Laboratory and numerical investigation of machine foundations reinforced with geogrids and geocells

Abstract

The manuscript describes the results of large scale field tests and numerical studies conducted on geosynthetics reinforced soil beds supporting model machine foundation. A series of vertical mode block resonance tests are conducted over a rigid concrete footing resting on different reinforced soil conditions. The tests are performed in a test pit of size 2 m × 2 m × 0.5 m using a concrete footing of size 0.6 m × 0.6 m × 0.5 m. Four different conditions, namely, unreinforced, single layer geogrid reinforced, two layer geogrid reinforced and geocell reinforced conditions were considered. The tests are performed under six different dynamic force levels using a Lazen type mechanical oscillator. In total, 38 number of field tests are conducted. The dynamic response is studied in terms of reduction in resonant amplitude, peak particle velocity (PPV) and improvement in dynamic properties of the soil. Experimental results revealed that the displacement amplitude of vibration significantly reduced in the presence of geosynthetics. The maximum reduction is observed in the presence of geocell reinforcement as compared to the other conditions. In the presence of geocell reinforcement, resonant amplitude is decreased by 61% and the natural frequency of the soil system is increased by 1.38 times as compared to the unreinforced condition. In addition, the geocell reinforcement found to reduce the PPV by 48% at a distance of 0.5 m from the footing face. The elastic uniform compression of the foundation bed is improved by 91% in the presence of geocell reinforcement. Further, the experimental results are validated with the numerical studies conducted by using finite difference package FLAC3D. The encouraging agreement in the dynamic behavior of reinforced soil is observed between the numerical and experimental studies. The numerical results revealed that the lateral spreading of vibrations is significantly controlled in the presence of geocell reinforcement.