Abstract:
Long-term mining of coal resources has resulted in the formation of a large number of goaf areas. In addition, with the rapid development of wind power, a green energy source. Land for engineering and construction is becoming increasingly constrained. Some wind turbines have had to be considered for construction on better goaf wind farms. However, there are significant safety risks associated with the construction and operation of wind turbines at goaf sites. Studying the catastrophic mechanism of wind turbine foundation is an important way to solve such scientific problems. Firstly, a set of dynamic loading test device for wind turbine foundation was developed at the goaf site, with dynamic load output realized within a 1% error. Verification of the feasibility of power loading for wind turbine foundation modeling tests at goaf. A two-dimensional similarity test model with a geometric similarity ratio of 1∶100 has been developed. Theoretical equations were used to calculate the wind loads at rated wind speed and extreme wind speed once in a century. And two sets of similar modeling tests under different operating conditions were carried out. Based on the results of model tests, the variation of the settlement, inclination angle and base pressure distribution of the fan foundation with the number of loading times under the rated wind speed condition was analyzed, the catastrophic mechanism of wind turbine foundation under extreme wind speed conditions is described. Research shows: Settlement deformation of wind turbine foundation at rated wind speed is closely related to the number of loadings, the settlement of the foundation increases with the increase of the number of loadings, the settlement rate of the foundation is inversely proportional to the number of loads, the maximum settlement of the foundation is closely related to the mechanical properties of the foundation soil. The overturning and emptying of the foundation under extreme wind speed conditions is caused by the increase of the load class, the settlement and inclination of the foundation are relatively small when the previous load class is low, when the load increases to a certain extent, the foundation begins to produce a more obvious settlement, as the load continues to increase, voiding begins to appear at the bottom of the foundation. The basal pressure on the edge of the windward side of the foundation is 0, and the base slope reaches 80% of the allowable value, it has a great impact on the safety of wind turbines. Under the two working conditions, the earth pressure of the goaf foundation decays rapidly with the increase of depth. Soil pressure on the windward side of the foundation is almost zero at a depth of 8 m, it shows that the horizontal dynamic load has a great influence on the shallow rock strata in the goaf. Under the two working conditions, there is a certain safety distance between the load influence depth of the wind turbine and the caving fault zone. The wind load does not cause the foundation activation in the goaf, but it is necessary to consider the residual deformation of the goaf site and other possible activation deformation.