土建英语作业(中英文对照翻译)

Foundations

All

structures

designed

to

be

supported

by

the

earth,

including

buindings, bridges, earth fills, earth and rock and concrete dams,consist

of

two

parts.

These

are

the

superstructure,

or

upper

part,

and

the

substructure

element

which

interfaces

the

superstructure

and supporting

ground. In the case of earth fills and dams, there is often not a clear line

of

demarcation

between

the

superstructure

and

substructure.

The

foundation can be defined as the substructure and that adjacent zone of

soil and rock which will be affected by both the substructure element and

its loads.

The foundation engineer is that person who by reason of experience

and training can be produce solutions for design problems involving this

part of the engineered system. In this context,foundation engineering can

be

defined

as

the

science

and

art

of

applying

the

principles

of

soil

and

structural

mechanics

together

with

engineering

judgement

to

solve

the

interfacing

foundation

engineer

is

concerned

directly

with

the

structural

members

which

affect

the

transfer

of

load

from

the

superstructure

to

the

soil

such

that

the

resulting

soil

stability

and

estimated

deformations

are

the

design

geometry

and

location of the substructure element often have an effect on how the soil

responds,the foundation engineer must be reasonably versed in structural

design.

Foundations

for

structures

such

as

buildings,

from

the

smallest

residential

to

the

tallest

high- rise,

and

bridges

are

for

the

purpose

of

transmitting the superstructure load. These loads come from column-type

members with stress intensities rangeing from perhaps 140MPa for steel

to 10MPa for concrete to the supporting capacity of the soil, which

is

seldom over 500kPa but more often on the order of 200 to 250kPa.

Almost any reasonable structure can be built and safely supported if

there

is

unlimited

unately,

in

the

real

situation

this

is

seldom, if ever, the case, and the foundation engineer has the dilemma of

making a decision under much less than the ideal condition, Also, even

though the mistake may be buried, the results

from the error are not and

can

show

up

relatively

soon-and

probably

before

any

statute

of

limitations expires. These are reported cases where the foundation defects

have

shown

up

either

during

construction

of

superstructure

or

immediately thereafter.

Since the superstructure is buried, or is beneath the superstructure, in

such

a

configuration

that

access

will

be

difficult,

should

foundation

inadequacies

develop

after

the

superstructure

is

in

place;

it

is

common

practice

to

be

conservative.

A

one

or

two

percent

over

design,

in

these

areas

produces

a

larger

potential

investment

return

than

in

the

superstructure.

The designer is always faced with the question of what constitutes a

safe

,

economical

design

while

simultaneously

contending

with

the

inevitable

natural

soil

heterogeneity

at

a

site.

Nowadays

that

problem

may

be

compounded

by

land

scarcity

requiring

reclamation

of

areas

which

have

been

used

as

sanitary

landfills,

garbage

dumps,

or

even

hazardous

waste

disposal

areas.

Still

another

complicating

factor is that

the

act

of

construction

can

alter

the

soil

properties

considerably

from

those used in the initial analyse of the factors result in

foundation

design

becoming

so

subjective

and

difficult

to

quantify

that

two design firms might come up with completely different designs which

would

perform

equally

satisfactory.

Cost

would

likely

be

the

distinguishable feature for the preferred design.

This

problem

and

the

widely

differing

solutions

would

depend,

for

example, on the folling.

1)What

constitutes

satisfactory

and

tolerable settlement

;

how

much

extra could, or should , be spent to reduce estimated settlements from say

30 to 15mm?

2)Has the client been willing to authorize an adequate soil exploration

program?what kind of soil variability did the soil borings indicate?Would

additional borings actually improve the foundation recommendations?

3)Can the buildings be supported by the soil using?

4)What are the consequences of a foundation failure in term of public

safety?

What

is

the

likelihood

of

a

lawsuit

if

the

foundation

does

not

perform adequately?

5)Is sufficient money available for the foundation? It is not unheard of

that

the

foundation

alone

would

cost

so

much

that

the

project

is

not

economically feasible. It may be necessary to abandon the site in favor of

one where foundation costs are affordable?

6)What

is

the

ability

of

the

local

construction

force

?

It

is

hardly

sensible to design an elaborate foundation if no one can built it, or if it is

so

different

in

design

that

the

contractor

includes

a

large

factor in the bid.

7)What

is

the

engineering

ability

of

the

foundation

engineer?

While

this

factor

is

listed

last,this

is

not

of

least

importance

in

economical

design. Obviously engineers have different levels of capability just as in

other

professions

and

in

the

trades

such

as

carpenters,

electricians

,and

painters.

If the foundation fails because of any cost shaving, the client tends to

be

quickly

lose

appreciation

for

the

temporary

financial

benefit

which

accrued. At this point , facing heavy damages and a lawsuit, the client is

probably in the poorest mental state of all the involved parties. Thus, one

should

always

bear

in

mind

that

absolute

dollar

economics

may

not

produce good foundation engineering.

The foundation engineer must look at the entire system,the building

purpose,

probable

service-life

loading,

type

of

framing,

soil

profile,