EAA304/2 GEOTECHNICAL LABORATORY

Transcription

1 GEOTECHNICAL LABORATORY SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA EAA304/2 GEOTECHNICAL LABORATORY No Laboratory Test G1 Direct Shear Test G2 Unconfined Compression Test G3 Consolidation Test ( Oedometer ) G4 Triaxial Test 1

2 Gl - DIRECT SHEAR TEST The term shear strength that is applied in soil is not a fundamental property of a soil as what compressive strength is to a concrete. On contrary, shear strength is related to the conditions prevailing in-situ and can vary with time. The value easured in the laboratory is likewise dependent upon the condition imposed during the test and in some instances upon the duration of the test. The aspect of shear strength test that is dealt with in this laboratory class will be the shear resistance of free-draining noncohesive soils (i.e sands and gravels), which is virtually independent of time. The direct shear test is used to determine the shear strength of soils on predetermined failure surface. The shear box test used in this class is the simplest and the most straightforward method in measuring the 'immediate' or short-term shear strength of soils in terms of total stresses. Although it has a number of shortcomings, but still it is the easiest test to understand. The principles of the direct shear test have been discussed in the previous lecture in EAG345 and should be familiarized by each student before the test start. Objective To determine the shearing strength of the soil using the direct shear apparatus. Scope In many engineering problems such as design of foundation, retaining walls, slab bridges, pipes, sheet piling, the value of the angle of internal friction and cohesion of the soil involved are required for the design. Direct shear test is used to predict these parameters quickly. The laboratory report covers the laboratory procedures for determining these values for cohesionless soils. Apparatus 1. Direct shear box apparatus 2. Loading frame (motor attached). 3. Dial gauge. 4. Proving ring. 5. Tamper. 6. Straight edge. 7. Balance to weigh up to 200 mg. 8. Aluminum container. 9. Spatula. Knowledge of Equipment Strain controlled direct shear machine consists of shear box, soil container, loading unit, proving ring, dial gauge to measure shear deformation and volume changes. A two piece square shear box is one type of soil container used. A proving ring is used to indicate the shear load taken by the soil initiated in the shearing plane. 2

3 Procedures 1. Determine the counterweight that will be used during the test. 2. Check the inner dimension of the soil container. 3. Put the parts of the soil container together. 4. Calculate thelvolume of the container. Weigh the container. 5. Place the soil in smooth.layers (approximately 10 mm thick). If a dense sample. is desired tamp the soil. 6. Weigh the soil container, the difference of these two is the weight of the soil. Calculate the density of the soil. 7. Make the surface of the soil plane. 8. Put the upper grating on stone and loading block on top of soil. 9. Measure the thickness of soil specimen. Put the top 10. Apply the desired normal load. In this case, let say 10kg. 11. Remove the shear pin. 12. Attach the dial gauge which measures the change of volume. 13. Record the initial reading of the dial gauge and calibration values. 14. Before proceeding to test check all adjustments to see that there is no connection between two parts except sand/soil. 15. Start the motor. Take the reading of the shear force and record the reading. 16. Take volume change readings till failure. 17. Add 5 kg normal stress 0.5 kg/cm2 and continue the experiment till failure 18. Record carefully all the readings. Set the dial gauges zero, before starting the experiment 3

4 Results (Please paste/copy this inside your report) From table, plot these graphs: 1. Shear Stress 't (kn/m 2 ) versus horizontal/shear displacement (mm) for each normal load imposed. From this graph, please state the following values: Number of Norrmal load Normal Stress Ultimate shear stress specimens kn/m 2 (at failure ). 2. Vertical/normal displacement (mm) versus horizontal/shear displacement (mm) for each normal load imposed. 3. Ultimate shear stress (kn/m 2 ) versus normal shear stress (kn/m 2 ) for each normal load imposed. From the number (3) graph, determine the shear strength parameter Internal friction angle, Ф= Cohesion value, c= Shear Stress vs Normal Stress Shear Stress Normal Stress 4

5 GEOTECHNICAL LABORATORY SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G1 : DIRECT SHEAR TEST Group No. Sample No. of Testing : Soil sample: Data to Obtain Sample Density if not an Undisturbed Sample Initial mass container = g Final mass container + soil = g Mass of soil used : g Shear specimen data Sample Dimensions; Side : cm Wet Density : g/cm 3 Height : cm Dry Density : g/cm 3 Sade * side Area : cm 2 Moisture content : % Area * height Volume : cm 3 Sample 1 10 kg loading Weight of loading box: kg Normal Load : kg Loading rate : mm/min Normal stress: kpa Load ring const. LRC: N/div. Vert. Vert. Horiz. Horiz. Load Horiz. Shear dial displace dial displace dail shear stress reading V1 reading H1 reading force kpa ( ) ( ) 5*LRC (6/A) Tested by Checked by 5

6 GEOTECHNICAL LABORATORY SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G1 : DIRECT SHEAR TEST Group No. Sample No. of Testing : Soil sample: Data to Obtain Sample Density if not an Undisturbed Sample Initial mass container = g Final mass container + soil = g Mass of soil used : g Shear specimen data Sample Dimensions; Side : cm Wet Density : g/cm 3 Height : cm Dry Density : g/cm 3 Sade * side Area : cm 2 Moisture content : % Area * height Volume : cm 3 Sample 1 20 kg loading Weight of loading box: kg Normal Load : kg Loading rate : mm/min Normal stress: kpa Load ring const. LRC: N/div. Vert. Vert. Horiz. Horiz. Load Horiz. Shear dial displace dial displace dail shear stress reading V1 reading H1 reading force kpa ( ) ( ) 5*LRC (6/A) Tested by Checked by 6

7 GEOTECHNICAL LABORATORY SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G1 : DIRECT SHEAR TEST Group No. Sample No. of Testing : Soil sample: Data to Obtain Sample Density if not an Undisturbed Sample Initial mass container = g Final mass container + soil = g Mass of soil used : g Shear specimen data Sample Dimensions; Side : cm Wet Density : g/cm 3 Height : cm Dry Density : g/cm 3 Sade * side Area : cm 2 Moisture content : % Area * height Volume : cm 3 Sample 1 40 kg loading Weight of loading box: kg Normal Load : kg Loading rate : mm/min Normal stress: kpa Load ring const. LRC: N/div. Vert. Vert. Horiz. Horiz. Load Horiz. Shear dial displace dial displace dail shear stress reading V1 reading H1 reading force kpa ( ) ( ) 5*LRC (6/A) Tested by Checked by 7

8 G2 - UNCONFINED COMPRESSION TEST The primary purpose of this test is to determine the unconfined compressive strength, which is then used to calculate the unconsolidated undrained shear strength of the clay under unconfined conditions. According to the ASTM standard, the unconfined compressive strength (qu) is defined as the compressive stress at which an unconfined cylindrical specimen of soil will fail in a simple compression test. In addition, in this test method, the unconfined compressive strength is taken as the maximum load attained per unit area, or the load per unit area at 15% axial strain, whichever occurs first during the performance of a test. Significance For soils, the undrained shear strength (su) is necessary for the determination of the bearing capacity of foundations, dams, etc. The undrained shear strength (su) of clays is commonly determined from an unconfined compression test. The undrained shear strength (su) of a cohesive soil is equal to one-halfthe unconfined compressive strength (qu) when the soil is under the f = 0 condition (f = the angle of internal friction). The most critical condition for the soil usually occurs immediately after construction, which represents undrained conditions, when the undrained shear strength is basically equal to the cohesion (c). This is expressed as: S u = c= q u 2 Then, as time passes, the pore water in the soil slowly dissipates, and the intergranular stress increases, so that the drained shear strength (s), given by S = C + σ tanø must be used. Where σ = inter-granular pressure acting perpendicular to the shear plane; and σ = (σ - u), σ = total pressure, and u = pore water pressure; c' and φ' are drained shear strength parameters. The determination of drained shear strength parameters is given in different experiment. In this test, a cylindrical specimen, usually 38mm diameter x 76mm height is compressed without any restrain/ confining pressure. The cross section area for the specimen increases with strain with decrease in length. Assume that initial area is, Ao, corrected area for soil sample A, can be determine through this formula. Given A 0 = Initial area ε = Strain = Δ l l 0 Δ l l 0 A=A 0 [1] l-e = Initial length of soil sample = Difference in length of soil sample Unconfined compressive strength for a soil sample q μ is given by 8

9 q μ = P [2] A With P = Axial load during failure, and A = Corrected area for soil sample at yielding during failure For normal soils, if Фis a shear resistance angle, q μ = 2c tan( 45 + Ф ) [3] 2 For clayey soil, if Ф = 0 under undrained condition, so q μ = 2c = P [4] A therefore, 1 Undrained shear strength = C = C u = 1 q μ [5] 2 The soil specimen used during test can be used again to get the same sample with the same dry density and moisture content. This sample can be used again (remolded) to determine the unconfined shear strength. Consistency can be defined as ratio of shear strength of an unconfined soil sample to remolded sample. Apparatus 1. Unconfined compression test apparatus 2. Sampling tube 3. Weigh apparatus 4. Oven 5. Evaporation plate 6. Empty tin (for moisture content determination) 7. Scale and spatula Sample preparation (Undisturbed sample) 1. Sampling tube is inserted into a clayey soil sample. Tube is taken out together with the soil sample. 2. Oil is glazed in the separation mould. Weigh and determine the weight of separation mould. 3. Soil is pushed out from the tube into the separation mould using soil pusher. 4. The sample is cut and put the end of soil sample along the end of separation mould. The extra of soil sample is kept to measure the moisture content of the soil. 9

10 5. Soil sample is weigh together with the separation mould to determine the weigh of soil sample. Procedures 1. Measurement of length and diameter of soil specimen is taken. 2. Measure the exact diameter of the top of the specimen at three locations 120 apart, and then make the same measurements on the bottom of the specimen. Average the measurements and record the average as the diameter on the data sheet. 3. Carefully place the specimen in the compression device and center it on the bottom plate. Adjust the device so that the upper plate just makes contact with the specimen and set the load and deformation dials to zero. 4. Load is applied so that the device produces an axial strain at a rate of 5% per minute, and then the load and deformation dial readings are recorded on the data sheet at every millimeter difference/contrast on deformation the dial. 5. Test is continued until the load dial gauge decreases after experiencing one significant maximum value or when a horizontal difference/contrast amounting 16mm whichever happen earlier. 6. Draw a sketch to depict the sample failure. 7. If the shear plane is significant, angle between failure surface and horizontal surface can be determined. 8. Soil sample after failure occurs need to be weighed again to determine its moisture content. Result 1. Draw a sketch to depict the sample failure. 2. Determine the angle between failure surface and horizontal surface. 3. From table, Plot these graphs: a) Deviator stress Δσ (N/mm 2 ) versus axial strain ε (mm/mm) From this graph, determine the maksimum value of Δσ Δσ mak = 10

11 Deviator Stress Δσ (N/mm²) Shear Stress τ (N/mm²) Strain, ε (mm/mm) Deviator stress Δσ (N/mm²) versus axial strain ε (mm/mm) Normal Stress σn (N/mm²) Mohr circle and failure envelope graph b) Mohr Cirlce and failure envelope plot. From this graph, determine the soil characteristics below, Ф = C u = 11

12 GEOTECHNICAL ENGINEERING SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G2 : UNCONFINED COMPRESSIVE STRENGTH Group No. Sample No. of Testing sampel date πd²/4 Diam.( mm ) 38 Area Ao (mm²) Ht., Lo( mm ) 76 Vol. mm³ Wt. Wet unit. Wt. Water content, w % Dry unit wt. LRC ( kn/div ) Deformation Load Sample Unit Area Corrected Total load Sample dial dial deformation Strain CF area, on sample stress reading L ε kpa L/Lo 1-ε (Ao /col 5) (col. 2*LRC) Tested by Checked by 12

13 GEOTECHNICAL ENGINEERING SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G2 : UNCONFINED COMPRESSIVE STRENGTH Group No. Sample No. of Testing sampel date πd²/4 Diam.( mm ) 38 Area Ao (mm²) Ht., Lo( mm ) 76 Vol. mm³ Wt. Wet unit. Wt. Water content, w % Dry unit wt. LRC ( kn/div ) Deformation Load Sample Unit Area Corrected Total load Sample dial dial deformation Strain CF area, on sample stress reading L ε kpa L/Lo 1-ε (Ao /col 5) (col. 2*LRC) Tested by Checked by 13

14 GEOTECHNICAL ENGINEERING SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G2 : UNCONFINED COMPRESSIVE STRENGTH Group No. Sample No. of Testing sampel date πd²/4 Diam.( mm ) 38 Area Ao (mm²) Ht., Lo( mm ) 76 Vol. mm³ Wt. Wet unit. Wt. Water content, w % Dry unit wt. LRC ( kn/div ) Deformation Load Sample Unit Area Corrected Total load Sample dial dial deformation Strain CF area, on sample stress reading L ε kpa L/Lo 1-ε (Ao /col 5) (col. 2*LRC) Tested by Checked by 14

15 G3 - CONSOLIDATION TEST (OEDOMETER ) Purpose This test is performed to determine the magnitude and rate of volume decrease that a laterally confined soil specimen undergoes when subjected to different vertical pressures. From the measured data, the consolidation curve (pressure-void ratio relationship) can be plotted. This data is useful in determining the compression index, the recompression index and the preconsolidation pressure (or maximum past pressure) of the sol In addition, the data obtained can also be used to determine the coefficient of consolidation and the coefficient of secondary compression of the soil. Significance I The consolidation properties determined from the consolidation test are used to estimate the magnitude and the rate of both primary and secondary consolidation settlement of a structure or an earthfiil. Estimates of this type are of key importance in the design of engineered structures and the evaluation of their performance. Apparatus Consolidation device (including ring, porous stones, water reservoir, and load plate), Dial gauge ( inch = 1.0 on dial), Sample trimming device, glass plate, Metal straight edge, Clock, Moisture can, Filter paper. Assumption 1. Soil is homogenous and fully saturated. 2. Soil is made of mineral particles that cannot be compacted. 3. Water cannot be compacted 4. Darcy's Law is true for water flow in consolidation process. 5. Changes is volume occur in the applied stress direction, which is one-dimensional changes. 6. Compressive value is constant in applied stress direction 7. Volume changes is same as void ratio changes. Theory Consider a soil sample model is applied with an increase effective stress; Volume changes, ΔV, due to increase in effective stress, ΔV, can be given by changes in thickness, ΔH or changes in void ratio, Δe. So volume strain, ΔV = ΔH = Δe V H 1 + e 0 Therefore, changes In thickness, ΔH = Δe H e 0 15

16 Volume strain depends on the increment in effective stress, and consolidation settlement, S c is given by S c = ΔH = m v Δσ H o with m v = volume compressive coefficient so m v = ΔH m²/kn Δσ H o In one-dimensional theory, Terzaghi concluded that one partial differential equation that connecting access pore water pressure, time and a soil element depth that suddenly being imposed with a uniformly distributed load, is δ u = C v = δ²u δ l δz² With And u = access pore water pressure t = elapse time after load imposed Cv = coefficient of consolidation = k m² year γ w m v γ w = water density (kn /m³) k = coefficient of permeability (hydraulic conductivity) (m/year) m v = coefficient of volume compressibility (m 2 /mn) Terzaghi solution for partial differential equation above described in two dimensionless equations, Terzaghi time factor, T v = C v t d² Where d = height of drainage path, and average degree of consolidation, U y = S t S uit = settlement at time t ultimate settlement Procedure (A) Specimen preparation 1. Porous plates need to be heated using distilled water for a few minutes to prevent water absorption from soil specimen and to saturale it. 16

17 2. Dimesion and mass of oedometer ring to be measured. 3. Soil sample carefully trimmed by cutting the outer side, about 6mm from sampling tube so that it has the same diameter with oedometer ring cell. 4. The prepared specimen is placed above oedometer ring. Both of specimen edges need to be at the same level with the upper and lower side of oedometer ring. 5. A filter paper (smaller than ring diameter) is placed within every porous plate and soil specimen to ensure the pores are not clogged with soil particles. 6. Initial moisture content of soil specimen must be measured from the specimen balance. Three samples from the soil specimen must be taken for moisture content measurement to get the average value. 7. Odeometer is fixed and put top loading apparatus carefully so that soil specimen is undisturbed before tested.. (B) Testing Order 1. Looading cap above porous plate is placed so that axial load can be applied. Porous plate centered above soil specimen. 2. Dial gauge is fix to zero and reading is taken, d z. The d z value is dial gauge reading that similar to zero. 3. Oedometer cell is filled with distilled until full. 4. If soil specimen is not soft enough, apply seating pressure similar to 3 kn/m 2. Either record final gauge reading or record gauge reading in certain times passed like given in (B) (5) additional load (6 kn/m 2 ) is applied and record reading in gone times as shown below. Necessity reading times gauge Log of time method Square root of time method O a 1/4min 1/4min 1/2min 1min 1 min 2 ¼ min 2 min 4 min 4 min 6 ¼ min 8 min 9 min 15 min 12 ¼ min 30 min 16 min 1 hour 25 min 2 hour 64 min 4 hour 144 min 8 hour 225 min 16 hour 625 min 24 hour 900 min 1444 min a before load applied O a 17

18 6. Once the last gauge reading recorded, open the apparatus, dry off excess water from soil specimen surface. Specimen is placed in the oven to determine the final moistu content and soil weight. 18

19 GEOTECHNICAL ENGINEERING SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G3 : CONSOLIDATION TEST ( OEDOMETER ) Group No: : Diameter : Height : Load Kg Kg Passing time, t Time log Log t ( t ) 0 sec sec sec sec sec min min min min min min min min min min min Cumulative correction Total effective settlement Time Gauge ΔH -3 x10 mm Time Gauge ΔH -3 x10 mm 19

20 Table 1 : Calculation sheet - Consolidation test Group no : Soil description: : Sample no: Before test Moisture content Sample + ring weight: Ring + plate weight: Sample weight: Dry sample weight: Initial moisture weight: Initial moisture content, m o Specific Gravity, Gs : Diameter, D: Area, A : Height, H : Volume: Density, p : Dry density, ρ d : Initial void ratio, e o = G -1: ρ d Initial saturation, S o = m o G : e o Void ratio changes factor, F = 1 + e 0 : H After test Ring + plate weight: Total Settlement: Dry sample + ring + plate weight: Volume difference: Ring + plate weight : Final volume: Wet sample weight: Final Density: Dry sample weight: Final Dry Density: Moisture weight: Final void ratio, e f : Final moisture content, m f : Final saturation, S f = m f G : e f 20

21 G4 - TRIAXIAL TEST Objective Introduction To determine the shear strength of cohesionless soil sample. Triaxial test had been used widely to determine shear strength of soil and it is suitable for most type of soil. The advantages of using this method are the drainage condition can be control, which enables saturated soil with low permeability to be consolidated if needed. More over, measurement of pore water pressure also can be done. Mostly soil sample in cylinder form with length/diameter ratio of 2 is used in this test. The sample is attached in thin rubber membrane and then placed in plastic cylinder that usually fills with water or glycerin. Fluid medium that been used in this test is water. Unconfined compression will be applied to the soil sample trough fluid compressive in the chamber. Axial stress apply trough vertical loading vane to cause shear failure to the sample. Axial stress applied by loading vane equable to the axis changes that been given and measured using indicator or load cell at the vane. Further more, extension to determine water drainage flow in or flow out trough the sample or to measure pore water pressure such as test condition also given. There are 3 general type of triaxial test that always been done. Consolidated - drained test, CD Consolidated - undrained test, CU Unconsolidated - undrained test, UU Theory In this test, only unconsolidated-undrained test will be done to the soil sample. For unconsolidated-undrained type oftriaxial test, drainage from sample is not allowed while confined pressure, σ 3 is applied. The sample is sheared until it is failed by applying deviation stress, σ d without any drainage. Because drainage is not allowed, this test can be done quickly. Pore water pressure will increase U a when cell pressure, σ 3 is applied. The next increment of pore water pressure with amount of (U d ) happened because of deviation stress. Summation of pore water pressure, u, for sample at any imposition level of deviation stress can be given as; U = U f = U a + (U d ) f This test usually is carried out on clay soil sample and it depends on strength concept which is very important for saturated cohesive soil. Generally, additional axial stress incurred during failure, (Δσ d ) is practically equal without involving confined pressure stress. Therefore, resultant stress of Mohr circle sample failure shaped in horizontal line and known as null friction angle state, Ф = 0 and τ f = C u where C u is undrained shear strength of soil that equal to the radius of the Mohr circle. Then, 21

22 C u = ((Δσ d ) f / 2 A part from that, resultant of both major principle stress and minor principal stress for triaxial test, unconsolidated - undrained test, UU is be given as; Total of major principle stress = σ 3 + (U d ) f = σ 1 Total of minor principal stress = σ 3 Apparatus and Equipment Apparatus and equipment arrangement for conducting the triaxial test are such as which indicated in the laboratory.sample preparation 1. Undisturbed soil carefully extruded from Shelby Tube not to cause any disturb to the soil sample. 2. Extruded sample then prepared in cylindrical shape with 38mm of diameter and 76mm length. 3. Some soil sample taken from Shelby Tube to determine moisture content of the soil. Procedure 1. Determine the height, weight, and moisture content of the sample. 2. Put cylindrical soil sample inside thin rubber membrane. 3. Place the sample inside triaxial testing cell and fill cell with water from deairing system until full. 4. Arrange triaxial test correctly. 5. Start the test using 200kPa of cell pressure. 6. Constant axial load also applied to sample at rate 1mm/min. 7. Reading at failure gauge is recorded for every 25 readings on loading gauge until failure gauge reading becomes regular or reduced or reach maximum value of 16mm (whichever comes first) 8. Repeat test using cell pressure at 400kPa and 600kPa for the next sample. Result Plot graph for deviator stress versus strain for the entire test sample. Draw Mohr Circle and determine value of undrained shear strength C u and angle of friction Ф. 22

23 Consolidated-Drainage (CD) Test Stage 1 Cell pressure, σ3 is applied and water drainage is allowed. In this condition, pore water pressure (U = Uα) is equal to zero. Stage 2 Deviator stress Δσ d is applied slowly and drainage of water is allowed. Pore water pressure that form from deviator stress Δσ d is equal to zero. So, at the failure condition, Δσ d = (Δσ d ) pore water pressure is U f = U α + U d = O. Consolidated-Undrained Test (CU) Stage 1 Cell pressure, σ 3 is applied and water drainage is allowed. In this condition, pore water pressure (U = U a) is equal to zero.. Stage 2 Deviator stress is applied Δσ d but drainage is not allowed. Because of that pore water pressure from the applied stress is not equal to zero. So, at failure Δσ d = (Δσ ) f, meanwhile pore water pressure is U = U f = U a + ( U d ) f In this experiment three soil samples is tested using Unconsolidated Undrained Triaxial test with cell pressure at 200kPa, 400kPa and 600kPa. Three graphs of deviator stress versus strain are produced based on collected data. The maximum deviator stress from the entire graph added with cell pressure in order to determine major principal stress σ 1. Then, Mohr Circle is drawn using the determined major principal stress σ 1 and from the Mohr Circle minor principle stress σ 3 can be determine. 23

24 GEOTECHNICAL ENGINEERING SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G4 : TRIAXIAL TEST Group No. Sample No. of Testing sampel date πd²/4 Diam.( mm ) 38 Area Ao (mm²) Ht., Lo( mm ) 76 Vol. mm³ Wt. Wet unit. Wt. Water content, w % Dry unit wt. LRC ( kn/div ) Deformation Load Sample Unit Area Corrected Total load Sample dial dial deformation Strain CF area, on sample stress reading L ε kpa L/Lo 1-ε (Ao /col 5) (col. 2*LRC) Cell pressure 200 KPA Tested by Checked by 24

25 GEOTECHNICAL ENGINEERING SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G4 : TRIAXIAL TEST Group No. Sample No. of Testing sampel date πd²/4 Diam.( mm ) 38 Area Ao (mm²) Ht., Lo( mm ) 76 Vol. mm³ Wt. Wet unit. Wt. Water content, w % Dry unit wt. LRC ( kn/div ) Deformation Load Sample Unit Area Corrected Total load Sample dial dial deformation Strain CF area, on sample stress reading L ε kpa L/Lo 1-ε (Ao /col 5) (col. 2*LRC) Cell pressure 400 KPA Tested by Checked by 25

26 GEOTECHNICAL ENGINEERING SCHOOL OF CIVIL ENGINEERING ENGINEERING CAMPUS UNIVERSITI SAINS MALAYSIA G4 : TRIAXIAL TEST Group No. Sample No. of Testing sampel date πd²/4 Diam.( mm ) 38 Area Ao (mm²) Ht., Lo( mm ) 76 Vol. mm³ Wt. Wet unit. Wt. Water content, w % Dry unit wt. LRC ( kn/div ) Deformation Load Sample Unit Area Corrected Total load Sample dial dial deformation Strain CF area, on sample stress reading L ε kpa L/Lo 1-ε (Ao /col 5) (col. 2*LRC) Cell pressure 600 KPA Tested by Checked by 26

27 Determination of maximum vertical stress Sample Confining stress, σ3 Maximum stress difference, σ (kpa ) Maximum vertical stress, σ1 ( kpa ) From the plotted Mohr circles, Cohesion, c = Internal friction angle, Ф = 27