Study On Dimension Optimization Of Grout Fully-Length Achoring Threaded Steel Bolts

Currently, the amount of anchor engineering in underground projects is increasing, and the utilization rate of bolts is greatly improved with the continuous development and utilization of underground space. A large number of underground projects are all beginning to use full-length pre-stressed anchoring technology for supporting. However, due to unreasonable design of the bolt, resulting in difficulty on the construction of the anchor, limiting the promotion and application of the full-length pre-stressed anchoring technology. Therefore, it is the key to optimize the design of bolts support and improve the anchoring system that studying the effect of bolt profile configuration on anchoring performance.Based on the load transfer mechanism of the anchoring system, the anchoring performance of the bolt itself is enhanced by optimizing the bolt profile configuration. It is assumed that the bolt, grout and surrounding rock are all elastic materials. Under the influence of bolt transverse rib parameters, it is used to study the displacement change regularity of full-length adhesive grouted bolt, grout, and jointed rock mass in detail that the method of combining theoretical solution with numerical simulation, which are as follows:1. A large number of the latest research results at home and abroad on the dimension optimization of the anchor were collected and sorted out, the basic types and basic working principle of the bolt were introduced, and the load transfer mechanism of full-length adhesive grouted bolt anchoring section was highlighted. According to the characteristics of the interaction between anchor-grout and surrounding rock, a new theoretical calculation model was established through considering the influence of bolt transverse rib parameters and the current theoretical calculation model of full-length adhesive grouted bolt.2. Based upon the establishment of the new theoretical analytic model, the problem was solved by using the boussinesq equation and the stress change equation, the displacement formula of the bolt, grout and jointed rock was deduced, and the displacement solutions of the anchor,grout and surrounding rock were obtained under different transverse rib parameters. According to the specific calculation example, the displacement distributions of the anchor with different transverse rib spacing, transverse rib height and transverse rib width under the fixed load were compared and analyzed.3. The finite element software ANSYS was used to simulate and analyze the tension process of different transverse rib parameters bolts.The displacement contours of anchor, grout and jointed rock mass with different transverse rib parameters were obtained. Through comparing the theoretical analytic solution with the numerical solution,the displacement change regularity of anchoring section of different transverse rib parameters bolt was summarized, and some reasonable values of the related geometrical parameters of the anchor were put forward, which provided a reliable theoretical basis for the design,construction and anchoring calculation of the bolt.