Part 6Part 6

SPECIAL PROBLEMS:SPECIAL PROBLEMS:

SHALE BEDSSHALE BEDS

andand

SWIMMING POOLSSWIMMING POOLS

Shale lensesShale lenses One of the most One of the most

vexing problems vexing problems are discrete beds are discrete beds of of expansive shaleexpansive shale that often cross a that often cross a developed paddeveloped pad

These seams will These seams will swell swell asymmetricallyasymmetrically, as , as a function of a function of effective normal effective normal force, as sketched force, as sketched herehere

Differential heaveDifferential heave is a major is a major problem for problem for highways highways wherever they wherever they cross inclined cross inclined strata containing strata containing clay (upper left)clay (upper left)

Similar Similar phenomena can phenomena can occur due to occur due to frost frost heaveheave, shown at , shown at lower left lower left

Seepage from swimming poolsSeepage from swimming pools constructed of porous constructed of porous gunite shells with water-cement ratios <0.45 can gunite shells with water-cement ratios <0.45 can cause problems in cause problems in expansive soilsexpansive soils if structures are if structures are located close by, as sketched here.located close by, as sketched here.

Case study of distressed home in San Jose, CA. Case study of distressed home in San Jose, CA. Instrumentation showed that most of the Instrumentation showed that most of the swimming swimming pool seepagepool seepage percolated through the floor of the pool percolated through the floor of the pool shell, but sufficient moisture seeping from one side shell, but sufficient moisture seeping from one side caused soils to heave, as shown. caused soils to heave, as shown.

The recommended solution included The recommended solution included ample ample subdrainagesubdrainage around the around the gunite pool shellgunite pool shell, and , and an an HDPE membraneHDPE membrane, sketched here. , sketched here.