DE7618146U1 - DEVICE FOR DETERMINING THE CAPACITY OF FINE SOILS - Google Patents

Description

VONKREISLER, SCHÖNWALD MEYER EISHOLD FUES FROM KREISLER KELLER SELTING

PATENTANWÄLTE ,, ι -i · Dr.-Inq. by Kreisler "t" 1973

Registration term ^a

Dr.-Ing. K. Schönwald, Cologne

CENTER DE RECHERCHES ROUTIERES Dr-Ing. Th. Meyer, Cologne

Dr.-Ing. K. W. Eishold, Bad Soden

Avenue d 'Auder ghem, 49, Dr. J. F. Fues, Cologne

Etterbeek, Belgium Dipl.-Chem. Alek von Kreisler, Cologne

Dipl.-Chem. Carola Keller, Cologne Dipl.-Ing. G. Selting, Cologne

Sg-Is 5 COLOGNE l 4th June 197 6

DEICHMANNHAUS AT THE HAUPTDAIiNHOF

Device for determining the load-bearing capacity of fine soils

The invention relates to a device for determining the Carrying capacity of fine soils.

The load-bearing capacity of a soil is usually determined by measurement the resistance of the soil to indentations is determined under precisely defined conditions. The carrying capacity is usually represented by the California Load Index (C.B.R.), which is the ratio between the pressure generated by a standardized cylindrical punch that is advanced at a certain speed and the pressure required to make the same stamp on a standard material under the same conditions, indicates. This ratio is expressed in% *

The inventive device allows the resistance to determine the protection against indentation by hitting a fine floor. The device becomes such operated to establish a direct relationship between the measured indentations and the Californian carrying capacity

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provides the ability index, regardless of the nature of the soil examined (from loam to fine sands). This relationship is valid as long as the depth of the impression per stroke is less than 40 mm and the total penetration depth is less than 1.20 m.

The device according to the invention is characterized in that a base plate that can be fixed to the floor has a hole through which a first rod, at the lower end of which there is a stamp, protrudes, that above the first rod, a second rod is arranged, which is in its lower end Area carries an anvil and in its upper area an elastic stop and serves as a guide for a drop hammer, which is freely movable between the elastic stop and the anvil and falls due to its mass on the anvil that the punch has a cylindrical body and at the bottom The end is pointed at an opening angle of approx. 60 °, and that the mass of _{the drop hammer f} the height of fall and the yi.u5L.fc: QuciouauitLöIlSCiiö d <ö3 Ctcinpclc cL.lc the following Gl ^ i-

chung: 95. <^^ <fiO5 kg / cm.

Preferably the first rod is attached to one or more extension rods. The vertex angle of the The tip of the punch and the equation given ensure that there is a clear relationship between the mean Penetration Depth and the Californian Load Index C.B.R. exists, largely independent of the nature and the condition of the fine soil.

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In the following an embodiment of the invention with reference to the single figure of the drawing explained in more detail.

In the drawing, an impact device according to the invention is shown. There are four feet on the base plate 1 2, which are pressed into the ground to secure the device tightly to the ground. The base plate is also provided with handles 3. In the base plate 1 there is a hole 4 through which a rod 5, at the a punch 6 is attached at the lower end, passes through it. The rod 5 is substantially at right angles to Surface of the base plate 1. The rod 5 can have several separate extension tubes, the ends of which are juxtaposed can be screwed to achieve the required length

ten. f

At the upper end of the rod 5 an impact rod 7, which runs practically coaxially to the rod 5, is screwed. j j ± m lower Beiciuu Jii. SLangs. 7 is located in a> ^lmhnR R- \

while an elastic stop 9 is attached to the upper end of this rod. There is a drop hammer on rod 7 10 guided, which is freely displaceable along the rod 7 between the elastic stop 9 and the anvil 8 and can fall freely on the hammer as a result of gravity.

The punch 6 consists essentially of a cylindrical body 60 with a certain diameter, a projection 61, with which the approach can be attached to the end of the rod 5, and a cone 62, the apex angle of about 60 ° amounts to. The tests carried out have shown

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that the choice of this angular value allows a clear and unique relationship between penetration to put the stamp in the ground and the California index, which is valid for all fine soils.

The invention shows that the mass M of the drop hammer 10, the falling height h of the drop hammer and the maximum cross section A of the punch 6 by the following relationship with each other are connected:

95 ^ ^ <105 kg / cm.

The device also has a telescopic slat 11 which is mounted practically at right angles to the surface of the base plate 1. In the illustrated embodiment, there is the staff 11 from a slider 12, which is a measuring graduation 13 carries and slides along a support 14, on which it is at any height by means of a screw 15 can be fixed.

Using the device is very easy. After the device has been set up and fixed in place, the Telescopic slat 11 such that the zero point of the measuring rod 13 with the drop hammer 10 resting on the anvil 8 the height of a marking line engraved in the drop hammer 10 is brought. Now the drop hammer becomes raised to the upper stop and then dropped in free fall cuf the anvil 8. this happens several times in a row in a regular sequence (e.g. about 30 χ per minute) until a first marking line on the rod 5 is below the level of the base plate 1 has sunk. The number of up to that point

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The blows carried out are noted and the penetration of the stamp into the ground can be read on the scale 13 will.

This process is then repeated until the the last marking line has sunk below the level of the base plate.

When you have penetrated to a greater depth in this way, you screw after the drop hammer 10 has been stopped, the impact rod 7, taking care that the rod 5, at which the in the ground penetrated punch 6 is attached, does not rotate. Then an extension rod is attached to the top of the Rod 5 is screwed on and the striking rod 7 is screwed onto the upper end of the extension rod. so the drop hammer 10 is also reassembled and the telescopic slat 11 readjusted in the manner described above, Now begins the procedure of npiipiti nnrJ described above, one adds so many extension bars one after the other as necessary to obtain the required depth of penetration.

Based on the individual readings taken one after the other, the mean penetration depth per impact is now determined, which can be clearly assigned to a value of the C.B.R.-index for each stratum. The mean depth of penetration can be determined for each layer in the following way. The differences between the consecutive Readings of the depth of penetration are recorded in relation to the number of hits. the Quotient between each difference and the corresponding one

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The number of blows indicates the average depth of penetration per blow. As stated above, the opening angle ensure the Tip of the punch 6 and the aforementioned relationship between the mass M of the hammer, the height of fall h and the maximum cross-sectional area A of the punch the clear relationship between the mean penetration depth and the CB.R. index, regardless of the nature and the State of the fine soil. The only requirement is that the penetration depth per impact and the total depth are each less than 40 mm or 1.20 m.

The conversion of the penetration depth per impact into the CBRIndex is given by the following equation ^{for a punch of 5 cm 2:}

log CBR = - (1.31 - 0.09) log χ + (2.58 to 0.11).

Here, χ is the depth of penetration per impact, expressed in millimeters. For example, there is a penetration depth χ = 16 mm in this way a C.B.R.-Ind3c of 10% and for a penetration depth χ = 12 mm a C.B.R.-index of 15%. The C.B.R. values expressed by the equation log C.B.R. = -1.31 log χ + 2.58 represent the C.B.R. indices, with a precision interval whose limits are 1.4 C.B.R. and 0.7 C.B.R. at the level of probability of 0.95.

The determination of the C.B.R.-indices for the different Laying a soil can be carried out directly and immediately using the impact device according to the invention will.

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Claims (4)

Expectations 1. Device for determining the load-bearing capacity of fine soils, characterized in that a base plate (1) which can be fixed to the ground has a hole (4) through which a first rod (5), at the lower end of which there is a stamp (6) , protrudes through that above the first rod (5) a second rod (7) is arranged, which carries an anvil (8) in its lower area and an elastic stop (9) in its upper area and serves as a guide for a drop hammer (10 ) is used, which is freely movable between the elastic stop (9) and the anvil (8) and falls due to its mass on the anvil that the punch (6) has a cylindrical body (60) and at the lower end with an opening angle of approximately 60 °, and that the mass M of the drop hammer (10), the height of fall h and the largest cross-sectional area A of the punch (G) satisfy the following equation: 95 ^ ^ ~ ^ 105 kg / cm. 2. Apparatus according to claim 1, characterized in that parallel to the second rod (7) is a telescopic slat (11) which carries a length scale (13). 3. Apparatus according to claim 1 or 2, characterized in that the first rod (5) consists of several detachable from one another Extension tubes is made. 4. Device according to one of claims 1 to 3, characterized in that that the punch (6) is detachable from the first rod (5). 761H46 10/7/76