基于流体体积法的劈裂注浆有限元分析

Volume of fluid method based finite element analysis of fracture grouting

劈裂注浆作为一种有效的土体加固方法,其理论研究落后于工程实践。提出了基于弥散裂缝模型和流体体积法的劈裂注浆有限元分析方法,并通过ABAQUS二次开发编写劈裂注浆有限元程序。数值分析结果能与室内试验较好吻合,验证了有限元算法的合理性。在此基础上研究了注浆孔埋深和注浆流量对劈裂浆脉形状的影响。结果表明,劈裂注浆过程可分为起劈和劈裂发展两个阶段。当劈裂浆脉扩展到模型边界后,继续注浆会引起注浆压力的大幅提高和已有浆脉宽度的增加。随着注浆孔埋深的增加,浆脉分支减少,长度减小,宽度增加,劈裂浆脉形状的主要控制因素从土体参数的随机性变成大小主应力值的差异。注浆量一定的情况下,注浆速率越大,劈裂浆脉长度越短,宽度越大,注浆终压也越大。研究为劈裂注浆的工程应用提供理论支撑。

Fracture grouting is an effective method for soil reinforcement, yet the theoretical studies are far behind engineering practice. Using secondary-developed ABAQUS, a finite element model of fracture grouting is proposed based on the smeared crack model and VOF(volume of fluid) method. Results of FEM analysis are in good agreement with the laboratory tests. The effects of grouting depth and injection rate on the grout vein shapes are then investigated. The results show that fracture process can be divided into two stages: fracture initiation and extension. When the grout veins reach model boundary, higher grouting pressure is needed to increase the width of grout veins. With the grouting depth increases, the grout veins have less branches, reducing length and increasing width. The main factors affecting the shape of grout veins change from randomness of soil properties to the difference between major and minor principle stress. For given injection volume, higher injection rate results in shorter and thicker grout veins and higher grouting pressure. The research provides theoretical support for engineering applications of fracture grouting.