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Lateral displacement of pile foundation is crucial to the safety of an overall structure. In this study, a numerical simulation on the lateral displacement of pile foundation under stacking loads was conducted to determine its relation with different influencing factors. Simulation results demonstrated that stacking loads at the pile side mostly influence the lateral displacement of pile foundation. The lateral displacement of pile foundation increases by one order of magnitude when the stacking loads increase from 100 kPa to 300 kPa. Other influencing factors are less important than stacking loads. Lateral displacements of the pile body and at the pile top can be reduced effectively by increasing the deformation modulus of surface soil mass, reducing the thickness of soft soil, and expanding pile diameter. Our analysis indicates that a nonlinear relationship exists between the lateral displacement at the pile top and the pile diameter. The lateral resistance of the pile body can be enhanced by coupling the stacking load along piles and the axial force at the pile top. An actual large-scale engineering project was chosen to simulate the effects of postconstructed embankment on lateral displacement and axial force of bridge pile foundation under different construction conditions and to obtain the lateral displacement of the pile body and the negative frictional resistance caused by soft soil compression under stacking loads. On the basis of the calculated results, engineering safety and stability were evaluated, and a guide for the design and construction was proposed.

Cracks are a type of damage often present in earthen sites, which have a particular influence on the structural performance. Cracks constitute preferential paths for rainfall infiltration, directly moistening the rammed earth and substantially reducing its mechanical properties. Therefore, the repair of cracks is an important part of the protection and reinforcement of earthen sites. Calcium carbonate is one of the main components of the tabia. The use of microbially induced carbonate precipitation (MICP) to repair and protect the tabia is not only environmentally friendly but also compatible with the substrate. In this paper, a crack-repair method dominated by MICP is proposed to repair the cracks of the tabia, and the repair effect is evaluated by experimental methods. First, the influencing factor test of MICP and the reinforced soil column test were carried out to determine the suitable parameters for repairing cracks, including the concentrations of bacteria and cementation reagent, filled soil particles and the number of grouting cycles. Then, the pre-damaged tabia samples were repaired using the suitable parameters, and the repair effect was verified. The results showed that when the crack width is 5 mm, the average flexural strength and shear strength recovery ratios of the specimens after MICP repair were 79.92% and 88.54%, respectively, showing a very satisfactory repairing ability. However, the recovery ratio tends to decrease as the crack width increases. In addition, the static contact angle test results showed that the MICP not only repaired the crack but also enhanced the hydrophobicity of the crack. MICP technology can be used as an effective method to repair cracks in the tabia.

Rain erosion is one of the most important factors causing the weathering of ancient clay roof tiles. Weathering damage generally proceeds from the surface to the interior; thus, protecting tile surfaces is an effective method to resist weathering. In this study, the microbially induced carbonate precipitation (MICP) technique is used to form an anti-erosion layer on the surfaces of tiles. Next, the applicability of MICP for tile surface erosion control is examined in the laboratory by the static contact angle test, capillary water absorption test, Karsten tube test, durability test, acid resistance test, water vapour permeability (WVP) test and colour change test. Moreover, the effect of the concentration of bacteria and cementation reagent on the surface erosion control is analysed. The test results show that MICP can significantly improve the water resistance of tiles by changing the microstructure of the surface. Higher concentrations of bacteria and cementation reagent allow the sediment layer to provide better protection; however, this effect is not linear. The concentration threshold reduces the positive effect of the bacterial concentration on the water resistance of the sample surface. The MICP protection layer offers favourable durability with little negative impact on the air permeability and colour of the sample. The use of an MICP protection layer can effectively relieve the weathering of ancient clay roof tiles.