Double rotary drilling

Transcription

1 Double rotary drilling

2 The ideal drilling machine for double rotary drilling 1 basic machine 1 drive 3 drilling methods Flushing head Sliding cylinder for relative adjustment Gear I Gear II Sheave head Rope crowd system (RDS) Auxiliary winch Lateral inclination device Leader Leader support arm Longitudinal inclination device Vertical travel device Support arm brace Leader swing device Radius adjustment device Basic machine The economical and compact solution for special deep foundation Economical use of the basic machine due to a high degree of utilisation Quick exchange of equipment when changing to another drilling method Compact design For this drilling method the total length of the drilling tool is mounted beneath the rotary drive and it is drilled to the projected depth in one step. The drilling depth depends on the available rig length.

3 Double rotary drive Process description The double rotary drive is used for various installation methods including cased and uncased drillings. The gear boxes which are mounted on a slide plate can be operated independently or contra-rotating. On the Liebherr basic machines the rotary drive is operated continuously up and down and with high pull and push forces. max Weight approx kg Technical Data (Based on Q = 300 l/min, p = 30 bar) Gear I (Casing) Engine type Number of engines Level 1 Level 1 min danm 4 min danm min danm 18 min danm 3 8 min danm 16 min danm Gear II (Auger) Engine type Number of engines Level 1 Level 1 15 min danm 30 min danm min danm 6 min danm min danm 30 min danm

4 Types of double rotary drilling Double rotary drilling Secant drilling with casing and continuous flight auger Displacement auger drilling Continuous flight auger drilling This drilling method uses a casing and a continuous flight auger which are driven by two independent rotary drives. The drill strings are contra-rotating. Due to the small dimensions of the rotary drives piles can even be installed close to existing walls. Casing and auger are drilled into the soil as one piece down to the final depth. During the drilling process the withdrawn soil is brought up to the surface by the auger in the space between casing and internal flushing pipe. After reaching the final drilling depth concrete is pumped to the bottom of the drilled shaft through the internal flushing pipe of the auger. At the same time casing and auger are extracted simultaneously. Finally the reinforcement cage is introduced into the liquid concrete. Drilling in front of the wall Secant bored pile walls Tangent bored pile walls Sealing piles In non-cohesive soils up to maximum density and in silt and clay up to stiff consistency. Piles can be installed directly next to existing buildings Casing and auger are contra-rotating, thus: Extremely precise drilling is ensured The soil is brought up easily and efficiently in the space between casing and auger A fast drilling progress is achieved Little noise and vibration are caused This pile is a partial displacement pile with a continuous flight auger on a large central diameter pipe. For installing the pile the drilling tool is drilled into the soil. Since the drilling tool is sealed by a watertight lost cap at its bottom, the soil is partly withdrawn and partly displaced to the side during the drilling process. After reaching the projected depth the reinforcement cage is introduced and the concrete is pumped in with excess pressure. The drilling tool is rotating when extracted (as it is when drilled into the soil). The cap at the bottom remains in the ground. Foundation piles Tangent bored pile walls All non-cohesive soils up to medium density, in silt up to semi-dense consistency. Little noise and low impact on the environment No vibration High bearing capacity A continuous flight auger with internal flush pipe is drilled into the ground as one piece down to the final depth. The flight fills up and brings up the soil that has not been displaced. This method of drilling requires no casing. Nevertheless it offers the same supporting effect as cased drilling since the auger is constantly filled with withdrawn soil. The total length of the drilling tool is mounted beneath the rotary drive. The continuous flight auger is drilled down to the projected depth in one step. After reaching the final depth concrete is pumped down through the flush pipe. The concrete escapes through a concreting hole at the bottom of the drilled shaft. The escaping concrete is under excess pressure and ensures that the emptied space is immediately filled with concrete during the extraction of the continuous flight auger. Foundation piles Pile walls Drillings for steel piles Sealing piles In dense up to loose soil and weathered rock. Not in homogeneous non-cohesive soil with a cohesive strength Cu < 15 kn/m. Little withdrawal of soil No casing Fast drilling progress Drilling and concreting with one system Very little noise and vibration

5 Examples of application Double rotary drilling Positioning of drill string Drilling of drill string Extracting of drill string Concreting of pile Emptying of auger nd. Ed 04/07 kom DESIGN 1 GmbH Munich #71008 BVV Spezialtiefbautechnik Vertriebs GmbH Bleibtreustrasse 9, D Munich/Germany Tel.: (+49) Fax: (+49) info@bvv-spezialtiefbau.de Liebherr-Werk Nenzing GmbH P.O. Box 10, A-6710 Nenzing/Austria Tel.: Fax: crawler.crane@liebherr.com