《工程地质专业英语》

《工程地质专业英语》教学大纲

课程代码：

课程名称：工程地质专业英语

学时安排：总学时

36

学分：

2

适合专业：工程地质

先修课程：

《大学英语》

，

《工程地质学》

，

《工程岩土学》等

教材：

〈工程地质专业英语〉郑孝玉编，吉林大学校内讲义，

< br>2005

，

7

参考书：

编写人：郑孝玉

?

教学目的和要求

工程地质专业英语是 工程地质专业

4

年级学生的选修课，是在学生学习和掌握了

基础理论课，专业课及大学英语之基础上为培养和提高学生专业英语能力而设置的。

通过讲授和与学生交流为他们灌输一些相关专业词汇，表述方式及科学文献的翻译、

课程写作技巧和规范等。为将来学习和工作储备一些相关知识。

?

课程内容概要

1

．

本课程教学内容

?

The Engineering Properties of Rocks

1

）

Certain index properties of rocks are of particular importance to the engineering, which are defined

below.

Specific gravity

(

G

s

and

G

b

).

G

b

is the specific gravity of the solid mineral material of the rock by

itself.

G

b

is the specific gravity of the complete rock, grain plus voids, with the voids empty except for air.

Both are defined as a weight per unit volume.

Saturation moisture content

(

i

s

). This is the total amount of water present in a rock with the voids full.

The ratio of weight of water to dry weight of rock sample, expressed as a percentage, is the saturation

moisture content (

i

s

).

Moisture content

(

W

). This is the amount of water normally present in the voids of a rock , again

expressed

as

a

percentage

(see

i

s

)

above.

Rocks

are

rarely

saturated

with

water,

thus

in

normal

circumstances w is less than is.

Porosity

(

n

). This is the ratio of volume of voids in a rock total volume of the sample. It is expressed

rock index properties

as a percentage; 10% average, 5% is low and more than 15% is high.

The factors that control the porosity of terrigenous sedimentary rocks and soils are as follows:

(a)

The degree of cementation

(b)

The sorting of the sediment

(c)

The packing of the grains

(d)

The shape of the grains

Water-yielding

capacity.

Not

all

of

the

water

in

a

rock can

be

removed

from

it

by

flow

under

the

force of gravity. Some is held as a film on the surface of the grains by capillary forces.

Permeability

(

k

).

This

is

a

measure

of

the

fluid

conductivity

of

the

rock

for

a

given

hydraulic

gradient.

2

）

basic characteristics of soils

2.1 the nature of soils

The destructive process in the formation of soil from rock may be either physical or chemical. The

physical

process

may

be

erosion

by

the

action

of

wind,

water

or

glaciers,

or

disintegration

caused

by

alternate freezing and thawing m in cracks in the rock.

The chemical process results in changes in the mineral form of the parent rock due to the action of

water (especially if it contains traces of acid or alkali), oxygen and carbon dioxide. Chemical weathering

results in the formation of groups of crystalline particles of colloidal size (<0.002 mm) known as the clay

minerals.

Particle sizes in soils can vary from over 100 mm to less than 0.001 mm. Most types of soil consist

of a graded mixture of particles from two or more size ranges. All clay size particles are not necessarily

clay

mineral

particles:

the

finest

rock

flour

particles

may

be

of

clay

size.

If

clay

mineral

particles

are

present

they

usually

exert

a

considerable

influence

on

the

properties

of

a

soil,

an

influence

out

of

all

proportion to their percentage by weight in the soil.

2.2 particle size analysis

The particle size analysis of a soil sample involves determining the percentage by weight of particles

within the different size ranges. The particle size distribution of a coarse-grained soil can be determined

by

the

method

of

sieving.

The

soil

sample

is

passed

through

a

series

of

standard

test

sieves

having

successively

smaller

mesh

sizes.

The

weight

of

soil

retained

in

each

sieve

is

determined

and

the

cumulative percentage by weight passing each sieve is calculated. If fine- grained particles are present in

the soil, the sample should be treated with a flocculating agent and washed through the sieves.

The particle size distribution of a soil is presented as a curve on a semi-logarithmic plot, the ordinates

being

the

percentage by

weight

of

particles

smaller

than

the

size

given

by

the

abscissa.

The

flatter

the

distribution curve the

larger the range of particle sizes in the soil; the steeper the curve the smaller the

size range. A coarse-grained soil is described as

well graded

if there is no excess of particles in any size

range and if no intermediate sizes are lacking. In general a well graded soil is represented by a smooth,

concave distribution curve. A coarse-grained soil is described as

poorly graded

(a)if particles of both large

and

small

sizes

are

present

but

with

a

relatively

low

proportion

of

particles

of

intermediate

size

(a

gap-graded

soil).

Particle

size

is

represented

on

a

logarithmic

scale

so

that

two

soils

having

the

same

degree

of

uniformity

are

represented

by

curves

of

the

same

shape

regardless

of

their

positions

on

the

particle

size

distribution

plot.

The

particle

size

corresponding

to

any

specified

value

on

the

percentage

smaller scale can be read from the particle size distribution plot.

2.3 plasticity of fine-grained soils

Plasticity is an important characteristic in the case of fine- grained soils, the term plasticity describing

the

ability

of

a

soil

to

undergo

unrecoverable

deformation

at

constant

volume

without

cracking

or

crumbling. Plasticity is due to the presence of clay minerals or organic material.

Mo

-grained soils exist naturally in the plastic state. The upper and lower limits of the

range of water content over which a soil exhibits plastic behaviour are defined as the

liquid limit

(

LL

or

w

L

)

and the

plastic limit

(

PL

or

w

P

) respectively.

2.4 soil compaction

Compaction is the process of increasing the density of a soil by packing the particles closer together

with a reduction in the volume of air: there is no significant change in the volume of water in the soil. In

the construction of fills and embankments, loose soil is placed layers ranging between 75 mm and 450

mm

in

thickness,

each

layer

being

compacted

to

a

specified

standard

by

means

of

rollers,

vibrators

or

rammers.

In

general

the

higher

the

degree

of

compaction

the

higher

will

be

the

shear

strength

and

the

lower will be the compressibility of the soil.

The degree of compaction of a soil is measured in terms of dry density, i.e. the mass of solids

only per unit volume of soil.

The

dry

density

of

a

given

soil

after

compaction

depends

on

the

water

content

and

the

energy

supplied by the compaction equipment (referred to as the compactive effort).

The compaction characteristics of a soil can be assessed by means of standard laboratory tests. After

compaction using one of the three standard methods, the bulk density and water content of the soil are

determined and the dry density calculated. For a given soil the process is repeated at least five times, the

water content of the sample being increased each time. At low values of water content most soils tend to

be stiff and are difficult to compact. As the water content is increased the soil becomes more workable,

facilitating

compaction

and

resulting

in

higher

dry

densities.

At

high

water

contents,

however,

the

dry

density

decreases

with

increasing

water

content,

an

increasing

proportion

of

the

soil

volume

being

occupied by water.

?

In Situ

Testing

1. penetrometers

Penetrometer

test

evolved

from

the

need

to

acquire

data

on

subsurface

soils

which

could

not

be

obtained

by

other

means.

Basically

a

penetrometer

consists

of

a

conical

point

attached

to

a

drive

rod

which is forced into the ground either by hammer blows or by jacking. Hence two types of penetrometer

tests

are

recognized,

the

dynamic

and

the

static.

Both

methods

measure

the

resistance

to

penetration

offered by the soil at any particular depth. Penetration of the cone forces the soil aside, creating a complex

shear failure and thus provides an indirect measure of the

in situ

shear strength of the soil.

Dynamic

penetrometers

were

originally

designed

to

determine

the

relative

density

of

cohesionless

soils but their use has been extended to include the design of pile foundations by determining the load and

the required embedment of piles into the bearing strata.

2

．

shear vane test

Because soft clays, may suffer disturbance when sampled and therefore give unreliable results when

tested

for

strength

in

the

laboratory,

a

vane

test

is

often

used

to

measure

the

in

situ

undrained

shear

strength. Vane tests can be used in clays which have a consistency varying from very soft to firm.

3

．

plate load and jacking tests

Loading tests can be carried out on loading plates. However, just because the ground immediately

beneath a plate is capable of carrying a heavy load without excessive settlement, this does not necessarily

mean that the ground will carry the proposed structural load. This is especially the case where a weaker

horizon occurs at depth but is still within the influence of the bulb of pressure which will be generated by

the structure.

4

．

Pressure tests

Hydrostatic pressure chambers are used to measure the reaction of a rock mass to stress over large

areas, giving values of Young

’

s modulus, elastic recovery, inelastic deformation and creep. The results are

used to evaluate the behaviour of dam foundations and related strain distribution in the structure and to

help estimate the behaviour of pressure tunnel linings. Hydrostatic chambers cover a much larger surface

area than other test methods and so provide better results of mass behaviour. However, because of their

cost these tests are used sparingly. A dilatometer can be used in a borehole to obtain data relating to the

deformability of a rock mass. These instruments range up to about 300 mm in diameter and over 1 m in

length and can exert pressures of up to 20 MN/m

2

on the borehole walls.

5

．

In situ

shear test

In an

in situ

shear test a block of rock is sheared from the rock surface whilst a horizontal jack exerts

a

vertical

load.

It

is

advantageous

to

make

the

tests

inside

galleries,

where

reactions

for

the

jacks

are

readily available. The

tests are performed at various normal

loads and give an estimate of the angle of

shearing resistance and cohesion of the rock.

In situ

shear tests are usually performed on blocks, 700

×

700 mm, cut in the rock. These tests can be made on the same rock where it shows different degrees of

alteration and along different directions according to the discontinuity pattern. The factor of safety against

strain due to sliding may depend on a limited zone and it is therefore essential to find and investigate the

weakest

zones.

It

is

sometimes

difficult

to

obtain

sufficiently

undisturbed,

as

in

the

case

of

shales,

to

perform tests. This is also the case when the rocks are affected by residual stresses.

?

Consolidation Theory

Consolidation is the gradual reduction in volume of a fully saturated soil of low permeability due to

drainage of some of the pore water, the process continuing until the excess pore water pressure set up by

an

increase

in

total

stress

has

completely

dissipated:

the

simplest

case

is

that

of

one-dimensional

consolidation, in which a condition of zero lateral strain is implicit. The process of swelling, the reverse of

consolidation, is the gradual increase in volume of a soil under negative excess pore water pressure.

1

．

the oedometer test

The characteristics of a soil during one-dimensional consolidation or swelling can be determined by

means of the oedometer test. The test procedure has been standardized in Standards which specifies that

the oedometer shall be of the fixed ring type. The void ratio at the end of each increment period can be

calculated from the dial gauge readings and either the water content or dry weight of the specimen at the

end of the test.

2

．

compressibility characteristics

Typical plots of void ratio (

e

) after consolidation, against effective stress (

σ

/

) for a saturated clay are

shown that an initial compression followed by expansion and recompression. The shapes of the curves are

related to the stress history of the clay.