Geology, Society, and the Environment-Geol 322 I. A sieve analysis of a soil yie

Question

Geology, Society, and the Environment-Geol 322 I. A sieve analysis of a soil yields the following results: 7 Some Basic Soil Properties 508 254 12.7 6.35 2.54 1.27 635 423 254 127 0635 0254 002 0199 198 /95 | 84 | 68 | 62 | 59 |53 | 44 | 30 23 15 The first row gives the screen size in millimeters, second row in inches (or #, where # refers to sieve openings per inch), and the third row gives the cumulative percent by weight passing the screen, by weight. (For example: 98% of the sample passed through the 1" seive). a. Plot these on the accompanying particle size graph (one inch 25.4 mm). (The unlabeled red crosses on the graph show the millimeters corresponding to U.S. sieve sizes given above). b. Find percent clay, silt, and sand for the soil. They should add to 100%; do not add cobbles or gravel. Click here to enter text. cles , s. c. Use the accompanying triangular graph to classity the soil according to the USDA agronomy system. Click. here to enter test, claglon~ c. Determine the soil's uniformity coefficient (Co) and curvature coefficient (C). Click here to enter text. d. Is this soil well sorted, poorly sorted, or neither? (Note: Engineers define "well graded" the same as geologists define "poorly sorted"). Click here to enter text. e. How might the uniformity coefficient relate to soil permeability (ease with which water will flow through the soil)? Explain the reasoning behind your answer. Click here to enter text

Explanation / Answer

(b) Total sand , slit and clay is 64 % from the graph. so

sand = {( 64 - 22) / 64 } * 100 = 65.625 %

slit = { ( 22 - 6) / 64 } * 100 = 25 %

Clay = (6 / 64) * 100 = 9.375

Total = 65.625 + 25 + 9.375 = 100 % .

(c) Uniform Cofficient ( Cu) = D60 / D10 = 1 / 0.015 = 66.67 ( where 60% and 10 % cut the graph ,that particle size is  D60 and D10 )

Curvature Coefficient ( Cc ) =D230 / D60 * D10 = 0.132 / 1 * 0.015 = 1.127

(d) As uniform coefficient is more than 6 and curvature coefficient is less than 3 so soil is well graded means means particle of size wide range. so soil is well sorted.

(e) Lesser the particle size lesser is the permiability. High Uniform coefficient means soil grains are well sorted leaving less vacant spaces . So high uniform coefficient means less permeability.

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