Volcanic mountain area disaster caused by the Iwate–Miyagi Nairiku Earthquake of 2008, Japan

We conducted an investigation of the geotechnical damage caused by an earthquake that struck on June 14, 2008. The earthquake was of magnitude 7.2 and hit a volcanic mountain area in Northern Japan. During the earthquake, the largest strong motion ever, over 4G, was recorded at the ground surface in the source region. As a result of the earthquake, a landslide of 1.5 million m³ was generated near the top of the mountain and became a mud flow, traveling about 10 km downstream. The geomorphic characteristics of the mud flow are reported in this paper. Another huge landslide was generated upstream near the Aratosawa Dam. It was about 1 km in length, about 700 m in width and had a sliding mass volume of about 67 million m³, which slipped about 320 m. The geological features, the time series of the slide and the cause of the slide are also discussed. In addition, more than 50 landslide dams, formed due to the collapsed soil and rock, appeared after the earthquake. In this paper, the geotechnical properties of all the damage are introduced.     

Effect of earthquake ground motions on soil liquefaction

During the 2011 off the Pacific Coast of Tohoku Earthquake, which was the largest earthquake in Japanese history, the soil liquefaction phenomenon was observed over a wide area along the Pacific Coast in Tohoku and in Kanto, including the Tokyo Bay area. Extensive damage was caused by the effect of soil liquefaction to residential lands and houses, as well as to infrastructures, such as roads, rivers, ports, and water supply/sewage systems. Since the 2011 off the Pacific Coast of Tohoku Earthquake occurred in a mega-size fault zone, with an area of 500 km×200 km, the duration of the strong shaking was extremely long compared to that in the data recorded for past earthquakes. Clarifying the effect of the characteristics of the ground motion on the soil liquefaction mechanism is one of the essential studies to be conducted, and effective countermeasures for the damaged structures need to be found.This paper presents the strong motion observation data obtained on the liquefied and the non-liquefied grounds and raises preliminary discussions on the mechanism of soil liquefaction based on this data. The effect of the duration and the number of cyclic loadings on the progress of the soil liquefaction phenomenon is also compared with that found in past strong motion data.     

Building damage associated with geotechnical problems in the 2011 Tohoku Pacific Earthquake

An overview of the geotechnical aspects of the building damage due to the 2011 Tohoku Pacific Earthquake is presented, based on field reconnaissance made after the earthquake. It is shown that (1) Extensive soil liquefaction occurred along the coast of Tokyo Bay and around the floodplain of the Tonegawa River. Liquefaction was primarily found within the relatively newly reclaimed area, with numerous sand boils and large ground settlements up to 60 cm, accompanied by the settlement/tilting of wooden and reinforced concrete buildings supported by spread foundations. The extent and the distribution of the damage were significantly affected by the local soil conditions, including the thickness and the age of the reclaimed fills, the depth to the bedrock or the natural site period, and whether remedial measures had been taken against soil liquefaction, as well as the effects of structure–soil–structure interaction. (2) Numerous houses in Sendai's hilly residential areas constructed with the cut-and fill method were badly damaged not only by the simple collapse of retaining walls, but also by slope failures in the fills. It was found that most of the slope failures occurred on earth fills. (3) Several pile-supported buildings tilted and settled not only in the Tohoku region, but also on the Kanto plain, implying damage to pile foundations. Ground subsidence with sand boils around those buildings suggests that soil liquefaction might have played a significant role in intensifying the damage. (4) Within Onagawa and Rikuzen-Takata, several steel and reinforced concrete structures were knocked over by tsunami surges, probably after having suffered damage to their pile foundations. Much of the pile damage was concentrated (a) at the joints between pile caps and the piles themselves and (b) near the pile heads. The buildings suffering such damage were old; apparently their pile foundations were not designed to withstand earthquakes.     

Damage to coastal structures

On March 11, 2011, the largest earthquake ever recorded in Japan struck off the coast of the Tohoku region of the country, and was subsequently named the 2011 off the Pacific coast of Tohoku Earthquake by the Japan Metrological Agency. The M_w 9.0 earthquake generated strong motions that affected the island of Honshu from Tokyo Bay to the northern extent of the island, and induced a series of tsunamis that devastated coastal communities throughout the region. Significant aftershocks (M_w>7) were experienced that further contributed to damage in the coastal Tohoku region during emergency response and recovery efforts. This paper summarizes the findings of the Port and Airport Research Institute (PARI) research team as it investigated coastal structures along approximately 600 km of coastline as well as the team׳s follow-up experiments and analyses. Two characteristics of the ground motion observed were the long duration and the high-frequency component. For this reason, the degree of damage caused to coastal facilities by the ground motion was relatively small. The wide-ranging investigation by the PARI team facilitated the interpretation of damage patterns across the entire region affected by the earthquake, with a primary goal of distinguishing damage to coastal structures resulting from strong ground shaking and secondary effects (such as liquefaction, ground failures, and settlement) from that caused by the subsequent and significant tsunami inundation.     

Landslide and mudflow disaster in disposal site of surplus soil at Higashi-Hiroshima due to heavy rainfall in 2009

The collapse of a filling occurred due to heavy rain in Higashi-Hiroshima City׳s Shiwa District at about 5:30 am July 25th, 2009. The filling was made of surplus soils, and it contained a mass of water supplied from rainfall and ground water flow of a permeable layer at the bottom of the filling. The collapsed soil flowed down and destroyed a house. In this paper, the cause of this disaster is discussed. The site of the disaster was used as the dumping site of surplus soils, after several changes of ground formation. The history of the geographical change was reconstructed by the image processing of old map, aerial photographs, result of 3-dimentional laser survey carried out after collapse and the measurement of thickness of collapsed soil by dynamic cone penetration test. According to the result of processing, the shape and the size of the filling before collapse was reconstructed. The relationship between the rainfall and the groundwater in the river sediments layer over which the filling was constructed was determined. A stability analysis of the filling was conducted considering the rise of the groundwater level in the filling and the laboratory measured strength parameters. The results of the stability analysis showed that the collapse would have taken place when the groundwater level rose by about 9 m due to the supply of groundwater through the river sediments layer.     

Extreme selenium and tellurium contamination in soils — An eighty year-old industrial legacy surrounding a Ni refinery in the Swansea Valley

Elevated levels of selenium (maximum 200 mg/kg) and tellurium (maximum 11 mg/kg) are reported in topsoils (< 5 cm) from around a long-established nickel refinery at Clydach in the Lower Swansea Valley, UK. Se and Te are correlated with each other and when these data are plotted as contour diagrams they show a concentric pattern centred on the refinery site. The origin of the Se and Te contamination is investigated. A review of the changes in the refinery practices at the site is presented and used to link the soil contamination to industrial pollution which took place over 80 years ago. The most recent air quality data available cannot rule out some Se contamination up to 2003.     

Stability of pile foundations base on warming effects on the permafrost under earthquake motions

The Qinghai–Tibet Railway (QTR) is approximately 1142 km long, of which 275 km are underlain in warm permafrost regions (mean annual round temperatures range from 0 °С to 1.5 °С), where the stability of the embankment would be greatly affected by minor temperature variations. Furthermore, since the Qinghai–Tibet Plateau (QTP) is in an active seismic zone, special attention needs to be paid to the relationship between earthquakes and soil temperature. Using a refrigeration system, a series of shaking table tests for the 1/100 scaled model of the pile foundation in the Qingshui-river Bridge along the Qinghai–Tibet Railroad were conducted for soil temperatures of below 0 °С around the pile. The results indicated that the seismic mechanical properties are extremely sensitive to soil temperature. The change of temperature around the pile foundation during the earthquake motions was monitored, and the warming effects on the permafrost were assessed. In addition, the seismic stability coupled with the effect of soil temperature of the pile foundation in the Qingshui-river Bridge was evaluated.     

Testing and analysis of a laterally loaded bridge caisson foundation in gravel

This paper presents the results of an in situ lateral load test on a caisson-type foundation of the old Niu-Dou Bridge in Ilan County, Taiwan. The caisson was 12 m long and had circular cross-sections whose diameters were 5 m in the upper portion and 4 m in the lower portion. The test site was located on soil with a high gravel content. A site investigation, including laboratory and field tests, was carried out. A six-component Winkler-beam model was applied to simulate the caisson response in the lateral load test. To determine the nonlinear properties of the Winkler springs, a method based on large-scale geotechnical field testing was proposed. With this method, the soil springs could be properly set and the Winkler-beam model could reasonably capture the lateral behavior of the caisson foundation.     

Seismic performances of dyke on liquefiable soils

Various field investigations of earthquake disaster cases have confirmed that earthquake-induced liquefaction is a main factor causing significant damage to dyke, research on seismic performances of dyke is thus of great importance. In this paper, seismic responses of dyke on liquefiable soils were investigated by means of dynamic centrifuge model tests and three-dimensional (3D) effective stress analysis method which is based on a multiple shear mechanism model and a liquefaction front. For the prototype scale centrifuge tests, sine wave input motions with peak accelerations 0.806 m/s², 1.790 m/s² and 3.133 m/s² of varied amplitudes were adopted to study the seismic performances of dyke on the saturated soil layer foundation with relative density of approximately 30%. Then, corresponding numerical simulations were conducted to investigate the distribution and variations of deformation, acceleration, excess pore-water pressure (EPWP), and behaviors of shear dilatancy in the dyke and the liquefiable soil foundation. Moreover, detailed discussions and comparisons between numerical simulations and centrifuge tests were also presented. It is concluded that the computed results have a good agreement with the measured results by centrifuge tests. The physical and numerical models both indicate that the dyke hosted on liquefiable soils subjected to earthquake motions has exhibited larger settlement and lateral spread: the stronger the motion is, the larger the dyke deformation is. Compared to soils in the deep ground under the dyke and the free field, the EPWP ratio is much smaller in the shallow liquefiable soil beneath the dyke in spite of large deformation produced. For the same overburden depth soil from free site and the liquefiable foundation beneath dyke, the characteristics of effective stress path and stress–strain relations are different. All these results may be of theoretical and practical significance for seismic design of the dyke on liquefiable soils.     

Design and construction of river crossing tunnel beneath Tachia River,Taiwan

Due to the impact of the 1999 Chi-Chi earthquake (ML = 7.3) and the following typhoon induced heavy rainfalls and floods, the tailrace tunnel of the Kukuan Hydropower Plant was severely blocked and must be realigned and rebuilt. The new tailrace tunnel is 1991 m long with a 140 m section passing underneath the Tachia River, where the shallowest rock cover is 3.5 m. In view of the common phenomenon that weak zone developed along river channel and debris accumulated on river bed, the ground improvement from the surface to the tunnel is difficult. Therefore, a construction shaft, a water sealing pre-grouting plan and a special supporting system were designed to prevent the potential water inflow when tunneling underneath the Tachia River. In the construction phase, adequate excavation cross sections, support elements, auxiliary treatments, and water sealing grouting methods were selected to overcome the difficult ground condition encountered. The experience learned from this successful case can be a valuable reference for the design and construction of similar river crossing tunnels in the future.     

The Past,Present and Future of the Geo-Environment in Japan

This paper is an overview of the status in geo-environment research in the past, the present and the future in Japan as witnessed by the publications in “Soils and Foundations” over the years. The authors have paid special attention to the geotechnical researches concerning technologies of waste disposal, including radioactive waste disposal, the reuse and recycle of by-product and waste, the evaluation of the environmental impact of waste and by-product, and countermeasures and adaptations to the contamination of ground/groundwater. Some representative papers on the geo-environment published in “Soils and Foundations” have been drawn on heavily in this paper. The commentary provided by the authors is largely from a geo-environmental perspective. In addition, the authors have also paid attention to geotechnical issues in the research.     

Excavation failure during micro-tunneling in fine sands: A case study

Partly funded by the World Bank, a new gravity sewer line is currently being constructed in Anzali, Iran using micro-tunneling methods. The project includes the installation of 2551 m reinforced concrete pipes with diameter ranging from 600 to 1000 mm at an average depth of 5 m below surface. Micro-tunnel Boring Machine (MTBM) and hydraulic pipejacking have been used to install the sewer line. Pipejacking in saturated highly porous sandy soil poses various challenges during construction including the risk of face failure, possibility of shaft collapse, massive rush of groundwater (in this case from the Caspian Sea) and surface subsidence. This paper provides an overview of the project and summarizes the challenges faced and the techniques used to handle the difficulties encountered during construction.     

Field investigation and model tests on differential settlement of houses due to liquefaction in the Niigata-ken Chuetsu-Oki earthquake of 2007

A massive earthquake struck the Niigata Chuetsu-Oki region of Japan on July 16th, 2007, claiming 11 lives and damaging about 6000 houses. The earthquake had a magnitude of 6.8, with data from an accelerograph managed by a nationwide strong-motion observation network known as Kyoshin Net (K-net) showing a maximum value of 668 gal (NS). In the Matsunami district of Kashiwazaki city (located on land filled and developed as a residential area from around 1970 onward) about 3 km northeast of Kashiwazaki Railway Station, many houses were damaged due to liquefaction. A field investigation, including a boring survey, surface wave exploration and measurement of differential settlement of houses knocked aslant by soil liquefaction, was conducted to determine the relationship between the extent of damage to houses and the area׳s geological structure. It was found that most houses severely damaged due to liquefaction were located around the boundary between sand dunes and the local river delta. Additionally, the relationships linking sloping geological structure, the thickness of the liquefaction layer and total/differential settlement of houses were clarified from the results of shaking table model tests conducted in this study. Test results showed that it is important to consider multidimensional influences caused by sloping geological structure in the estimation method of liquefaction potential in order to predict and assess degree of damage to houses due to liquefaction.     

Daily urinary excretion of uranium in members of the public of Southwest Nigeria

The main aim of this study was to determine and evaluate urinary excretion values of uranium in members of the public of Southwest Nigeria living in areas of low environmental uranium. As several uranium mines are running in Nigeria and the operations could be a risk of contamination for the workers as well as for the members of the public, biomonitoring of urine could provide information about the exposure to uranium for the subjects. Therefore, baseline values of uranium in urine are needed from subjects living in areas without mining activities. Volunteers of both genders (age range 3 to 78 years) were asked to collect 24 h-urine samples. The concentration measurements of uranium in urine were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In addition, urinary creatinine values were determined for normalization of the renal uranium relative to the creatinine concentrations.The urinary uranium concentrations and their creatinine normalized values ranged from < 10.4 to 150 ng L^? 1 (median 13.8 ng L^? 1) and from 2.52 to 252.7 ng g^? 1 creatinine (median 33.4 ng g^? 1 creatinine), respectively, for adult subjects above 15 years of both genders. An increased uranium excretion value of 61.6 ng L^? 1 (median), and of 76.0 ng g^? 1 creatinine, respectively, were found in young subjects below 15 years. The median of daily excreted uranium was estimated to be 14.2 ng d^? 1 for adults and of 45.1 ng d^? 1 for children, respectively. The uranium excretion from males and females living in Nigeria in a non-mining area was comparable to reference values reported from other countries with low level of environmental uranium. The data can be considered as baseline values of urinary uranium in unexposed subjects in Nigeria.     

Tension in geomembranes on landfill slopes under static and earthquake loading—Centrifuge study

Geomembranes are some of the most commonly used geosynthetics in landfill liner systems. Geomembranes may experience harsh environmental conditions such as extreme temperatures or earthquake loading. Earthquake loading can be an extreme loading case for landfills located in seismic regions. This study, based on dynamic centrifuge testing, investigates the effects of simulated earthquake loading on the tension experienced by the geomembrane on a landfill slope. The landfill modelled in the dynamic centrifuge tests was a 7 m high municipal solid waste (MSW) landfill with a single geomembrane-clay liner system (45° side slope and 10 m slope length). Results show that moderate earthquake loading (base acceleration between 0.1 and 0.3 g) can result in a permanent increase in geomembrane tension of 5–25%.     

Scale similarity on ceiling jet flow

In this study, empirical formulae previously derived for describing the decrease in temperature rise, the decrease in velocity, the thermal boundary layer thickness, the momentum boundary layer thickness, the Gaussian thermal thickness, and the Gaussian momentum thickness of a ceiling jet flowing upward along the steepest run of an inclined ceiling were applied to a full-scale scenario. The coefficients in these formulae were determined through a series of pool fire tests conducted using a flat, unconfined model ceiling with dimensions of 2.5 m×3.0 m, and fixed ceiling clearance of 1.0 m. To verify the applicability of the developed formulae to actual fires, another series of pool fire tests were conducted using a flat, unconfined full-scale ceiling with dimensions of 7.0 m×14.0 m and a maximum ceiling clearance of 3.0 m. The proposed formulae were confirmed to be applicable to a full-scale scenario and to describe the ceiling jet flow accurately.     

Production of non-constructive concrete blocks using contaminated soil

In this research, a heavily contaminated humus-rich peat soil and a lightly contaminated humus-poor sand soil, extracted from a field location in the Netherlands, are immobilized. These two types of soil are very common in the Netherlands. The purpose is to develop financial feasible, good quality immobilisates, which can be produced on large scale.To this end, two binder combinations were examined, namely slag cement with quicklime and slag cement with hemi-hydrate. The mixes with hemi-hydrate proved to be better for the immobilization of humus rich soils, having a good early strength development. The heavily contaminated soil with 19% humus (of dm) could not be immobilized using 398 kg slag cement and 33 kg quicklime per m³ concrete mix (binder = 38.4% dm soil). It is possible to immobilize this soil using 480 kg binder (432 kg slag cement, 48 kg quicklime) per m³ of mix (58.2% dm). An alternative to the addition of extra binder (slag cement with quicklime) is mixing the soil with sand containing particles in the range of 0–2 mm. This not only improved the compressive strength of the immobilisates, but also reduced the capillary absorption. All the mixes with the lightly contaminated soil were cost-effective and suitable for production of immobilisates on a large scale. These mixes had good workability, a good compressive strength and a low capillary absorption. The leaching of all mixes was found to be much lower than allowed by the regulations. Given these results, the final mixes in the main experiment fulfilled all the financial and technical objectives.     

Performance of deteriorated corrugated steel culverts rehabilitated with sprayed-on cementitious liners subjected to surface loads

A variety of alternatives to rehabilitate culverts have been developed over the past decades given their advantages over conventional open-cut culvert replacement. However, the performance of many of these systems has not yet been examined through laboratory testing. The objective of the present paper is to examine the performance of deteriorated steel culverts rehabilitated with spray-on liners when subjected to surface loads. Two 1200 mm diameter corrugated steel pipelines with similar levels of deterioration in the invert-haunch area were buried to a depth of 1200 mm and tested under service load employing a load frame simulating a single axle of a Canadian design truck. The pipelines were then rehabilitated with spray on-cementitious liners (each with a different target thickness). Once rehabilitated, the pipelines were examined again under the service load employing the single axle load frame at 1200 mm of soil cover, and then tested employing a tandem axle load frame at 2100 and 1200 mm of soil cover. During all tests, changes in diameter, curvature and liner strains were monitored. The data obtained indicates that the flexible pipelines responded like semi-rigid structures after rehabilitation. It was also observed that the difference in liner thickness of 30% did influence the response of the pipelines, and that extreme fiber tensions during service loading were 7% and 13% of the tensile strength of the liner materials for the 76 mm and 51 mm liner thicknesses that were specified.     

Seismic behavior of piled raft with ground improvement supporting a base-isolated building on soft ground in Tokyo

The static and seismic behavior of a piled raft foundation, supporting a 12-story base-isolated building in Tokyo, is investigated by monitoring the soil–foundation–structure system. Since the building is located on loose silty sand, underlain by soft cohesive soil, a piled raft with grid-form deep cement mixing walls was employed to cope with the liquefiable sand as well as to improve the bearing capacity of the raft foundation. To confirm the validity of the foundation design, field measurements were carried out on the ground settlements, the pile loads, the contact pressure and the pore-water pressure beneath the raft from the beginning of the construction to 43 months after the end of the construction.On March 11, 2011, 30 months after the end of the construction, the 2011 off the Pacific coast of Tohoku Earthquake struck the building site. The seismic response of the ground and the foundation–structure system was successfully recorded during the earthquake, and a peak horizontal ground acceleration of 1.75 m/s² was observed at the site of the building. Based on static and dynamic measurement results, it was found that there was little change in the foundation settlement and the load sharing between the raft and the piles before and after the earthquake. It was also found that the horizontal accelerations of the superstructure were reduced to approximately 30% of those of the ground near the ground surface by the input losses due to the kinematic soil–foundation interaction in addition to the base isolation system.Consequently, the piled raft with grid-form deep cement mixing walls was found to be quite stable in the soft ground during and after the earthquake.     

An introduction to the development for urban underground space in Helsinki

Helsinki has developed a dedicated Underground Master Plan for its whole municipal area, not only for certain parts of the city. This work began in the 1980s and from then the City of Helsinki has maintained an underground space allocation plan. On average, under each 100 m² of surface area in Helsinki there is 1 m² of underground space. Consequently, there are still many underground resources for future needs existing within the whole city area. The Underground Master Plan of Helsinki shows both existing and future underground spaces and tunnels, as well as existing vital access links to the underground. It also includes rock resources reserved for the construction of as yet unnamed underground facilities. The development of the master plan has resulted from a long-term commitment of many public and private stakeholders to the planning process, the creation of a suitable legal framework and the collection and management of the data on geotechnical conditions and underground facilities.