It is widely recognized that liquefaction behavior is more closely correlated to dissipated energy than to applied stress, and hence Energy-Based Method (EBM) for liquefaction evaluation seems promising though Stress-Based Method (SBM) is exclusively used worldwide.　With this background, a research committee on EBM for liquefaction was held in the Japanese Geotechnical Society probably as a first endeavor in the world.　In this article, as the first paper in a special volume edited by the committee, a perspective on energy-based liquefaction interpretations is summarized based on the committee report together with a personal view of the author.　Among the major findings, test results on various intact soils sampled in situ demonstrate that cumulative dissipated energy can uniquely determine pore-pressure buildup and induced strain regardless of cyclic loading histories, and correlate with CRR in SBM uniquely again irrespective of soil properties.　Liquefaction evaluations are implemented for a hypothetical uniform sand layer as well as two case history soil layers by employing three different EBMs available in Japan wherein the cumulative dissipated energy is compared with earthquake wave energy at each soil layer.　The comparative study reveals in general that the EBM can predict liquefaction behavior without worrying about the variability of earthquake waves unlike the SBM, though there still remain differences in the evaluations among the three EBMs to be studied further.　Considering the great advantage of EBM over SBM, it is strongly recommended to be employed in engineering practice.

Saturated and unsaturated shearing behavior on sand, Shirasu, which is volcanic ash sand with pumice, and improved Shirasu (cement, chemical grouted and well compacted Shirasu) were investigated to valuate earthquake proof performance by cyclic triaxial test. Referencing that cyclic mobility, cumulated dissipated energy was calculated and compared with each other. Stress history, drainage conditions and degree of saturation influenced the dissipated energy. Improved soils became tough, reduced excess pore water pressure by positive dilatancy, and required more dissipated energy to reach 2.5% of single amplitude strain. Relation between liquefaction strength and dissipated energy could be approximately classified. Generally dissipated energy could be verified the soil performance during cyclic loading.

Development of energy-based method for liquefaction potential evaluations for practical use is undertaken in recent years. To find uniqueness between liquefaction behavior and the cumulative dissipated energy during the liquefaction process is important to establish the energy-based method. In this study, correlations between the cumulative dissipated energy and cyclic resistance ratio (CRR) in the stress-based method (F_L-method) obtained from a series of undrained cyclic triaxial tests on various intact samples from in situ were investigated. As the result, the dissipated energy is found to be almost uniquely correlated to CRR by correcting the energy, though the energy is apparently dependent on cyclic stress ratio in cyclic triaxial tests, because axial strain tends to accumulate on extension side. The obtained correlation can be applied to the energy-based liquefaction potential evaluation irrespective of the density, grain-size, consistency and the aging effect of soils.

This paper describes applicability of the energy based assessment method for soil liquefaction on seismic design of railway bridge piers. In the first place to begin with, a design model of a bridge pier was made, of which bearing capacities of foundation ground were decreased in consideration of soil liquefaction based on a relationships between degradation of soil stiffness and cumulative dissipation energy inputted to the liquefiable layer obtained. According to the result of an energy based assessment, three types of different inertia force determined were applied to the design model, and seismic responses of the bridge pier were calculated. These results obtained were compared with the result calculated according to the stress based assessment for soil liquefaction used in the current design method, which was able to give reasonable response of bridge piers damaged due to soil liquefaction in the past large earthquakes. As a results, it is confirmed that almost the same seismic responses are obtained, if the inertia force could be appropriately determined by the energy based method. This result clearly shows that the energy based assessment for soil liquefaction can be used for seismic design of railway viaducts in consideration of soil liquefaction. Finally, future necessary work items are summarized for developing more rational seismic design with energy based assessment for soil liquefaction.

The authors applied the idea of "Structural calculation of superstructure by seismic design based on energy balance method" to the ground and developed a liquefaction evaluation method. The basic idea of this proposed method is as follows, 1) Input energy of whole ground is calculated by energy spectrum, 2) Input energy is distributed to each layer as accumulate plastic strain energy, 3) degree of liquefaction damage is evaluated from the relationship between accumulate plastic strain energy and volumetric strain of each layer. In this paper, case study analysis were conducted with stress method and energy balance method under the same condition for virtual grounds, and the settlement amount was compared. The correction factor was required for an appropriated evaluation in the stress method while energy method requires no correction factor. The energy spectrum can be a good indicator of magnitude of seismic motion, if the intensity of seismic motion is defined by the magnitude of settlement caused by liquefaction. As a result, it was found that there was no significant difference in the evaluation of the settlement amount between the stress method and the energy method within the scope of these cases in this study.

In the Great East Japan Earthquake, the reclaimed land in Tokyo bay was damaged by liquefaction. In this study, a detailed ground investigation is conducted to clarify the damage mechanism by subsidence and inclination of detached houses due to liquefaction in Irifune 4—chome, Urayasu city, which suffered major damage after the earthquake disaster. The investigation included conducting questionnaire surveys on liquefaction damage, determining the N-value by using a standard penetration test, PS logging, groundwater level measurements, and laboratory tests for undisturbed samples that were collected continuously. This study describes; 1) the depth distribution of the liquefaction strength ratio obtained from continuously collected undisturbed samples, 2) the characteristics of each depth, and 3) the energy characteristics of each specimen. The characteristics of each method were then evaluated by comparing various liquefaction predictions (i.e., effective stress, stress based method (F_L method), energy method). In the results of liquefaction prediction, the rise process of excess pore water pressure by the effective stress analysis was almost entirely consistent with the eyewitness testimony of the in habitants. A difference in the evaluation result between F_L method and energy method was noted; in the F_L method, the F_L value decreases with depth, whereas in the energy method, it tends to liquefy easily with shallower depths.

For Energy-based liquefaction evaluation method, it is necessary to estimate the amount of seismic wave energy supplied to a target layer. In this paper, the seismic wave energy is calculated based on the strong motions recorded at the KiK-net stations near the seismic fault of the 2016 Kumamoto earthquake (M 7.3). From the result, the upward energy at the ground surface was found to be much smaller than that at base layer in most of the sites. The upward energy at a base layer tends to increase with decreasing equivalent hypocenter distance. Furthermore, the upward energies at base layers are not so much different from the theoretical values based on magnitude and equivalent hypocenter distance. From the results of classification into four directions based on fault mechanism, it became clear that the relationship between the upward energy and the equivalent hypocenter distance is different depending on the classification. Based on the comparison of liquefied area with non-liquefied area, it could be deduced that there exists a threshold seismic wave energy above which liquefaction occurs.

The strength of soil depends on the degree of compaction. Therefore, it is essential to investigate the degree of compaction of soil structure to evaluate its soundness. Compaction test has been widely used to investigate degree of compaction of the present embankment and compaction characteristics of ground material. This study aims to verify the applicability of the new compaction test method using a small size compaction test apparatus. In this paper, a series of small compaction tests using 5 cm diameter mold and 1.5kg rammer was performed to examine the effect of the maximum grain size and its content of soil samples on the compaction properties in the small mold. As a result, maximum grain size of soil sample within 9.5mm, compaction curves obtained from 5cm mold are approximately matched with compaction curves of 10cm mold. It was found that the allowable maximum grain size in 5 cm diameter mold is 9.5 mm. In addition, applicability of existing equation for estimating the compacted density of granular soils with oversize particles were evaluated.

The applicability of the dynamic load test and the calculation formula of dynamic bearing capacity was examined in detail compared with the results of the static axial compressive loading test only for the small diameter steel pipe pile constructed by rotary penetration. In this dynamic load test set so that the impact energy does not exceed the buckling stress of the small diameter steel pipe pile, the characteristics such as the yield and elastic return of the ground in the static axial compressive loading test were largely reproduced, and the upper limit of the estimated ultimate bearing capacity generally satisfied the target for this pile. The quantities of penetration and rebound in the dynamic load test were affected by the ground strength of the tip and the peripheral of the pile, the product of the impact energy and the penetration quantity showed a relation inversely proportional to the ultimate bearing capacity, and the product of the impact energy and rebound quantity showed a direct relationship with the ultimate bearing capacity. These were most consistent with the Hiley formula induction process. In addition, a high correlation was obtained between the dynamic ultimate bearing capacity by Hiley formula and the static ultimate bearing capacity by the static axial compression loading test. Therefore the applicability of Hiley formula and also effectiveness to the cases remaining high of the design length or the pre-drilling were confirmed.

The analytical results of simple batch leaching test and bulk concentration test under the Soil Contamination Countermeasures Act were compiled for naturally derived toxic elements in the alluvial marine clay layer (Ma13) beneath western Osaka Plain, Japan. Leaching concentrations of Pb, F, and B were almost within 3-4 times of upper limit of Japanese regulations, while 50% of As concentration data were more than 3 times higher than the regulation value. Bulk concentrations of Pb, As, F and B suggested that these elements were derived from natural resources. These objective and quantitative data set should be utilized for adequately reusing excavated soils and to achieve sustainable soil managements.

The mass of internal soil erosion adjacent to a geosynthetic drainage material due to precipitation and percolation was evaluated. Down-flow precipitation/percolation tests using a column were conducted on sandy soils under several precipitation intensities. The experimental results showed that there are two patterns which can be differentiated in terms of the masses of soil losses; Entire soil erosion and Locally soil erosion. Entire soil erosion occurred when sufficient precipitation/percolation intensity for the hydraulic conductivity of soil was continuously given, and is attributed to the seepage failure which occurred when the wetting-front reached the bottom of the column specimen and the condition for all the depth of the specimen reached saturation. In contrast, only preferential flow occurred either with insufficient precipitation/percolation intensity or with a limited period of precipitation with sufficient intensity resulting in Locally soil erosion. The formation of the eroded portions depends on the falling droplets. A theoretical method to estimate the magnitude of erosion is proposed based on the balance of weight of the droplet and the capillary force.

The 2011 off the Pacific coast of Tohoku Earthquake has caused significant liquefaction damage to residences that led us to recognize the importance of damage prediction and countermeasure evaluation for spread foundation structures. To estimate residual settlement and inclination of the structures properly, influence of shapes, neighboring positions and eccentric loading need to be considered; accordingly, numerical approach is suitable. We, then introduced the methodology of ALID, that has been widely used for two-dimensional analysis, to the three-dimensional analysis code. In this paper, we firstly explain the detail of the three-dimensional analytical method, then verified the applicability of the method through validation analyses on centrifuge model tests and post-analytical assessments on field investigation results obtained after the 2011 Earthquake in Urayasu-city. Finally, we conducted numerical experiments focusing on residual settlements and inclinations under four neighboring houses. By examining results of the numerical experiments from viewpoint of influence of neighboring positions and ground water levels, we provided expertise that may contribute to estimate residual settlement and inclination of relative low-rise structures in a future earthquake.

This paper presents experimental results of an unconstrained flow of dry sand down an inclined board at small scale, followed at the toe by a horizontal plane on which the sand spreads. The runout length increases with the increase in the volume of the falling sand and the slope angle. In order to identify these characteristics, mass point movement down an inclined board is introduced. If the position of the mass at start is given, it is possible to determine velocity and position of the point at any given time by means of the relationship of the energy loss, however, the mass point modeling, in which the mass point slides down the inclined board and reaches the horizontal plane, does not fully represent the runout length increase with the increase in the slope angle. To get better identification, we improve the mass-point modeling to explain climb-over and collision of particles, which may occur in the sand sliding down the slope.

This study evaluated the mechanical property of two types of rocks, tuff and lapilli tuff, by using in-situ triaxial compression test, which had been developed by previous researches. The stress-strain relationship including the peak shear strength and residual strength were obtained from the tests. The test results were compared with the test results of in-situ rock test (rock shear test and plate loading test). As a result, the peak shear strength and Young’s modulus obtained from different test methods were approximately equal. Therefore, the validity of the test results obtained from in-situ rock tests was verified from the in-situ triaxial compression test.

In order to propose an appropriate water sealing method at a disposal with heavy metal-containing excavated rocks prediction of the short-term and long-term elution phenomena is important. For that purpose, it is meaningful that advection / diffusion simulation by modeling the physical and chemical behavior of heavy metals through numerical analysis. So far, it is common to set the maximum elution amount from the analysis result of the sample before embankment, and it is rare to grasp the total elution behavior in the real embankment site. Regarding the dissolution characteristics, the average elution volume inside the embankment was 20% more than the original ground and the standard deviation was about half. In-site unsaturated permeability test, it was found that the saturated hydraulic conductivity differs depending on the measurement point and the test conditions, but the unsaturated permeability indicated the similar characteristic that change distinctly at the tip of the penetrating surface in the various test conditions.

Conventional commercial soil moisture sensors measure only in the vicinity of the sensor prongs, thus, provide a values of a “point”. This study, using multi-modal microchip sensors (impedance, phase and temperature), aims to establish a tomographic method to elaborate the point data for estimating the two-dimensional distribution of soil moisture. Infiltration and drainage were simulated using a soil tank in the laboratory to evaluate performance of a vertical gravel drain in a highway embankment. The water flow in the soil tank was monitored by the new microchip sensors and commercially available capacitance-based soil moisture sensors. The results showed that the point values and those between the sensors partly agreed with the point and areal average values from the capacitance sensors. The rest of the results, however, showed a significant discrepancy between the two sensor types. It indicated a need for a further close examination of presence and effects of heterogeneity in the soil tank, as well as the differences in sensors’ measurement characteristics.