APPLICATION OF MONITORING SEEPAGE TO SPECIAL CASES OF MEMBRANE EMBANKMENT DAMS
The water retaining integrity of a membrane dam is dependent on the condition of the membrane. Because it is often difficult to thoroughly inspect the membrane during operation (it is submerged or buried), another indication of the trends in the membrane condition can be obtained by monitoring seepage at the toe of the slope. When seepage is increasing with time, it is an indication that membrane maintenance should be factored into upcoming annual maintenance budgets.
11.3.4 STRESS
MONITORING STRESS IN EMBANKMENT DAMS
In general it is much simpler to monitor strain in an embankment dam than stress, so stress monitoring is not frequently done. However, there are occasions when stress monitoring is desirable. Stress monitoring can be done using total pressure cells (see Chapter 3) which are typically installed during construction, or alternatively, using a self-boring pressure meter after construction. Total pressure cells can be installed in embankment fill to verify overburden and lateral stresses. Total pressure cells can not be installed after construction without disturbing the stress field of interest. The self-boring pressure meter provides an alternative that can be used post-construction, although it is a somewhat exotic piece of equipment.