Research On Force Mechanism And Design For Recyclable Anchor Cable

With the rapid development of urban underground buildings,foundation engineering plays an important role in the city.In the pit retaining engineering,the traditional pile-anchor support structure will be permanently buried in the soil after the work was completed,which will not only bring pollution to the surrounding environment,but also become the main obstacle of underground construction.In addition,traditional anchor cables still have many problems such as large construction radius,limited construction space,and non-recyclability in actual projects.In contrast,the recyclable anchor cable structure can not only avoid pollution and damage caused by the anchor cable to the underground environment,but also greatly improve the bearing capacity of the anchor cable,which effectively promotes the sustainable development of urban underground space.This thesis analyzes and summarizes the existing recyclable anchor cables,and proposes a new recyclable anchor cable structure.The force mechanism of the anchor cable was systematically analyzed,and the feasibility and practicability of the new anchor cable was analyzed through theoretical formulas,experimental analysis,and finite element modeling.The main work is as follows:(1)Classify the stress mechanism and recovery characteristics of various anchor cables.Based on the empirical formula proposed by national standards,analyze the stress mechanism of the new anchor cable and its impact on the surrounding soil.(2)Based on existing research results,an indoor test plan had been proposed.In the early stage of the test,the soil direct shear test and the CFRP cable pull-out test were completed.The comparison between the new expansion head anchor cable and the traditional expansion head anchor cable pull-out test was made,and the stress characteristics and advantages of the new anchor cable were analyzed.The results show that the force mechanism of the new type of enlarged head anchor cable is better than that of the traditional enlarged head anchor cable;The pull-out bearing capacity of the new enlarged head anchor cable is 1.2 times that of the traditional enlarged head anchor cable.(3)The above indoor test was numerically analyzed by finite element software,and the force and deformation data of the anchor cable were obtained,and the test data were compared and analyzed.The results indicate that the stress characteristics of the finite element model of the anchor cable are basically consistent with the experimental anchor cable stress.(4)By using the finite element software to simulate the actual size anchor cable,the theoretical empirical formula of the new enlarged head anchor cable was proposed.(5)Changed the geometric conditions such as the anchoring depth of the enlarged end of the anchor cable,the spacing between the enlarged ends,the length of the enlarged end anchoring section,and the number of enlarged ends,and analyzed the impact of the above conditions on the actual engineering anchor cable’s pull-out bearing capacity.The results show that the changes in buried depth and number of enlarged heads have a significant impact on the anchor cable,while the distance and length between enlarged heads have a relatively small impact on the bearing capacity of the anchor cable.