There are several existing methods for determining groundborne vibrations in buildings due to subway train traffic that are essentially based on empirically derived relationships. These methods are not able to handle buildings with unique foundations in unusual geological conditions with reasonable accuracy. The case in this study, which comprises a four-story podium block enclosing twin double-box tunnels within the confines of its ribbed-wall foundations, presents such a situation. In contrast, this paper presents a more accurate approach, which employs the finite-element method and is capable of modeling the complicated subway-soil-structure interaction problem. Furthermore, an analytical model is incorporated to provide the train-loading input. For verification, in situ measurements were taken, both at the tracks and within the building. The analytical results obtained showed reasonable conformity with the measurements taken.

A constitutive model, based on the concept of scaled memory (SM), is presented to describe the undrained behavior of anisotropic clays subjected to generalized loadings. The SM capabilities that were previously established for one-dimensional cyclic responses are extended to six-dimensional monotonic loadings. SM is simpler than multiyield surface plasticity, and just as capable in modeling anisotropic behavior. The performance of the SM model is illustrated by simulating the stress-strain responses of K₀ -consolidated clays during combined triaxial-torsional tests.

A constitutive model, based on the novel concept of scaled memory (SM), is presented to describe the hysteretic stress-strain response curves of soils during one-dimensional loadings. SM transforms the nonlinear plastic modulus into a piecewise-linear distribution, and then uses this simplified distribution for generating the plastic modulus during cyclic loadings. SM generalizes the models of Ramberg-Osgood and Hardin-Drnevich, and is simpler than, but as capable as, multiple yield surface plasticity. We extend SM to anisotropic behavior, and present a technique to calibrate the material constants from laboratory data. The SM theory, although applicable to six-dimensional stresses, is unfolded only in one dimension in this paper. Its usefulness is illustrated by simulating several cyclic stress-strain responses for clays and sands.

Liquefaction triggered by earthquakes is a source of major damage to structures resting on loose to medium sandy soils. The use of energy levels to define the onset of liquefaction has been validated in a previous study involving sinusoidal excitations. The present investigation extends the use of the energy concept to the kind of random excitations present in an earthquake time series. Tests conducted on sand specimens under several confining pressures and at different relative densities support this approach, which provides a solid and suitable link between laboratory and field behavior.

There are many geotechnical engineering support systems (for example, bore-injected minipiles, grouted anchors, grout in the void around a tunnel liner) where it is advantageous to inject a cement grout under pressure. A mathematical model is developed in this paper for the physical process that occurs as the grout consolidates (similar to a clay soil) under the applied pressure and expels its excess water into the surrounding soil under conditions of impeded drainage. The model is then used to calculate such parameters as the average degree of consolidation of the grout as a function of time prior to set and the change in the borehole radius. A series of specially designed experiments for a variety of conditions provide data that compare favorably with the theoretical predictions and thus lend credibility to the usefulness of the mathematical model for characterizing the physical situation that occurs during such operations in the field.

In general, roughness profiles of rock joints consist of nonstationary and stationary components. At the simplest level, only one parameter is necessary to quantify nonstationary joint roughness. To capture the nonstationary roughness, it is suggested that the average inclination angle I , along with the direction considered for the joint surface, be used. Most natural rock-joint surface profiles do not belong to the self-similar fractal category. However, they may be modeled by self-affine fractals. It is shown that even though the fractal dimension D is a useful parameter, it alone is insufficient to quantify the stationary roughness of non-self-similar profiles. A new strength criterion, which includes three roughness parameters ( D , I , and a spectral coefficient, K _s ), is suggested for modeling the anisotropic peak shear strength of rock joints at low normal effective stresses. Joint roughness data should be used to estimate the roughness parameters in different directions on the joint surface. Parameter D reflects the rate of change in length of the profile in response to a change in the scale of measurement r . Parameter K _s may be used to model the scale effect. A validation study shows that the new equation has good capability to predict the anisotropic peak shear strength of joints. In practice, to allow for modeling uncertainties, the new equation should be used with a factor of safety of about 1.5. Comparisons are also shown between the predicted shear strengths based on Barton's equation and the measured peak shear strengths.

Previously published methods for solving the force distribution and geometric profile of an embedded anchor chain involve numerical solution by an incremental integration technique. By rationalizing the problem, closed-form expressions for both the load development and chain profile have been derived. These expressions greatly simplify the procedure for estimating the load and inclination of an embedded chain at some connection point in the soil. The analytical work is corroborated with extensive laboratory test results.

Although liquefaction is a major cause of earthquake damage, little harm occurs unless the liquefied condition leads to some form of ground disruption or ground failure. Thus, the ability to accurately predict potential for ground-surface disruption is a major concern for geotechnologists charged with the safe siting of constructed works. In 1985 Ishihara presented preliminary empirical criteria to assess the potential for ground-surface disruption at liquefaction sites. Those criteria are based on relationships between the thickness of liquefiable sediment beneath a site and the thickness of overlying nonliquefiable soil. The purpose of this study is to further evaluate and verify Ishihara's criteria by testing them against thicknesses calculated from a wide range of earthquake and site conditions. The newly developed data lead to the following conclusions: (1) For sites not susceptible to ground oscillation or lateral spread, the thickness bounds proposed by Ishihara appear valid; (2) for sites susceptible to ground oscillation or lateral spread, the bounds suggested by Ishihara are not valid for the prediction of ground-surface disruption.

This note presents an inexpensive method of reducing the cell-fluid leakage in a long-duration consolidation/permeability test in a triaxial cell. It involves two membranes sealed with hose clamps over two O-rings and silicon grease at top cap and base, and a vegetable oil as cell fluid. It reduces leakage to an imperceptible level for a membrane immersion age of 7 days, beyond which small leakage appears and correction for this can be applied to the drainage volume measured in a consolidation stage. Careful selection of specimen diameter and minimum gradient combined with the inflow and outflow measurement as per ASTM D5084 minimizes the effect of leakage on permeability measured in the suggested setup.

The stability of a soil slope is analyzed based on the experimental results of a centrifuge test. The failure mechanism recorded in the model test closely resembled that which occurred in the field. Excess pore pressure generated in a sand seam sandwiched between two silt layers contributed to the lateral sliding. The slope angle was significantly reduced after the simulated earthquake. The experimental results are in accordance with the lateral sliding observed at Valdez during the Alaska earthquake of 1964.