Experiments on Soil Mechanics - Assignment Example

Running Header: Experiments on Soil Mechanics Student’s Name: Instructor’s Name: Course Code: Date of Submission: Experiment 1 Casa Grande Introduction The casa grande test is usually used in determining the soil’s liquid limit. This test can be used on various varieties of soil although the dried soil is mostly preferred as illustrated by Head (2006). Equipment Distilled water A set of scales A grooving tool 3 small metal dishes An oven 2 palette knives A “knocking device” Method 1. The soil sample is mixed thoroughly with distilled water by use of the palette knife till it mixes homogeneously; this is to create wet soil. 2. A soil sample of 200g is taken and put into a curved bowl on the knocking equipment. 3. Then the sample in the curved bowl is levelled off where grooving tool is dragged down vertically on the sample’s centre part in order to create a consistent grove on the sample. 4. The bowl is afterwards taken back to the knocking device. 5. The knocking device is afterwards turned manually checking to such a time when the groove that has separated down the dish, has closed up for 10mm in a row. 6. The recording is done for the number of blows it takes for the gap to close. 7. The weighing of the empty container is done while the soil sample is taken out of the curved bowl and put in a container. 8. The soil is then put in the oven for 24hrs to ensure it dries completely and then weighed again. 9. This is repeated for 3times using varying water amounts. Results Test 1 29 knocks empty container – 9.5g container with wet contents- 25.3g without container = 15.8g container with dry contents- 20.4g without container = 10.9g moisture content = mass of moisture/mass of dry soil x 100% mass of moisture= (mass of wet soil +container)- (mass of dry soil +container) mass of moisture = 25.3 – 20.4 = 4.9g moisture content = 4.9/10.9 x100% = 44.94%  Test 2 17 knocks empty container -9.3g container with wet contents – 37.3g without container – 28g container with dry contents - 34.8g without container – 25.5g mass of moisture = 37.3 – 34.8= 2.5g moisture content = 2.5/ 25.5 x 100% = 9.8% Test 3 Empty container – 9.3g Container with wet contents – 37g without container – 27.7g Container with dry contents – 31.2g without container – 21.9 Mass of moisture = 37 – 31.2 = 5.8g Moisture content = 5.8/ 21.9 x100% = 26.48% Risk Assessment There are no significant levels of risk in this experiment. Nevertheless, it is important to be extremely careful when using the oven especially when at high temperatures. This is because it can easily burn. However, this precaution is taken through common sense other than safety equipment. Fair test There is need for this test to be done accurately. This is through ensuring that the facilities are identical. This is towards making sure that there is no contamination of results due to use of unclean equipment used in other experiments. The equipments must be thoroughly cleaned and dried before every practical/experiment is undertaken. Experiment 2 Cone Penetrometer Introduction The cone penetrometer experiment is usually used in determining the soil sample’s liquid limit in either its air dried or natural condition as stated by Rattan (2004). However, the sample should be dried before it is used. Equipments An oven 3 containers for drying samples A cone Penetrometer Distilled water 2 palette knives A set of scales A metal cup for placing the sample in at least 40mm in depth Method 1. The water is thoroughly mixed with the dry soil using palette knives in order to get wet soil. 2. A soil sample is then taken and placed into the cup to go into the dish 40mm deep. The container requires filling and then smoothing off at the top. 3. The sample is then placed beneath the cone with cone resting on but without surface penetration. 4. The cone is then released and allowed to move down to the bottom of the sample through gravity. 5. The penetration depth is the measured off the dial. 6. The drying container is weighed and the soil sample added and weighed again. 7. The sample is then placed in the oven for 24hours. 8. The sample is weighed again when dry. 9. This process is repeated for 3 times using different water quantities. Results Test 1 Depth penetrated – 13.5mm Container empty – 9.4g container with wet contents – 29.1g without container – 19.7g container with dry contents – 23.2g without container – 13.8g Moisture content - mass of moisture/mass of dry soil x 100% Mass of moisture–(mass of wet contents + container)–(mass of dry contents + container) Mass of moisture = 29.1 – 23.2 = 5.9g Moisture content= 5.9/13.8 x100% = 42.75% Test 2 Depth penetrated- 25mm Empty container- 6.6g Container with wet contents – 35.3g without container – 28.7g Container with dry contents – 28.1g without container – 21.5g Mass of moisture – 35.3g- 28.1g = 7.2g Moisture content = 7.2/ 21.5x100%= 33.49% Test 3  Depth penetrated- 16.5mm Container empty – 6.3g Container with wet contents – 37.8g without container – 31.5g Container with dry contents – 30.4g without container – 24.1g Mass of moisture – 37.8 – 30.4 = 7.4g Moisture content- 7.4/ 24.1 x100% = 30.71% Fair test The used equipments must be clean and identical to the previous used equipments. This is towards making sure there is no contamination of the results under any under circumstances as well as ensuring there is no biasness in the results. Risk Assessment In performing the cone penetrometer test, there are no significant risks. Nevertheless, care must be taken into consideration when working with a hot oven to avoid incidents of burn. However, this precaution is taken through common sense other than safety equipment. Experiment 3 Worm Test Introduction The worm test is used in the identification of the soil’s plastic limits. It determines the contents of moisture at which the soils turn plastic as illustrated by Head (2006). This is through taking natural soil samples and rolling them out until it starts to crumble. Equipments Distilled water An oven for drying the samples 2 palette knives A cloth or paper towels for drying the hands and glass 2 containers for sample drying A flat glass plate Method 1. The water is added to the soil to make it wet. 2. A sample is taken and placed on the glass plate. 3. The soil is rolled into a ball. 4. The ball is rolled using the hand till it forms a long thread. When the cracks start forming on the surface, wipe the glass surface and the hands to remove any moisture. 5. The empty container is weighed and then the soil is then placed in. It is then reweighed after soil is put inside. 6. The sample is then dried for 24hrs in the oven. 7. The sample is then weighed again after drying. 8. This is repeated again for 3times. Results Test 1  Empty container 9.4g Container with wet contents = 15.7g without container = 6.3g Container with dry contents = 14.4g without container = 5g Moisture content = mass of moisture/mass of dry soil x 100% Mass of moisture = 15.7 – 14.4 = 1.3g Moisture content = 1.3/ 5 x100% = 26% Test 2  Empty container = 9.3g Container with wet contents = 18.4g without container = 9.1g Container with dry contents = 16.6 without container = 7.3g Mass of moisture = 18.4- 16.6 = 1.8g Moisture content = 1.8/7.3 x100% = 24.5g Fair test In ensuring a fair test, the hands must be dry when starting both tests. This is towards ensuring there is no materials’ contamination. Risk Assessment This is no significant risk in this experiment. However, care must be given first priority while dealing with hot oven to avoid burns. However, this precaution is taken through common sense other than safety equipment. Experiment 4 Sieve test Introduction In identifying the particle sizes of the soil type samples, a sieve is used. The sample is usually placed on a sieves stack with each one having a size mesh of different sizes for sorting out the soil into sizes as stated by Rattan (2004). The soil samples are shaken on an Endecott sieve shaker. Equipments A scoop An Endecott shaker A variety of different sieves Scales Method 1. A suitable sample of oven dried soil is selected 2. A sample of soil is weighed to determine the amount left in every pan 3. Every individual sieve is weighed 4. The sieves are placed in top of each other according to size. The sample is placed in the top sieve 5. The stack of sieves is placed onto the shaker 6. The shaker is turned on for a minimum of 10minutes 7. Each sieve is individually weighed with its contents to determine how much is left in each sieve Results Original weight = 500g Total left in sieve= 500g Analysis From the results, the data corrected is correct, as the soil amounts left in the sieves are equal to total put in. This data can be used on a logarithmic scale in trying to identify the soil type that we have been testing. Fair test In ensuring that there is a fair test, one should make sure that the sieves are clean before using. This is towards ensuring any soil left in the sieves makes the data inaccurate. Risk Assessment The Endecott shaker is usually noisy when being used hence the need to use ear protectors. This is towards ensuring the ears are not damaged in case it is used for a long time which may lead to a permanent ear problem. Experiment 5 Specific Gravity Test Introduction The specific gravity test of soil is used to test the specific gravity of a soil. This test is appropriate for all soil types in exceptional of those with more than 10% stones. Equipments A rotating machine A set of Scales A glass plate for closing the jar 2 x 1 litre glass jars with bungs Method 1. The glass jar and glass plate are weighed, then a sample of 200g is placed into the glass jar and then the glass jar and all the contents are reweighed together. 2. Around 500ml of water is placed into the sample inside the jar. 3. The bung is placed on the glass jar which is then shaken using hand and then placed in the rotating machine. 4. It is shaken and rotated until it mixes completely. 5. It is then taken out of the machine and bung removed carefully. The soil on the bung is removed and put back into the jar. 6. Water is then put into the jar up to the top and weighed together with the glass jar. 7. It is then emptied and washed and then filled with water again up to the top and weighed again with the glass plate on it. 8. A second sample experiment is repeated. Results Gs = specific gravity M1= mass of jar, and glass plate M2= mass of jar, plate and soil M3= mass of jar, plate, soil and water M4= mass of jar, plate, and water Gs= M2-M1/(M4-M1)-(M3-M2) Test 1 M1= 830.7g M2= 1257.1g M3= 2348.1g M4= 2081.7g Gs= (1257.1-830.7)/ (2081.7-830.7) – (2348.1 – 1257.1) Gs= 2.68 Test 2 M1= 839.7g M2=1379.3g M3= 2438.3g M4= 2100.6g GS= 1379.3-839.7/( 2100.6- 838.7) – (2438.3 – 1379.1)  Gs = 2.66 Analysis In case the results are not found to be 0.03 of one another, then the test should be repeated. However, in case the test is within 0.02 of each other, this indicates that they are correct and no mistakes have been made during the experiment. Fair test The mixing of soil should be done at the same time duration in ensuring they are equally mixed. This will also ensure that they are no discrepancy in the results Risk Assessment The placement of the soil in glass in the rotating machine is risky. This is because if it can be done incorrectly it can lead to flying off and breaking of the glass jar and subsequently total damage and disruption of the experiment. This can be avoided by ensuring enough time is taken as well as ensuring the jar is fitted tightly before switching the machine on. Experiment 6 Falling head test Introduction This test is used in the determination of permeability coefficient. However, this test is used mainly for those soils that are specifically fined grained such as clays and silts as stated by Rattan (2004). It is used on those soils as they are too fine to be tested using a constant head. Equipments Beakers A soil sample Falling head test apparatus Method 1. The sample is placed in the tube and then filled with de-aired water and allow seepage. 2. The height of the stand pipe is recorded at timed intervals. 3. This is repeated using varying heights of stand pipe. Results Small pipe diameter = 6mm (a)  Cylinder diameter = 62mm (A) Height of sand = 200mm Sample1 Sample 2 Sample 3 Sample 4 1st (mm) 262 221 232 298 Last (mm) 200 200 200 200 Time (s) 11.69 7.68 9.31 18.03 K = a x L Loge ( H1/H2) /A x (t) a= pi x 3mm^2 = 113.1 mm^2 A= pi x 31mm^2 = 12076.3 mm^2 L = 200mm t= time (s) H1= 200 Risk Assessment In this experiment, there is no any risk that is involved. This is because it only involves turning on and off of the taps. Experiment 7 Constant Head Parameter Introduction This test is used for finding out the permeability coefficients of materials that have coarse grains. This is through the use of constant head parameter. Equipments Soil sample Stop clock Ruler Beakers Constant head parameters Results  Pipe 1 (highest) – 180mm Height of sample -200mm Pipe 2 (middle) – 110mm Pipe 3 (lowest) – 45mm Internal diameter = 75mm  Pipe before After 1 797 797 2 652 681 3 624 624 Risk Assessment The process involves turning off and on of the taps hence no risk is involved. Experiment 8 Proctor Test Introduction This test is used in determining the mass of dry soil per cubic metre as argued by Smith & Mullins (2000). This is through dropping a 2.5kg rammer onto a sample from a height of 30cm. Equipments An oven A set of scales A palette knife A 2.5kg metal rammer A metal cylinder mould Drying containers Method 1. An empty cylinder is weighed. 2. The soil samples are mixed with water. 3. The cylinder is filled with soil sample and tamped 24times in order to compress. 4. The sample and cone are then weighed. 5. The empty container is weighed. 6. Sample is put into the container and then weighed. 7. The sample in the container is put into the oven for 24hrs. 8. The sample is then weighed when dry. 9. This is repeated with varying water amounts. Results Sample No. 1 2 3 Sample 1 Sample 2 Sample 3 Cone empty(m1)(g) 4447 4447 4447 Cone full(m2)(g) 6037 6280 6241 Container empty(g) 9.6 9.5 10.5 Container and wet sample (g) 24.2 47.2 49.8 Container and dry sample(g) 22.3 40.3 40.6 Moisture content (w) 14.96% 22.40% 30.56% Bulk density(p)= (m2-m1)/1000 1.59 1.83 1.79 Dry density(Pd)=100p/(100+w) 1.38 1.50 1.37 Risk Assessment This is significant amounts of risk when undertaking this experiment. This is due to dropping hammer which if not carefully dropped; it can fall onto the feet which can be damaging. Therefore, there is need to be careful through wearing toe-tectors or protective footwear when dropping the hammer. Experiment 9 Undrained Triaxial Introduction This tests the shear strength of a material and they way it reacts under compressive pressure as argued by Smith & Mullins (2000). The test is carried out on 3 identical samples to test soil consistency. Equipment 4.5KN proving ring O rings Sample tubes Rubber membrane Stop clock Triaxial pressure tester Spade Method 1. 3 identical samples are taken out from the ground. 2. The first sample is put in a protective rubber membrane. 3. In ensuring the membrane does not come out, an O ring is attached. 4. A sample is put into a compression machine cautiously in order to avoid knocking the sample being tested. 5. The water is put into the cylinder around the sample. 6. A force of 200Kpa is then applied. 7. The axial and displacement load is recorded after every 30minutes. 8. This process is repeated until failure. 9. The sample is removed carefully after failure in order to observe the type of failure. 10. This is repeated with 2 other samples at 600Kpa and 400Kpa. Risk Assessment The only probable risk in this test is when removing soil samples from the ground. This is due to digging process hence the need to take great care when digging. Experiment 10 Shear Box Introduction This experiment is done to test the shear strength of soil. This is done by placing soil sample on the shear machine and then forcing it apart by the using that machine as illustrated by Head (2006). This usually pulls the soil sample apart horizontally until it drops. Equipment Soil sample Stop clock 3KN proving ring Shear box Shearing machine Method 1. A sample is placed inside the shear box. 2. The shearing plated are then put at 90degrees to where it will be pulled. 3. The metal pins are then put in to lock the box in order to make it easier to place into the shearing machine. 4. The metal pins are then removed and box is secured into the machine before the desired weight loads are attached. 5. The machine is then turned on and readings are taken of the load being used after every 30seconds. 6. This is repeated for all the weights. Results Time(s) 30Kg 40Kg 50Kg 30 20 48 90 60 29 100 139 90 58 143 189 120 89 178 219 150 120 201 245 180 152 212 256 210 170 212 259 240 182 204 249 270 183 198 248 300 179 185 250 330 164 176 360 150 Risk Assessment It is important to take great caution when loading the machine with weights because incorrect loading can damage one’s back. To avoid this, one should ensure that the back is straight while lifting. This will ensure they are no injuries that occur. References Head, K2006, Manual of Soil Laboratory Testing: Soil classification and compaction tests, Whittles, Michigan. Rattan, L 2004, Principles of Soil Physics, CRC Press, New York. Smith & Mullins 2000, Soil Analysis: Physical Methods, Revised and Expanded, CRC Press, New York. Read More