Reference no: EM133629105 , Length: 2 pages

COMPACTION OF SOILS AND CONSOLIDATION OF SOIL

• Distinguish between standard and modified proctor test.
• Briefly explain the use of proctor needle in field compaction control.
• What are the different compacting equipments used for compacting the soil in the field? Explain briefly.
• Discuss the effect of compaction on soil properties.
• Calculate the compaction energy corresponding to standard proctor and modified proctor compaction.
• Briefly explain how water content, compactive effort and type of soil affect the compaction.
• With a neat sketch, define the term'line of optimums".
• Draw typical compaction curves (γd v/s moisture content) for i.well-graded gravel with fines,ii.well graded sandy clay,iii.silty clay and iv.high plastic clay.
• * What are the laws governing compaction of i. cohesionless soils like sand and ii. Moderately cohesive soils like sandy clay?.
• Listing the various factors that influence the compaction of soils, show their influence with illustrative sketches of compaction curves.
• Jan/2005.During a compaction test, a soil attains a maximum dry density of 18KN/m3 at water content of 12%. The specific gravity of soil is 2.67. Determine the degree of saturation, percentage air voids at maximum dry density. Also find the theoretical maximum dry density corresponding to zero air void at the optimum moisture content.
• During a compaction test, a soil attains a maximum dry density of 18.6KN/m3 at a water content of 15percent. The specific gravity of soil is 2.70. Determine the degree of saturation and percentage air voids at the maximum dry density. What would be the theoretical maximum dry density corresponding to zero air voids at the optimum water content?.
• Jan/2007. A laboratory compaction test on a soil having g=2.68 gave a maximum dry density of 17.85KN/m3 and the moisture content 17%. Find the degree of saturation, air content and percentage of air voids at the maximum dry density. Also find the theoretical maximum dry density with respect to zero-air voids at O.M.C.
• Jan/2004. Standard Proctor compaction test, conducted on a soil yielded the following results.

• Find the maximum dry density and optimum moisture content by plotting the compaction curve. Also plot 100% and 80% saturation lines.

• July/2005. The following data was obtained from proctor compaction test.

Water content (w%)    5.9    7.60    9.61    11.61    13.81       
Weight of wet sample (KN)    18.20    19.50    20.00    20.00    19.80

Sp.gr of soil=2.70, volume of mould=9.5*10-4m3. Plot the moisture content dry density curve and zero air void line. Determine OMC and maximum dry density of the sample.

• Obtain the value of compactive energy imported to the soil during modified proctor compaction test.
• In an earth embankment is compacted at a water content of 18% to a bulk density of 19.2KN/m3. If the specific gravity of the sand is 2.7, find the void ratio and the degree of saturation of the compacted embankment.
• A moist soil sample compacted into a mould of 1000cm3 capacity and weight 35N, weighs 53.5N with the mould. A representative sample of soil taken from it has an initial weight of 0.187N and even dry weight of 0.169N. determine a. water content, d, wet density, c. dry density, d. void ratio and e. degree of saturation of sample.
• a soil in the borrow pit has a void ratio of 0.90. A fill-in-place volume of 20,000m3 is to be constructed with an in-place dry density of 18.84KN/m3. If the owner of borrows area is to be compensated at Rs 1.5 per cubic meter of excavation, determine the cost of compensation.
• A soil in the borrow pit at a dry density of 17KN/m3 with a moisture content of 10%. The soil is excavated from this pit and compacted in a embankment to a dry density of 18KN/m3 with a moisture content of 15%. Compute the quantity of soil to be excavated from the borrow pit and the amount of water to be added for 100m3 of compacted soil in the embankment.
• The following data have been obtained in a standard laboratory proctor compaction test on glacial till;

Water content in w%    5.02    8.81    11.25    13.05    14.40    19.25       
Weight of container and compacted soil in KN    35.80    37.30    39.32    40.00    40.07    39.07

The specific gravity of the soil particles is 2.77. The container is 9.44cm3 in volume and its weight is 19.78N. Plot the compaction curve and determine the optimum moisture content. Also compute the void ratio and degree of saturation at optimum condition.

• Given standard soil compaction test results as follows;

Trial No    Moisture content in % by dry weight    Wet unit weight of compacted soil in KN/m3       
1    8.3    19.80       
2    10.50    21.30       
3    11.30    21.60       
4    13.40    21.20       
5    13.80    20.80

• For a compacted soil, Gs=2.72, w=18%,and γd=0.9 γw. Determine the dry unit weight of the compacted soil.

• The laboratory test results of standard proctor test are given in the following table;

Volume of mould in m3    Weight of moist soil in mould in KN    Moisture content, w in %       
1/30    3.63    10       
1/30    3.86    12       
1/30    4.02    14       
1/30    3.98    16       
1/30    3.88    18       
1/30    3.73    20

• A proctor compaction test was conducted on a soil sample, and the following observations were made;

Water content in w%    7.7    11.5    14.60    17.50    19.70    21.20       
Mass of wet soil in gm    1739    1919    2081    2033    1986    1948

If the volume of the mould was 950cm3 and the specific gravity of soils grains was 2.65, make necessary calculations and draw ,i. compaction curve and ii. 80% and iii. 100% saturation lines.

CONSOLIDATION OF SOILS

• Distinguish between normally consolidated and under consolidated soils.
• Define preconsolidation pressure. How do you determine the same by Casagrande's graphical method.
• Explain in detail, how to determine the coefficient of consolidation by square root of time fitting method..
• Explain with suitable analogy Terzaghi's one-dimensional consolidation of soils.
• Explain by logarithm of time fitting method to find the coefficient of consolidation of soils.
• Explain the quick sand phenomenon in soils.
• Differentiate between;
• Normally consolidated clays and over consolidated clays. ii. Coefficient of consolidation and degree of consolidation.
• iii. Compression index and recompression index.
• What are ‘Curve fitting' method? Explain any one of them.
• State the assumption made in Terzaghi's theory of one-dimensional consolidation..
• Define the terms'Compression index', ‘coefficient of consolidation;,and'coefficient of compressibility', and indicate their units and their symbols.
• Jan/2005. In a consolidation test the void ratio of soil sample decreases from 1.20 to 1.10 when the pressure is increased from 160 to 320KN/m2. Calculate the co-efficient of consolidation if the co-efficient of permeability is 8X10-7mm/sec.
• July/2005. In a consolidation test voids ration decreases from .7o to 0.65, when the load was changed from 50KN/m2 to 100KN/m2. Compute compression index and coefficient of volume change.
• Jan/2004. Saturated soil of 5m thick lies above an impervious stratum below a pervious stratum. It has compression index 0.25 and k is 3.2*10-10m/sec. Its void ratio at a stress of 147KN/m2 is 1.9, Calculate;
• The change in void ratio due to increase of stress to 190KN/m2. ii. Coefficient of volume compressibility.
• iii. Co-efficient of consolidation. iv. Time required for 50% consolidation.
• July/2004. A saturated soil stratum of 5m thick lies above an impervious stratum. It has a compression index
• of 0.25 and a Coefficient of permeability of 3.2*10-3mm/sec. It has a void ratio of 1.9 at normal stress of 0.15N/mm2. Compute;
• The void ratio due to increase of stress to 0.2N/mm2, ii. Settlement of soil stratum due to the above increase in stress.
• July/2005. In a consolidation test voids ratio decreased from 0.7 to 0.65 hen the load was changed from 50KN/m2 to 100KN/m2. Compute compression index and co-efficient of volume change.
• July/2004. A stratum of clay 8m deep, has WL=45%. The surface of clay is at 10m below the present ground level, w=40% and Gs=2.78 for clay. Between ground surface and clay, the subsoil consists of fine grained sand. The ground water level is 4.5m below ground level. The average submerged unit weight of sand is 10.4KN/m3 and the unit weight of sand above the water table is 17KN/m3. The clay is normally consolidated. The weight of structure coming on top of the sand above the clay increases the overburden pressure on clay by 40KN/m2. Calculate the settlement of the building.
• Jan/2007. 20mm hick undisturbed sample of saturated clay is tested in laboratory with drainage allowed through top and bottom. Sample reaches 50% consolidation in 35minutes. If clay layer from which sample was obtained is 3.0m thick and is free to drain through top and bottom surfaces, calculate the time required for degree of consolidation in the field. What is the time required if the drainage in the field is only through the top?.
• A Soil investigation at a site gave the following information. The top soil upto a depth of 10.6m is fine sand, and below this lies soft clay layer of 7.6m thick. The water table is at 4.6m below the ground surface. The submerged unit weight of sand γb, is
• 10.4KN/m3 and et unit weight above water table is 17.6KN/m3. the water content of the normally consolidated clay W =40% its liquid, n limit, WL=45%, and specific gravity of he solid particles is 2.78. The proposed construction will transmit a net stress of 120KN/m2. Find the average settlement of the clay layer.
• An Odometer test is performed on a 2cm thick clay sample. After 5 minutes, 50% consolidation is reached. After ho long a time would the same degree of consolidation be achieved in the field where the clay layer is 3.7m thick?. Assume the sample and the clay layer has the same drainage boundary conditions (double drainage).
• A normally consolidated clay of thickness 4m is sandwiched between to sand layers with outlets. The stress at the mid-height of the clay layer was 1.9t/m2 before any loading was placed. However, due to placement of a fill on the ground surface the stress at the mid-height of the clay layer increases by 1.1t/m2. The initial void ratio and compression index of clay were 1.2 and 0.3 respectively. Determine the total compression of the clay a long time after placement of the fill and time required for 20% and 80% of ultimate compression f co-efficient of consolidation of clay is 4*10-3cm2/sec.
• July/2007. A one dimensional consolidation test as conducted on a clay sample, with double drainage condition. The dial gauge readings recorded for a pressure increment of 100kpa to 200kpa are shown in the table below. One division of the dial gauge corresponds to 1*10-3mm. The thickness of the clay sample at 100kpa overburden pressure was 16mm. determine the value of coefficient of consolidation of the clay by rectangular hyperbola method.

Elapsed time, minutes    0    0.25    1    2    4    6    9    12    16    25    36    50    60       
Dial readings, divisions    340    360    370    378    386    394    402    410    416    426    434    440    443

• During a consolidation test, a sample of fully saturated clay 3m thick is consolidated under a pressure increment of 200KN/m2. When equilibrium is reached, the sample thickness is reduced to 2.6cm, the pressure is then removed and the sample is allowed to expand and adsorb water . The final thickness is observed as 2.8cm and the final moisture content is determined as 24%. If the specific gravity of the soil solids is 2.7, find the void ratio of the sample before and after consolidation.
• A recently completed fill was 10m thick and its initial average void ratio was 1.0. the fill was loaded on the surface byconstructing an embankment covering a large area of the fill. Some months after the embankment was constructed, measurements of the fill indicated an average void ratio of 0.8. estimate the compression of the fill.
• Soil investigation at a site gave the following information. Fine sand exists to a depth of 10.6m and below this lie a soft clay layer7.6m thick. The water table is at 4.6m below the ground surface. The submerged unit weight of sand γb is 10.4KN/m3, and the wet unit weight above the water table is 17.6KN/m3.The water content of the normally consolidated clay Wn-40%, its liquid limit WL=45%, and the specific gravity of the solid particles is 2.78. the proposed construction will transmit a net stress of 120KN/m2 at the centre of the clay layer. Find the average settlement of the clay layer.
• A strata of normally consolidated clay of thickness 3m is drained on one side only. It has a hydraulic conductivity of k=5*10-8 cm/sec and a coefficient of volume compressibility mv=125*10-2cm2/sec. Determine the ultimate value of the compression of the stratum by assuming a uniformity distributed load of 250KN/m2 and determine the time required for 20percent and 80percent consolidation.NOTE: Submission Date: 05/02/2024 before 11:30am without fail.Staff Incharge: Dr.B.S.Chawhan