SOILS AND FOUNDATIONS
Print ISSN : 0385-1621
Volume 24, Issue 3
Displaying 1-13 of 13 articles from this issue
  • HIROYUKI WATANABE, SEISHIRO SATO, KYOKO MURAKAMI
    1984 Volume 24 Issue 3 Pages 1-14
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    The relation between the factor of safety obtained from dynamic response analyses on arbitrary potential sliding surface of a rockfill dam and the one obtained from conventional method such as slice method has been made clear by introducing a concept of equivalent instantaneous seismic coefficient.Throughout many numerical experiments of dynamic response analyses conducted on a typical rockfill dam section with sinusoidal ground motions of various kinds of accelerations and periods, a simple expression for the sliding permanent displacements has been obtained as a function of maximum equivalent instantaneous seismic coefficient and duration of sliding which is independent of the scale and location of sliding surface, the period of ground motion and the amplitude of ground acceleration. This formula has been applied to the simplified evaluation for the sliding permanent displacements in the cases with the ground motions of recorded accelerograms.Acceleration response spectra of many recorded accelerograms have been calculated and the ratio of each maximum value to peak ground acceleration has been plotted against corresponding predominant period. With this diagram the amplitude of equivalent sinusoidal ground acceleration has been specified as 0.5 to 0.6 of peak ground acceleration in conservative side.Combining above formula with the magnification factors of the equivalent instantaneous seismic coefficients in the potential sliding circles near crest, an expression for the relationship between the amplitude of above equivalent sinusoidal ground acceleration and the earthquake-induced sliding displacement at near crest has been derived. Giving certain amount of allowable permanent displacement, an earthquake-resistant design diagram for rockfill dams concerning with the equivalent sinusoidal ground acceleration has been proposed.
    Download PDF (1491K)
  • CHIKAYOSHI YATOMI, AKIRA NISHIHARA
    1984 Volume 24 Issue 3 Pages 15-26
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    Much attention has been paid to anisotropic behavior of soils, such as the inherent anisotropy and the stress induced anisotropy. Nevertheless, they often appear in the literature without any clear definitions. In the theory of finite deformations, the concept of isotropy is well established and is clearly distinguishable from the objectivity. However, in the infinitesimal theory, which is usually assumed in soil mechanics, they seem to be in confusion and, as a result, even simple anisotropy is not clearly defined. In this paper, we therefore first discuss the general principles of constitutive equations in finite theories and in infinitesimal theories to make a clear distinction between the objectivity and the isotropy. One of our most important results is that, if reference vectors or tensors are employed, in infinitesimal theories, the objectivity requires that anisotropic materials can be represented by isotropic functions. Using a reference tensor, we finally give a clear definition of the inherent anisotropy and the stress induced anisotropy. We then examine their difinitions employing a concrete example and show how the principles derived are useful, including the failure condition and the materials of differential type.
    Download PDF (1106K)
  • MASANOBU ODA, KENICHIRO SUZUKI, TAKURO MAESHIBU
    1984 Volume 24 Issue 3 Pages 27-40
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    Elastic compliances for cracked materials like rocks and rock masses are theoretically formulated in terms of the generalized fabric tensor which has been introduced as an index measure to express explicity crack geometry. By means of uniaxial compression tests and supersonic wave velocity tests on gypsum plaster samples with random cracks, the formulation is proved to give a good approximation for describing the elastic response of cracked materials. The conclusions are summarized as follows : The principal axes of the fabric tensor of second-rank exactly coincide with the symmetry axes of the elastic compliance tensor of fourth-rank. The so-called self-consistent method is very useful to estimate the overall elastic moduli by taking into account effect of the elastic interaction among cracks. Since the supersonic wave velocity is closely related to the character of the fabric tensor, it can be expected that the field measurement of wave velocity is useful to estimate fabric tensor of in situ rock masses.
    Download PDF (1448K)
  • TAKESHI SATO, KANO UESHITA
    1984 Volume 24 Issue 3 Pages 41-51
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    The authors had a chance to analyze in-situ pumping test data obtained by partially penetrating wells. But the application of the conventional type curve method showed that the calculated thickness of confined aquifer was much larger than the measured one. Then a more efficient and practical method for estimating the thickness and the hydraulic parameters was derived from the unsteady state solution for the drawdown of groundwater head around a partially penetrating well into a confined aquifer.The in-situ pumping test data and simulated results for the partially penetrating well were analyzed by means of this proposed method. From these analyses, it is shown that the calculated thickness and the hydraulic parameters had a good agreement with the measured ones.
    Download PDF (1032K)
  • YASUHIKO OKOCHI, FUMIO TATSUOKA
    1984 Volume 24 Issue 3 Pages 52-68
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    A series of K0-consolidation tests on reconstituted sand specimens was performed to evaluate the effects of several stress or strain factors on K0-values. A double-cell triaxial apparatus was used to investigate the effects of (1) unpreferable variation in the radial strain during K0-consolidation, (2) the different initial stress condition from which K0-consolidation is started, (3) pre-shearing in the triaxial compression or extension stress condition and (4) the different sample preparation methods. A double-cell torsional shear apparatus was also used to evaluate the effects of torsional pre-shearing on K0-values. It was found that in order to obtain reasonably accurate K0-values of sand samples, the variations in radial strain induced both before and during K0-consolidation should be limited to a rather small value. It was also found that the effects of torsional preshearing on the K0-values were rather small as far as these torsional shearings induce small values of radial strain.
    Download PDF (1746K)
  • SEIICHI MIURA, SHOSUKE TOKI
    1984 Volume 24 Issue 3 Pages 69-84
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    A series of static triaxial compression and extension tests and cyclic undrained triaxial tests on the undisturbed specimens obtained by the in-situ block sampling method were performed to assess the anisotropy in the static and cyclic deformation-strength characteristics of naturally deposited sands. Test results showed that anisotropic mechanical properties can be observed clearly not only in artificially deposited sands, but also in naturally deposited sands. It was recognized that mechanical anisotropy of natural cohesionless soils examined in the present study is characterized by the phenomena in which sand is more compressible and less extensible in the horizontal direction than in the vertical direction of the in-situ sand grounds and is attributed to the fabric anisotropy formed by the parallel alignments of sand particles induced during their depositing process. Moreover, it was also indicated that the anisotropic stress-strain-dilatancy properties and liquefaction characteristics of naturally deposited sands which contain the least amount of finer fractions could be simulated to a certain degree in a laboratory by adopting the sand sample preparation method such as pluviation of sand through air and MSP methods described in the previous paper (Miura and Toki, 1982).
    Download PDF (1911K)
  • KENJI ISHIHARA, AKIRA YAMAZAKI
    1984 Volume 24 Issue 3 Pages 85-100
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    To explore the nature of cyclic stress alteration in the seabed deposits of sand due to travelling waves, two-dimensional stress analysis was made for homogeneous elastic half-space subjected to a series of harmonic loads moving on its surface. The analysis indicated that changes in shear stress occur in such a way that, while its amplitude is maintained constant, the directions of the principal stresses rotate continuously. With a view to simulating such stress changes in the laboratory test, a series of cyclic triaxial torsion shear tests was conducted on loose specimens of sand. The test results indicated that the conventionally defined cyclic stress ratio is reduced by about 30% if the rotation of the principal stress directions is involved in the cyclic loading. The magnitude of wave-induced pressure at the seabed was determined on the basis of the linear theory of water wave propagation. This water pressure fluctuation was applied over the seabed, which is assumed to be an elastic half-space, to determine the cyclic stress ratio induced within the seabed deposit. The cyclic stress ratio thus determined is compared against the cyclic stress ratio causing liquefaction and cyclic mobility in which the continuous rotation of principal stress directions is taken into account. The procedures as above are integrated into a simple methodology to perform liquefaction analysis under wave loading conditions.
    Download PDF (1637K)
  • AKIO NAKASE, TAKESHI KAMEI, FUMIAKI TANAKA
    1984 Volume 24 Issue 3 Pages 101-106
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    In order to investigate the influence of the number of load steps on the strength characteristics of normally consolidated cohesive soils in K0-consolidated undrained ((CK0U)^^-) triaxial test, K0-consolidated undrained triaxial compression and extension tests are performed on two different samples.It was found the the cu/p values obtained by (CK0U)^^- triaxial tests tend to decrease with an increase in the number of load steps in K0 consolidation and the cu/p value of soil with low plasticity index is subjected more easily to the influence of multi-step loading. This is particularly significant for extension test.
    Download PDF (710K)
  • Yoshichika Nishida
    1984 Volume 24 Issue 3 Pages 127-138
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    Download PDF (1192K)
  • Minoru Matsuo, Takaharu Shogaki
    1984 Volume 24 Issue 3 Pages 139-150
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    Download PDF (1540K)
  • Taiji Katsumi
    1984 Volume 24 Issue 3 Pages 151-158
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    Download PDF (813K)
  • Masaki Tsushima
    1984 Volume 24 Issue 3 Pages 159-167
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    Download PDF (1158K)
  • Tomomitsu Yasue
    1984 Volume 24 Issue 3 Pages 168-176
    Published: September 15, 1984
    Released on J-STAGE: February 29, 2008
    JOURNAL FREE ACCESS
    Download PDF (1023K)
feedback
Top