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1.
A new technique is presented with which to investigate slope stability during strong earthquake motion. This technique is based on a non-linear finite element method that uses a joint element to express non-linear behaviour and the progressive failure of a slope. Joint elements are arranged at every interface between soil elements. Accordingly, each soil element is allowed to move in directions parallel, perpendicular and rotational to neighbouring elements; consequently, they express the sliding and separation at any interface between the soil elements. The method was used to investigate the stability of an existing slope during strong earthquake motions. Preliminary static analyses were made, and their results were compared with results obtained with Janbu's method in order to check the validity of our proposed method. The dynamic analyses also took into account the material non-linearity of the soil. The process of progressive failure was examined for a slope whose material constants are known. The influence of input excitations on slope stability is discussed in detail. The method also has been used to assess the effectiveness of a countermeasure used to prevent slope failure. 相似文献
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This paper presents an effective analysis procedure for the dynamic soil-structure interaction problem considering not only the sliding and separation phenomena but also the non-linear behaviour of soil by the finite element method. Soil is assumed to be an elasto-plastic material and the contact surface between the soil and structure is modelled by the joint element. The load transfer method is adopted to carry out dynamic non-linear response analysis. The method is applied to the response analysis of a nuclear reactor building resting on the ground surface. The effects of non-linear behaviour of soil on the safety against sliding of the structure are examined. The numerical computations reveal the following results: that the non-linear behaviour of soil reduces the response of the system and the magnitude of sliding of the structure, and that the safety against sliding obtained by the proposed method is higher than the safety obtained by classical methods. This implies the possibility of a more rational and economical design of large structures; it can be said that the proposed method provides useful information for the stability analysis of important and large structures. 相似文献
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Kenzo Toki Tadanobu Sato Junji Kiyono Nozar Kishi Garmroudi Susumu Emi Masaaki Yoshikawa 《地震工程与结构动力学》1991,20(10):895-909
Non-linear seismic soil-pile interaction was studied with a hybrid procedure that used a pseudo-dynamic testing (PDT) method modified to account for frequency dependence and developed for foundation-soil systems. The numerical scheme used in the conventional PDT was improved by the introduction of a time-dependent pseudo-forcing function derived from the frequency-dependent dynamic characteristics of the system by Hilbert transformation in the frequency domain. Single, 2-, 3- and 9-pile group foundation models were used, their mechanical characteristics later being determined from static and forced vibration dynamic tests. Amplitude scaling was used for three recorded accelerograms. Data recorded during an earthquake at the site of the experiments revealed that the proposed methodology predicts well seismic nonlinear interaction and accounts for frequency dependence and non-linearity in the time domain. 相似文献
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Kenzo Toki Tadanobu Sato Junji Kiyono Nozar Kishi Garmroudi Susumu Emi Masaaki Yoshikawa 《地震工程与结构动力学》1990,19(5):709-723
Non-linear seismic soil-structure interaction is studied through a hybrid procedure using the pseudo-dynamic testing (PDT) method which is modified to take into account frequency dependence and developed for foundation-soil systems. The numerical scheme used in conventional PDT is improved by introduction of a time-dependent pseudo-forcing function which is derived from frequency-dependent dynamic characteristics of the system by means of Hilbert transformation in the frequency domain. Surface, shallow and caisson foundation models that differed in size and depth of embedment were used. The mechanical characteristics of the systems were determined from static and forced vibration dynamic tests. An amplitude scaling technique was used for three recorded accelerograms. 相似文献
5.
Development of a New Method of Extraction of Interstitial Water from Low‐Porosity Consolidated Sediments Recovered During Super‐Deep Drilling Projects 
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下载免费PDF全文 Tomohiro Toki Harue Masuda Harunur Rashid Sebastian Hammerschmidt Ryuichi Shinjo 《Geostandards and Geoanalytical Research》2016,40(2):291-300
During the Integrated Ocean Drilling Program (IODP) Expedition 338, several methods were tested for the extraction of interstitial water in consolidated, low‐porosity deep‐sea sediments from Site C0002 in the Kumano Basin. On the basis of those tests, we propose a modified ground rock interstitial normative determination (GRIND) method of extraction of interstitial water. In separate runs of the new method, sediment samples were ground in a ball mill with either ultrapure water or a solution of HNO3. The interstitial water was then extracted with a conventional squeezer. Sufficient solution was extracted by this method to analyse most major and a few minor components of interstitial water that were comparable to those previously reported for samples extracted by the conventional squeezing method. The new method requires much smaller amounts of sediment than that of the conventional method and will be useful for analysis of samples recovered during super‐deep drilling programmes. 相似文献
6.
Abstract We collected free-gas and in situ fluid samples up to a depth of 200.6 m from the Sagara oil field, central Japan (34°44'N, 138°15'E), during the Sagara Drilling Program (SDP) and measured the concentrations and stable carbon isotopic compositions of CH4 and C2 H6 in the samples. A combination of the CH4 /C2 H6 ratios with the carbon isotope ratios of methane indicates that the hydrocarbon gases are predominantly of thermogenic origin at all depths. The isotope signature of hydrocarbon gases of δ13 < δ13 suggests that these gases in the Sagara oil field are not generated by polymerization, but by the decomposition of organic materials. 相似文献
7.
Assessment of the vertical distribution on seismic ground motion 总被引：1，自引：0，他引：1
It is very important for the facilities such as nuclear power plants to infer seismic force loading on the earthquake stability assessment of the building foundation and the surrounding slope. The purpose of this paper was to propose a method to evaluate underground seismic coefficients, taking into account dynamic response along the depth in horizontally multi-layered ground. The dynamic property of the seismic coefficient was analyzed on the basis of earthquake records observed at hard and soft rock sites mostly found in Tertiary deposits and sedimentary ground sites of the Pleistocene and Holocene epoch. The evaluation methods of a vertical distribution on underground seismic coefficients were proposed for a few calculation methods on the classified layered ground. Extended evaluation for underground seismic coefficients was confirmed with respect to some multi-layered ground during strong motion. 相似文献
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We collected sediment samples and pore water samples from the surface sediment on the Daini Atsumi Knoll, and analyzed the sediments for CH4, C2H6, and δ13CCH4, and the pore fluids for CH4, C2H6, δ13CCH4, Cl−, SO42−, δ18OH2O, and δDH2O, respectively. A comparison of the measured concentration and isotopic composition of methane in pore water samples with those in sediment samples revealed that methane was present in the sediment samples at a higher concentration and was isotopically heavier than those in the pore water samples. It suggests that the effect of the release of a sorbed gas bound to organic particles when heated prior to analysis of hydrocarbons was larger than that of the degassing process. A large amount of a sorbed gas would be a significant source of natural gas. Two striking features are the chemical and isotopic composition of the pore water samples taken from the different sites around the Daini Atsumi Knoll. In the KL09, KL10, and KP07 samples, Cl− concentrations in the pore water samples showed depletion to a minimum of 460 mmol/kg, correspond to 17% dilution of seawater, however the latter was not enriched in CH4. The isotopic compositions of pore water samples suggested the low-Cl− fluids in the pore water were not derived from dissociation of methane hydrate, but were derived from input of meteoric water. In contrast, in the KP05 samples from the north flank of the Daini Atsumi Knoll, pore water were characterized by CH4 enrichment more than 370 μmol/kg, but not depleted in Cl− concentrations. The observed methane concentration in the KP05 samples is not sufficient for methane hydrate to form in situ, indicating that the existence of methane hydrate in the surface sediment is negligible, as supported by Cl− concentration. Based on the stable carbon isotope ratio of methane in the pore fluid from the KP05 site (δ13CCH4 < − 50‰PDB), methane is thought to be of microbial origin. The pore waters in the surface sediments in the north flank of the Daini Atsumi Knoll were not directly influenced by upward fluid bearing methane of thermogenic origin from a deeper part of the sedimentary layer. However, extremely high methane concentration in the north flank site as compared with the concentration of pore water taken from the normal seafloor suggests that the north flank site is not the normal seafloor. We hypothesize that upward migration of chemically-reduced fluids from a deeper zone of the sedimentary layer reduces chemically-oxidized solutes in the surface sediment. As a consequence methane production replaced sulfate reduction as the microbial metabolism in the reduced environment of the surface sediment. 相似文献
10.
Previous achievements using the dynamic non-linear analysis of an interaction system are reviewed briefly, after which a three dimensional (3D) model of the stress redistribution of soil based on the Mohr–Coulomb failure law is presented to evaluate the unbalanced tensor at every iteration in the load transfer method. A 3D, full non-linear analysis was used to examine the validity and accuracy of results obtained by 2D analysis by combining the model of redistributed stresses proposed here with the joint element model. Based on the numerical solution reported here, we concluded that both the 3D and 2D models of stress redistribution work well and reflect the yielding pattern of soil during excitation, but the former is more realistic. The failure area in the structural zone obtained by 3D analysis is slightly larger but similar to that obtained by 2D analysis. The ratio of maximum strain to yield strain and non-linear time ratio, βs, for the soil elements in the structural zone are also a little larger. In contrast, the maximum separation values for the joint elements are much smaller and the separation pattern for the x-side wall interface is the reverse of that found by 2D analysis. These values, however, affect only responses in the short period range and the regions close to the interface. In general, the tendencies shown by 2D analysis for the effects of non-linear behaviour on structural responses are confirmed for the parameters investigated. 相似文献