地质聚合物加固软土的微-细-宏观多尺度研究

Geopolymer, a low-carbon and environmentally-friendly cementitious material with excellent engineering properties, has shown great application prospects in many areas. This project proposes to use geopolymer replacing energy-intensive cement for soft soil improvement from the viewpoint of energy conservation and environmental protection. The proposed project investigates the mechanical properties of the geopolymer-stabilized soil and reveals the underlying improvement mechanisms using a micro-, meso-, and macro-scale approach. First, the orthogonal experiments are carried out to investigate the factors affecting the strength and micro-characteristics of geopolymer-stabilized soil so that optimum material parameters for stabilization meeting the engineering requirements can be obtained. Second, the shear strength at different curing ages and long-term deformation characteristics of geopolymer-stabilized soil prepared by the optimum material parameters are studied via the direct shear and triaxial creep tests respectively, and the involvement of micro-scale characteristics of geopolymer-stabilized soil is also investigated. Third, static loading tests are carried out respectively on single pile and single pile reinforced composite foundation to study the mechanical properties of geopolymer mixing pile. Finally, meso-scale numerical simulations using discrete element method are carried out to link the micro-scale characteristics of geopolymer-stabilized soil to its macro mechanical properties. The proposed project intends to clarify the underlying mechanisms of how geopolymer strengthens soft soils from micro, meso, and macro scale levels. The outcomes of this project will further the understanding of the mechanical properties of geopolymer-stabilized soil and reveal the strengthening mechanisms. The success of this research will provide the scientific basis for industrial application of geopolymer for soft soil improvement.

地质聚合物是一种低碳环保、性能优异的新型胶结材料，其在众多领域显示出了巨大的应用前景。从节能环保的角度出发，提出以地质聚合物代替高能耗水泥进行软土地基处理。拟采用微观特征分析、细观数值模拟与宏观力学试验相结合的多尺度研究方法，对地质聚合物加固软土的力学性能和加固机理进行研究。通过正交试验，研究不同因素对地质聚合物加固软土强度和微观特征的影响，并获得满足软土地基处理要求的最优材料参数。通过直剪试验和三轴蠕变试验，研究最优材料参数条件下地质聚合物加固软土不同龄期的强度和长期变形特征，并分析其微观特征的演化；通过室内单桩和单桩复合地基静载试验，研究地质聚合物搅拌桩的宏观力学性能。通过细观离散元数值模拟，建立宏观力学性能与微观特征的关联。从微、细和宏观三个层面揭示地质聚合物加固软土的机理。研究成果有助于深入了解地质聚合物加固软土的力学性能和机理，为地质聚合物加固软土的工业应用提供科学依据。

课题组首先开展了地质聚合物固化软土最优材料参数的研究，分析了地质聚合物掺入比、碱激发剂浓度和养护条件等对固化土无侧限抗压强度的影响，得到了地质聚合物固化软土的最优材料参数。其次，在最优材料参数条件下，开展了地质聚合物固化土的力学性能研究，获得了固化土强度及变形随龄期的变化规律，提出了固化土强度随龄期增长的经验公式；开展了地质聚合物固化土的微观特征研究，得到了地质聚合物胶结物质和固化土微观形貌随龄期的演化规律，并通过细观组构与宏观特性的关联，揭示了地质聚合物固化软土的力学机制。最后，开展了地质聚合物搅拌桩处治深厚软土地基的模型试验与数值模拟，研究了地质聚合物搅拌桩复合地基的承载能力和变形特性，验证了地质聚合物搅拌桩加固软土地基的可行性和有效性。本项目的完成对深入了解地质聚合物固化软土的机制和促进地质聚合物固化土的工业应用具有重要价值。