Study on the Influence of Length Variation of Tension-Compression Section on Anchorage Performance of Composite Anchor

Anti-floating is one of the important engineering problems faced by deep foundation pit construction. At present, anti-floating anchors are often used to balance the buoyancy of groundwater on structures. But the tensile anchor has the problems of local stress concentration and shallow critical anchorage depth. Therefore, a new type of tension-compression dispersed composite bolt was designed. Through the field test, the relationship between the length change of the tension-compression section of the composite bolt and the anchoring performance of the bolt was analyzed and compared with the tensile anchor. The results show that the composite anchor can effectively prevent the shear failure of the first interface of the anchor. With the decrease of the length ratio of the tension section to the compression section (the ratios are 5, 2 and 1, respectively), the ultimate bearing capacity of the anchor increases gradually, which are 1.17, 1.22 and 1.44 times of the tensile anchor, respectively. The steep drop of the load-displacement curve gradually disappears, and the structural ductility is better. Increasing the length of the bearing section within a certain range can more effectively call the strength of the lower soil layer of the anchorage section, and the critical anchorage depth of the anchor is moved down, finally the side friction resistance is higher.