Abstract:To investigate the influence of construction technology and parameters of rod-extended deep mixing piles on the pile formation quality, a typical soft soil site along the Liansu Expressway was selected for field trial piling. Ground improvement was conducted using rod-extended deep mixing piles with varying construction parameters and methods. Following pile formation, standard penetration tests (SPT), core recovery tests, and 28-day unconfined compressive strength (UCS) tests were conducted to evaluate pile quality and identify the optimal construction method and parameters. The test results showed that a top-down construction method, with a blade rotation speed of 60r/min, drilling and lifting speed of 1.0m/min, and a cement content of 80kg/m, was well-suited for marine silty soil in Lianyungang. In practical engineering applications, construction parameters should be combined and matched based on site-specific geological conditions and the empirical formula for the number of mixing passes per soil layer. Ensuring that the soil at any point within the reinforcement zone is mixed at least 25 times contributes to achieving better pile formation quality and ground improvement effects. Although conventional deep mixing piles typically demonstrate higher pile quality due to the absence of complex processes such as rod coupling and decoupling, rod-extended deep mixing piles still meet the required technical specifications. Therefore, under construction conditions with height limitations, rod-extended deep mixing piles can serve as effective substitutes to conventional piles, meeting strength requirements and achieving satisfactory engineering performance.
