Application Of Oblique Brace System Using Supporting Piles And Cap To Deep Excavation

More and more deep excavations are adjacent to the existing building basement. The construction space of traditional pile-anchor brace system is limited. With flexible arrangement, oblique brace supporting system can be not affected by the land red line and around buildings. Moreover, compared to the integral bracing structure, the oblique brace supporting system makes it excavate more conveniently and can speed up the construction progress, shorten the construction duration. It can also make it cost lower and save a lot of money.The paper uses numerical simulation methods to study the application of oblique brace system to deep excavation by large-scale finite element ABAQUS software. Firstly, the paper verifies that the methods、procedures and tools to establish deep excavation numerical model by ABAQUS finite element software are reasonable. Then it uses ABAQUS software to establish numerical model of oblique brace system using supporting piles and cap to deep excavation. And it compares numerical simulation results with project monitoring data. The numerical simulation results are the horizontal displacement of soldier pile and ground surface settlement outside excavation. The results indicate that the trend of numerical simulation results with the trend of project monitoring data is consistent. It shows that the method and results of numerical simulation to deep excavation are feasible. It verifies that the method and procedures of numerical simulation are reasonable by ABAQUS software for the oblique brace system using supporting piles and cap.In view of application of oblique brace system using supporting piles and cap to deep excavation, the paper mainly analyzes the mechanical characteristics of oblique brace and two supporting piles by ABAQUS software. And the paper makes the deformation of excavation by oblique brace system compare with it by horizontal strut. The results show that the oblique brace system has a significant effect on restraining the uplift of soil at the bottom of excavation. But the scope of restraining the uplift of soil is certain at the bottom of deep excavation(the horizontal distance from the soldier pile is about 23 meters at the bottom of excavation). Beyond the scope, the effect of restraining the uplift of soil is not obvious. The results also indicate that the horizontal displacement of soldier pile and ground surface settlement outside excavation by oblique brace system are larger than them by horizontal strut. However, the horizontal displacement of soldier pile and ground surface settlement outside excavation are satisfied with the warning value and controlling value of excavation. The oblique brace system can ensure the safety of deep excavation. Finally, it uses ABAQUS software to verify that the current method to design oblique brace is reasonable.The paper makes a further research about the geometric parameters of oblique brace system by ABAQUS finite element software. The parameters mainly contain the different position on the cap of the oblique brace, the different spacing between two supporting piles under the cap, the different connection forms(rigid connection and hinged) between the oblique brace and the cap and the different connection forms(rigid connection and hinged) between the oblique brace and the soldier pile, the different diameter of supporting pile under the cap. And it makes the application of oblique brace system on the different soil parameters. The paper makes some conclusions by analyzing the ground surface settlement outside excavation, the horizontal displacement of soldier pile, the uplift of soil at the bottom of excavation and the mechanical characteristics of soldier pile and supporting pile under the different geometric parameters of oblique brace system. And it can provide some useful references for the design and construction of the similar deep excavation.