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STUDIES ON CHEMICAL AND GEOTECHNICAL PROPERTIES OF MARINE SAND

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STUDIES ON CHEMICAL AND GEOTECHNICAL PROPERTIES OF MARINE SAND Powered By Docstoc
					  International Journal of Advanced Research in OF ADVANCED (IJARET), ISSN 0976 –
  INTERNATIONAL JOURNALEngineering and TechnologyRESEARCH IN
  6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME
             ENGINEERING AND TECHNOLOGY (IJARET)

ISSN 0976 - 6480 (Print)
ISSN 0976 - 6499 (Online)
                                                                         IJARET
Volume 4, Issue 2 March – April 2013, pp. 75-80
© IAEME: www.iaeme.com/ijaret.asp                                       ©IAEME
Journal Impact Factor (2013): 5.8376 (Calculated by GISI)
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    STUDIES ON CHEMICAL AND GEOTECHNICAL PROPERTIES OF
                       MARINE SAND

        Sivaramulu Naidu .D1 *, Madan Mohan Reddy .K2 and Vijaya Sekhar Reddy .M2
    1
        Senior Research Scholar, Department of Civil Engineering, SVUCE, Tirupati, AP, India.
         2
           Assistant Professor, Department of Civil Engineering, SKIT, Srikalahasti, AP, India.



  ABSTRACT

          Present study deals with the Chemical and Geotechnical properties of Marine Sand
  collected from Mypadu Beach, Nellore District, AP, India. Samples selected from two trial-
  pits one at a depth of 0.5-1.0 m (Pit-1) and second at a depth of 1.2-2.0 m (Pit-2) and
  conducted laboratory tests on Chemical and Geotechnical Properties. Samples are said to be
  Alkaline soils and Non-Cohesive because it’s having greater than 8.5 pH and grain sizes
  more than 98% range in 0.075- 1.18 mm respectively. The detailed test results and
  observations are discussed sequentially in the paper.

  Key words: Marine Sand, Chemical Properties, Geotechnical Properties, Maximum, Dry
  Density (MDD), Optimum Moisture Content (OMC), Safe Bearing Capacity (SBC).

  1.0 INTRODUCTION

           A coastal plain corresponding to 0-150 meters covers almost entire coastal Andhra
  with some of the best agricultural land of the state. This area falls between two major river
  deltas, Krishna and Godavari and is largely composed of riverine and coastal alluvial soils
  and in some places red loams. Occupying 3% of the total area of the state the coastal soils are
  very deep (1.8-5mts) with coarse textured sandy subsoil. They are located all along the
  eastern coast, 3-12 km from the sea. Rapidly permeable soils due to very low day content and
  high amounts of sand. Neutral in reaction (pH 6.5- 7.5) with subsoil salinity due to high water
  table. Saline and alkaline soils belong to one group of problem, soil the extent of which is not
  precisely known as no systematic surveys were carried out to asses and map them. These
  soils are estimated to occupy about 1.0 per cent of the total area. The area under salt-affected
  soils in the coastal region is estimated to be 0.176 m ha [1].

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International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME

        The marine sediments present in the Kerala coast between 20 and 80m water depth
carry an appreciable amount of silica sand. Systematic mapping of the seabed and
exploration in selected areas have indicated the presence of huge reserves of construction-
grade sand in different sectors. Sandy sediments in the deeper, western part India are
relatively finer and fall in the fine to medium sand category. The carbonate content is 10-
25% but in certain areas the sand bodies carry 10-15% clay and silt. In certain other
sectors clay contents exceed 25%. The sand also carries economic heavy minerals like
ilmenite, sillimanite, garnet, rutile, Zircon and monazite in small proportions [2].
        The five sites chosen were submitted from moderate to high energy level of
deposition and showed depositional clean graded bedding which is diagnosite of the
presence of storm surges, reflected through storm layers. Five areas and their sedimentary
facies of the actual marine environment were chosen to apply the methodology used on
the transitional coastal sediments[3].
        The pH varied from slightly acidic (5.83) to moderately alkaline (8.47) in the soils
of Sivagiri micro-watershed in Chittoor district of Andhra Pradesh. The variation in soil
pH was related to parent material, rainfall and topography. Further, the KCl-pH values
were lower than the water pH values, indicating the existence of net negative charge on
colloidal particles [4].
        The electrical conductivity of the soils of Garakahalli watershed ranged from 0.02
to 0.20 dSm-1 indicating non-saline nature of the soil. However, these soils did not show
any relationship with depth. This may be due to the undulating nature of the terrain
coupled with free drainage conditions, which favored the removal of releasing bases by
the percolating and drainage water [5]. The Inceptisols and Entisols of Shahibi basin in
Haryana and Delhi were non-saline with electrolyte concentration ranging from 0.18 to
0.95 dSm-1 [6].

2.0 MATERIALS USED IN THE STUDY

        The soil samples were collected 2kms from the sea waterfront on the coast near
Mypadu Beach, Nellore District, AP, India. Two trial-pits one at a depth of 0.5-1.0 m
(Pit-1) and second at a depth of 1.2-2.0 m (Pit-2) and samples were collected in wet
condition from both trial pits (Pit-1 and Pit-2). Tests on soil samples were determined by
standard methods and conducted on Chemical Properties, Geotechnical Properties and
Safe Bearing Capacity. It is mentioned here that three samples were taken at random and
the average values of various properties are taken as the test values.

3.0 RESULTS AND DISCUSSIONS

3.1 Chemical Properties

       Chemical tests were determined by the methodologies [7] suggested by Jackson
(1973) for both Pit-1 and Pit-2 samples and observed the results of Chemical Properties of
marine soil samples are tabulated in Table 1.




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International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME




                    Table 1. Chemical Properties of Marine Soils Samples


                                                                Electrical            Total
                                                               Conductivity        Dissolved
                 Alkalinity     Hardness
  Chemical                                  Chlorides            (µs/cm)          Solids (ppm)
                  (mg/l as      (mg/l as                pH
  Properties                                 (mg/l)
                  CaCo3)         CaCo3)
                                                                  Wet      Dry    Wet     Dry


     Pit -1         670          1387         612       8.62      815      710    2405    2100


     Pit -2         612          1220         574       8.58      702      650    1890    1760


Soils with a pH greater than 8.5 are considered alkaline [1]. Samples collected from the
source were having pH > 8.5 and these soils considered as alkaline soils.

3.2 Geotechnical Properties

        Tests on soil samples were determined by standard methods and observed results are
tabulated in Table 2.
        It is observed that the liquid limit, Plastic Limit, Plasticity Index and Free Swell Index
were zero because of both Pit-1 and Pit-2 samples were cohesion less sand particles.



                   Table 2. Geotechnical Properties of Marine Soil Samples


                                  Natural    Angle of
                      In-Situ     Moistur    Internal                   Bulking           Silt +
  Geotechnical                                           Specific                 Sand
                     Density        e        Friction                   of Sand           Clay
   Properties                                            Gravity                  (%)
                     (kN/m3)      Content      (φ in                      (%)              (%)
                                   (%)       degrees)


       Pit-1         10.867        25.99      29`29”       2.38           12      98.13   1.86


       Pit-2          12.72        27.14       31`9”       2.35           6       99.97   0.23




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International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
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Grain size distribution

        For determination of grain size distribution of marine samples, sieve analysis test was
performed. From the test data, the particle size distribution curve was plotted from which it
was found that the soil consists of more than 98% of particles range in 0.075mm-1.18mm for
both Pit-1 and Pit-2 samples. Therefore the soil samples said to be sand particles. The grain
size distribution curve is depicted in Figure 1.




Compaction test

        The standard proctor compaction test was carried out with remoulded soil sample with
varying moisture content. In each test, the standard Proctor mould (size: 100 mm diameter x
127 mm height) was filled with soil-water water mixture in three equal layers, each layer
being compacted by 25 blows of a 25 N rammer with a height free fall of 300 mm. From the
test results observed Maximum Dry Density (MDD) versus Optimum Moisture Content
(OMC) is depicted in Figure 2. The value of MDD and OMC (depicted in Figure 2) for Pit-1
and Pit-2 was observed 16.68 kN/m3, 16.29 kN/m3 and 15.48%, 15.62 % respectively.

Safe Bearing Capacity

        It is observed from the results Ultimate Bearing Capacity (UBC) and Safe Allowable
Bearing Capacity (SBC) for Pit-1 were found to be 190 kN/m2 and 63 kN/m2 respectively
after considering factor of safety 3.0 and the settlement of 3.80 cm.

        For Pit-2, UBC and SBC were found to be 200 kN/m2 and 67 kN/m2 respectively after
considering factor of safety 3.0 and the settlement of 3.865 cm. However the SBC of
cohesion less, loose, dry and fine sand may be limited to 100 kN/m2 and allowable settlement
of 5.0 cm in accordance with the IS: 6403-1981 [8].


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International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME




4.0 CONCLUSIONS

1. The present studies explain the knowledge about the marine sand in connection with its
   Chemical Properties, Geotechnical Properties and soil Safe Bearing Capacity.
2. The Soil samples are alkaline because of both Pit-1 and Pit-2 having greater pH, than the
   allowable value of 8.5.
3. Grain size distribution of Marine Sand samples shows that the sediments consist of more
   than 98% of sand content when sieved through 0.075 - 4.75 mm size sieves.
4. It is observed that the liquid limit, plastic limit, plasticity index and Free Swell Index
   were zero because of both Pit-1 and Pit-2 were fine sandy particles of the Marine soil.
5. The value of Cohesion were found to be zero and hence only Direct Shear test was
   conducted for finding results of the MDD and OMC in present in soil samples. The test
   results of MDD and OMC for Pit-1 and Pit-2 is 16.68 kN/m3 and 16.29 kN/m3 and
   15.48% and 15.62% respectively.
6. From the results the UBC and SBC of Pit-1 and Pit-2 were found to be 190 kN/m2, 200
   kN/m2 and 63 kN/m2, 67 kN/m2 respectively, after considering factor of safety 3.0.
7. The settlement of foundation is observed for Pit-1 and Pit-2 were 3.80 cm and 3.865
   respectively. These values are also well within the allowable settlement of 5.0 cm as per
   the code.

REFERENCES

[1] www.inseda.org/...Soil%20Science%20(SSS)/ Soils%20of%20Andhra%20Pradesh -369.
    doc, dated.19/03/2013.
[2] Sukumaran .P.V., et. Al. (2010), “Marine sand resources in the south-west continental
     shelf of India”, Indian Journal of Geo-Marine Scinces, Vol.39, No.4, pp.572-578.
[3] Martine .L.R and Barboza .E.G (2005), “Sand-gravel Marine Deposits and Grain-Size
     properties”, Gravel, Vol. N3, pp.59-70.


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International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME

[4] Thangasamy .A, Naidu .M.V.S, Ramavatharam .N and Raghava Reddy .C (2005),
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[10] K.V. Maheshwari, Dr. A.K. Desai and Dr. C.H. Solanki, “Bearing Capacity of Fiber
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