Investigation of the Factors Affecting Anchored Geotextile/Geonet System by Model Tests
Date Issued
2011
Date
2011
Author(s)
Chang, Yu-Lung
Abstract
The anchored geotextile/geonet system (AGS) is a technique for slope protection. In the system, geotextile/geonet is placed on the slope to control soil loss and to provide drainage; while anchors are driven through the fabrics into the soil to stabilize potential failure planes. By combining these two elements, geotextiles and anchors, the AGS can develop a strong armoring network for protecting slopes. This technique has been put into practice through years with good results.
The main focus of this research was to investigate the effects of anchoring force distribution, fabric properties, and soil permeability on the AGS. Model slopes were established by using different anchoring forces, various geotextiles, and soils as testing variables. The slopes were triggered to fail by seepage. The image of the movement of soil particles was recorded by a particle image velocimetry (PIV) during the test. Water pressures at several locations in the slopes were monitored as well. These data provided references for slope stability analysis using limit equilibrium concept.
The test results showed that the force in the anchor that was located near the bottom of a slope was high due to the effect of soil’s weight. Although a dense fabric has good tensile strength, its drainage function is also poor. As a result, seepage induced more obvious instability in the slope that used the dense fabric. Moreover, a natural geotextile tested was apt to induce necking phenomenon, which caused the soil to clog inside the geotextile. Consequently, the water pressure was built up and slope instability occurred. The slope consisted of more permeable soil was easier to be affected by a seepage flow. In this case, the beneficial from the AGS was less significant. In all the model tests, the slopes failed slowly rather than abruptly and no soil was observed being carried away through the geotextiles. This evidence demonstrated the capability of the AGS in maintaining slope stability, even though some anchors were already failed.
Subjects
slope
model test
geotextiles
anchor
permeability
Type
thesis
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