Surveying for Civil Engineers

Soil test

Soil testing

Soil testing is often performed by commercial labs that offer a variety of tests targeting groups of compounds and minerals. There may be some advantage to using a local lab that is familiar with the chemistry of the soil in the area where the sample was taken. This enables technicians to recommend the tests most likely to reveal useful information.

Laboratory tests often check for plant nutrients in 3 categories:

• Major nutrients: nitrogen (N), phosphorus (P), and potassium (K)


• Secondary nutrients: secondary nutrients - sulphur, calcium, magnesium


• Minor nutrients: iron, manganese, copper, zinc, boron, molybdenum, aluminum.

Do-it-yourself kits usually only test for the three "major nutrients" and for soil acidity or pH level. Do-it-yourself kits are often sold at farming cooperatives, university labs, private labs, and some hardware and gardening stores. Electrical meters that measure pH, water content, and sometimes nutrient content of the soil are also available at many hardware stores. Laboratory tests are more accurate than tests with do-it-yourself kits and electrical meters. Here is an example soil sample report from one laboratory.

Soil testing is used to facilitate fertilizer composition and dosage selection for land employed in both agricultural and horticultural industries.

Prepaid mail-in kits for soil and ground water testing are available to facilitate the packaging and delivery of samples to a laboratory. Similarly, in 2004, laboratories began providing fertilizer recommendations along with the soil composition report.

Lab tests are more accurate, though both types are useful. In addition, lab tests frequently include professional interpretation of results and recommendations. Always refer to all proviso statements included in a lab report - these may outline any anomalies, exceptions and shortcomings in the sampling and/or analytical process/results.

Lead is a particularly dangerous soil component. The following table from UMinn categorizes typical soil concentration levels and their associated health risks.

Floating raft system

Floating raft is type of land-based foundation that protects against settlement and the liquefaction of soft soil due to seismic activity. It was a necessary innovation in the development of tall buildings in the wet soil of Chicago in the 19th century, where it was developed by John Wellborn Root who came up with the idea of interlacing the concrete slab with steel beams.

For a floating raft foundation, or floating foundation, the foundation has a volume such that were that volume filled with soil, it would be equal in weight to the total weight of the structure. When the soil is so soft that even friction piles will not support the building load, the final option is the use of a floating foundation, making the building like a boat that obeys Archimedes’ principle—it is buoyed up by the weight of the earth displaced in creating the foundation.

Slip forming construction

Slip forming, continuous poured, continuously formed, or slipform construction is a construction method in which concrete is poured into a continuously moving form.^[1] Slip forming is used for tall structures (such as bridges, towers, buildings, and dams), as well as horizontal structures, such as roadways. Slipforming enables continuous, non-interrupted, cast-in-place "flawless" (i.e. no joints) concrete structures which have superior performance characteristics to piecewise construction using discrete form elements. Slip forming relies on the quick-setting properties of concrete, and requires a balance between quick-setting capacity and workability. Concrete needs to be workable enough to be placed into the form and packed, yet quick-setting enough to emerge from the form with strength. This strength is needed because the freshly set concrete must not only permit the form to "slip" upwards but also support the freshly poured concrete above it.

In vertical slip forming the concrete form may be surrounded by a platform on which workers stand, placing steel reinforcing rods into the concrete and ensuring a smooth pour.^[2] Together, the concrete form and working platform are raised by means of hydraulic jacks.^[3] Generally, the slipform rises at a rate which permits the concrete to harden by the time it emerges from the bottom of the form.^[1]

In horizontal slip forming for pavement and traffic separation walls concrete is laid down, vibrated, worked, and settled in place while the form itself slowly moves ahead. This method was initially devised and utilized in Interstate Highway construction initiated by the Eisenhower administration during the 1950s.

K.SUDHAKAR REDDY

 

NAME        :  K.SUDHAKAR REDDY

REGD NO  :  08QT1A0117


BATCH      :  2008-12


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E-Mail        :  iambadboy124@gmail.com

S.KALADHAR 2008-12

NAME            :  S.KALADHAR


REGD NO      :  08QTIA0101


BATCH          :  2008-12


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E-Mail           :  kaladharsandra@gmail.com