| The PTC pile(Pre-stressed Tubular Concrete pile) with cap applied in expressway deep soft soil ground, enhances the ground bearing capacity effectively and reduces the settlement of ground, which is one kind of fruitful composite ground processing technology and obtains remarkable economic and social benefits. Although composite ground of the capped PTC pile has been developed maturely in practice, its academic research trails the project practice. Its bearing capacity and settlement calculation is imperfect, specially the pile-soil stress ratio research is at the start stage, its computational method mainly uses other pile-soil stress ratio method. Along with the development of this kind of composite ground, we need the corresponding theory to match the technology. According to above problem, this paper study and analyze the mechanism of it by spot experiment, theory analysis and FEM analysis. Main content are as follows.1. The full-scale test of the capped PTC pile composite ground has been conducted, including four group of single pile with cap test and one group of double-pile with cap composite ground test. Through the test data, the bearing capacity, the settlement transmutation, the rule of the load transmission and pile-soil stress ratio are analyzed.2. Based on the distortion pattern analysis of the capped PTC pile composite ground under the embankment, in consideration with pile-soil interaction situation, this paper deducts pile-side friction distribution and analytic solution of compression quality of the reinforcement area from mechanics angle, thus obtains the analytic expression of the pile-soil stress ratio.3. Finite element procedure Plaxis is used to analyze the pile-soil stress ratio and the rule of the load transmission. With this procedure, this paper analyzes the changing rules of the pile-soil stress ratio, the axial strength and the pile-side friction when the length of the pile, the distance of the pile and the size of the cap change. During the use of this procedure, this paper establishes the appropriate interface between the pile and the soil to describe contact characteristic, and chooses the appropriate soil model, enables the precision of the finite element result. |
