Study on Characteristics and Spatial Heterogeneity of Deep Silt Soft Soil in Nansha Port Area

As the key index of geotechnical engineering investigation, soft soil parameters are the premise and basis for studying soft soil characteristics and solving soft soil engineering problems. Taking the deep soft soil in Nansha port area of Guangzhou as the research object, 371 groups of indoor geotechnical tests and 147 groups of field in-situ test data were collected, and the spatial characteristics of soft soil parameters are studied by mathematical statistics and random field theory. The results show that: Soft soil shows "four high and one low", to be specific, high water content, high liquid limit, large void ratio, high compressibility and low shear strength, it has strong regional and spatial heterogeneity, and the space-time effect is significant; The empirical formula between soft soil parameters are established, it is showed that the physical indexes of soft soil have better stability, smaller coefficient of variation and stronger correlation than the mechanical indexes; The water content, void ratio, compression coefficient, liquid limit and liquid-plastic limit index decrease with the increase of soft soil depth, while natural density, compression modulus, strength index and static cone penetration index increase slowly, the shear strength of vane first decreases and then increases; The autocorrelation distance has no obvious correlation with the increase of exploratory hole depth, the cone tip resistance index can better reflect the spatial variation characteristics of soil layer and the reproducibility of test results, and realize the transformation of soft soil parameters from "point" characteristics to "spatial" characteristics; The recommended value of soft soil judgment standard in this area is put forward, which provides a reference for the survey and design, soft foundation treatment and construction of silt soft soil in similar areas.