Question

1. what is the quality problem often met in the bored piles with the hole being supported by the mud

2. introduce the different types of the enclosure structure for excavation of basement. what are the advantages and the disadvantages of the steel bracing compared with RC bracing

Answer 1

1.

• Sinking of holes in bored piles in soft clay or water bearing sand causes settlement in adjacent structures
• Lateral movement into the piles and uplift also causes damages to the pile
• Flow of ground water into the bored piles causes damages to the pile bored,it can be prevented using Steel bracing and using bentonite
• Collapse of sides of piles are common is soft and loose soil,should be prevented using casing

2.

• Zone excavation method
• Top down bottom method
• Island excavation method
• Anchored excavation method
• Full open cut method
• Bracing excavation method

Steel bracing is provided to increase the strength and durability of concrete structures especially to resist lateral loads such as earth quake in high rise buildings.

Steel bracing are provided either using nuts and bolts or using jacket using suitable epoxy, Steel bracing increase stiffness and strength of structural members

Steel bracing have advataadv over RC bracing such as light weight reducing dead weight,easy installation and maintainance,Long lasting and provide better performance compared to RC bracing

RC bracing are cheap compared to steel bracing .It increases the dead weight of the structure and size of members and difficult to maintain and provide