Dissertation > Excellent graduate degree dissertation topics show

Behavior of the Composite System of Deep Mixing and Concrete Pile Wall at Deep Excavations in Soft Soils

Author: HeQiang
Tutor: MaJianQin
School: Chang'an University
Course: Bridge and Tunnel Engineering
Keywords: Deep mixing concrete pile walls composite supporting system optimization Finite element method
CLC: TU753
Type: Master's thesis
Year: 2011
Downloads: 92
Quote: 0
Read: Download Dissertation

Abstract


Deep excavations are one of the key problems for the design and construction of a cut-and-cover tunnel in urban areas. The stability of the excavations in soft soils, and the choice and optimization of the supportting system for the excavations always have a heavy influence on the time schedule of construction and the magnitude of environmental disturbance due to the construction of an underground structure. Based on the analysis on the mechanical behavior of a composite system of deep mixing and concrete pile walls, a few paramters, which have a strong potential of influencing on the supporting system behaviors, are discussed, to provide technical support for the optimization of the supportting system and construction control.The results of case histories show that Increasing system stiffness and embedment of the wall into a stiff layer are key factors in limiting the deformations of supporting system and retained soils at deep excavations in soft soils. Deep mixing may have the diplex fuctions of both ground improving and limiting the deformations.The results of the analysis, with finite element code of Plaxis, on the composite system at deep excavations in soft soils show that:(1) of a composite system of deep mixing and concrete pile walls, the function of the waterproof curtain of deep mixing piles behind walls, to some extent, is effective; (2) it is not an effective measure of increasing supporting capacity of the system to increase the diameter of concrete piles; and (3) the supporting capacity of the system can be significantly improved by improving the ground below excavating bottom.A case study shows that the construction time schedule may be optimized by reducing the numbers of strut of the composite system of deep mixing and concrete pile walls at deep excavations in soft soils, provided that the deformations of the retained soils are not strictly limited. It is noted that the factor of safety of the excavations are and therefore significantly reduced under this situation, and the difficulty of the risk control of the construction increases accordingly. As the only one strut is set at the top of the walls, the bending moment of the lower part of the walls is larger than that of the excavations with two struts. The increased moment due to reducing strut may leads to wall cracking at the level of 1.5 m above formation level.

Related Dissertations

  1. Analysis of Bearing Capacity of Cement Deep Mixing Column in Soil Improvement,TU473.1
  2. Study of Settlement and Loading Capacity of Deep Cement-soil Mixed Pile Composite Foundation in Yellow River Delta Salt-water Area,TU473.1
  3. Study on Deterioration and Durability of Deep Mixed Cement-soil Pile in Yellow River Delta Salt-water Area,TU473.1
  4. Study on the Design Parameter and Application Effect of In-depth Agitation Pile Anti-seepage Wall,TV543.8
  5. Experimental Study on Enhancing Effect of Soft Soil for Express Railway with Deep Mixing Pile,U416.1
  6. Research & Application on the Technology of Long Screw Jet & Mix Cement Pile Curtain,TU753.3
  7. The Settlement Control Study of the Deep-mixing Compound Foundation,TU473.1
  8. The Submarine Structural-acoustic Radiation Optimization Analysis Based on Multidisciplinary Design Optimization Theory,U674.941
  9. The Submarine Structural-acoustic Radiation Optimization Analysis Based on Multidisciplinary Design Optimization Theory,U674.76
  10. Study and Application on Deep-mixing Pile Composite Ground and Curtain for Cutting Off Water,TU753.3
  11. Second Order Sensitivity for Evolutionary Structural Frequency Optimization: The Concept & Application,O342
  12. The Big Water-cement Ratio Soil-cemet Deep Mixed Pile Foundation Construction Technology and Acceptance Standard Research,TU753
  13. The Application of Anchoring and Shotcreting Technique with Deep Mixing Piles,TU753.3
  14. Based on the two sides to the gradual optimization of topology optimization methods,V214.19
  15. Research on Calculation Theory and its Application of Deep-mixing Pile in Composite Ground,TU472.36
  16. Multi-Objective Dynamic Optimum of Gantry Container Crane Structure System,TH213.5
  17. The Optimization Design of Molar Restoration,R783
  18. Topology Optimization and Finite Element Analysis on a Truck Frame,U463.32
  19. Cushion airbag cushion landing numerical simulation and design optimization studies,TP391.9
  20. Development of the Mechanism of Continuously Changing Sideslip Angle in High Speed Wind Tunnel,V211.754
  21. Container ship structural analysis and design studies,U674.131

CLC: > Industrial Technology > Building Science > Construction > The project and the type of work > Foundation engineering
© 2012 www.DissertationTopic.Net  Mobile