Method and apparatus for layer-by-layer filling and compacting cohesive building materials in layers in boreholes

Abstract

A method is used for the layer-by-layer filling and compaction of cohesive building materials, in particular of cohesive earth building materials, in at least one borehole near the surface. The cohesive building material is introduced into the at least one borehole and is compacted layer-by-layer using a conveying device comprising a stuffing piston driven by means of a push chain drive.

Claims

1. A method for layer-by-layer filling and compaction of cohesive building materials, in particular of cohesive soil building materials, in at least one borehole near a surface, the method comprising: introducing the cohesive building material into the at least one borehole; and compacting the cohesive building material layer-by-layer using a conveying device including a push chain drive and a stuffing piston driven by means of the push chain drive.

2. The method according to claim 1, wherein: the at least one borehole is lined with a protective tube; and the cohesive building material is filled into the protective tube in portions.

3. The method according to claim 2, wherein the protective tube is withdrawn from the borehole step by step during the filling of the borehole with the cohesive building material in dependence on the quantity of cohesive building material introduced.

4. The method according to claim 2, wherein the stuffing piston of the conveying device, after filling a first portion of the cohesive building material into the borehole: pushes the cohesive building material through the protective tube to a bottom of the borehole; and compacts the cohesive building material by a back-and-forth movement of the stuffing piston.

5. The method according to claim 1, wherein the stuffing piston of the conveying device, after filling a first portion of the cohesive building material into the borehole: pushes the cohesive building material in the borehole to a bottom of the borehole; and compacts the cohesive building material by a back-and-forth movement of the stuffing piston.

6. The method according to claim 1, wherein after compacting a first portion of the cohesive building material in the at least one borehole: the stuffing piston is moved out of the borehole, a further portion of the cohesive building material is filled into the borehole, the stuffing piston is reintroduced into the borehole; and the further portion of the cohesive building material is compacted by movement of the stuffing piston.

7. The method according to claim 1, wherein the cohesive building material for filling and compacting boreholes comprises: at least one absorbent in the form of a hydrogel; and compactable soil building material.

8. The method according to claim 7, wherein the compactable soil building material is selected from swellable clay minerals, excavated soil or excavated drilling material.

9. The method according to claim 7, wherein the compactable soil building material comprises swellable clay minerals, the method further comprising producing the cohesive building material, including: producing the hydrogel from a crosslinked polyacrylate and water; and adding a granulate of the swellable clay minerals to the hydrogel with mixing, whereby the granulate is wetted with the hydrogel.

10. The method according to claim 9, wherein the cohesive building material is producible from a mixture that contains: approximately 60 wt. % of the swellable clay mineral; approximately 0.2 wt. % of the hydrogel; and approximately 39.8 wt. % of water.

11. The method according to claim 9, wherein the cohesive building material has a solid, crumbly consistency and a moisture content of 15% to 50% water content.

12. The method according to claim 7, wherein the hydrogel is an acrylic-based hydrogel.

13. The method according to claim 7, wherein the compactable soil building material is a swellable clay mineral selected from the group consisting of bentonite, montmorillonite, kaolinites, smectites, illites, chlorites and mixtures thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The solution is explained in detail below by means of examples with reference to the figures.

(2) FIG. 1 shows a first schematic representation of the present method.

(3) FIG. 2 shows a second schematic representation of the present method.

(4) FIG. 3 shows a schematic representation of an embodiment of the push chain unit used in the present case.

(5) FIG. 4 shows a schematic representation of an embodiment of the present conveying device.

(6) FIG. 5 shows a schematic representation of a further embodiment of the present conveying device.

DETAILED DESCRIPTION

(7) FIG. 1 shows the process steps for the first filling of a borehole. The cohesive building material 18 is produced in a shaft mixer or rotary mixer and filled in portions into the filling tube 15 or protective tube of the borehole (step a).

(8) The stuffing piston 14, which is connected to the push chain 17 of the backfilling machine, pushes the building material through the filling pipe 15 to the bottom of the borehole. The push chain 17 is the drive unit of the machine, it pushes and pulls the stuffing piston 14. The filling pipe 15 is pulled out of the borehole as the backfilling progresses. A first layer of compacted backfill 19 is formed at the bottom (step b).

(9) FIG. 2 shows the further steps a)-c), which lead to a layer-by-layer filling of the borehole and compaction of the cohesive building material in the borehole. The push chain 17 with the stuffing piston 14 is moved out of the filling tube 15, the filling tube 15 is filled with the next portion of sealing material 18, and the stuffing piston 14 is reinserted into the filling tube 15.

(10) This process of filling in portions and compacting the cohesive building material 18 in the borehole is repeated until the borehole is completely filled and is flush with the ground surface or ground edge.

(11) FIG. 3 schematically shows an embodiment of the push chain unit 13 according to the solution. This push chain unit 13 comprises a push chain 17 with a push chain drive and a stuffing piston 14 driven by means of the push chain drive.

(12) FIG. 4 schematically shows an embodiment of the filling device 10 according to the solution comprising the push chain unit 13 shown in FIG. 3 with stuffing piston 14 and filling tube 15.

(13) The push chain unit 13 is part of a mounting frame which is arranged (horizontally) on a chain-driven transport means 11. For this purpose, a mounting kit (not shown) is arranged on the transport means, which makes it possible to move the push chain unit located on it in a swivelling and laterally extendable manner (along the X/Y axis).

(14) The push chain unit can have a vertical height adjustment (along the Z-axis) up to 2 m above the top edge of the terrain. The height adjustment makes it possible for the pulled filling pipe 15 to be easily turned down when the stuffing piston 14 is at the upper stop.

(15) The receiving frame 12 is connected to a rotation device 16, e.g. tiltrotator. Such a tiltrotator 16 enables a quick detachment of the receiving frame 12 including the push chain unit 13 from the transport means 11, so that an application as a mono unit on an excavator is possible.

(16) FIG. 5 schematically shows a further embodiment of the filling device 10 according to the solution, comprising the push chain unit 13 shown in FIG. 4 with stuffing piston 14 and filling tube 15, which is connected to the receiving frame 12. In contrast to the embodiment in FIG. 5, the receiving frame 12 with the push chain unit 13 is arranged vertically on a piece of construction equipment as a means of transport 11.

(17) The construction equipment shown in FIG. 5 also has a swivelling lifting device 20. This makes it possible to transport the conveying device on the construction equipment to the vicinity of the filling point, to position the conveying device comprising the receiving frame 12, the push chain unit 13 with the stuffing piston 14 and the filling pipe 15 above the borehole using the swivelling lifting device.

(18) A jaw gripper 21 is used to pull the filling pipe out of the borehole. The jaw gripper 21 grips the filling pipe to be pulled, pulls the filling pipe and turns the filling pipe off after pulling it out, e.g. at the screw thread.

Example 1: Compaction Method for a Borehole from the Explosive Ordnance Sounding

(19) The explosive ordnance explorer drills boreholes of 100-130 mm diameter in a grid of approx. 1.201.20 m, usually 6 m deep. After drilling, the explorer inserts the exploratory protection tube into the borehole. The exploratory protection pipe is a PE or PVC pipe, usually 56 mm in diameter and 6 m long, which can also consist of screwed segments.

(20) The explorer guides a magnetically sensitive measuring instrument on a cable into the protective pipe to the deepest point of the borehole. After the measurement is completed, the explorer leaves the borehole cased until the backfiller fills the borehole.

(21) The all-terrain backfilling machine, driving on caterpillar tracks, is positioned above the borehole. The exploratory protection pipe, which was previously inserted into the borehole, has a slightly larger diameter of 94/104 mm (inside/outside) and consists of screwed-together segments, each 1.50 m long, and is filled with a quantity of sealing material that can be determined by means of a dozing technique (pouring chute, screw conveyor, slide gate or similar). The exploratory protection pipe becomes the filling pipe here.

(22) The stuffing piston, which is attached to the push chain of the backfilling machine by means of a joint, is inserted into the filling pipe and driven with the push chain. This pushes the building material through the filling pipe until the deepest part of the borehole is reached. The control technology of the push chain drive measures the increasing counter pressure at the respective position of the stuffing piston by means of sensors (pressure sensor) and switches from fast travel to slow travel=compaction. The control technology carries out a stuffing movement of the stuffing piston by suitable back-and-forth movement and in this way compacts the cohesive earth material.

(23) As the layer-by-layer filling and compaction progresses, the filling pipe is pulled. This means: Compaction takes place outside (=below) the filling pipe, i.e. at the deepest point of the borehole.

(24) The push chain with stuffing piston is moved out of the filling tube, the filling tube is filled with the next portion of sealant, the stuffing piston is reinserted into the filling tube.

(25) Every calculated 3 layers, a segment of the filling pipe is unscrewed. With a pipe length of 6 m (corresponds to the borehole depth), this results in 12 trips of the push chain and layers of 50 cm backfilling distance and compaction each. At the end, the borehole is filled compacted layer by layer, 6 m borehole depth then has 12 compacted layers of 50 cm each.

(26) Travel time of the push chain without compaction travel (assumption: travel down=same length as pulling time)

(27) TABLE-US-00001 Travel of push chain 25 cm/sec Pushing time Pulling Total No. cm (sec) time time 1 600 24 24 48 2 550 22 22 44 3 500 20 20 40 4 450 18 18 36 5 400 16 16 32 6 350 14 14 28 7 300 12 12 24 8 250 10 10 20 9 200 8 8 16 10 150 6 6 12 11 100 4 4 8 12 50 2 2 4 Total travel time (sec) 312

(28) The sum of the travel times of the push chain for a 6 m deep borehole and 12 layers takes around 300 seconds, i.e. around 6 minutes. This is quite plausible, the time budget for the entire backfilling is 15 minutes per borehole.

Example 2: Binding Building Material/Sealing Material

(29) Recipe:

(30) 1 tonne of building material consists of: 60%=600 kg swellable clay (granulate grain size 1 . . . 16 mm, better 5 . . . 16 mm) 39.8%=398 litres of water 0.2%=2.0 kg hydrogel powder

(31) The building material mixture should be prepared on site shortly before installation. Perhapsbut we have not yet tested thisthe mixture can also be delivered ready-mixed (as with concrete in a truck mixer).

(32) Manufacture:

(33) Step 1: Place the hydrogel powder according to the solution in a stirred container/stirring machine/mixer in a quantity of 0.2% of the total quantity of building material.

(34) Step 2: Add water approx. 40% in relation to the quantity of building material and mix/stir slowly (do not mix colloidally or disperse as with Ultraturrax!) until a no longer dripping, almost cut-resistant, slippery yet crumbly gel results.

(35) Step 3: Add clay granulate corresponding to 60% of the total building material quantity and mix by stirring.

(36) Result: The clay granules are irregularly surrounded by water-filled but solid particles (they look like shredded gummy bears). According to the solution, these water-gel particles release the water under pressure, thus the water gets into the swellable clay, which thus swells and becomes a dense, homogeneous clay mass.