Analysis of Deep Foundation Pit Pile-Anchor Supporting System Based on FLAC3D

Abstract

Relying on a deep foundation pit project in Beijing, using FLAC3D three-dimensional finite-difference software simulation combined with displacement monitoring data verification method, the deep foundation pit excavation and three-pile and two-anchor rod support system in anhydrous sand pebble stratum are systematically analyzed, and summed up the variation law of formation stress, internal force of soil nail, axial force of bolt, stress and displacement of pile in the process of excavation and support of deep foundation pit. The results show that during the excavation of the foundation pit, the maximum horizontal displacement of the sidewall is not at the top of the pile and the top of the slope but at a certain distance below the top of the pile. The axial force of the anchor rod is unevenly distributed along the length direction, the axial force of the free section is equal, the axial force of the anchoring section decreases in turn, and the prestress of the anchor rod spreads to the anchoring section after tensioning and locking. The soil-nailed wall is a passive force-bearing system, the force is small during the excavation and support process, and the axial force distribution along the length direction is large in the middle and small at the two ends. By analyzing the variation law of stress and deformation, the timeliness of the data in the construction process is improved, and an effective and reasonable case reference is provided for the informatization construction of simulated relevant working conditions.

Numerical Analysis of Bearing Capacity in Deep Excavation Support Structures: A Comparative Study of Nailing Systems and Helical Anchors

“…Their study shed light on the variables influencing the performance of the retaining structure and emphasized the need to limit lateral displacement during excavation. Similar to this, during the construction of a deep foundation pit, Sun et al [14] examined the behavior of a three-pile and two-anchor rod support system in an anhydrous sand pebble strata. Their investigation clarified the axial force distribution along anchor rods and the passive force-bearing property of soil-nailed walls, which advances our knowledge of the behavior of support systems in a range of scenarios.…”

Multi-Stage and Multi-Parameter Influence Analysis of Deep Foundation Pit Excavation on Surrounding Environment

“…Deep foundation pit engineering is a complicated engineering issue involving engineering geological conditions, climate conditions, surrounding construction environment, technical level, management level, and many other factors, so it has the characteristics of comprehensive and high risk [11][12][13]. During the construction of deep foundation pits in high-rise buildings and other projects, the supporting structure interacts with the soil to adjust their stress and deformation stably so that the soil inside and outside the foundation pit is stable or unstable.…”

“…The numerical simulation and analysis of foundation pit excavation are of great significance to improve the design theory and construction level of deep foundation pits. At present, many scholars have published relevant papers on foundation pit excavation [24][25][26][27][28], but some numerical simulations on foundation pit excavation mainly analyze the influence of foundation pit supporting structure, such as stress and strain of underground diaphragm wall and stress and strain of anchor rod and lack relevant research on the influence of foundation pit excavation on the surrounding environment [11,[29][30][31][32]. At the same time, some numerical simulation models of foundation pit excavation use two-dimensional models instead of three-dimensional models, which cannot analyze the overall situation of foundation pit excavation comprehensively and accurately [33,34].…”

Deformation Characteristics of a Deep Subway Foundation Pit in Hard Rock Strata under a Delayed Supporting Condition

“…Tough empirical analysis methods are precise in terms of analyzing deformations of a foundation pit, the corresponding analysis processes are usually of low efciency. Terefore, numerical analysis tools, such as FlAC 3D , Midas GTS NX, and PLAXIS3D, are usually adopted to calculate stresses and deformations of the foundation pits to be excavated for the purpose of increasing analysis efciency meanwhile assuring the analysis accuracy [12][13][14][15]. At present, most numerical investigations are focused on deformations of foundation pit in soil strata or soil-rock composite strata [16][17][18][19].…”