Yoshihisa Miyata

National Defense Academy of Japan | NDAJ · Department of Civil and Environmental Engineering

The paper demonstrates load and resistance factor design (LRFD) calibration for tensile strength, connection strength, pull-out, and soil failure internal stability limit states for polyester strap mechanically stabilized earth (MSE) walls using a reliability theory-based approach. The calibrations are carried out using the simplified and stiffness...

The authors are investigating geosynthetic soil reinforcement techniques for the construction of emergency and restoration of damaged geostructures in the event of disasters. This paper discusses a geocell reinforcement technique for restoring embankments damaged by hydraulic action. A restoring technique to combine geocell reinforcements and horiz...

Recently, record-breaking short-duration heavy rainfall has caused extensive damage to soil structures. Reinforced soil walls have also been deformed by heavy rain, and countermeasures are urgently needed. In this study, alternating seepage flow and stability analyses evaluated the time series stability of a reinforced soil wall that collapsed due...

The technology of geosynthetic mechanically stabilized earth (MSE) walls can help solve classical geotechnical earth retaining wall problems. It can also contribute to achieving the new required performance for infrastructures, such as reliance and sustainability. To further develop this technology, it is essential to analyze the history of its pro...

The authors have studied geosynthetic basal reinforcement techniques for emergency and rehabilitation roads in the event of disasters. In this paper, the authors report the physical model tests of the geocell-reinforced ground under moving load conditions. The results of model tests of unreinforced and geocell-reinforced ground whose relative densi...

A reinforced soil retaining wall (RSRW) collapsed due to Typhoon No. 2 that made landfall in May 2011. The cause of the collapse is presumed to be that the water level in the back of the RSRW rose during rainfall, causing excessive water pressure to act on the RSRW, resulting in the reinforcement rupturing and reducing its stability. In this study,...

This document provides a summary of the different topics presented at the Special Session organized by the International Geosynthetics Society (IGS) Technical Committee on Soil Reinforcement (TC-R). This Special Session brings together very interesting studies regarding soil reinforcement in the field of geosynthetics. Studies presented include top...

This paper considers the sustainability of geosynthetics-based solutions to mitigate landslide risks. The different types of geosynthetics are briefly described, along with their functions and applications relevant to landslides, emphasizing reinforcement. The paper identifies the sustainability factors to consider when applying geosynthetics for t...

For the rational seismic design of railway embankments considering seismic risk, high-strength geomaterials and reinforcements should be used in areas with high seismic probability, and low-strength geomaterials and reinforcements should be used in areas with low seismic probability. In this study, a seismic probabilistic risk estimation of Japanes...

We have developed a vibration-reducing material for reducing the vibration that occurs during the running of heavy construction machinery. This vibration-reducing material is a pad made of polyolefin elastomer with 3D mesh structure. In addition to its vibration-damping effect, this material has excellent compression-resistant and vibration reducin...

A testing apparatus was developed to measure the permittivity of geotextiles under a wide range of hydraulic head difference conditions. Its validity was investigated experimentally, and an evaluation method of permittivity based on Izbash's law which is for non-Darcy flow in highly permeable porous media was discussed. In this paper, the experimen...

The authors study geosynthetic-soil reinforcement techniques for the emergency and rehabilitation roads in the event of disasters. This paper reports the results of a physical modeling investigation on the reinforcement mechanism of geocells under vertical loading conditions. Load-settlement relationships for four cases of model loading tests and t...

This study proposes a practical fragility estimation equation for Japanese standard models of railway embankments using the peak ground acceleration, peak ground velocity, and Arias intensity. The analytical models were implemented as unreinforced and geosynthetic-reinforced embankment models. A sensitivity analysis of the seismic fragility estimat...

In this study, experimental investigations were conducted to measure the ground displacement through particle image velocimetry (PIV) using colored sand. The effects of the mixing ratio of the colored sand, the number of pixels of the specimen’s image captured via a single lens reflex camera, the minimum measured displacement, and the subset size o...

The authors investigated a temperature-accelerated creep test under confining pressure conditions on a single-rib geogrid placed in a soil layer. A basic study was conducted on the fixing method of the geogrid to the loading device, the applying method of creep load considering the friction between soil and geogrid, and the adjusting method of the...

Long-term shaking table tests of unreinforced and reinforced retaining walls were conducted using a permanent magnet shaking table to investigate the effect of reinforcement installation and the effect of reinforcement length. The results showed that the unreinforced retaining wall collapsed brittleness at relatively small vibration energy due to y...

In this study, seismic hazard assessment was conducted to calculate the probability of earthquake occurrence in Japan using the strong-motion network observed since 1996. Then, a fragility assessment was conducted to calculate the limit state exceedance probability using the past proposed regression equation. Finally, the seismic probabilistic risk...

Ports, waterways and related coastal structures are very common in most countries. Geosynthetics as used in many other applications are also applicable to these structures for their better performance and cost-effectiveness compared with traditional materials. In this chapter, the applications of geosynthetics for quay walls, breakwaters, river emb...

In evaluating the stability of natural slopes that have multiple layers with different soil strength, the safety factors obtained by slope stability analysis using a circular slip surface are not guaranteed to be the smallest safety factors, but the safety factor with non-circular slip surface can obtain reasonable slip surfaces with a smaller safe...

Advanced soil reinforcement should be useful to carry out road restoration following a disaster. A deployable geocell reinforcement inspired by the self-deployable structure in space and mechanical engineering was designed for the road restoration. The deployment conditions and reinforcement shape were simulated. A series of laboratory tests were c...

With the growing interest in risk-based design, the choice of analysis method to estimate deformation, damage, and failure of geotechnical structures is important. The authors aimed to develop a SPH analysis method for analysis of reinforced soil walls. The general approach is based on the framework of the existing SPH analysis method. The fill mat...

Compaction grouting (CPG) is an in-situ grout injection technique used to improve the liquefaction resistance of loose sandy ground by densification and increasing lateral confining pressure. The present study investigates ground response during grout injection using a transparent granular soil and a natural sand soil. The injection process was sim...

Polyester (PET) strap MSE walls are gaining popularity in many countries. The writers compared measured tensile reinforcement loads from instrumented field walls under operational (working stress) conditions with predictions using the Coherent Gravity Method and the Simplified Stiffness Method. These methods are specified in the latest AASHTO code...

To investigate the effects of the reinforcement content on the mechanical behavior of short fiber-reinforced soil, direct shear tests were performed on the specimens wherein the reinforcing materials were arranged vertically. In the series of tests, a shear box test apparatus with a transparent acrylic side plate was used to visualize the internal...

To investigate the bearing capacity mechanism of a geogrid-reinforced foundation, the physical modeling technique of visualization using transparent soil was examined. Quartz glass and mixed mineral oil were used for the transparent soil. A polyethylene net was used for the geogrid. The movements of the soil and the geogrid under a strip loading we...

The paper demonstrates deterministic and reliability-based assessment of strength limit states (tensile resistance and pullout) and the service limit state for soil failure for mechanically stabilized earth (MSE) walls constructed with polyester (PET) strap reinforcement. The general approach considers the accuracy of the load and resistance models...

This paper demonstrates reliability-based design (RBD) and analysis for tensile strength (rupture) and pullout limit states for mechanically stabilized earth (MSE) walls constructed with steel grid reinforcement in combination with frictional soils. Five different reinforcement tensile load models for walls under operational conditions are consider...

This paper demonstrates reliability-based analysis of tensile strength and pullout limit states for mechanically stabilized earth (MSE) walls constructed with steel-strip reinforcement. Five different reinforcement tensile load models, three different pullout models, and one tensile strength model were examined. The accuracy of each model was asses...

This study describes the evaluation of earthquake-induced landslide susceptibility over a wide area. An index of landslide susceptibility is the seismic residual displacement calculated from a regression equation using a simple slope model. A method for creating a data file for estimating landslide susceptibility is discussed. The data file for the...

Slope stability analysis is one of the most intricate problems of geotechnical engineering because it is mathematically difficult to search the critical slip surface of earth slopes with complex strata owing to the involved multimodal function optimization problem. At present, a minimum factor of safety for a non-circular slip surface in a uniform...

The 2016 Kumamoto earthquake first occurred on April 14, 2016 with magnitude 6.5 in Kumamoto, Japan as a foreshock. Subsequently, after 28 h, an even larger earthquake occurred with magnitude 7.3 as the main shock on April 16, 2016. These earthquakes were caused by two active faults: the Futagawa and Hinagu faults. This paper proposes a landslide s...

Polyester (PET) straps are being used more frequently in mechanically stabilized earth (MSE) walls. At present, there is no consensus on a model or models that are suitable for design codes to calculate the pullout capacity of these materials. A database of 296 pullout tests from 81 test series with single and closely-spaced parallel double PET str...

Mechanically stabilized earth (MSE) walls must be designed with adequate margins of safety against internal stability failure described by tensile strength and pullout limit states. Probabilities of failure (or reliability index) will vary strongly with the accuracy of the underlying models that appear in limit state performance functions. In this...

Management of the earth structures is important to ensure proper functioning of roads. Given that Japan is home to many earth structures, the basic premise of earth structure management is to prevent traffic hazards by conducting regular inspections. New inspection methods are required to reduce the use of human resources involved in earth structur...

The focus of this paper is on quantitative evaluation of four different methods that use closed-form equations to calculate the nominal load in steel grid-reinforced soil walls under operational (end of construction) conditions. The four methods are the Coherent Gravity Method used in the UK, the AASHTO Simplified Method (USA), the PWRC Method used...

This study describes the life cycle cost of unreinforced and reinforced soil slopes subjected to seismic forces according to their seismic deformation. The life cycle cost is the sum of the initial construction cost obtained from the actual construction information and the reconstruction cost assumed based on certain reconstruction methods. From th...

Technical committee of IGS Japan chapter collected many case histories on collapsed or deformed geogrid reinforced soil walls. The range of wall height is from 4.0 m to 11.0 m, the maximum embankment height reaches about 20 m, and the range of slope inclination is from 1:0.1 to 1:0.5. Their backfills are mainly sandy soils. The observed failure mod...

Energy Grade Line Analysis (EGLA) of tsunami run-up has been proposed as a simple tool to predict inundation heights and tsunami loads. A large database of more than 500 inundation measurements collected on the Sendai Plain on the east coast of Japan after the Tohoku earthquake of 2011 provided the writers the opportunity to evaluate the accuracy o...

There are conflicting opinions regarding whether or not mechanically stabilized earth (MSE) walls constructed with polyester (PET) straps should be classified as relatively inextensible type, and thus fall into the same category as steel reinforced soil walls, or they should be viewed as relatively extensible and grouped with MSE walls that are des...

The 2016 Kumamoto earthquake hit Kumamoto City, of Kumamoto Prefecture, in Kyushu region in Japan on April 16, 2016. This study proposes a calculation method for regional earthquake-induced landslide susceptibility that uses the seismic residual displacement seismic motions. The proposed method takes into account the direction of slope failure base...

The 2016 Kumamoto earthquake hit Kumamoto City, of Kumamoto Prefecture, in Kyushu region in Japan on April 16, 2016. This study proposes a calculation method for regional earthquake-induced landslide susceptibility that uses the seismic residual displacement calculated by the Newmark’s sliding block analysis with estimated vertical and horizontal s...

The paper describes the first reported attempt to numerically simulate the performance of full-scale steel multi-anchor reinforced soil walls (MAWs) during construction using a commercially available two-dimensional finite element method (FEM) model. The numerical simulation results are compared to the measurements taken from three 6 m-high MAW str...

Steel grids in the form of bar mat and welded wire mesh are a common reinforcing material in mechanically stabilized earth (MSE) walls. This paper uses a large database of laboratory steel grid pullout tests from multiple sources to evaluate the accuracy of different ultimate pullout capacity models in a consistent statistical framework. Included i...

The paper describes a method of regional landslide susceptibility maps with permanent seismic displacement obtained from the Newmark method including a strong-motion accelerogram with a corresponding slope azimuth. To validate the proposed method, the newly created regional landslide susceptibility map was compared to an official landslide inventor...

This paper describes development of tsunami inundation database for applications to inundation analysis based on the post-event survey results in the 2011 off the Pacific Coast of Tohoku Earthquake. Data quality check, classification method, and adding of additional information were discussed for inundation analysis. Finally, total 680 point data w...

The probabilistic precipitation may have a difference due to the accumulation of observation data, but it is not taken into account in the design of soil structures. In this study, the difference of the probabilistic precipitation in a certain return period was investigated, using the observation data of the regional meteorological observatory and...

This study proposes a calculation method for regional earthquake-induced landslide susceptibility that applies the permanent seismic displacement calculated using Newmark’s sliding block analysis with estimated vertical and horizontal seismic motions. The proposed method takes into account the direction of slope failure based on the specified slope...

When conducting seismic stability analysis on reinforced slopes, the slip surface must be determined. To evaluate the stability of reinforced slopes comprising a homogenous foundation material, a seismic stability analysis using the circular slip surface is highly practical; however, for evaluating the seismic stability of reinforced slopes that ha...

The Arias intensity (IA) is the most comprehensive parameter for expressing the energy content of earthquake ground motion records. However, the predominant direction of the slope failure cannot be evaluated using IA because the value of IA does not depend on the direction of motion. The paper describes a method of regional landslide susceptibility...

A slope stability analysis method has a long history and various stability method have been proposed since the Fellenius method proposed in the 1930s. In practice, a circular slip surface has been generally used to calculate a safety factor, however, for evaluating the stability of reinforced slopes that have complex strata with weak layers, the sa...

Three case histories of damages of geogrid reinforced soil walls triggered by rainfall were collected. The probable mechanisms were identified, and actual countermeasures were reviewed. The walls had been constructed on valleys or sloped foundations in mountainous areas and damaged caused by the rainwater inflow which is over the drainage capacity....

This study aims to evaluate the stability of steal gabion mattress against tsunami-induced strong flow through hydraulic model tests. Performed tests are to observe the scaled mattresses on the mound under steady flow condition. The flow velocity was increased step by step and the relationship between number of damaged mattresses and the velocity w...

The development of microfocused X-ray computed tomography (CT) devices enables digital imaging analysis at the pore scale. The applications of these devices are diverse in soil mechanics, geotechnical and geoenvironmental engineering, petroleum engineering, and agricultural engineering. In particular, the imaging of the pore space in porous media h...

The development of a micro-focused X-ray CT device enables digital imaging analysis at the pore-scale. The applications have been diverse, for instance, in soil mechanics, geotechnical and geoenvironmental engineering, petroleum engineering, and agricultural engineering. In particular, imaging of the pore space of porous media has contributed to nu...

Two nominal identical 4 m high steel strip reinforced soil walls varying only with respect to reinforcement layer length arrangement were constructed and instrumented in an indoor laboratory environment. A novel feature of the tests was a foundation arrangement that allowed for simulated loss of toe support. Both walls performed well at the end of...

In pavement structure, short fiber reinforcing technique is hoped as an effective method for improving the stability of the subbase or subgrade layers against traffic load. In this paper, compaction behavior of short fiber reinforced is discussed by the results of laboratory compaction tests. As the results of roller compaction tests, it was confir...

Worldwide, many people depend on groundwater for daily drinking water. Groundwater contamination is being increasingly reported in recent years. The development of a rational remediation method is an important subject in geo-environmental engineering. This research project aims to develop a reliability-based remediation method for the pump-and-trea...

This paper reports the results of load and resistance factor design (LRFD) calibration for pullout limit states for geogrid reinforced soil walls owing to soil self-weight loading plus permanent uniform surcharge. The calibration method uses bias statistics to account for prediction accuracy of the deterministic models for reinforcement load and pu...

Large mattress using high strength geogrids for river or marine applications has been used to protect the erosion around the reasons for construction performance with its simple execution. This mattress has many desireble features on environmental performances for biological, chemical and carbon dioxide emission problems. This study aims to evaluat...

This paper reports the results of a novel experiment in which two nominally identical full-scale steel multi-anchor reinforced soil walls were taken to foundation failure by progressive loss of footing support. The 4-m high walls varied only with respect to reinforcement anchor lengths. The data show that facing displacements at end of construction...

This paper reports the results of a novel experiment in which two nominally identical full-scale steel multi-anchor reinforced soil walls were taken to foundation failure by progressive loss of footing support. The 4-m high walls varied only with respect to reinforcement anchor lengths. The data show that facing displacements at end of construction...

The paper presents the results of three full-scale tests that were carried out to investigate the influence of transient (cyclic) flooding on the performance of steel strip reinforced soil walls (SSWs). The walls were constructed to a height of 6 m and then flooded and drained to about mid-height in four cycles. The walls were constructed with thre...

This paper reports the results of three 4m high full-scale instrumented geogrid-reinforced soil walls constructed with different structural facings having a range of stiffness. The walls were seated on a 2m deep foundation layer that was laterally supported at the base of the wall face by a rigid bulkhead. Following end of construction, the bulkhea...

A mechanically stabilized earth wall with steel strip soil reinforcement was built and instrumented by the Public Works Research Institute of Japan. Measured reinforcement loads and vertical toe loads are compared to values predicted using the finite difference program FLAC. Backfill and foundation soil properties were not reported in the original...

The paper uses statistical data for the prediction of installation damage and creep-reduced strength collected by the writers in earlier investigations to estimate the probability of failure of tensile rupture of geogrid reinforcement products. The original data were compiled from Public Works Research Center (PWRC) geogrid product certification re...

The paper reports the results of the analysis of field installation damage tests carried out on geogrid soil reinforcement products used in Japan. The data are taken from Public Works Research Center (PWRC) product certification reports. The database comprises a total of 130 tensile tests performed on undamaged (reference) tests and 390 tensile tes...

The serious damage of breakwaters occurred in the tsunami caused by the 2011 off the Pacific coast of Tohoku earthquake. It is important to reinforce breakwaters with the concrete blocks and to give the function of tenacious structures. Hydrodynamic experiments had been performed to study the damage of concrete blocks armoring on rubble mounds for...

A tsunami caused by an earthquake off the Pacific coast of Tohoku seriously damaged many coastal structures. It is important to reinforce these structures with the concrete blocks and to give the function of tenacious structures. In case of coastal dikes, the stability of concrete blocks and the damage of coastal dikes are affected by the fluid for...

This paper examines dissipation of tsunami due to overflow over different shapes of dike by hydraulic experiments. The experimental results were compared and validated against the classical theory of weir. Experimental results showed that a dike with slope on upstream side and vertical back side is the most effective to reduce the tsunami energy. A...

In Japan, innovations leading to lower maintenance and repair costs for asphalt pavement structures are required. For a general roadway in Japan, it is only possible to apply a soil reinforcing technology that is equivalent to excavating and backfilling concerned with maintenance of lifeline facilities. In this study, therefore, model loading tests...

The data collected by creep testing carried out in conformity with current Japanese practice and reported in Public Works Research Center product certification reports are interpreted in order to identify and discuss differences between current Japanese practice and European and US practices. A database of 66 different geogrid products from 10 diff...

The 2011 Tohoku earthquake off the Pacific coast of Japan (Mw = 9.0) contained a huge source region of approximately 450 km by 200 km and caused extensive damage to various structures. Damage caused by the tsunami was tremendous and many lives were lost. In addition to the damage to concrete structures, seawalls were seriously damaged, probably as...

This paper discusses a tsunami-resistant structure with geogrid. The results of flume tests to investigate the effect of the structural shape on tsunami-energy dissipation showed that a structure with slope on the upstream side and vertical face on the downstream slide is the most resistant. A geo-structure with a geogrid gabion system is proposed....

Asphalt pavement has structural problem that is low durability against traffic loads and environmental interaction. In Western countries, reinforcing technologies using geosynthetics have often been used to reinforce the base layer to improve the stability. On the other hand, studies on the application of soil reinforcing technologies such as geosy...

For reinforced soil walls, the judgment of the healthy-unhealthy is usually carried out by the uniform control value, such as wall displacement. However, it is believed that many reinforced soil walls are stable with some deformation with age. The authors have proposed a maintenance method not monitoring a uniform control value but judging the pres...

This paper discusses the effect of the damage level on the seismic stability of a geogrid-reinforced soil wall with a divided facing panel system based on the results of 1g tilt-table tests. The model had a height of 810 mm, length of 1650 mm, and width of 500 mm. The fill material was sandy soil, and the geogrid was connected to the divided facing...

This paper discusses the effects of inadequate compaction near facing on the seismic stability of geogrid reinforced soil walls (GRSWs) with divided facing panel systems. To investigate the effects, centrifuge shaking table tests were conducted under centrifugal acceleration of 20 G. Seismic loads using Kobe and sinusoidal waves were applied to GRS...

This study focused on a reinforcing method that used short fibers to reinforce the gravelly soil applied as the base course of an asphalt pavement structure. The fundamental performances of the fiber reinforced gravelly soil, such as the structure of the fiber mixed soil, compaction properties, and strength properties, were investigated using labor...