TITLE:
A Slip-Force Device for Maintaining Constant Lateral Pressure on Retaining Structures in Expansive Soils
AUTHORS:
Yi Wu
KEYWORDS:
Expansive Soils, Retaining Structures, Slip-Force Device, Swell, Shrink, Bracing
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.11 No.3,
September
18,
2021
ABSTRACT: Expansive soils can pose tough issues to civil engineering applications.
In a typical year, expansive soils can cause a greater financial loss than
earthquakes, floods, hurricanes and tornadoes combined. Various means have been
studied to tackle problems associated with expansive soils. The majority of the
methods are based on treatment of the soils. While the methods may be effective
in some cases, their limitations are also obvious: The treatment normally
involves complex processes and may not be eco-friendly in the long run. In many
cases, the effectiveness of the treatment is uncertain. A retaining system that
maintains a constant lateral pressure is proposed, which consists of three
components: the retaining sheet, the slip-force device and the bracing column.
The retaining sheet bears the pressure exerted by expansive backfills and is
not embedded into the soils. Placed between the retaining sheet and bracing
column, the slip-force device permits displacement of the retaining sheet but
keeps the force on the sheet and the bracing column constant. The governing
equation of the motion of the piston in the slip-force device is derived and a
numerical simulation of a practical case is conducted based on the derived
governing equation. Numerical results show that as the expansive soil swell, the
spring force will increase and the piston will move accordingly. When the
pressure of the oil in chamber reaches the
open threshold of the unidirectional relief valve, the valve will open and the
spring force and the oil pressure in the chamber will keep constant. The results
also show that some parameters, such as damping ratio, have very slight
influences on the device behavior, say 2 × 10-6 or even 4.8 × 10-9.
Theoretical and numerical studies prove the effectiveness of the proposed
retaining system.