Soil mixing Description

Transcription

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2 Description Soil mixing is a method of soil improvement through the addition of binding agents, which are added to the ground as cement suspension in wet form. The binding agent is injected through nozzles at the lower end of a hollow drilling linkage. When the mixing tool (a hollow drilling linkage with blades or paddles at the lower end) is drilled into the ground, the binding agent is added. In doing so a partial mixture with the soil is obtained. Once the final depth has been reached, the mixing tool is extracted and additional binding agents are injected. Due to the change in rotational direction and the alternating up and down movements, a homogeneously mixed soil column is produced. 2

3 Applications Applications of soil mixing: Cut-off walls Lining walls Structurally load-bearing support elements (installing steel beams in freshly mixed pile) Infilling elements between support piles or lining supports Column-shaped or block-shaped support elements Area-wide soil improvement Stabilisation columns Soil types Soil mixing is particularly well suited for non-cohesive mixed soils (gravel/sand mixtures). Soil mixtures of gravel and coarse silt are equally suitable. Stones present in the soil are not a problem provided they are no larger than fist size. In cohesive soil types it is not usually possible to completely mix the soil through with binding agent. Furthermore, only a low stability can be achieved in cohesive soils. Advantages Vibration-free Low noise level High productivity Variable arrangement of columns No aggregates required Environmentally friendly Applicable in contaminated soils (no excavated soil) 3

4 Production Positioning of mixing tool. Inserting the mixing tool under addition of binding agents. Mixing of the soil down to final depth. Rotary extraction of the mixing tool under addition of binding agents. Setting of the soil/ binding agent mixture. 4

5 Production The mixing tool (available as single, double or triple unit) is attached to the carrier machine. Multiple units offer the possibility of being mounted in lateral or longitudinal direction. Dimensions of the individual elements approx mm approx mm approx mm approx mm approx mm approx mm 450 mm 450 mm Dimensions Carrier machine LB 16 LB 20 LB 24 LB 28 LB 36 LRB 125 Max. effective length approx m approx m approx m approx m approx m approx m LRB 155 approx m* LRB 255 approx m* LRB 255 (with extension) approx m* * Depending on leader configuration 5

6 Equipment technology Technical data: Rotary drives Model Speed Max. torque Max. pull force Max. crowd force MA / 120 rpm 35 / 16.5 knm 300 kn 300 kn MA 35 Turbo 100 / 200 rpm 35 / 16.5 knm 300 kn 300 kn MA / 100 rpm 63 / 31.5 knm 300 kn 300 kn MA 60 VAR rpm 57.5 knm 450 kn 300 kn MA 60 VAR CHUCK rpm 57.5 knm 450 kn 300 kn All carrier machines of the Liebherr LB series (drilling rigs) and the Liebherr LRB series (piling & drilling rigs) can be used for producing soil mix columns. The MA 60 VAR is available with hollow chuck as an option. Thus, the length of the drilling linkage may exceed the leader length. There are two speed ranges for the mixing drives MA 35, MA 35 Turbo and MA 65. The variable drive of the MA 60 VAR can be continuously adjusted during operation. 6

7 Equipment technology Single unit Double unit, lateral Double unit, longitudinal Triple unit, longitudinal 7

8 MA 60 VAR and MA 60 VAR CHUCK Drilling position, flushing head flange mounted MA 60 VAR MA 60 VAR CHUCK (with hollow chuck) 8

9 Drilling position, flushing head leader guided Position to move carrier machine Drilling position, with extension Flushing head Leader Clamp Connecting bar 9

10 Special method Dry soil mixing Soil conditions can also be improved by adding the binding agent in dry form. The binding agent cement, lime or a mixture of both is added as powder and mixed with the soil. It is dry-injected into the soil and mixed with it by means of compressed air through nozzles which are located at the lower end of the hollow drilling linkage. The binding agent reacts with the soil moisture to form columns similar to the ones produced by soil mixing in wet form. 10

11 Notes 11

12 LWN /2010 Subject to change without notice. 12 BVV Spezialtiefbautechnik Vertriebs GmbH Bleibtreustrasse 9, D Munich/Germany Tel.: Fax: Liebherr-Werk Nenzing GmbH P.O. Box 10, A-6710 Nenzing/Austria Tel.: Fax: