Lateral Loading Tests in The Pit for a Large-Diameter Deep Pile

Although the ground supporting the foundation can be regarded as three-dimensional nonlinear continuous body, in design, grounds are modeled as linear elastic springs. However, in reality, grounds exhibit nonlinear load-displacement (ρ-δ) characteristics. In Specifications for Highway Bridges (Japan Road Association, 1994), ground reaction coefficient is defined as the secant slope of noticeable displacement and load intensity on ρ-δ curve corrected according to width of foundation. For the purpose of examining the scale effect of large-diameter pile, this paper presents a study on scale effect of lateral ground reaction coefficient based on results of lateral loading tests performed using large loading plate in the pit of a large-diameter deep pile

Case Studies on Long-term Settlement of Soft Clay Ground

Two case histories on long-term settlements of Ariake clay which is counted as one of the soft clays in Japan are described. The one of them is to report the settlement which have been observed over 25 years since construction of embankment for breakwater on the coastal Ariake deposit. The another case history is concerned with the settlement of low embankment highway on Ariake clay whose shallow surface was improved by quickline-clay mixture as a countermeasure for the settlement. The current paper is featured by the fact that the predominant secondary settlement is common with two case histories. The finite element method using an elasto-plastic mo1el was adopted to analyze the settlement of the Ariake clay observed in the above-mentioned two case histories under sustained and transient loading, respectively. It is concluded from comparison of analytical results with observed settlement that the proposed model with consideration of secondary compression is advantageous for long-term settlement prediction of soft clay

Settlement Prediction of Soft Clay Ground under Sustained and Transient Loading

Two case studies of settlement prediction of Ariake clay ground which is counted as one of the soft clays in Japan are described. The one of them is to report a long-term settlement which have been observed over 25 years since construction of embankment for breakwater on the coastal Ariake deposit. The another case study is concerned with the settlement of low embankment highway on Ariake clay whose shallow surface was improved by quicklime-clay mixture as a countermeasure for the settlement. It is featured by the fact that the predominant secondary settlement is common with two case studies. The finite element method using an elasto-plastic model was adopted to analyze the settlement of Ariake clay observed in above-mentioned two case studies under sustained and transient loading, respectively. It is concluded from comparison of analytieal results with observed settlement that the proposed model with consideration of secondary compression is advantageous for settlement prediction of soft clay ground

Memory impairment caused by cerebral hematoma in the left medial temporal lobe due to ruptured posterior cerebral artery aneurysm

BACKGROUND: Cognitive disorders, such as memory disturbances, are often observed following a subarachnoid hemorrhage. We present a very rare case where rupture of a posterior cerebral artery aneurysm caused restricted damage to the hippocampus unilaterally, and caused memory disturbances. CASE PRESENTATION: A 56-year-old, right-handed man, with a formal education history of 16 years and company employees was admitted to our hospital because of a consciousness disturbance. He was diagnosed as having a subarachnoid hemorrhage due to a left posterior cerebral artery dissecting aneurysm, and coil embolization was performed. Subsequently, he had neither motor paresis nor sensory disturbances, but he showed disorientation, and both retrograde and anterograde amnesia. Although immediate recall and remote memory were almost intact, his recent memory was moderately impaired. Both verbal and non-verbal memories were impaired. Brain computed tomography (CT) and magnetic resonance imaging (MRI) revealed a cerebral hematoma in the left temporal lobe involving the hippocampus and parahippocampal gyrus, and single-photon emission computed tomography (SPECT) demonstrated low perfusion areas in the left medial temporal lobe. CONCLUSIONS: We suggest that the memory impairment was caused by local tissue destruction of Papez’s circuit in the dominant hemisphere due to the cerebral hematoma

STRESS CONDITIONS WITHIN SIMPLE SHEAR TEST SPECIMEN

On the basis of the assumption that the stresses within the simple shear test specimen are completely uniform, the two methods for interpreting the stresses within the specimen are described. The first method consists in assuming that the simple shear stress conditions are represented by the pure shear stress conditions. The second method is based on the assumption that the directions of the principal stress axes during simple shear are known. The differences between the two methods are discussed, and the undrained shear strength values of normally consolidated clays measured in the simple shear test are compared with those measured in the triaxial compression test on an equal basis

UNDRAINED STRENGTH OF NORMALLY CONSOLIDATED CLAY MEASURED IN THE SIMPLE SHEAR TEST

This paper discusses a method for calculating the "true" undrained strength ratio, (cu/p)ss, and the internal friction angle, φ\u27ss, in terms of effective stress of normally consolidated clays measured in a simple shear test. The proposed method consists in assuming that the directions of the principal stress axes during the simple shear test are expressed by the relation proposed by Oda and Konishi. Experimental results obtained from three types of clays confirm that the method gives more reasonable estimates of (cu/p)ss and φ\u27ss for normally consolidated clay compared to other methods. The method also supports Ladd\u27s statement that (cu/p)ss should generally be less than (cu/p)TC determined from the triaxial compression test due to undrained strength anisotropy. Finally, a significant disadvantage of the method proposed by Duncan and Dunlop is discussed, and it is pointed out that the Duncan and Dunlop method may predict excessively high values of φ\u27ss for normally consolidated clay

Deformation and Strength of Anisotropic Sand Under Three Dimensional Stress Conditions

The three-dimensional, drained stress-strain and strength behavior of a sand prepared in cubical specimens with cross-anisotropic fabric was studied using triaxial compression, plane strain, and cubical triaxial tests with independent control of the three principal stresses. All specimens were loaded under conditions of principal stress directions fixed and aligned with the directions of the material axes. For comparable test conditions, the major principal strain was smallest and the rate of dilation was highest when the major principal stress acted perpendicular to the long axes of the sand grains. The opposite extremes were obtained when the major principal stress acted parallel to the long grain axes. The effects of initial cross-anisotropic fabric were mainly observed in the prefailure stress-strain behavior, whereas sufficient changes in the fabric had occurred at large strains to produce failure conditions which resembled those observed for isotropic sands. The three-dimensional failure surface could for practical purposes be modeled by an isotropic failure criterion