The characteristics of ram extension pile and soil compaction pile united ground improvement are compared with that of post grouting pile by rotary drilling and soil compaction pile;the influence of the loess collapsibility on bearing capacity of pile-foundation is analyzed.

Study on modifying coefficient of end-bearing resistance of large diameter belled piles;

The results obtained by this method fit well with the field test results, and the potential bearing capacity of large diameter belled pile can be utilized fully, so it can be used as a reference in engineering design.

Research on axial bearing behavior of large diameter piles;

Using the ABAQUS software,the static load testing results of two large diameter piles have been simulated by the three-dimensional finite element numerical method.

This paper introduced the principle of sliding micrometer in test of large diameter pile body, and compared it with traditional method and indicated that t his kind of method has the merit of accurate test result and can appraise the quality of pile body.

The large diameter piles (LDPs) not only have stronger bearing capacity with less deformation, but also have some other advantages: flexible in application, simple in computation, convenient for construction, and economical in materials consumption, etc.