US3720369A

US3720369A - Soil analysis and device therefor

Info

Publication number: US3720369A
Application number: US00127546A
Authority: US
Inventors: S Alvarado
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-03-24
Filing date: 1971-03-24
Publication date: 1973-03-13
Anticipated expiration: 1990-03-13

Abstract

A method of determining soil classification characteristics according to known grading systems to facilitate construction of highways, airfields and the like. A computer device correlated thereto to eliminate the necessity of complex tables and charts and a knowledgeable user thereof in arriving at soil classification determination.

Description

United States Patent 1191 Alvarado 1 51March 13, 1973 SOIL ANALYSIS AND DEVICE 1 3,108,746 10/1963 Chrisler ..235 7a HEREFOR 3,243,110 3/]966 Kaserm. 3,360,]95 I2 1967 P" h 1 lnvflnto" Samuel Alvarado, ESPalrta 3,436,014 4jl969 Oth hicky ..23s 7s No. 60, Guaynabo, P.R. 00657 1 22 Filed; March 24 1971 l A Primary Examiner-Stephen J. Tomsky Attorney-Low & Matthews [2i] Appl. No.: 127,546

I [57] ABSTRACT [22] :J.S.Cll ..235/78,235 /88 A method of determining so" classification charac [58] teristics according to known g g systems to 1 led of Search ..235/78, 88, I16 f ilit t construction of highways, airfields and the 56 R i d like. A computer device correlated thereto to l 1 e erences eliminate the necessity of complex tables and charts UNITED STATES PATENTS and a knowledgeable user thereof in arriving at soil classification determination. 2,328,881 9/1943 Saunders.... ....235/78 2,934,264 4/1960 Miller ..235/88 9 Claims, 4 Drawing Figures lllnllull Passing No. III",

PATENTEDHARI 3x913 SHEET 2 OF 3 Fig.3

INVENTOR. Samue/ Laboy Alvarado BY a Wm ATTORNEYS PATENTEDHARISIQB 720,369

SHEET 3 BF 3 Passing No.200

B OQ 30 Or More IT G 40 Or Less 42 I I 60 Or More Fig.4

INV ENTOR Samuel Laboy Alvarado ATTOR N EYS 1 SOIL ANALYSIS AND DEVICE THEREFOR BACKGROUND OF THE INVENTION In laying roads and pavements, it is a necessary and important practice to start with a thorough consideration ofthe soil conditions which will comprise the earth foundation and support for the roadway. Based upon these determined conditions, the thickness, density, and weight of the pavement structure to be laid can be designed and engineered with proper regard for the ability of the soil to support the load.

In order to remove the critical determination of soil characteristics with respect to highway or airfield design from mere guesswrk" subject to indeterminate and variable experience factors affecting the conclusions of a highway engineer, some ordered and logical means for calculating soil classification and index must be provided. A widely used classification and index calculation was developed by the US. Bureau of Public Roads in 1928 and has been revised periodically thereafter. This tabulation is known as the American Association of State Highway Officials system of soil classification, or AASHO for short. The AASHO system has been commonly used by highway engineers for determining the performance of soils under highway pavements. The AASHO system is set forth in more detail in a publication of the Asphalt Instittlte entitled: Soils Manual for Design of Asphalt Pavement Structures, 1969 printing.

Notwithstanding the use of the AASHO classificabe readily determined without resort to tedious processes of elimination and a series of auxiliary dials, tables and the like.

Further, the dial computer of the present invention is used in conjunction with performing the method, and while of simple construction, is comprised of a unique relationship of scale indicia and observing apertures v therefor, whereby soil classification may be determined tiohs, it has still'been necessary for the person making soil calculations to have a working knowledge of the terms frequently used in connection with soil analysis since many of the required calculations depend upon the use of tables and charts which only a person familiar with the terminology would thoroughly understand. This has severely limited versatility of the AASI-IO system, since there are relatively few techniclans who arecompletely versed in the terminology.

The present invention overcomes the need for a familiarity of nomenclature used in connection with the AASHO classification system, thereby broadening the usefulness of the system to persons needing classification and index information on various types of soils.

In view of the foregoing, it is an object of this invention to provide a dial computer for easily and effectively determining soil classification and index where no such computer has before been contemplated.

It is a further object of this invention to provide a dial computer which is simple and compact in construction, and easy to operate in that it does not require the use of auxiliary tables or charts which require a special knowledge of the terminology used in soil classification.

It is a further object of this invention to provide a dial computer which is adaptable to the presently used AASHO system ofclassification. Other objects, features and advantages of the invention will be apparent from the following detailed description, andthe accompanying drawings.

SUMMARY OF THE INVENTION Accordingly, Ihave invented and provided a method of determining soilclassification according to AAI-ISO index or others whereby in the field the classification of 5 the soil encountered for highway or other purposes can speedily and without error in order that construction may proceed, and may be used by personnel which lack skilled training in soil classification analysis.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a dial computer in accordance with the present invention and showing the parts thereof in a position for the initial steps in determining a soil classification;

FIG. 2 is a side elevation of the computer illustrated in FIG. 1;

FIG. 3 is a top plan view of the lowermost computer dial with the superposed scale discs removed, and

FIG. 4 is a rear or bottom view of the dial computer.

Referring now to the drawings, and in particular to FIGS. 1 and 3, the numeral 10 generally indicates a soil analysis computer in accordance with the invention. The computer 10 includes a full-circular base disc 12 having diametrically opposed elongated triangular apertures l3, 15 (FIG. 3), and an arcuate slot 49. The computer further includes three rotatably mounted discs superimposed upon the base disc 12 and connected as by pivot means 17. Disc 20 is next adjacent to and substantially the same diameter as base disc 12, and is apertured at 22, 24 and 26. Further, disc 20 is peripherally arcuately notched at 28,29. Surniounted upon disc 20 is a smaller diameter disc 30 having a single aperture 32. Each of the discs contains indicia necessary for calculation of the soil classification, as noted hereinafter.

As best seen in FIG. 3, base disc 12 has an arcuate scale 14 on its face. The scale 14 is marked in graduations from zero to one hundred which are used to indicate the percentage of soil passing through a 200 mesh sieve. A heavy mark 16 is provided between the 35 to 36 percent graduations to divide'soils into two major groups, that is soils with 35 percent or less passing through the 200 mesh. sieve and the silt-clay materials with more tan 35 percent passing the 200 mesh sieve. These two major groups are further divided into additional sub-groups which will be explained later. To identify the material passing the number 200 sieve as either above or below the 35 percent mark, and to greatly facilitate soil analysis with my device, the scale preferably has shading of different colors on either side of the mark 16, for example, green for the percentageless than 35 percent and yellow for the percentage greater than 35 percent. Further development of the color shading in soil analysis will appear hereinafter.

The aforesaid peripheral notch 29 in second disc 20 exposes the percentage scale 14 as seen in FIG. 1. Aperture 22 is located midway between the end walls of notch 29 and is provided with two arrows, one of I 33 (FIG. 3) on the base 12 so as to always expose a portion of the stripe through the window 22.

Apertures

24 and 26 expose further grouping indicia 35 printed on the face of the base member 12.

The second notch 28 in disc exposes soil group indicia 31 on the face of base member 12. The indicia 31 relates to broad AAHSO soil classifications as Al A-2, etc., and may be used as a reference to the general classification of the soil being analyzed. Generally speaking, the higher the group number, the highest being A7, the poorer the soil, and the greater the structural thickness requirement for the pavement to be built Next topmost dial is provided with an outermost arcuate two-color plasticity index or Pl scale 42 on the periphery, and two substantially

semi-circular scales

44 and 46 radially inwardly thereof. The PI scale 42 indicates the plasticity which the tested soil contains. To

calculate the plasticity of the soil the scale is divided at 48 into semi-circular scale portions. One portion is for plotting the soil'plasticity when less than percent of the soil passes through the 200 mesh sieve, while the other scale portion is for plotting the soil plasticity index when greater than 35 percent passes the sieve. Each of these scales has graduations from zero to 95 percent. These portions of scale 42 are employed in conjunction with base member scale 14, and are similarly color-shaded.

The double arrow 48 also divides the inner arcuate scales at their zero points. Scale 44 represents the liquid limit obtained from analysis of the tested soil, while scale 46 represents the percentage of tested soil passing through a mesh sieve. As before, differing color shading may be used to correlate and identify each of the scales, such as red for scale 44 and blue for scale 46.

Dial .30 has a double arrow 52 on either side of window 32. Arrows 52 are used for reading the determined AAHSO soil classification categories such as A3, Al-b, A7-5 etc. found on the respective inner and

outer discs

34 and 20.

OPERATION In determining soil classifications from laboratory data, the percentage of soil passing through a 200 mesh sieve is initially entered on percentage scale 14 using indicator arrow 54 adjacent window 22. The next step is to plot the determined plasticity index (PI) of the soil on scale 42 using the inwardly directed portion of arrow 54. Following the plotting of the Pl, the user enters either the determined liquid limit (LL) of the soil on scale 44, or the percentage of soil passing through a 40 percent sieve is plotted in scale 46. However, only one of these scales can be used in calculating the soil group. In this regard, should the percentage of soil passing a No.200 sieve be greater than 25 percent and the Plasticity Index be at least 35 percent, then the Liquid Limit (LL) scale 44 is used. Otherwise the No.40 sieve scale 46 is used.

As a result, double-ended indicator 52 points to a series of soilclassifications on both

discs

20 and 34. From this, a single soil classification common to both discs may be observed, such as the group A7 on disc 34 and the group A7 on disc 20. Radial lines as at 60 segregate the different soil classification on

discs

34 and 20.

When a soil grouping of A7 is shown it is necessary to read the sub-group using special indicator to obtain sub-grouping.

For clarity, an example of the soil classification obtained using the dial computer of the invention is as follows:

Data Given from soil tests:

1 Passing No.200 mesh sieve: 88 percent 2. Plasticity Index: 86

3. Liquid Limit: 55

Perform the following steps as shown:

1. Enter 88 percent on scale 14 using indicator 54 on disc 20.

2. Plot Plasticity Index at 86 on scale 42 since more than 35 percent of the soil passed through the 200 mesh sieve.

3. Enter 55 on the liquid limit (LL) scale 44 with arrow 56 on disc 34.

4. Read the soil classification using indicator 52 on disc 30 which points to classification groups A-6 and A7 on outer disc 20 and to groups A-25, A-27, A5 and A7 on inner disc 34 as defined by radial lines 60.

5. Since the common classification shown by

discs

20 and 34 is group A7, use the special sub group indicator arrow 70 on disc 34 and read soil classification grouping A7-6 along the arcuate arrow 72 in disc 20 outwardly of

scales

42 and 44. In the special instance of the group A7, it will be seen that the appropriate classification grouping is found along either elongated

arcuate arrow

72 or 74.

As previously indicated, there are two major groups in soil classification using the AASHO system. These groups are divided into granular materials with 35 percent or less passing the 200 sieve and the silt-clay materials with more than 35 percent passing the number 200 sieve. Moreover, five soil fractions are recognized and often used in describing a particular soil. These fractions are divided into boulders, gravel, coarse sand, fine sand and combined silt, and sand.

The two major groups are further divided into additional groups and sub-groups as follows:

Granular materials are divided into group Al where there is a non-plastic or slightly plastic soil binder. However, the group is further divided into sub groups Ala for gravel with or without well graded soil binders and Alb for coarse sand with or without well graded soil binders.

Group A3 consists of materials consisting of sands in coarse material and soil binders, while group A-2 consists of a wide variety of granular materials which are borderline between the materials falling in group A1 and group A3 and the silt-clay materials of A4, A5, A6 and A7. Group A4 consists ofa non-plastic or moderately plastic silty soil and group AS is similar to A4, except that it is usually of diatomaceous or Micaceous character. Group A6 is normally a plastic clay soil having 75 percent or more passing through the 200 mesh sieve, and group A7 is similar to group A6, except that they have high liquid limits.

The plasticity index (PI) of a soil is the lowest water content determined in accordance with the procedures set out in the Soils Manual referred to above. The determination of the soils plasticity is based upon how plastic the soil remains after being subjected to a number of tests outlined in the manual. Likewise, the liquid limit (LL) of a soil is also determined in accordance with the manual and is thus stated as being that point at which the soil passes from a plastic to a liquid state using the procedure set out in the manual.

The invention further includes the use of a color shading to aid in effecting the soil analysis. Thus, in using the color-shading system the first value to be plotted as noted will be the percentage of the material passing through a 200 mesh sieve and this is plotted on scale 14 on base member 12. The portion thereof below 35 percent is colored green while the remainder is shaded yellow.

The second value to be plotted will be on the PI scale 42 whose semicircular divisions are also colored green and yellow. When plotting the plasticity index value, therefore, use the same PI scale portion of the color shading as used in plotting 200 mesh percentage figure on scale 14 Window 22 of disc 20 reveals a portion of colored strip 33 on base 12 and similarly window 32 of disc 30 shows a portion of a similar colored strip 37 on disc 20. After the plotting of the plasticity index, the colors showing through

windows

22 and 32 are compared. If both colors are thesame predetermined strip color, such as blue, the next scale to use is the similarly colored scale at 46, showing material passing through a 40 mesh sieve. If one or both slots are red, for instance, the next value will be entered on scale 44, the liquid limit scale.

Therefore, it can be seen in using the color system the calculations are made much simpler, since it is not necessary to keep in mind arithmetic factors such as whether or not 35 percent of the tested soil passes through a 200 mesh sieve.

While not mentioned in detail heretofore, the computer also indicates the Group Index under the AAI'ISO system. The group Index is not a major group classification, but rather a means of evaluating soils as subgrade materials within their groups. The higher the Index number, the poorer quality of the soil in the determined classification group.

Looking at the rear or back of base member 12, FIG. 4, Group index can be found by plotting the amount of soil passing a number 200 sieve on a scale 80 visible through aperture 49 on the back of disc 20, using arrow indicator 82 printed on the base member 12. This is the same figure entered on scale 14. Having plotted the percentage on scale 80 and knowing the plasticity index and liquid limit of the soil fromthe test results, the numbers on the back of disc appearing through plasticity index (PI) window 84 and liquid limit (LL) window 86 are added to give the group index.

Windows

84 and 86 are of elongate triangular shape to separate clearly the numbers on the back of disc 24 for easier reading. a

In the present example, the Group Index will be seen to be about 19, indicating a very poor soil within the already-determined low-grade soil classification A-7.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope ofthe invention, the form hereinbefore described being merely preferred embodiments thereof.

What is claimed is:

1. A dial computer for determining soil classification comprising:

a plurality of superposed discs mounted for relative rotation, said discs including a topmost disc provided with said classification categories thereon,

a second disc therebeneath of greater diameter then said topmost disc and having a window therethrough outwardly of said topmost disc,

a third disc provided with said soil classification categories thereon disposed beneath and of greater diameter than said second disc, portions of said third disc being viewable through said second disc window,

said third disc having first and second windows therein in circumferentially spaced relation and outwardly of said second disc periphery,

said third disc further having a notched arcuate cutout on the disc periphery, with said cutout disposed adjacent said first window,

a fourth disc disposed beneath said third disc, portions of said fourth disc being viewable through said first and second windows and cutout in said third disc, and,

scales on said discs correlated with said windows and said cutout whereby determined soil classifications are indicated on said topmost and third discs for engineering and construction purposes.

2. The dial computer of claim 1 wherein said scales and said soil classification indicies are based upon the AASHO system.

3. The dial computer of claim 1 further including color keying between scales to facilitate use thereof.

4. The dial computer of claim 1 further including a third window adjacent said second window in said third disc,

said third window being at a different radius from that of said second window, thereby to expose a different portion of said fourth disc.

5. The dial computer of claim 1 further including an arcuate window in said fourth disc through which soil indicia on said third disc is viewable when said computer is inverted.

6. The dial computer of claim 5 further including a pair of radially disposed windows in said fourth disc through which further indicia on said third disc is viewable, and indicia associated therewith thereby to determine Soil Group Index.

7. A dial computer for determining soil classification and soil group index in accordance with the AASI-IO system, comprising:

a. a base member having an arcuate percentage scale,

for indicating the percentage of soil passing through a selected sieve,

. three dials of progressively decreasing diameter superimposed and rotatably mounted on said base member and comprising a first Classification Index dial mounted adjacent said base member, a multiple scale dial mounted adjacent said first Classification Index dial, and a topmost second Classification Index dial mounted adjacent said multiple scale dial,

0. said first Classification Index dial having an arcuate peripheral cutout defining a soil percentage indicator exposing said base member therethrough for indicating the percentage of soil passing through said selected mesh sieve,

a window adjacent said cutout and a second window circumferentially spaced therefrom exposing soil classification data on said base member,

a plasticity index indicator adjacent said window having a pointer directed at said multiple scale dial, and

a classification index disposed about the exposed face indicating soil groupings and subgroupings,

d. said multiple scale dial having plasticity index scales,

a liquid limit scale, and,

a percentage scale indicating the percentage of soil passing through another selected mesh sieve,

a window inwardly of the periphery thereof,

a first indicator adjacent said window directed toward said first Classification Index dial, and,

a second indicator adjacent said window directed toward said second Classification Index dial; and,

e. said second Classification Index dial having an arrow directed toward the liquid limit and mesh scales on said multiple scale dial for indicating either the liquid limit or percentage of soil passing through a selected mesh sieve, and,

a classification index about the periphery of said dial indicating soil groupings and subgroupings,

whereby orientation of said dials in accordance with soil data disposes said first and said second indicators toward said first and said second Classification Indexes, thereby to determine a common soil classification index with said indicators.

8. The dial computer of claim 7 wherein the percentage scale on said base member is color-keyed to the plasticity index scales on said multiple scale dial, and further including color-keying on said base member in conjunction with color-shading of said liquid limit and mesh scales on said multiple scale dial to quickly determine the scale to which said arrow on said second Classification Index dial will be directed 9. The dial computer of claim 7 further including a selected mesh scale on the reverse face of said first classification index dial and wherein said base member includes an arcuate window through which said dial is viewable and further includes a series of plasticity index and liquid limit scales radially arranged adjacent a pair of radially disposed windows in said base member through which numerical data are visible on the reverse face of said first Classification Index dial, thereby to determine the Group Index.

Claims

1. A dial computer for determining soil classification comprising: a plurality of superposed discs mounted for relative rotation, said discs including a topmost disc provided with said classification categories thereon, a second disc therebeneath of greater diameter then said topmost disc and having a window therethrough outwardly of said topmost disc, a third disc provided with said soil classification categories thereon disposed beneath and of greater diameter than said second disc, portions of said third disc being viewable through said second disc window, said third disc having first and second windows therein in circumferentially spaced relation and outwardly of said second disc periphery, said third disc further having a notched arcuate cutout on the disc periphery, with said cutout disposed adjacent said first window, a fourth disc disposed beneath said third disc, portions of said fourth disc being viewable through said first and second windows and cutout in said third disc, and, scales on said discs correlated with said windows and said cutout whereby determined soil classifications are indicated on said topmost and third discs for engineering and construction purposes.

4. The dial computer of claim 1 further including a third window adjacent said second window in said third disc, said third window being at a different radius from that of said second window, thereby to expose a different portion of said fourth disc.

7. A dial computer for determining soil classification and soil group index in accordance with the AASHO system, comprising: a. a base member having an arcuate percentage scale for indicating the percentage of soil passing through a selected sieve, b. three dials of progressively decreasing diameter superimposed and rotatably mounted on said base member and comprising a first Classification Index dial mounted adjacent said base member, a multiple scale dial mounted adjacent said first Classification Index dial, and a topmost second Classification Index dial mounted adjacent said multiple scale dial, c. said first Classification Index dial having an arcuate peripheral cutout defining a soil percentage indicator exposing said base member therethrough for indicating the percentage of soil passing through said selected mesh sieve, a window adjacent said cutout and a second window circumferentially spaced therefrom exposing soil classification data on said base member, a plasticity index indicator adjacent said window having a pointer directed at said multiple scale dial, and a classification index disposed about the exposed face indicating soil groupings and subgroupings, d. said multiple scale dial having plasticity index scales, a liquid limit scale, and, a percentage scale indicating the percentage of soil passing through another selected mesh sieve, a window inwardly of the periphery thereof, a first indicator adjacent said window directed toward said first Classification Index dial, and, a second indicator adjacent said window directed toward said second Classification Index dial; and, e. said second Classification Index dial having an arrow directed toward the liquid limit and mesh scales on said multiple scale dial for indicating either the liquid limit or percentage of soil passing through a selected mesh sieve, and, a classification index about the periphery of said dial indicating soil groupings and subgroupings, whereby orientation of said dials in accordance with soil data disposes said first and said second indicators toward said first and said second Classification Indexes, thereby to determine a common soil classification index with said indicators.

8. The dial computer of claim 7 wherein the percentage scale on said base member is color-keyed to the plasticity index scales on said multiple scale dial, and further including color-keying on said base member in conjunction with color-shading of said liquid limit and mesh scales on said multiple scale dial to quickly determine the scale to which said arrow on said second Classification Index dial will be directed.