Geotechnical Engineering

Geotechnical Engineering- Our Flagship
 

Geotechnical engineering applications were Ryobi G’s flagship services back in 2000. After years of continuous improvement and striving for higher quality in this ever changing society, Ryobi G has proven to be one of today’s leaders in geotechnical engineering works here in Singapore. This positioning in the industry is noticeable with the various projects that consists of both government tenders and private projects in Singapore. With the increasing demand for quality civil infrastructures in Singapore, Ryobi G’s reliable and trusted quality of geotechnical engineering services will continue to stay relevant and the Ryobi G geotechnical team is confident to play a significant role in building and improving our urban city.

Our geotechnical engineering techniques in Singapore include:

  • Micropiling

  • Grouting

  • Soil nailing

  • Retaining wall

  • Ground Anchor

  • Rock bolting

  • Geocells

  • Guniting

  • Shotcreting

  • Recharge well

  • Relief well

  • Slope repair and stabilization works

  • Design and build

  • ERSS

  • Geotechnical Consultation


Applications:

  • Soil improvement

  • Soil support

  • Slope Stabilization

  • Deep excavation

  • Basement construction

  • Road construction

  • Rock reinforcement

  • Earth retention

  • Repairing concrete work

  • Underpinning

Micropiles

 

Piles and micropiles are considered as one of the deep foundation techniques to enhance ground improvements. A micropile is most commonly known as a structural element that is placed beneath the ground to transfer load settlement. Installation of micropiles are be in isolation but more commonly in clusters/groups. 

As opposed to piling, diameter of micropiles usually range from 75mm to 300mm. Although the principle of both piling techniques work similarly, micropiles are constructed using C5-C6-C6XP in Ryobi G. These machines allows continuous drilling with bentonite, water or even cement grout. Ryobi G has the appropriate machines for different situations for micropiles.  For instance, we  counter space constraints with the availability of  small-sized machinery that are versatile and  able to maneuver in tightly enclosed areas.

 

History of micropiles works dated back to post World War II for damaged buildings.  Today, it is used widely to support older structure, increase load capacity of buildings. In fact, it is much more economical for contractors to strengthen the foundation than to tear  down existing building and construct a new one.

The advantages of micropiles are aplenty. Micropiles are generally smaller, lighter and more economic as compared to other deep foundation technique. From an environmental standpoint, installation of micropiles through the rigs is low emission with limited vibration and noise disturbance.  The general properties of micropile; with high load capacity and resistivity to compressive and lateral loads have also made this technique very popular in deep foundation construction. 

 

Micropiling also has a huge range of applications and they are not limited to the below: 
a) underpinning works
b) structural and foundation support
c) supporting new load and retrofitting
d) pile wall



 

From Top: The use of soldiers piles and tension piles as part of our micropile capability.There are many types of micropiles  to date. The most commonly known ones are; soldier piles, driven piles, soil nails and ground anchors.

Bottom: Micropile works with C6XP  along Upper East Coast Road.

Underpinning
 

Underpinning strengthens the foundation of an existing structure/structure. There are many factors that could attribute to the use of underpinning. For instance structural changes, weakened foundations foundation and even altering current foundation instead of building new ones.

From the above applications of underpinning, grouting is also seen as a good alternative to conventional piling  method. Instead of inserting high strength steel  beams, grouting is more cost effective. This  technique works based on the physical property  of the grout and it is independent of the ground  foundation.

For this underpinning work done in a shopping mall, we helped  our client saved over $1m then to strengthen existing structure than to build new ones.

Earth Retention Structure System
 

Earth retention structure system (ERSS) is a mean of providing structural support to construction site in the early phase of construction. There are a multitude of ERSS methods; soil nailing and ground anchor are known as the most commonly used ones. Despite their primary function that is to provide structural support, they are suited for different situations.

Soil Nailing

In Geotechnical Engineering, no single technique is restricted to only one aspect of ground improvement. Taking soil nailing as a prime example, it reinforces soils slopes,  excavation and well as retaining slopes via reinforcing bars. There are several  other techniques that offer different uses and applications, depending on the  nature of the situation.
 

Soil nailing is typically suited for  “soft” earth whereas ground anchor  is meant for ‘’hard’’ earth. They have  different mechanism to provide  structural support too. Soil nailing  generates tensile force in deformed  slope whereas ground anchor  employs heavy stress to minimize  deformation.

A combination of soil nailing works and guniting/shocreting done simultaneously. An alternative use of GFRP soil nailing has been popular in the recent years. We are proud of our capability to carry out soil nailing via the use of steel rebar and GFRP (Glass Fiber Reinforced Polymer)

The main advantages that soil nailing bring about to slope stabilisation techniques  it that this method is relatively inexpensive and the installation process is fast and straightforward. in the event of soil nail installation, the machines are usually small in size, which means the process of soil nail installation does not require huge amount of space to work about.  Soil nails could be used on heterogenous ground which means the ground could be a mixed of gravels and hard rock. In addition, the most important technical aspect of soil nails is that it limits the deformation in area of interest and when these soil nails are stressed, the load will be redistributed  to the other soil nails. 

 

General applications of soil nailing includes but not limited to the below:

a) slope repairs in urban and suburban area
b) reconstruction of retaining structures
c) Provision of long term stability to existing structure without destructive test

d) Retrofitting bridge abutment 
e) Stabilisation of natural/artificial steep slope. 
f) Soil nailing nearby 

From the Top: Soil nails are installed usually with C6 machines. Whether the soil nails are made of  steel beams or GFRP, guniting is conventionally carried after in installation of BRC and soil nails installation. 

To date we have used the 2 different types of soil nails and the thickness of gunite are usually from 150mm to 220mm. 

From the Top: Ground anchors are installed usually with C6/C6XP machines. Whether the soil nails are made of  steel beams or GFRP, guniting is conventionally carried after in installation of BRC and ground anchor installation. 
 

Ground Anchors
 

Soil nailing is typically suited for  “soft” earth whereas ground anchor  is meant for ‘‘hard’’ earth. They have  different mechanism to provide  structural support too. Soil nailing  generates tensile force in deformed  slope whereas ground anchor  employs heavy stress to minimize  deformation. Ryobi-G also boast of being the first contractor in Singapore/Asia to employ the use of of GFRP ground anchor.

Light and versatile, GFRP ground anchors are easier to handle as compared to conventional rebars. This ground anchor technique is employed in the construction of DTL3. Whether these ground anchors are steel ones or GFRP,  these anchors come in a wide range of length and capacity which are suited for different use; building support, structure support whether they are permanent or temporary ones.

Permanent ground anchors (steel) are more economical then GFRP ones, however they must rust overtime due to climatic changes. New versions of Steel ground anchors have additional corrosion resistant protection. GFRP ground anchors are not affected by climatic changes are can dual its role as a permanent or temporary support structures. GFRP ground anchors usually more versatile and preferred (as required by site requirements.)


A temporary ground anchor if it acts as a support structure as below 20 months and a permanent ground anchor usually acts as a supporting structure that takes more than 20-24 months. The choice of temporary/permanent ground anchors is largely dependent on sit requirement. 

Advantages of  ground anchors are aplenty.  This technique is economical. Ground anchors are able to withstand high load despite heterogeneous ground conditions, which also create minimal impact on the site/construction. Similar to soil nails, this method of ground improvement does not require huge amount of working space and ground anchors could be installed easily by the mobility of the machines. 

Most importantly, ground anchors has little environmental impact, which has become the local authorities' concerns of late. 
 

General applications of ground anchor includes but not limited to the below:

a) Slope stabilisation/protection
b) Slope construction near highway

c) Bridge abutment 
d) Foundations
e) Sheet piling

 

Guniting/Shotcreting
 

Slopes/Structures that have been stabilized through the use of soil nails, ground anchors or other ERSS are usually placed with BRC wire mesh followed by a final layer of gunite. In the construction phase, guniting is also used for slope stabilisation, retaining wall and even used in tunnel construction/rehabilitation work. 

Guniting, also commonly known as shotcreting is a process where a fresh mix of gunite is sprayed onto them. The gunite takes the  form of the structure despite the irregularities on the surface. Essentially, the guniting process enhances the strength of the structure, thus increases the surface  retention and provides surface protection. The end product of  guniting is to let the structure obtain high strength and low permeability. 

The versatility of guniting has brought about many advantages in the construction phase.The mix of guniting  can be prepared quickly and this saves time in the construction work. As compared to conrete,  guniting is relatively more economical and less labour intensive. The process guniting is relatively fast; the handler sprays the guniting mix through a nozzle over the BRC wiremesh (after installation of ground anchor/soil nails) repeatedly until the gunite form a layer of at least 150mm to 200mm. 

One of the major advantage is over concrete is that guniting can takes the shape of curved and folded sections, irregardless of the surfaces. (horizontal/vertical). 

Besides being able to take the shape of the structure,  the wetness and dryness of the guniting could be adjusted according by the engineer on site. 

Applications of guniting:

a) slope stabilisation

b) tunnelling

c) retaining walls

d) general structural reinforcement

3) restoration works

 



 

Guniting: Ryobi G has successfully completed guniting at 20m height.

Guniting: Our workers spraying gunite for repair works

Geocells/Erosion Control

Cellular Confinement Systems (CCS) are also known geocells are used mainly for  soil stabilization and controlling erosion. Similar to guniting, geocells are used for  structural reinforcement for support and retention. It usually employs the use of  honeycomb-shaped high density polyethylene (HDPE) on slopes which are steep  and with irregular topography. Not only does geocells provide functional use of  ERSS, it is able to give an aesthetical boost to the environment when these cells  are vegetated. The maturation of vegetation will further enhance the stability of the  slope through interlocking of plant roots.

Geocells: One of our local project employing the use of geocells which can help in erosion controls.

Relief well used in DTL3 -Extension

Recharge Well

When water seeps into an acquifer, it is know as ''recharge'' and hence the name recharge well suggests that ground water that seeps through and acquifer in an excavation site is know as recharge well. 

Usually, recharge well are used in deep excavation to return water back to the aquifer away from  the site dewatering system. It is typically use for controlling settlement of compressible  soils due to the change in pore water change, causing adverse effect to structures on top  of the soil layer. This eventually causes settlement at the excavation site that will damage nearby structures. Recharge well and relief well are usually carried out (not in sequence) at the projects we have carried out in Singapore. 

The 2 most commonly known techniques of recharge well are known as:

a) "Injection well" when water is pumped in directly to the ground itself for "recharge". This is a deliberate method of doing recharge well. 

 

b) using "gravitational force' for water to flow under gravity and seep into the aquifer.  

The selection of either techniques for recharge well largely depends on the site condition and projection requirements. 

 

 




 

Recharge & Relief Well
 

Relief Well

This technique has been used over the last century with the primary use of  tapping underground fossil fuels. Over the years, relief well have been employed in the field of oil and gas industry as well as geotechnical engineering industry. Ground water control is an important measure to control erosion and keep groundwater  from entering excavation. Relief well are used to reduce excessive pore water pressures  in stratified ground condition. This temporary control is typically drilled before excavation  goes beyond the piezometric level in the aquifer. When excavation continues, water will  overflow from the well by disposed passively or through pumping. 

The advantages of relief wells are that they generally easy to install and cost effective 


The nature of relief well can also be temporary or permanent depending on the needs of the nature of excavation work.

Relief well also have a huge range of applications as shown:
a) to relieve ground pressure and stabilizes ground condition

b) use on excavation in marine clay, jurong formation and fractured rocks

c) pit mining

d) geotechnical engineering

e) oil and gas industry

f) heaving, sand boils

e) flooding

Recharge well used in DTL3 -Extension

Geotechnical Design and Analysis
 

Ryobi G offers comprehensive build and design services for all of our geotechnical services  offered. We have vast pool of qualified engineers who are IT-savvy, using programs which  allow 3D visualization of any structural conflicts. After meticulous planning with our  prospective clients, this allows smooth transition from the designing phase to building phase  which can collectively save our clients’ time and effort.

 

Our Machines:
Casagrande 
-Used for projects involving soil nailing, micropiling, ground anchor, underpinning, recharge and relief well in Singapore.

Casagrande C6XP
-An improvised version of C6, this machine can be used for soil nailing, micropiling, ground anchor, underpinning, recharge and relief well.

Bunker-Teksped
-Used for projects guniting/guniting  involving in Singapore. 
Hanjin
-Used for projects involving Micropiling, recharge and relief well in Singapore.

Soilmec
-Used for projects involving micropiling in Singapore

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