Civil Project Abstract Secant Pile Construction Technique:Over the last few decades construction of retaining walls in urban areas has grown significantly, as a result of territorial and economical development of the cities. In most cases, retaining walls are deep structures with the existence of groundwater level because urban areas are often at a few meters above sea level. Furthermore, construction of retaining walls in cities, introduce special problems as a result of being directly in touch with urban elements and citizens.
In situ pile retaining walls are very popular due to their availability and practicability. There are different types of pile walls contiguous (intermittent) bored pile construction, (spacing between the piles is greater that the diameter of piles).
In these conditions, for deep borings and with the existence of groundwater level, diaphragm walls and secant pile walls are the only feasible retaining walls in urban areas. Secant pile walls are usually used in hard ground, where it is not possible to install diaphragm walls, and in rocks, and it is technically possible to install secant pile walls in a extensive range of grounds.
Advantages and Disadvantages:
Noise: comparatively secant piles methods are more adaptable. Wall plan geometry: As site values increase, the pressure to use all available space within basements has become intense. Sites are often sandwiched between existing buildings, and walls are placed in close proximity to adjacent structures or roads.
The main disadvantages of secant pile walls are:
1. Verticality tolerances may be hard to achieve for deep piles.
2. Total waterproofing is very difficult to obtain in joints.
3. Increased cost compared to sheet pile walls.
For temporary works, a hard-soft secant constitutes a perfectly satisfactory structure. For permanent structures the suitability of the technique demands critical evaluation in the particular site circumstances and structural requirements. Cased secant construction methods provide a high degree of security when working in granular soils adjacent to heavily loaded foundations or adjacent structures. Hydraulic diaphragm wall cutters are high production machines and require a large site, both to work efficiently and for their related service plant and back up facilities.
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