EP1942247B1 - Method and apparatus to drill in the soil by displacement - Google Patents

Abstract

The method involves driving the drill string (10) in the ground (3) in a rotating manner, where the drill string has a cross sectional large displacement area (20) in its sub area. The operating parameters are detected while driving the drill string in the ground. The operating parameters are used for determining the load-carrying capacity of the drilling (1). An independent claim is also included for a device for building a drilling in the ground by displacement boring.

Description

The invention relates to a method for creating a bore in the ground by positive displacement drilling in which a drill string, which has at least a cross-section enlarged displacement in a lower region, is rotationally retracted into the ground, operating parameters of the drill string during retraction of the drill string are detected in the ground and the operating parameters are used to determine the carrying capacity of the bore, according to the preamble of claim 1.

The invention further relates to a device for making a hole in the ground by positive displacement drilling according to the preamble of claim 8. Such a device is formed with a drill string having in a lower region at least a cross-section enlarged displacement, and a drive means for rotational driving and axial displacement the drill string, wherein means are provided for detecting operating parameters of the drill string during axial retraction of the drill string in the ground, and wherein a computing device is provided, which sets the operating parameters for determining the carrying capacity of the bore in a mathematical relationship.

A generic method and a generic device are for example from the EP 1 277 887 A2 known.

In a known Verdrängerbohrverfahren a drill string, which has a displacement area in the region of its bottom end, introduced into the soil. In this displacement region of the drill string is formed larger diameter compared with arranged below drill string areas. In the displacer area, pending drilling material is displaced radially with respect to the drill string while forming a cavity and compressing adjacent floor areas. In the resulting Cavity can be introduced a filler to form a foundation element. Verdrängerbohren go for example from the DE 103 44 353 A1 and the DE 42 20 976 C1 out.

For carrying capacity determination, ramming probing, for example the "Standard Penetration Test" (SPT), is known. The Standard Penetration Test introduces a standardized reaming probe into the ground and measures the number of ramming strokes required to insert the probe a certain distance. By calculating the determined number of impacts with empirical factors based on the soil type, the limit load capacity of piles can be estimated. In a positive displacement drilling method, however, such a procedure can be comparatively complicated because, in addition to the drilling device, a piling device must also be provided. In addition, the accuracy for certain applications can not be sufficiently high.

The EP 0 842 329 B1 discloses a drilling method in which pending soil material is conveyed by means of a drilling auger along a drill pipe, without being given a radial displacement. It is intended to determine the rotational speed, the penetration rate and / or the torque on the auger and to control such that the screw flights are loaded with soil material derived from the screw tip. In particular, the penetration rate should be adapted to the conveying speed of the auger, that neither too much material is promoted and threatens clogging of the screw flights, still too little material is promoted and threatens collapse of the well.

The EP 1 229 172 A1 describes a drilling process in which a drilling machine is equipped with sensors to determine the dynamic properties of the drilling tool. The readings of these sensors are stored for consecutive depths. For each depth, at least one variable representing the quality of the soil is calculated from the stored measurements.

The EP 0 401 119 A1 discloses another drilling method in which parameters are recorded.

The object of the invention is to provide a Verdrängerbohrverfahren and Verdrängerbohrvorrichtung, which allow in a particularly simple and economical way, the creation of wells with known carrying capacity.

The object is achieved by a method having the features of claim 1 and an apparatus having the features of claim 8. Preferred embodiments of the method are indicated in the dependent claims.

In the method according to the invention, it is provided that operating parameters of the drill string are detected during retraction of the drill string into the soil and that the operating parameters are used to determine the carrying capacity of the drill hole.

The invention is based on the finding that there is a relationship between the operating parameters prevailing when introducing a positive displacement drilling tool into the ground and the carrying capacity of the resulting bore. Among other things, this relationship may be due to the fact that during positive displacement drilling a targeted radial displacement and thus compression of the surrounding soil material takes place, wherein the compression properties in turn are related to the load capacity.

According to the invention, the load-carrying capacity is determined on the basis of measurements taken directly during the production of the displacement bore on the positive displacement drilling tool. The elaborate sinking special exploratory drilling by means of independent probing devices can thus be omitted, so that according to the invention a particularly low cost and a particularly high efficiency are given. In addition, since the load capacity data can be determined directly on the actual bore itself and need not be determined at probing sites spaced from the bore, a particularly accurate load capacity determination is possible according to the invention, which reflects the soil conditions of the actual well particularly well.

Suitably, a cavity formed in the bottom when retracting the drill string is filled with a particularly hardenable filling material, whereby a foundation element can be obtained. At the given carrying capacity it may be in this case to the carrying capacity of the foundation element act. The filling can take place during and / or after retraction of the drill string.

According to the invention, at least the torque on the drill string, the penetration depth of the drill string per revolution and in particular the penetration force of the drill string are used as operating parameters. This allows a particularly accurate characterization of the soil durchörterten and thus a particularly accurate determination of the carrying capacity. It is also possible to use further measured quantities which are related to at least one of the mentioned measured quantities for the purpose of determining the aforementioned measured variables. For example, the hydraulic pressure can be determined on a hydraulic rotary drive for the drill string and from this the torque can be determined on the drill string.

It is further provided that, to determine the carrying capacity of the bore, a quotient of the torque on the drill string and the penetration depth of the drill string per revolution is formed and from this a load capacity characteristic number is determined.

sein:The capacity index α can be a function f of the quotient of the torque M on the drill string to the penetration depth of the drill string per revolution $\frac{\mathrm{\Delta }d}{n}$

be:

n $$\alpha =\mathrm{f}\left(\frac{M}{\left(\frac{\mathrm{\Delta }d}{n}\right)}\right)$$

sein: $$\alpha =\frac{M}{\left(\frac{\mathrm{\Delta }d}{n}\right)}$$

In particular, the code α can directly the ratio of the torque M, which is applied to the drill string, to the penetration depth per revolution $\frac{\mathrm{\Delta }d}{n}$

be: $$\alpha =\frac{M}{\left(\frac{\mathrm{\Delta }d}{n}\right)}$$

The code α can, for example, characterize the soil type of the soil layer that has been passed through.

According to the invention, it can be provided that the determined operating parameters and / or the determined load capacity index for determining the carrying capacity are compared with a value table. As a result, a particularly simple determination of the carrying capacity is made possible. The value table can be determined empirically, for example.

A particularly simple and economic load-bearing capacity determination according to the invention is further given by the fact that to determine a mapping rule between the operating parameters and the load capacity and / or a mapping rule between the load capacity index and the carrying capacity in advance test wells are carried out in soil layers with known properties. By comparing the operating parameters determined in unknown soil layers and / or the load capacity index determined here with the values determined during the test bores, it is possible to conclude on the carrying capacity of the unknown soil layer. In particular, the carrying capacity of the unknown soil layer can be equated with the carrying capacity of a known soil layer, if there is at least approximately agreement between the operating parameters and / or the capacity index. The test bores thus serve to calibrate the method according to the invention and / or the device according to the invention. The properties of the soil layers in which the test bores are made, in particular their carrying capacity, are preferably determined by measurement. For this purpose, any known method, such as a Rammsonondierungsverfahren be used.

For a particularly accurate characterization of the soil which has been passed through, it is advantageous that at least one of the operating parameters is detected in the soil as a function of the penetration depth of the drill string. Preferably, all operating parameters used to determine the carrying capacity are recorded as a function of depth. Depth-dependent detection makes it possible to determine the position and / or the thickness of viable layers. In particular, the penetration depth-dependent operating parameter can be used to determine a depth profile of the load capacity. For example, the load index over the penetration depth of the drill string can be determined, whereby the depth profile of the load capacity can be characterized.

Furthermore, it is advantageous according to the invention that at least one of the operating parameters for previously determined Eindrücktiefebereiche of the drill string is determined in the soil. The Eindrücktiefebereiche can be for example about 3 meters. By such a regional measurement, the effort in the data acquisition can be reduced. A regional determination of the operating parameters also brings about a certain averaging, so that short-term fluctuations in the operating parameters, which result from local inhomogeneities in the soil, are not excessive in importance.

In order to determine the carrying capacity from the operating parameters and / or to determine the load capacity index, a computing device, in particular a computer, is suitably provided, which is in signal connection with receivers for the operating parameters and / or for measured variables which are related to the operating parameters.

It is particularly advantageous that an end depth of the bore is set as a function of the determined operating parameters, in particular of the determined load-bearing capacity index. For example, it may be provided to drill automatically until a bottom layer with a previously determined limit load capacity has been reached.

In particular, for a particularly high rate of drilling progress is provided that the drill string has at least one delivery spiral in the region of the displacement. The conveyor coil is provided between the drill string tip and the displacer section and may serve to excavate soil material impinging on the drill string and to convey it to the displacer section.

In the device according to the invention means are provided for detecting operating parameters of the drill string during axial retraction of the drill string in the ground and a computing device which sets the operating parameters for determining the carrying capacity of the bore in a mathematical relationship.

A device according to the invention can be set up in particular for carrying out the method according to the invention, whereby the advantages explained in this connection can be achieved.

Fig. 1

eine Seitenansicht einer erfindungsgemäßen Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens.

The invention will be explained in more detail below with reference to preferred embodiments, which are shown schematically in the accompanying drawing. This shows schematically:

Fig. 1

a side view of a device according to the invention for carrying out the method according to the invention.

An embodiment of a Verdrängerbohrvorrichtung invention is in Fig. 1 shown. The device has a drill string 10, which can be rotated in the direction of the arrow by means of a drive device 41 and can be moved axially in the direction of the arrow. Near its tip, the drill string 10 has a displacer portion 20 in which the drill string 10 is made larger in diameter as compared to the portions above and below. On the tip of the drill string 10 facing side of the displacer 20, a first conveyor coil 11 is arranged on the drill string 10. On the side of the displacer region 20 facing away from the tip of the drill string 10, a second conveying spiral 12 is provided on the drill string 10.

When rotating retracting the drill string 10 in the bottom 3 10 upcoming soil material is processed at the top of the drill string. This processed soil material is from the lower conveyor coil 11 along the drill string 10 in the Displacer 20 promoted. Due to the increase in diameter of the drill string 10 in the displacement region 20, the axially conveyed processed soil material is displaced radially to the drill string 10 and pressed into adjacent soil areas. Thus, a hole 1 is created in the bottom 3, without that processed soil material is apparent and accumulated as excavation.

The first conveyor spiral 11 arranged in opposite directions upper conveyor coil 12 is used for supplying soil material, which breaks from upper bore areas in the bore 1, to the displacement area 20, where it is also pressed radially into adjacent floor areas.

In an upper region of the drill string 10, this is smooth, that is formed without a conveyor spiral. An emergent conveyor coil is not required in a Verdrängerbohrverfahren because the processed soil remains in the ground.

On the drill string 10, a pick-up device 51 is provided, with which the penetration depth of the drill string 10 per rotation of the drill string 10 can be determined. A further pick-up device 52 is provided on the drive device 41 and serves to determine the torque with which the drill string 10 is acted upon by the drive device 41. In addition, with the pick-up device 52, the axially directed penetration force on the drill string 10 can be determined. Both receiver devices 51 and 52 are in signal connection with a computing device 53, in particular in line connection. This computing device 53 is used to determine the carrying capacity of the bore 1 from the recorded torque, the recorded penetration depth per revolution and the recorded penetration force. In particular, the computing device 53 can be used to determine a load capacity index α from the stated values.

In the illustrated embodiment, the bottom 3 intersected by the bore 1 has three superimposed bottom layers 4, 4 ', 4 "with different load capacities Accordingly, the computing device 53 determines a different load capacity index α when stepping through the bottom layers 4, 4', 4" , α ', α ".

Claims (8)

1. Method for making a drill-hole (1) in the soil (3) by means of displacement drilling, in which

   - a drill string (10), which has in a lower area at least one cross-sectionally enlarged displacement portion (20) and between a drill string tip and the displacement portion (20) at least one conveyer flight (11, 12), is driven into the soil (3) in a rotating manner,

   - operating parameters of the drill string (10) are detected on driving the drill string (10) into the soil (3), and

   - the operating parameters are used to determine the load-carrying capacity of the drill-hole (1),

   characterized in that
   at least the torque on the drill string (10) and the penetration depth of the drill string (10) per revolution are used as operating parameters,
   in that in order to determine the load-carrying capacity of the drill-hole (1) a quotient is generated of the torque on the drill string (10) and the penetration depth of the drill string (10) per revolution and from this a load-carrying capacity characteristic (α) is ascertained, and
   in that in order to ascertain an assignment rule between the load-carrying capacity characteristic (α) and the load-carrying capacity, test drillings in soil layers with known properties are carried out beforehand.
2. Method according to claim 1,
   characterized in that
   the penetration force of the drill string (10) is used as an operating parameter.
3. Method according to any one of the preceding claims,
   characterized in that
   the ascertained operating parameters and/or the ascertained load-carrying capacity characteristic (α) are compared with a table of values in order to determine the load-carrying capacity.
4. Method according to any one of the preceding claims,
   characterized in that
   at least one of the operating parameters is detected as a function of the penetration depth of the drill string (10) in the soil (3), in which case the operating parameter depending on the penetration depth is used in particular for determining a depth profile of the load-carrying capacity.
5. Method according to any one of the preceding claims,
   characterized in that
   at least one of the operating parameters is ascertained for previously determined penetration depths of the drill string (10) in the soil (3).
6. Method according to any one of the preceding claims,
   characterized in that
   a final depth of the drill-hole (1) is set as a function of the ascertained operating parameters.
7. Method according to any one of the preceding claims,
   characterized in that
   a hollow space formed in the soil (3) during driving of the drill string (10) is filled in particular with a hardening filling material and a bored pile is formed.
8. Device for making a drill-hole (1) in the soil (3) by means of displacement drilling, in particular for carrying out the method according to any one of the preceding claims, comprising

   - a drill string (10) which has in a lower area at least one cross-sectionally enlarged displacement portion (20) and between a drill string tip and the displacement portion (20) at least one conveyer flight (11, 12) and

   - a driving device to drive the drill string (10) in a rotating manner and for axial dis placement thereof,

   - wherein means are provided for detecting operating parameters of the drill string (10) during axial driving of the drill string (10) into the soil (3) and

   - wherein a computing device (53) is provided which puts the operating parameters into a mathematical relation in order to determine the load-carrying capacity of the drill-hole (1),

   characterized in that
   the means for detecting operating parameters are adapted to detect at least the torque on the drill string (10) and the penetration depth of the drill string (10) per revolution as operating parameters,
   in that in order to determine the load-carrying capacity of the drill-hole (1) the device is adapted to generate a quotient of the torque on the drill string (10) and the penetration depth of the drill string (10) per revolution and to ascertain from this a load-carrying capacity characteristic (α), and
   in that the device is calibrated by means of test drillings which have been carried out beforehand in soil layers with known properties in order to ascertain an assignment rule between the load-carrying capacity characteristic (α) and the load-carrying capacity.

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