Physical Model Study on the Static Behavior of PET Geostrip-Reinforced Back-to-Back MSE Walls

Physical model tests were conducted to investigate the mechanical behavior of PET geostrip-reinforced back-to-back MSE walls under static loading and the influence of vertical reinforcement spacing. Two reinforcement spacings were considered, and bilateral staged surcharges of 20–120 kPa were applied at the wall top. Settlement, facing displacement, reinforcement tensile load, lateral earth pressure, and vertical stress were monitored. The results show that all responses increased with surcharge, while their overall spatial distribution patterns remained generally stable. Wall-top settlement exhibited a double-peak distribution, and under 120 kPa, the maximum settlement of Model B was about 46% greater than that of Model A. Facing displacement showed an S-shaped profile, with an inflection point near 0.6H. Increasing the reinforcement spacing from 0.15 to 0.30 m resulted in higher tensile loads in individual reinforcement layers in the upper-middle region under the investigated conditions. Lateral earth pressure varied nonlinearly with height and peaked at about 0.77H. Vertical stress attenuated beneath the loading zones and was redistributed within the backfill. Overall, larger reinforcement spacing increased settlement, facing displacement, and reinforcement load, but had limited influence on the basic spatial response patterns.