Specialist Advice & Difficult Sites
Because every site & situation is different, All Retaining Systems can provide specialist advice to provide a customized solution for your site. We have expertise in a range of situations including difficult terrain. We consult with engineers and geotechnical engineers to ensure that your project is completed safely and to the correct specifications.
In situations involving difficult terrain, we will remove rock, soil, trees, scrub and any existing structures. This can be done by small machinery including bobcats, excavators, dingo's or even by hand using pick shovels if needed (we are not afraid of hard work!). This is followed by temporary shorring to secure the area whilst the new retaining system is built.
Once the new structure is built, we will back fill and compact if needed. Other services include bitumen coating and weep holes if needed.
The gravity wall provides lateral support from its self weight and bearing pressure at the base.
Conventional limestone walls are the most common example in WA. It is essential that the bearing pressure, imposed by the base of the wall on the underlying foundation soil strata is acceptable and does not cause excessive rotation or settlement of the wall structure. It is also essential that the wall geometry and mass provide adequate resistance to sliding, as these walls do not typically incorporate any depth of embedment.
[Quoted from MA Woodward "Australian Geomechanics Vol 38 No 3 September 2003 – The Engineering Geology of Perth Part 1]
Another Analysis for Gravity Walls
It is vital that a detailed analysis of the geology of the site and any other influences are thoroughly assessed at the planning stage to ensure the right wall is used. Due to the huge gravitational forces that a wall is subjected to, along with the added complications of drainage systems, this can be a complex area that requires the right advice.
All Retaining Systems can investigate your particular retaining problem and provide the right solution for a successful outcome based upon engineering and geo-technical reports if required.
We can install a range of different retaining systems including limestone walls, double brick cavity, L panel pre-cast, H Beam double panel and post cavity filled plus other systems. We can also put a waterproof membrane at the back of the walls. This may be employed to ensure a successful, long term and worry free solution for a clients.
The process of designing a retaining system will require will essentially require determination of destabilizing loads or forces (eg. overturning moments, horizontal forces and or earth pressures on the structure and comparison with the restraining loads or forces that can be sustained by the retaining structure. An adequate (FOS) against the ultimate limit state of collapse or failure must be maintained. There are numerous engineering publications which define appropriate design methods for the various retaining systems that All Retaining Systems can provide to WA residents or commercial projects.
Preparation of Foundations
When we prepare foundations we ensure that we follow engineering designs where required. We will excavate the hole, working with the existing ground level and boundary pegs provided to us. We then get our bottom of wall (B.O.W) level and thoroughly compact and put water in the base so the ground hardens up sufficiently. Heights are then set with a laser followed by screeding of the ground base. We then start building. A proper start ensures a proper finish!
The importance of Draininage in Ensuring the Longevity of Your Wall
Poor drainage is one of the main reasons why almost 80% of retaining walls fail at some point so it is vitally important to ensure that the correct measures are taken to protect the wall and preserve your investment. This can be done through any or all of the following methods:
Backfilling - The term "backfill",means the soil or material situated behind a retaining wall. It is important to use clean fill behind the wall rather than just soil and materials found on site. Once clean fill has been brought in, it is acceptable to place soil from the existing site on top. If you are planning on landscaping the area on top and around the wall it is best to bring in clean landscaping soil to assist with vegetation. All Retaining Systems can supply this to you.
Perforated Piping - Another way to ensure adequate drainage of your retaining wall is through the use of perforated piping inside the base of the wall. In the event of heavy flooding and excessive watering, this can assist by providing somewhere for the water to escape and get channelled away from the wall. Without this system, water can collect behind the wall causing eventual wall failure through decay and weakening of the structure. To further assist with drainage, we can also use geocloth around the piping which is embedded in crushed blue stone.
IWeep Holes - Another way to divert moitsure away from your wall is to put a sufficient number of weep holes for water to escape. Consult with your contracter who can advise on the correct number and placement of weep holes neccessary for your particular wall.
With such an investment, it is always tempting for the property owner to cut corners, saving time and money but only to find it costing more in the long run when walls fail. Therefore it is important to take a few extra steps to ensure the longevity of your investment. By doing things right the first time, it actually costs you less in the long run.
These walls are called impermeable retaining walls which have a proper drainage system including weep holes, aggregate pipe and blue metal. This won't allow water to stay trapped behind and cause seepage through the face of the wall and cause the wall to weaken.