Experimental evaluation of the size and distribution of lateral pressure on the walls of the excavation support

Abstract

The paper presents the results of a research experiment that aimed at verifying the size and distribution of earth pressure acting on the excavation support with reference to commonly used theoretical solutions. The tests were carried out on the object in its full scale. For this purpose, a 6 m deep excavation was made in the testing ground. It was secured with a support system i.e., a point chamber consisting of corner columns and a system of three rows of fin plates. The tests relied on various measurement techniques. The earth pressure was measured with sensors specially designed and manufactured for this research experiment. Simultaneously with earth pressure measurements, there were measured stresses in the support plates with the use of strain gauges and deflections using laser scanning and a calibrated measurement patch. The tests were conducted for three months, with different backfill load. The measured values of earth pressure increased in a manner similar to the values of hydrostatic thrust, reaching max. 30 kPa before making the excavation and 25 kPa after making the excavation and assembling the support. The results were consistent with the values determined in line with commonly used theoretical solutions. The stresses caused a 15 mm deflection in the plates. Backfill load significantly affected the value of thrust down to a depth of approx. 4 m but did not cause a further increase in the deflection in the plates.