Effect of Uncertainty of Soil Compressibility on Temporal Variations of Pore-Water Pressure at the Foundation of Structure

Today, as a result of the uncertainty and spatial variations of soil consolidation parameters and their effects on the pore-water pressure during the foundation settlement, it is common to apply the uncertainty-based probabilistic methods in such problems. In current study, the role of uncertainty of soil volumetric compressibility, as one of the effective factors on temporal variations of pore-water pressure during consolidation was investigated in Shaft region of Guilan province. In this respect, soil sampling was carried out in 9 bore holes (at the foundation of a steel structure and its yard located in Shaft town). Following the consolidation experiments, the log-normal distribution of soil volumetric compressibility was derived. Then, a computer code was developed in MATLAB to probabilistically analyze the partial differential equation of consolidation using Monte-Carlo simulation method. According to the results, increasing the number of random samples (of compressibility coefficient) from 100 to 1000 caused negligible effects. Whereas, the widening of probability density curves with time implies the dramatic effect of time on increasing the uncertainty of pore-water pressure. Meanwhile, for a given depth, the increased thickness of investigated soil layer caused greater uncertainty of pore-water pressure. Doubling the soil depth and investigated thickness of soil layer led to the increase of probability density by more than 20 times. Finally, during 100 days, the greatest temporal increase in coefficient of variation of pore-water pressure was obtained equal to 2.15 and 0.25 percent for 4- and 16-meters thick layers of soil, respectively.