The reinforced earth wall have come into wide use in Japan after the Great Hanshin Earthquake in particular. Various types of reinforcing members are applied in that reinforced earth walls, e.g. metal strips, geosynthetics, steel bars with a bearing plate, and so on. Some of them have been developed in Japan. The authors have newly developed a reinforcing member incorporating both bearing resistance and friction resistance. In the present paper, a series of the small-scale pull-out test of the reinforcing members consisting of a steel bar with friction plate and bearing plate are performed to confirm the effectiveness of the reinforcement. From the test results, as to the cross-sectional shape of the friction plate, the friction plate of long shape in depth direction performed large pull-out resistance compared with the plate of short shape of the same sectional area. Enough resistance of the friction plate was demonstrated by setting it apart from a bearing plate in order to cut off the influence of the bearing plate. Furthermore, in the beginning of the pull-out, a ratio of contribution of the friction resistance to the bearing resistance was 60 to 70%. The contribution ratio of the friction resistance decreased to 40 to 50 % in a final stage of pull-out.

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In order to improve stability of the existing embankment slope against rainfall and/or earthquake, we developed a reinforcing method using small-diameter bladed steel pipes. To examine the efficiency of the reinforcing method, an actual scale test embankment with reinforcement was built. The test embankment had remained intact even after heavy rain with continuous rainfall depth of 200mm from typhoons during the observation period. Pull-out tests of the reinforcing pipes confirms that sufficient resistance can be provided by the blades on the pipes. Observation of the reinforced and unreinforced slopes in the unloading experiment wherein the slope toe was excavated to destabilize the slope confirms the effectiveness of the reinforcement against shallow failure of the slope.

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A local soil called “Polishing soil, Migaki-suna” (hereafter called as Polishing sand) is found in Handa district, Tsu city of Mie Prefecture. As we could easily surmise after its name, the sand in old days was utilized as polishing powder, tooth/washing powder, etc. The engineering properties of Polishing sand were in detail examined in the laboratory, bearing in mind mitigating any disasters in the Polishing sand ground or making use of it as fill material. The sand is stiff enough in natural state. However, it turns out uniform and fine sand with greyish white color. The sand exhibits the engineering characteristics similar to those of Shirasu, despite that Shirasu and the sand is categorized as sand and clay, respectively. In spite that the sand contains fines more than 90 percent, it shows alike sand behavior, since most of fines refer to silty grains (i.e., nearly 80 %) and those grains are made of volcano-originated glass. The shear strength characteristics of the in-situ sand are c_cu≒100-200 kPa, φ_cu≧40-50°, whereas those of reconstituted sample are c_cu=10kPa, φ_cu=36° on average. Since the reconstituted sample is vulnerable against submergence, some improvement with cement is needed when the sand is used as fill material.

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The remediation and reuse of contaminated soil to utilize land in metropolitan areas more effectively has recently become an important issue in Japan. Currently, there are a variety of methods for remediating contaminated soil, and each differs in scope and in the type of contaminants that can be removed from the soil. In terms of environmental impact and economic efficiency, it is important to fully understand the parameters and characteristics of each remediation method in order to select the optimal method for the given circumstances. This study details a soil remediation system that we developed, demonstrating its characteristics and mechanisms through its use at an actual construction site with contaminated soil. We also examine the possibility of expanding the scope of application to include sites with multiple contaminants and heavy metal contamination.

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Authors proposed the simple method in the previous paper that determined the space of grid of the soil cement mixing walls used as a liquefaction countermeasure. In order to improve the reliability of the simple calculation method, the seismic response analysis was conducted with the parameter of the space of grid, the shear modulus of the improvement, and the improvement length. Based on the analysis, three functions that composed the expression were reviewed. The reviewed method can evaluate the maximum horizontal shear stress of the ground inside of grid based on the seismic response analysis.
This simple method applied for building foundations that experienced a real large earthquake. Results of the method compared with the analytical result and the field investigation after the earthquake. The F_l value calculated by this method was evaluated on the conservative side, and had adjusted to the field investigation result. Therefore, it is thought that the simple calculation method proposed in this study is effective for the preliminary setting of a space of grid on the soil cement mixing walls.

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A 2-dimensional advection-dispersion analysis was carried out to examine the infiltration path and area of de-icing agent into groundwater along an expressway which has been used more than 30 years in a hilly and mountainous area. The results were as follows: Analytic values approximately agreed with observed values. The de-icing agent infiltrated and moved about 300 m distance from the expressway to the river for 15 years, and the salinity of de-icing agent at the observation points rose gradually with decreasing its rising rate. If the spraying of de-icing agent was stopped, it was predicted that it took about 30 years for the water quality of groundwater at existing wells to return to the original values before spraying it. Furthermore, it was found, as an infiltration mechanisn of de-icing agent, the shattered zone with high permeability greatly affected the infiltration path and area of de-icing agent.

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Energy-based liquefaction evaluation method was previously proposed and applied to simple soil models and case histories to show its general usability for a variety of seismic motions. The key of the proposed method is to compare cumulative upward wave energy with energy capacity of each layer, though theoretical background in this respect was not fully addressed in the previous paper. In this supplement, seismic wave energy and associated dissipated energy in one-dimensionally upward propagating SH-wave are formulated and discussed how to compare with liquefaction energy capacity in a simplified procedure using associated cyclic loading soil test data in the laboratory. Some additional case study is accordingly conducted to confirm the applicability of the simplified procedure in this energy-based method.

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