In August 2024, at the construction site of a housing project in Changsha, Hunan, a Xiaxing Heavy Industry JBMF1000 integrated drilling-and-pile-planting machine stood tall and upright, continuously repeating the processes of guide-hole mixing, pile lifting, and pipe pile implantation. The entire sequence of actions was efficient, smooth, and completed in one continuous flow. The integrated machine's combined drilling-and-planting frame structure enables precise alignment, ensuring high concentricity during pile planting. At the same time, the equipment features a one-touch leveling function, effectively solving the main problem of inclined and under-driven precast piles caused by loss of verticality control, thereby facilitating efficient and high-quality construction of the mixing-and-pile-planting project in Changsha.

According to drilling exploration, the site strata of this project consist of artificial fill (Qml), Quaternary alluvial deposits (Qal) of clay, rounded gravel, and sandy cohesive soil, Quaternary residual deposits (Qel), and Late Yanshanian (γ) granite.

The construction environment of this project is relatively complex, with adjacent buildings and residential areas nearby, and relatively high requirements for environmental protection and construction noise, which traditional construction methods cannot satisfy. Based on the above construction environment factors, the pile foundation of this project adopts the mixing-and-pile-planting method, with pile lengths of 22–26 m, cement mixing pile diameter of 700 mm, and core pipe piles using Jianhua 500 mm thick-wall ultra-high-strength pipe piles, with the rounded gravel layer as the pile foundation bearing stratum, and a characteristic value of single pile bearing capacity of 3000 KN.

The Xiaxing Heavy Industry JBMF1000 integrated drilling-and-pile-planting machine has good construction process stability, high construction efficiency, and a high degree of quality assurance, and has been unanimously recognized by the supervision unit, general contractor, and owner. During the construction period, multiple design institutes, general contracting units, and foundation construction companies in Changsha, Hunan, organized experts, leaders, and technical personnel to visit and inspect the site, and gave high praise and recognition to the construction quality and efficiency of the Xiaxing integrated drilling-and-pile-planting machine.

Advantages of the mixing-and-pile-planting method:

1. Low project cost: equal depth for drilling and planting: the drilling/planting depth error is controlled within (50 mm), high concentricity (error 10 mm), verticality (error 0.3%), and the drilling-to-planting conversion time is short, ensuring that the pile is planted in place before the cement soil initially sets, so that the geological bearing capacity and the bearing capacity of the precast pile body can achieve the best match, and the strength of the core pile body can be fully utilized. Compared with cast-in-place piles with the same bearing capacity requirements, it greatly saves project cost.

2. Controllable pile quality and high formed-pile quality: high-strength pipe piles are factory-prefabricated, ensuring pile quality. At the same time, the composite foundation process is adopted, and the pile body and pile joints are protected by cement soil, giving the entire pile high corrosion resistance; the implantation process can achieve no damage to the pile body, while the pile top elevation is controllable, with no need for pile cutting, providing multiple guarantees for high bearing capacity of the pile foundation.

3. Green and environmentally friendly construction: pile planting relies on self-weight implantation, with no soil squeezing effect, and does not affect surrounding pipe networks and other building facilities. Construction produces no noise from hammer driving and does not affect the lives of surrounding residents, and no exhaust emissions pollute air quality. Slurry discharge is reduced by 70% compared with cast-in-place piles, making it green and environmentally friendly with good social benefits.

4. High construction efficiency: one set of equipment completes the entire construction process of equipment assembly, drilling and mixing, pipe pile lifting, and clamping pile planting, avoiding time delays caused by frequent relocation of multiple pieces of equipment, making construction fast and efficient.

5. High degree of equipment intelligence: an intelligent high-precision control system is adopted, and key construction quality elements are recorded and monitored throughout the entire process, with a sound quality credibility system established, making the whole process visible, controllable, preservable, and traceable, comprehensively ensuring construction quality.‍
　　Applicable strata for mixing-and-pile-planting: