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Based on a past centrifugal model test and complementary discrete element method (DEM) simulation, this paper provides insights into bearing resistance of diameter-expanded anchorage with its anchor body expanded. In the centrifugal model test, an anchor body model set at a depth of 100 mm and a diameter of 27 mm in sand was pulled horizontally in a centrifugal acceleration of 30 G. The behaviour of the model ground during pulling was portrayed through the DEM modelling. Spherical particle and non-spherical particle composed of two spherical particles connected rigidly were used as analogues of soil particles in the simulation. The simulation result of spherical particle with inter-particle friction coefficient of 0.5 was similar to the ground deformation and the pull-out resistance obtained from the experiment.

In this study, an inclined model experiment and finite element analyses were conducted to evaluate the failure mode and seismic response of a dry-type large-scale concrete-block retaining wall (LCBW). In the experiment, the objective was to reproduce the sliding between concrete blocks that was observed in past cases LCBW damage in order to characterise the behaviour until failure. A numerical simulation corresponding to the experimental conditions was conducted by the finite element method (FEM). Dynamic analyses were also performed by FEM to investigate the seismic response of the concrete blocks under various ground conditions. The experimental results revealed that slip between the concrete blocks caused brittle failure of the LCBW. In the FEM simulation, the joint elements reproduced the experimentally observed sliding between the concrete blocks. A dynamic simulation of the full-scale model revealed that significant sliding and rocking of the concrete block occur in a dry-type LCBW. These findings indicate that stress concentration may occur at the heels of the concrete blocks during an earthquake.

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 construction (EOC). Predicted unfactored maximum reinforcement tensile loads at the EOC using four different load models were judged to be conservative (safe for design) based on comparison with measured loads for both walls. Reinforcement loads were observed to increase with decreasing toe support, particularly at the base of the walls. A fully developed composite soil failure mechanism propagating from the heel of the foundation bulkhead and behind the reinforcement layers was observed during excavation of the stepped base wall model. There were no visual indications of soil failure within or behind the wall with longer uniform reinforcement lengths. However, predicted EOC loads for this wall were exceeded for most layers after loss of toe support. Implications for the design, analysis and performance of steel strip reinforced soil walls with similar reinforcement arrangements constructed over initially competent soil foundations and then subject to loss of toe support are identified.

ABSTRACT: This paper reports the results of three 4 m high full-scale instrumented geogrid-reinforced soil walls constructed with different structural facings having a range of stiffness. The walls were seated on a 2 m deep foundation layer that was laterally supported at the base of the wall face by a rigid bulkhead. Following end of construction, the bulkhead was moved outward in stages to simulate loss of foundation support in the vicinity of the wall toe. Bulkhead loads, wall deformations, backfill settlements, reinforcement loads and earth pressures recorded at end of construction and during bulkhead displacement are presented in this paper. Measured reinforcement loads are compared to predicted loads at end of construction using different design methods. The walls demonstrated that there was available reserve load capacity which prevented internal failure mechanisms from developing in the reinforced soil zone even after significant loss of foundation support in the vicinity of the wall toe. At the end of each test the reinforcement layers were shortened in stages by cutting using nichrome heating wires. For the most flexible wall in this programme, the shortening of the reinforcement triggered a composite soil failure mechanism extending from the base of the foundation zone to the surface of the soil backfill. Implications of the analysis results and other observations on wall performance and design are discussed.

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 three different granular soils varying with respect to permeability, fines content and shear strength. Earth pressures and reinforcement loads were recorded at end of construction and at the end of each flooding cycle prior to draining. Hence, for the purposes of analysis, the walls were treated as either in a drained or flooded steady state condition. In-situ steel strip pullout tests were also performed. The wall facings were very permeable and thus prevented unbalanced hydrostatic and seepage forces from developing during drawdown that could increase reinforcement strip loads beyond drained condition values. The effects of soil type on measured loads at the connections and peak tensile loads located within the reinforced soil zone are identified. Measured reinforcement tensile loads at end of construction and at the end of peak flood stages are compared to predictions using different analytical models for the (dry) EOC condition. Similar comparisons are made using measured pullout test results and predictions using different pullout models. Implications for current design practice and wall performance in transient flooding environments are reported.

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 and at time of foundation failure below the footing were greater for the wall with the shorter reinforcement lengths. Reinforcement loads at end of construction were best estimated using a working stress model proposed by the authors rather than current methods used in Japan and the UK. However, after significant loss of footing support, the Japanese Public Works Research Centre method gave more accurate and safer load predictions. Regardless, both the anchor rods and anchor plates had abundant reserve capacity to provide large margins of safety against internal tensile rupture and pullout modes of failure even after large foundation displacements.

In this study, a series of inclined model experiments were conducted to investigate the behaviour of reinforced soil walls with leakage of backfill material. The experimental results were simulated by discrete element method (DEM). From the results of the inclined model experiments, it was confirmed that the tensile force in the reinforcement near the wall facing decreased due to the leakage of the backfill material, while decreasing the horizontal resistance of the reinforced soil wall remarkably. The leakage behaviour observed in the experiment was simulated using DEM. From the results of the DEM simulation, the calculated displacement pattern was found to be roughly similar to that obtained in the experiment. During leakage of the backfill material, an area without normal contact forces was generated at the lower end and this area developed toward the upper side. Such a change in normal contact forces affects the behaviour of a geogrid, in particular the disappearance of normal contact forces weakens the interlocking between the geogrid and the soil. This observation agrees with the experimental finding that the strain of the geogrid decreased in the area near the back of the wall facing.

Transgenic rice (Oryza sativa L., a C3 plant) lines carrying a complete phosphoenolpyruvate carboxylase (PEPC) gene from maize (a C4 plant) were tested for their performance in terms of organic acid synthesis and organic acid exudation into the rhizosphere under phosphorus (P)-deficient conditions. High PEPC activity increased the fraction of photosynthetically fixed carbon allocated to the organic acid pool, and P deficiency enhanced oxalate exudation from the roots of the transgenic plants. There was no evidence that the transformed PEPC was involved in internal P recycling in the plant. However, the root PEPC activity was positively correlated with the oxalate exudation and negatively correlated with the root P concentration, and a higher root PEPC activity led to a higher oxalate exudation. Thus, it is suggested that C4-PEPC transgenic rice plants had acquired the ability to exude oxalate, which enhanced their capacity to adapt to low P soil conditions.

It has already been shown that the stability of the geotextile reiforced earth walls was improved with the use of rigid facings that brought about the reduction of overall deformation and the amount of tensile force generated in geotextile. To evaluate the effects of facing rigidity, stress-deformation behavior must be analyzed based on the interaction of facings, geotextiles, and soils.A numerical analysis using a two-dimensional elasto-plastic FEM taken account of the construction process was conducted to clarify various aspects of the behavior of a reinforced earth walls measuring 10.0m high. Three types of facings were analyzed: the wrapped-around wall face method, the concrete panel face method, the concrete block face method. In addition, the slope of wall was varied from 1:0.0 to 1:0.8 (pitch of 0.2). The results showed that facings performed using the block and panel face method, which provided higher rigidity than the wrapped-around wall face method, could be increased the stability of the reinforced earth walls under the characteristic bound coditions be satisfied

A 65-year-old woman was admitted to hospital because of orthopnea. She had been followed-up for chronic pericardial effusion detected by echocardiography 10 years previously. Initial echocardiography showed that the left ventricular diastolic diameter (LVDd) was 39 mm and percent fractional shortening (%FS) was 33.3%. Neither fluid samples nor a pericardial biopsy specimen identified the etiology. Cardiac tamponade was not evident, and C-reactive protein and creatine-kinase values were within normal limits. During follow-up, the %FS decreased gradually, but the LVDd remained unchanged. On admission, echocardiography showed that the %FS was 12.5% and LVDd was 40 mm. She developed intractable hyponatremic heart failure with bilateral pleural effusion. Autopsy findings revealed that infiltration of small lymphocytes in the epicardium had penetrated into the subepicardial myocardium. The subepicardial myocardium and the interventricular septal myocardium were diffusely replaced by fibrosis, which could have induced restrictive diastolic heart failure and reduced left ventricular contractility. The fibrosis was not detected in the epicardium itself nor the subendocardial myocardium. This is the first report describing diffuse subepicardial myocardial fibrosis in a patient with chronic pericardial effusion and progressive heart failure.

We partially purified three Nicotiana tabacum L. embryogenic pollen-abundant phosphoproteins (NtEPa to c) which appeared in the cells undergoing a dedifferentiation process from immature pollen grains to embryogenic cells, caused by glutamine-deficiency in vitro. All the NtEPs had a highly conserved N-terminal amino acid sequence. Using degenerate oligonucleotide probes designed from the amino acid sequences, the cDNA for NtEPc was isolated from a cDNA library of pollen cultured in glutamine-free medium The cDNA sequence showed moderate homology with several type-1 copper-binding glycoproteins and with a kind of early nodulin though its function could not be predicted. Expression analysis revealed that the level of mRNA for NtEPc was high during the dedifferentiation and also in the very early period of pollen embryogenesis but it was low in the developmental process of microspores/pollen in anthers, in the in vitro maturation process and both in the stational and logarithmic growth phases of tobacco BY-2 cells. Furthermore, an acidic medium pH, which promoted the induction of dedifferentiation increased the level of mRNA for NtEPc, whereas the presence of 6-benzylaminopurine, which inhibited it, decreased the level. These results suggest that the expression of NtEPc gene is correlated with the dedifferentiation but not with pollen development or cell division.