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21.
Hiroyoshi Hirai 《Marine Georesources & Geotechnology》2013,31(4):452-466
ABSTRACTAn investigation is made to present analytical solutions provided by a three-dimensional displacement approach for analysis of bucket foundations subjected to vertical and lateral loads in cohesive soils. The nonlinear vertical and lateral stiffness coefficients along the skirt of the bucket foundation in nonhomogeneous soil are presented using three-dimensional solutions for vertical and lateral loads and taking into account the dependence of stiffness coefficients on the shear strain. The vertical, lateral, and rocking stiffness coefficients on the base of the skirt of a bucket foundation are obtained from the solutions of hollow rigid cylindrical punch acting on the surface of a soil. The ultimate vertical stress of a soil under the base of a bucket foundation subjected to vertical and moment loads is presented analytically by considering only compression and ignoring tension on the base. The vertical and lateral yields along the skirt and the compression and shear failures on the base are taken into account in analysis of ultimate load capacities. Envelopes of the combined ultimate horizontal and moment load capacities of a bucket foundation in clay are shown. Relationships between ultimate lateral and moment load capacities and the embedment ratio (skirt length to diameter) are presented. 相似文献
22.
Ayako Shinozaki Hiroyuki Kagi Hisako Hirai Hiroaki Ohfuji Taku Okada Satoshi Nakano Takehiko Yagi 《Physics and Chemistry of Minerals》2016,43(4):277-285
Stability and phase relations of coexisting enstatite and H2 fluid were investigated in the pressure and temperature regions of 3.1–13.9 GPa and 1500–2000 K using laser-heated diamond-anvil cells. XRD measurements showed decomposition of enstatite upon heating to form forsterite, periclase, and coesite/stishovite. In the recovered samples, SiO2 grains were found at the margin of the heating hot spot, suggesting that the SiO2 component dissolved in the H2 fluid during heating, then precipitated when its solubility decreased with decreasing temperature. Raman and infrared spectra of the coexisting fluid phase revealed that SiH4 and H2O molecules formed through the reaction between dissolved SiO2 and H2. In contrast, forsterite and periclase crystals were found within the hot spot, which were assumed to have replaced the initial orthoenstatite crystals without dissolution. Preferential dissolution of SiO2 components of enstatite in H2 fluid, as well as that observed in the forsterite H2 system and the quartz H2 system, implies that H2-rich fluid enhances Mg/Si fractionation between the fluid and solid phases of mantle minerals. 相似文献
23.
Understanding the exhumation process of deep-seated material within subduction zones is important in comprehending the tectonic evolution of active margins. The deformation and slip history of superficial nappe pile emplaced upon high-P/T type metamorphic rocks can reveal the intimate relationship between deformation and transitions in paleo-stress that most likely arose from changes in the direction of plate convergence and exhumation of the metamorphic terrane. The Kinshozan–Atokura nappe pile emplaced upon the high-P/T type Sanbagawa (= Sambagawa) metamorphic rocks is the remnant of a pre-existing terrane located between paired metamorphic terranes along the Median Tectonic Line (MTL) of central Japan. Intra- and inter-nappe structures record the state of paleo-stress during metamorphism and exhumation of the Sanbagawa terrane. The following tectonic evolution of the nappes is inferred from a combined structural analysis of the basal fault of the nappes and their internal structures. The relative slip direction along the hanging wall rotated clockwise by 180°, from S to N, in association with a series of major tectonic changes from MTL-normal contraction to MTL-parallel strike-slip and finally MTL-normal extension. This clockwise rotation of the slip direction can be attributed to changes in the plate-induced regional stress state and associated exhumation of the deep-seated Sanbagawa terrane from the Late Cretaceous (Coniacian) to the Middle Miocene. 相似文献
24.
Hiroyoshi Hirai 《Marine Georesources & Geotechnology》2018,36(7):805-817
An investigation was made to present analytical solutions of cyclic response to suction caisson subjected to inclined cyclic loadings in clay using a three-dimensional displacement approach. A model representing the relationship between vertical load and vertical displacement and that between lateral load and lateral displacement along the skirt of suction caisson subjected to cyclic loadings is proposed for overconsolidated clay. For the effect of vertical load on cyclic load capacity of suction caisson, using the Mindlin solution in the case of a vertical point load, the vertical stress of soil under the base of suction caisson is presented. For the stress state of soil beneath the base of suction caisson subjected to cyclic loading, the Mohr–Coulomb failure line and critical state line are presented and the relationship between total stress, effective mean principal stress, stress difference, and pore-pressure is elucidated. The comparison of results predicted by the present method for a suction caisson subjected to cyclic loadings in clay has shown good agreement with those obtained from field tests. Cyclic behavior of clay up to failure is made clear from the relationship between cyclic tensile load, vertical and lateral displacements, and rotation and that between depth, vertical, and lateral pressures. 相似文献
25.
A three‐dimensional displacement approach for analysis of laterally loaded piles in nonhomogeneous soil 
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下载免费PDF全文 Hiroyoshi Hirai 《国际地质力学数值与分析法杂志》2017,41(16):1605-1635
An analytical approach using the three‐dimensional displacement of a soil is investigated to provide analytical solutions of the horizontal response of a circular pile subjected to lateral loads in nonhomogeneous soil. The rocking stiffness coefficient of the pile shaft in homogeneous soil is derived from the analytical solution taking into account the three‐dimensional displacement represented in terms of scalar potentials in the elastic three‐dimensional analysis. The lateral stiffness coefficient of the pile shaft in nonhomogeneous soil is derived from the rocking stiffness coefficient taking into account the rocking rotation of a rigid pile shaft. The relationship between horizontal displacement, rotation, moment, and shear force of a pile subjected to horizontal loads in nonhomogeneous soil is obtainable in the form of the recurrence equation. The formulation of the lateral displacement and rotation of the pile base subjected to lateral loads in nonhomogeneous soils is presented by taking into account Mindlin's equation and the equivalent thickness for soil layers in the equivalent elastic method. There is little difference between lateral, rocking, and couple stiffness coefficients each obtained from both the two‐dimensional and three‐dimensional methods except for the case of Poisson's ratio near 0.5. The comparison of results calculated by the current method for a pile subjected to lateral loads in homogeneous and nonhomogeneous soils has shown good agreement with those obtained from analytical and numerical methods. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
26.
Shigeto Hirai Yohei Kojima Hiroaki Ohfuji Norimasa Nishiyama Tetsuo Irifune Stephan Klemme Geoffrey Bromiley J. Paul Attfield 《Physics and Chemistry of Minerals》2011,38(8):631-637
Raman spectroscopy and heat capacity measurements have been used to study the post-perovskite phase of CaIr0.5Pt0.5O3, recovered from synthesis at a pressure of 15 GPa. Laser heating CaIr0.5Pt0.5O3 to 1,900 K at 60 GPa produces a new perovskite phase which is not recoverable and reverts to the post-perovskite polymorph
between 20 and 9 GPa on decompression. This implies that Pt-rich CaIr1−xPtxO3 perovskites including the end member CaPtO3 cannot easily be recovered to ambient pressure from high P–T synthesis. We estimate an increase in the thermodynamic Grüneisen
parameter across the post-perovskite to perovskite transition of 34%, of similar magnitude to those for (Mg,Fe)SiO3 and MgGeO3, suggesting that CaIr0.5Pt0.5O3 is a promising analogue for experimental studies of the competition in energetics between perovskite and post-perovskite
phases of magnesium silicates in Earth’s lowermost mantle. Low-temperature heat capacity measurements show that CaIrO3 has a significant Sommerfeld coefficient of 11.7 mJ/mol K2 and an entropy change of only 1.1% of Rln2 at the 108 K Curie transition, consistent with the near-itinerant electron magnetism. Heat capacity results for post-perovskite
CaIr0.5Rh0.5O3 are also reported. 相似文献
27.
In analyses of compositional data, it is important to select a suitable unchanging component as a reference to detect the
behavior of a single variable in isolation. This paper introduces two tests for detecting the unchanging component, based
on a new approach that utilizes the coefficient of variation of component ratios. That is, the coefficient of variation of
a compositional ratio is subject to change when the unchanging component is switched between the denominator and numerator,
and the coefficient of variation tends to be small when the unchanging component occurs as the denominator against any arbitrary
components (Test 1). In addition, the ratio of the component pair that gives the lowest coefficient of variation is most likely
to represent the two unchanging components (Test 2). However, Tests 1 and 2 are not necessary and sufficient conditions for
uniquely finding the unchanging component. To verify the effectiveness of the tests, 500 artificial datasets were analyzed
and the results suggest that the tests are able to identify the unchanging component, although Test 1 underperforms when the
dataset includes a component with skewness greater than 0.5, and Test 2 fails when the dataset includes components with a
correlation coefficient greater than 0.75. These defects can be overcome by interpreting the two test results in a complementary
manner. The proposed tests provide powerful yet simple criteria for identifying the unchanging component in compositional
data; however, the reliability of this approach needs to be assessed in further studies. 相似文献
28.
Hiroyoshi Hirai 《国际地质力学数值与分析法杂志》2008,32(5):523-557
The investigation of equivalent elastic method is made to predict settlements and stresses of multi‐layered grounds and improved grounds. Analytical models to represent the heterogeneous elastic properties of layers in vertical and horizontal directions for multi‐layered grounds and improved grounds are proposed in taking into account the equivalent elastic modulus and the equivalent thickness. By introducing the equivalent thickness derived from Terzaghi's formula of the vertical stress, the equivalent elastic method of using the equivalent elastic modulus and the equivalent thickness is applied to the formulations concerning immediate settlements and vertical stresses in multi‐layered grounds and improved grounds. Comparison is performed between rigorous solutions and simulations for immediate settlements and vertical stresses in multi‐layered grounds and improved grounds. It is found that the proposed method is able to describe properly the characteristics of distributions for settlements and vertical stresses in multi‐layered grounds and improved grounds. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
29.
Hiroyasu Ando Takeshi Noguchi Masao Nakagiri Akihiko Miyashita Yasumasa Yamashita Kyoji Nariai Hiroyoshi Tanabe 《Astrophysics and Space Science》1989,160(1-2):183-189
Two steps have been taken to decide at what place and altitude to set up the JNLT on Mauna Kea. First, the wind tunnel experiment has been made in collaboration with the Institute of Meteorology using the two models of summit area with the reduced scales of 1/1000 and 1/5000. This study tells us that the north-west cone is suitable for JNLT. Secondly, we have done the measurement of the microthermal activities in this area with a 30 m tower, which was continued for about 4 months in collaboration with the University of Hawaii. This experiment has given the mean vertical profile ofC
T
2
over 4 months and its scale height in the boundayr layer on our site. By use of these measurements, the contribution of the boundary layer to seeing is estimated. The behaviour ofC
T
2
under strong winds can be explained very well by topographic effects, which is in fairly good agreement with the results of our wind tunnel experiment.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988. 相似文献
30.
A nonlinear numerical model has been formulated to study the propagation of a monochromatic surface wave. The model is formulated through the vertical integration of the continuity equation and the equations of motion. This model is investigated for wave propagation, velocity distribution, energy propagation and varying Courant, Friedrichs and Lewy's (CFL) condition. The applicability of this model for both shallow- and deep-water wave is also examined. The results and analyses are shown in details. The results obtained from the model are compared with the Stokes third-order wave theory and with the relevant experimental data. 相似文献