A large urban infill development in the City of Los Angeles near the Pacific Ocean provided unique opportunity for gaining insight into the behavior of soft clays with high organic content under large scale surcharge program for extended period of time. Long term surcharge settlement monitoring data and pre- and post- surcharge investigations offered an extensive amount of data for analyzing and understanding the contributing factors of shear strength gains including the thickness and depth of soft clays, surcharge height and duration, drainage path for pore water pressure dissipation, and soil plasticity index. Continuous soil coring and Cone Penetration Tests (CPT) have been conducted to investigate the organic soils. Possible preliminary correlations could be formed to relate soil shear strength increase with surcharge height, insitu overburden pressure, and soil plasticity. Long term surcharge settlement monitoring also provided a unique opportunity to assess the magnitude and actual rate of secondary consolidation. The observed time rate consolidation was compared with theoretical one dimensional time rate consolidation calculations. Reasons for any discrepancy observed between actual time rate consolidation and theoretical calculation were explored to identify major causative factors that need careful evaluation for predicting time rates for similar projects. Based on actual surcharge settlement data, additional surcharge height and time frame were established for mitigating additional secondary settlements within the life expectancy of the proposed development.
展开▼
