EP3792403A1 - Method for producing a full displacement drill bit, screw base assistance system for guiding a screw operation in such a method, and software for such a screw assistance system - Google Patents

Abstract

The invention relates to a method for producing a full displacement bored pile (10), a database (30) with sample data (32) of pile test loads being provided, the pile test loads being carried out on full displacement bored piles that were made by screws in different construction sites (22) - The sample data (32) for each of these full displacement bored piles include at least one torque that was used when screwing in the respective subsoil, and a load-bearing capacity of the full displacement bored pile; - a desired load-bearing capacity of the full displacement bored pile (10) to be produced is defined; - constant boundary conditions of a screwing process - the screwing process comprises that a pipe (12) with a cutting head (14), which is closed watertight with a foot tip (16), is screwed into a building ground (22); - at least one breakaway torque when screwing in a load-bearing Bottom layer of the ba - a ratio of load-bearing capacity and torque in the load-bearing soil layer is obtained from the sample data (32), on the basis of which the breaking torques are determined in connection with and / or as a function of the embedment depth; constant boundary conditions are maintained and the torque and the embedment depth are measured; the screwing process is aborted when the measured torque reaches the abortion torque in connection with and / or as a function of the measured embedment depth. The invention also relates to a screwing assistance system (40) for guiding a screwing process in such a method and software for such a screwing assistance system (40).

Description

The invention relates to a method for producing a fully displacement bored pile, a screwing assistance system for carrying out a screwing process in such a method, and software for such a screwing assistance system.

In the prior art, screw piles according to DIN EN 12 699 are generally known. These screw piles are also referred to as full displacement bored piles or displacement piles and are described, for example, in the document " Recommendations of the working group "Pfähle": EA-Pfähle ", Berlin: Ernst & Sohn, 2007, published by the Deutsche Gesellschaft für Geotechnik eV, ISBN 978-3-433-01870-5, chapter 2.2.4 . This document as a whole is hereinafter also referred to as "EAP".

Such full displacement bored piles are often used in urban areas so as not to disturb residents and not to damage sensitive structures in the vicinity. These full displacement bored piles are produced by rotating a steel pipe, to which an exchangeable cutting head is attached, is pressed into the subsoil and thus screwed into the subsoil. The soil is laterally displaced and compacted by the cutting head. The outside dimensions of the cutting head determine the pile diameter. The cutting head is sealed watertight with a lost toe, which will remain in the screw hole after the pile has been completed. The cutting head and the pipe are screwed vibration-free into the subsoil using a rotary drive with simultaneous vertical contact pressure. This contact pressure is measured as it is screwed in and compared with subsoil outcrops that have previously been created for the respective construction site and include, for example, drilling profiles and / or exploration diagrams. After the target depth has been reached, a reinforcement cage is lowered into the pipe. The pipe and a storage container placed on top are filled with concrete. The pipe and the cutting head are screwed backwards out of the subsoil. The tip of the foot is released from the cutting head and the cutting head forms the post when it is unscrewed. The concrete column in the pipe and the container fills the with its large static overpressure from the cutting head released cavity immediately with concrete. This creates a helical concrete bead around the pile shaft in the subsoil. The concrete bead is, for example, 5 cm thick, which means that its outer radius is 5 cm larger than the outer radius of the pile shaft.

In the prior art, three procedures for dimensioning such fully displacement bored piles are also known, which are described by way of example in EAP, Chapter 5.

The first approach uses evaluations of pile load tests that were carried out on the respective construction site.

Pile test loads are generally known and are described, for example, in DIN

• die äußere Tragfähigkeit von Einzelpfählen oder Pfahlgruppen zu ermitteln;
• die Bemessungsgrundlagen festzulegen;
• die Bemessungsgrundlagen zu überprüfen;
• die Eignung eines Pfahlsystems für die vorliegenden Baugrundverhältnisse zu prüfen;
• die Einhaltung von vorbestimmten maßgebenden Verschiebungsgrenzwerten für die Gebrauchstauglichkeit von Bauwerken nachzuweisen;
• die innere Tragfähigkeit von Pfählen zu überprüfen;
• die Ausführungsqualität zu kontrollieren.

EN 1997-1, DIN 1054 and EAP. Such pile load tests are carried out for different purposes, for example to:

• to determine the external load-bearing capacity of individual piles or pile groups;
• determine the assessment bases;
• to review the tax bases;
• to check the suitability of a pile system for the existing subsoil conditions;
• to prove compliance with predetermined decisive displacement limit values for the serviceability of structures;
• to check the internal load-bearing capacity of piles;
• control the quality of execution.

In such a pile test loading, the pile to be examined is loaded and relieved cyclically, the pile load being increased in stages. The vertical movement of the pile is recorded throughout the process. These settlements and uplifts enable very differentiated statements to be made about the load-bearing behavior and load-bearing capacity of the pile and the nature of the soil.

The second approach uses a soil survey that was prepared for the respective construction site. The dimensioning is carried out using the respective lower values from the applicable EAP diagrams and tables.

According to EAP, Chapter 5.4.3 ff, these lower values correspond to the 0.1 quantile - that in EAP is designated as "10% -fractile" - the pile resistances, which have been derived from the empirical evaluations of the pile test loads used.

The third approach uses evaluations of pile test loads that have already been carried out on at least one other construction site, the soil assessment of which is similar to the soil assessment of the respective construction site. The dimensioning is carried out using the respective upper values from the applicable EAP diagrams and tables.

The accuracy with which the load-bearing capacity of the individual full displacement bored piles can be determined is usually better with the first approach than with the third approach and with the third approach better than with the second approach.

• eine Datenbank mit Probedaten von Pfahlprobebelastungen bereitgestellt wird, wobei die Pfahlprobebelastungen an Vollverdrängungsbohrpfählen, die in unterschiedlichen Baugründen durch Schrauben hergestellt wurden, durchgeführt wurden;
• die Probedaten für jeden dieser Vollverdrängungsbohrpfähle wenigstens ein Drehmoment, das beim Schrauben in dem jeweiligen Baugrund verwendet worden ist, und eine Tragfähigkeit des Vollverdrängungsbohrpfahles umfassen;
• eine angestrebte Tragfähigkeit des herzustellenden Vollverdrängungsbohrpfahles definiert wird;
• konstante Randbedingungen eines Schraubvorgangs definiert werden;
• der Schraubvorgang umfasst, dass ein Rohr mit einem Schneidkopf, der mit einer Fußspitze wasserdicht verschlossen ist, in einen Baugrund geschraubt wird;
• wenigstens ein Abbruchdrehmoment beim Schrauben in einer tragfähigen Bodenschicht des Baugrunds ermittelt wird;
• aus den Probedaten ein Verhältnis von Tragfähigkeit und Drehmoment in der tragfähigen Bodenschicht gewonnen wird, anhand dessen die Abbruchdrehmomente in Zusammenhang mit und/oder in Abhängigkeit von der Einbindetiefe bestimmt werden;
• bei dem Schraubvorgang die konstanten Randbedingungen eingehalten werden und das Drehmoment und die Einbindetiefe gemessen werden;
• der Schraubvorgang abgebrochen wird, wenn das gemessene Drehmoment das Abbruchdrehmoment in Zusammenhang mit und/oder in Abhängigkeit von der gemessenen Einbindetiefe erreicht.

Against this background, the invention proposes, according to a first aspect, a method for producing a full displacement bored pile, wherein

• a database is provided with sample data from pile load tests, the pile test loads being carried out on fully displacement bored piles which were produced by screwing in different building sites;
• the sample data for each of these full displacement bored piles include at least one torque that has been used when screwing in the respective subsoil, and a load-bearing capacity of the full displacement bored pile;
• a desired load-bearing capacity of the full displacement bored pile to be produced is defined;
• constant boundary conditions of a screwing process are defined;
• the screwing process comprises that a pipe with a cutting head, which is sealed watertight with a foot tip, is screwed into a building ground;
• at least one demolition torque is determined when screwing in a stable soil layer of the subsoil;
• from the sample data, a relationship between load-bearing capacity and torque in the load-bearing soil layer is obtained, on the basis of which the demolition torques are determined in connection with and / or as a function of the embedment depth;
• the constant boundary conditions are maintained during the screwing process and the torque and the embedment depth are measured;
• the screwing process is aborted when the measured torque reaches the abortion torque in connection with and / or as a function of the measured embedment depth.

The proposed method enables the local subsoil in which this pile is to be produced to be taken into account individually for each individual full displacement bored pile. This avoids the pile being made longer than would be necessary for the desired load-bearing capacity, or being made too short, although the subsoil is locally less load-bearing. This in turn prevents different spring stiffnesses and settlement of the individual piles, which would otherwise lead to undesirable stresses in the building built on them. In addition, this method makes it possible that the screwdriver used for the screwing process is not overstrained and is less subject to wear.

The load-bearing capacities included in the sample data are preferably those load-bearing capacities that result or have resulted from a defined settlement of the respective full displacement bored pile.

The desired load-bearing capacity is preferably that load-bearing capacity that results or will result from a defined settlement of the full displacement bored pile to be produced.

For the defined settlement, the value 0.1 · D is usually used, where D is the outside diameter of the pile shaft or the outside diameter of the concrete bead.

The embedment depth is the length of the pile section that is located in the load-bearing soil layer.

After the screwing process has been aborted, it is possible, for example, to continue in a known manner by lowering a reinforcement cage or other suitable reinforcement into the pipe, pouring concrete, and rotating the pipe and the cutting head backwards out of the subsoil and placing a toe with which the The cutting head was previously sealed watertight, remains in the screw hole.

• eine Bodenbeschaffenheit wenigstens eines Ortes ermittelt wird;
• die Probedaten entsprechend der ermittelten Bodenbeschaffenheit gefiltert werden, um das Abbruchdrehmoment zu ermitteln.

In one embodiment of this aspect it is specified that

• a soil condition of at least one location is determined;
• the sample data are filtered according to the determined soil properties in order to determine the demolition torque.

This location is preferably in the area of the construction site on which the full displacement bored pile is to be constructed.

In one embodiment of this aspect it is specified that the constant boundary conditions comprise at least parameters selected from a group comprising a cutting head type, an outer diameter of the pipe, a foot tip type, a longitudinal screwing speed, a rotational speed, a longitudinal extraction speed and a contact pressure.

This longitudinal screwing speed is the feed speed with which the cutting head and the pipe move downwards into the subsoil when screwing. This speed is the speed at which the cutting head and the pipe rotate when screwing into the subsoil. This longitudinal extraction speed is the retraction speed with which the cutting head and the pipe move upwards out of the subsoil when unscrewing. This contact pressure is the pressure with which the cutting head and the pipe are pressed against the subsoil when screwing.

In one embodiment of this aspect, it is specified that a minimum embedment depth of the fully displacement bored pile to be produced in the load-bearing soil layer and the demolition torque are used to determine the cancellation of the screwing process.

It is then preferably specified that the minimum embedment depth is a function of the demolition torque.

It is then preferably further specified that the function has at least the parameter load capacity. If required, the function can have further parameters that result, for example, from the boundary conditions.

In one embodiment of this aspect, it is specified that at least one of the termination torques corresponds to a predetermined quantile of the sample data. This quantile is for example the 0.1 quantile.

• eine Software, die eine Datenbank, eine Eingabeschnittstelle, eine Verarbeitungsebene und eine Ausgabeschnittstelle umfasst;
  wobei
• die Datenbank Probedaten umfasst;
• mittels der Eingabeschnittstelle eine angestrebte Tragfähigkeit des herzustellenden Vollverdrängungsbohrpfahles eingebbar ist;
• mittels der Verarbeitungsebene wenigstens ein Abbruchdrehmoment aus eingegebenen Daten und den Probedaten ermittelbar ist;
• mittels des Schraubassistenzsystems konstante Randbedingungen für den Schraubvorgang vorgebbar sind;
• mittels des Schraubassistenzsystems ein Drehmoment bei einem Schraubvorgang ermittelbar ist;
• mittels des Schraubassistenzsystems ein Abbrechen des Schraubvorgangs zumindest abhängig von dem ermittelten Drehmoment einleitbar ist.
  Bei einer Ausführungsform dieses Aspekts ist spezifiziert, dass
• eine Bodenbeschaffenheit wenigstens eines Ortes in das Schraubassistenzsystem eingebbar ist;
• die Probedaten entsprechend der Bodenbeschaffenheit filterbar sind, um die Abbruchdrehmoment zu ermitteln.

In addition, according to a second aspect, the invention proposes a screwing assistance system for guiding a screwing process in a method which is designed according to the first aspect, comprising

• software comprising a database, an input interface, a processing level and an output interface;
  in which
• the database includes sample data;
• a desired load-bearing capacity of the full displacement bored pile to be produced can be entered by means of the input interface;
• by means of the processing level, at least one termination torque can be determined from the data entered and the sample data;
• constant boundary conditions for the screwing process can be specified by means of the screwing assistance system;
• a torque during a screwing process can be determined by means of the screwing assistance system;
• the screwing assistance system can be used to initiate a termination of the screwing process at least as a function of the determined torque.
  In one embodiment of this aspect it is specified that
• a soil condition of at least one location can be input into the screwing assistance system;
• the sample data can be filtered according to the nature of the soil in order to determine the demolition torque.

In one embodiment of this aspect, it is specified that this soil condition and / or sample data that were determined during the screwing process can be stored in the database.

• eine Datenbank, eine Eingabeschnittstelle, eine Verarbeitungsebene und eine Ausgabeschnittstelle;
  wobei
• die Datenbank Probedaten aufweist;
• mittels der Eingabeschnittstelle eine angestrebte Tragfähigkeit des herzustellenden Vollverdrängungsbohrpfahles eingebbar ist;
• mittels der Verarbeitungsebene wenigstens ein Abbruchdrehmoment ermittelbar ist.

Furthermore, according to a third aspect, the invention proposes software for a screwdriving assistance system, which is designed according to the second aspect, comprising

• a database, an input interface, a processing level and an output interface;
  in which
• the database has sample data;
• a desired load-bearing capacity of the full displacement bored pile to be produced can be entered by means of the input interface;
• at least one termination torque can be determined by means of the processing level.

The explanations for one of the aspects of the invention, in particular for individual features of this aspect, also apply analogously to the other aspects of the invention.

In the following, embodiments of the invention are explained in more detail by way of example with reference to the accompanying drawings. The individual features resulting therefrom, however, are not restricted to the individual embodiments, but can be connected and / or combined with individual features described above and / or with individual features of other embodiments. The details in the drawings are only to be interpreted as explanatory, but not restrictive. The reference symbols contained in the claims are not intended to restrict the scope of protection of the invention in any way, but merely refer to the embodiments shown in the drawings.

FIG. 1

eine bevorzugte Ausführungsform eines Schraubassistenzsystems zum Führen eines Schraubvorgangs in einem Verfahren zum Herstellen eines Vollverdrängungsbohrpfahles.

The drawing shows in

FIG. 1

a preferred embodiment of a screwing assistance system for guiding a screwing process in a method for producing a full displacement bored pile.

In FIG. 1 a preferred embodiment of a screwing assistance system 40 according to the invention for guiding a screwing process in a method for producing a full displacement bored pile 10 on a construction site 20 is shown schematically. The method is designed according to a preferred embodiment and will be described in more detail below.

The tightening assistance system 40 includes software that includes a database 30 with sample data 32, an input interface, a processing level and an output interface.

By means of the input interface, a desired load-bearing capacity of the full displacement bored pile 10 to be produced as well as other required data can be entered.

By means of the processing level, a breaking torque can be determined from the entered load capacity and the further entered data as well as from the sample data 32. This determination is carried out according to the method.

The screwing assistance system 40 can be used to predetermine constant boundary conditions for the screwing process, a torque during a screwing process can be determined, and a termination of the screwing process can be initiated at least as a function of the determined torque.

By means of the output interface, the cancellation can be output to a screwdriver (not shown) that is used in the method.

In the following, the preferred embodiment of the method for making the full displacement bored pile 10 will be described.

The database 30 with the sample data 32 of pile test loads in different building sites 22 is provided. The current subsoil 22 of the construction site 20 comprises, for example, a first, upper soil layer 22.1, which is cohesive and has a low load-bearing capacity that is insufficient for the planned structure, and a second, lower soil layer 22.2, which is non-cohesive and a high one for the planned structure Structure has sufficient load-bearing capacity.

The sample data 32 include for each of these building sites 22 at least a torque that was used when screwing in this building site 22, and a load-bearing capacity of a full displacement bored pile 10 that was produced by this screwing.

A desired load-bearing capacity of the full displacement bored pile 10 to be produced is defined. In addition, constant boundary conditions of a screwing process that is to be carried out to produce the full displacement bored pile 10 are defined.

Furthermore, at least one breaking torque is determined when screwing in a load-bearing soil layer 22.2.

From the sample data 32, a ratio of load capacity and torque in the load-bearing capacity becomes Soil layer 22.2 obtained, on the basis of which at least the demolition torque is determined in connection with and / or as a function of the embedment depth.

In addition, the nature of the soil at at least one location 26 on construction site 20 is determined. The sample data 32 will then be filtered according to the determined soil condition in order to determine the abort torque.

The screwing process comprises that a pipe 12 with a cutting head 14, which is sealed watertight with a foot tip 16, is screwed into the subsoil 22.

The constant boundary conditions are maintained during the screwing process and the torque is measured.

The constant boundary conditions include, for example, the following parameters: the type of cutting head 14, the outside diameter of the tube 12, the type of foot tip 16, the longitudinal screwing speed, the rotational speed and the contact pressure.

The screwing process is aborted as soon as the measured torque reaches the abortion torque in connection with and / or depending on the embedment depth.

After the screwing process is aborted, the process continues, for example, by lowering a reinforcement cage (not shown) into the pipe 12, pouring concrete into the pipe 12 and into a storage container 18 placed on top, and finally the pipe 12 and the 14 cutting head are backwards out of the subsoil 22 unscrewed, the tip of the foot 16 remaining in the screw hole 24. The full displacement bored pile 10 is ready as soon as the concrete has hardened.

Claims (11)

Method for producing a full displacement bored pile (10), wherein - A database (30) is provided with sample data (32) of pile test loads, the pile test loads being carried out on fully displacement bored piles which were produced by screwing in different building sites (22); - The sample data (32) for each of these full displacement bored piles include at least one torque that was used when screwing in the respective subsoil, and a load-bearing capacity of the full displacement bored pile; - A desired load-bearing capacity of the full displacement bored pile (10) to be produced is defined; - constant boundary conditions of a screwing process are defined; - The screwing process comprises that a pipe (12) with a cutting head (14), which is closed watertight with a foot tip (16), is screwed into a building ground (22); - At least one breaking torque is determined when screwing in a stable soil layer of the subsoil (22); - A ratio of load-bearing capacity and torque in the load-bearing soil layer is obtained from the sample data (32), on the basis of which the demolition torques are determined in connection with and / or as a function of the embedment depth; - The constant boundary conditions are maintained during the screwing process and the torque and the embedment depth are measured; - the screwing process is aborted when the measured torque reaches the abortion torque in connection with and / or as a function of the measured embedment depth. The method of claim 1, wherein - a soil condition of at least one location (26) is determined; - The sample data (32) filtered according to the determined soil properties to determine the breakaway torque. Method according to one or more of claims 1 to 2, wherein the constant boundary conditions comprise at least parameters selected from a group comprising a cutting head type, an outer diameter of the pipe (12), a toe tip type, a longitudinal screwing speed, a rotational speed, a longitudinal extraction speed and a contact pressure. Method according to one or more of claims 1 to 3, wherein a minimum embedment depth in the load-bearing soil layer (22.2) and the breaking torque are used to determine the breaking off of the screwing process. The method of claim 4, wherein the minimum embedment depth is a function of the demolition torque. Method according to claim 5, wherein the function has at least the parameter load capacity. The method according to one or more of claims 1 to 6, wherein at least one of the termination torques corresponds to a quantile of the sample data. A screwing assistance system (40) for guiding a screwing process in a method which is designed according to one or more of claims 1 to 7, comprising - A software which comprises a database (30), an input interface, a processing level and an output interface;
in which - the database (30) comprises sample data (32); - A desired load-bearing capacity of the full displacement bored pile (10) to be produced can be entered by means of the input interface; - by means of the processing level, at least one termination torque can be determined from the data entered and the sample data (32); - Constant boundary conditions for the screwing process can be specified by means of the screwing assistance system (40); - A torque during a screwing process can be determined by means of the screwing assistance system (40); - The screwing assistance system (40) can be used to initiate a termination of the screwing process, at least as a function of the determined torque. Screwdriving assistance system (40) according to claim 8, wherein - A soil condition of at least one location (26) can be input into the screwing assistance system (40); - The sample data (32) can be filtered according to the nature of the soil in order to determine the demolition torques. Screwing assistance system (40) according to one or more of claims 8 to 9, wherein the soil condition and / or sample data (32) that were determined during the screwing process can be stored in the database (30). Software for a screwdriving assistance system (40), which is designed according to one or more of claims 8 to 10, comprising - A database (30), an input interface, a processing level and an output interface;
in which - the database (30) has sample data (32); - A desired load-bearing capacity of the full displacement bored pile (10) to be produced can be entered by means of the input interface; - At least one termination torque can be determined by means of the processing level.

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