The Application And Study Of Rock Bolt Foundation In Wind Power Foundation Engineering

The rock bolt foundation has been applied in the foundation of Wind energy turbine in mountain area due to its good performance of anti pull, economical and environmental friendly, safety and serviceability. However, in extreme loading condition, the load-bearing mechanism is complex and its damage mechanism is not clear. Besides it lacks mature theoretical guidance in the design of rock bolt foundation. In this paper, supported by Yantai inland wind turbine foundation engineering, a research on the design and application of rock bolt foundation in the project of wind turbine foundation has been done, by using the method of comparison design and numerical simulation. At the same time, the calculation formula of ultimate bearing capacity of rock bolts is deduced, which is based on the upper bound limit analysis method. The main research contents are as follows:First, by using two different designing method, a contrastive design in the wind turbine foundation has been made and the related design points been verified according to the specification requirements. The comparison results shows: the workload and the total cost will be significantly reduced by using the rock bolt foundation. And its flexural performance of foundation will be dramatically improved.Second, based on the basic principle of upper bound theory of limit analysis, allowable velocity fields of inverted cone failure mode and combining the modified Mohr-Coulomb criterion with a small but not zero tension cut-off, the calculation formula of ultimate bearing capacity of rock bolt is derived. It turns out that the results of upper bound method and field test are close by comparing them, demonstrating that the calculation method is reliable.Third, with the method of numerical simulation, the feasibility of rock bolt foundation design under different working conditions is verified, reaching the stress and settlement nephogram of the ground and foundation. Meanwhile, it studies the variation rule of the distribution curve of the rock bolt axial force and the bond stress influenced by the factors like the length and aperture of the anchor bolt.