Foundation Damage of Structures in Kobe and Remediation

In this paper, foundation damage of structures in the 1995 Hyogoken-Nambu Earthquake was overviewed, mainly focusing on that of bridges and elevated highways, port and harbor facilities and buildings. Then, the remediation methods and works for damaged foundations were summarized, together with illustrating some examples. Finally, essentials of related subjects and suggestions on seismic design and remediation for foundations of structures were summarized for a further study

Case Histories and Vibratory Characteristics of Vibro-driven Piles

The vibratory characteristics of vibro-driven piles into the ground have not so far been discussed systematically in detail. This paper concerns the results of monitoring vibro-driven piles in various types of ground. In order to assess the monitoring of vibration performance, time-series monitoring data on the reaction force at the pile tip and the vibratory acceleration of the pile top are analyzed in relation with the soil profiles of four monitoring sites. As the result, it has been elucidated that the pile tip reaction force and vibratory acceleration are systematically presented by the dynamic force and the mass weight of the vibrohammer and pile. Furthermore, engineering applications of the vibratory characteristics of vibro-driven piles are presented

Seismic Ground Settlement and Deformation Behavior of Reclaimed Lands in the 1995 Kobe Earthquake

After the 1995 Kobe Earthquake, particular attention has been paid on the settlement observed at reclaimed lands located at between Osaka and Kobe, in reference to their geological characteristics. In this paper, the ground surface elevations before and after the 1995 Kobe Earthquake were compared to evaluate the seismic ground settlement of reclaimed lands. Calculated settlements by using an available empirical formula were compared with measured ones. A further study was carried out to investigate the seismic ground settlement calculated by using a numerical simulation program called “FLIP” at a selected reclaimed land. In reference to the data available from published papers on seismic ground settlement as measured, attempts were made to identify in a practical manner such settlement with the degree of the earthquake recorded at each reclaimed lands as well as the grain size and N value of the filled layer there. The proposed method for estimating seismic ground settlement caused by earthquake is estimated for its applicability and accuracy by using a simulation program

Degradation of Saturated Clays after Cyclic Loading

This paper presents a part from a series of tests performed to evaluate the static shear behavior of normally consolidated and over-consolidated clays after cyclic loading effect. The results demonstrated that the static undrained stress-strain behavior of these types of clays was affected by their relative stiffness. Based on the equivalent over-consolidation hypothesis and the experimental results it was able to construct the shear characteristics degradation relationships for the normally consolidated clays. The predicted results were compared with the measured test data and their well agreement was confirmed

A Field Study and Dynamic Finite Element Analysis of Railway Retaining Structures Damaged by the Hyogoken-Nambu Earthquake (1995)

The seismic damage to embankments and retaining walls caused by the Hyogoken-nambu Earthquake (1995) was reviewed, rather focusing on railway structures. Nearly eight kilometers of damaged retaining structures were divided into five structural types, such as gravity-type walls, leaning-type walls, embankments, geo-textile-reinforced earth walls, and reinforced concrete walls, and into three categories of the damage, such as collapse, tilt, and crack. It was observed that the damage to gravity-type and leaning-type walls was greater than that to embankments, geo-textile-reinforced earth walls, and reinforced concrete walk, when they are lower than five meters. But some leaning-type walls higher than seven meters remained un-collapsed. In a smaller limited section, damage analyses of stone masonry walls of gravity type were carried out including undamaged ones. The percentage of heavy damage to stone masonry walls with slopes was nearly twice larger than that without slopes. Moreover, two-dimensional dynamic non-linear finite element analyses were performed on a gravity-type wall, a leaning-type wall, and a geo-textile-reinforced earth wall. As the results, it was pointed out that the gravity-type and leaning-type walls developed slide or gap against the backfill. But the gee-textile-reinforced earth wall developed tension in the reinforced material and it prevented the wall from leaning or sliding

Field Measurement on a Slope Cutting With Tensile Inclusions

In a road widening project, tensile inclusions were used to stabilize some parts of cut slope works. The site condition and the construction of reinforced slope cutting are presented. A full scale field test on a reinforced cut slope was performed being incorporated with this road widening project. The field test consisted of a field loading test and a field excavation test. Details of the field test, field measurements and site observation are presented. Finite element analysis of the field test is performed. Based on the field measurements together with the analytical results, the reinforcement mechanism of a reinforced cut slope under a surcharge load and that under an effect of excavation are discussed

Effectiveness of Compaction Grout Piles in Improving Foundation Soils of Existing Runway

Compaction grout piles were used to minimize the liquefaction potential of the foundation soils of Tokyo International Airport at the intersection area of the two runways A and B. The compaction grout piles were intermittent to treat only the liquefiable soil layers and of varying diameter to account for the variable condition of the treated soils. This paper describes the performed grouting works and presents improvement results for one of the grouting stages. The presented results reveal the effectiveness of the adopted design and procedure in improving the liquefiable soils. The paper also discusses the improvement results with emphasis being on the obtained improvements at the vertical boundaries of the treatment zones. The discussion suggests that there is a loss of improvement at the boundaries and this loss is attributed to the boundary effect and the effect of variation of soil compressibility around the boundary of treatment zone. A correlation between a newly presented index called relative compressibility index (RCI) and the improvement at the boundary is identified. This correlation is useful in planning the intermittent treatments by compaction grout piles and implies that the loss of soil improvement at the boundary of treatment zone increases as RCI decreases

Ground Vibrations Isolation by PC Wall-piles

This paper presents the results of a series of experiments conducted on a PC wall-piles barrier. That barrier was built alongside a road passing through some sensitive sites, to assess its effectiveness in isolating vibration caused by running trains and dropping a weight. Then the effectiveness of PC wall-piles for controlling ground vibrations is discussed. Field measurements were performed for 5 cases having different types of PC wall-piles. The simultaneous measurement of vibration was performed at several selected points on the ground. Finally, a method for estimation of vibration reduction by PC wall-piles was developed, being based on wave penetration theory. The major findings from this series of experiments are as follows: 1. Vibration level as registered on the off-side of the PC wall-pile harrier was found to be 5 to 7 dB lower than that recorded at the site with no such barrier. 2. The maximum isolation effectiveness was obtained in the case of hollow PC wall-piles. 3. The theoretical results using the wave penetration theory showed a good agreement comparing with the field tests

Analytical Evaluation for Seismic Behavior of Shore Structures on Liquefied Area During Earthquakes

In this paper, focusing on the caisson type quay wall, which is a typical gravity type of shore structures, the seismic behavior of the structures was discussed when the liquefaction occurs, by applying the dynamic response analysis and a simplified prediction method which was proposed by the authors. Firstly, a simplified and reasonable method for predicting the seismic behavior of shore structures during earthquakes was proposed. In the proposed analytical method, the structure is replaced by a simplified model, and the ground contacting the structure by subgrade springs. There are two types of subgrade springs employed as elasto-plastic spring and liquefied spring. Secondly, the seismic behavior of shore structures in liquefied areas was evaluated through case study by dynamic response analysis. As the result, it was elucidated that the residual horizontal displacement of structures depends on the maximum horizontal acceleration acting at the center of structures, and the duration of earthquake motion is closely related to the residual horizontal displacement. It is also confirmed that the residual horizontal displacement of irregular seismic wave is 1/3 to 2/3 times smaller than that of regular seismic wave. After then, in order to confirm the applicability of the proposed simplified prediction method, a case study was performed to compare the result of the simplified analysis with that of the dynamic response analysis. As the result, the relationships between the horizontal acceleration at ground surface and the residual horizontal displacement by both analyses without liquefaction showed a similar trend, while those with liquefaction showed different trends, which was due to the difference of evaluating the semi-liquefaction, It was confirmed that the proposed simplified prediction method was applicable to predicting the actual seismic behavior of shore structures with good accuracy by adequately adjusting the reduction ratio of liquefied spring in the semi-liquefaction condition

Co-culturing of follicles with interstitial cells in collagen gel reproduce follicular development accompanied with theca cell layer formation

<p>Abstract</p> <p>Background</p> <p>The mechanism of theca cell layer formation in mammalian ovaries has not been elucidated; one reason is that there is no follicle culture system that can reproduce theca cell layer formation in vitro. Therefore, a three-dimensional follicle culture system that can reproduce theca cell layer formation is required.</p> <p>Methods</p> <p>A collagen gel was used in the follicle culture system. To determine the optimum conditions for follicle culture that can reproduce theca cell layer formation, the effects of hormonal treatment and cell types co-cultured with follicles were examined. In addition, immunohistochemistry was used to examine the properties of the cell layers formed in the outermost part of follicles.</p> <p>Results</p> <p>Follicles maintained a three-dimensional shape and grew in collagen gel. By adding follicle-stimulating hormone (FSH) and co-culturing with interstitial cells, the follicles grew well, and cell layers were formed in the outermost part of follicles. Immunohistochemistry confirmed that the cells forming the outermost layers of the follicles were theca cells.</p> <p>Conclusion</p> <p>In this study, follicle culture system that can reproduce theca cell layer formation <it>in vitro </it>was established. In our opinion, this system is suitable for the analysis of theca cell layer formation and contributes to our understanding of the mechanisms of folliculogenesis.</p