To determine the ultimate load capacity of drilled shaft socketed into rock under axial compression loading, it is necessary to predict both the ultimate side shear resistance and the base resistance based on field load test or/ and laboratory tests. In geotechnical engineering there are several methods proposed the relationship between rock properties (the unconfined compressive strength) and the ultimate side shears resistance and base resistance. This paper presents the review of design methods of ultimate side shear and base resistance for rock-socketed pile. These empirical functions depend on the socket type and the range of the unconfined compressive strength of rock.

The twin shear strength criterion has been proposed to consider the intermediate principal stress effect on the rock mass strength. The unified rock mass strength criterion could consider the intermediate principal stress effect on the rock mass strength. The unified rock mass elasto-plastic material model is implemented in ABAQUS user interface. As a case for study, the stability analysis of Dongjusi railway tunnel within hard rock mass is studied using the unified rock mass strength material. For comparison, the Hoek-Brown empirical strength criterion is also chosen for the rock mass material modeling. The computation results show that the plastic zone calculated using the unified rock mass strength criterion is smaller than that using the Hoek-Brown empirical strength criterion. The railway tunnel lining structure is designed according to the unified rock mass strength criterion and greatly makes use of the rock mass potential strength, which decreases engineering cost.

Static load tests were carried out with Osterberg method on 3 bored piles formed in Liao River Bridge. Bearing capacity, base resistance and frictional resistance were obtained before and after base grouting. Based on the test results, the ultimate bearing capacities of piles were increased for 14.74%~43.87%, that of pile bases were increased for 89.57% ~ 163.49% and the frictional resistances were most increased for 31.20%. The pile bearing behavior was improved. Not only base resistances were improved after grouting, but also frictional resistances were improved by bettering the characteristics of soils and interfaces between piles and soils. After grouting, pile base resistance ratio of pile bearing capacity increased, and some frictional piles changed into end-bearing frictional piles. The frictional resistance of lower pile increased more than that of upper pile after grouting. The slurry penetration height of base grouting had a certain range, which was affected by quantity of mortar intrusion, grouting technology, grouting pressure and geological structure.

Indoor model experiments were made to study loads on single pile under the wave-current flow. Take three different velocities of the current and three different diameters of piles in the experiments to get the variations of loads. Drag and lift forces were measured by a two-component balance. Analysis on experiment results shows that, both drag force and lift force increase with the increase of the pile diameter and the current velocity. The drag coefficient Cd increases with the increase of Kc number until Kc researches 12, when Kc is more than 12, Cd decreases with the increase of Kc; while the inertia force coefficient Cm decreases with the increase of Kc, when Kc is more than 12, Cmchanges little. And the lift coefficient shows no correlation with the Kc number.