D runway at the Tokyo international airport (Haneda airport) consists of the land reclamation and pier sections. The design working life of the runway is given as 100 years. Steel pipe sheet-pile cellular seawall using high-strength pipe junction is applied to the connecting section between the land reclamation and pier sections. So as to achieve the long design working life, it is important for the design of the seawall to realize the accurate prediction of the long-term lateral displacement of the seawall due to the high embankment in the land reclamation section. In this paper, the authors conduct the soil/water coupled elasto-viscoplastic finite element analysis to evaluate the long-term lateral displacement of the cellular seawall. The constitutive model, proposed by Sekiguchi and Ohta (1977) with the modified cam clay type yield surface, is used in the analysis to improve the prediction accuracy of the deformation of soft clays.
Effective hydraulic conductivity keff should be applied when the groundwater flow is analyzed by using the continuum model for heterogeneous porous medium. Moreover, hydraulic conductivity calculated by the in-situ experiment is measured slightly higher than the actual value. Therefore, effective hydraulic conductivity keff should be calculated after the actual distribution of hydraulic conductivity is appropriately estimated from the results of in-situ experiments. In this study, the actual distribution of hydraulic conductivity is estimated by the inverse analysis using the stochastic finite element method. Validity was examined by a numeric experiment. In addition, an example of estimating the ke for sample data was presented.
It is important to consider the effect of the intermediate principal stress on 3D shear behavior of granular materials, although there are various factors. The objective is to investigate it macro- and micro-mechanically using dense specimen with spherical particles by Distinct Element Method (DEM). It was found that the relationship between the normalized plastic work and the equivalent plastic deviatoric strain is not strictly unique for different b values, and that the directivity of the contacts with relatively large contact force and the constraint condition due to b value cause the deviation of principal deviatoric strain from the linear relation obtained for isotropic and elastic material, and that numerical experimental results coincide with Lade and Duncan's failure criterion, and that there is a unique relationship among the coordination number, the plastic volume and the equivalent plastic deviatoric strain.
Ground anchors are important to do maintenance after construction. The maintenance of ground anchors is generally conducted to a part of total number of anchor on the slope. However, anchors are consisting of group on the slope, therefore it is necessary to evaluate a distribution of residual anchor load on the slope for an efficient maintenance. In this paper, we conducted many lift-off tests on cut slopes, and proposed a maintenance method of anchors slope that based on distribution characteristics of the residual anchor load.
The objective of this paper is to evaluate earthquake-induced residual displacement at a ground. I have developed K0-controled experiment device. This device achieves K0 condition during consolidation, undrained cyclic shear and reconsolidation process. The relation between liquefaction-induced residual displacement and duration and overconsolidation ratio OCR are studied by the method. As a result, volumetric strain εv and residual shear strain γres variation with different types of earthquake motions and OCR was examined. We suggested the residual deformation index which could evaluate both residual shear strain and residual volmetric strain. It was associated with accumulated strain γacm.
It is important for waste management and sound material-cycle society to clarify the change of the physico-chemical properties of reusable material. In this study, the influence of cation leaching on water retentivity of drinking water sludge was investigated. The column leaching test was executed using drinking water sludge to simulate rainwater percolation, and the water retentivity test of the degraded sludge was executed. As a result, the water retentivity of drinking water sludge decreased after cation leaching. The cation exchangeable capacity of drinking water sludge and its microscopic structure were almost stable during the leaching test. The results indicate a possibility that Al leaching decreases the hydrophilic part of flocculating agent which relates to water retention of drinking water sludge.
A simplified method for evaluating the liquefaction of sandy soil confined by a lattice-type deep mixing wall is proposed in this paper. The method calculates the accumulative excess pore water pressure from the initial shear strain using an equivalent shear-stiffness model by homogenization method. The method uses only parameters that are clear in their physical meaning, and can evaluate not only the effect of variations in the external forces, but also the physical properties of the ground. This paper first explains the proposed idea and then presents a specific calculation procedure using an actual site plan.
Shirasu which is defined as the non-welded part of pyroclastic flow deposits is widely distributed in the southern part of Kyushu Island. Shirasu is regarded as a soft ground when the mountain tunneling method is applied because its unconfined compression strength is only 20-100 kN/m2. Nevertheless, it is well known among the practical engineers that Shirasu tunnel is stable. In this paper the mechanical properties of Shirasu tunnel was analyzed, taking account of the geotechnical properties of Shirasu ground, where the laboratory and in-situ tests were carried out with the field measurement in tunnel. Furthermore the numerical experiment by FDM was also performed by using the proposed nonlinear mechanical model for Shirasu ground to compare the numerical results with those obtained from the field measurement.
The liquefaction countermeasure technical method, whereby the liquefaction strength is enhanced by making sand deposit in the state of unsaturation, is currently under study. The author et al have suggested a simple method of verifying the persistence of residual air using the undisturbed sample under ordinary temperature and sampling underground water; and have actually implemented the method in the adjacent ground with the foundation of viaduct pneumatic caisson where the leaked air during the construction was considered to have been trapped. We demonstrated the method of correcting the influence of the pressure of sampling specimen as well as of the dissolved air, and studied the precision of required degree of saturation. As the result, it has been shown that the residual air entrapped in the sand deposit is sustainable for as long time as about 28 years.
The number of abutments confined by fills constructed on expressways have increased to utilize materials generated on-site and reduce costs. An abutment confined by fill is an abutment constructed on an embankment-ground and supported by piles. In order to build abutments on embankment-grounds, the embankment-ground requires good ground resistance. But, up to now, there is no established method for its design and construction. Accordingly, it became necessary to establish a method. To do this, we have studied 107 cases of embankment-ground constructions on expressways. This report shows their deformation characteristics, settlement characteristics, and the impact of earthquakes on piles constructed in embankment-grounds, and describes how the standards for the design and construction management of embankment-grounds were established based on the findings.
The objective of this study is to find ways to maximize the design economy of the shinso foundation (Japanese style caisson type pile) on the rock slope through an evaluation of strength properties of the rock before and after plasticity. We investigate the influence of soil properties on the design result by carrying out experiments which give the soil properties before and after plasticity and by doing parametric studies on the soil properties. Experiment using small-scale shinso foundation is performed to verify the validity of result of examinations. Comparison between the experiment and the analytical result reveals the bearing capacity characteristics of the shinso foundation on the slope and gives new insights on the more economical design of the shinso foundation.
To estimate the consolidation settlement of saturated clay ground, it is important to take the creep settlement during the primary consolidation into account. There are a lot of unknown factors, however, which affect the creep settlement during the consolidation. In this paper, in order to clarify the effects of creep during the primary consolidation, the relationships between effective stress relaxation under the undrained condition and the creep settlement were investigated by using the separate-type consolidometer. In conclusion, it is clarified that there exists a nonlinear relationship between them and the effect of creep settlement during the primary consolidation was discussed.
A method is presented for assessing the amount of settlements at the surface of the unsaturated backfill, by using the relationships between shear stresses, shear strains and volumetric strains, obtained from stress-controlled torsional cyclic shear tests under drained conditions. The method is based on the cumulative damage theory in which shear stress time histories based on one-dimensional dynamic analyses of the ground are took into consideration. Backfill settlements due to the Niigata-ken Chuetsu-oki Earthquake in Japan (2007) are calculated by using the proposed method. The calculated amounts of the settlements were estimated to have good agreement with the observed data.
In order to reveal change in mechanical characteristics of soil due to difference of compaction condition, a series of laboratory tests on sandy silt which was used as embankment material are performed. In those tests, shear strength, shear modulus and coefficient of permeability are measured under the various compaction conditions. Firstly, it is shown that shear strength of the specimen prepared at the optimum water content is higher than these of drier and wetter condition at the lower confining pressure. On the other hand, it is found that vertical permeability and shear modulus of the specimens depend on the degree of compaction and water content at compaction. At the same compaction energy, the permeability and the shear modulus show the minimum and maximum values at the wetter situation. Those experimental facts are reflected to the change in the soil fabric of specimen due to the compaction. In order to reveal the correlations among the shear strength, shear modulus and permeability coefficient prepared at the various compaction conditions are graphically-illustrated. Those explain that (1) increase of the permeability coefficient makes the strength reduction, (2) the shear strength increase in almost directly proportion to the shear modulus of compacted specimen. In this study, it is attempted to express the patterns for fabrics of compacted soil. At the compaction under drier condition, the finer particles generally stand up and coarse particles lay horizontally. By contrast, under wetter condition, the finer particles lay horizontally and coarse particles almost stand up. Those may explain reasonably the effects of condition of compaction on the mechanical properties.
Conventionally, an inspection method to evaluate stability of railway retaining walls is basically visual inspection. This is because there is no quantitative inspection method. Therefore, a percussion test which is commonly applied to bridge substructures to check its stability was applied to the leaning retaining walls for investigation of their frequency characteristics. Subsequently, to indentify the relationships between the integrity and frequency characteristics of the retaining walls, a series of model tests was conducted. Consequently, a newly developed stability inspection and evaluation methods were presented, and successfully verified to apply to existing leaning retaining walls.
In the Tokyo International Airport (Haneda Airport), a new runway named "D-runway" was constructed from March 2007 to October 2010. Because some part of the D-runway is located in a river mouth, a hybrid structure consisted of piled pier and reclamation fill was adopted. In the reclamation section, not only the ground improvement technologies (SD, CPD and CDM) but also the new developed construction materials (pneumatic mixing cement treated soil and air-foam treated lightweight soil) were utilized. This technical report describes the outline of the execution, quality control, and maintenance plan of the D-runway structure, from a view point of geotechnical engineering.
Landslide or slope failure is a three-dimensional movement phenomenon, thus a three-dimensional treatment makes it easier to understand stability. The ΔB method (simplified three-dimensional slope stability analysis method) is based on the limit equilibrium method and equals to an approximate three-dimensional slope stability analysis that extends two-dimensional cross-section stability analysis results to assess stability. This analysis can be conducted using conventional spreadsheets or two-dimensional slope stability computational software. This paper describes the concept of the partial restraining force in-troduction method for designing construction countermeasures using the distribution of the restraining force found along survey lines, which is based on the distribution of survey line safety factors derived from the above-stated analysis. This paper also presents the transverse distributive method of restraining force used for planning ground stabilizing on the basis of the example analysis.