Cyclic Torsional Shear Tests to Obtain Dynamic Soil Properties for Seismic Design of Road Embankments

Many road embankments have suffered damage during past earthquakes. The authors took soil samples from several embankments and conducted laboratory tests to demonstrate the mechanism of the damages and study appropriate seismic design methods. In the laboratory tests, cyclic torsional shear tests were carried out to obtain undrained cyclic strength, excess pore water pressure and shear modulus after cyclic loading of embankment soils. Test results showed a unique relationship between Plasticity Index and undrained cyclic strength is existed. Relationship between excess pore water pressure ratio and safety factor against liquefaction is also influenced by Plasticity Index. Then appropriate seismic design methods by applying these test results are discussed

Geotechnical Aspects of Recent Japan Earthquakes

Recently middle class earthquakes have occurred and caused various geotechnical damages every year in Japan. Among them geotechnical damages during five earthquakes from 2004 to 2008 are introduced. The 2004 Niigataken-chuetsu earthquake caused failure of expressway embankments and uplift of sewage manholes. Liquefaction-induced damage to quay walls and tanks occurred in artificially reclaimed lands during the 2005 Fukuokaken-seiho-oki earthquake. Liquefiable area had been predicted about 17 years before the earthquake. Liquefied zones were fairly coincided with the predicted liquefiable zones. Very severe slide of highway embankments occurred at 11 sites during the 2007 Notohanto earthquake. During the 2007 Niigataken-chuetsu-oki earthquake, liquefaction induced in old river channels and on gentle slopes of sand dunes, and caused settlement of houses and breakage of low pressure gas pipes. However, some houses, sewage manholes, gas pipes were survived. Huge landslides and serious debris flows occurred along the slopes of Kurikoma Volcano during the 2008 Iwate-Miyagi-nairiku earthquake. Many landslides and debris flows occurred

Cyclic Strength of Undisturbed Mine Tailings

In order to update existing regulations for the seismic design of tailings retention dikes, extensive investigations were undertaken for 15 existing tailings dams throughout Japan. Undisturbed samples procured from the tailings disposal ponds were tested ln the laboratory to determine the cyclic strength of the in-situ tailings deposits. The results of cyclic triaxial tests on these materials are summarized by means of empirical formulae which are recommended for incorporation in the new seismic design code for the tailings dams

A Detailed Study on the Liquefaction-Induced Settlement of Timber Houses During the 2000 Tottoriken-Seibu Earthquake

More than 100 timber houses settled and tilted due to liquefaction at a housing development during the 2000 Tottoriken-seibu earthquake in Japan. Among the damaged houses, 47 houses tilted more than 15/1000. Heavily tilted houses were necessary to restore to become horizontal after the earthquake, though several houses, that tilted slightly, were not necessary to restore. The authors studied the boundary of the angle of the restored and non-restored houses. According to the study by the authors, the critical angle of tilting to restore houses was about 10/1000. The authors studied soil conditions also, and found that groundwater level was shallower than about 1.7 m in the damaged zone. This implies that small structures such as timber houses have no damage due to liquefaction if the groundwater level or the bottom of surface non-liquefiable layer is deeper that about 1.7 m

Shaking Table Tests on Permanent Ground Displacement Due to Liquefaction

To study the mechanism of permanent ground displacement due to liquefaction, shaking table tests were conducted. Moreover, vane tests and cyclic torsional shear tests were carried out to measure the rate of decrease of the elastic modulus and the shear strength due to liquefaction. Based on these test results, the authors proposed a simplified procedure for the prediction of permanent ground displacement. Measures to counter permanent ground displacement were also discussed based on the analysis

Liquefaction Induced Permanent Ground Displacement in Niigata City

Permanent ground displacement resulting from the 1964 Niigata Earthquake were studied based on pre- and post-earthquake aerial surveys. In the area along the Shinano River and the Tsusen River, extensive large ground displacements up to about 10 m occurred towards the river, though the ground was almost flat. To ascertain the mechanism of such large ground displacement, several detailed soil investigations were conducted. And it was clarified that the gradient of the ground surface, the gradient of the bottom of the liquefied layer and the thickness of the liquefied layer were main factors affecting to the such large ground displacement

Effective Stress Analysis for Evaluating the Effect of the Sand Compaction Pile Method During the 1995 Hyogoken-Nambu Earthquake

The effect of the sand compaction pile method as a countermeasure for liquefaction mainly consists of three factors: increase in the density, increase in the horizontal effective stress and stabilization of microstructure. Proper evaluation of the effect of improvement is important for estimating the seismic behavior of the ground improved by the sand compaction pile method. How to incorporate the effect and its factors into an analytical model was investigated by simulating the seismic behavior of the ground at two sites during the 1995 Hyogoken-Nambu earthquake with the effective stress analysis method “FLIP.” It was found that not only the increase in the density but also increase in the horizontal effective stress were important in explaining the effect of the sand compaction pile method. Moreover, a model taking account of both sand piles and the improved ground between them suggested a possibility of reproducing the behavior of improved ground under large ground motions more properly

Geotechnical Aspect of Damage In Adapazari City During the 1999 Kocaeli, Turkey, Earthquake

This report summerizes detailed investigation on the structural damage and its geotechnical condition in the Adapazaý City, Turkey, during the 1999 Kocaeli earthquake by the reconnaissance team of the Japanese Geotechnical Society. Damages to individual buildings were investigated along several streets in the downtown area. A little rough investigation was made almost all downtown area, in which damages were classified by its cause, i.e., inertia force or soil liquefaction. These investigations as well as hearing investigation and areal investigation by means of helicopters made clear the area where there was an island a few hundred years ago by which the name of Adapazarý i.e., ada (island) + pazarý (market), came from. In addition, the damage in the Adapazarý City is shown to be strongly affected by the ground condition because damage caused by liquefaciton was observed only outside the old island and areas where significant structural damage was observed were concentrated near the boundary between the old riverbed and island

Analyses of Liquefaction-Induced Deformation of Grounds and Structures by a Simple Method

The authors proposed a simple method to estimate liquefaction-induced deformation of grounds and structures. Adaptability of the method to the settlement of footings was studied. Centrifuge tests for the footing of transmission tower were selected to demonstrate the adaptability of the method. Analyses were carried out under the same conditions of the centrifuge tests. By comparing the analyzed results with the tested results, it was concluded that the effect of thickness of liquefied layer and soil density on the settlement of footing can be evaluated well by the simple method. Effect of countermeasures on the settlement of footing also could be evaluated well

Coronary artery bypass surgery with arterial grafts in familial hypercholesterolemia

AbstractObjective: Familial hypercholesterolemia is a dominantly inherited disorder caused by mutations at the locus for the low-density lipoprotein receptor and is frequently associated with premature coronary artery disease. This study was performed to determine whether arterial grafting was associated with long-term benefits for patients with familial hypercholesterolemia. Methods: During the past 18 years, 101 patients with heterozygous familial hypercholesterolemia underwent primary coronary artery bypass grafting, with one hospital death. Group 1 patients (n = 31) received only saphenous vein grafts. Group 2A patients (n = 47) received one internal thoracic artery graft and supplemental vein grafts, and group 2B patients (n = 23) had multiple arterial grafts. After operation, all patients received diet therapy and intensive cholesterol-lowering drug therapy. Thirteen patients received low-density lipoprotein apheresis. Results: During a mean follow-up period of 95 months, 8 patients died, 9 underwent reoperation, and 12 received catheter intervention. The overall survival was 82% (95% confidence limits, 65%-97%) at 18 years after operation. The survival in group 2 was higher than that found in group 1 (P = .01). The overall freedom from major cardiac events (myocardial infarction, cardiac death, reoperation, and catheter intervention) was 57% (95% confidence limits, 40%-74%) at 16 years after operation. The freedom from reoperation in group 2 was higher than that found in group 1 (P = .03). There was no difference in the survival or freedom from major cardiac events between groups 2A and 2B. Conclusion: Arterial grafting improved the long-term freedom from reoperation in patients with familial hypercholesterolemia. Additional benefit of multiple arterial grafting could not be identified. (J Thorac Cardiovasc Surg 2000;119:1008-14