Abstract
This paper describes the peat ground surface settlement due to the lowering of the water table by the well-point system.
This investigation was carried out for estimating the amount of settlement by the mv method.
Two model experimental tests and some soil element tests were performed to attain the objective.
One was a tank (φ=80cm, H=150 cm) model peat ground test.
At first, there was a water level at the surface ground level (H=130. 7 cm), and 13 differential settlement gages were laid in the peat ground used as the model. For the later, the water level was down from 130.7 to 70.7 cm.
As time passed the peat layer consolidated and the ground surface sank continuously.
Thirteen peat laid settlements were measured with the gages.
The other was a natural peat field test. The test was carried out on Syounai plain in the Yamagata district.
Actually, by well point system, the groundwater level sunk about 4. 5 m and, at some points, surface settlement measurements and cone penetration tests were carried out.
Some consolidation tests were carried out for some disturbed and undisturbed samples, and some coefficient of volume compressibilities (mυ) for the model test and the field test analyzed from the test data were acquired.
The results for this analysis are as follows.
Using the coefficient of volume compressibilities (mυ) which was measured by the consolidation test acting on seepage force and Δp is an additional effective stress lowering due to the water table by well-point system, peat groundsurface settlement agreed with the mυ method (S=Σmυ·Δp·H).
