Answer Happy

Design a geosynthetic system around a subsurface drainage system that will adequately prevent soil from migrating into the drainage aggregate (retention criterion) while allowing water to exit from the surrounding soil (permeability criterion). The geosynthetic system must survive the installation process (survivability criterion) as well as the life of the structure (clogging resistance criterion). The trench drains that are placed adjacent to a tow-lane highway are to intercept groundwater. The geosynthetic material will be wrapped around the aggregate drain stone. Following specific site data: (1) High groundwater table, (2) drain is to prevent seepage and shallow slope failures, which are currently a maintenance problem, (3) depth of trench is 1.2m, (4) soil samples along the proposed drain alignment are nonplastic and (5) gradations of three representative soil samples along the proposed drain alignment are give in Table 1 Table 1: Gradations of the Three Representative Samples Along the Proposed Drain Alignment Sieve Size (mm) 25 13 4.76 1.68 0.84 0.42 0.15 0.074 Sample A 95 93 90 88 77 50 8 3 Percent Passing, By Weight Sample B 98 97 95 92 83 73 35 20 Sample C 96 95 93 90 80 72 13 2