HORIZONTAL DIRECTIONAL DRILLING
Or HDD, is a steerable trenchless method of installing underground pipes, conduits and cables in a shallow arc along a prescribed bore path by using a surface-launched drilling rig, with minimal impact on the surrounding area. Directional boring is used when trenching or excavating is not practical. It is suitable for a variety of soil conditions and jobs including road, landscape and river crossings. Installation lengths up to 2000 m have been completed, and diameters up to 1200 mm have been installed in shorter runs. Pipes can be made of materials such as PVC, polyethylene, polypropylene, Ductile iron, and steel if the pipes can be pulled through the drilled hole. Directional boring is not practical if there are voids in the rock or incomplete layers of rock. The best material is solid rock or sedimentary material. Soils with cobble stone are not recommended. There are different types of heads used in the pilot-hole process, and they depend on the geological material.
TDS
MSDS
TUNNELLING
A tunnel boring machine (TBM), is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. It may also be used for microtunneling. They can bore through anything from hard rock to sand. Tunnel diameters can range from a metre (done with micro-TBMs) to 19.25 metres to date. Tunnel boring machines are used as an alternative to drilling and blasting (D&B;) methods in rock and conventional “hand mining” in soil. TBMs have the advantages of limiting the disturbance to the surrounding ground and producing a smooth tunnel wall. This significantly reduces the cost of lining the tunnel, and makes them suitable to use in heavily urbanized areas.As modern tunnels become longer, the cost of tunnel boring machines versus drill and blast is actually less. This is because tunneling with TBMs is much more efficient and results in shortened completion times.
• SC RETARDER • SC FOAM • SC GSTP • BENTOCRYL 86
Slurry shields are TBM fitted with a full face cutterhead which provides face support by pressurizing boring fluid inside the cutterhead chamber. These machines are most suited for tunnels through unstable material subjected to high groundwater pressure or water inflow that must be stopped by supporting the face with a boring fluid subjected to pressure. The cutterhead acts as the means of excavation, whereas face support is provided by slurry counterpressure, namely a suspension of bentonite or a clay and water mix (slurry). This suspension is pumped into the excavation chamber where it reaches the face and penetrates into the ground forming the filter cake, or the impermeable bulkhead (fine ground) or impregnated zone (coarse ground) which guarantees the transfer of counterpressure to the excavation face. Excavated debris by the tools on the rotating cutterheads consists partly of natural soil and partly of the bentonite or clay and water mixture (slurry). This mixture is pumped (hydraulic mucking) from the excavation chamber to a separation plant located on the surface which enables the bentonite-clay slurry to be recycled.
• Bentonil CF • Bentonil GTC4 • Bentonil Q • SC GSTP • SC MUD • SC PAC R • SC VIS LV • SC XGUM • SC RETARDER • SC FOAM • SC VIS HV
SPECIAL FOUNDATIONS
Bored Piles
Sometime referred to as drilled piers, bored piles are cast-in-place piles ranging from 600mm to 6000mm in diameter with a depth that can reach down to 100 meters. Bored piles are installed by first removing the soil by a drilling process and then constructing the pile by placing concrete in the hole. The simplest form of construction consists of drilling an unlined or unprotected hole and filling it with concrete. Complications that may arise such as difficult ground conditions and the presence of groundwater have led to the development of special drilling technologies. The choice of the correct drilling technology must be done in a way as to minimize disturbance of the surrounding soil. For cohesionless soils (sands, gravels, silts), whether under the water table or not, the pile borehole must be supported using steel casing or stabilizing muds such as bentonite suspension.
Diaphragm Walls
A diaphragm wall may be described as an artificial membrane made of reinforced concrete constructed in the ground by means of a process of trenching with the aid of fluid support. The most popular use of a diaphragm wall is for the construction of multilevel basements. The Origin of the diaphragm wall can be traced to the post-war years in Italy (early 1950’s) where adjacent reinforced concrete piles (known as secant piles) were used to construct a barrage or a cut-off wall for hydroelectric dams. To answer the need for increased water-tightness which could be provided by minimizing the number of vertical joints and due to the fact that the secant pile technique involved the partial destruction of a completed pile by the boring of an overlapping pile (a seemingly wasteful technique)a more elegant solution of excavating a trench in sections in which to cast a series of in- situ adjacent reinforced concrete panels was developed. The application of the diaphragm wall technique was gradually extended to solve problems involving the building of underground tunnels for rapid transit systems along busy streets, construction of deep basements without endangering the stability of the foundations of the nearby buildings, and the construction of closed-type docks and wharves.
• Bentonil CF • Bentonil Q • Bentonil GTC4 • SC GSTP • SC MUD • SC PAC R • SC PLUG • SC VIS LV • SC VIS HV
MINING EXPLORATION
Many surface and subsurface exploratory projects are undertaken with the aim of locating:
a) oil and gas accumulations and coal beds
b) concentrations of commercially important metallic minerals (ores of iron, copper, and uranium)
c) deposits of nom-metallic minerals (building materials – sand, gravel, etc.)
d) recoverable groundwater
e) various rock types at different depths for engineering planning
f) geothermal reserves; and
g) archaeological features.
Diamond core drilling: this method involves a pipe encrusted in industrial diamonds being used to drill through rock layers, with a “core” of rock being left in the centre of the pipe. This core is recovered and gives information not only about the rock types, but also about the relationships between the rock layers in detail.
Mud-rotary drilling: this method is used for drilling through soft rocks, sand and clay layers especially in the search for coal, oil or gas. A special mix of clay and water is forced down the drill hole turning a rotary bit, with rock chips returning in the “mud” slurry. This method is used for holes up to 3km deep and can be done from ships or offshore platforms especially in the search for oil and/or gas. A person who collects the chips and identifies the rock type and other information is known as a “mud-logger”.
• Bentonil CF • SC MUD L • SC MUD P • SC LUB • SC FOAM • SC PAC R
WATER WELL DRILLING
A water well is an excavation or structure created in the ground by digging, driving, boring, or drilling to access groundwater in underground aquifers. The well water is drawn by a pump, or using containers, such as buckets, that are raised mechanically or by hand. Wells can vary greatly in depth, water volume, and water quality. Well water typically contains more minerals in solution than surface water and may require treatment to soften the water. Most modern wells are drilled, which requires a fairly complicated and expensive drill rig. Drill rigs are often mounted on big trucks. They use rotary drill bits that chew away at the rock, percussion bits that smash the rock, or, if the ground is soft,large auger bits. Drilled wells can be drilled more than 1,000 feet deep. Often a pump is placed in the well at some depth to push the water up to the surface.
• Bentonil CF • SC MUD L • SC MUD P • SC GSTP • SC FOAM • SC PAC R • SC LUB • SC VIS LV • SC VIS HV
MICRO TUNNELLING
• Bentonil CF • Bentonil GTC4 • Bentonil Q • Bentocryl 86 • SC GSTP • SC MUD • SC PAC R • SC VIS LV • SC XGUM • SC RETARDER • SC FOAM • SC VIS HV
OIL & GAS
Hydrocarbon exploration (or oil and gas exploration) is the search by petroleum geologists and geophysicists for hydrocarbon deposits beneath the Earth’s surface, such as oil and natural gas. Oil and gas exploration are grouped under the science of petroleum geology. Drilling stops at regular intervals so that purpose-built steel pipes – or casing – can be installed, often in two layers. The gap between the casing and borehole wall is filled with cement. The casing and the cement form a non-porous barrier that prevents cross-contamination between the petroleum-bearing rock formation and any overlying aquifers. The casing and cement are pressure-tested to ensure that they can tolerate higher pressures than those expected over the life of the well. A wellhead – which contains barriers, valves, seals and a gas/water separator – is placed on the surface to maintain control of the well and the drilling rig is moved from the site. In onshore drilling, an area is fenced off around the well, which is now ready for production. The size of this area varies. In coal seam gas operations it is usually about 23m by 23m.