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The bearing capacities of spudcan foundation under pure vertical (V), horizontal (H), moment (M) loading and the combined loading are studied based on a series of three-dimensional finite element analysis. The effects of embedment ratio and soil non-homogeneity on the bearing capacity are investigated in detail. The capacities of spudcan under different pure loading are expressed in non-dimensional bearing capacity factors, which are compared with published results. Ultimate limit states under combined loading are presented by failure envelopes, which are expressed in terms of dimensionless and normalized form in three-dimensional load space. The comparison between the presented failure envelopes and available published numerical results reveals that the size and shape of failure envelopes are dependent on the embedment ratio and the non-homogeneity of the soil.

The main structure materials of tunnel lining are concrete and steel, and the concrete frost damage is a typical degradation phenomenon of the tunnel linings in cold regions. Alkali-activated slag concrete (ASC) has a better freeze-thaw resistance, which can be used for tunnel lining in severe frigid regions. Freeze-thaw resistance, performance mechanism of ASC and microstructure were investigated by freeze-thaw cycle, X-ray diffraction (XRD) and Scanning electron microscope (SEM) analysis. The experimental results show that, ASC has excellent freeze-thaw resistance, and hydration products of ASC are mostly C-S-H, alkaline aluminosilicate. ASC has a good compact degree and uniformity of structure, and its high compressive strength also makes high freeze-thaw resistance. ASC may be selected as tunnel lining production materials in severe frigid regions because of the less reduction in the dynamic elastic modulus and mass loss of concrete.