Problems between soil and construction machinery with special reference to field compaction

Journal of Terramechanics, Vol. 29, No. i, pp. 35-55, 1992.

Printed in Great Britain.

0022-4898/9255.00 + 0.00 Pergamon Press Ltd (~) 1992 ISTVS

PROBLEMS B E T W E E N SOIL AND C O N S T R U C T I O N M A C H I N E R Y WITH SPECIAL R E F E R E N C E TO FIELD COMPACTION* HIROAKI FUJIIt

INTRODUCTION THIS paper presents a brief review of compaction problems in the construction field, and of the topics concerning construction machinery, based on Session 5B of the 10th International Conference of International Society for Terrain-Vehicle Systems. The papers dealing with the problems between soil and construction machinery delivered during this session covered a broad subject area. There were 11 papers, which can be grouped roughly into four categories according to the viewpoint of their objectives. Four papers concerned compaction [1-4], three papers discussed underground machines [5-7], two papers treated loaders [8, 9], and two papers dealt with other subjects [10, 11]. Most of the papers were analytical as well as experimental in their coverage. Since the subject of compaction was treated in four papers, its problems will be reviewed first. Then the other papers will be introduced. Compaction is viewed differently by different people. In agriculture the problem is how to avoid compacting the field, and in construction the problem is how to compact in the field effectively. The principles are the same although the approaches are contradictory. The construction issue will be discussed here. There are three problems with compaction from the standpoint of construction: (1) Why can soil be compacted? This is a problem of compaction mechanics. (2) How should the soil be compacted? This is determined through the methods employed, by equipment used and also by costs. (3) How much is the soil compacted? This is the problem of evaluation or quality control. Although these three problems are interrelated, this paper will mainly discuss the mechanism and the evaluation of soil compaction.

*State-of-the-art report presented at the 10th International Conference of the International Society for Terrain-Vehicle Systems,Kobe, Japan (August 1990). tFacultyof Agriculture, OkayamaUniversity,Tsushima,Okayama,Japan. 35

36

H. FUJII MECHANISM OF FIELD COMPACTION

Attempt to clarify The history of compaction is very long. However, scientific research began only in this century. In 1927 Stanton first investigated the relationship between the moisture content and its effect on compaction [12]. Later, Proctor pioneered the concept of optimum moisture content and maximum dry unit weight of soil in 1933 [13-16]. At the Second International Conference of Soil Mechanics and Foundation Engineering in 1948, many papers were presented about soil compaction in the laboratory as well as in the field [17-21]. Most of this research discussed very practically how to compact an embankment to serve as a dam or as a roadway support. Since field compaction is the deformation of soil caused by traveling compaction equipment, we could find the displacement if we knew the relationship between the mechanical system of the compaction equipment and the ground. In this sense, stress in situ has been measured during compaction [22-35] and also in soil under a model roller in the laboratory [36]. Vibratory soil compaction has been studied since the 1930s [37] and investigators have examined not only the problem of compaction but also in soil dynamics [12, 22, 38-42]. Lewis [43] discussed the relationship between the frequency of a vibratory roller and the soil density. Hefer [2] reviewed the effect of compaction with and without vibration, and in vibratory compaction with different frequencies as shown in Fig. 1. This diagram presents the relationship between the number of roller passes and the dry density. Tests are carried out to determine the influence of vibratory compaction on trafficability for an off-road truck (gross weight 132 kN). The maximum dry density is reached by compaction with an amplitude of 1.6 mm, using a frequency of vibration of 28 Hz. Stress distribution and displacement in a compact layer Measurements of stress and/or displacement in situ at depth are few in number. D'Appolonia et al. [26] have investigated the density, the stress in situ and the acceleration at depth for a uniform dune sand being compacted by light-weight vibratory rollers. The effect of compaction is observed to 1.5 m below the surface. However, the appropriate spreading depth is recommended as 55 cm.

o

without vibration 28 Hz

•

36

•

" • 1,9'

Hz

~" 1.8• C •1~ 1.7• "0 1 . 6 1.5 1.4

4

6

number of roller passes

Fro. 1. Change of dry density of the soil by rolling at different frequencies (after Keffer [2]). .7•

•

PROBLEMS BETWEENSOILAND CONSTRUCTIONMACHINERY

37

Fujii et al. [27-35] carried out full-scale compaction tests and measured the stress distribution in several soils being compacted with various types of compaction equipment. They also measured the qc (cone index) in the compacted layer with depth. The qc at 20 or 30 cm below the surface after compaction was the same as before compaction. Since the dynamic added stress in situ at such a depth was about 200 kPa, they concluded that stress less than 200 kPa did not affect compaction for those soils. Ishihara and Nakamura [3] show the distribution of the stress and the acceleration in situ under a vibratory roller (176 kN) and under a "towed huge vibration plate tamper", of their design (gross weight 127 kN, dimension of plate L3.5 m, B2.5 m, vibration force 410 kN, frequency 10 Hz, amplitude 1.0 cm) as shown in Fig. 2. They call this the Mammoth Vibro Tamping method, or MVT. The acceleration and the stress in situ while compacting against depth are shown in Fig. 3, which presents results of the compaction of coarse grained soil using both the MVT method and a vibratory roller. The magnitudes of acceleration and of stress in situ by the tamper are quite a bit larger, and propagate much deeper, than those caused by a conventional vibratory roller. The densities at 0.5 and 1.0 m with the new equipment are larger than with the conventional vibratory roller. This behavior occurs because the flat plate of the tamper cover has a larger area than does the roller, whose contact area is line-like. Moreover, the failure zone, which is generated along t-,__A:_,

NnarJ=tnr r ~ h i n

. . . .

Generatc

~rator MVT unit

ro~rs

FIG.2. Dimensionsof MVT equipment (after Ishihara et al. [3]). Maximum acceleration a s (g)in soil

o

a -2

,2

/ o MVT

~ n VibrationRoller

Soil pressure P (kN/m 2) 0

400

800

~-2

-3 -3 FIo. 3. Transferbehavior of compactionforce (after Ishihara et al. [3]).

38

H. FUJII

the plate because of the lack of bearing capacity, must be smaller than the contact area. Therefore the ratio of the area of the failure zone to the contact area for the tamper must be much smaller than that for the roller.

Theoretical approach Theoretical approaches to the mechanism of compaction are rather few and fewer than that of the operation of the field equipment. This is because field compaction of soil is affected by many factors such as: (1) compaction equipment (types, efficiency); (2) the characteristics of the soil; (3) problems of the boundary region, where the compaction equipment moves on the soil; (4) performance. In these problems, the third issue must be handled by terramechanics. The boundary region problems include those of the bearing capacity problems of soil, the contact pressure or the slippage equipment, the traveling velocity and the dynamic properties of ground, etc. These variables are not independent. In order to explain the process of field compaction, we should establish the formula which would present exactly the relationship between the supply and consumption of the energy involved in the process of compaction. This is very difficult. However, there have been several approaches to clarify the mechanism of compaction which consist of making rather simple models of this phenomenon. There are two approaches: (a) models of the mechanics of continuum; (b) models of the mechanics of particles. Each approach is considered from both a static and a kinetic viewpoint. Between the ground and the compaction equipment there occurs a dynamic force from the impact or vibration due to the irregularity of the ground surface or the transmission of the dynamic forces from the engine of the equipment. Moreover, a vibratory roller generates enforced vibration. Those forces act as a dynamic force to the ground; consequently, we must solve a complicated wave equation in the strict sense [30]. To simplify problems, classical continuum mechanics has been used on the assumption that the dynamic load is static. In some cases, kinetics has been applied, assuming that the ground and/or a part of the roller is a discrete mass, a spring or a dashpot.

Static approach An application of continuum mechanics. Although various models have been established for stress-strain relationships, the soil is generally considered as an elastic body in classical and analytical approaches. However, a non-elastic model can be used in a numerical approach. Providing that the compacted ground is an isotropic and homogeneous elastic body, the equations of Boussinesq and its derivatives can be applied for the ground. In this case the maximum dynamic load is assumed as a static load, called a quasi-dynamic load [28-30]. Broms and Forssblad [37] have measured the dynamic stresses that occur below various vibratory compactors for a variety of soils. Fujii [30-35] applied the classic theory to the mechanism of generating stresses

PROBLEMS BETWEEN SOILAND CONSTRUCTIONMACHINERY

39

from bulldozers, which are used as compactors for small earth work or for preliminary compaction. The stress variation--time-stress relation on an oscilloscope--in situ by moving a bulldozer along the ground shows shapes similar to random vibration. The bulldozer has crawler tracks which indirectly transmit the load to the ground through the track rollers. Thus, the contact pressure changes according to the configuration of the ground surface or to the rigidity of the ground. This behavior is modeled and analysed using the Boussinesq theory. The analytical stress in situ agrees with the measured values. Numerical analysis. (1) Comparison to the model test. Statical numerical analysis for compaction has been tried using the finite element method (FEM). Yong and his colleagues [44-47] calculated the response of soil according to FEM, under the movement of moving model rollers. The soil was assumed to respond non-linearly on loading and linearly on reloading. Calculated values corresponded to the measured ones fairly well. Using these results, the energy consumption for compaction was also calculated. Kitano and Tokita [48] also tried a test using a rigid model roller (radius 15 cm) on sand (9 = 35°, c = 58.8 kPa), and compared the results to the result of FEM (which assumes soil to be a Drucker-Prager elasto-plastic body). Both predicted and measured results demonstrated the same pattern.

(2) Comparison to the field test. The effect of vibration in compaction is said to be the particle rearrangement from cyclic deformation, with secondary effect from particle vibration, impact or strength repetition [49]. Also, the stress propagation of a vibratory roller is said to follow Boussinesq's equation [37, 50]. Assuming both the above results, Fujii et al. [51, 52] tried to apply FEM to determine the results of a large-scale field test of a vibratory roller (gross weight 149 kN) and a pneumatic-tired roller (255 kN). The quasi-dynamic load of a vibratory roller is calculated as the vibratory force divided by its contact area. The soil was assumed as elastic obeying the nonlinear Duncan-Chang model and the DruckerPrager model. To some extent, good results were obtained concerning the relationship between the number of passes and settlement or density. The elastic deformation, i.e. the rebound of the ground after loading, increases with numbers of passes and settlement decreases. These results indicate that the appropriate numbers of passes by the roller must be six to eight. If the ground is not compacted within this number of passes, the spreading depth of the soil layer should be decreased. The effect of strain velocity on soil deformation [53, 54] should be considered for the transient load or vibration load. Considering this effect, the larger load may not necessarily improve the compaction. The kinetic model Particle model. Although various oscillations occur while compacting, the analytical model is usually considered as a two or three-degree-of-freedom equivalent lumped mass-spring-dashpot system for roller and ground. If the roller jumps owing to the hard ground, a non-linear model must be considered. Selig [49], and Yoo and Selig [55] represented a linear, two-degree-of-freedom system for the behavior during compaction by vibratory rollers and performed a series

40

H. FUJII

of field tests. The effects of compaction by a vibratory roller are related to vibration frequency, travel speed, the vertical displacement of the drum during oscillation and the static contact force. The model provides an important tool in understanding the vibratory roller response. Fujii et al. [30, 32] observed that stresses generated in situ by most compaction equipment increase with travel speed. They explained this by using linear two and three-degree-of-freedom systems. They assumed that the irregularity of the ground surface can be represented as a sinusoidal function and that compaction equipment runs on it with constant speed. When a rigid roller runs on fairly rigid ground, such as rockfill materials, the force from the roller to ground is generated in proportion to the square of travel speed. This tendency is more severe for a tamping roller. A pneumatic tire roller, however, generates a larger stress at a speed less than 1 km/h because of the resonance of vibration. In contrast, the stress in situ due to a vibratory roller drastically decreases with increasing travel speed. For a vibratory roller (75.5 kN, travel speed 1.2-6.4 km/h), the maximum effect of compaction occurs at a travel speed of 1.2km/h [49]; lower speeds were not examined. Fekte [56] also mentioned the effect of travel speed of a roller during compaction. Continuum and granular model. A tamper and a rammer are the compaction equipment that use impact energy propagated as a wave resulting from collision with the ground. Since their contact area is much larger compared to a roller with the same width, the effect of compaction must be larger when the dynamic forces from both types of equipment are the same. This impact force propagates as a wave. Scott and Pearce [57] presented an idealized model to illustrate the mechanism of the impact of a falling weight to the ground that is assumed to be an elastic body. Just after the weight makes contact with the ground, an elastic wave is generated, which is determined by the product of the density of soil and the falling speed of the weight. Suzuki and Yamada [58] tried to expand this model to apply to the falling impact of a plastic body. Hata and Tateyama [59] also tried to study this occurrence theoretically by regarding it as a phenomenon of a plastic front propagating in the soil, assuming a rigid-plastic medium. They derived an equation for this model and calculated its use by a method of finite differences. There is an example applying the method of strain energy for a rammer (gross weight 617 N, area 33 x 33 cm) to calculate the impact force [29]. The theoretical stresses in situ using impact force almost correspond to the measured values. Using the distinct element method, Yamamoto et al. [60] studied compaction of rockfill material by vibration. This method is quite new and has promise as a powerful tool for granular material whose gain size is much larger than the contact area of compaction equipment. Remarks

As shown above, the approaches using classical statics or kinetics for soil compaction have been made using many assumptions that have simplified the phenomena. However, numerical analysis can be used for more complicated models and remains a powerful tool for solving these problems.

PROBLEMS BETWEEN SOIL AND CONSTRUCTION MACHINERY

41

The more sophisticated the models, the more parameters are required as input data. Also, to clarify and to predict the mechanism of compaction more exactly, we must know the mechanism of the contact region between ground and compaction equipment. These are the issues that the personnel investigating terramechanics must pursue.

EVALUATION OF FIELD COMPACTION

Properties that change with compaction When compacted, the soil particles become much closer to each other and increase their contact area. Soil behavior properties are changed, and, generally improved. The soil properties changed by compaction can be described as follows; BASIC:

MECHANICAL: Static:

Dynamic:

Density Void ratio Settlement Modulus of deformation Shearing strength Coefficient of subgrade reaction Permeability Acceleration properties Resonant frequency Spring constant Velocity of elastic wave

ELECTRICAL: Transmission velocity of electromagnetic wave Electric conductivity E L E M E N T A R Y PARTICLE: Mass absorption coefficient Thermal neutron density. In these properties, density has been used as an index of soil compaction since the time of Proctor [13-16]. However, in this decade, the nuclear method, or RI method, has become popular particularly for fine soil.

Basic properties Density. To calculate the density, one must know the volume, the weight and the moisture content of a hole excavated in the compacted fill. Each variable is subject to error and takes time and elaborate work, especially for granular materials. Conventional methods to measure the volume of a hole involve the substitution method using water, sand etc. They are affected by the irregular surface of the hole's wall, particularly if the surface consists of granular material. Moisture content has been determined using an electric oven. However, the use of a microwave oven currently prevails. In addition to density, the degree of compaction, which is defined as the ratio of the field density to the maximum density in laboratory tests, is used for compaction control.

42

H. F U J I I

The increment ratio of density (F~) is defined as: Fn

=

(7n

--

70)/]/0

=

7n/70

--

1

(1)

where 70 is the initial density and 7, is the density after the nth traveling roller. There are statistical methods such as the Hill method [61] and the Ohio typical moisture density curve method aided by cone index [62]. These methods have been used for rapid control of soil compaction. Measuring whole mass. The soil densities are sampled discretely in general so that the mean values are calculated from that limited data. By increasing the number of samples, one approaches the true value and finally can attain the whole mass of the compacted layer. Since the soil mass of the compact layer w is constant, we can find its density by measuring its whole volume as follows: 7o = W / V n

(2)

7. = w/v.

(3)

where V~ is the volume after the nth compaction, and V0 is the volume before compaction. Fujii [63] applied this method to rockfill material and obtained valid results. Settlement and void ratio. Since the mass of soil is constant, the result of compaction can be evaluated by measuring the volume change of the layer compacted. If the area of the layer is wide, the lateral movement of soil in the layer can be neglected. Thus, the changes in volume can be found by measuring the magnitude of settlement Sn as follows: Vn

=

A ( t - Sn) = V0(1 - en)

(4)

where Vn tn are the volume, and thickness of the nth layer created by the traveling of the roller, respectively; t and A are the spreading depth and area respectively; en is the settlement ratio, defined S J t ; Vo is the initial volume of the compact layer. Using the relation of equations (1)-(4) the ratio of density increment is described as [64]: r n ~.

En .

(5)

F, calculated by equation (1) from densities and F, by equation (5) from the settlement correspond well for silty gravel, clayey gravel and rockfill material for which settlement is obtained with about 100 measuring points [63]. Garcia et al. [65] tried to find the compaction effect by determining the distribution of voids in fine-textured soil. The degree of saturation is also used for cohesive soil. Mechanical properties Static properties. (1) Strain. Selig [66] tried to determine the strain in soil by using a coil wire strain gage. Eggestad [67, 68] tried to evaluate the compaction effect by measuring the volume of heaving on the soil surface after inserting a steel rod to the layer compacted. Matsumoto et al. examined this in more detail [69].

PROBLEMS

BETWEEN

SOIL AND CONSTRUCTION

MACHINERY

43

(2) Plate bearing test. A plate bearing test is used to control compaction in certain organizations in Japan, Spain, South Africa and Switzerland [70]. Gidding [71] reports that a fully mobile self-propelled plate loading rig has been constructed and has proved successful as a compaction control test. Each test requires only 5 min. This method has also been discussed by others [72, 73]. (3) Cone index. Penetration resistance measured by a Proctor needle or cone penetrometer has been used for quality control of earthwork since Proctor [14]. Cone index shows the rigidity of the ground and is influenced by density as well as by moisture content or soil characteristics. Hence, the compacted ground must consist of both the same soil properties and moisture content [74]. Hendron et al. [75] use the cone index for construction control of a dike. The density of cohesive soil is related to the index properties such as the fines content (passing No. 200 sieves), the Atterberg limits and the unconfined compressive strength. They determined a statistical relationship between the unconfined compressive strength and the degree of compaction. Their qu values are measured by a pocket penetrometer. One of the most effective uses of the cone index is deciding the optimum spread depth of the compacting layer by measuring in the layer with depth. Comparing the index before compaction and after compaction, one can easily determine whether it has been compacted at the targeted depth [63]. Hefer [2] reports the evaluation of trafficability of the vibratory compaction using cone and plate penetrometers. The research area was transformed into an agricultural field through tillage and harrowing. The soil used for this test is a silty sand (optimum water content 11.3%, maximum dry density about 2.11 g/cm3). Not only the sinkage, but also the pressure were measured with penetrometers. Figure 4 shows the results of soil strength measurements. The slope of these curves shows the strength intensity, which weakens after certain sinkages -- about 2-5 cm according to the number of passes, N. And the changing points become deeper with the number of passes. The gradients of each line are almost the same below these points and also almost parallel to the line before compaction. It is predicted that the layer below these changing points is not compacted.

24O 220

B

liy/ ...... 0

10

20

5

30

40

sinkage [cm] FIG.4. Mean values of cone penetrometer measurementsin rolled areas after one to six roller passes (after Heifer [2]).

44

H. FUJII

Ohta et al. [4] have attempted to estimate the constant-volume shear strength at one point from measuring the density in the field. By carrying out consolidation tests and constant-volume shear tests on a soil with two different water contents, the strength/consolidation pressure ratio is approximated as 0.37, in spite of different water contents. The test results are plotted in Fig. 5(a). The upper part shows results of the consolidation test. In the lower part, the shear strength against consolidation pressure is plotted. The constant-volume shear strength of the soil is in proportion to its virgin consolidation pressure, which is related to the soil density. By extrapolating

1.4

r-

in-sJtu overage ~

1.2

___w -

_

'r~4

•

5

o

E 2pt5

~S-~

4

i

~

,~"

8 ',

i',

16

32

i-

-,-

25

-l

N f . W : 48.3' ~* Su 0363 ~,Pa " "

,f/mz

~ . w-44.2.~.

u ~20

64

' ',consolidation __~ " ~ _~ pressure o-v~ ~ ( t f / m 2)

............ estimated strength - -S,..u.-=-3,'~.,If/m2 estimated pre.-consolidation pressure CC,~ = 9 4

0

~ . i~

,,22 ,,,m,

\ W • 40"/.

.~

1.4

48 52

~>, 1.0 N

~0 , ~ l C

0

o ~20

2:

FIG. 5. (a) Estimated average strength of compacted fill (after Ohta et al. [4]). (b) Possible range of strength of compacted fill material (after Ohta et al. [4]).

PROBLEMS BETWEENSOIL AND CONSTRUCTIONMACHINERY

45

the two consolidation curves, the other curves are plotted as shown in Fig. 5(a). Using the soil in situ at a highway embankment, they also carried out unconfined tests. Figure 5(b) shows the estimated preconsolidation pressure and the shear strength. The unconfined compressive strength of the fill material can be estimated from this relationship. As they show, the measurement of density is not only the method of evaluation of compaction but, significantly, also a combination of field data and laboratory data are required to evaluate the embankment for in-service use. (4) Others. Altschaeffle and Lovell [76] tried to predict the behavior of compacted soil using relationships generated from results of the exhaustive tests in both the laboratory and the field.

Dynamic properties. (1) Magnitude of acceleration. Hata and Tateyama [77] tried to determine the degree of compaction by measuring the magnitude of acceleration of a vibratory roller. They found a relationship between acceleration and the density of the soil. Ishihara and Namura [3] tried to control compaction of soil using acceleration, as measured by the equipment on the "towed huge vibration tamper" cited earlier. Figure 6 shows the maximum acceleration and the density against the number of passes. Both curves have the same trend, so that one can use this to evaluate the degree of compaction. They developed equipment to obtain real-time data for compaction control throughout the area. The data from this equipment could be recorded on an IC card and processed by a personal computer in the office. (2) CMV. Forssblad and his colleagues [78-83] noticed that the shape of the acceleration wave of a vibratory roller varies with the rigidity of the ground. Applying this phenomenon, they have developed a new machine called a compaction meter [79]. The meter receives signals from an accelerometer mounted rigidly on a vibrating drum. The accelerometer continuously records the drum vibrations which are analysed with respect to the fundamental frequency and first harmonics of the vibration. The meter value (which they call CMV) given on the display represents mean values for measuring periods of 5 or 30 s. 23

22 ~ . - " - - o

Nagano

18

21

'~.~. 16 f

=, 20 ~

Yan°(1)e e

_ 14I-

"~ 19

~ _

~ "~ 12 I- ~ . , ~ ' ~ ~ E ~_J

"~~18 I17 16 -

" Nagano

~E ~'~10/" . n,,,,=o00 8I-~~'& °il

I

~'

I

I

ouzu

I

130 2 4 8 8 1012 14161820

Number of passes n (time)

=

0

=

=

=

I

i

~

t

I

2 4 6 8 101214181820

Number of passes n (time)

FIG.6. Relationship between maximum acceleration of tamper and dry unit weight (after Ishihara et al. [3]).

46

H. F U J I I

According to some experiments [63, 84, 85], the more the vibratory roller passes, the larger the CMV becomes for silty gravel. This trend coincides with the densities, settlements and plate bearing test values, each as a function of the number of passes. However, for a clayey gravel or a rock material, the CMV decreases suddenly after six or eight passes. If the soil is soft, the decrease might occur due to over-compaction, but this soil is so strong that the surface settlement, or density, does not decrease. Therefore, this phenomenon occurs because the ground has become stronger and forces the roller to jump. CMV when compacting backward is larger than that which occurs when compacting forward. This phenomenon occurs mainly due to the differences in the traveling speed of the roller. The forward traveling speed is larger than the backward speed. The CMV also is affected by the frequency and amplitude of the roller and by the soil properties, the moisture contents, and the conditions below the layer being compacted. (3) Strain rate. Shimazu et al. [86] also tried to evaluate degree of compaction by harmonic analysis of the acceleration wave. They define the strain rate as follows:

V~/V1

Str. R. =

(6)

where V1 is the spectrum of fundamental frequency 1st harmonics fx; Vn is the spectrum of nth harmonics. When the ground is harder, a sinusoidal wave with the frequency of one half of the fundamental one is generated. Therefore the strain ratio for hard ground is defined as:

Str. R.=

(V~ + V'~2)/V'V21 + V~ 2

(7)

where Vi is the spectrum of one-half the fundamental vibration f l ; V" is the spectrum at the frequency of n times that of f~. According to the results of the full-scale tests in a large soil bin using four vibratory rollers (gross weight 52-80 kN), there is correlation between the strain ratio and the degree of compaction for silty sand. (4) Acceleration spectrums ratio. Fujii et al. [63, 84, 85] carried out a full-scale field test using a vibratory roller mounted on a compaction meter (gross weight 149 kN). They measured three components of the acceleration at the axle of the vibratory drum. The accelerometer is set at near the sensor of the compaction meter in order to compare both values. The acceleration spectrum ratio R0~ is defined as follows: = S2/S

(8)

where, R~x is the generalized acceleration spectrum ratio; Sl is the same to V1 which is the spectrum at fundamental vibration; Sn is the spectrum of nth harmonics. For a silty gravel, R~I can evaluate the degree of compaction as well as the density or settlement and can coincide with CMV. However, R0~l cannot evaluate the degree of compaction for a clayey gravel and rockfill material in the same manner as the CMV. Therefore'another R~, such as

PROBLEMS B E T W E E N SOIL A N D C O N S T R U C T I O N M A C H I N E R Y

47

k

R ~ . = {S'a + ~'~ (S, + S'~)}/S]

(9)

n=2

is defined, where St and S~, are the same as V] and V~, respectively. Also R~o, which is derived from the same equation but using the logarithm of their components, is defined. Both R0~ values can be evaluated even for materials coarser than sand and show the same behavior for density or settlement against the number of roller passes. (5) Resonant frequency. Minami et al. [87] and Nakata et al. [88] determined the enforced vibration of compacted ground using a small vibrator and attempted to evaluate the degre of compaction by measuring the change of the resonance frequency in place. (6) Dynamic subgrade reaction. Rugger [89] reported an example of the evaluation using the dynamic response of a plate bearing apparatus using forced vibration. Another example of this method is the calculation of dynamic bearing capacity from the settlement of the ground beneath a plate upon which a pendulum falls from a known height. A compact hammer, which is newly developed in Italy, uses the same principle as above. (7) Mechanical impedance. Sakai and Idehara [90], Tamura and Sakai [1, 91, 92] and Tamura et al. [93], tried to find the change of spring constants of the compacted ground by measuring the mechanical impedance. This changes according to the strength or the rigidity of the ground and is measured by a newly developed apparatus, called an impedance head [1]. (8) Elastic wave properties. There have been attempts to measure the velocity of an elastic wave propagated in the compacted layer. The elastic wave is generated artificially in the field to evaluate the degree of compaction [63]. Takasu et al. [94] developed a new device to apply this development. Electrical properties Takasu et al. [95] tried to evaluate the degree of compaction by measuring the speed propagated by the electromagnetic wave in the compact layer. Soil density is obtained from the velocity of the electromagnetic wave. Moisture content is obtained from the reflection of near-infrared radiation, etc. They conclude this method can determine quantitatively the density or moisture content of the soil. Elementary particle properties A nuclear method or RI method for fine soil is becoming popular. The method has been researched since 1949 [61] and the designation on how to use this method was established in 1971 in the U.S.A. [96]. Gorshi [97] proposed a continuous measurement of road layers with the RI method and Przedechi and Szumski [98] also reviewed the methods. This method reduces the elaborate work and measuring time to 1/10th or less as compared to the conventional substitution method. Moreover, the method is almost non-destructive and eliminates operator differences which might occur during the

48

H. FUJII

measuring process. This method can be used for soil containing more than 50% gravel. However, the procedure requires at least 10 repetitions of measurement for accuracy [63]. A new device for nuclear measurement of granular material has been developed recently in Japan [99]. It consists of two or four symmetrically fixed tubes, which are inserted with a RI source and/or its sensor. Therefore, the densities at depth can be determined. The values measured by the new device correlate well to the density or surface settlement. However, the maximum grain size of the soil must be less than the distance between tubes. Remarks

The things that we want to know are the shearing resistance, compressibility, permeability, long-term stability, etc., of the compacted soil. However, these properties are not evaluated directly or correctly in field. Therefore the density, which is reproducible in a laboratory to the same degree as in the field, is used as an index of evaluation. Many new devices for controlling soil compaction are being developed, and they are very useful. Moreover, the new methods presented here appear promising, although some devices require improvements to perform effectively in the field. The significance of density should never been forgotten as mentioned before. Perhaps, in the future, a better understanding of the role of soil fabric will allow the prediction of in situ behavior. On the other hand, the evaluation of compaction of coarse-grained material has not yet been completely solved. The intensive work of Institute of the Civil Engineering of Ministry of Construction of Japan [1,87, 88,90-95,100] or JSSMFE [99] is producing good results and remains promising. MISCELLANEOUSPROBLEMSBETWEENSOILAND CONSTRUCTIONMACHINERY Loader

Two topics about loaders were introduced in Session 5B. Muro [9] investigated off-road loaders with a weight of 610-1010kN and 7.7-12.0 m 3 bucket capacities at a limestone quarry site [102]. Georgieff et al. [8] presented the digging process of a shovel loader controlled by micro-computer. The loader with 1.5 m 3 volume of bucket has hydrostatic transmissions. Three main movements of the loader, i.e. its running, lifting (lowering) and rotation of its arm, are identified with such gages as running speed, oil pressure, acceleration, torque, force, etc. An original algorithm was created. Computer control prevents the shovel loader from overloading and sharp impacts, which could occur when an unskilled driver is at wheel. The control system reacts four times faster to changes of the work environment in comparison with manual control. Underground machines and others

Goto [6] reported a new method to improve soft ground. A high embankment of 10 m thickness consisting of the soft ground of a paddy field was constructed at Hayashima Interchange, which is the route for Seto ohashi (Seto-great bridge), one of the biggest projects in this century in Japan and which connects Honshu island with Shikoku island. Since surface displacement at the toe could not be tolerated, they

P R O B L E M S B E T W E E N SOIL A N D C O N S T R U C T I O N M A C H I N E R Y

49

improved the site by using the dry jet mixing method (DJM), which is made from a soil-cement-mixture pile 1 m in diameter with a stabilizer. Figure 7 shows a cross section of the test embankment. The horizontal displacement measured at the toe of the embankment is illustrated in Fig. 8. The observed value was 190% larger than that predicted by FEM analysis. The results of check-borings of DJM piles and the cement mixture tests showed that the pH-value of untreated soils ranged from 5-7, i.e. acid that the natural water content was high, and that the target strength had not been achieved. The amount of cement to mix with those soils was increased and target strength was obtained. Using data from the test embankment, the main embankment was constructed safely resulting in less noise than would have occurred with the conventional sand compacton method. Kadota et al. [7] explained the new method of fracturing a rock without blasting. As shown in Fig. 9, this fracturing machine consists of a high pressure tube at the center surrounded by a square-pole-shaped pressurizing medium (rubber wedge) made of elastic material and rounded steel loaders on the four sides. The machine is

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Ac: Alluvial silty clay DJM: Dry jet mixing pile SCP: Sand compaction pile

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Ams: Alluvial silty sand N: N-value of S.P.T. H - 1 to H - 2: Point for measuring horizontal displacement

FIG. 7. Plan and cross-section of Muchiki e m b a n k m e n t (after G o t o [6]).

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FIG. 8. Horizontal displacements (after Goto [6]).

50

H. FUJII Rubber wedge

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inserted into a borehole and provides high liquid pressure which makes the rubber wedge expand to fracture the rock mass. Using the fracturing machine, they carried out various experiments on for a steel pipe, a granite block (80 x 40 x 70 cm) and completed numerical analysis using the Boundary Element Method or FEM. Both measured and calculated data coincide. Figure 10 shows the result of an experiment in which this machine fractured a leading pipe with internal diameter of 2 m filled with ultra-high-strength concrete. Aoi and Ashida [5] presented the result of various performance tests to confirm the drivability of hydraulic vibratory hammers, which consists of a body and a hydraulic power pack. Experiments with three types of hydraulic vibratory hammer and one electric vibratory hammer were carried out on clayey soil and on sand ground. An example of the relationship between the driving depth and time obtained for clayey ground is shown in Fig. 11. This diagram shows that the driving speed of a hammer increases as extra weight is added to it. The hammer combined with a water jet or with mounted extra weight shows remarkable drivability. The relationship between

FIG. 10. Conditionof resultingfractures(after Kadota et

al.

[7]).

P R O B L E M S B E T W E E N SOIL A N D C O N S T R U C T I O N M A C H I N E R Y

51

Time (min) 0

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FIG. 11. T h e result of performance test (after Aoi and Ashida [5]).

the rate of total dead-weight with regard to dynamic soil resistance and speed is shown in Fig. 12, which indicates that the greater the W/Fv, the faster the pile penetrates sand. The equation to estimate driving speed is also shown in Fig. 12. Fu [10] tried to establish a new mathematical model for the moment limiter of a crane and to improve the reliability of a moment limiter, as controlled by a microcomputer. An equation derived from measured data corresponds to the mathematical equation. The results, given by the mathematical model, are said to agree satisfactorily with the measured data. Gao and Zhu [11] tried to derive a new equation for the optimum space of the spaced link track through a theoretical use of Sokolovski's statics theory for a granular medium. They also attempted to compare this with the formula of Bekker [102] and Oida [103].

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O-otal dead-weight) / (Dynamic soil resistance) F~c. 12. The relationship between the rate of total dead weight with regard to dynamic soil resistance and driving speed (after Aoi and Ashida [5]).

52

H. FUJII

Acknowledgement--The author appreciates the kind advice of Professor A. G. Altschaeffl of Purdue University.

REFERENCES [1] T. TAMURAand T, SAKAI,Measurement of the degree of compaction by the impedance method. J. Terramechanics 29(1), 125-135 (1992). [2] G. J. HEFER, The influence of vibratory compaction on soil strength and trafficability. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1101-1112 (1990). [3] K. ISHIHARAand K. NAKAMURA,On the compaction property in the application of the Towed Edge Huge Vibration Plate Tamper. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1113-1122 (1990). [4] H. OHTA, T. MUTA, Y. KANEKO, M. OHTAKEand A. IIZUKA, Strength of compacted earth fill. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1123-1128 (1990). [5] A. Aoi and S. ASHIDA, Studies on drivability of SHP hydraulic vibratory hammer. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1171-1180 (1990). [6] M. GoTo, New method of soil improvement applied to strengthen high embankments on soft ground. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1129-1138 (1990). [7] S. KADOTA, T. NOMA and A. WAKU, Development of non-blasting method for rock mass using fluid pressure. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1161-1170 (1990). [8] M. GEORGIEFF, D. DANCHEV and S. STOICHEV, Investigation of the work process of a computer controlled shovel loader. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1139-1152 (1990). [9] T. MURO, Estimation of wear life of wheel loader tyre. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1191-1202 (1990). [10] D. Fu, Mathematical modeling of moment limiter in mobile cranes. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1181-1190 (1990). [11] X. GAO and J. Znu, A study on the theoretical pitch and optimum space of tracks of construction machinery. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 1153-1160 (1990). [12] A. W. JOHNSON and J. R. SALLBERG, Factors that influence field compaction of soils. Highway Research Board 272, 1-204 (1960). [13] R. R. PROCTOR, Fundamental principles of soil compaction. Engng News Record 111(9), 245-248 (1933). [14] R. R. PROCTOR, Description field and laboratory methods. Engng News Record 111(10), 286-289 (1933). [15] R. R. PROCTOR, Field and laboratory verification of soil suitability. Engng News Record 111(12), 348-351 (1933). [16] R. R. PROCTOR, New principles applied to actual dam building. Engng News Record 111(13), 372-376 (1933). [17] R. R. PROCTOR, The relationship between the foot pounds per cubic foot of compaction effort and the shear strength of compaction. Proc. 2rid Int. Conf. Soil Mech. Foundation Engng, Vol. 5. pp. 219-223 (1948). [18] R. R. PROCTOR, Relationship between foot pounds per cubic foot of compactive effort to soil density. Proc. 2nd Int. Conf. Soil Mech. Foundation Engng, Vol. 5, pp. 223-227 (1948). [19] R. R. PROCTOR, The relationship between the foot pounds per cubic foot of compactive effort expended in the laboratory compaction efforts to secure similar results with sheep foot rollers. Proc. 2nd Int. Conf. Soil Mech. Foundation Engng, Vol. 5, pp. 231-234 (1948). [20] S. T. JOHNSON and A. A. MAXWELL, Mechanical method subgrade compaction tests with heavy rollers. Proc. 2nd Int. Conf. Soil Mech. Foundation Engng, Vol. 5, pp. 216-219 (1948). [21] L. A. DRaOSE, A comparison of the physical properties of an alluvial silt compacted by field and laboratory methods. Proc. 2nd Int. Conf. Soil Mech. Foundation Engng, Vol. 5, pp. 219-223 (1948). [22] R. K. BERNHARD, Static and dynamic soil compaction. Proc. Highway Research Board, Vol. 31, pp. 563-592 (1952). [23]. G. KUNO and Y. AWANO, Field test on soil compaction with compaction equipment. Rep. Inst. Sci. Technol. of Tokyo Univ., Vol. 6, No. 6 (in Japanese), 379-393 (1952). [24] J. SASAKI,H. NEGISHI and T. KOSUGA, Study on compaction method (4) (in Japanese). Inst. Agric. TechnoL Rep. (2), 65-100 (1960). [25] K. SAWADA,Stress in situ during wheel travel (in Japanese). J. Japanese Soc. Soil Mech. Foundation Engng 12(10), 9-15 (1964). [26] D. J. D'APPOLONIA, R. V. WHITMAN and E. D. D'APPOLONIA, Sand compaction with vibratory rollers. Proc. Am. Soc. Civil Engng, Vol. 95, SM1 263-284 (1969). [27] H. FuJn and T. WATANABE,Stress generated by a pneumatic tyred roller during compaction--experimental studies on the compaction of fill-type dams (5) (in Japanese). Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng (42), 34-41 (1972). [28] H. Fwn and T. WATANABE,Stress generated by a vibratory roller during compaction--experimental

PROBLEMS BETWEEN SOIL AND CONSTRUCTION MACHINERY

[29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39]

[40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59]

53

studies on the compaction of fill-type dams (6) (in Japanese). Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng (42), 42-46 (1972). H. FuJn and T. WATANABE,Stress generated by a tamper during compaction--experimental studies on the compaction of ill-type dams (8) (in Japanese). Sci. Rep. Faculty of Agric., Okayama Univ. (41), 97-104 (1973). H. FuJll, Experimental studies on compaction of fill-type dam (in Japanese). Thesis for Doctorate of Kyoto University (1973). H. FuJn and T. WATANABE,Model of stress variation at a point in situ while compacted by a bulldozer (in Japanese). Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng (83), 44-55 (1979). H. FuJli, T. SAWADAand T. WATANABE,The stresses in situ while compacting by different types of compaction equipment. Proc. Int. Conf. Compaction, Vol. 1, pp. 41-46 (1980). H. FuJn, T. SAWADAand T. WATANABE,Stress in situ by various types of compaction equipment and their compaction effect. Proc. Int. Conf. Compaction, Vol. 3,265-268 (1981). H. FuJn, Characteristic of stress variation in situ due to bulldozer. Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng (99), 40-52 (1982). H. FuJii, T. SAWADAand T. WATANABE,Stress in situ generated by bulldozers. Proc. 8th Int. Conf. ISTVS, Cambridge, Vol. 1, pp. 259-276 (1984). I. YOSHIDA, Experimental study on vehicle travelling (in Japanese). J. Japanese Soc. agric. Much. 33(1), 15-18 (1971). B. B. BROMS and L. FORSSBLAD,Vibratory compaction of cohesionless soils. Proc. 7th Int. Conf. Soil Mech. Foundation Engng, SP, pp. 1-19 (1969). E. D. HONIGS, A. A. VALENTEand L. D. GRAVES, Compaction of sand by vibration alone. Highway Research Board 22, 1-9 (1957). R. K. BERNHARD,A study of soil wave propagation. Proc. Highway Research Board, Vol. 37, pp. 618-646 (1958). F. J. CONVERSE,Compaction of sand at resonant frequency. ASTM STP 15, 124-137 (1953). S. MURAYAMA,K. TANIMOTOand S. MATSUNO,Soil compaction with surface vibration (in Japanese). J. Japanese Soc. Civil Engng 40(11), 6-11 (1955). D. C. MOONHOUSEand G. L. BAKER, Sand densification by heavy vibratory compaction. Proc. Am. Soc. Civil Engng 95 (SM4), 985-994 (1969). W. A. LEWIS, Recent research into the compaction of soil by vibratory compaction equipment. Proc. 5th Int. Conf. Soil Mech. Foundation Engng, Vol. 2, pp. 261-268 (1961). R. N. YONO, P. BOONSINSUKand E. A. FATrAH, Prediction of tire performance on soft soils relative to carcass stiffness and contact area. Proc. 6th Int. Conf. ISTVS, Vienna, pp. 643-675 (1978). R. N. YONG and E. A. FATrAH, Analysis of soil compactability by rollers. Application of Plasticity and Generalized Stress-Strain in Geotechnical Engineering, pp. 308-332 (1982). R, N. YONG, Vehicle Traction Mechanics. Elsevier (translated to Japanese by M. K1TANO) (1989). E. A. FATrAH, R. N. YONG and K. S. NG, Compactability of soil under towed roller. Proc. 7th Int. Conf. 1STVS, Calgary, pp. 585-608 (1981), M. KITANO and M. TOKITA, Study on interaction between a rigid roller and soil (in Japanese). J. Japanese Terramechanics (5), 48-54 (1985). E. T. SELIG, Fundamentals of vibratory roller behavior. Proc. Int. Conf. Soil Mech. Foundation Engng, pp. 375-380 (1977). M. HAKUNO, Y. FUJISHIROand Y. YOKOYAMA,Dynamic pressure bulb (in Japanese). Proc. Japanese Soc. Civil Engng (24), pp. 109-110 (1969). H. FuJn and T. WATANABE,Several considerations on field compaction (in Japanese). Trans. 40 Japanese Soc. Civil Engng 3, 581-582 (1985). H. FuJII, K. SHIMADA,S. NISHIMURAand N. TAJIRI, Several considerations about the mechanism of field compaction. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 393-404 (1990). A. CASAOI~O~DEand W. L. SHANNON, Stress-deformation and strength characteristics of soil under dynamic loads. Proc. 2nd Int. Conf. Soil Mech. Foundation Engng, pp. 29-34 (1948). R. V. WHITMAN, The behavior of soils under transient loading. Proc. 4th Int. Conf. Soil Mech. Foundation Engng, Vol. 1, pp. 207-210 (1957). T. S. Yoo and E. T. SELlO, Dynamics of vibratory roller compaction. Am. Soc. Civil Engng GT.10, 1211-1231 (1979). A. FEKETE, Some effects of vehicle speed on soil compaction. Proc. 6th Int. Conf. ISTVS, Vienna, Vol. 3, pp. 1021-1033 (1978). R. A. Scoa-r and R. W. PEARCE, Soil compaction by impact. Geotechnique 25, 19-30 (1975). T. SuzuKi and B. YAMADA, Axial soil deformation behavior and its characteristics in ground compaction by impact (in Japanese). Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng 145, 9-18 (1990). S. HATA and K. TATEVAMA,Theoretical approach to impact soil compaction through plastic wave propagation. Proc. lOth Int. Conf. ISTVS, Kobe, pp. 404-414 (1990).

54

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[60] S. YAMAMOTO,Y. OMOTE and M. HAKUNO, Distinct element analysis for dynamic settlement of gravel rock ground (in Japanese). Trans. 25 Japan National Conference on Soil Mechanics and Foundation Engineering, 1811-1814 (1990). [61] J. W. HILF, Compacted fill. Foundation Engineering Handbook (edited by H. F. WINTERKORN),pp. 231-244. Van Nostrand Reinhold, New York (1975). [62] R. D. KREBS and R. D. WALKER,Highway Materials. McGraw-Hill, New York (1971). [63] H. FuJli, Z. WATANABI'2,T. KOSAKA, H. TAKEUCHI and T. YAMAMOTO, Comparison of various compaction methods in situ. Proc. 1st Asia-Pacific Conf. ISTVS, pp. 143-158 (1986). [64] H. FuJii and T. WATANABE,Decision of field compaction efforts by surface settlements--experimental studies on the compaction of fill-type dams (1) (in Japanese). Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng (41), 49-55 (1972). [65] I. GARCIA-BENGOCHEA,C. W. LOVELL and A. G., ALTSCHAEFFLE,Pore distribution and permeability of silty clays. Proc. Am. Soc. Civil Engrs J. GE 105,839-856 (1979). [66] E. T. SEL1G,Soil strain measurement using inductance soil method. ASTM STP 584, 141-158 (1975). [67] A. EGGESTAD,A new method for compaction control of sand. Geotechnique 24 (2), 141-153 (1974). [68] A. EGOESTAD, Experiences of compaction control in sand and gravel. Proc. Int. Conf. Compaction, Vol. 2, pp. 531-534 (1980). [69] N. MATSUMOTO, M. OGAWA and Y. HIRONAKA,Measurement of settlement by high sensitivity displacement sensor in field compaction test (in Japanese). Proc. 21 Japanese Nat. Conf. Soil Mech. Foundation Engng 1775-1776 (1986). [70] J. RE1CHERT, Various national specifications on control of compaction. Proc. Int. Conf. on Compaction, Vol. 3, 181-206 (1981). [71] T. R. GIDDINOS,A rapid method of controlling compaction by plate loading tests. Proc. Int. Conf. on Compaction, Vol. 2, pp. 547-552 (1980). [72] P. LUBgING, E. JANSE, J. F. JONKER, DE JAGER, Investigation on the variation of density, rigidity and bearing capacity measuring results on behalf of the acceptance control of sand subbases. Proc. Int. Conf. Compaction, Vol. 2, pp. 515-521 (1980). [73] V. ESCARIO, Correlations between plate bearing tests and deformations originated by a 10 t axle load for compaction control of earthworks. Proc. Int. Conf. Compaction, Vol. 2, pp. 535-540 (1980). [74] H. FuJii and T. WATANABE,Decision of field compaction efforts by penetration test--experimental studies on the compaction of fill-type dams (5) (in Japanese). Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng (41), 56-61 (1972). [75] D. M. HENDRON and L. L. HOLSH, Quality of control of earthwork construction using cohesive soils with highly variable properties. Proc. Int. Conf. Compaction, Vol. 2. pp 565-570 (1980). [76] A. G. ALTSCHAEFFLEand C. W. LOVELL, Improving embankment design and performance. Purdue University (1983). [77] S. HATA and K. TATEYAMA,Quality control in soil compaction by behaviors of exciter. Proc. 8th Int. Conf. ISTVS, Cambridge, Vol. 2, pp. 691-705 (1984). [78] R. FLoss, N. GRUBOR and J. OBERMAYER, A dynamical test method for continuous compaction control. Improvement of Ground, pp. 25-30 (1983). [79] L. FORSSBLAD, Compaction meter on vibratory roller for improved compaction control. Proc. Int. Conf. Compaction, Vol. 2, pp. 541-547 (1980). [80] L. FORSSBLAD,Roller-mounted compaction meters. Proc. lOth Int. Road Federation, pp. 1-8 (1984). [81] H. THURNER and A. SANDSTROM,A new device for instant compaction control. Proc. Int. Conf. Compaction, Vol. 2, pp. 611-614 (1980). [82] S. HANSBO and B. PRAMBORG, Compaction control. Proc. Int. Conf. Compaction, Vol. 2, pp. 559-564 (1980). [83] E. F. SCHWAB, O. PREOL and W. KmRES, Compaction control with the compactrometer. Improvement of Ground, pp. 73-82 (1983). [84] H. FuJll and M. MORIKUNI, Evaluation of compaction degree of soil using acceleration--study on evaluation of compaction effect in situ (1) (in Japanese). Trans. Japanese Soc. of Irrigation, Drainage and Reclamation Engng (141), 19-31 (1989). [85] H. Fu.nl, T. AZETU and T. YAMAMOTO,Several considerations of the evaluation of field compaction of rockfill material (in Japanese). Proc. Symp. Coarse-grained Materials, Japanese Soc. for Soil Mechanics and Foundation Engineering, pp. 87-92 (1990). [86] A. SmMAZU, K. MINAMI, K. NAKAXAand I. SH1MADA,Method of compaction control applying the acceleration of drum on vibratory roller (in Japanese). Rep. Ovil Engng 27-11, 27-32 (1985). [87] K. Mn~AMI, H. NAKATA,T. SAt,A1 and A. SHIMAZU,Non-destructive test method for soil compaction control (1) (in Japanese). Proc. 22 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 1653-1656 (1987). [88] H. NAKATA, A. Smr~AZU, T. SAr,AX and K. Mn~AMI, Non-destructive test method for soil compaction control (7)--application of resonant test (in Japanese). Proc. 23 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 2025-2026 (1988). [89] R. RUEOCER, Controle dynamique du compactage de couches en materiaux non lies. Proc. Int. Conf.

PROBLEMS BETWEEN SOIL AND CONSTRUCTION MACHINERY

55

Compaction, Vol. 2, pp. 597-604 (1980). [90] T. SAKAI and Y. IDEHARA, Non-destructive test method for soil compaction control (2)--measurement of mechanical compliance with an impedance head (in Japanese). Proc. 22 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 1657-1658 (1987). [91] T. TAMURAand T. SAKAI,Non-destructive test method for soil compaction control (8)--measurement of dynamic stiffness with impedance head (in Japanese). Proc. 23 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 2027-2028 (1988). [92] T. TAMURA and T. SAKAI, Development of new equipment for soil compaction control--measurement of dynamic stiffness of soil ground with impedance head (in Japanese). Proe. 24 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 1829-1830 (1989). [93] T. TAIVlURA,Y. KAWASE, Z. SAKAI and K. MINAMI, Non-destructive test method for soil compaction control (3)--measurement of dynamic stiffness with falling cone (in Japanese). Proc. 22 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 1659-1660 (1987). [94] M. TAKASU,T. FUJIKAWA,T, SATOU, T. SAKAI and K. MINAMI,Non-destructive test method for soil compaction control (5)--measurement of soil stiffness by seismic prospecting (in Japanese). Proc. 22 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 1663-1664 (1987). [95] M. TAKASU,T. FUJIKAWA,T, SATOU, T. SAKAI and K. MINAMI,Non-destructive test method for soil compaction control (4)--relation between permeative characteristics of electromagnetic wave and soil compaction (in Japanese). Proc. 22 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 1661-1662 (1987). [96] JSSMFE, Control of earth work and radio-active isotopes (in Japanese). Japanese Soc. for Soil Mechanics and Foundation Engineering (1974). [97] M. GoRsru, Continuous measurement of road layer density with radio-active method. Proc. Int. Conf. Compaction, Vol. 2, pp. 553-558 (1980). [98] T. PRZEDECm and M. SZVMSKI, Isotropic method for control of compaction of non-cohesive soils. Proc. Int. Conf. Compaction, Vol. 2, pp. 591-595 (1980). [99] JSSMFE, On the vertical density distribution in the compact layers of coarse-grained materials. Proc. Syrup. of Coarse-grained Materials Japanese Soc. for Soil Mechanics and Foundation Engineering, pp. 87-92 (1990). [100] M. TAKASU,T. FUJIKAWA,T. SATOU, T. SAKAI and K. MIrqAMl, Non-destructive test method for soil compaction control (10)--relation between permeative characteristics of electromagnetic wave and soil compaction (in Japanese). Proc. 23 Japanese Nat. Conf. Soil Mech. Foundation Engng, pp. 2031-2032 (1988). [101] T. MtJRO, Estimation of wear life of wheel loader tyre. J. Terramechanics 29(1), 137-147 (1992). [102] M. G. BEKKER, Off-the-road Locomotion. University of Michigan Press, Ann Arbor (1960). [103] A. On, A, Study on the efficiency analysis of running and drawbar pull of tractors (in Japanese). Thesis for Doctorate of Kyoto University (1975).