浅层软土地基快速动力固结技术

欢迎各位领导和专家莅临指导WEL

COME2014

-11

-7浅层软土地基快速动力固结技术L

ow

energy

dynamic

consolidation

combinedwith

light

well-point

dewatering同济大学地基基础研究所

Institute

of

Soil

FoundationTongji

University2014

-11

-7概述Intr

oduction

This

method

is

applicable

to

sandy

soil,

sandy

silt,miscellaneous

fill,

etc.,

the

coefficient

ofpermeability

of

which

is

relatively

high(thecoefficient

of

permeability,

ko

,is

larger

than

10-5).2014

-11

-72014

-11

-72低能量强夯法结合轻型井点降水Low

energy

dynamicconsolidationCombined

w

ith

lightw

ell-point

dew

atering1.组合方案。是常规强夯法的一种改进，体现较高的技术含金量。It

is

anconventionalimproveddynamicmethod,technicalconsolidationhaving

highercontent.90

元/m290

yuan

persquaremeterreinforcedarea1.施工人员、机具进出场费约4万元。Costs

of

builders,machines

andtools,

in

and

outconstruc

tion

s

iteare

about

40,000建议方案（以不完全破坏土体结构强度，不形成橡皮土为前题，主动排水，先轻后重，少击多遍）(The

e

ne

rgy

islesser

than

tha

t

ma

yfully

destroystruc

ture,soilwithactive

dewatering

)2.承载力和不均匀沉降控制能满足设计要求Bearing

capacity

andcontrol

of

non-uniformsettlement

can

meet

theneed

of

design

demands.3.计划工期30

天左右Proposed

projec

t

time

limitis

about

30

days.（

notincludingcost

off

ly-ash

w

ith60cmthickness）yuan.2.施工用水、电源由甲方接到工地。Water

and

pow

ersupply

used

inconstruc

tion

s

ite

isprovided

by

PartA.2014

-11

-7低能量强夯法结合轻型井点降水施工方案L

ow

energy

dynamic

consolidation

combined

with

lightwell-point

dewatering

1.

加固效果和工期Reinforcing

Effect

and

Constructionperiod

2．低能量强夯法的加固原理reinforcement

mechanismof

low

energy

dynamic

consolidation

3．施工方案construction

scheme1）.施工降水dewatering2）.夯击工艺参数tamping

parameters

and

technique3）.低能量强夯设备equipment

for

low

energy

DCM4）.收锤参考标准tamping-stop

standard5）.检测和信息化施工monitor

and

information

construction6）.施工程序和步骤construction

procedures

and

steps4.

已成功的大面积施工中应用实例case

history2014

-11

-71.

加固效果和工效Reinforcing

Effect

and

Construction

Efficiency

加固效果(Reinforcing

Effect)In

sandy

soils,

the

SPT

blow

count,

N63.5,

can

reach

to12~15;

the

CPT

value

can

reach

to

5~8Mpa

and

the

PLTbearing

capacity

to

150~200Kpa.

加固深度(treatment

depth)4-6m

工效Construction

Efficiency一个月大约能施工100，000

m2

，About

100,000

m2

canbe

finished

in

one

month.2014

-11

-72．低能量强夯法的加固原理Reinforcement

mechanism

of

low

energy

dynamicconsolidationFig.

2表

2

低能量强夯法联合降水和传统强夯法对比表Low

energy

dynamic

cons

olidation

combined

w

ithlightw

ell-point

dew

atering

andtraditional

dynamic

cons

olidation低能量强夯法联合降水法Low

energy

dynamic

consolidation

combinedw

ithlight

w

ell-point

dew

atering传统强夯法

traditional

dynamicconsolidation机理

Mechanism以不完全破坏土体结构强度为前题，根据土体强度提高情况，逐步增加能量的动力固结。Dynamic

consolidation

by

mean

of

light

w

ell-point

dew

atering

and

impact

energy,

w

hich

isles

ser

than

that

may

fully

destroy

soil

s

tructureand

increases

gradually

based

on

the

soilconsolidation

degree

and

improved

s

trength.大能量和能量积聚的动力固结dynamic

compaction

byhigh

impact

energy夯击方法

Tamping先轻后重，少击多遍The

applied

energy

increases

gradually

incombination

w

ithles

s

blow

count

and

more

pass重锤多击high

ram

energy,

multi-blow

count排水方法

Drainage采用井点降水等主动排水法，同时使土体中形成微裂缝排水。Apply

active

dew

atering

method,

meantime

drainby

mean

of

micro-fissure

in

the

soil

generated

byimpact

energy通常靠砂土自身渗透性

drain

by

soil

its

e

lf2014

-11

-7能量控制Energy

control①激发土体孔压，并使土体产生微裂缝，但又不完全破坏土体结构强度，不形成橡皮土；①

In

orderto

avoid

the

occurrenc

e

of

“rubbery

soil”,

The

applied

energy,

w

hich

generates

excess

w

ater

press

ure

and

micro-fissure

in

soil,

should

beles

s

than

that

may

fully

destroy

soil

s

tructure②先轻后重，少击多遍，从上至下，逐步增大加固深度与范围。②

The

applied

energy

increases

gradually

in靠控制夯击能增大影响深度increase

reinforced

depththrough

higher

tamp

energycombined

w

ith

les

s

blow

count

and

more

pass.

Increase

reinforced

depth

and

area

through

enhancing

the

tamp

energy

gradually.2014

-11

-7附加设施

Equipmentadditional有关主动排水设施。Drainage

equipment

involved通常无

none高透水性、无结构性土，各种土体，包括低透水性、结构性强的软土或埋藏不深（6

～8m

以内），运用范围S

oils

suitable者结构已扰动的软土层。Any

kinds

of

soil,

including

soft

clay

w

ith

low

permeability

and

high

s

tructure

or

dis

turbed

soft

clay浅层加固。S

oil

w

ith

highpermeabilityand

no

s

tructure,

low

erembedded

depth

(6~8m)，shallow

improvement3．施工方案Construction

plan2014

-11

-71）.施工降水de

wa

t

er

i

ng

场地降水采用真空强排水(well-point

dewatering)，在地下水位降至地面下

2.5m(underground

water

dewatered

to

2.5m

below

ground

surface)以下时开始进行第一遍强夯(first

pass)。。

每遍强夯后进行强排水dewatering

after

each

tamping

pass2014

-11

-73）.低能量强夯设备equipment

for

low

energy

DCM

履带式吊车(25t

capacity

track

crane)，夯锤质量(tamper

weight)10~12t，锤底直径

(diameter

of

the

tamper

bottom)2.5m~3m

套轻型井点降水设备light

well-point

dewatering

equipment2014

-11

-74）.夯击工艺参数tamping

parameters

and

technique3

.5

m4.0m3

.5

m4.0m30m3

0

m2014

-11

-75）.收锤参考标准tamping-stop

standard

（1）夯坑周围出现明显隆起和侧向位移

generate

apparent

heave

or

lateral

displacement;

（2）后一击夯沉量大于前一夯沉量crater

caused

bythe

latter

pounding

is

larger

than

the

former

pounding

（3）当夯坑深度≥80cm时。Crater

depth

is

more

than(or

equal

to)80cm2014

-11

-76）.检测与信息化施工monitor

and

information

construction（1）检测内容monitor

content

a．沉降观测settlement

measure

b．静力触探试验CPT

test

c．孔隙水压力观测water

pressure

monitor

d．地下水位观测ground

water

monitor2014

-11

-7

（2）信息化施工information

construction

a.降水的信息化施工information

construction

for

dewatering

i出水量控制discharge

control

ii地下水位监控water

level

monitor

and

control

iii静力触探检测CPT

test

根据以上项目的测试结果，动态调整抽水时间、井点管排距、每遍夯击间隔时间等施工参数。Based

on

the

monitoring

result

of

theabove-mentioned

items,

adjust

the

pumping

time,row

spacing

of

the

well

pipe,

time

interval

of

each2014

-11

-7

pass,

etc.b.低能量强夯效果的信息化施工informationconstruction

for

improvement

effect

I地下水位和孔隙水压力监控water

levelmonitor

and

control

as

well

as

water

pressure

ii静力触探检测CPT

test

iii沉降观测settlement

measure

根据以上项目的测试结果，动态调整夯击能量、夯击间距、每遍夯击间隔时间等施工参数。

Based

on

the

monitoring

result

of

the

above-mensioned

items,

adjust

the

tamping

energy,spacing

of

tamping

points,

time

interval

of

eachpass,

etc2014

-11

-77）.施工程序和步骤construction

procedures

and

steps

1.平整场区，布设强排水管线，并在施工场地四周挖设明沟。Level

the

site,install

well-point

pipes,and

digwater

furrow

around

the

construction

site

2.预埋孔隙水压力计和水位管。Embed

piezometers

andwater

level

pipes

3.降水dewatering：夯击前地下水位排至吹砂面下2.5m以下。Drain

until

the

water

level

lowers

to

2.5m

belowthe

ground

before

tamping

4.测定地面沉降、孔隙水压力和地下水位的初始读数,采用信息化施工法,调整抽水参数.measure

the

originalsettlement,water

pressure

and

water

level,adjusteddewatering

parameter2014

-11

-7

5.夯击tamping：按上述夯击工艺进行夯击，每遍夯后，进行地面沉降、孔隙水压力、地下水位观测和静力触探测试,必须采用信息化施工法，Must

conductinformation

construction

based

on

the

above-mentionedtamping

parameters

and

technique.

6.相邻两遍夯击间歇时间暂定为7～14天，具体应根据孔压消散情况确定。Predetermined

time

interval

of

eachpass

is

7d~14d,which

could

be

adjusted

based

on

thedissipation

of

water

pressure

7.推平和适当碾压level

and

roll

8.强夯施工结束后15天和30天，进行静力触探检测

conduct

CPT

test

after

15d

and

30d

of

tamping

end2014

-11

-7表 低能量强夯联合降水施工工期Fig.

Construction

period

for

low

energy

DC

combined

with

dewatering时间（30

天）time(30d)内容1

2

3

4

5填粉煤灰f

ill

flyash井点降水dewatering低能量强夯

tamping井点降水

dewatering低能量强夯

tamping井点降水dewatering碾

压rolling2014

-11

-74.

已成功的大面积施工中应用实例

（1）上海港外高桥港区四期工程地基处理

上海港外四期C2区和B区（60多万平方米,表层

1-2m为吹填砂,以下为淤泥质土）软基处理采用低能量强夯施工方法，获得成功，己通过由上海市科委组织的专家组通鉴定，认为达到国际先进水平，目前正在申报上海市科技成果。

Soft

soil

improvement

of

C2

area

and

B

area

ofWaigaoqiao

4’Project

of

Shanghai

TerminalContainer(more

than

600

thousand

m2,

hydraulicsand

1~2m,

very

soft

clay

underlying)

isconstructed

by

applying

the

low

energy

Dynamicconsolidation

method

combined

with

well-pointdewatering.

The

improved

effect

is

significant

andconstruction

has

gained

success2014

-11

-72014

-11

-72014

-11

-72014

-11