The purpose of this test was to determine the durability of the manhole cover adapter and how it would perform over a life span of 50 years. With a hydraulic lift, we put the manhole cover adapter through repetitive cycles of up and down movements with a 4″ travel distance. Each lift represented one year of frost heaving. This test was developed to check for points of wearing and potential damage locations (i.e fatigue), and to observe the functionality of the device in a simulated environment.
The test proved that the manhole cover adapter was capable of withstanding these cycles of up and down movement without causing structural damages. Loading the unit from the jack and the skid steer did not cause any damages of alter the function of the unit. Slight surface wear was observed at the sliding pins. This was to be expected and was not substantial enough to cause a concern. By greasing the joint, this allowed for smooth operation and permitted the unit to extend and retract without binding.
During the test, asphalt cracking around the perimeter of the wings showed strong evidence of a failure caused by the testing method. The reason for this cracking was determined to be from the jacking of the unit. This was forcing the extension rather than natural frost heaving. During natural frost heaving, the soil expands in a uniform manner and will not create voids. Voids were formed when the unit was jacked up as it lifted and separated the asphalt from the soil. This loaded the connection with excessive stress causing the asphalt to crack.
We were able to gather enough data from this test however to confidently present it to the City of Summerside and come into an agreement that allowed us to further test it by installing it into a street.
