China
Africa
Explore chapters and articles related to this topic
Simplified finite element consolidation analysis of soils with vertical drain
Published in Jian-Hua Yin, Guofu Zhu, Consolidation Analyses of Soils, 2020
The lower marine clay is of medium plasticity, with plasticity indices ranging from 25 to 40%. A bulk unit density value of 1.85 Mg/m3 is recommended for design. In the recompression stress range, compressibility is low, with recompression strain indices ranging from 0.02 to 0.05. In the normally consolidated range, the soil is quite compressible, with compression strain indices, Ccs, ranging from 0.20 to 0.35. Respective design values of 0.035 for Crs and 0.25 for Ccs are recommended for design. Coefficients of secondary compression Cαε in the virgin zone range typically from 1.7 to 3.0%, and 1.7% is used in the analysis. Coefficients of vertical hydraulic conductivity estimated from consolidation tests are typically 2×10−10 to 3×10−10 m/sec, with a mean value of 2.5×10−10 m/sec. The in-situ horizontal coefficients of hydraulic conductivity from variable head permeability tests are 4×10−10 to 8×10−10 m/sec, and a value of 6.2×10−10 m/sec appears to be a suitable average.
Experimental study on reinforcement of marine clay by artificial hard shell layer composite foundation
Published in Marine Georesources & Geotechnology, 2022
Chao Wang, Fangjin Zeng, Shihu Gao, Guohui Yuan
With the rapid growth of population and economy and the shortage of land resources, marine clay is often used in coastal areas for land reclamation. After that, the marine clay reclamation area is strengthened and improved to increase land resources for people’s production and living. However, the marine clay in the reclamation area has the distinctive characteristics of high moisture content, great compressibility and almost zero shear strength (Wang et al. 2017, 2018, 2019a, 2019b). It is quite difficult to build roads on these soils. Several meters of hard shell layer can be formed on natural marine clay foundation through weathering, evaporation and a series of natural processes. The natural hard shell layer has good bearing capacity and can sometimes be used directly as foundations (Hao and Chen 1993). However, due to various factors such as location, bearing capacity and construction conditions, it is difficult to apply natural hard shell layer in practical engineering. The soil under cement or lime can be rapidly stabilized and can greatly change the physical and mechanical properties of soil, and be used as building materials (Chen et al. 2019; Okyay and Dias 2010; Pham, Koseki, and Dias 2021). The method of in situ curing to form hard shell layer has been widely used in European countries (Jelisic and Leppänen 2003), but in road engineering construction with strict settlement control, it is far from enough to only meet the requirements of bearing capacity.
Effects of frequency and CSR on dynamic properties of marine clay in drained condition
Published in Marine Georesources & Geotechnology, 2022
Hao Liu, Si Yan, Jie Yin, Jiang-Qiao Fan, Yong-Hong Miao, Fan-Bo Zhou
Marine clays associated with fine-grained soils have specific properties, such as large void ratios greater than one, high water content greater than liquid limit (LL), high compressibility, low permeability, and low shear strength (less than 25 kPa), which are widely distributed around the world, especially in coastal areas (Feng et al. 2014; Xu and Yin 2016; Wang, Desai, and Zhang 2019; Zhao and Zhao 2021). The major challenge for any infrastructure or building structures constructed on marine clay foundations will be the potential danger from excessive settlement and large horizontal displacement of marine clays. Additionally, a large volume of dredged sediments with high water content is generated annually from the bottom of rivers, lakes, harbors, and other waterways during dredging projects. A possible way is to use these very soft dredged materials as fills for land reclamations or port construction after applying some improvement or remediation methods.
A numerical study for predicting the capacity of skirted foundations in clay subjected to cyclic loading
Published in Ships and Offshore Structures, 2022
Jichao Lei, Fen Li, Liang Sun, Lixian Wang, Yu Hu
Marine clay is widely distributed in the coastal and offshore areas and has the characteristics of high-water content, high void ratio, and low strength. Such clay layers subjected to cyclic loading have a great impact on the bearing capacity of the circular skirted foundation. Previous researchers usually choose the Tresca model as the constitutive model of clay and assume the undrained shear strength as either linearly increasing with depth or uniform (Vulpe et al. 2015; Gourvenec et al. 2014; Raj et al. 2019, Vulpe et al. 2015). As mentioned above, most previous researchers only considered the static bearing capacity of the circular skirted foundations. A few researchers applied the dynamic constitutive model to study its cyclic bearing capacity (Emdadifard and Hosseini 2010; Kourkoulis et al. 2014; Cheng et al. 2016a). Although such models can consider the dynamic characteristics of clay in individual cycles well, it always focuses on the uniaxial cyclic bearing capacity without considering the effect of combination of HVM loads. Moreover, the stress–strain relationship during cyclic loading, which may consume considerable computing resources, is not the focus of the bearing capacity calculation of the skirted foundation. Besides, there are also scholars using empirical model established by experimental data fitting to study the cyclic bearing capacity of foundation (Ke et al. 2010; Skau et al. 2017). Although these methods are simple and easy to use, the establishment of empirical models requires a large number of experiments, and the above studies don’t establish a systematic method to calculate the bearing capacity of skirted foundations embedded into distinct soils, which is not conducive to the engineering application.