In the frame of the continuous damage theory, a damage model for soil-cement mixture is proposed using the unified form with one set of parameters, based on experimental observations. The suggested model can reflect its main mechanical properties : as the confining pressure increases, the strength and strain at peak stress increase remarkably and the stress-strain relations change from strain-softening to strain-hardening while the volumetric strain changes from dilatation to contraction. All the parameters can be calibrated by a group of conventional triaxial tests. Hollow cylinder tests with complicated stress states were conducted to verify the damage model. The results predicted by the damage model agree well with the tests, which implies that the damage model can be applied to complicated stress states.

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Anchor has been successively used as an in-situ soil reinforcement for more than two decades. The design of anchors is traditionally performed based only on its pull-out capacity, which ignores the interface interaction between anchor and soil due to relative displacement. This paper provides the analytical solutions based on the linear elastic-perfectly plastic model for the interface between the anchor and soil. The derived analytical solutions include the case of soil movements along the anchor axis and the case of soil movements normal to the anchor axis. It shows that the anchor pull-out behavior is only a special case of the general solution for the anchor subjected to the soil movement along its axis. The parametric study for both actively loaded and passively loaded anchor has been extensively carried out, which provides insights into the interface interaction between the anchor and soil and general guidelines in design of an anchor system.

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Combining the conventional method of slices for slope stability analysis with the previously derived analytical solutions for the anchor-soil interaction, a displacement-based approach for the stability analysis of anchor reinforced slope has been developed. The procedure for evaluating the working forces in the anchor, the global factor of safety, and the limits of the anchor working force is described in detail. Furthermore, the effects of reinforcement on the slope stability due to different parameters, such as soil properties, anchor characteristics and anchor-soil interface properties were studied. The numerical results demonstrate the progressively mobilized anchor forces and their distribution along a vertical section of the slope, and the expected global factor of safety at each stage of soil movement along the slip surface. Also, for a given anchor reinforced slope, the anchor working limit is generated along a vertical section of the slope, which controls the anchor resistance to the slope and limits the potential soil movement. Based on the results of the analysis, the general guideline for the design of an anchor reinforced slope is discussed.

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An equivalent continuous model considering the heterogeneity of anisotropic parameter distribution is developed to estimate flow and transport problems through fractured rocks. To examine the validity of the model, tracer tests at different two sites, Aspo Hard Rock Laboratory and Finnsjon test site in Sweden are simulated and the calculated results are compared with the observed ones. The model is made systematically using the in-situ investigation results. In particular, a method for inferring the fracture length and probability distribution function is newly proposed. Moreover, the representative elementary volume is examined by the model in order to avoid the size dependency of the finite element analyses. The phenomena are considered as a random process and many realizations are examined. It becomes clear that this method can give fairly good predictions for different boundary conditions and different measuring points.

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A site investigation campaign using cone penetration test (CPT) and dilatometer test (DMT) was carried out on three sandy soils of Japan. Two of these sites are natural sand deposits and the third one is a sand fill reclaimed about twenty years ago. On two sites, high quality samples were taken using the freezing sampling method so that the measured value of the relative density D_r is assumed to be accurate. Seismic cone tests were also performed in order to measure the shear modulus at a very small strain level in the order of 10^-5. Data from CPT and DMT were related to design parameters using correlations established from calibration chamber tests. The main conclusions obtained in the present study are : 1) existing soil classification methods using CPT and DMT data can be applied to the investigated sites ; 2) D_r values predicted from relationships linking D_r to q_t/(p'_v0)^0.5, where q_t is the point resistance from CPT and p'_v0 is the vertical effective overburden pressure, seem to be in good agreement with actual values of D_r ; 3) D_r can also be well predicted using DMT horizontal stress index K_D values, and 4) the ratios of the shear modulus G_sc from the seismic cone to q_t or E_D from DMT, G_sc/q_t or G_sc/E_D decrease with increasing values of the relative density D_r.

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The primary objective of this paper is to evaluate the potential use of Jordanian oil shale ash as a soil stabilization agent. Three types of soil were used in this study along with three percentages of oil shale : 5%, 10% and 15% by dry weight of the soil. Swelling pressure tests and unconfined compression tests were conducted on remoulded samples mixed with a predetermined percentage of the oil shale ash at different curing times. It was found that higher percentages of the shale ash increase the unconfined compressive strength and minimize the swelling pressure of the soil. Furthermore, the test results indicate that the optimum time for the stabilization of soil mixed with oil shale ash occurs at seven days.

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A series of shaking table tests are made to investigate the uplift behavior of sewer pipes caused by liquefaction of surrounding soil. It is shown that uplift displacement of pipes buried in unliquefiable original soil, which does not allow a dissipation of excess pore water pressure from liquefied backfill soil, increases drastically when they are subjected to extensive shaking. Uplift displacement of pipes buried in liquefiable original soil, on the other hand, accumulates rather gradually even at moderate shaking. A different behavior on residual deformation of the backfill and the original soils is also observed. In relation to the effects of soil condition, damage to sewer pipes in Towada City caused by the December 28, 1994 Sanriku-Haruka-Oki earthquake is reported and discussed. It is estimated that upper backfill soil consisting of sandy gravel may have liquefied because it was under loose and saturated condition and was subjected to earthquake motion under nearly undrained condition due partly to its own low permeability and also to the existence of surrounding original soil with low permeability.

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Leakage of water due to internal erosion through a dam body or foundation is a major problem with fill-type dams. Recent case histories and research suggest that most cases of internal erosion are possibly triggered by hydraulic fracturing. However, the quantitative mechanism of hydraulic fracturing still remains to be solved. Therefore in-situ hydraulic fracture tests were carried out with a cheap, concise apparatus using boreholes dug in the soft clayey volcanic soil foundation of a low earth dam (Oyachi Dam) in Niigata Prefecture. Water was injected into the foundation through a perforated pipe by two methods : one was under a controlled injection pressure and the other was a controlled injection flow rate. In the former method, the relationship between flow rate and injection pressure was observed and it was found that a yield pressure or fracture pressure existed in all the tests. By repeating the injection test it was confirmed that once a crack is developed, it is very easily reopened by a water pressure a little higher than the earth pressure exerted on the crack. In the latter method, the relationship between injection pressure and time was observed and it was found that fracture pressure varied with flow rate. The boreholes were excavated to observe the development of fracture cracks and it was also found that the cracks had developed perpendicular to the borehole periphery, which means that fracture cracks were induced by tensile stress and denies the explanation that fractures are caused by shear failure.

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Lateral internal earth pressure during landslide movement was observed in-situ at two-minute intervals. The data obtained are discussed together with other observational data for the landslide. Findings for actual landslide motion in three distinct events are summarized as follows : variation in the observed earth pressure differed with the borehole position. Variation at the onset of movement was measured in a limited number of boreholes. Large variation appeared after a certain amount of relative displacement occurred at the slip surface. There was a rapid increase in earth pressure in almost all the boreholes at the moment movement stopped. Anisotropic stresses in earth pressure that accumulated during movement were released when it stopped, and the difference in pressure before and after the sliding was small. An almost constant peak earth pressure, designated the passive earth pressure, was found in a borehole during the three events.

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A new approach to soil stabilization is presented in this study using two newly introduced materials, artificially manufactured albumin and eggshell powder (E.S.P.). Albumin, which was used a long time ago in some middle east countries as a water-proofing agent (prime coat) under painting, and in Japan as a main component of the mortar in building masonry-arch bridges, is used here in an attempt to improve and stabilize the problematic Shirasu. Eggshell powder was tried also in the hope of some similarity to albumin. Shirasu was mixed with 1.0%, 1.50% and 2.0% of albumin and with 5.0%, 10.0% and 15.0% of eggshell powder based on its dry weight and then compacted to a constant density before being oven dried at different temperatures. Direct shear tests, unconfined compression tests, slaking tests and permeability tests were performed. All tests produced very good results, especially in raising the shear strength and the unconfined compressive strength, with albumin ; they did not give the desired results with eggshell powder.

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A stress-strain-dilatancy model for sand that centers on the idea of integral modelling over the relevant density and normal stress states is presented. The model is built within the framework of the state concept, in which a relative initial state with respect to some reference states of sand (critical or steady state ; quasi steady state) is used for characterization of sand behaviour. The state index I_s, which is a direct measure for the relative initial state, is used to quantify the combined influence of the density and normal stress on the stress-strain curve. Results of a series of drained p-constant torsional tests on sand samples with various initial states were used to examine and establish a rational relationship between the stress-strain parameters and the state index. It is demonstrated that there is a clear link between the relative initial state (the state index I_s) and the normalized p-constant stress-strain curve of sand, and that there exists a linear correlation between I_s and the parameters of a modified hyperbolic stress-strain relation. These stress-strain parameters are shown to accurately simulate sand behaviour over a wide range of densities and confining stresses. The implication of the state index as a current variable is illustrated in the case of monotonic undrained loading. Characteristic features of the model with respect to the combined influence of density and mean normal stress are discussed through a comparison with conventional sand modelling.

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Dynamic soil properties around axially vibrating piles are generally non-uniform even in homogeneous soils. This is a result of the non-linear soil reaction to the radially decreasing stresses and strains induced by the pile, as well as the slippage at the pile-soil interface. To improve the accuracy of analytical computations, this paper focusses upon the nonlinear soil response anticipated in the field and establishes the radial variation of soil properties based on commonly reported experimental data. In addition, solutions are presented for the corresponding impedance of the springs and dashpots used to represent soil in a Winkler-type analysis of axially vibrating piles. Slippage at the pile soil interface is taken into account assuming a rigid-perfectly plastic contact between the pile and the soil. To assess the relative effects of soil nonlinearity in practical applications, analytical results for different pile, load and soil conditions are presented in the form of diagrams and simple approximate relationships.

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An experimental investigation was carried out to study the feasibility of using fly ash, the industrial residue of thermo-electric power plants, as a fill material for waterfront retaining structures. In the study, centrifuge model tests were performed on cement stabilized fly ash ground to investigate its failure pattern and active earth pressure acting on the retaining wall. The stabilized fly ash ground was brought to an acceleration field of 70g and then the retaining wall was allowed to rotate about its bottom to cause ground failure. As a result of this study it was found that the failure pattern of fly ash ground mixed with a small amount of cement is characterized by a vertical tension crack and a straight shear failure which is much different from those of ordinary clay or sandy ground. It was also found that the active earth pressure of the cement stabilized fly ash ground was lower than ordinary sand fill and could be reasonably estimated by a proposed method incorporating the failure pattern of the ground.

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This paper deals with the evaluation of the bearing capacity of a rectangular shallow foundation located near a slope or an excavation, by means of the yield design theory. Taking into account the true three dimensional nature of the problem, two types of failure mechanisms are selected, resulting in optimal upper bound estimates for the ultimate load bearing capacity of the foundation obtained through the implementation of the kinematic approach from outside. A computational tool is thus developed based on this approach, making it possible, for instance, to provide a quantitative assessment of the bearing capacity reduction due to the slope proximity. Such theoretical estimates are finally compared with experimental values obtained on full scale and centrifuge-reduced scale models.

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A simplified prediction method based on Terzaghi's bearing capacity formula for surface footing, with regard to size effects, is proposed. Clarification of size effects, which is indispensable for appropriate design of large foundations, may permit use of the results of small scaled loading tests and prevent increases in the construction costs of foundations. Size effects may be mainly attributed to stress-level effects on the shear strength of ground materials ; stress-level effects are taken into account in the proposed method. The proposed method incorporates a method for determination of shear strength constants c and φ that should be applied to the bearing capacity formula. A nonlinear Finite Element Method which incorporates the confining stress dependent shear strength is used to calculate stress distribution in foundation grounds beneath the footings. It is shown that the effective mean principal stress σ_m tends to range from 2γB to 10γB for strip footings and from 1γB to 15γB for circular footings ; within this region the parameters c and φ are determined from the straight fitting line. The proposed method is verified with the results of some series of model surface footing loading tests on cohesionless and cohesive grounds reported by the authors and other researchers. This verification confirms the applicability of the proposed method to strip, circular and square footings on cohesive and cohesionless foundation grounds with sufficient accuracy for practical purposes.

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Undrained monotonic loading triaxial compression and extension tests were conducted on Toyoura sand. It was found that the shear behavior was more contractive and softer in triaxial extension than in triaxial compression. This difference suggests that the stress conditions, such as the direction of the principal stress and the magnitude of the intermediate principal stress have some effects on the undrained behavior of sand. To clarify these effects, a series of tests was performed by means of an automated hollow cylindrical torsional shear apparatus. Dry-deposited Toyoura sand was used in these tests. The angle of the maximum principal stress from the vertical to the bedding plane, α, and the intermediate principal stress coefficient, b, were fixed in each test. The intermediate principal stress was fixed to horizontal. For any density, tests with a larger α-value, namely, a larger inclination of σ₁ from the vertical, and a larger intermediate principal stress coefficient b were shown to generate greater excess pore water pressure. In addition, the undrained simple shear behavior of sand under initial isotropic and anisotropic stress conditions was studied. It was made clear that triaxial compression (α=0°, b=0) gives the highest resistance with lowest contractancy, while triaxial extension (α=90°, b=1) gives the opposite extreme in the assessment of flow failure. Simple shear mode of deformation was shown to exhibit an intermediate stress-strain behavior between triaxial compression and extension, which is closer to most of the field conditions.

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In order to quantify the tendency to flow characteristics of sandy soils, the maximum value of excess pore water pressure ratio developed during undrained monotonic loading test was taken as an index property and defined as flow potential. Triaxial compression tests, triaxial extension tests and simple shear tests on Toyoura sand were conducted by means of conventional triaxial and hollow cylinder torsion shear apparatuses. As a result, it became clear that the flow potential of sand was greatly affected by shearing mode. Sand at the same density showed the lowest flow potential in triaxial compression and the highest in triaxial extension, while simple shear condition exhibited intermediate behavior. Flow potential was related to residual strength ratio and criteria for flow failure were developed. Evaluation of flow potential and behavior of ground from the N-value of SPT were also discussed.

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This note is related to a proposed vertical expansion of an existing municipal solid waste landfill situated in the north of Belgium. The interesting aspect of this landfill is the fact that the side slopes are composed of series of compacted inorganic waste bales. One of the main concern in this type of project is the possibility of slippage between the compacted bales. Large direct shear tests on waste were conducted in order to obtain the interface friction between the compacted bales of inorganic refuse. It was found that the stress strain relationship shows no peak data unlike tests with soil materials. More over the friction angle was found to be strain dependent.

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A comparative study of the static and dynamic response of a slope is carried out, using the large deformation theory of the updated Lagrangian formulation and the conventional infinitesimal theory. In the static analysis, a strength reduction method proposed by one of the authors is used to evaluate the safety factor of the slope. It is found that by the large deformation theory, the safety factor is larger than that calculated by the infinitesimal theory, and this difference becomes large along with the reduction of elastic modulus. In the dynamic analysis, it is observed that the large deformation theory gives smaller sliding displacement and larger response acceleration than the infinitesimal approach. It is concluded that in many cases the large deformation approach gives more adequate solutions.

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