With the development of the marine traffic engineering in China, it is needed to develop the construction method of artificial island in open sea. An artificial inland of 97962 m2 was built in a cross sea bridge project in southeast sea of China. The seawater depth at low tide at the location is 10 m depth and the seawater level at low tide is considered as standard level. The thickness of 6 m seabed mud (-10 m to -16m from standard level) was replaced by sand first. The steel cylinders were inserted into the impermeable soil layer (-40 m) and then the seawater were pumped. The PVDs was inserted from –8 m up to -33 m and the sand was added up to +4m to improve the soft ground by dewatering preloading. The settlements at three typical sections, east section of the island which has deepest burial depth of tunnel (section 1), central section of the island (section 2) and west section of the island which has thickest soft clay layer (section 3), were measured during stage the soft ground improvement. The 3D finite difference method was used to simulate the construction process of the fast-constructed artificial island. The fluid-mechanical interaction method and equivalent hydraulic conductivity is used to predict the degree of consolidation. The settlement curves predicted by numerical method are compared well with the measured results in the field up to 150 days. The numerical results show that the long-term settlements (2400 days) of sections 1, 2 and 3 reach to 2.74 m, 2.91 m and 2.80 m, respectively. The residual settlements after two years of finishing the tunnel construction (1550 days) are 1 cm, 12 cm and 10 cm, respectively. The settlement rate and final settlement of artificial island calculated by the present method using one-dimensional consolidation theory are smaller than the measurement values in the field and the values predicted by numerical simulation. So the predicted settlement results by present method need to be modified according to field data, and numerical simulation method should be used to predict the long-term settlement.

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It is proposed engineering method for calculating the settlements of foundation bases at long-term nonlinear deformations soils, which is based on the method of layering with the spatial summation of the stress-strain state of the soil mass, regime of loading and duration of loading. Volume strain in time presented according to the theory of the hereditary creep as the sum of deformations of volume and the shape considering the interference.

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During installation of prefabricated piles in saturated clayey soils, excess pore water pressure is generated around the pile shaft and tip. The induced excess pore pressure is important to evaluate the stress state variations in clay and the subsequent pile bearing capacity. The main objective of this paper is to present a finite element numerical model to simulate a mini-cone installation (representing pile) and subsequent pore water pressure dissipation with time. The effect of OCR on soil stress state is also investigated. The numerical model is validated using the results of a physical model in which a mini-cone is penetrated into a consolidation chamber containing saturated clay. The results show that higher OCR develops less excess pore water pressure during installation. It is shown, however, that radial and vertical effective stresses as well as the coefficient of lateral earth pressure increase with increasing OCR during the excess pore water pressure dissipation process.

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Currently, the serious land subsidence disaster frequently occurred in China, leading to the growing and increasingly serious environmental impact and social harm. However, the high-speed railway is very strict with the track regularity and the control standard of foundation settlement, especially for uneven settlement. During last two years, the continuous observation and theatrical analysis is carrying on, and the results indicates that a pier in the high speed railway bridge presents a cyclical abnormal change law of floating in the rainy season and sinking in the dry season for 22 bridge foundations, and the variation law is consistent with the variation rule of the underground water level. The maximum of floating and sinking are23mm and 16mm, separately, and the variation range of the underground water level are from 11.2m to 30.8m. Based on the general finite element program ABAQUS, the three dimensional finite element model is established, in order to study the interaction between the underground water level and bridge foundation. The two types of piles, such as friction piles and column piles, are considered, then the influence law of the variation of groundwater level on the foundation settlement was discussed, and characteristics of the stress field and deformation field were revealed, which was verified by actual measured data, the results show that the friction piles affected by groundwater level change is significantly obvious than that column pile. Finally, the practical suggestions were proposed for the operation and maintenance of the high-speed railway.

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A high speed railway foundation with a thick top sand layer overlying a thick muck layer was treated with three methods respectively: both the sand layer and muck layer being treated by pre-stressed concrete pipe pile with a geogrid on pile top (PP foundation), only the muck layer being treated by jet grouting pile (JP foundation), and the sand layer being treated by dynamic compaction (DC foundation). Based on in-suit test data measured during construction of the railway embankment, settlement characteristics of the foundation were analysed. The results show that when choosing treatment method, not only the load level and foundation geological feature should be paid attention to, but also treatment aim must be considered; treatment method suitable for buildings to control total settlement might not be effective for embankment only to control post-construction settlement (PCS). DC foundation could only eliminate settlement of the sand within effective depth of dynamic compaction treating, so it was not suitable for the case whose treatment aim was controlling PCS. JP foundation, whose settlement during construction was large while the PCS was close to that of PP foundation, was efficient for the case with treatment aim of controlling PCS but might not be effective for the case that needs to control total settlement. PP foundation, whose settlement during construction and PCS were both small, as compared with JP foundation, just increased the project cost by increasing pile length to treat the sand layer for controlling PCS, and whose long-term stability of settlement depending on the durability of the geogrid is less reliable because the sand layer still remained loose.

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This paper investigated the similitude law for strip footing resting on cohesionless soils. 2D finite element analyses were employed to estimate the ultimate unit bearing pressure of strip footing in three different conditions: laboratory model test under 1-g, centrifuge test under n-g, and full scale test under 1-g. The Hardening Soil model was used for cohesionless soil to account for the increase in shear strength and stiffness with depth. Based on the numerical results, the axial unit bearing pressure-settlement curves were collected. The ultimate unit bearing pressures and settlements for three simulations were compared, and stress scale ratio and geometric scale ratio were drawn such that ultimate unit bearing pressure in full scale test could be estimated from laboratory test results

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The city of Arkhangelsk has the complicated geological conditions, particularly wide spread occurrence of soft ground such as peat and mud. The average annual atmospheric temperature is about +0.8°C and that enables the seasonal frost penetration up to 1.8…2.2 m. Usually the frost penetration causes damages to low-rise buildings, road paving, and pipelines. But the authors unexpectedly found in the process of their practical activities deformations of a building supported by 18 meter piles which were caused by the frost heave of a mud. The building is a cooling house designed for fish storage at the temperature of -22…-24°C which has been operated since 1985. It was found by drilling boreholes that the mud under the center of the building was frozen at the depth from 3.8 to 8.1 m. The floor uplift reached 18 cm, the inner columns uplift - 13 cm and the building was taken out of service. The numerical simulation data for 29 years of the building operation period performed by the Geostudio software correlate quite close with the data obtained by drilling the boreholes. The achieved experience may be useful for construction of ice rinks, cooling houses as well as for regular not heated storage buildings. As for the latter buildings located in the regions with the average annual atmospheric temperature about 0°C the frozen ground layers may continue and their thickness may increase for several years.

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