Model Tests and 3D Simulations of Deep Cement Mixing Wall Reinforced with Prestressed Steel Tubular Truss

Abstract

Steel trusses have desirable bending performance; accordingly, a new type of stiffen deep cement mixing (SDCM) wall，namely deep cement mixing wall (DCM) reinforced with a prestressed steel tubular truss, is proposed in this paper. Its performance is studied via model tests and 3D finite element simulations of cement–soil composite beams. The deformation, stiffness, and crack distribution characteristics of different cement–soil composite beams are compared and analysed, and the stiffness contribution of the steel truss and cement–soil to the composite beams is elucidated. According to the test results, the ultimate deflection of the cement–soil composite beam reinforced with prestressed steel tubular truss is reduced by approximately 25% compared with a cement–soil composite beam reinforced with an ordinary steel tubular truss, and it is reduced by approximately 29% compared with the prestressed steel tubular truss. The results show that the steel truss bears approximately 70% of the load, whereas the cement–soil bears the remaining 30% of the load. Prestressing can effectively delay the development of cracks in cement–soil composite beams, thus greatly improving the overall stiffness and support capacity of composite beams. Analysing the loading process of composite beams via the finite element model revealed that the bearing characteristics of steel trusses are largely uniform: in the cement–soil composite beam or steel truss alone. Accordingly, along with the results of the numerical simulation analysis, it is proved that the steel truss is critical to improving the flexural capacity of composite beams, and the load sharing ratio of the prestressed steel truss is higher than that of an ordinary steel truss. The prestressed steel truss reinforced composite beams have better flexural performance than an I-beam.