This paper outlines a mathematical description of the stress dilatancy behaviour of granular materials which accounts for stress level and void ratio dependencies. The consideration of these aspects has important implications in the modelling of granular material behaviour. In fact, granular material mechanical response is largely dominated by the evolution of dilatancy, fabric and void ratio histories. The starting point in this study is the well established Rowe's theory which is revisited and ultimately modified by introducing a factor linked to governing state parameters in order to describe the complete behaviour of granular materials during deformation. Numerical simulations of triaxial tests on granular materials at different void ratios and stress levels are herein presented to illustrate the model.

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The design implication of stress-confinement effect of nonwoven geotextile is addressed. The unconfined and confined strengths of a selected needle-punched nonwoven geotextile are used to conduct a comparative design of a granular soil retaining wall based on a limit equilibrium approach. A higher wall may be allowed when considering the confined strength as compared to the unconfined strength. For a selected wall height, confined strength allows for fewer geotextile layers when compared to that designed using unconfined strength. It is recommended that stress-confinement test procedure should be standardized so that confinement effect of some nonwoven geotextiles may be incorporated into an individual wall design procedure.

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The main objective of this paper is to compare safety factors obtained from Morgenstern-Price, Janbu and Spencer methods with the factors calculated from the modified variational approach (Leshchinsky and Huang, 1992a). Such comparison is essential since there is no mathematical proof that the variational analysis indeed yields a minimum and thus, physically produce significant results. The safety factors compared well, indicating the variational analysis is on a par with acceptable existing rigorous methods. Availability of a user-friendly computer code may make the variational analysis useful to practicing engineers. However, its greatest potential at the moment is in 3-D applications; i.., unlike other methods, its extension to 3-D is straightforward.

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A procedure for limit equilibrium slope analysis based on a realistic consideration of the mobilized interslice shear forces is presented in this paper. This new approach ensures that solutions are kinematically admissible and the possibility of convergence problems, often associated with numerical solutions, is minimized. The proposed approach recognizes the importance of slip surface geometry in estimating interslice shear forces whether vertical or non-vertical slices are used in a limit equilibrium analysis. Illustrative examples are presented and the results shown to be reasonable. The calculated factors of safety based on the new method compare very well with values based on recognized methods of analysis. Yet the method is more direct and enables a proper visualization of the transfer of mobilized normal and shear forces through a sloping soil mass above a potential slip surface. The method also gives consistent results with non-vertical slices even if the shape of non-vertical slices is varied.

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It has been shown after mathematical and mechanical investigation that Limit Equilibrium Method (LEM) can be considered as a method to obtain the necessary condition of Slip Line Method (SLM), and that the solution can be obtained under the condition that F_s=1 and ∂F_s/∂θ=O, where F_s is the safety factor and θ is the inclination of the plane on which the safety factor is defined. Next, the generalized LEM (GLEM) is proposed, dealing with the following points : (1) Triangular or quadrangular blocks can be treated; (2) Safety factors are defined also on interblock planes; and (3) All types of plastic problems, slope stability, bearing capacity, and earth pressure are identically formulated. Two situations regarding treatment of the moment equilibrium condition are discussed. GLEM is applied to well-known problems. The results agree well with those obtained by theoretical methods. GLEM can be used to obtain the distribution of earth pressure or bearing capacity. GLEM, Iike ordinary LEM, is very effective for the practical problems, but GLEM is more theoretical and it can result in more accurate solutions.

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Two new partially saturated tricyclic ring systems, , a, 7, 8, , 10, 10a, 11-octahydro-11-oxodibenz [, ] oxepins (3a and 3), and -thiepins (4a and 4) were synthesized. Compounds 4a and 4 were desulfurized to give a pair of isomeric 2-methylbenzoylcyclohexanes (10a and 10). Deuterated 4a and 4 (11a and 11) were prepared starting from butadiene- (12). The stereochemical features of 3a (trans), 3 (cis), 4a (trans) and 4 (cis) are compared with those of 10a, 10, 11a and 11 on the basis of proton nuclear magnetic resonance data.

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This paper presents the results of 24 centrifuge model tests of nailed soil slopes and vertical walls, constructed out of dry Leighton buzzard sand. The walls were initially supported by fluid pressure from flexible rubber bags against the face, and excavation was modelled by gradually draining the fluid from the bags. The finished model walls were 200 mm high and were initially tested at 30 g acceleration to correspond to a prototype structure . m high. If failure was not obtained, the acceleration was increased progressively to a maximum of 80 g. No surcharges were applied. The main parameters varied in the tests were the wall slope, nail length, nail surface roughness, nail inclination, facing stiffness and facing roughness. Observations were made of the mechanism of failure when it occurred, of soil pressures on the facing, and of pre-failure deformations. Failure was always by pull-out rather than breakage of the nails, and a series of pull-out tests of the model nails was conducted to aid interpretation of the results. Failure surfaces were seen to have the shape of logarithmic spirals, and limit equilibrium analyses based on these surfaces agreed well with experimental observations. Prior to failure, earth pressures on the facing compared reasonably well with those calculated by Coulomb's method, except at the base of the wall. One test set out to model a full-scale trial wall, and although the construction process could not be exactly modelled in the small-scale centrifuge tests, comparisons were sufficiently good to give confidence in the model test results.

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This paper deals with the overall stability of an embankment foundation failure that lies at km 40+700 of the new Irbid-Amman Highway in Jordan. Slope stability back analysis was carried out for the slope to assess the conditions at time of failure, and estimate most representative shear strength parameters of foundation materials. Slope stability analysis was also carried out for proposed remedies. Probabilistic seismic hazard analysis was carried out for the landslide site. Peak Ground Acceleration (PGA) value of .2 g was estimated for design. This corresponds to a 90% probability of non-exceedence in a 50 year design life of the highway. Pseudo-static slope stability analysis was also carried out. The study concluded that the landslide movement occurred within the foundation colluvium material. It resulted primarily from the excessive load of the embankment and excess piezometric pressures generated within the slope. The most feasible remedial measure to stabilize the landslide area was removal of existing failed embankment down to the top of sandstone layer, and reconstruction (using imported free-drainage rockfill) of a split level embankment together with the construction of surface and subsurface drainage system. These measures were successfully implemented in the field.

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To remove some weak points of the limit equilibrium slope stability method, the authors have tried so far to develop a hybrid slope stability analysis method, in which stress and strain developed in a slope are determined by the finite element method, while the basic concept of the limit equilibrium method is adopted in the overall stability analysis. In this paper, first, the theory behind the hybrid slope stability analysis method is presented, together with the comparison of the proposed hybrid method and the conventional Bishop's method. Then, reinforcement mechanism and stability characteristics of the reinforced slope cutting are examined through numerical examples by the proposed method. Finally, practical application of the proposed method to an in-situ reinforcement slope stabilization project is presented. In consequence, the applicability and simplicity of the proposed method to the practical design works of reinforcement slope stabilization are demonstrated in success.

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A new analytical method is proposed for determining the inextensible grid reinforcement pullout resistance and pullout force/pullout displacement curve by using basic backfill soil and grid reinforcement properties. The pullout skin friction resistance/pullout displacement relationship is simulated by linear elastic-perfectly plastic model. A hyperbolic model has been proposed to represent the pullout bearing resistance/pullout displacement relationship in which the maximum bearing resistance of a single bearing member is determined using a new bearing capacity equation proposed in this paper. The influences of the grid bearing member spacing ratio, S/D, the bearing member deflection rigidity, and the pullout softening behavior on the mobilization of pullout bearing resistance are explicitly included in the proposed model. Good agreement has been obtained between calculated values and laboratory test results.

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The advantages and disadvantages of using a back analysis of slope failures to evaluate soil shear strength are discussed. A methodology is presented herein that allows the implied level of reliability associated with soil shear strength parameters back calculated from slope failures to be estimated. A reliability approach is also used to estimate the probability of failure for a given limit equilibrium slope stability method, design factor of safety, and combination of back calculated Mohr-Coulomb shear strength parameters, ' and φ'. The methodology is illustrated using 39 landslides in the Orinda Formation in the San Francisco Bay area. The impact of additional case histories in the same geologic setting, i.., a larger data set, on the required design factor of safety for a given probability of failure is also investigated.

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11-Amino-, a, 7, 8, , 10, 10a, 11-octahydrodibebenzo[, ]thiepines (a-d) and -oxepines (7a-d) were synthesized by the Leuckart reaction of , a, 7, 8, , 10, 10a, 11-octahydro-11-oxodibenzo[, ]thiepines (1a, )and -oxepines (2a, ) followed by hydrolysis of the reaction products 4a-d and a-d, respectively. The four diastereomers, cis(a-H, 10a-H)-cis(10a-H, 11-H) a and 7a, cis(a-H, 10a-H)-trans(10a-H, 11-H) and 7, trans(a-H, 10a-H)-trans(10a-H, 11a-H) and 7, and trans(a-H, 10a-H)-cis(10a-H, 11-H) d and 7d, were isolated and their configurations and conformations were elucidated by chemical methods together with ¹H-nuclear magnetic resonance spectroscopic and X-ray crystallographic analyses.

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