Where retaining walls are of masonry construction, movement joints must be included. Failure to do so could lead to cracks in the retaining wall that weaken its structural integrity and could eventually lead to its failure.
Important points about retaining walls
Don't forget to include movement joints in the wall and use piers on either side to increase strength at the movement joint position.
Movement joints in internal walls are not normally necessary for single dwellings unless the walls are straight and unbroken and over 6m long, in which case the block manufacturer's recommendations should be adopted. This may include the use of bed joint reinforcement in the courses above and below window openings.
The basic principle for the design of the Retaining Wall is that the reinforced concrete stem and footing flexure and shear design strength must e at least equal to the factored moment and shears determined from the analysis. The wall stem is designed as a cantilever, fixed at the footing.
For counterfort walls, expansion joint spacing shall be a maximum of 32 feet on centers. For soldier pile and soldier pile tieback walls with concrete fascia panels, expansion joint spacing should be 24 to 32 feet on centers.
Expansion joints in walls at 30 m maximum intervals. (If the walls are panel walls between columns at not more than 9 m centres no joints are necessary.) Control joints over centre of openings may be given at half the spacing of expansion joints.
Some builders uses a thumb rule stating that the retaining wall's thickness should be at least one-tenth of the wall's height as a quick reference for residential applications. For instance, 0.4 feet (4.8 inches) of thickness might be the beginning point if the wall is 4 feet high.
Absolutely! Even a 2-foot retaining wall needs an effective drainage system. Without it, water can build up behind the wall, leading to pressure that might cause the wall to lean or even collapse. All walls need systems to manage water effectively, preventing damage over time.
Determining the Width: The Golden Rule
A good rule of thumb is that the width of the base should be about half the height of the wall. So, if you're building a 4-foot tall wall, aim for a 2-foot wide base.
A retaining wall can fail without tiebacks and anchors, leading to soil erosion, property damage, and even safety hazards. Tiebacks and anchors are particularly crucial for retaining walls that support large loads or are situated on slopes where the pressure from the soil is most intense.
Concrete expansion joints are particularly important where there have been consecutive concrete pours and are also useful when laying concrete within an area bordered by walls or buildings or if objects such as manhole covers need to be incorporated.
Longevity and Durability
One of the most appealing features of diamond block retaining walls is their impressive life expectancy. Thanks to their concrete composition and interlocking design, these walls can last 50 years or more with minimal maintenance.
In building construction, expansion joints are strategically placed gaps that allow concrete slabs to expand and contract without damaging the structure. They act as a buffer zone, absorbing thermal movement and preventing the formation of cracks and fissures.
The footing, or first row of your retaining wall, should be about 4 to 6 inches deep and about 12 inches wide, or twice the width of the block you are using. The blocks should sit about halfway into the soil.
Generally speaking, expansion joints should be no farther apart than 2 to 3 times (in feet) the total width of the concrete (in inches). So for a 4‑inch thick concrete slab, expansion joints should be no more than 8 to 12 feet apart.
The bottom layer of rebar usually is 3 inches above the ground, supported by rebar chairs or concrete bricks. It includes five lines of bars running parallel to the length of the wall. One line lies along the centerline of the footing and the others are spaced 8 inches on center from the adjacent bars.
The footing should be 16in wide (or more depending on you block depth) and 6-8in of compacted crushed gravel. The depth of the trench should also include the height of one full row of blocks which will be buried below the finished grade. So if your blocks are 6in tall, your footing trench should be 12-14″ deep.
As a general rule, we have written that the required distance between two walls for them to act inde- pendently must be greater than or equal to twice the height of the lower wall.
You may be wondering what the situation is when a retaining wall might be necessary – let's take a look! In most cases, a retaining wall is needed when the slope of the land exceeds a certain angle, usually around 4:1.
Hydrostatic Pressure and Wall Failure
When water isn't properly drained, it can accumulate behind the wall, exerting pressure on the structure. This pressure can prompt the wall to shift, crack, or even collapse. To avert such failures, it's crucial to have adequate drainage behind the retaining wall.
Base thickness = 1/8 of the height of the wall but not less than 12 inches. Stem thickness = 6 inches + ¼ inch for each foot of wall height.
Weep holes are a crucial component of retaining walls. The common function of retaining walls is to create a difference in level between the ground at the top and the area in front of the wall by supporting a height of retained soil.
Proper Installation: Layer and compact the base gravel to a sufficient depth, typically 4-6 inches, depending on the wall's height and the soil conditions. For the drainage rock, ensure it is placed behind the wall up to the same height as the wall itself.
Retaining walls are typically built between 3 to 4 feet tall. The typical height for most retaining walls is 3 to 4 feet.