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Thủy Lực Và Cơ Học Đất: Soil Mechanics Experiment Report

Ho Chi Minh city University of technology
Programme de Formation d’Ingénieurs d’Excellence au Vietnam

SOIL MECHANICS
EXPERIMENT REPORT

Instructor: Dr. Đỗ Thanh Hải
Ms. Tô Lê Hương
Students: All members of class VP13XDC


Contents
Experiment 1……………………………………..Page 1
Experiment 2……………………………………..Page 6
Experiment 3……………………………………..Page 12
Experiment 4……………………………………..Page 17
Experiment 5……………………………………..Page 22


Experiment1: LABORATORY ANALYSIS GRAIN
SIZE COMPOSITION

SIEVE METHODS (d ≥ 0,074mm - ≠ 200) DEPOSITION METHOD (d < 0,074mm)
I. Purpose:
-Laboratory analysis of particle size (grain size):determine the relative proportion as
a percentage of the different groups in the soil particles.
-Based On grain composition and graded roads to assess the level of uniformity and
gradation;waterproof permanence; select building materials; predict the mechanical
properties change determines the magnitude group of particle size; the distribution and
soil classification.
II. Laboratory instrument:
1. Using the sieve method (d >0.074mm)
-Sieve ministry: sieve cap, sieve, sieve bottoms.

Dry
Sieve

Wash
Sieve

Sieve size /
Number
4” (Sieve size)

Diameter d (mm)

2”

50,8

1”

25,4

3/4”

19,1

1/2”

12,7


3/8”

9,51

#4 (Number)

4,76

#6

3,36

#10

2,00

#20

0,84

#40

0,42

#60

0,25

#100

0,149

101,6

#200
0,074
-Scales (accuracy 1g for large scales; 0,1g for small scales).
1


-Divided land instruments, spoon,pestle, oven (105oC), sifting machines …

2. Using the method of deposition. (d <0.074mm)
-Hydrometer: used to measure the proportion of the solution.
-Two cylinder:
+Cylinder 1 specimen + water (1l)
+Cylinder 2 Water used to wash hydrometer

-Stirrer, stirring rods.
-Thermometer: used to measure temperature changes to correct the experimental results
when the temperature changes Mixed viscosity changes velocity change calibrate.
-Stopwatch, bowl containingspecimen, rubber vase, Na4P2O7, sieve N10.
III.

Sequence experiment :
1. Using the sieve method (d > 0.074mm)
2


-Get the M (g) land after drying and separating rubber particles in baseball, for into the sieve
sieve getting ranked in order descending from the top down, proceed sieve until volume set
on each sieve unchanged (about 10 minutes). Land mass balance on each sieve (or cumulative
weight). Volume of soil were taken as follows:
Fine-grained soils:

100 –200g

Sandy soil:

300 –500g

largest soil particles 3/8”:

1000g

largest soil particles 1/2”:

3kg

largest soil particles 3/4”:

5kg

largest soil particles 1”:

10kg

-After the end of the dry sieve, taking m (g) of land at the bottom of the sieve through the
sieve No.200 lavage until water no longer beads through a sieve No.200 land. Part of the land
is located on the No.200 sieve (No.20, No.40, No.80, No.100, No.140, No.200) .. The land
No.200 pass through the sieve washed in water to be condensed 1000ml also to perform
deposition experiments.
-Land cumulative balance (balance volume of soil from large sieve, sieve followed by small
incremental weight), concentration loss <1%.
2. Using the method of deposition. (d < 0.074mm)
-The soil and water through a sieve No.200 will be condensed and 1000ml also entered
cylinder to perform deposition experiments. Swab sight each solution suspensions (soil +
water) in the cylinder, then drop hydrometer into and read some reading on the hydrometer at
the time of 15 '', 30 ', 45', 1 ', 2' , 4 ', 8', 15 ', 30'.
-Based on the distribution characteristics of soil particles in an aqueous solution to determine
the grain composition.
-When the soil is made up of suspension, the average particle diameter will be about various
different; Large particles will sink faster than smaller particles.
-Deposition method is a method based on the proportion of the Stokes law for welding velocity
of spherical objects dropped in a liquid, depending on the particle diameter, particle density,
density and viscosity of the solution of solution.

3


IV . Results of the experiment :
 Data tables of separator experiment
Total amount A = 1000g
Size of sieve (mm)

Accumulate
retained amount
(g)

% Retained
amount

% permeable
amount

1’’

25.00

0

0

100

3/4’’

19.00

0

0

100

1/2’’

12.50

18

1.8

98.2

3/8’’
N04
N010

9.51
4.76
2.00
Bottom of sieve
Total

69
253.5
446.5
552
998.5

6.9
25.35
44.65
55.2

93.1
74.65
55.35

The number
of sieve

Loss content



1000  998.5
x100%  0.15%  1% (admissible data).
1000

 Data tables of drainage sieve experiment
Amount of drainage sieve soil B = 50g

The
number
of sieve
N020
N040
N0100
N0200

Size of sieve
(mm)

Accumulate
retained
amount(g)

0.841
0.420
0.149
0.074

11.20
12.50
14.60
15.80

% Retained
amount for B

%
permeable
amount
for B

% permeable
amount for all
experimental
model

22.4
25
29.2
31.6

77.6
75
70.8
68.4

43
41.55
39.2
37.9

4


 Data tables of decantation test:

P% 

Gs 1000( Rc  1)
x
x100%
Gs  1
m

Gs  2.68 g / cm3
m( g )  50 g

time (t)

15’’
30’’
45’’
1’
2’
4’
8’
15’
30’

Calib
c

Indicated Temperature
value R
T (oC)

1.0145
1.013
1.01155
1.011
1.01
1.0085

32
32
32
32
32
32.5

0.00375

1.007
1.004
1.001

32.5

0.00375

32.5

0.00375
0.00375

0.0036
0.0036
0.0036
0.0036
0.0036

32.5

Corect
Indicate
d value
Rc

precipi
table
length
Hr
(cm)

Diameter
(mm)

0.11909
0.085841
0.071108
0.061956
0.044334
0.03155

% finer
amount
(P)

% finer
amount for all
experimental
model

57.747619
52.9619048
48.3357143
46.5809524
43.3904762

21.8863
20.0726
18.3192
17.6542
16.445

1.0181
1.0166
1.01515
1.0146
1.0136
1.01225

11.5
11.95
12.3
12.45
12.75

39.0833333

14.8126

1.01075
1.00775
1.00475

13.625 0.022795 34.297619

12.9988
9.37123
5.74365

13.05

14.23
15.05

0.017013 24.7261905
0.012372 15.1547619

Diagram of grading
100
90
80
70
60
50
40
30
20
10
0
100

10

1

0.1

0.01

5


Experiment 2: ATTERBERD LIMITS EXPERIMENT
I. Purpose:
Define Atterberd is determined the plastic limit and the limit semis ; that is to determine
the value of the moisture in the paste and plastic limit, which determines the status and
name of the sticky soil.
𝑤𝑃: plastic limit moisture .
𝑤𝐿: limited moisture flowing.

- determine the plasticity index, IP: IP = WL – WP
=> type of soil: clay, sandy clay, sandy clay soil
IP

<1

1-7

7-17

> 17

The name of
soil

Sand

Cát pha

Sét pha

Sét

- determine liquid indicators, IL :(viscosity B) IL=(W-Wp)/IP
=> The State of the land: malleable plastic sticky liquid, liquid, ...
Type of soil
Sandy clay

Clay

Name and status
Hard
Plastic
Liquid
Hard
Semisolid
soft plastic
plastic liquid
liquid

IL
IL≤ 0
0≤IL≤1
IL>1
IL < 0
0 < IL ≤ 0.25
0.25 < IL ≤ 0.5
0.5 < IL ≤ 0.75
0.75 < IL ≤ 1
IL > 1

6


II. Laboratory instruments:
(For experimental pastes limit)
+ Instruments Casagrande (lifting height cap
demand is 1 cm)
+ Trench cutter
+ The mixing knife, mixing glasses, spoon, sieve
N40 (register 0, 42 mm grains), water, cans of
sample containers, weight (precision 0, 1 g),
drying ...
III. Sequencing experiments:
A) Liquid Limit test :
- Use about 100 g ground through a sieve to N40, mix with enough water.

- Use a putty knife, mixing a land grab about 2/3 of the globe calotte.

7


- Use the cutting knife, divide the land in the globe calotte into 2 equal portions (distance
2mm gap, thickness 8mm).

- Get the globe calotte lifted and fell to hr = 1 cm, velocity v = 2 times/s, count the times of
the fall( N)until the ground in 2 parts of the globe calotte closed.

8


- Get the loosened soil in the globe calotte, put in cans, scales, provides dried samples (24h),
weight dry soil samples; determine humidity, obtained 1 pair (number per rotation, humidity).

- Taking the soil from the globe calotte out, mix well to evaporate, doing the experiment again.
- Doing the same experiment about 3-4 times, determine times of the fall N 𝑖−1 < 25
< 𝑁𝑖
B) Experiment soil plastic limit:
- Taking the rest of soil of the Liquid mimit test, mix well, let the steam off loading.
- Then roll them into stick (use 4 fingertips to roll). When the sticks d = 3mm and star
cracking then weigh, then dry to determine humidity. (If d > 3mm, cracked then add water,
If not, fold then roll).
- Doing the experiment twice in the same time and take the medium, approximation < 2%.

9


IV. RESULTS OF EXPERIMENT.
A) Table 1:

B) RESULTS:
Liquid limit of soil:
WL = 66.4%.
72
71.4549
70

Humidity W%

68

66
64.6583
64

62

60
58.8954
58
15

20

25

30

35

40

number of falling

- Plastic limit. WP = (36.944+35.119)/2 = 36.03%
- Plasticity index : IL = (W - WP)/(WL - WP )=(61.5-36.03)/(66.4-36.03)=0.83
With W = 61.5%.
- Liquid index : IP = WL - WP= 66.4 – 36.03 = 30.37%.
10


C) REASON:
- IP = 30.37% > 17%  it’s a clay.
- 0.75 < IL = 0.83 ≤ 1  it’s a plasticity of clay.
D) COMMENT
-Based on the value of IP and IL. Named and notation the soil ; determine the status of the soil
base on TCVN 9362 2012
-We can classify the land from the experimental results based on a line graph
A straight-line.

11


Exercise 3: COMPACTION TEST OF SOIL
I.











II.

Objective :
For construction of highways, airports, and other structures, it is often necessary to
compact soil to improve its strength.
Objective of Standard Compaction test :
To determine relation between water content and dry density of soil
To determine optimum water content and corresponding maximum dry density for soil
To determine relation between penetration resistance and water content for compacted
soil.
Importance of Standard Compaction test
Compaction increases the shear strength of the soil.
Compaction reduces the voids ratio making it more difficult for water to flow through
soil. This is important if the soil is being used to retain water such as would be
required for an earth dam.
Compaction can prevent the build up of large water pressures that cause soil to liquefy
during earthquakes.
Equipments

 Drying oven
 Weighing balance, accuracy 0,01g.

Standard Proctor Compaction Mold, V = 944cm3
 Standard Proctor Hammer (the height of fall is h = 30,48cm ; Q = 2,5kg).
 IS sieve, N4 4.75 mm.
 Steel straight edge.
 Moisture cans.
 Mixing tools, spoons, trowels, etc.

12


III.

Procedure
1. Obtain about 3 kg of air-dried soil and break the soil lumps.
2. Sieve the soil through a N4 sieve. Collect all the soil specimen passing N4 sieve in a
large pan.
3. Add water to the soil specimen and mix thoroughly.
 Determine the quantity of water added:
0.01𝑚
𝑞=
(𝑤 − 𝑤𝑡 )
1 + 0.01𝑤𝑡 𝑠
with:

q: the quantity of water added (g)
ws: the moisture contend required (%)
wt: the moisture of soil before adding water (%)
m: the weight of soil before adding water ( dry soil)
(ws – wt): the increase of the moisture (about 2-3%)

4. Determine the weight of the Proctor Mold + base plate (not extension). Weigh it to the
nearest 1 gram.
5. Attach the extension to the top of the mold.
6. Pour the moist soil in three equal layers. Compact each layer uniformly with the
hammer 25 times before each additional layer of loose soil is poured. At the end of
the three-layer compaction, the soil should extend slightly above the top of the rim of
the compaction mold.

13


7. Remove the extension carefully. Then, trim excess soil with a straight edge.
8. Determine the weight of the Proctor Mold + base plate + compacted moist soil.
9. Remove the base plate from the mold. Extrude the compacted moist soil cylinder
using a jack.
10. Take a moisture can and determine its mass .
11. From the moist soil extruded in step 9, collect a moist sample in a moisture can
(step 10) and determine the mass of moist soil + can.
12. Place the moisture can with soil in the oven to dry to a constant weight.
13. Break the rest of the soil cylinder by hand and mix with leftover moist soil. Add more
water and mix thoroughly.
14. Repeat steps 6-12. In this process, the weight of the mold + base plate + moist soil
will first increase with the increase in moisture content and then decrease. Continue the
test until at least one successive decreased readings are obtained.
15. The next day, determine the mass of the moisture cans + soil samples (from step 12).

14


IV.

Calculation

DATA SHEET FOR COMPACTION TEST
Observation:

Unit

Data

Ordinal experiment
1

A- Mass of mold,
compacted soil and base
plate of mould and base
B-Mass
V-Volume of mold
Moist unit weight, γ
Serial number of can
A- mass of moisture can
+ moist soil
B- mass of moisture can
+ dry soil
C-Mass of can

g

3692.5

g
cm3
g/cm3

1995.5
944
1.80
1

2

3

3765.5 3862.0
1995.5
944
1.88
2

1995.5
944
1.98
3

4

5

3895.0

3871.5

1995.5
944
2.01
4

1995.5
944
1.99
5

g

156.055 140.783 207.177 128.761 149.637

g

146.357 129.107 185.334 112.638 127.510

g

3.112

3.102

3.142

3.043

3.090

Compaction moisture
content, w

%

6.77

9.27

11.99

14.71

17.78

Dry unit weight, γd

g/cm3

1.69

1.77

1.75

1.69

 Moist unit weight: γ =

1.72

𝐴−𝐵
𝑉

with : A- Mass of mold, compacted soil and base plate
B- Mass of mould and base
V- Volume of mold
 Compaction moisture content: w =

𝐴−𝐵
𝐵−𝐶

× 100%

with : C- Mass of can
 Dry unit weight: γd =

γ
1+0.01𝑤

15


Graph between w and gd
1.78

Dry unit weight, γd (g/cm3)

1.77
1.76
1.75
1.74
1.73
1.72
1.71
1.7
1.69
1.68
0

2

4

6

8

10

12

14

16

18

20

Compaction moisture content w (%)

 Results:
Maximum dry density (from plot):

γdmax ≈ 1.77(g/cm3)

Optimum water content (from plot):

Wopt ≈ 12 %

16


EXPERIMENT 4: DIRECT SHEAR TESTS
I. Experimental purposes:
Direct shear tests to determine the basic characteristics of the soil (mechanical properties;
c, φ), which reviews:
Soil shear strength:
S = σtanφ + c
Load bearing capacity of the ground:

R tc  m ( A b  tc  B h  tc *  D ctc )
A, B, C are coefficients dependent on c, φ.
Aside from c, φ can identify with the other experiments:
+ Unconfined compression test : applied to the soil sticky, simple, direct result, the
destruction would be the weakest.
+ Direct shear test : applies to soil and land left stick, simple, direct result, the destruction
is between 2 horizontal surface of the cutting board cutting boxes are fixed in advance.
+ Compression Triaxial test shall apply to all types of soil, but complex experiments to
complete the targets, with 3 experimental methods; Undrained - Unconsolidated (UU),
Undrained - Consolidated (CU), Drained - Consolidated (CD).
II. Laboratory instruments:
Direct shear box apparatus.
Round knife to create experimental soil
samples: diameter 6,3cm (A = 31.17 cm2),
height 2cm. Gauges horizontal displacement, gauges
horizontal strain; 2 / 1000mm: 1 bar = 0,01
mm - gauges horizontal displacement.
Knife, water bottle, weights to apply
pressure or undisturbed soil sample was
prepared.

17


III. Process of experiment
Firstly, soak the two samples of stone into a water container until they’re saturated.

Use a steel rope to cut the cylinder-shape soil sample that is approximately 3 cm high
Create a experiment sample by pressing down the round knife and whittling around the
sample. Then, whet the surface moothly.
Cover 2 sides of sample with 2 pieces of wet-filter paper.

18


We set the soil sample into the box shear apparatus that is between 2 pieces of filter stones,
lock the bolts carefully.

Set that box into shear machine, set the measurer back to zero, get the bolt out of the shear
machine.

Put the load suitably with loading level.

19


Let the machine cut within velocity of 3mm/min until the sample is destroyed completely,
record the maximum values of shearing stress.

20


IV. Result of experiment and discussion
Sample height
Section
Read-around ratio

Compressive Pressure
(kN/m^2)
50
100
150

2 (cm)
30 (cm2)
1.653 (kN/m2 per div)

Maximum deflection
28.5
46.4
65.9

Shear Stress τ
(kN/m^2)
47.1105
76.6992
108.9327

Perform the data on chart, we have the graph below:

 Prolong the line, it meets vertical exis at C=15.759 kPa is cohension force and

the slope of line is angle of internal friction ϕ=34.290
Discussion:
 We can measure shear resistance of a specific soil thanks to the test
 Graph drawn is linear and similar to theory leant

21


Eperiment 5: Consolidation Compression Test
I. Objective.
Consolidation compression tests are used for determining several parameters, such as
subsidence compression coefficient a, coefficient of volume changes mv, compression
index cc, expansion index cs, coefficient of permeability k, modulus of deformation E,
coefficient of consolidation cv, void ratios for each load level, etc with the purpose of
calculating the deformation (subsidence) of the ground level.
Land subsidence is the process of shrinking pore volume, also known as compression.
Under the impact of external loads, solid particles are folded, leading to the reduction of
pore volume. Hence, land is compressed.
When the land is put under loads, water in the pores in the soil is absorbed and has
tendancy to drain out. By consequence, pore water pressure tends to plunge, leading to
the gradually increase of effective pressure. Once the process of water drainage
completely happens, soil particles will suffer from all of the pressure of external loads.
The phenomenon of soil compression due to the steady water drainage from soil pores is
called consolidation.
II. Instrument
 Consolidation compressor.
 Modeling tools (sharp metal ring with 2cm height and cross-sectional area of
20cm2, trimming tool, steel wire can be used for cutting soft clay samples).
 Stopwatch, loads, scale, drying oven, etc.
III. Experiment steps





Use metal ring and trimming tools for putting sample into shape.
Put sample in the compressor, right between two pieces of pumice.
Balance the lever using water.
Put loads on the lever: 0.25, 0.5, 1, 2, 4,…(kg / cm2) It might take at least 24 hours
for the sample to reach its stable compression state under the pressure of loads.
 Observe and record the figures on the deformation meter for each level of load
after first 15 seconds until the deformation reached its stable state. The times
between each two records double respectively: 30s, 1m, 2m, 4m, 8m, 15m, … 1h,
24h.
 After the stablization of the sample at the last load level, begin to remove loads,
vice versa. Record the figures displayed on the deformation meter.

22


IV. Result and comment
P(kg/cm2)

Δh(mm)

e

0

0

0.88

0.25

0.96

0.5

429.45946

0.001128

973

0.0004841

2104.0777

4.23E-05

22477.778

0.000235

4071.2

0.0002256

4313.75

0.0003384

2899.1667

0.39026

5.09

0.25

0.0027824

0.36676

5.21

0.5

378.63636

0.3583

5.46

1

0.0033088

0.45512

5.55

2

364.58333

0.56792

4.52

4

0.0036096

0.70704

3.32

2

E(KPa)

0.78976

1.84

1

a(1/KPa)

0.40154

5

0.41

CONSOLIDATION CAUSED BY WATER DRAINAGE (e-P)
1
0.9
0.8
0.7

e

0.6
0.5
0.4
0.3
0.2
0.1
0
0

50

100

150

200

250

300

350

400

450

P (KPa)

23


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