





2

E

t

A

(KL/r)

2

(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。

4

Lesson 2

Introduction to structural design

New words

1. framework

2. constraint

3. collaborate

4. evaluation

5. fixture

6. partition

7. overlook

8. crane

9. fatigue

10. drift

11. enumerate

12. plumbing

13. ventilation

14. accessibility

15. code

16. administer

17. metropolitan

18. consolidate

19. prescription

20. municipality

21. specification

22. mandate

frame+work=frame 构架，框架; frame structure, 框架结构

vt. constrain 约束，强迫；n. constraint 约束

vt. 合作，通敌；collaboration, collaborative

vt. evaluate, value; assess, assessment

vt. fix, fixture 固定设备，固定物，夹具

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

n. 超重机，鹤

.n 疲劳 fatigue strength, fatigue failure

v.n 漂流，漂移，雪堆

v. list 列举

n. (卫生，自来水)管道，plumber 管道工

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

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

n. vt 代码，编码，规范

v. 管理，执行；administrate, 管理

a. 大城市，of metropolis

v. 巩固，strengthen，reinforce; consolidation

n. 规定，命令，药方；prescribe

n. 市政当局，直辖市， municipal government

n. 详述，规格, 规范；specify

n. 书面命令，委托，

Phrases and expressions

1. functional design

2. bending moment

3. dead load

4. live load

5. nonstructural components

6. force due to gravity

7. gravity load

8. building code

功能设计

弯矩

非结构构件

5

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

18. AISI

美国铁道工程协会

美国钢铁学会

the American Railway Engineering Association

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。

6

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

7

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。

8

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 . 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. hydrometer 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. irrecoverable a.

不可恢复的 irretrievable

15. concave a. 凹的；convex 凸的

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

Phrases and expressions

1. frost susceptibility

2. sieving method

3. semi-logarithmic curve

4. grading curve

5. wet sieving

6. dispersing agent

7. Stoke’s law

8. unit weight

9. coefficient of grading

10. sedimentation method

11. particle-size distribution

霜冻敏感性

筛分法

半对数曲线

级配曲线

湿法筛分

分散剂

斯托克定律

重度

级配系数

沉降法

粒径分布

9

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，

以半对数曲线的形式描出该土的粒径分布图，即所谓的级配曲线。

细粒

粘土

胶粒

粉土

细

中

粗

粗粒

砂

细

中

粗

砾石

细

中

粗

非常粗大颗粒

石块

卵石

块石

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

10

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 63m

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



s

=unit weight of the grain of particle 颗粒重度



w

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

=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

11

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

12

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

13

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。

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；

ition 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。

, 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。

t 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。

ures. 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。

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200 and 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

-6

The 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/mm

2

(1400 psi) arises. 如果此构件受到约束，便产生了大约10N/mm

2

(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 7 days. 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

14

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 4 and 7×10

-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 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/mm

2

(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/mm

2

(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 4 months 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 is

ε

1

, which is equal to the stress divided by the modulus of

elasticity. 其瞬时变形为

ε

1

，它等于应力除以弹性模量。If the same stress is kept for a period of

time, an additional strain

ε

2

, 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

ε

2

，

If load is then released, the elastic strain,

ε

1

, 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,

ε

3

, will be left, as shown in Figure 2.5. 最终

会剩下永久塑性应变

ε

3

，如图2.5所示。 In this case

ε

3

=(1

－α

)

ε

2

, where

α

is the ratio of the

recovered creep strain to the total creep strain. 在此情况下，

ε

3

=(1

－α

)

ε

2

,

α

是恢复徐变应

变与总徐变的比值。The ratio

α

ranges between 0.1 and 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

15

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

-6

can 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.

2

Also, creep of 2000 psi- (14N/mm-) strength concrete is about 1.41×10

-6

whereas that of 4000

2

psi- (28N/ mm-) strength concrete is about 0.8×10

-6

per unit stress and length of time. 混凝土强

度和龄期：

t conditions. Creep is reduced with an increase in the humidity of the ambient air.

周围环境条件：

of loading. Creep increases with an increase in the rate of loading when followed by

prolonged loading. 加载速率：

tage 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：

of the concrete mass. Creep decreases with an increase in the size of the tested

specimen. 混凝土尺寸：

, 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：

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

16

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：

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,

C

r

0.13

3

t

, where

C

r

= creep strain per

unit stress per unit length. 对28天龄期加载的普通混凝土，

C

r

0.13

3

t

，

C

r

=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

2. fill

3. peat

4. flexing

n. 夯实，捣紧；tamp, compact

n, vt. 填方；填土

n. 泥煤，泥炭块；Partially carbonized vegetable matter

n. 挠曲；flex, deflect, flexure, flexural

17

5. vegetation

6. poplar

7. shrub

8. seeding

9. pruning

10. pollard

11. desiccation

12. loess

13. sewer

14. coffer

15. piping

16. matrix

17. swallet

18. `subsidence

19. excavation

20. seepage

21. rolling

22. untimbered

n. 植被

n. 白杨

n. 灌木， arbor乔木

n. 树苗，秧苗

n. prune，修剪

vt. 修剪树枝

n. 干燥；desiccate, dry

n. 黄土；loess plateau

n. 下水道，污水管；sewage; drainage

n. 围堰；coffer dam

n. 管涌

n. 胶结材料，矩阵

n. 地下川；溪流入地下的进口

n. settlement; subside, settle

n. 开挖，excavate, cut

n. 渗流，渗透；seep, permeate

n. 碾压，轧制

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,

18

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

19

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 , 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。

20

Effects of Groundwater Lowering地下水位下降的效应

As water is pumped from an excavation, the water table in the surrounding ground may be

lowered. 当从开挖的基坑中将水抽出时，其周围地下水位将会下降。Settlement can result from

this reduction in hydrostatic conditions due to two processes. 由于以下两种过程，这种含水量的

减小会导致沉降。Firstly, in some clays, as discussed above, a decrease in moisture content will

result in a decrease in volume. 其一，如上所述，在一些粘土中，含水量的减小将导致体积减

小，The soil above the reduced groundwater level may therefore shrink. 从而使下降后的地下水

位以上的土收缩；Secondly, a reduction in hydrostatic pore pressure results in an increase of the

effective overburden stress on the layers below. 其二，空隙静水压力的减小导致下层土的有效

覆盖土压应力的增加，Accordingly, the soil (especially in soft clays or peat) beneath the reduced

groundwater level may be consolidated by the increase in effective stress. 从而可能使下降后的

水位以上的土（特别是粘土或泥炭土）发生固结。

Effects of Temperature Changes 温度变化的效应

Quite severe shrinkage can occur in clay soils as they dry out beneath foundations of furnaces,

kilns, ovens and boilers. 当炼钢炉、砖窑、烤炉和锅炉房基础下的粘土变干时，土可出现严

重的收缩。In one case, a boiler building on the London Clay settled 150mm at the center and

75mm at the sides in less than two years. 例如，在不到两年内，一个建造在伦敦粘土的锅炉房

中心沉降了150mm，周边沉降了75mm. It is usual to provide an open or rubble-filled air gap

between such heat sources and the foundation soils. 因此，通过在此类热源和基土之间设置一

敞开的或碎石填充的通气层。

Effects of Seepage and Scouring 渗透和冲刷效应

In certain sandy soils, such as fine dry sands and loess, the movement of water can move some of

the fine particles. 在某些砂土中，如细干砂土或黄土中，水的流动能移走一些细小颗粒。

Scouring is the removal of material by surface water and streams, but this can also occur where

sewers or water mains have been fractured. 冲刷是土被地表水或水流带走的过程，但这在下水

管或供水主管道破裂的地方也可能发生。Where excavations are taken well below groundwater

level within coffer dams and the like, the upward flow of water may cause a form of instability

called piping. 在大大低于地下水位的围堰和类似结构中进行开挖作业时，水的向上运动可能

会导致一种称为管涌的不稳定。In arid areas the same soils are liable to surface erosion due to

wind action. 在干燥地区，此类土可能会因风作用而产生表面侵蚀。

Loss of Lateral Support 失去横向支撑

A common form of foundation movement, often leading to serious, even catastrophic, building

failure is associated with the excavation of deep holes alongside the foundation. 一种常见的、通

常会导致严重的、甚至是灾难性的建筑物破坏的基础运动， 都是由基础周围开挖深孔所致。

21

Many cases have been recorded in which adjacent excavation has resulted in a failure. 有在建筑

物周围进行开挖造成建筑物破坏的许多实例。The bearing capacity of the soil directly beneath a

footing is dependent on the lateral support afforded it by the soil alongside; 基底土的承载力与

其周围土所提供的侧向支撑有关，in calculating the ultimate bearing capacity of the soil this is

taken into account. 从而在计算土的极限承载力时是计入这一影响的。If this lateral support is

removed, as may occur in an untimbered excavation, the likely outcome is a shear slip in the soil

beneath the footing, taking the footing into excavation. 如果移去这一支撑，如在无支撑开挖时

所出现在那样，可能出现的问题就是基础下土发生剪切滑移，从而将基础带入开挖的坑中。

Similarly, settlement might occur as a result of movement of natural earth slopes or cuttings, due

to sliding or flowing. 与之类似，由于土的滑动或流动所引起的自然坡或切坡的运动也可能导

致基础沉降。

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本文标签： 荷载混凝土结构收缩粒径