DIN 18134平板载荷试验规程(德国)

DEUTSCHE NORMSeptember 2001

Determining the deformation and strengthcharacteristics of soil by the plate loading test

ICS 93.020

Baugrund, Versuche und Versuchsgeräte – Plattendruckversuch

{

18134

Supersedes

January 1993 edition.

In keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.

Contents

Page

Page

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21234

Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Normative references . . . . . . . . . . . . . . . . . 2Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Designation . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3 3 3 3 4 4 4 5 6

7.3

5Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . .5.1General . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.2Reaction loading system . . . . . . . . . . . . . .5.3Loading plates . . . . . . . . . . . . . . . . . . . . . .5.4Loading system . . . . . . . . . . . . . . . . . . . . .5.5Load-measuring device . . . . . . . . . . . . . . .5.6Settlement-measuring device . . . . . . . . . .5.7Ancillary equipment . . . . . . . . . . . . . . . . . .5.8Calibration of plate loading apparatus . . .6

Arrangement of settlement-measuringdevice . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.4Preloading . . . . . . . . . . . . . . . . . . . . . . . . . .7.5Loading and unloading . . . . . . . . . . . . . . .7.5.1General . . . . . . . . . . . . . . . . . . . . . . . . . . .7.5.2Determination of strain modulus . . . . . .7.5.3Determination of modulus of subgrade

reaction . . . . . . . . . . . . . . . . . . . . . . . . . . .Evaluation and representation of

results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8.1Load-settlement curve . . . . . . . . . . . . . . . .8.2Calculation of strain modulus . . . . . . . . . .8.3Calculation of modulus of subgrade

reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

6 6 6 6 6 7 7 7 8 8

Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Calibration of plate loading

apparatus . . . . . . . . . . . . . . . . . . . . . 11Normal equations for determiningthe factors to be used in settlement

calculations . . . . . . . . . . . . . . . . . . . . 13

General test conditions . . . . . . . . . . . . . . . . 6

Annex AAnnex B

7Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.1Test area preparation . . . . . . . . . . . . . . . . . 67.2Setting up the plate loading apparatus . . 6

No part of this translation may be reproduced without the prior permission of

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Continued on pages 2 to 13.

Translation by DIN-Sprachendienst.

In case of doubt, the German-language original should be consulted as the authoritative text.

Ref. No. DIN 18134:2001-09

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DIN 18134:2001-09

Foreword

This standard has been prepared by Technical Committee 05.03.00 Baugrund, Versuche und Versuchsgeräteof the Normenausschuss Bauwesen (Building and Civil Engineering Standards Committee).

Amendments

This standard differs from the January 1993 edition as follows:

a) The total thickness of loading plates of 600mm and 762mm in diameter including stiffeners has beenreduced from 110mm to 80mm (cf. subclause 5.3 and figure 2).

b) More detailed requirements for the measuring devices have been specified (cf. subclauses 5.5 and 5.6).c) Specifications for calibration of the plate loading apparatus have been included (cf. Annex A).Previous editions

DIN 18134: 1976-07, 1990-06, 1993-01.

All dimensions are in millimetres.

1Scope

This standard is intended for use in earthworks and foundation engineering, as well as in road construction. Itspecifies a method (‘plate loading test’, for short) which permits the relationship between load and settlement(load-settlement curve) to be determined, the aim being to assess the deformation and strength characteristicsof soil and to determine the strain modulus and the modulus of subgrade reaction.

2Normative references

This standard incorporates, by dated or undated reference, provisions from other publications. These norma-tive references are cited at the appropriate places in the text, and the titles of the publications are listed below.For dated references, subsequent amendments to or revisions of any of these publications apply to thisstandard only when incorporated in it by amendment or revision. For undated references, the latest edition ofthe publication referred to applies.DIN 861-1DIN DIN 4018

DIN EN 10002-3DIN EN 10025DIN EN ISO 7500-1

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ISO 2768-1:1989ISO 2768-2:1989

Gauge blocks – Concepts, requirements and testing

Micrometers – Standard design external micrometers – Concepts, requirements andtesting

Calculation of bearing pressure distribution under shallow foundations

Metallic materials – Tensile testing – Part 3: Calibration of force-proving instruments usedfor the verification of uniaxial testing machines

Hot rolled unalloyed structural steel products – Technical delivery conditions (includesAmendment A1:1993)

Verification of static uniaxial testing machines – Part1: Tension/compression testingmachines – Verification and calibration of the force-measuring system(ISO7500-1:1999)

General tolerances – Part1: Tolerances for linear and angular dimensions without indi-vidual tolerance indications

General tolerances – Part2: Geometrical tolerances for features without individual tol-erance indications

3

3.1

Concepts

Plate loading test

Test in which a load is applied in increments to a soil sample using a circular loading plate and a loading device,released in decrements, and the entire process is repeated. The average normal stress below the plate, s 0, isplotted against the settlement, s , for each load increment so as to obtain a load-settlement curve.

3.2Strain modulus

The strain modulus, E V , is a parameter expressing the deformation characteristics of a soil, and is calculatedtaking values from the load-settlement curve obtained from the first and second loading cycle, from the gradientof the secant between points 0,3·s 0max and 0,7·s 0max (cf. subclause 8.2).

3.3Modulus of subgrade reaction

The modulus of subgrade reaction, k s , is a parameter expressing the elastic reaction of a soil under a surfaceload. It is determined on the basis of the load-settlement curve obtained from the first loading cycle(cf. subclause 8.3).

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DIN 18134:2001-09

4Designation

Test DIN18134 – 300

Designation of a plate loading test using a loading plate with a diameter of 300mm:

5

5.1

Apparatus

General

The following equipment is required.a) Reaction loading system.

b) Plate loading apparatus, consisting of a loading plate, an adjustable spirit level, and a loading systemwith hydraulic pump, hydraulic jack assembly and high-pressure hose.

c) Devices for measuring the load applied and the settlement of the loading plate at right angles to theloaded surface.

d) Programmable pocket calculator, suitable for calculating quadratic equations.

5.2Reaction loading system

The reaction loading system shall produce a reaction load which is at least 10 kN greater than the maximumtest load required, and may be a loaded truck or trailer or any other object of sufficient mass.

5.3Loading plates

Loading plates shall be made of grade S355J0 steel (cf. DINEN 10025) and have two handles. They shall bemachined to class mk tolerances as in ISO2768-2 and to the flatness tolerances specified in figures 1 and 2.Loading plates with a diameter of 300mm shall have a minimum thickness of 25mm. They shall have an openingof rectangular form to receive the stylus of the settlement-measuring device.

View A

Key to figure

1Centring pin to hold the strain gauge2Handle 3Hole circle

Figure 1:300mm loading plate

Loading plates with diameters of 600mm and 762mm shall have a minimum thickness of 20mm and beprovided with equally spaced stiffeners, each 20mm wide, with even upper faces parallel to the plate bottomface to allow the 300mm plate to be placed on top of it. Centring pins and clamps, if necessary, shall beprovided to hold the upper plate in position (cf. figure 2).

The plate diameter shall be subject to a tolerance of 0,5mm and the plate thickness to a tolerance of 0,2mm.

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DIN 18134:2001-09

Section A-A (reduced anddiagrammatic)

Key to figure1Centring pin

2300mm loading plate3Stiffener

4Attachment hole for handle

Figure 2:600mm or 762mm loading plate

5.4Loading system

The loading system shall consist of a hydraulic pump connected to a hydraulic jack via a high-pressure hosewith a minimum length of 2 m. The system shall be capable of applying and releasing the load in stages.For the pressure to be properly applied, the hydraulic jack shall be hinged on both sides and secured againsttipping. The pressure piston shall act through at least 150mm.

The height of the jack during operation shall not exceed 600mm. In order to compensate for differences in theheights of the vehicles used as reaction loads, elements shall be provided that allow the initial length of thepressure piston to be increased to at least 1000mm. Suitable means shall be provided to prevent buckling ofthese elements.

5.5Load-measuring device

The load on the plate is best measured by means of a strain gauge with a limit of error of 1%, which shall befitted between loading plate and piston.

The resolution of the gauge shall be at least 0,001MN/m2 for 300mm loading plates and at least 0,0001MN/m2for 600mm and 762mm loading plates.

The resolution of the force-measuring system shall be equivalent to that of the strain gauge.The above requirements shall apply for temperatures from 0 °C to 40 °C.

5.6Settlement-measuring device

For measuring the settlement of the loading plate, a contact arm assembly as shown in figure 3 shall be used.This consists of a frame supported at three points, a vertically adjustable, torsion-proof, rigid contact arm, anda displacement transducer or dial gauge. The contact arm is connected to the frame via a fulcrum (cf. figure3 a))or a linear bearing (cf. figure3b)). The minimum distance between the supports and the centre of the loadingplate shall be (1500t 5) mm. The h p /h M ratio (cf. figure3a)) shall not exceed2. The assembly shall be capableof being set so that the h p /h m ratio does not change during measurement.

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DIN 18134:2001-09

a) Contact arm assembly with fulcrum

b) Contact arm assembly with slide bearing

Key to figures

1Dial gauge or displacement transducer2Supporting frame3Fulcrum

4Contact arms M , s

Settlement reading

Figure 3:Assemblies for settlement measurement (examples)

The contact arm assembly with fulcrum is only suitable for settlement measurements in depths up to 0,3m. The dial gauge or displacement transducer shall be capable of measuring to an accuracy of 0,04mm forsettlement values up to 10mm and when using a 300mm or 600mm loading plate, and for values up to 15mm when using a 762mm loading plate. It shall have a resolution of at least 0,01mm. The above requirements shall apply for temperatures from 0°C to 40°C.

5.7Ancillary equipment

The following ancillary equipment is required.a) Spade .

b) Steel straightedges, 400mm, 700mm and 850mm long.c) Hand brush.

d) Trowel, spatula, set square, plumb line, folding rule, dry medium sand, gypsum plaster, oil. e) Tarpaulins or similar means of protection against sun and wind.

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5.8Calibration of the plate loading apparatus shall be carried out as specified in Annex A.It is required before delivery and after repair and shall be repeated once a year.

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6General test conditions

The plate loading test may be carried out on coarse-grained and composite soils as well as on stiff to firm fine-grained soils. Care shall be taken to ensure that the loading plate is not placed on particles larger thanapproximately one-quarter of its diameter.

In the case of rapidly drying, equigranular sand, or soil which has formed a surface crust, has been softenedor has been otherwise disturbed in its upper zone, the plate loading test shall be conducted with the disturbedsoil being removed.The density of the soil under test shall, as far as possible, be uniform throughout.

For fine-grained soil (e.g. silt, clay), the plate loading test can only be carried out and evaluated satisfactorilyif the soil is stiff to firm in consistency. In case of doubt, the consistency of the soil under test shall be determinedat various depths up to a depth equal to the diameter of loading plate, d , below ground level.

7

7.1

Procedure

Test area preparation

A test area sufficiently large to receive the loading plate shall be levelled using suitable tools (e.g. steelstraightedge or trowel) or by turning or working the loading plate back and forth. Any loose material shall beremoved.

7.2Setting up the plate loading apparatus

The loading plate shall lie in full contact with the test surface. If necessary, a thin bed of dry medium-grainedsand or gypsum plaster paste shall be prepared to obtain a level surface on which the plate is to be beddedby turning and slightly tapping on its upper face. When using gypsum plaster as bedding material, the plate shallbe greased on its underside. Any excess plaster shall be removed with the spatula before it sets. Testing shallnot begin until the plaster has set.

A spirit level shall be fitted to the upper face of the plate and, when the test area is inclined, adjusted accordingly.The piston of the hydraulic jack shall be placed centrally on, and at right angles to, the loading plate beneaththe reaction loading system and secured against tipping. The minimum clearance between loading plate andcontact area of the reaction load shall be 0,75m for a 300mm plate, 1,10m for a 600mm plate, and 1,30m for a 762mm plate. The reaction load shall be secured against displacement at right angles to the direction ofloading. Care shall be taken to ensure that the loading system remains stable throughout the test.

7.3Arrangement of settlement-measuring device

The contact arm assembly shall be positioned so that its supports are located 1,5m from the centre of theloading plate. The dial gauge or displacement transducer shall be set up vertically (cf. figures3a) and 3b)). When placing the loading plate, care shall be taken to ensure that the stylus of the contact arm can be passedinto the rectangular opening without hindrance and positioned centrally on the plate.

The settlement-measuring device shall be protected from sunlight and wind. Care shall be taken to ensure thatthe device and the reaction loading system are not subjected to vibration during the test.

7.4Preloading

Prior to starting the test, the strain gauge and the dial gauge or displacement transducer shall be set to zeroand the plate preloaded for about 30seconds. The load applied shall correspond to a normal stress of0,01MN/m2 when using a 300mm or a 600mm plate and to a normal stress of 0,005MN/m2 when using a762mm plate.

The reading of the gauge or transducer at this load shall be taken as zero reading.

7.5Loading and unloading

7.5.1General

The maximum load required or the maximum settlement is governed by the objectives of the test, as well asby the expected strength and deformation characteristics of the soil and the size of the loading plate.7.5.2Determining the strain modulus

To determine the strain modulus, E V , the load shall be applied in not less than six stages, in approximately equalincrements, until the required maximum normal stress is reached. Each increase in load (from stage to stage)shall be completed within one minute. The load shall be released in stages, to 50% and 25% of the maximum

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DIN 18134:2001-09

load and then to the load corresponding to the zero reading. Following that, a further (2nd ) loading cycle shallbe carried out, in which the load is to be increased only to the penultimate stage of the first cycle.

When testing soil, the time interval between the application of each load increment shall be two minutes, theload being held constant during this period. For subbase testing, one minute is sufficient. The gauge readingshall be recorded at the termination of each loading stage (cf. subclause 9.1 and tables 1 and 2).

To determine the strain modulus for design calculations in road construction, a 300mm loading plate shall beused and the load increased until a settlement of 5mm or a normal stress below the plate of 0,5MN/m2 isreached. If the required settlement is reached first, the normal stress measured at this stage shall be taken asmaximum stress.

For a 600mm loading plate, a settlement of 8mm or a normal stress of 0,25MN/m2, and for a 762mm loadingplate, 13mm or 0,2MN/m2 shall be reached.

If a test proceeds in an unexpected manner (e.g. if the loading plate tips or sinks rapidly), the soil at the testsite shall be dug up to a depth equal to the plate diameter. If stones are encountered, or if the soil is of less thanstiff consistency, this shall be recorded.

For soils of low particle strength (e.g. volcanic scoria) and where a rapid deformation of the soil as the loadingincreases indicates imminent failure, testing shall be terminated at lower settlement or normal stress values.If, during the loading cycle, a higher load than intended is inadvertently applied, this load shall be maintainedand a note made in the records.

NOTE:In order to check the results obtained from the second loading cycle, a third cycle may be carried outto the same maximum load, this being applied immediately after the second loading stage, without anyfurther intermediate stages.7.5.3Determining the modulus of subgrade reaction

In order to determine the modulus of subgrade reaction, k s , for use in the design of road and airfield pavements,a 762mm loading plate shall be used. A stress of 0,005MN/m2 shall be maintained until the rate of settlementof the plate is less than 0,02mm/min. The load shall then be applied in increments producing normal stressesof 0,04MN/m2, 0,08MN/m2, 0,14MN/m2, and 0,2MN/m2, with the load being maintained at each stage untilthe rate of settlement of the plate becomes less than 0,02mm/min. The load may be released with one inter-mediate stage at 0,08MN/m2.

NOTE:It should be taken into account that the modulus of subgrade reaction for use in the design of founda-tions on an elastic base is a function of the loaded area (cf. DIN4018).

8

8.1

Evaluation and representation of results

Load-settlement curve

For each load increment, the average normal stress, s 0, and the associated settlement reading, M , shall berecorded (cf. clause 9). For the assembly shown in figure 3b), M shall be taken as the settlement, s , at the centreof the plate. For the assembly shown in figure 3a), s is to be obtained by multiplying the settlement reading,s M , by the factor h P /h M , in accordance with equation (1): hP s =s M ë

hM

(1)

The stress shall be plotted against the settlement, as shown in figure4. A smooth curve shall be drawn throughthe measuring points for each cycle, the loading and unloading cycles being identified by directional arrows.The test report shall include the following information:a) location of test site;

b) diameter of loading plate;

c) type of settlement-measuring device used, including h P /h M ratio, if relevant;d) type of soil;

e) type of bedding material below the plate;f) weather conditions;

g) time and date of measurements;h) time of start and completion of test;

i) any unusual observations made during the test;

j) dial gauge readings and corresponding normal stresses;k) load-settlement curves;

l) description of the soil conditions below the plate after testing.

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DIN 18134:2001-09

8.2Calculation of strain modulus

Calculation of the strain moduli of the first and the second loading cycle shall be based on smooth load-settlement curves. These shall be expressed by calculating the settlement, s , at the centre of the loading plateusing equation (2):

2s =a 0+a 1ës 0+a 2ës 0

(2)

where

s 0

a 0, a 1, a 2

is the average normal stress below the plate, in MN/m2; are factors, inmm/MN2/m4.

For determining the factors, a value of s equal to zero shall be ignored.

For calculating the factors from the results obtained in the loading mode, the normal equations given in AnnexB shall be used.

If a computer programme is used, it shall be checked using the calculation examples given in subclause 9.1.The strain modulus, E V , in MN/m2, shall be calculated using the following equation:

E V r mm;

s 02.

(3)

k s , in MN/m3, shall be calculated using the following equation:k s s 02; s mm (cf. figure 5).

(4)

9

Test DIN18134 – 300

(h P h P /M See tables 1 to 3, and figure 4.

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DIN 18134:2001-09

Table 1:Measured values for first loading cycle and unloading cycle

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Loading stage

no.

Load, F , in kNNormal stress,

s 0, in MN/m2Settlement reading,

s M , in mm

Settlement,

s ,

of loading plate,

in mm

Table 2:Measured values for second loading cycleLoad, F , in kN

Normal stress,

s 0, in MN/m2

Settlement reading,

s M , in mm

Settlement,

s ,

of loading plate,

in mm

Loading stage

no.

Table 3:Results of loading test

Parameter t 0max (MN/m2) a 0 (mm)a 1 (mm/(MN/m2)) a 2 (mm/(MN2/m4))

1,5ër

EV (MN/m2) (a 1+a 2ës 0max )

E V 2E V 1

1st loading cycle

2nd loading cycle

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DIN 18134:2001-09

Normal stress, s 0, in MN/m2

S e t t l e m e n t , s , i n m m

Loading stage no.

Load, F , in kNNormal stress,

s 0, in MN/m2Settlement,

s ,

of loading plate, inmm

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Normal stress, s 0, in MN/m2

S e t t l e m e n t , s , i n m m

Tangent atpoint ofinflexion

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DIN 18134:2001-09

A.3.2Settlement-measuring device

In addition to the equipment described in subclause 5.6, the following is required.

a) Micrometer as in DIN863-2 or DIN861 gauge blocks of grade 2 with nominal lengths from 1mm to15mm.

b) Surface , suitable to receive calibration equipment.

A.4Procedure

A.4.1Force-measuring system

The force-measuring system of the plate loading apparatus and the reference gauge shall be mounted centrallyin the frame and subjected to a preload corresponding to a normal stress below the plate of 0,01MN/m2, theload being applied using the loading system of the apparatus.

For calibrating the strain gauge and verifying the loading system, two loading cycles and one unloading cycleshall be carried out, with the load increments selected as a function of the plate diameter (cf. tableA.1). Eachincrease/decrease in load (from stage to stage) shall be completed within one minute. The load shall be releasedin four stages (nos. 6, 4, 2, 1; cf. tableA.1). When both loading and unloading, the interval between the end ofone stage and the start of the next shall be two minutes, during which time the load shall be maintained. Eachload shall be set at the force-measuring system and the reference gauge reading recorded.

Calibration shall be carried out at an ambient temperature between 10°C and 35°C (cf. DINEN ISO 7500-1). The relative accuracy error, q , as a percentage, is given by: Fi –F

q =100 Fmax

where F i is the force indicated by the force-measuring system, in kN;F is the force indicated by the reference gauge, in kN;

F max is the maximum load required for the test, in kN (loading stage no. 8; cf. table A.1).The limit of error of the force-measuring system shall be as specified in subclause 5.5.

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(A.1)

Table A.1:Load increments as a function of plate diameter

Diameter of loading plate, inmm

300

Load, F , in kN

Normal stress,

s 0, in MN/m2

Load, F , in kN

600

Normal stress,

s 0, in MN/m2

Load, F , in kN

762

Normal stress,

s 0, in MN/m2

Loading stage

no.

1. 2. 3. 4. 5. 6. 7. 8.

Copyright Deutsches Institut Fur Normung E.V.

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For calibration, three zero settings shall be carried out and one series of measurements taken for each zerosetting. Each series shall comprise at least five measurements taken at approximately equal intervals along themeasuring range of the instrument to be calibrated. Measurements shall start at the maximum calibration rangeand include the ranges up to 10mm and up to 15mm.

The readings of the dial gauge or displacement transducer for the three measurement series shall be recorded.Calibration shall be carried out at an ambient temperature between 10°C and 35°C (cf. DINEN ISO 7500-1). The temperature at which the calibration is carried out shall be recorded.

If one of the values indicated by the dial gauge or displacement transducer differs from the micrometer readingor the nominal value of the gauge block by more than 0,04mm, the settlement-measuring device shall beadjusted in accordance with the manufacturer’s instructions and the calibration repeated.

A.5Calibration report

The calibration report shall include the following information.a) name and address of client;

b) details of the apparatus calibrated (manufacturer, type, identification number, year of manufacture);c) calibration temperature;d) date of calibration;

e) name of calibration body and person responsible for calibration;f) calibration certificate number of reference instruments used;g) general condition of apparatus before calibration;

h) deviations of loading plate and contact arm assembly dimensions from specified dimensions;i) h P /h M ratio of contact arm assembly;

j) accuracy error of force-measuring system, as a percentage;k) accuracy error of settlement-measuring device, inmm; l) calibration results.

Annex B

Normal equations for determining the factors to be used in settlement calculations

For calculating the factors for equation (2) from the results obtained in the loading mode, the following normalequations shall be used:

n n n

2=a 0ën +a 1s 0i +a 2s 0s i i

i =1 i =1 i =1

77

7

(B.1)

n n n n

2+a 3=a 0s 0i +a 1s 0s 0s i i 2i

i =1 i =1 i =1 i =1

777

7

ës 0i

(B.2)

2+a 342a 07s 0i 17s 0i +a 27s 0i =7s i ës 0i ës 0i i =1 i =1 i =1 i =1

n n n n

(B.3)

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Copyright Deutsches Institut Fur Normung E.V.