Roadway design and rehabilitation in Knoxville demands a thorough understanding of the region's complex residual soils and karst geology. Our geotechnical services cover the full lifecycle of pavement infrastructure, from pre-construction subsurface investigation to construction-phase quality assurance. The Tennessee Valley is underlain by the Cambrian-Ordovician Knox Group, where solutioning of carbonate bedrock creates pinnacled rockheads, erratic boulders, and the potential for sinkholes. Adhering to the latest TDOT Standard Specifications for Road and Bridge Construction, we characterize these variable ground conditions to mitigate differential settlement and pavement failure, ensuring designs meet the structural requirements of local agencies including the City of Knoxville Engineering Department.
Our field methodology relies on standardized In-Situ to derive design parameters compliant with AASHTO and ASTM standards. We deploy CPT (Cone Penetration Testing) to continuously profile subsurface stratigraphy and estimate soil behavior type, which is particularly effective in the alluvial deposits along the Tennessee River and First Creek corridors. This is supplemented by In-Situ programs, including Standard Penetration Tests (SPT) per ASTM D1586, to assess relative density in granular subgrades. For compacted structural fill and aggregate base courses, we perform nuclear gauge and field density testing using the sand cone method (ASTM D1556) to verify compliance with TDOT density specifications, typically 95% of standard Proctor maximum dry density for subgrade stabilization.
Knoxville's roadway projects span from interstate widenings along I-40/I-75 to residential street improvements on steep slopes in neighborhoods like Sequoyah Hills and Holston Hills. We frequently address slope stability concerns in cut sections through the residual soils of the Whiteoak Mountain fault zone. Our foundations analysis extends to bridge approaches, MSE retaining wall support, and the design of rigid and flexible pavement sections using the 1993 AASHTO Design Guide, calibrated for Tennessee's climatic region. For subgrade evaluation, we conduct laboratory resilient modulus testing and California Bearing Ratio (CBR) assessments on representative samples to predict pavement performance under local traffic loading and freeze-thaw cycles.
Our process begins with a targeted subsurface exploration plan to define the pavement profile. Disturbed and undisturbed samples are transported to our laboratory for classification and strength testing. Fundamental index tests, including grain size analysis by sieve and hydrometer (ASTM D422) and Atterberg limits determination (ASTM D4318), quantify the plastic fines content and expansive potential of the clay-rich Chickamauga formation soils. We deliver a comprehensive geotechnical report with pavement design recommendations, layer coefficients, and drainage considerations, providing Knoxville engineers and contractors with actionable data to construct durable, low-maintenance roadways that withstand the demands of East Tennessee's terrain.