Soil Testing Labs
Soil is a complex and non-homogeneous natural substance formed over long periods of time due to various geological events and other natural processes. Its complexity is demonstrated by its approximate composition which includes minerals (45 %), air (25 %), water (25 %), & organic matter (5 %). There are various types of soil which differ in physical & chemical compositions, like sand, silt, clay, loam, peat etc. Although the primary use of soil in our nature is to support plants or vegetation, but for all construction related activities like buildings, dams, tunnels, etc. soil is an indispensable ingredient and knowledge of its properties determine its suitability for a particular purpose. The various tests on soil can be broadly categorized into two types:
Classification Tests
which provide information about the general soil characteristics as well as the mechanical properties like strength, size-grading, permeability etc. These tests help to classify soil samples into various different types.
Tests To Determine Engineering Properties,
which evaluate the usefulness or suitability of a particular soil specimen for a construction related work.
Besides the above types of tests, other tests are also conducted to determine various other parameters which help in deciphering its internal structures, contamination, and other aspects. These include various chemical tests and corrosion tests.
Spectro Analytical Labs Pvt. Ltd.
has a vast & rich experience when it comes to conducting various tests on soil and also carrying out soil investigation studies.
Soil Investigation Studies
Boring
Boring is done as per IS: 1892, making use of mechanically operated equipments. Boreholes of nominal diameter 150mm minimum will be sunk employing shell and auger equipment or any other duly approved method or technique. The size of the drill holes will be normally NX (73mm), but may be reduced to BX (60mm) depending on soil surface layers or strata conditions.
Drilling in rock and collection of rock core samples are done in accordance with IS: 6962, IS: 4464 and IS: 10208. The observations for Core drilling are undertaken in accordance with IS: 5313.
Boreholes are taken down to a layer at which N value is greater than 50. However, if hard rock is encountered on a continuing basis during the process of boring, drilling is continued for a depth of one meter into hard rock before terminating the boring process.
Standard Penetration Test
Standard penetration tes is an in situ test done to evaluate the engineering properties of sub-surface soil strata. It is a common, simple, and inexpensive test conducted to determine the shear strength parameters and the relative densities of soils. The tests are generally carried out at intervals of 1.5 meters or at every change of strata, whichever is met earlier. The tests are conducted by following IS: 2131. The intervals of penetration are increased to 3m if in between vane shear or cone penetration test is performed.
Cyclic Plate Load Test
Cyclic Plate Load[ test is carried out in the field to assess or evaluate the allowable or maximum bearing capacity of soil for design of foundation structures. The test is done as per IS: 5249.The plate will be located at a depth of 3.0 m in a pit excavated as mentioned in IS: 1888.
The application of the load on the test plate is done gradually taking care to avoid impact, fluctuation, tilting of plate or eccentricity, so as to apply a uniformly distributed static load on the soil. The load is maintained constant throughout for a particular time period till no further settlement occurs or the rate of settlement becomes almost negligible.
The loading is increased in increments of 5 tons per square meter until the total settlement of the plate is 25mm or the soil under the plate fails, whichever occurs earlier. Settlement of the plate is recorded by dial gauges of minimum accuracy of 0.02mm, fixed at diametrically opposite ends, and the tests are done as per IS: 1888.
The entire load is made to remove quickly but gradually and the plate is allowed to rebound; when no further rebound occurs or the rate of rebound becomes negligible the readings of the dial gauges are again noted.
The cycles of loading, unloading are continued till the estimated ultimate load has been reached; the final values of readings of dial gauges being noted each time. The value of the load increment will be such that the ultimate or final load is reached within 5 to 6 increments.
From the data obtained during this test, the elastic rebound of the plate corresponding to each intensity of loading is plotted. Finally, the dynamic properties of soil are furnished along-with detailed calculations and plots.
