Four centrifuge tests supplemented by calibrated numerical simulations were performed to evaluate passive wedge formation and limiting lateral pressures imposed on a large, stiff foundation during liquefaction-induced lateral spreading. In the centrifuge tests lateral pressures on the upslope and downslope faces of the foundation were measured using tactile pressure sensors. Lateral pressure distributions also were extracted from the simulations. Available methods to estimate the limiting lateral pressure distributions, including the Rankine, Broms, Japanese Road Association, and strain wedge methods were compared to the measured and simulated pressures. However, existing models did not capture the observed pressure distributions even when the size and shape of upslope passive wedge was defined directly from surface and subsurface displacement patterns in the centrifuge tests. A new semiempirical method is proposed to estimate limiting lateral pressures that accounts for the three-dimensional shape of the upslope passive wedge. This method produces an upslope limiting pressure distribution consistent with centrifuge-measured pressure distributions.

The analysis of sands, and the foundation systems with which they interact, are largely dependent on macroscale behavioral parameters that represent the aggregated response of several microscale characteristics. This research paper examines the influence of surface texture, or smoothness, on the behavior of sands. The challenge of estimating or measuring smoothness, due to its microscale feature domain, is addressed through an examination of six artificially graded sand specimens. These specimens are evaluated both visually and numerically to characterize their surface smoothness. The first approach described is a simple visual method that uses a smoothness scale consistent with those of roundness and sphericity. This method, which can be performed with a tool as simple as a hand lens, evaluates a group of representative particles collectively. The second approach is also a visual evaluation, but it utilizes images obtained via scanning electronic microscopy, traditional optical microscopy, and newer low-cost digital microscopes that can be rapidly connected to a smartphone or laptop. To validate these visual estimates, a novel third approach is introduced. This approach is a more objective numerical analysis measurement technique that enables rapid and economic quantification of smoothness. This technique may assist both practitioners and academics in their understanding of the macroscale response of coarse-grained soils. In addition to the visual methods, this research also conducted several laboratory index tests to observe the mechanical behavior of the specimens, considering their particle shape and surface smoothness properties. The results indicate that angular sands have greater minimum and maximum void ratios, a larger difference between the minimum and maximum void ratios, greater critical state friction angles, and greater flow rates through an orifice of fixed size. When adjusted for surface smoothness using the proposed approach, the behavior of the sands—particularly the limit void ratio results—appears to be more predictable in some cases. These results provide additional evidence of particle smoothness contributing to the strength behavior of sand, which may be particularly useful in the domains of slope stability, land reclamation, soil–structure interaction, and soil dynamics.

The purpose of this review paper is to summarize the literature on the behavior and performance of permeable asphalt (PA), examine the feasibility of applying PA to arterial streets in cold climates, and present recommendations to improve the success of PA in wider applications. The review presented here required examining existing data sources and scientific journal papers, along with interviewing professionals who have conducted studies or dealt with PA in a variety of locations. The conclusions and recommendations drawn from this evaluation are intended to be guidelines for agencies looking to potentially apply PA to arterial streets in cold climate regions. Literature selected for review included PA sites that had several of the following characteristics: high volume traffic, cold climate region, abundant annual snowfall and extreme average temperatures, used sand, salt, plows, and deicers in winter maintenance activities, and experienced studded snow tires. In addition, sites reviewed also had subgrade soils with adequate infiltration rates, deep groundwater, relatively little annual precipitation, and area frost depths of 24 in. below finished grade. It was not possible to have each case study reviewed address all criteria, but all of these factors were considered important to the review to provide accurate literature comparison, and they allowed us to ascertain and present general behavior and patterns regarding PA. In addition, a summary of recommendations on the application of PA to arterial streets in cold climates with respect to water quality treatment performance, hydrologic performance, materials and durability, and maintenance practices are also presented.

Particle smoothness refers to the surface texture of a sand particle on a small scale. This parameter may be used in conjunction with roundness (angularity) and sphericity in describing particle shape for engineering purposes. Smoothness is challenging to measure and quantify. This note describes preliminary evaluation approaches used to compare two identically graded sand specimens; one with an unaltered, smooth surface texture, and the other chemically etched to create a rougher surface texture. Visual observation indicated that the unaltered specimens were essentially the same as the etched specimens in terms of macroscale particle shape features (i.e., roundness and sphericity). On the other hand, the particles were significantly different in terms of the surface texture and roughness, as shown by visual techniques using scanning electron microscope and optical microscopy images. A tentative, easy-to-implement, visual particle smoothness scale is offered, designed to complement the roundness and sphericity estimates and measures commonly used to describe particle shape. Next, several simple laboratory index tests are completed on the unaltered and the etched specimens to observe differences in mechanical behavior. Limit density, flow rate, and angle of repose tests are undertaken. The results of the testing indicate measurable differences in the mechanical behavior of the unaltered versus the etched specimens. This further supports the importance of particle surface texture on the mechanical behavior of poorly graded sands. Additional research is underway to more completely quantify the contribution of particle smoothness of sands with respect to the other macroscale particle shape features.

Deflection walls were considered for mitigating lateral spreading-induced bending moments on large-dimension foundations. The efficacy of the walls was tested using dynamic centrifuge testing of a large-dimension rectangular foundation (caisson) with and without an upslope ground deflection wall. The ground deflection walls were modeled as buttressed sheet pile walls and were intended to deflect the laterally spreading ground around the caisson and reduce the pressure transmitted to the caisson. Three wall shapes (chevron, arch, and truncated chevron) were tested in all-sand profiles and profiles with a clay cap underlain by sand. In contrast to the unprotected caisson tests, the deflection walls successfully redirected the laterally spreading sand-only profiles around the caisson and minimized passive wedge development upslope of the caisson. Maximum lateral pressures measured on the upslope face of protected caissons ranged from at-rest pressures to the total vertical stress and were about 30%–50% lower than those measured against unprotected caissons. Based on these results, the proposed buttressed sheet pile walls may be suitable to mitigate lateral spreading forces on existing foundations. These results also suggest that newly constructed large foundations or pile groups may be arranged in a diamond or circular pattern to better mitigate potential lateral spreading earth pressures.