# Enlarged Head Pressure-Dispersed Anchor Cable for Foundation Pit Engineering Purposes
## 1 Introduction
The simulated values of the ground anchor load transfer mechanism provided a reasonable prediction for the project. [PERSON] et al. [14] studied the fluid-structure coupling effect in the simulation of the deep foundation pit and found that the settlement displacement of the fluid-structure coupling model was larger than that of the nonfluid-structure coupling model. Through experiment and simulation, [PERSON] et al. [15] found that the anchorage section of pressure-dispersed anchor cable is mainly compressed, and the maximum compressive stress occurs at the embedded plate. [PERSON] et al. [16] deduced the calculation formula of ultimate pullout force suitable for the enlarged head anchor cable, which solved the problem of the high precision requirement of the parameter value in the standard method. [PERSON] et al. [17] proposed a geotechnical framework, which can further analyze the internal stress of soil. The anchor solids of a tension anchor cable are easily destroyed due to the stress concentration inside the anchor solids, but the pressure-dispersed anchor cables disperse the total tension load to each anchor cable element and transfer the tension of the anchor cable into the pressure of the anchor solid of the anchor cable element to the soil mass [18]. Additionally, the stress is more reasonable, and the non-sticky anchor cable is easy to recover [19]. [PERSON] found that pressure-dispersed anchor cable has a better anti-vibration ability than the tension-concentrated anchor cable [20]. Therefore, in recent years, there has been a huge surge in research on pressure-dispersed anchor cables. According to the stress distribution characteristics of pressure dispersive ground anchors, [PERSON] et al. [21] developed a new type of bottom-expanding construction equipment, thus expanding the effective diameter of the anchor body and improving the anchoring capacity and saving project costs. [PERSON] et al. [22] carried out performance tests on the pressure-dispersed compression anchors in clay. Field tests and calculations showed that post-grouting increased the diameter of effective anchors and improved pull-out resistance of anchors. [PERSON] [23] carried out numerical simulation research on the new pressure anchor cables and observed that the distribution of axial stress and shear stress of the anchor solid was reasonable, which overcame the transmission defects of the traditional anchor cables. Summarizing the above research results, we can see that the current research on the anchor cable mainly focuses on three aspects. One is to focus on the internal forces, such as the shearing stress of the grout-soil interface and the axial stress of the anchor solid, while there is relatively little research on the end resistance at variable sections. The stress of the anchor cable is shown in Figure 1. Second, the study on the enlarged head anchor cable is mainly focused on the tension-type rather than the pressure-dispersed type. Third, with respect to foundation pit support, there are few studies considering the fluid-structure coupling, but the influence of seepage on the foundation pit support cannot be ignored. Therefore, using engineering examples along with the FLAC3D numerical simulation, the force mechanism of the enlarged head tension-type and pressure-dispersed type anchor cables and the support effect of the two types of anchor cables are compared and analyzed in the present study. Enlarged head anchor cable is a kind of anchor cable commonly used in foundation engineering. First, an anchor drilling rig is used to drill a hole. After the drilling is expected to be completed, high pressure jet grouting is inserted at the end of the anchorage to expand the hole to 6 m. The length of the hole is 6 m. Then, the prefabricated steel strand and steel casing are inserted. Finally, the grouting is divided two times until it flows out of the cement slurry.