The interaction characteristics between reinforcements and soil are the key index in reinforced earth

which determines the stability of reinforced earth. Pullout test results show that the quantity of apparent frictional resistance between two-way geogrids and clay increases with the normal stress increasing. The failure format between two-way geogrids and clay is the entirety two-way geogrids pulled out when the normal stress is lower

but as long as the normal stress is higher than some certain quantity

the failure format between two-way geogrids and clay is changed from entirety pulled out to longitudinal gill pulled out. The apparent cohesion of entirety pulled out failure format is less than that of longitudinal gill pulled out failure format; and the apparent friction angle is reverse.