The Study On Soil-Nailing Wall-Pile Composite Supporting System And Monitoring For Deep Foundation Excavation

The standards for deep foundation pit become higher and higher as large number of high-rise buildings and underground projects were constructed. The supporting type choosing, the mechanics analysis of support structure and the study on stability of deep foundation pit are important problems in geotechnique field. This paper relying on the Yuling Xidu foundation pit project in Chengdu city, systemically studied the soil nailing wall-pile construction and using monitoring technology to control the message of stability of foundation pit real time, through feed back technology dynamically appraised the stability of foundation pit slope, gave guidance to the construction process in time to ensure the safety.1 Firstly this paper analyzed the geology engineering conditions of the ground, discussed the principles and gist of foundation pit supporting design, separately calculated the project when supported by piles in row or soil nailing wall, studied the soil nailing wall-pile supporting mode and the load distributing form. Then design the supporting project of Yuling Xidu foundation pit. The space between every pile was increased from 3m to 4.5m, when soil nailing wall was used.2 This paper discussed the purpose, significance of monitoring and the principles, content of monitoring design. Then expatiated the main items and instruments of foundation pit monitoring. Basing on these above, designed the monitoring system of Yuling Xidu foundation pit, and study the pre-warning guide line and emergent blue print.3 This paper carefully analyzed and studied the monitoring data, guided the construction process by monitoring message feedback through the whole excavation and supporting. The monitoring results shows that the soil nailing wall-pile multiple supporting mode designed in this paper can guarantee the safeness of pit, and proved the feasibility of design.4 Deeply and comprehensively analyzed the monitoring information, discussed the relationship between displacement and excavation , studied the displacement characteristics of piles in row, mechanics characteristics of soil nail and steel reinforcement, distributing characteristic of earth pressure. In the end, used FLAC3D to build a partial three-dimensional numerical model, simulated the evolution of displacement during the excavation, and compared it to the monitoring results.