Because the materials used in the above-mentioned flexible piles are stricter than DDC piles, such as gravel piles and sand piles, they cannot be used locally, and the project cost is bound to be higher. DDC pile engineering materials have strong adaptability and can be obtained from local materials, which reduces transportation costs and construction costs.
The pile reinforced by DDC pile is very dense due to the powerful compaction effect of high-energy and high-pressure tamping and dynamic punching, smashing and squeezing, and it is slowly released after receiving huge tamping energy, constantly exerting lateral squeezing force on the soil around the pile. However, the soil around the pile is subjected to strong lateral squeezing stress, which is slowly released after the pile is completed, which has great lateral restraint and "hugging" effect on the pile, making the pile have the characteristics of semi-rigid and semi-flexible pile. For layered foundation or uneven soft and hard soil, piles will form a ball string state during construction compaction, which is beneficial to the close "bite" between piles and soil around them, and increases the friction of side walls, so that reinforced piles and soil between piles form a close whole. The treated composite foundation is not only uniform in stiffness, but also remarkably improved in bearing capacity. The pile-soil stress ratio is generally 3-5 times.