Contact Details:

Dr. Mikhail Ryzhevskiy - General Manager
Tel: +971 4 2713 006
Fax: +971 4 2713487
E-mail: ryzhevski@etazenath.com

OUR CONTRACTING SERVICES

1. Construction of tunnels, shafts and underground structures
2. Construction of shoring systems
3. Slope Stabilization
4. Foundations Underpinning and Structural Repair
5. Waterproofing of underground and above ground structures

CONSTRUCTION OF TUNNELS, SHAFTS & UNDERGROUND STRUCTURES

With the growth of the world population and the worldwide urbanization process, the urban future increasingly depends on the developing of the underground space potential.

We offer our technological expertise, technical capability, innovative design approach, tunnelling & civil construction experience of our lead engineers in the development of underground space use:

Transportation and communication

1 Underground parking
2 Communication lines & service tunnels
3 Highway and subway tunnels
4 Pedestrian passage ways

Environmental tunnels

1 Derivation tunnels & irrigation systems
2 Sewage and depositories
3 Water reservoirs and tanks
4 Water supply & water treatment facilities

Municipal, Energy and Defense facilities

1 Underground plants
2 Shops and storages
3 Oil, Gas and Radioactive waste storage
4 Civil shelters and Defense enterprises
5 Launching shafts and Research centers

Our core competencies in underground construction:

Soil/Structure Analysis by FEM
Analysis of every subsequent construction phase

Jet -Grouting Technlogy is one of the most safest, economical and time efficient methods for construction of SHORING SYSTEMS for various purposes:

1 Shoring for deep excavations
2 Retaining walls
3 Diaphragm panels for soil erosion control
4 Water Cut –Off walls
5 Costal Erosion Control Barriers
6 Quays Walls

SLOPE STABILIZATION

1. Slope stabilization provides support and reduces dangers associated with loose earth slopes and loose or small rocks on eroded slopes.

2. On the basis of experience and solid engineering background our specialists will offer the most appropriate and cost effective method for your slope project.

3. We employ the following technologies:
    Jet –Grouting, Minipiles, Shotcrete, Soil Nailing

4. Our in-house geotechnical design team performs detailed Soil Stabilization analysis using FINITE ELEMENT Method.

OUR CONSTRUCTION METHODS

1. 3D Finite Element Analysis
2. New Austrian Tunnelling Method (NATM ) or Sequential Tunnel Excavation
3. Top - and - down construction
4. Jet -Grouting
5. Shotcrete
6. Soil Nailing & Anchoring
7. Minipiles
8. Chemical Injection
9. Horizontal Directional Drilling Method Statement

3D FINITE ELEMENT ANALYSIS METHOD

1. For every project of any scale that we undertake, our in-house design team will execute:
3D Simulation Model
2. Dynamic analysis of structure (vibration, impact, wind force, earthquake)
3. FE Analysis with consideration of Soil/Structure Interaction
4. Soil/Structure Analysis for construction of Jet -Grouting Shoring wall and its impact on nearby building.
Abu – Dhabi, 2009

NEW AUSTRIAN TUNNELLING METHOD (NATM)

NATM Concept
Tunnel is excavated by parts: headings and rounds. Excavated parts (drifts) are immediately supported by the initial or primary layer such as sprayed on concrete, and followed by the application of a secondary layer, which may consist of the reinforced concrete.

NATM engages physical properties of excavated earth itself (deformations, stress & exertions) and incorporates them in the whole process, whereas surrounding earth and tunnel layers work together as one load-carrying system.

NATM Advantages:
Flexibility to adopt different excavation geometries and very large cross sections;

Suitable for various ground conditions, including very weak and unstable soils ;

Allows construction in busy urban areas without disrupting surrounding traffic;

NATM enhances the self-supporting capacity of the rock or soil by mobilizing the strength of the surrounding ground;

Flexible adaptation to different ground conditions: excavation and support can be varied to suit conditions as they are actually encountered.

NATM BASIC STEPS

Finite Element Analysis (FEA)

Numerical methods of analysis (FEA) are used to model each sequence of excavation and behavior of tunnel linings in terms of the stresses and deformations. Our team of experienced professionals performs a number of complex structural 3D simulations, to identify all possible scenarios and risks associated with the tunnel excavation. Much advanced FEA is performed on sophisticated LIRA program, which is being continually developed and perfected for the past 15 years. Analyses are done in elastic and plastic modes

Tunnel excavation

Excavation face is usually divided into small drifts that will help the ground stand until completion of the support lining. The tunnel section is developed in staged series of small advances in a defined and controlled pattern and work sequence.

Initial and final lining

Initial lining (sprayed on concrete) provides support by accommodating all ground loads during sequential excavation. Initial lining is executed by SHOTCRETE, the most used concrete application technique for this purpose, within minutes after rock/soil is excavated. During design stage we perform FEA of initial lining on its structural capacity; the results dictate what thickness of concrete layer is required and whether reinforcement (lattice girders, wire mesh & etc) is needed for optimum efficiency.

Final lining is according to contract criteria and usually consists of additional shotcrete or cast-in-place concrete, often with a waterproofing membrane between the initial ground support and the final lining.

Monitoring

Extensive monitoring of ground mass properties during construction is performed to verify and/or adjust design accordingly.

Top-and-down is a construction method, which builds the permanent structure elements of the basement along with the excavation from the top (ground level) & to the bottom, and from the ground level up simultaneously.

Top-and- down method is mainly used for two types of urban structures: tall buildings with deep basements and underground structures such as car parks, underpasses and subway stations.

For tall buildings with deep basements, a full application of top-and-down method enables superstructure to be build concurrently with excavation and construction of the basement, giving a significant advantage in reducing the overall construction time.

ADVANTAGES

1 Minimizes the duration and disruption to surface traffic and other urban activities;

2 Allows early commencement of superstructure construction without the need to wait for excavation reaching the bottom level;

3 Time efficient and cost effective, does not require temporary bracing system;

4 Minimizes soil movement induced by excavation works which is an important factor for some sensitive locations.

JET –GROUTING

JET –GROUTING APPLICATIONS

Jet –Grouting is a universal and economical construction technology, that can be successfully applied for:

- Construction of Shoring and Earth Retaining Systems
- Shaft excavation, including access shafts for TBM
- Construction of a “Canopy” for tunneling
- Cutoff wall for seepage and erosion prevention
- Ground improvement or ground modification
- Elimination of water flow into open excavation

Minimize subsidence
- Settlement of above and under- ground structures (tracks in a tunnel for example),
- Underpinning of basement constructions

JET –GROUTING DEFINITION

Jet Grouting: An in-situ injection technique employed with specialized equipment that includes grout pump(s), grout mixer, drill rig, drill rods and injection monitor with horizontal radial nozzles delivering high velocity fluids to erode, mix, and stabilize in-situ soils using engineered grout slurry

In our Jet -Grouting projects we use ultra high-pressure fluids or binders that are injected into the soil at high velocities.

These binders (water-cement mixtures) break up the soil structure completely and mix the soil particles in-situ to create a homogeneous mass (Soilcrete), which in turn solidifies.

This ground modification / ground improvement plays an important role in the fields of foundation stability.

ADVANTAGES

1 Nearly all soil types can be Jet –Grouted;
2 Treatment to specific subsurface locations;
3 Safest method of construction;
4 Much faster than alternative methods;
5 Does not lead to a degradation of the subsoil;
6 No vibrations are induced into the soil during application;
7 Jet grouting columns may be configured in a variety of shapes as required.

SHOTCRETE

Shotcrete is construction technique where Concrete is projected or "shot" under pressure using a feeder or "gun" onto a surface to form structural shapes including walls, floors, and roofs.

Shotcrete has high strength, durability, low permeability, excellent bond and limitless shape possibilities.

These properties allow shotcrete to be used in most cases as a structural material.

Although the hardened properties of shotcrete are similar to conventional cast-in-place concrete, the nature of the placement process provides additional benefits, such as excellent bond with most substrates and instant or rapid capabilities, particularly on complex forms or shapes.

In addition to building homes, shotcrete can also be used to build pools and artificial rock.

Advantages

High compressive and tensile strength of finished works; Low Permeability; Excellent bond with most substrates and limitless shape possibilities; Flexible, rapid and cost effective solution; High production rate.

CONSTRUCTION OF SWIMMING POOL BY SHOTCRETE

In many construction cases Minipiles can be economical and more appropriate alternative to the conventional piling.

Minipiles generally have a diameter of between 100 mm and 250 mm and are reinforced with steel bars.

Installation can be performed to about 60 m depth or more, even though vertically control will become more difficult at greater depths

APPLICATIONS

For light industrial or domestic buildings to reduce differential settlement between old and new construction; To strengthen the structure; As settlement reducers; For Reinforced soil; For Slopes stabilization; Below buoyant structures; Below towers and masts

Minipiles can deal with many problems of headroom limitation, such as underpinning work. In general, they can overcome large or numerous obstructions in the ground.

The installation can be driving small-diameter steel tubes followed by injection of grout with or without withdrawn the tubes.

Where Minipiles are employed, combined resistance of pile cap & piles may be used to take horizontal loading.

CHEMICAL INJECTION

Chemical Injection is a general term applied to injection processes, which use special chemical solutions to repair cracks in the structures above and below ground.

Chemical injection is also effective in stopping water penetration through cracks in concrete walls and slabs.

Basically Chemical Injection addresses the structural concerns by acting as a glue-like substance in the crack. There are many types of chemicals that have been developed for these uses. Most employ an activator to expand the gel once in the crack on the concrete surface.

Expansion of 300 per cent by volume is possible with current technology.

ADVANTAGES

Restores structural and/or design strength to the cracked concrete structure;
Prevents corrosion of reinforcing steel and pre-stress tendons by encapsulating them against moistures; Stops the leakage of air, water and fluids through cracks in concrete structures;
Inexpensive when compared with the remove and replace option for affected structures.

OUR EQUIPMENTS

1. Drilling Rigs
2. Injection Plants
3. Drilling Attachments
4. High Pressure Pumps
5. Mixer Plant
6. Cement Silos
7. Shotcrete Equipment
8. Sheet Piler
9. Excavators and Skids
10. Power Generating Equipment