Reasonable selection of action combinations is an important prerequisite for ground and foundation design. To determine action combinations based on limited states design for excavated foundations of transmission pole and tower

force characteristic of foundations was analyzed. According to the main three action conditions on foundations of transmission pole and tower

bearing and failure characteristic and easier exceeding limited states of structural system including excavated foundation and ground were studied

and action design combinations of the ground-foundation system were provided. The failure characteristic of excavated foundations bearing too much load is brittle under uplifting or overturning conditions

and fundamental combination controlled by variable load are adopted as required by ultimate limit state design. The relationship curves between load and displacement of excavated foundations are non-steep-fall under downward force condition

based on serviceability limit state design

characteristic or quasi-permanent combinations should be mainly used.