**3.2. Short-term compressive behavior**

**Figures 13–15** show all the results of compressive strength-strain curves at different temperatures (23, 35 and 50°C) and elongation rate (0.1, 0.5, 1.0, 5.0 and 10mm/min).-

In here, the compressive strength decreases and the deformation value increases according to the temperature. And the initial slope of this curve decreases greatly with increasing temperature, and the elastic modulus with temperature increases in the given strain range.

**Figure 14.** Plot of compressive behavior curves according to various deformation rates at 35°C test temperature: (a) bi-planar- and (b) tri-planar.

**Figure 15.** Plot of compressive behavior curves according to various deformation rates at 50°C test temperature: (a) bi-planar- and (b) tri-planar.

Considering the landfill's severe temperature conditions, this decrease may be affect the longterm flow capacity of the geonet drainage.-

## **3.3. Short-term transmissivity**

The flow capacity data as logarithm of transmissivity as a function of normal pressure (log value) is presented in **Figure 16**. This type of plot more clearly reveals the material response to applied loading conditions. **Figure 16** shows a continuous decrease in transmissivity from

**Figure 16.** Plot of transmissivity results of various geonet samples: (a) gradient—0.1, (b) gradient—0.5 and (c) gradient—0.5.

8.2 to 0.25, 9.53 to 2.62 and 8.2 to 1.16 (×10−<sup>3</sup> ) at 0.1 hydraulic gradient for bi-planar, tri-planar and cylindrical type geonet, respectively. Also in other hydraulic conditions show same trend as 0.1 hydraulic gradient. It is clear from **Figure 16** that bi-planar and cylindrical type show dramatic decrease of transmissivity above 600 kPa.

However, the cylindrical type geonet has more strong flow capacity compare to the bi-planar geonet even though there is a roll-over effect. On the other hand, the tri-planar geonet shows the excellent resistance to the thickness decrease.

The transmissivity of the tri-planar geonet is very high but decrease gradually with increasing normal pressure (compressive strength). This is due to the tri-planar geonet structure and means the stability of tri-planar geonet even though very high normal pressure (2000 kPa) and hydraulic gradient (1.0).

Therefore, it can be concluded that the triplanar geonet drainage pattern is linear and that a tri-planar geonet with a zig-zag-shaped flow pattern can discharge the liquid very effectively even when the thickness is the same as the bi-planar geonet.

From these results, it is considered that the most important factors affecting short-term flow capacity of geonet are drainage path and drainage pattern (e.g., linear or zigzag type) and geonet thickness.
