【摘要】 随着陆地资源紧缺，水下建造成为工程开发的必经之路。现阶段水下混凝土的研究较为系统，尚无针对水下3D打印混凝土的研究见诸报道。水下智能建造可数字成型、免模施工，有利于推动深地深海工程的发展，3D打印混凝土为其核心技术。目前面向水下混凝土和陆地3D打印混凝土的设计方法尚未综合考虑水下智能建造工艺和服役环境的特殊性。因此，本工作根据力学性能、可打印性能、水下工作性能建立了水下3D打印混凝土配合比优化设计流程，针对水胶比、矿粉掺量、砂胶比、细骨料级配、絮凝剂掺量、触变剂掺量等材料参数开展序列化试验设计和试验研究。结果表明：成型后混凝土28 d抗压强度随水胶比、矿粉比例和砂胶比等参数的增长呈现降低趋势，其中水胶比影响最显著，其次为矿粉比例，砂胶比和絮凝剂掺量对材料强度的影响较小。基于试验数据和鲍罗米公式提出了具有较高拟合精度的水下3D打印混凝土配合比设计模型。综合考虑打印成型混凝土强度和水下不分散性确定絮凝剂最佳掺量为胶凝材料质量的2%。确定流动度在165～190 mm范围可保障水下打印建造，基于DIC监测信息以砂胶比、触变剂掺量以及细骨料级配为基本变量建立3D打印混凝土建造期竖向变形时变预测模型，可用于水下3D打印混凝土建造稳定性控制。本工作首次面向水下智能建造建立了3D打印混凝土配合比优化设计流程，提出了水下3D打印混凝土强度设计模型和建造期竖向变形预测模型，为水下智能建造提供理论依据和工程借鉴。优化后水下打印成型混凝土28 d抗压强度达到55 MPa，水陆强度比达到93.9%，可满足水下智能建造结构的性能要求。更多还原

【Abstract】 With the shortage of land resources, underwater construction has become the necessary way for engineering development. At present, theresearch on underwater concrete is relatively systematic, but there is seldom report on the research on underwater 3 D printing concrete.U nderwater intelligent construction can be digital forming without formwork and can promote the development of deep-sea engineering, in which3 D printing concrete is its core construction technology． Currently, the design methods for underwater concrete and land 3 D printed concrete lack technical pertinence to underwater intelligent construction process and service environment. In this paper, the optimization design process of underwater 3 D printing concrete mix proportion has been established according to the mechanical properties, printability and underwater working performance. A serials of experimental studies were designed and carried out considering the influences of water binder ratio, mineral powder dosage, sand binder ratio, fine aggregate gradation, flocculant and thixotropic agent content. The results showed that the 28 d compressive strength of printed concrete decreased with the increase of water binder ratio, mineral powder ratio, sand binder ratio and other parameters. The water binder ratio has the most significant effect, followed by the mineral powder ratio, and the change of sand binder ratio and the flocculant agent content have little effect on material strength. Based on the experimental data and Boromir formula, an underwater 3 D printing concrete mix proportion design model with high fitting accuracy is proposed． Considering the strength and underwater non-dispersibility of printed concrete, the optimum dosage of flocculant is 2% of the mass of cementitious material. The fluidity range of 165—190 mm can ensure the construction requirement of underwater printing. The time-varying vertical deformation prediction model is established with consideration of sand binder ratio, thixotropic agent content and fine aggregate gradation as basic variables, which has reliable accuracy and can be used to control the stability of underwater 3 D printing concrete construction． It is first times to systematically study the underwater 3 D printing concrete, establish the 3 D printed concrete mix proportion optimization design process for underwater intelligent construction, and put forward the underwater 3 D printed concrete strength design model and the vertical deformation prediction model during construction process, which provides theoretical basis and experimental reference for underwater intelligent construction. The 28 d compressive strength of optimized underwater printed specimen is up to 55 MPa, and the water land strength ratio reaches93. 9%, which can meet the performance requirements of underwater intelligent construction structure.更多还原