A new numerical method is introduced to analyze traffic‐induced ground vibrations three‐dimensionally on the basis of a dynamic elastic finite element method. A set of examples are examined to investigate the effect of pavement structures on reduction of ground vibrations. This technique, using an extended thin‐layered element method, can account not only for irregularities in near fields, including pavement structures, but also for traveling waves to far fields. Furthermore, weights, velocities, intervals, and vibrating conditions of vehicles can be taken into account. Now, given that moving loads are composed of static and dynamic components, the analytical results indicate that the dynamic component is a much more significant factor in causing ground vibrations than the static components. It is understood from the results that pavement structures have a large influence on ground vibrations, and that stiffness and damping of the pavement materials are the important factors. This statement confirms that we can reduce ground vibrations by using appropriate pavement structures.

The upper‐ and lower‐bound theorems of classical plasticity are used to examine the undrained stability of a shallow square tunnel under conditions of plane‐strain loading. Rigorous bounds on the loads needed to support the tunnel against active or passive failure are derived using two numerical techniques that are based on a finite element type of discretization. Both techniques assume a perfectly plastic soil model with a linearized Tresca yield criterion and lead to large linear programming problems. The solution to the lower‐bound linear programming problem defines a statically admissible stress field, whereas the solution to the upper‐bound linear programming problem defines a kinematically admissible velocity field. For the range of tunnel geometries considered, the solutions obtained typically bracket the exact collapse load to within 15% or better. Where appropriate, the results for the upper‐bound formulation are verified using a variety of rigid block mechanisms.

The performance of reinforced earth structures depends on the mobilization of interfacial shearing resistance between soil and reinforcement. This criterion typically eliminates the use of fine‐grained soil as a backfill material in reinforced earth structures. Considering the distribution of induced interfacial shear stress in soil around the surface of the reinforcement, it has been shown that only a thin zone of frictional material around the reinforcement is required to mobilize almost full interfacial shearing resistance of sand. Six series of pullout tests have been conducted, with different types of reinforcement, to study the effect of thickness of sand (frictional material) around the reinforcement on the pullout resistance. Sawdust and kaolin clay have been used as bulk backfill material, providing the soil with negligible friction. With low‐friction‐strength soil as bulk material, a 15‐mm thickness of sand around the reinforcement is required to increase the interfacial shearing resistance to that with sand as the bulk material. With this new technique, low‐frictional fine‐grained soils can be used as bulk backfill material in reinforced earth constructions.

Track support failure and rehabilitation of 14 km of railway mainline built in 1980 over a compacted clay (liquid limit 50‐70) is presented. The failed construction substituted a 300‐mm thick 5% lime stabilized layer for subballast. Ballast, 300‐mm thick below the tie base, supported prestressed concrete ties of similar design to those used in the Northeast Corridor reconstruction. Rehabilitation addressed the problems associated with subgrade pumping, track stiffness/softness, internal and external drainage, equivalent granular cover (total depth), and the compatibility of the ballast's toughness and mineral hardness in relation to the aggregate in the concrete ties. Reconstruction used inexpensive, locally available sand‐sized material for the subballast. A custom made geotextile was incorporated for extra safety. The rehabilitated track, carried out in 1984, has performed excellently.

Large‐scale loading tests were conducted on closed‐toe and open‐toe piles driven into dense submerged sand confined in a pressure chamber. Unit load‐transfer relations were developed and related to stress conditions in the chamber. Ultimate shaft resistance in compressional loading was found to be approximately equal to the ambient lateral effective stress in the chamber before driving, and was generally not dependent on the geometry of the toe. From this observation it can be inferred that because of installation and loading effects the operative earth‐pressure coefficient on the pile shaft approximately doubled from the ambient value that existed before driving. In uplift, ultimate shaft resistance was about 20% lower than in compression, regardless of depth. The open‐toe piles consistently remained plugged during static testing but nonetheless exhibited lower bearing capacity than the closed‐toe piles. This can be explained by deformation and compression of the soil within the plug as a means of effectively reducing the rigidity index of the soil against which the toe bears.

A laboratory study is conducted to evaluate the' long‐term resistance to percolation of grouted sands, using chemicals that represent the more common industrial waste effluents. Such performance data is necessary if grouts are to be considered for sealing off hazardous waste sites. Six different grouts are tested: acrylate, urethane, Pene‐grout, sodium silicate, glyoxal‐modified sodium silicate, and sodium aluminate‐modified sodium silicate. Water, eight chemicals, and two real‐site wastes are used as permeants. The acrylate grout exhibits very low permeability with water, has excellent resistance to the paint and refinery wastes and sodium hydroxide, and performs satisfactorily with cupric sulfate, ethylene glycol, and xylene. The urethane grout has low permeability with water, remains relatively impervious with acetone, aniline, ethylene glycol, methanol, paint and refinery wastes, and performs marginally well with cupric sulfate and hydrochloric acid. The Pene‐grout has moderately low permeability with water, good resistance to ethylene glycol, and, at low‐flow quantities, to acetone and 1N solution of hydrochloric acid. The silicate grouts are quite pervious even with water, but generally change little with the chemicals.

A probabilistic model for evaluation of differential settlements of a tripod platform founded on a clay deposit is formulated based on conventional methods for prediction of consolidation settlements. The model accounts for uncertainties in the loading and deformation properties of the clay and is based on a random field representation of the spatial fluctuation structure of these deformation properties. The practical application of the model is illustrated by presentation of calculations for an example platform. Probability calculations are performed by a first‐order reliability method as well as by directional simulation. Results from the use of these two different methods are compared, and a sensitivity study is included.

The increase in slope stability by application of discrete surface loads depends in part on the orientation of the load. For stabilization systems such as anchored geosynthetics, the load orientation corresponds to the angle of anchor installation. A theoretical study is performed to determine the optimum orientation of such anchors in purely cohesionless soils to maximize the increase in slope stability. Three cases are analyzed: a hypothetical surface load without anchorage, surface load with grouted end anchorage, and surface load with driven friction anchors. The last case involves the most interesting analytical solution since the optimum anchor orientation is a function of the slope geometry, the in situ stresses, and the desired increase in factor of safety. The required length and spacing of anchors depend, in addition to the aforementioned factors, on the anchor diameter, the internal friction angle of the soil, the soil‐anchor interface friction, the strength of the geosynthetic, and the depth of the potential failure surface. A simplified equation is given for the anchor orientation, and a design chart is presented for determining spacing and length requirements. An example problem illustrates the importance of proper anchor orientation.