The key to the construction of plastic-steel sheet pile retaining walls lies in ensuring “precise positioning, standardized driving, and strict quality control.” We employ a proactive approach throughout the entire process to ensure the stability of the retaining structure and guarantee the safety of the excavation work. Prior to construction, we must thoroughly review the engineering geological survey report to clarify geological parameters such as silty clay and medium-density sand layers. By considering the excavation depth and the distribution of surrounding buildings, we determine the model, length, and embedment depth of the plastic-steel sheet piles, ensuring that the overturning safety factor is no less than 1.3

During the preparation phase, we must level the construction site, clear debris and obstacles, and lay temporary access roads to ensure smooth passage for the pile-driving equipment. We must perform precise surveying and layout work, using a total station to determine the axis of the pile positions and set up guide frames. We ensure these guide frames are securely installed and meet verticality standards to provide precise guidance for driving the plastic-steel sheet piles. Simultaneously, we must inspect the quality of the plastic-steel sheet piles, discarding any piles that are deformed, damaged, or have damaged interlocking joints. We will clean and lubricate the interlocking joints, applying grease to reduce driving resistance and ensure tight pile connections

During pile driving, we use a hydraulic vibratory pile driver, adjusting the excitation force and driving speed appropriately to maintain a rate of 0.8–1.2 m/min. We pause for 10 seconds every 3 meters of penetration to release pore water pressure. Throughout the driving process, we assign dedicated personnel to monitor operations continuously. We use two total stations to measure inclination in both directions in real time, promptly correcting the pile’s verticality to ensure deviations do not exceed 1/300. We operate according to the principle of “continuous pile driving on a pile-by-pile basis” to ensure tight interlocking of the pile joints and prevent disengagement or misalignment. After driving the piles to the design elevation, we promptly verify the pile cap elevation, controlling the error within ±20 mm

Upon completion of pile driving, we immediately conduct a quality inspection to verify indicators such as pile verticality, embedment depth, and joint tightness, with any non-compliant areas rectified promptly. Concurrently, we install waist beams and steel bracing, strictly adhering to the “brace first, then excavate” principle. We apply prestressing to 1.1 times the design axial force and maintain pressure for 5 minutes to lock the system, ensuring uniform stress distribution across the entire support structure. Throughout the construction period, we regularly monitored excavation settlement, pile displacement, and deformation of surrounding structures. Upon detecting any abnormalities, we immediately halted construction and implemented reinforcement measures, maintaining strict adherence to safety protocols at all times to ensure the smooth progress of the excavation work