Centrifuge performance of LCSM wall reinforced pile-supported wharf subjected to yard load-induced marine slope soil movement

Lattice cement soil mixing (LCSM) walls are constructed to relief the marine slope soil movement that will trigger failure of the pile-supported wharf, the structural performance and pile-soil interactions after the LCSM implementation are major concerns. This paper investigated motion modes, load-displacement relations, soil and pore pressures, and bending moments of pile-supported wharfs with LCSM walls subjected to yard load-induced slope soil movement via centrifuge modeling. Results showed that the LCSM wall tilted to compress the soil and pile, inducing the tilting of the wharf. The lateral structural displacement was effectively restricted by the LCSM wall compared with that of a nonreinforced wharf, but the LCSM wall was not superior to the other lattice wall type with legs in limiting the lateral structural displacement, and the deep LCSM wall worked better at larger soil movement. The rear piles were evidently affected by slope soil movement and were compressed in the middle part. Soil pressures generally increased with increasing yard loads, whereas their distributions were deeply affected by different LCSM wall depths. Pore pressures were greater around the tilting LCSM wall because of larger soil shear areas but dissipated when soil movement stopped. Bending moment distributions indicated evident waterside curvatures in rear piles, whereas waterside curvatures occurred in the upper part and landside curvatures occurred in the lower part in front and middle piles, the effects of LCSM wall types and depth on bending moment distributions were tremendous.     

Capacity and failure mechanism of monopile-wheel hybrid foundation in clay-overlaying-sand deposits under combined V–H-M loadings

Innovative monopile-wheel hybrid foundations are proposed to enhance the lateral load and moment capacities of monopile for offshore wind systems. This paper presents a comprehensive numerical study on the bearing capacities of this hybrid foundation in clay-overlaying-sand soil conditions under combined V–H-M (vertical-horizontal-moment) loadings. Numerical models are generated and validated by comparing with laboratory experiment results and available centrifuge testing data on similar foundation systems. Parametric analysis is then carried out to quantify the effects of potential influencing factors on the failure mechanisms and bearing capacities of hybrid foundations, including the hybrid foundation geometry, soil properties, upper clay thickness, height of the lateral loading and pre-vertical load. It is found that in clay-overlaying-sand deposits, the hybrid system manifests totally different failure mechanism compared with that in uniform soil deposits. The thickness of the upper clay layer (T_c/L), within the practical range of T_c/L = 0.1–0.7, has a significant influence on the failure patterns and the bearing capacities of the hybrid system, and the proportion of bearing capacity provided by the pile and wheel is determined by the ratios of D_w/L and L/D_p. In addition, the failure envelopes in the V–H-M space manifests that the failure envelopes are shrank with the increase of the normalized vertical resistance, V/V_ult, which is highly related to the clay layer thickness (T_c/L).