Improvement of sandy soil with cylindrical cavity by using geogrids

Abstract EN

This study is focuses with the possibility of using Tanser SS2 geogrid as a reinforcement material to increase the bearing capacity and reduce settlement under strip foundation located on sandy soil with cylindrical cavity.

Forty five laboratory model tests were conducted using a steel box with 1250 mm in length, 800 mm in depth and 250 mm in width.

Increment loads were applied on strip footing with 100 mm in width and 250 mm in length.

Since the length of the model foundation was approximately the same as the width of the test box and length of the cavity, it can be assumed that an approximate plane strain condition exist during the tests.

For each model, the relationship between the applied pressure and the corresponding settlement was detected.

From the results of a series of laboratory tests, it was found that the bearing capacity ratio (BCR) of the soil increases with increasing in width of geogrid, (b/d) specially when the cavity center coincides with the centerline of the strip footing (X / d = 0).

The effect of geogrid width will reduce with moving the cavity away from the strip footing.

When the width of the geogrid layer was high (b / d), the maximum increase in bearing capacity ratio can be noticed at high depth of geogrid layer (h / d = 3), and this bearing capacity ratio becomes very low at small geogrid width for same value of (h/d=3).

At zero lateral distance ratio (X/d) and two layer reinforced, the higher generated bearing capacity are noted when the vertical distance between two layer geogrid is (S / d = 1, i.e optimum value), but at (S / d = 0.5), the values of footing resistance are lowest.

The effects of number of layer (N) on the bearing capacity of strip footing are very small at low value of geogrid width.

At geogrid width (b / d > 1), the case of geogrid (N = 3, i.e optimum value) record the highest values of the bearing capacity ratio.

The location of peak strain readings of the geogrid surface is depends upon the cavity position.

As the geogrid layers were near to the base of the footing, the values of reinforcement strains were increased.