Technical considerations in building reinforced soil walls
Reinforced soil walls have proved highly popular in recent years and are produced wherever possible, taking the place of concrete-faced soil retaining wall systems.
Employed in a range of different environments, they bring significant advantages, both financial and environmental. Indeed, unlike concrete-faced soil retaining wall systems, they:
- are sustainable because they give a vegetated finish;
- are a great space-saving solution, with slopes as steep as 80° (compared to the 30-40° of natural soil embankments);
- result in less pollution given the smaller number of trucks required to carry construction materials;
- make use of the excavated earth for backfilling, provided it is compatible with stability standards, meaning no more material needs to be brought in;
- blend seamlessly with their surroundings once the slopes are grassed over, without becoming a blot on the landscape of our villages.
Whatever the case, before planning the work, there are a number of aspects and data to be taken into consideration.
Preliminary data needed
To start with, all essential technical information must be procured in order to be able to assess the feasibility of the project, such as:
- geological testing of the area on which the wall is planned to be built
- topographical surveys
- meaningful cross-sectional drawings showing the current condition
- geometry of the planned wall (face angle, height, division into tiers, slope on top)
- external loads applied to the structure (top loads in the event it needs to accommodate a car park or a road)
- what earthquake risk zone the area is in
- geotechnical properties (angle of shearing resistance, cohesion and density) of the earth behind the future wall, of the foundation soil, and of the backfill
- whether there are perched aquifers or seepage of a different nature.
At this point, the next step is to check design calculations using specific software.
Checking design calculations
Checking is performed to assess both internal and external stability. The following tests are carried out in the former case:
- reinforcement strength test, which assesses possible failure mechanisms and determines the spacing, length and tensile strength of the geosynthetics due to be laid
- pull-out test to check that the reinforcement applied does not break or slide out
- direct sliding test, to ensure there is no translational movement across the installation planes
- wrap-around test, to ensure that the length wrapped around the top of each individual layer is stable.
The checks to be carried out during the project’s execution to assess external stability consist in sliding, overturning, bearing capacity and global failure analysis.
Do you want to chat with one of our experts to find the solution that best suits your requirements?
We have 30 years of experience in the industry and can give you access to materials and solutions offering specific performance. Contact us!
Do you want to learn more about the full TeMa Geo Solutions product range for reinforced earth structures? Click here.
- Published in Drainage geocomposites and membranes, environmental, GEO, Geogrids, Reinforced earth structures, Reinforced earth structures - Drainage, Reinforced earth structures - Erosion control
Cycle and pedestrian paths: solutions to make them safer and more attractive.
Longer days, milder afternoons, a great desire to spend time outdoors and perhaps get some physical exercise, but also go to work and school or visit a friend… These are all good reasons for using, when available, cycle and pedestrian paths, possibly far from urban traffic.
The advantages of sustainable mobility
We are increasingly talking about environmental sustainability and the physical and psychological benefits of physical exercise:
- Less air and noise pollution caused by traffic.
- Reduced transport costs.
- Greater freedom of movement.
- Enhanced green areas in cities.
- Better quality of life by doing a bit of sport on a daily basis.
TeMa Geo Solutions for safety and urban benefits
‘Unequipped’ roads can be hazardous for those who choose to get around by bicycle: for this and environmental reasons, cycle and pedestrian paths are the ideal solution, as they are increasingly becoming part of local government mobility plans.
TeMa Geo Solutions offers all its experience by combining reinforced earth structures and their feature of being green, with cycle and pedestrian paths.
An embankment can be made or a road widened with its sides sloping at 65°/70° using the T-System (consisting of formworks, X-Grid PET geogrids and K-Mat FG Green erosion control mats as facing), thereby making the path safe and allowing a slope to turn green again. Making a slope green again provides a natural erosion control function: to encourage it, TeMa Geo Solutions recommends installing natural or synthetic mats. To make the structure stable, the T-System for reinforced soils adopted by TeMa involves using X-Grid PET geogrids.
Reinforced earth structures and drainage
For the extension works at the Serravalle Retail Park shopping centre in the Piedmont region, we helped the company choose the solutions to implement and assisted with verifications.
The area covering about 2,000 sqm required some intervention work regarding reinforced earth structures and drainage. In particular, we undertook the preliminary work for extension works dating back to 2016.
To the south-west of the building, the soil was secured and then surfaces were replanted with greenery.
Let’s see how this was done in more detail.
Type of intervention
In order to make the slope in front of the complex secure, the intervention work involved constructing reinforced earth structures in several banks, more specifically 3 modules of 6 m in height each.
In addition, to manage the water coming from the hydro-geographic basin situated upstream of the area, specific surface drainage works were carried out.
The solution from TeMa Geo Solutions
For the reinforced earth structure, 3 modules were constructed with anchorage lengths of 7 m and a strength of 110 kN/m provided by X-Grid PET PC 110 geogrids.
As for drainage, instead, a Membrana Nera Geo was used, the 8 mm HDPE studded membrane bonded to a filter nonwoven geotextile with a PE slotted tube at the base.
The drainage system was also installed at the horizontal contact points of each berm to prevent future water seepage into the reinforced earth structure.
Reinforced earth structures as noise barriers
Hearing the noise of traffic outside your window all day long is irritating and distracting and, in the long term, also harmful to your health.
This is why the WHO and a number of laws govern the use of noise remediation systems in cities: the Framework Law no. 447 of 1995 for Italy and the European Directive on Environmental Noise no. 49/2022. If the cause of the noise cannot be addressed, the solution is to install protective barriers. Various kinds can be used, but in this case we focus on reinforced earth structures that require specific measures, which we discuss here.
For example, the Pedemontana Veneta is a new toll motorway in Italy: nearly 100 km long. Almost entirely in operation in the north-east of the Veneto region, the main route of this motorway runs through a deep trench in order to minimise the ‘territorial’ and environmental impact on the surrounding area. This means that long sloping areas of reinforced earth can be found along the sides of the motorway, with rows of trees and hedges for 58.61 km and green areas covering 1,333,410 square metres of hedgerows, groves, grassy slopes and tree-lined meadows.
A focus on noise with much regard for the landscape.
What do reinforced earth noise barriers consist of?
For this type of embankment with its typical trapezoidal shape, earth is used that will be covered by vegetation over time. Geosynthetic reinforcements and geogrids are added to support the earth, which already has good compressive strength. These are inserted horizontally into the ground and develop friction and tension that stabilise the structure, increasing its resistance to stress.
The TeMa Geo Solutions offer includes the X-Grid Pet PVC range of geogrids, with different resistance values, which are ideal for all kinds of contexts.
Another aspect to bear in mind is surface erosion of the soil: to counteract this, synthetic geomats are applied, also with a mulching function to encourage the growth of grass cover, or natural fibre bionets.
Also in this case, TeMa Geo Solutions offers a wide choice ranging from Ecovermat F Grass and Ecovernet FJ to the K-Mat range.
Why use a vegetation barrier as a protective noise barrier?
A vegetation barrier has an unquestionable ability to limit the spread of sound waves: some of them are absorbed, some reflected and some deflected. As a result, the amount of sound waves reaching the receiver is greatly reduced and noise can be dampened by several decibels.
The advantages of a reinforced earth sound-deadening barriera
Creating reinforced earth structures brings considerable advantages:
- it costs less because you can often use earth available on-site
- no special maintenance is required other than regular trimming.
- it helps the environment and integrates with it: the use of vegetation also reduces vehicle emissions by absorbing CO 2 and purifying the air.
Controlled landfills and the importance of isolating them
Landfills for inert, non-hazardous and hazardous waste are governed by specific laws in each country, which set out precise regulations on the construction and maintenance of these sites.
As they are virtually in the ground and designed for certain types of waste, they must meet environmental and safety standards.
Let’s take a look at everything in detail.
The risks of not isolating them
Assuming that proper disposal is essential, many types of waste can take years, even decades, to disintegrate and complete natural decomposition processes. At this stage, they produce a large amount of slurry, such as leachate, which is extremely contaminating for the soil and for groundwater.
Moreover, biogases are also produced, mainly methane and carbon dioxide, due to the breakdown of organic material, which must be controlled and could be used to produce renewable energy.
How to isolate them
Controlled landfills need to be isolated from the ground that hosts them, but to be safe they need to fulfil different functions.
Surface erosion control
Vegetation naturally protects the ground from erosion by weather conditions such as wind and rain, which would cause subsidence. While waiting for grassing to protect the sides and surface of the landfill, anti-erosion geomats, in a biodegradable and synthetic version, can be chosen according to needs.
TeMa Geo Solutions offers a wide range to choose from, which can be browsed here.
Reinforcement
A landfill site is sometimes designed and built on more or less steep slopes. If a slope is steep and the ground is unable to support itself, retaining grids need to be installed in order to prevent slippage, which would expose and damage lower layers. View all our solutions.
Drainage
Specific products, drainage geocomposites, can be used for the drainage of rainwater and leachate, which inevitably builds up and must be kept away from the ground.
Barrier
Bentonite-based products, such as Barrier Bento, allow the area to be waterproofed, including walls with high slopes and the bottom.
Capping
Landfills also have a final cover that must meet precise criteria. These include isolating waste from the ground and surface erosion control. However, minimising water seepage and blending into the landscape are equally important.
New solutions in road construction and/or repairs
The safety of road infrastructures is the main goal, and maintenance work – whether preventive or supplementary – is systematic.
Road surfaces withstand heavy traffic loads and atmospheric changes with significant variations in temperature. Constant maintenance is therefore required in order to ensure even surfaces and the stability of structural elements.
Let’s look at the main factors involved in building new roads or maintaining roads.
Controlling surface erosion
Erosion is largely due to freeze/thaw cycles, which make asphalt less elastic and therefore more prone to internal voids. Such voids allow water to penetrate into underlying layers, gradually eroding the structure.
In addition, heavy traffic loads, especially heavy vehicles, cause deformation of the surface layers: this results in water penetration, which “softens” the structure and makes it less resistant.
Anti-capillary drainage
The water capillarity, i.e. the ability of liquids to move in micro-spaces even against the force of gravity, is a rather complex concept closely monitored in the construction industry. With the help of pressures exerted on lower layers, water rises upwards, dragging the finer components of materials with it and causing deformation.
It is therefore necessary to provide a drainage geocomposite, a three-dimensional membrane obtained by bonding two or more synthetic components in order to convey fluids to the exterior and prevent them from rising.
You can discover all our solutions here.
Reinforcement
It may sometimes be necessary to install reinforcement grids, especially if there is a more or less pronounced slope that would cause a road shoulder to slide downwards.
The choice of the most suitable type of reinforcement, and therefore also of the position of the geogrid in the layering, clearly depends on the problems to be faced i.e. reinforcing the surface area to limit the spread of cracks to underlying layers, improving the load-bearing capacity and reducing the stresses transmitted to lower layers, or providing a separation (and anti-contamination) function.
Discover all our solutions here.
Stabilisation
During intervention works, softer soils may be encountered, which may be subject to instability or even collapse in the early stages of intervention works. Even if this should not jeopardise the feasibility of the works, there is still the risk that the minimum legal safety requirements will be compromised.
Also in this case, geosynthetic products are the solution to the problem, as they absorb tensions at least until the intervention work achieves structural stability.
Discover the solutions in the X-Grid line here.
- Published in Drainage geocomposites and membranes, Erosion mats, GEO, Geogrids, Roads
Embankments in home gardens: small colourful islands
Made of masonry alone, embellished with different types and colours of plants and flowers, and of varying heights, embankments are often part of public buildings in parks and squares, but also a distinctive feature of private gardens. In the urban construction context, embankments can be borders for roadside verges, steps and flowerbeds, reaching a relatively low height, almost always less than 1 metre.
The provide a very attractive and organised visual effect and can be customised with the colours and types of plants you prefer. However, in order to achieve adequate stability for such intervention work, regulations require certain specifications to bear in mind for their construction.
A short and simple recap: let’s start by understanding what they are and how they are built.
What are embankments?
Embankments are accumulations of earth that form more or less evident differences in the level of the ground and can be natural or artificial. Natural embankments are caused and possibly accentuated by landslides, whereas artificial ones are man-made and consist of an earth fill supported by a wall, often in order to highlight the difference in level.
The risk of landslides
As mounds of earth, especially if they are of a certain height, embankments can be severely tested by atmospheric events, resulting in erosion and runoff due to rainwater.
Various characteristic elements can therefore be recognised:
- drainage and runoff systems in the underlying area where all rainwater accumulates;
- support and reinforcement of slopes, the part most susceptible to erosion;
- substrates and erosion control systems to allow plants to grow in the best conditions by sheltering the topsoil from the effects of the wind, sun and rain until the plants have become strong and well-rooted.
Block retaining walls and reinforcement grids
In order to prevent soil erosion or irrigation, embankments are reinforced with retaining walls in a combination of concrete blocks and geogrids, which meet geotechnical, building and architectural requirements.
TeMa Geo Solutions has the right products to create this type of construction.
For soil reinforcement we suggest X-Grid, reinforcement geogrids, which are knitted uniaxial geogrids made of high tenacity polyester yarns covered with a protective PVC layer.
For retaining walls, the range includes T-Block, a single concrete block for building reinforced walls.
The special feature of this product is the male/female joint, shaped directly on the block. This ensures maximum connection between the blocks, thus avoiding the use of mechanical fasteners, glue or mortar and making the wall stronger and more resistant to damage.
Find here all the specifications of the products mentioned.
Protecting the vineyard landscape: tried-and-tested technologies… sitting lightly in the field.
The photo conjures up a lofty tale: “Autumn arrives and with it, the first rains, days draw in, the temperature starts to drop and, above all… it’s harvest time!”
We’re in the eastern corner of the Veneto region, the Prosecco hills have outdone themselves once again this year and a steady stream of grape-laden trailers continue to roll past on their way to the wineries. But this year’s harvest has had to contend with rather uncertain weather patterns: frosts in late spring, persistent rain interspersed with dry spells, with violent storms and hail over summer.
These conditions certainly don’t help the soil, putting it at risk of slips, subsidence and erosion. But if we apply TeMa Geo Solutions’ modern technologies and materials designed for this very purpose, we can protect the land from damage and, what’s more, do it in a sustainable way.
Not far from here, just a few kilometres from our headquarters, the Prosecco hills fall largely within the UNESCO World Heritage Site, meaning any measures must be strictly reconstructive, designed to protect the status quo and absolutely non-invasive: “gentle” on the environment.
TeMa Geo Solutions has come up with high-performance solutions to control the natural erosion of the soil, reinforce slopes, and drain water with:
- biodegradable fibre matting made from 100% natural jute such as Ecovernet® J500 XL and Ecovermat P Grass, which provide protection to stop soil being blown or washed away by the elements, and encourage vegetation;
- the K-Mat F erosion control synthetic geomat;
- reinforcement geogrids such as X-Grid PET PVC, which can withstand considerable stress levels;
- the Speedrain drainage geocomposite, which drains away water from the surrounding soil, stabilizing any surface slips.
Products
If you wish to receive more information, CONTACT US or take a look and download our “Vineyards” catalogue.
Geosynthetics: Advantages and Applications
Our passion for work does not stop, it simply continues at our company, in a little more limited way. You certainly cannot see us running up and down building sites or going in and out of our research labs, but we can assure you that we are still working on our production of geosynthetic products with the same commitment and perseverance in order to formulate new projects and develop ideas that we will see materialised soon, once everything has ended.
TeMa and Geosynthetic Products
TeMa Geo is the TeMa division created almost thirty years ago with the aim of exploring and expanding the world of geosynthetics, which it still does today. By “geosynthetic products” we generally mean all categories of synthetic coverings that are not only used in contact with earth or other building materials but are also appreciated for their use in various building fields. In the building industry, their main advantage is that they are user-friendly in technical terms, which is why engineers and planners prefer them to other technical solutions.
The Advantages of Geosynthetics
The advantages of geosynthetic options not only lies in the fact that they are easy to use but also in their cost-effectiveness: certainly less expensive, they provide excellent performance that remains unchanged over time. Furthermore, their versatile use makes them the ideal solution to various on-site problems.
Geosynthetic Products “In the Field”: the Serravalle Project
In more practical terms, today we want to tell you about the intervention works we carried out in the Piedmont region in 2016. It involved extension works for Serravalle Retail Park. In preparation for the works, we had to make the slope in front of the new complex safe. In order to proceed, we had to prepare several reinforced soil structures, separating them into banks, and solve the problems of surface drainage for the management of water, whose catchment area was located above the area.
For works of such magnitude, we used geogrids from the XGrid PET-PVC range as a structural element. In addition, to avoid any seepage in the future, drainage elements were installed close to the reinforced structures of the horizontal sections of each berm. This is just one of our products and one of the many fields of application explored by TeMa.
To discover all our membranes, visit our section dedicated to products.
- Published in GEO, Geogrids, Reinforced earth structures, Reinforced earth structures - Drainage
Cycle/pedestrian paths: when we get back onto our saddle, we’ll know more about them…
We know that our bike has become a mirage. But we can promise ourselves to use it more when this period of seclusion is over. Meanwhile, why don’t we take advantage of the time available to discover interesting things all around us? For example, cycle paths. Let’s start at the beginning.
What is the correct definition of a cycle/pedestrian path?
It’s where you can ride your bike, of course. But, can pedestrians walk on it too? What is the direction of movement? Then there are increasingly more complex questions, such as: has it been built as a separate cycle path or as a reserved lane? Is it a cycle/pedestrian path or a vehicular/cycle path? In short, there are many features that a cycle/pedestrian path must have in order to be defined as such. Let’s take a look at them together.
The cycle/pedestrian path was invented to allow pedestrians and bikes to get about. Such paths require cyclists to respect pedestrians and get off their bike whenever necessary to avoid getting in the way. Consequently, they are not paths for the exclusive use of cyclists.
Creating these kinds of paths encourages people to get about without using a car, thanks to these dedicated spaces, where they can feel safe from urban traffic.
How do you build a cycle/pedestrian path?
In 2018 TeMa Geo Solutions built a cycle/pedestrian path in Cozzuolo di Vittorio Veneto (TV). One of the main aims of the project was to improve road safety in an area that is a gateway to the city and where a city park is situated, used by families and children.
First of all, we enlarged the road and the nearby roundabout in order to create the necessary space for inserting the path. The enlargement was facilitated by the construction of a reinforced earth escarpment, for which reinforced geogrids were used. Installed in the ground, they create friction and enable the system to withstand significant levels of stress. The intervention work, designed on the basis of a single berm positioned at about 2 metres above ground level, allowed pedestrian and cycle traffic in an area that had been dangerous from the outset.
Looking on the bright side, when you get back onto your saddle, you’ll be more aware of what’s under your wheels. Enter the TeMa world, visit our website.
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