Obstructions can be difficult, because you often do not know they are there until you begin to install a deep foundation. Helical piles cannot install through obstructions; however, here we highlight the different options you have for dealing with obstructions while installing helical piles. One of the benefits of helical piles is that you do not have to abandon the pile. In most cases, it can be removed and reinstalled (unlike other deep foundation options).
On many construction projects, soil borings are not completed due to the property owner wanting to reduce costs or, quite simply, being unaware of the need to obtain soil strength data for foundation design. During the installation of CHANCE® Helical piles, monitoring torque can provide real time data defining underlying soil strength and its load capacity. As a helical pile is installed (screwed) into increasingly denser/harder soil, the resistance to installation (called installation energy or torque) will increase. The higher the torque, the higher the axial capacity. In most projects, the installation torque increases with depth, and the capacity of CHANCE helical piles can be determined at the time of installation. Regardless of whether the pile is being installed in clay or sand soil, the torque to correlation factor (Kt) for each shaft size, is multiplied by the effective installation torque (T), resulting in the ultimate capacity for each pile. The standard equation for ultimate capacity is Kt * T. The torque correlation factors for CHANCE helical piles can be found in the CHANCE Technical Design Manual-4th Edition. The effective torque is the average torque taken over the last 3 feet of installed depth, measured in 1 foot increments.
Any contractor can tell you that a structure is only strong as its foundation. Deep foundations transmit the structure’s load to soils that are deeper in the ground. A deep foundation is used when a shallow foundation is not possible, not practical, or will not carry the load, such as in weak, unstable, or expansive surface soils. Proper site preparation and installation is key to the success of any job – starting with the foundation.
When building a new home, short-term decisions usually include what floor tile to use in the kitchen or which coverings to put on the living room bay windows. Few homeowners think about which type of foundation offers the best long-term stability.
With residential remedial foundation repair becoming a greater concern, the CHANCE® helical pile was developed in the mid-1980s and was issued a helical underpinning methods patent in 1992. This all sounds well and good, but the question remains: Why are helical piles so effective for remedial foundation repair?