Research On Optimization Arrangement Of Anti-Floating Bolts In Changdao Huicheng Project

The anti-floating anchor is a common underground structural component of construction engineering.At present,most of the anti-floating design schemes adopt a uniform planar arrangement.After the completion of the anchor construction,a large number of anchor joints extending out of the ground will be formed in the construction site,which will not only cause great trouble to the waterproof construction outside the basement floor.At the same time,the excavating machinery lacks sufficient running space,which affects the working environment and working efficiency of the cleaning machine.With the advent of the current rotary-expansion head bolt technology,the pull-out resistance of the anchor is constantly refreshed.Based on the Long Island Huicheng project,the paper optimizes the past anti-floating anchor uniformity scheme to the centralized arrangement of a small number of enlarged head anti-floating anchors under the independent foundation caps by utilizing the high pull-out characteristics of the enlarged head bolts.The number of anti-floating anchors also enables the site to meet the operational requirements of the cleaning machine.In order to improve the optimal design scheme,the research on the optimization of the design parameters of the head and single anchor,the group anchor effect and the weakening measures were carried out.The main research was carried out to expand the ultimate pullout force of the head bolt and to enlarge the head bolt spacing to the group anchor effect.The solution and other aspects are based on the previous results,and the economic analysis and comparison are made.The main conclusions are as follows:Through the in-situ test,the failure characteristics of the anchor rod drawing process and the ultimate anchoring force of the single anchor under different lengths of the enlarged head are obtained,and the ultimate pullout force and the enlarged head length of the enlarged head bolt are analyzed and analyzed according to the experimental data.The relationship is P = 161.6 + 81.4L(P is the expansion head ultimate pull resistance,L is the extended head length).By establishing the numerical model of the single anchor of the enlarged head bolt,the variation trend of the soil displacement field during the bolt drawing process is obtained.It is found that the bolt pullout force increases with the length of the enlarged head,the normal anchoring section and the diameter of the enlarged head.Increase,within a certain range,the effect of expanding the length of the head against the pull force is most significant,followed by the expansion of the head diameter,the impact of the ordinary anchoring section is minimal.Through the establishment of the enlarged head bolt group anchor model,the change trend of the overall pullout force of the group anchor and the development model of the soil displacement field under different anchor spacing and dislocation length are analyzed.It is concluded that the anchor spacing increases with the anchor spacing.The overall ultimate pullout force is increasing,the influence of group anchor effect is gradually weakened,and the concept of group anchor effect coefficient is introduced.When the anchoring distance is smaller,the group anchor coefficient is more obvious.The dislocation arrangement is more economical and reasonable than the dislocation arrangement.At the same time,the misalignment arrangement length is 1 time and the head length is the most economical and efficient.The economical analysis of the uniform distribution plan and the centralized optimization plan through three aspects of engineering quantity,construction cost and construction period,and found that the centralized arrangement scheme has greater economic benefits.The increase in the cost of the water-resistant plate reinforcement is not significant compared to the increase in the cost.