Numerical Simulation Of Floor-GFRP Anti-floating Anchor Under Uplift Action

GFRP anti-floating anchor is a new composite material anti-floating anchor system, including the internal anchorage in the foundation slab and the external anchorage in the rock and soil. Mechanical properties of GFRP anchor itself, such as elastic modulus and low shear strength, decide that stress distribution between the two is bound to be different compared with steel anti-floating anchor system. Mechanism of GFRP anti-floating anchor needs to be further research and comparative analysis when subjected to buoyancy effects. This paper completed a series of numerical simulations and comparative analysis by the Abaqus software, and further reveals the stress and strain distribution of GFRP anti-floating anchor system. The main works and research are as follows:1. By establishing spatial axisymmetric model of straight GFRP anchor anchored into the concrete floor of different lengths(420 mm and 840 mm), to study the distribution of stress of GFRP anchor in the concrete floor, and the simulation of bond-slip and experimental results were compared. The results showed that:(1) Under low loads, the rod axial stress negative exponential distribution, and the axial stress increases as the load increases; Under a high level load, the scope of maximum axial stress expand.(2) Bolt shear stress under low loads negative exponential distribution, as the load increases, the shear stress peak value appearing and moving to the depths. And shear stress rod ends decreases.2. For the features of GFRP anti-floating bolt anchoring in weathered granite, and based on the existing site pull-test, this paper established space axisymmetric models of different anchor length(3 m and 5 m), and completed the numerical calculation. Get the stress distribution, anchoring mortar stress distribution, and the impact on the surrounding rock mass of GFRP anti-floating anchor of different anchor length, and summary analysis its rules and characteristics, and complete comparative analysis of GFRP anti-floating bolt of different anchor length, and further reveals the anchor properties of the internal anchorage. The results showed that:(1) Axial stress is decreasing in the depth direction, and as the load increases, the axial stress increases, and as the depth increases, amplitude decreases.And peak shear stress increases with load increases, and gradually moves to the depths.(2) Under the same load level, the greater the anchorage length, the smaller the depth axis stress transfer.The smaller anchorage length is, the greater peak shear stress is, and closer to the orifice.3. Based on the results of existing pull-out test, this paper completed the numerical Simulation of Reinforced anti-floating anchor, which diameter is 28 mm and length is 3 m. Get the stress distribution, anchoring mortar stress distribution, and the impact on the surrounding rock mass and were compared with GFRP anti-floating anchor of the same diameter and anchoring length. It reveals their similarities and differences, and the impact of the bolt stiffness on stress distribution. The results showed that:(1) Under the same conditions, axial and shear stresses showed approximately the same distribution law which anchorage length is 3m and diameter is identical.(2) Under the same conditions, the larger the modulus of elasticity of bolt is, the greater the depth of stress stress axis transfer and the smaller shear stress peak is and the more uniform stress distribution is.4. Through establishment of spatial axisymmetric numerical model of floor-GFRP anti-floating anchor system, and applying different groundwater buoyancy on the concrete floor, this paper obtain the displacement and the stress distribution of the system. The results showed that:(1) When not considering the bond of concrete and rock, the internal anchorage and the external anchorage follow their own stress distribution; Rod axial peak stress occurs at the interface of the floor and rock, and there are two rod shear stress peak points.(2) Displacement of the floor-GFRP anti-floating anchor system is mainly generated by the internal anchorage, and in contrast, the slippage of the external anchorage is smaller.