地质勘查报告 英文
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Bosch (Shanghai) Headquarters
Engineering Geological Detailed
Investigation Report on Plan-built Site
Ⅰ.Preface
1. General Project Situation
It is planned to build Bosch (Shanghai)
Headquarters, which is located in
HongQiao
LinKong Economy Park, by Bosch(China)
Investigation Co.,Ltd. The
plan-built site is
near Xiehe Rd. in west, near linhong Rd. in
north,near Fuquan Rd. in
east and near Zhujia
River in south, The headquarters is 9 floors on
ground and 2 floors
in underground,The total
building area is 77000m
2
,of which the area
of overground is
51000m
2
,the area of
underground is 26000m
2
.
The
project should be designed by
Suzhou Industry
Park Design & Research Institute Co.,Ltd., The
investigation area is
about 14,500 m
2
.
We are consigned to investigate this built site.
Character of Plan-building and Main
Specification
According to design scheme, The
project is planed to use pile foundation, and the
concrete
design requirement is as
follows: Table 1.
The Character of Plan-
building
table1
Data of
foundation
Max load
Building Structure
Calculation
column of per
Basement or
other fixing allowable
name type
floor
type of
Buried
foundation
type
depth
spacing column
foundation（area、size、settlement
（m）
depth） （cm）
Head- Frame shear
-9.0
8.4m
2 floors
According
quarters wall
9
Class b pile ×8.4m 13000KN
basement
to code
remark
The 2 gatehouses is
planed to use shallow foundation(strip
foundation).
According to chapter 3.1 of
National standard Code for investigation of
geotechnical
1
engineering (GB50021-2001),
the importance rank of this project is first, site
rank
second, foundation rank second and
geotechnical engineering investigation rank
second,
so that the investigation rank is
class A.
of Investigation, Main Technical
Criterions and Code
The main technical
standards used in the investigation of this
project are as the
follows:
(1)National
standard Code for investigation of geotechnical
engineering
(GB50021-2001)
(2) National
standard Code for design of building foundation
(GB50007-2002)
(3) National standard Code for
seismic design of buildings (GB50011-2001)
(4)
National standard Soil Engineering test Method
Standard (GBT50123-1999)
(5) National standard
Code for Survey of engineering (GB50026-93)
(6)National standard Enforceability clause for
engineering construction
(structural
architecture part for 2002 edition)
(7)
Industrial standard Rule for multistory building
investigation of geotechnical
engineering(JGJ72-2004)
(8) Industrial
standard Technical Code for building Pile
Foundations(JGJ94-94)
(9) Industrial standard
Technical specification for electrical cone
penetration test
(CECS 04: 88)
(10)
Shanghai project construction specification Code
for investigation of
geotechnical engineering
(DGJ08-37-2002)
(11) Shanghai project
construction specification Code for design of
building
foundation (DGJ08-11-1999)
(12)
Shanghai project construction specification Code
for design of excavation
engineering（DGJ08-61-97）
(13) Shanghai project construction
specification Code for seismic design of
buildings (DGJ08-9-2003)
(14) Shanghai
project construction specification Code for
Geotechnical
Engineering Investigation
Document Authorized Depth (DGJ08-72-98)
(15)
Shanghai project construction specification
Technical code for Ground
Treatment of
buildings (DGJ08-40-94)
(16) Shanghai project
construction specification Site operating
specification for
investigation of
geotechnical engineering (DGTJ08-1001-2004)
According to the above code and the technical
request put forward by the employer
and
designer, some relative specifications and the
features of this project, the aim of this
investigation is to investigate the
geotechnical engineering condition detailed, carry
out
general analysis and appraisal and offer
the geological base for the foundation design.
The main engineering geological problems
needing resolve are detailed as the
following:
(1)Finding out the character of each stratum,
imbed condition and changed
situation within
the scope of the investigation depth (65.00m) in
the site. Offering
foundation soil physical
and mechanical character index of each layer and
in-situ
measurement result.
(2)offering
the design value and eigen value of the bearing
capacity on the nature
foundation; offering
the ultimate bearing resistance typical values and
verticality
bearing resistance design value
,eigenvalue of individual pile and providing
uplift
bearing resistance of uplift pile.
(3)Appraising imbed condition
,
distribution and trait of infection depth for
foundation ditch’s
timbering, and
offering parameter for timbering design and
construction.
(4)Appraising the
feasibility of pile’s construction and the
infection to
surrounding
environment.
putting forward prevention and treatment ways.
(5)Making certain the earthquake basic
intensity and the site sort. Finding the
liquefaction possibility of saturated sandy
silt or sand within the depth scope of 20.0m
in the planned site.
(6)Finding the embed
situation and classification of groundwater and in
the site
and judging whether it is to corrupt
the concrete and subsoil or not;
(7)Finding
whether there is any poor geological phenomenon,
such as hidden
creek, hidden pond and
underground barriers, finding out their
distribution range, depth
and characteristic
of backfill.
(8)Appraising and analyzing the
stability and feasibility of the plan-built site.
,Method of Investigation and Completed
Workload
(1)Layout of workload
According to Code for investigation of
geotechnical engineering，the
prospect
holes are laid like cancellate in this
project, and the boreholes are alternated with
CPT
holes,the space of the prospect holes
is less than 35.0m or 35m,The little holes are
laid
around the foundation ditch,and the space
is from 10.0m to 15.0m.
(2)
Method of
Investigation
In this investigation,
borehole sample, standard penetration test [SPT],
cone
penetration test [CPT],
vane
shear test,
injection test and laboratory
soil test are used.
(2.1).Boring：using
borer(type H-30)with silt slurry encasing to
headway, and
according to the subsoil’s
character, picking off soil samples with
pistontype open
sample quality scale of
samples isⅠtoⅡ.
(2.2).SPT：using drop
hammer(63.5Kg) to test, and the drop height is
76cm. Test
point space is 2.0～3.0m, The SPT is
carried though in silt and sand under
2
blow count of every point should
be noted , and the Particle analysis of disturbed
soil
samples is necessary.
(2.3).CPT：It
is finished with static sounding instrument (type:
SYW-15).The probe is
single-bridge with
15cm
2
(probe no. 3803，calibration
factor:2.8798KPa).It can reflect
soil’s change
in diverse depth. And the CPT data is collected
with instrument (type:
LMC-310).
(2.4).Vane shear test：It is finished with
electromotive vane shear instrument (type:
ZCB-50).The vane
standard is
50cm×100cm，No.983，calibration factor: 0.01157N.m,
testing space is 1m ,And the data is collected
with instrument (type: LMC-310).。
(2.5).Injection test：Insulating non-test with
sleeve, observing water level’s dropping
in
different time after injection, So that the
permeability of associated stratum can be
measured, and the observation time is 2 to 8
hours.
(2.6).Artesian water level
observation：using steel tube(diameter: 50mm) to
survey
the depth of Artesian water in stratum
of ⑤2-1.
(2.7).Little hole：being finished by
manpower helical auger, and each footage is no
more than 0.5m.
(2.8).Soil or water test
in doors：routine test to undisturbed soil and
disturbed soil,and
the special test such as
CU, K
0
,K,Qu are necessary to soil within
the depth scope of
test of UU is finished in
layer ⑧1 because underside of the pile tip is soft
clay.2 sets water samples are adopted in
borehole G3 and G10.
ted Workload
This
field work was carried out from 21th, August, 2007
and ended on first,
September. The position of
prospect holes are measured through its
relatively
relative
position with
landform and landmark, Surveying every hole’s
elevation after field work
test is finished
on 31th, August, 2007, and water partial analysis
is finished
on 28th, August, workload is
as follows:table2
Prospecting Workload
Table2
Item
Workload
Item
Workload
Borehole
65.30m(1),65.00m(5),50.30m(1),
50.00m(3),total footage 590.60m.
W,γ,G 232
CPT
65.00m(4),50.10m(2),50.00m(12),
total footage 960.20m..
Wp , W
L
178
flash hole 23.00m(3),total footage69.0m..
C, Φ 124
vane test 23.00m(3), total
footage69.0m..
labor
a, E 163
Field
Little hole 4.00m(41), total footage 164.0m.
atory
Particle analysis 175
work
SPT time
65
soil
unconfined
compressive strength 13
undisturbed soil
232
test
K
0
13
disturbed
soil
65
CU’ 12
Water sampling
2
sets
UU’ 3
survey
75
KvKh 1718
Water partial analysis 2
5.
Elevation System and Basis of Elevation
Measurement
In this investigation, the
elevations of prospecting points are measured by
the
Bench Mark (No.4-116) of Shanghai, which
is 4.116m in Wusong elevation
system(2006). It
is located at No.6,Zhangjiang ferry, xinjing
town,Changning zone.
Ⅱ Geotechnical
Engineering Condition of Planned Site
1.
Terrain and Geomorphology
This
site is located at the south-east inlet of
Changjiang Delta, its geomorphology
is
littoral plain. The hypsography is mostly
flat. The borehole elevation of measured
points is within the range from 3.35m to
4.16m, and differential elevation is 0.81m.
During investigation, the removal staff is
cleaning up the old foundation,so the part of
the plat isn’t level up,and its elevation only
2.51m.
3
2.
Compositions and
Character of Foundation Soil
In this
investigation, maximum prospecting depth is 65.3m,
and within the scope,
the found foundation
soil belongs to the Quaternary deposit, which is
composed of silty
soil,clay soil and sandy
soil. According to their structural character,
properties and
difference of physical and
mechanical character, the foundation soil can be
divided into
7 layers, see attached table
character of every stratum can be seen in Stratum
Speciality Table and Borehole Log.
Composition of foundation soil
table3
Stratum
No.
Stratum Name
geologic age
genetic type distributing
①1
Filled soil Q
3
4
Filled soil all over
②
Brown yellow
～grey yellow silty clay
Q
3
4
Coastal～bayou
all over，
thin in old foundation
③ Grey mucky silty
clay Q
2
4
Coastal～shallow sea all over
④ Grey mucky clay Q
2
4
Coastal～shallow sea all over
⑤1 Grey mucky
silty clay Q
1
4
Coastal, morass all
over
⑤2-1 Grey clay silt Q
1
4
Coastal, morass all over
⑤2-2 Grey silty clay
Q
1
4
Coastal ,morass all over
⑤2-3
Grey clay silt Q
1
4
Coastal, morass all
over
⑤3 Grey brown silty clay Q
1
4
liman all over
⑤4 Grey green silty clay
Q
1
4
liman all over
⑦ Grey
green～grey silty sand Q
2
3
bayou～Coastal all over
⑧1 Grey silty clay
Q
2
3
Coastal～shallow sea all over
⑧2
Grey silty clay interbed silty
sand
Q
2
3
Coastal～shallow sea No
penetrated
3. Physical and Mechanical
Properties of Foundation Soil
(1) Physical and
Mechanical Properties of Foundation Soil Index
In this investigation, we have deleted some
abnormal values of the physical and
mechanical
of each layer. See Stratum Physical and Mechanical
Properties Parameters
(attached No.2-1),
and the explanations are as follows:
(1.1)The indexes showed in the table are the
maximum, minimum, arithmetic
the design is in
under, statistical parameters should be taken into
consideration according to the safe principle.
(1.2)In the table, friction angle Φ of the
foundation soil and cohesion c are peak
shear
resistance indexes.
(1.3)In the table, static
penetration Ps is mini-mean value.
(1.4)In the
table,the bow count of SPT is measured value.
(2) Foundation Bearing Value
The
foundation bearing eigenvalue is ensured according
to Item 5.2.3 in national
standard Code for
design of building foundation (GB50007-2002) and
Item 13.3.4 in
Shanghai project construction
standard Code for investigation of geotechnical
engineering (DGJ08-37-2002). The design
foundation bearing value is calculated
according to Item 4.2.3 and Item 4.2.4 in
Shanghai project construction standard Code
for design of building foundation
(DGJ08-11-1999), combined with CPT,SPT and
investigation experience. The assumed
condition for design bearing value calculation is:
strip foundation is 1.50m wide and 1.00m
embedded, free water elevation is 0.50m
embedded, the design values (f
d
) and
eigenvalue (f
ak
) of foundation bearing
capacity of
each layer is in detailed in the
table 4.
Foundation bearing design value
(f
d
)
eigenvalue(f
ak
)
table 4
Stratum
No.
Stratum Name
Ps
C , φ(peak)
f
d
f
ak
(MPa)
C(kPa) φ(°)
(Kpa)
(Kpa)
②
Brown yellow～grey yellow silty
clay
0.65 19 21.0
95 75
③
Grey
mucky silty clay
0.59 9 23.0
75 60
④
Grey mucky clay
0.56 11 16.5
70
55
⑤1
Grey mucky silty clay
1.00 14 20.5
90 70
In the above table, value of
f
d
f
ak
is only used for appraising
the character of stratum and comparing the soil
properties. When the design
is in under, it is
calculated on the basis of actual foundation type,
size and embedded depth and considered the
strength and deformation of
the under-
foundation.
4
water
(1) Phreatic
The groundwater in the
planned site is phreatic water. The elevation of
groundwater is controlled by precipitation and
evaporation, and is related with the
Zhujia
rivers nearby. During the investigation, actual
embedded depth of the static water
table is
ranged from 1.40m to 2.10m, and the correspond
water elevation from 1.95m to
2.43m. According
to Shanghai project construction specification
Code for investigation
of geotechnical
engineering, the depth of groundwater table in
Shanghai ranges from
0.50m to 0.70m perennial,
meanwhile low groundwater table may reach 1.50m.
High
groundwater table (0.50m) can be used in
calculating bearing capacity of natural base
and checking computations for antifloatage,and
low groundwater table(1.50m) can be
used in
designing pile and calculating subsicence.
(2)
artesian water
In this
investigation,we gauge the depth of micro artesian
water head in layer ⑤
2-1 by injection
hole(Z1).and know the depth of artesian water head
in layer ⑤2-1 is
6.38m, the corresponded
elevation is -ng to Item 3.2.1 in Shanghai project
construction standard Code for design of
building foundation (DGJ08-11-1999),the
micro
artesian water head and artesian water head are
below phreatic water elevation in
Shanghai,and
the change of water elevation is in cycle,the
depth ranges from 3.0m to
designer can take
water elevation in
disadvantage.
(3)
Corrosiveness of groundwater
In order to
distinguish corrosiveness of groundwater, 2 sets
of the groundwater
samples are taken from
borehole G3, G10. According to the results of
analysis
(attached No.15-1) ,the groundwater
in this planned site is freshwater. According to
the
Shanghai specification code for
investigation of geotechnical engineering,
groundwater,
and subsoil in this site
have no corrosion to concrete, but slight
corrosion to steel
structure.
5
Adverse Geologic Phenomenon
According to
the result of this investigation, the site wasn’t
found any poor
geological phenomenon, such as
hidden creek, hidden pond. Because the old
foundation
be removing ,the depth of some part
of the filled soil is 3.00m.
According to
information be provided by owner,combining with
excavating the old
foundation,we know that the
former Second feedstuff workshop of Shanghai
Xinfeng
Feedstuff Factory lied in the site.
There are some old base slab and pile,and they
should infect the coming construction,So that
attention to designer and construction is
necessary. It can be seen the corrective data
attach to
plan layout and pile layout
about
Second feedstuff workshop of Shanghai
Xinfeng Feedstuff Factory.
6.
Site
Earthquake Effects
(1).Basis condition of
site seismic
design
According to
national standard Construction antiseismic design
standard
（GB50011-2001）and Shanghai project
construction specification Code for seismic
design of buildings (DGJ08-9-2003), this site
belongs to Ⅳ site, Antiseismic design
intensity of the region is Grade 7. Design
basic earthquake acceleration of ground
motion
is 0.01g and design earthquake grouping is
No.1.
Sedimentary veneer depth is
more
than 80m,and equivalence transversal wave is less
than 140ms.
(2)Liquefaction distinguish
The investigation result shows that there
isn’t some bedded sandy silt and sand
within
20m. The planned site isn’t liquefaction even if
antiseismic design intensity of
5
this project is Grade 7.
(3)Antiseismic section divide
According to
item 4.4.1 of national standard Construction
antiseismic design
standard（GB50011-2001）,Most
of the shallow layers is soft soil ,and the site
is
disadvantage antiseismic section.
Ⅲ. Analysis and Appraisal of Geotechnical
Engineering
1. Stability and Feasibility
of Planned Site
There is no liquefacient
soil layer, no active rupture, no landslide and so
on. This
site is stable and suit for
construction.
2. Natural Foundation
The investigation result shows that the layer①
is too soft and not to be bearing
course of
natural foundation. The layer②, its
compressibility from medium to high,
water
content is 33.1%,void ratio is 0.95，and the mean
value PS is 0.65MPa，The soil is
relatively
better. it can be chosen for bearing course of
natural foundation to light
accessory planed
building. The foundation bottom elevation should
be 1.50m. When
Layer ② is used as natural
foundation bearing course, the design
valueeigenvalue is
95kPa75kPa. Designer should
calculate bearing capacity according to
practical situation
and confirm foundation
buried depth with the depth of filled soil.
Foundation
(1)Chosen for pile
foundation bearing course
According to the
requirement of designer, the project will be
planed to chose pile
soil above of the
layer⑤1 in the site is mostly made of soft clay
with
low strength and high compressibility,So
these soils aren’t chosen for pile foundation
bearing course.
The earthiness of
Grey clay silt in Layer⑤2-1 is relatively better
with mean value
PS (3.58MPa),The layer buried
too shallow in the chose it for pile
foundation bearing course,the pile can’t meet
the requirement of design (for short pile
and
small individual pile bearing value). So the layer
isn’t chosen for pile foundation
bearing
course also.
The thickness of Clay in
layer⑤2-2,⑤3,⑤4 is too thin and bedded plane
fluctuation is too big, So these layers aren’t
chosen for pile foundation bearing course
also.
The earthiness of grey clay silt in
Layer⑤2-3 is relatively better ,and its mean
thickness 6.49m,water content 31.6%,void ratio
0.94,compression index 0.24 MPa
-1
and
medium dense. The layer is distributed all
over the site, And the layer top elevation is
from-26.80 to -29.53m, So the layer can be
chosen for pile foundation bearing course.
With high strength ,grey green～grey silty sand
in layer⑦ is distributed all over
the site，and
its mean value PS 11.96MPa,mean thickness
4.95m,water content
22.4%,void ratio
0.70,compression index 0.14 MPa
-1
and with
medium to low dense.
And the layer top
elevation is from -38.50 to - the higher
individual pile
bearing value is required , we
can choose the layer for pile foundation bearing
course.
The layer⑧1 and ⑧2 is mainly compact
layer of pile foundation bearing course.
(2)Chosen for pile type and pile size
When choosing layer ⑤2-3 for pile foundation
bearing course, according to
pile
engineering geologic condition and
circumstance, we can use premoulded pile with
good bearing effect , easy to control quality
of construction and quickly progress. The
pile’s sectional area should be from 350×350mm
to 400×400mm or Φ
400mm(PHC),We also can use
bored pile withΦ choose layer⑦ for pile
foundation bearing course,because layer ⑤2-1
and ⑤2-3 having high strength, We
6
need use PHC with Φ500mm,or bored
pile withΦ750mm to Φ800mm.
(3)Evaluation for
individual pile vertical bearing value.
According to table6.2.4-1 in Shanghai project
construction standard Code for
design of
building foundation (DGJ08-11-1999),combined with
CPT and investigation
experience, The
f
s
and f
p
of premoulded pile,
bored pile is ensured. see attached table 5:
Value of f
s
and f
p
table5
Stratum No. Stratum Name
PS
premoulded pile
bored pile
(Mpa)
fs(kpa) fp(kpa) fs(kpa) fp(kpa)
②
Brown
yellow
～grey yellow silty clay
0.65 15
15
③
Grey mucky silty clay
0.59
15(6m up)
20(6m down)
15(6m up)
16(6m down)
④
Grey mucky clay
0.56 25 20
⑤1
Grey mucky silty clay
1.00 40 30
⑤2-1
Grey clay silt
3.58 50 40
⑤2-2
Grey silty clay
1.97 60 45
⑤2-3
Grey clay silt
5.23 65 2500 50 900
⑤3
Grey brown
silty clay
1.70 60 45
⑤4
Grey green
silty clay
2.15 65 50
⑦
Grey
green～grey silty sand
11.96 95 5000 75 1700
Remark: in the
table,fs2=q
sia
,fp2= q
pa
.
According to the value of f
s
and
f
p
in the above table, assuming that
leveling elevation
of the site is 4.00m,The
individual pile vertical bearing value of diverse
piles are
calculated according to table6.2.4-1
in Shanghai project construction standard Code for
design of building foundation (DGJ08-11-1999),
example for hole C11,
attached table 6:
Estimation of
individual pile vertical bearing value
table6
Base bottom
diameter
bearing
course
Calcul-
Depth of pile
Planned
Leveling or
elevation
depth
Pile
cated
entering into
Pile
Pile
R
building
Elev.
side
Stratum
(m)
type Hole
bearing
tip
Elev.
length
K
R
d
R
a
(kN
(kN) (kN)
(m) (m)
length
Stratum
(mm)
No.
Name
No.
course (m)
)
(m)
(m)
Square 350×350 1750 1090 875
Pile 400×400
Grey clay
PHC φ400
⑤2-3
silt
C11 1.47 -31.00 26.00
2050 1280 1025
1610 1005 805
Head-
quarters
4.00
9.00 -5.00
Bored pile φ600 1760 1100 880
PHC φ500
Grey
3615 2255 1808
φ750
green～
Bored pile
⑦
grey silty
G4 0.85 -41.00 36.00
3810 2380 1905
φ800
sand
4115 2575 2058
remark：the individual pile vertical bearing
value in
the above table don’t consider of
pile stem strength.
The individual pile
vertical bearing value in the above table is
calculated with
assuming condition. After the
pile design scheme is assured, in order to provide
the last
individual pile vertical bearing
value ,the designer can calculate individual pile
bearing
value according to
Value of
f
s
and f
p
(table5)
in this
report and carry out individual pile
vertical
bearing static load test.
(4)
Recommended value of Es
When calculating
pile foundation’s ultimate subsidence, Es under
pile tip is adopted
from dead weight to dead
weight+additional pressure. According to Stratum
Compression Curve Figure(12-1~12-2), CPT ,blow
count,and consider of construction
experience
in Shanghai, Recommended value of Es is offered.
see attached table 7:
Es
under pile tip
table7
Stratum
γ。
Ps N
Soil test
Recommended
No.
Stratum Name
（kNm
3
） (MPa) (blow count )
Es Es
（MPa） （MPa）
⑤2-3
Grey clay silt
17.9 5.23 14.5 20 20
⑤3
Grey brown
silty clay
18.3 1.70 12 12
⑤4
Grey
green silty clay
19.8 2.15 18 18
⑦
Grey green～grey silty sand
19.0 11.96 37.1
40 46
⑧1
Grey silty clay
17.7 1.97 12
12
⑧2
Grey silty clay interbed silty sand
18.5 3.21 14 14
7
pile
According the design requirement,some part of
the 2 floor basement has no building
on
top,and its weight less than buoyance of order to
get over
buoyance,the uplift pile is pile tip
can be embedding into layer⑤2-3,
pile type and
pile size can see attached table 9:
According
to table6.2.7 in Shanghai project construction
standard Code for design
of building
foundation (DGJ08-11-1999) and value of f
s
offered in table5, individual pile
vertical
uplift bearing value is calculated, see attached
table 9:
Estimation of individual pile
vertical uplift bearing value table9
Pile apex face Layer of pile tip
Depth of
diameter Calcul- pile
Planned
Leveling
Pile
building
Elevation
depth
or
cated entering
Pile tip
length
R′
(m)
Elev.
Pile type
(m)
(KN)
d
(m)
(m)
side length
Stratum
Stratum
(mm)
No.
Name
Hole into layer of
Elev.
No. pile tip
(m)
(m)
Square
350×350
basement 4.00 9.00 -5.00
Pile
400×400
⑤2-3
Grey
580
Bored pile φ600
clay
silt
C11 1.47 -31.00 26.00 670
660
remark： the design value calculating by soil
is exceed to the pile stem strength, the pile stem
strength is
availability.
2. To clay
and silt , uplift bearing coefficient :λ=0.6.
3.
To individual pile vertical uplift
bearing,the static load test is feasible
5.
Timbering of
foundation
ditch
The project has 2 floor basement, and
the ditch has big area and depth(the depth is
9.00m,belong to second grade ditch),so that
timbering is necessary. bored pile can be
used
acting as earth-supported structure and deep
mixing pile,and the function is
seepage proof
curtain. The SMW also can be used in er,
horizontal
bracing must be set up in ditch,
The ways can assure safety of ditch construction.
In order to offer counting parameter for ditch
timbering and drainage design, Ccu,
Φcu
K
0
,K,qu, vane shear test and injection
test in infection depth for foundation ditch’s
timbering are offered in the
investigation. see attached table 10:
Parameter for timbering of foundation ditch
table10
Indoors test injection
unconfined
Recomme
compressive strength
CU’
Vane
test
No. Stratum Name
Kv Kh
K
nded
．
Peak
Cmsec
K
qu q′u
K
Ccu φcu Cˊ φˊ
KPa
Cms Cms
Cmsec
KPa KPa
St
KPa º KPa º
Brown yellow
② ～grey
yellow silty 3.90E-07 5.17E-06 3.28E-06 3.00E-06
88 58 1.6 0.47 26 14.7 8 27.3 33.7
clay
③
Grey mucky silty
clay
2.82E-07
3.46E-06 3.84E-06 4.00E-06 37 0.48 4 15.0 1 24.7
28.5
④
Grey mucky clay
2.63E-07
4.96E-06 7.66E-07 4.00E-07 43 0.53 8 12.3 4 22.0
31.5
⑤1
Grey mucky silty
clay
2.33E-07 2.82E-06 1.56E-06 3.00E-06 62 30 2.3
0.51 19 12.7 5 23.0 17.6
These factors should
be considered in ditch timbering design:
(1). The depth of the skirt pipe should be
ensured through contract in technology
and
economy,
checking calculation of the items
such as stability,deform, anti
capsize,anti
gliding for ditch bottom soil.
(2).Considering the connection between ditch
timbering and surrounding building.
ensuring
surrounding building g deep well point or ejection
well point for
hydrometeor before ditch
excavation, making groundwater under ditch bottom
to 0.5
～
1.0m. filly considering infection
of precipitation to surrounding.
(3).In
the scope of ditch,there are
layer
①
,
②
and
③
,and the
ditch bottom lies on
the bottom of
layer
③
.because layer
①
is loose,
easy to collapse, and layer
③
is soft
clay, having the clear character of thixotropy
and rheologic,the strength of layer
③
is
very easy to reduce by momentum effect,So that
when excavating,we must reduce soil’s
disturb
as e of the depth of ditch, soil in bottom of the
ditch will be
some rebound, paying attention
to disadvantage infection to timbering,nearly
built
building, underground line and pile
rip.
(4).There are micro artesian water
in layer
⑤2-1、⑤2-
3 and artesian water in
8
layer
，
and respectively
layer top depth of layer
⑤
2-1,
⑤
2-3
and layer
⑦
is no less
than24.40m,30.30m
and 42.00m
，
according to item 13.3.3 in
Shanghai project
construction standard
Code for investigation of geotechnical
engineering
(DGJ08-37-2002).considering
disadvantage factor, adapting artesian head to
3.0m,Through calculating,layer
⑤
2-1
PczPwy=1.29
＞
1.05,layer
⑤
2-3
PczPwy=1.40
＞
1.05
，
layer
⑦
PczPwy=1.52
＞
1.05
，
So that micro
artesian water in layer
⑤
2 and
artesian water in layer
⑦
don’t occur
boiling of sand to ditch bottom.
(5).The ditch
excavation is too big, the way of symmetry
excavation and fitting
supporting in zoning is
g 200
～
300mm thickness earthwork for
leveling up
by man power, and laying blanket
at the first time. preventing bottom soil to be
disturbed.
(6).Ditch bottom don’t discover
for a long time when excavating,say nothing of
ponding, checking calculation anti buoyance
when hydrometeor is stopped.
(7).Strengthening deformation inspection to
ditch timbering system and out of the
system,
ensuring surrounding building safety and the
construction going on wheels.
In a
word,ditch timbering and earth excavation is
emphases and difficulty in the
project. In
order to ensure ditch construction safety,
construction design should be
compile
carefulness before construction.
feasibility
of pile’s construction and the infection to
surrounding
environment
Because of old
foundation, whatever adopting premoulded pile or
bored pile ,it is
necessary to deal with old
foundation, and keep away from the position of old
foundation.
The planed site is 17.0m away
from Zhujia river in south, 18.00～26.00m away
from Xiehe road in west, 42.0m away from
apartment in the project use
premoulded
pile, properly measure should be taken,such as:
rational circulation,
controlling sinking
speed, digging channel for anti pressing,setting
stress release hole
near the built building
,road,and underground utilities,So that reducing
or avoiding
infection of disadvantage to
surrounding building and underground utilities.
and doing
inspection layer⑤2-3 being chosen
for pile foundation bearing course，pile stem
should penetrate layer⑤2-1 with higher
strength and enter into layer⑤2-3 certain depth
So the resistance is big. If layer ⑦ being
chosen for bearing course ,pile stem should
still penetrate layer⑤2-3, ⑤3 and ⑤4,and the
resistance is bigger. So that in this
project
PHC is appropriate, and before construction, in
order to choose appropriate
hammer weight,
pile cushion,pile strength etc. pile sinkage
testing is the
sinkage is difficult,bored
pile can be chosen.
When adopting bored pile
,finished pile is easy, But should be attention to
quality
control,assuring finishing
hole,clearing hole and impregnate quality,and
blowdown in
site.
Ⅳ.
Conclusions and
Suggestions
(1). This site is stable and
suit for construction.
(2). The layer ② i.e.
brown yellow～grey yellow silty clay is relatively
better, So
that it can be choosen for bearing
course of natural foundation to light accessory
planed
foundation bottom elevation should be
1.50m. When Layer ② is used as
natural
foundation bearing course, the design
valueeigenvalue is er
should calculate bearing
capacity according to
practical situation
and confirm
foundation buried depth with the
depth of filled soil.
(3) According to the
result of this investigation, the site wasn’t
found any poor
geological phenomenon, such as
hidden creek, hidden pond. Because of old
foundation,
it is necessary to deal with old
foundation, and keep away from the position of old
9
foundation.
(4)According
loading and foundation soil,We advice adopting
layer⑤2-3 for
bearing necessary,layer⑦ can be
chose as bearing pile type,pile
length and
pile size can see attached the pile design scheme
is assured, in
order to provide the last
individual pile vertical bearing value ,the
designer can calculate
individual pile bearing
value according to
Value of f
s
and
f
p
(table5)
in this report and carry
out individual pile vertical bearing static
load test.
(5) According the design,some part
of the 2 floor basement has no building on
top,and its weight is less than buoyance of
order to get over
buoyance,the uplift pile is
pile tip can be embedding into layer⑤2-3, pile
type and pile size can see attached table 9,
To individual pile vertical uplift bearing, the
static load test is feasible.
(6) During
the investigation, actual embedded depth of the
static water table is
ranged from 1.40m to
2.10m, High groundwater table (0.50m) can be used
in
calculating bearing capacity of natural
base and checking computations for
antifloatage,and low groundwater table(1.50m)
can be used in designing pile and
calculating
subsicence.
In this investigation,we gauge
the depth of micro artesian water head in layer
⑤
2-1 is 6.38m, ccording to Item 3.2.1 in
Shanghai project construction standard
Code
for
design of building foundation
(DGJ08-11-1999),the micro artesian water head and
artesian water head are below phreatic water
elevation in Shanghai,and the change of
water
elevation is in cycle,the depth ranges from 3.0m
to 11.0m. Through calculating,
the artesian
don’t occur boiling of sand to ditch bottom.
According to the results of analysis ,The
groundwater and subsoil in this site have
no
corrosion to concrete, but slight corrosion to
steel structure.
(7) this site belongs
to Ⅳ site, Antiseismic design intensity of the
region is
Grade 7. Design basic earthquake
acceleration of ground motion is 0.01g and design
earthquake grouping is No.1. The investigation
result shows that there isn’t some
bedded
sandy silt and sand within 20m. The planned site
isn’t liquefaction even if
antiseismic design
intensity of this project is Grade 7.
(8) The
project has 2 floor basement, and the ditch has
big area and depth(the
depth is 9.00m,belong
to second grade ditch),so that timbering is
necessary. bored pile
can be used acting as
earth-supported structure and deep mixing pile,and
the function is
seepage proof curtain. The SMW
also can be used in er, horizontal
bracing
must be set up in ditch, The ways can assure
safety of ditch construction.
Relatively
parameter be attached to table 10.
(9) When
adopting premoulded pile, the resistance is big,
So that PHC and pile
sinking facility with
high-power can be used. Because the building
around the plan site
are in scope of crush
soil effect, prevention measure is necessary. In
order to reduce
noise, static pressure is
preferred.
When adopting bored pile, should be
attention to quality control, assuring finishing
hole, clearing hole and impregnate quality,
and blow down in site.
10
11