Part 6 SPECIAL PROBLEMS: SHALE BEDS and SWIMMING POOLS
Shale lenses • One of the most vexing problems are discrete beds of expansive shale that often cross a developed pad • These seams will swell asymmetrically, as a function of effective normal force, as sketched here
Differential heave is a major problem for highways wherever they cross inclined strata containing clay (upper left) • Similar phenomena can occur due to frost heave, shown at lower left
Seepage from swimming pools constructed of porous gunite shells with water-cement ratios <0.45 can cause problems in expansive soils if structures are located close by, as sketched here.
Case study of distressed home in San Jose, CA. Instrumentation showed that most of the swimming pool seepage percolated through the floor of the pool shell, but sufficient moisture seeping from one side caused soils to heave, as shown.
The recommended solution included ample subdrainage around the gunite pool shell, and an HDPE membrane, sketched here.