Infiltration control using capillary barriers for conservation of historical tumulus mounds

Abstract

Tumuli were constructed more than 1300 years ago and have been conserved as historical cultural heritages but many of them are seriously damaged by rainfall infiltration. In the present paper, a capillary barrier formed at the coarser-finer soil interface under unsaturated condition is studied as a feasible means for protecting tumuli from rainfall induced damages. The mechanism of water shielding by a capillary barrier and the diversion capacity are quantitatively discussed by conducting model chamber tests and numerical analyses. A series of the model chamber tests indicates that a capillary barrier is formed when the coarser grained soil has lower hydraulic conductivity than that of the finer grained layer and the diversion capacity is controlled by the inclination of the soil interface, the thickness of the finer grained layer and the intensity of precipitation because these factors are related to the degree of the difference in hydraulic conductivity of the finer and coarser grained soils.