The objective of this paper is to propose a compaction control method that facilitates the use of expansive soil, as embankment material for highways in humid climates. Three types of expansive soils, utilised as general embankment fill in Southern China, were selected for investigating the physical, compaction, and shear strength properties. The compaction-control method was proposed based on the compaction curve revealed by the dry preparation method, associated with the corresponding soaked California bearing ratio. The site test and long-term monitoring were conducted in an embankment in Ningming, which was filled with compacted expansive soil controlled by the suggested method. The laboratory test results showed that the maximum dry unit weight obtained from the dry preparation method was less than that generated from the moist preparation method, while the optimum moisture content acquired from the dry preparation method was greater and closer to its natural moisture content. The moisture content corresponding to maximum CBR was 2% larger than the optimum moisture content. The in-situ monitoring results presented that the moisture content of the constructed embankment was close to its natural moisture content or plastic limit, the maximum settlement was 70.6 mm, and the maximum horizontal displacement was 20 mm.

Percussion driven earth anchors (PDEAs) are driven into soils using an installation steel hammer rod. PDEAs are relatively easy to install and have gained wide applications recently. The Texas Department of Transportation (TxDOT) planned to use these anchors for slope stability mitigation along the Clear Fork Trinity River at Interstate Highway 20 (IH-20) in Benbrook, Texas. However, there are no straightforward design and construction guidelines for these systems. In addition, the pull-out capacity and failure mechanisms of PDEAs in clayey soils have not been thoroughly studied. In this study, three PDEAs, Duckbill model 138 II (DB-138 II), were installed and tested on the proposed west channel bank slope to acquire the ultimate pull-out capacity. The anchors were embedded to an average depth of 10 feet into the slope bank, predominantly consisting of sandy lean clay (CL) soil. The slope was graded at an average 2:1 to 2.5:1 configuration. After installation, the anchors were subjected to an upward pull-out force using a hydraulic jack system to measure their pull-out capacity. The pull-out load, displacement, and strains were continuously recorded with a load cell, a linear variable differential transformer (LVDT), and a strain gauge, respectively. Pull-out load versus displacement curves were produced and analyzed to determine the behavior of the anchors. An empirical estimation method was then chosen to estimate pull-out capacity based on undrained shear strengths obtained either from laboratory tests or in situ Texas cone penetration (TCP) data. The comparison between estimated and field-obtained pull-out capacities showed that the pull capacity estimated using TCP data resulted in reasonably good agreement with the field-obtained capacity. The field experiment results help us to understand the relationship between the calculated and actual field pull-out resistance when PDEAs are used in clayey soil slopes.

Geothermal energy is a renewable, sustainable, clean (i.e., zero carbon emission), and directly used an energy source that has been successfully used for bridge and pavement deicing. However, existing geothermal bridge/pavement deicing designs mostly rely on hydronic loops, which are embedded within concrete decks during bridge construction phase and are considered as internal heating. This paper presents a numerical feasibility study of an external geothermal heated bridge deck design in which the hydronic loops are attached to the bottom of the bridge deck and encapsulated in a layer of geofoam. A series of parametric analyses are performed to investigate the external heating process in comparisons to internal heating. These analyses contain various ambient temperatures, inlet temperatures, wind speeds, and flow velocities. The results demonstrate that external heating can heat the bridge deck to above freezing temperatures in mild winter weather compared to internal heating. Limitations of both heating systems are also evaluated since both systems would be unfeasible for extreme environmental conditions such as high wind speeds (more than 8.94 m/s) and lower ambient temperatures (lower than −2°C).

A comprehensive understanding of the heat transfer mechanism of hydronically-heated structures is crucial to predicting their heating performance. However, few studies considered the heat transfer at the interface of heating pipe and host material. In this paper, heat transfer at two critical interfaces for hydronically-heated concrete structures, e.g. pipe-concrete interface and concrete-air interface, has been tested and analyzed. Two concrete blocks, one with an embedded cross-linked polyethylene (PEX) pipe and one with an attached PEX pipe, were fabricated to represent heated bridge decks for the heat transfer study. The two blocks were tested inside a freezer box in a series of heating response tests at varied room and fluid temperatures. Measured temperatures at different depths were used to find the convection heat transfer coefficient and the thermal contact conductance between the concrete and PEX pipe through equations developed via finite difference method (FDM). Finite element models (FEM) of the two blocks were developed to verify the thermal contact values derived from a 1-D thermal resistance model. A comprehensive analysis of the temperature response of the models was performed, especially at the two interfaces, and the FEM models were able to predict the lab measurements accurately. The obtained contact heat transfer coefficient and the FEM models can be used for all hydronically-heated structures.