DE19740800A1 - Plank introduction device into ground using pile-driver - Google Patents

Abstract

The device has a bentonite suspension which is pressed into the earth area with the aid of at least one flushing lance (5) fixed to planks (3a,b) in their lower area. A vibration driver (4) is operated with a constant frequency of 30 to 50 Hz and a permanent advance feed force control. The bentonite suspension after vibration is fixed and forms a compressed structural base (1)

Description

The invention relates to a method for introducing Planks, especially sheet piles or duct boards in Soil with the help of vibrating bears.

The installation of planks, especially sheet piles or channel planks in the ground, is used for the temporary or lost shoring used to e.g. B. built trenches or manufacture pit enclosures. The use of these planks as a constructive element Buildings such as B. with foundations and walls also possible.

Process these planks through vibrating bears in soil bring in, z. B. from BMT 2, April 1995 (Construction process engineering) known. Come here Vibrating bears are used, their working frequency with 30 up to 50 Hz far above the natural frequencies of normal Soil is located and therefore a low vibration Enable work.

Especially for floors with a high storage density To simplify placing the planks in the ground, are used to support ramming in used essentially two ramming aids.  

On the one hand, this involves flushing with Water and the other about the arrangement of Relief drilling. Both methods are e.g. B. from the TIEFBAU 3/1995 magazine known.

In the known flushing method, the sheet pile is used Dishwashing lances attached through the water at the bottom the plank is pressed into the ground. The flush pressure depends on the nature of the soil. By this suspension of the soil will end up on the planks has loosened the ground, which enables the planks with less work to collect.

In the drilling method, relief bores are used Diameters depend on the nature of the soil, in the sheet pile route brought down to the encountered Reduce storage density.

When it comes to flushing water, it has proven to be disadvantageous proved that the soil loosening does not reappear can be subsequently compressed so that it is Settling the ground, for example, can lead to subsidence can, which can cause damage to buildings in particular.

Another disadvantage is that it is in operation High frequency vibration bears to an emission of kinetic energy comes, which damages the leads neighboring building fabric. Also one increased sound radiation observed. All the more so because the planks like big when standing up sound-generating membranes work.  

When using high-frequency operated Vibration bears have been shown to increase Penetration depth of the planks and the associated planks higher power consumption the speed under the High frequency range can fall, so this in turn an undesirable vibration propagation in the area of Natural frequencies of the building surface and the The specified minimum values of the Vibration speed leads.

The object of the invention is a method of the beginning to improve the type mentioned so that loosening of the building ground only during the Loading activity of the planks is generated and the sound and vibration emission when using in particular high-frequency vibrating bears beyond the known measure is also reduced.

This object is achieved in that while using a thixotropic Bentonite suspension as a lubricant and detergent and one low-frequency to high-frequency vibrating bear the planks are driven into the ground.

Because of the thixotropic properties, the Bentonite suspension only under mechanical Stress such as z. B. when vibrating the planks occurs, fluid and thereby, compared to Water, much better lubrication properties. This ensures that the planks with a less work is put into the soil and the vibration velocity coefficient is reduced.  

In addition, the lubrication with the Bentonite suspension a significant reduction in Radiation of kinetic energy, causing damage to the surrounding buildings are avoided. The This also reduces noise emissions.

Furthermore, the thixotropy of bentonite Suspension that this is at rest again solidified and so after the planks were brought in, or even after pulling the planks with it Process an optimal and resilient building surface is present.

It is advantageous if the bentonite suspension is used Help at least one attached to the planks Flush lance in the lower part of the planks in the ground is pressed, since in this case the suspension is not only loosens the floor in the foot area of the planks, but also from there to the surface of the building ground flows and so does the skin friction between the Screed and the soil.

For this it is particularly advantageous if the thixotropic bentonite suspension compressible and is processed in particular without lump formation, so that the flushing lances for the bentonite lubrication by means of a Pump unit can be permanently applied to the suspension with up to 250 bar pressure, d. H. especially with high pressure with low flow or but with low pressure and high flow during the Press vibration process into the ground.

It has also proven to be advantageous if before the installation of the planks of the building ground with holes  is provided, the diameter of which varies according to the Soil quality. The position of the holes results from the type of used Sheet pile profiles, so that especially in the area of Locks of two planks make displacement easier is achieved.

An advantage of this process is that the Control of the feed force on the vibrating bear is connected downstream, which ensures that the Vibrate the planks throughout Operating time and regardless of the penetration depth of the Screeds with a constant frequency of 40 in particular Hz takes place. This ensures that the Vibration bear always at a sufficient distance from the Natural frequency range of the floor and the neighboring ones Development of about 18 Hz works.

With the method presented here can advantageously also during the vibration of the Screeds continuously at several measuring points computer-controlled the emission of the vibrations several parameters checked and evaluated graphically become. This ensures that the specified Limits of vibration speed and noise emission not be exceeded.

In the process according to the invention it was found that the Vibration and noise emissions compared to conventional ones Process by a factor of at least 2 to fall below 10.

An embodiment of the method according to the invention is shown schematically in the accompanying drawing and is described in more detail below.

At the location of the subsoil with the surface 1 , where a sheet pile wall is to be placed, vertical bores with a diameter of 150 to 400 mm, in particular of 250 mm, are first made with a auger 2 at the locations, where the later sheet pile wall connection locks the individual sheet pile wall elements 3a are.

A flushing lance 5 is centrally attached to the sheet pile element 3 a, which is fastened with its nozzle opening 6 at the lower end of the wall element 3 a. The flushing lance 5 is then acted upon by means of a hydrostatic pump 8 through the connecting line 7 with the bentonite suspension, which was previously prepared in a lump-free and compressible manner by a cement agitator and a mixing unit.

The pump 8 generates a pressure of up to 250 bar, which, however, has dropped to approximately 20-50 bar due to friction losses in the connecting line 7 at the nozzle opening.

Using the bentonite mud is now the sheet pile element 3a by means of a feed-controlled vibration bears 4 hz with a frequency of 30 to 50, preferably vibrated at 40 Hz vertically into the ground, the vibration and acoustic emission computer assistance is continuously monitored and controlled.

The flushing lance 5 is removed from the now vibrated sheet pile element 3 b, so that it is available again for introducing the next element.

Claims (7)

1. A method for the introduction of planks, in particular sheet piles or duct boards into the ground with the help of a vibrating bear, characterized in that the planks ( 4 ) the planks (simultaneously) using a thixotropic bentonite suspension as a lubricant and detergent and a low-frequency to high-frequency vibrating bear ( 4 ) 3 a, b) are driven into the ground ( 1 ). 2. The method according to claim 1, characterized in that the bentonite suspension with the aid of at least one flushing lance ( 5 ) attached to the planks ( 3 a, b) in the lower region of the planks ( 3 a, b) into the soil ( 1 ) is pressed. 3. The method according to claim 1 or 2, characterized in that holes with diameters of 150-400 mm are placed before the introduction of the planks ( 3 a, b) to relax the soil ( 1 ). 4. The method according to any one of the preceding claims, characterized in that the vibration bear ( 4 ) is operated at a constant frequency of 30 to 50 Hz and a permanent feed force control. 5. The method according to any one of the preceding claims, characterized in that the Bentonite suspension compressible and without lump formation is processed. 6. The method according to any one of the preceding claims, characterized in that the planks ( 3 a, b) by the thixotropic property of the bentonite suspension in conjunction with the high-frequency vibration of the vibrating bear ( 4 ) and permanent computer-controlled control of the emitted vibrations via continuous measuring points can be introduced into the soil ( 1 ) with low vibration. 7. The method according to any one of the preceding claims, characterized in that the bentonite suspension solidifies after vibrating and forms a compacted subsoil ( 1 ).