Method for draining a section of the ground, draining apparatus and draining system

Abstract

A method (100) for draining a section of the ground is disclosed. The method comprises positioning (101) a draining apparatus (1) in the section of the ground, wherein the draining apparatus comprises an outer unit (3) and an inner unit (7) comprising an inner part (7.1) arranged to be positioned within the outer unit (3) and having a plurality of through holes (7.2) enabling water to flow into the inner part (7.1), wherein an inner space (4) between an outer surface (7.4) of the inner part (7.1) and an inner surface (3.2) of the outer unit (3) is created for a draining material to be placed within the inner space (4). The method further comprises providing (103) the draining material to the inner space (4) and removing (105) the outer unit (3) from the ground while keeping the inner unit (7) and the draining material positioned in the ground. A draining apparatus (1) and a draining system (10) are also disclosed.

Description

[0001] METHOD FOR DRAINING A SECTION OF THE GROUND, DRAINING APPARATUS AND DRAINING SYSTEM

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of draining. Particularly, the present disclosure relates to a method for draining a section of the ground, such as the bottom of a construction pit. The present disclosure further relates to a draining apparatus and to a draining system.

[0004] BACKGROUND

[0005] When starting a building project, such as for example building of a new house, or when service or replacement of pipes or other installations placed in the ground is required, it is necessary to perform digging in the ground. In some areas the ground water level may be high resulting in water to seep into the pit or the trench that has been excavated. In case of water leakages, that may be caused due to a broken water pipe, water flows out from the pipe into the ground. The accumulated water needs to be pumped out to enable further digging. Effective ground drainage is essential in construction and other fields where water accumulation can pose safety risks, cause delays, or increase project costs. It is a common procedure to use a water pump placed in the pit or the trench. One problem when working with wet ground masses is that the sides of a pit or a trench may collapse which make digging difficult and, in some situations, may be dangerous for an operator that may need to work in the pit or in the trench. Further, the water pump may become clogged making further pumping limited.

[0006] Efforts have been made to solve some of the above-mentioned problems resulting in draining apparatus comprising perforated pipes and pumps to pump the accumulated water. CN218713198U is an example of such an apparatus. The document describes a draining device comprising a perforated cylinder, a water pump and a water suction pipe for pumping the accumulated water.

[0007] One problem with the existing solutions is that the holes of perforated pipes or cylinders may become clogged which may impair the ability to collect water and pump out the accumulated water. A further problem with the existing solutions is that the operation of a draining device including positioning the device in the ground, operation in the ground and removal from the ground may be very demanding for an operator. Further attention is drawn to KR100437343B1 , disclosing a system and method for reinforcing soft ground by constructing a double vertical drainage structure. A steel pipe is press-fitted into the ground, a porous tube is positioned inside the steel pipe, and sand is introduced to form a sand column around the porous tube. After withdrawal of the steel pipe, the resulting structure provides an internal porous drain within an external sand column, thereby enabling pore water to be discharged for ground reinforcement.

[0008] Additionally, JP2023019286A presents a ground drainage structure intended for sports fields and similar grounds. The device includes a vertical drainage pipe connected to an underground drainage path, and an inner pipe with side drainage ports that can be lifted to the ground surface for use. When not in use, the inner pipe is hidden below the ground surface and covered with soil, thereby reducing the risk of clogging with foreign matter.

[0009] However, even though the solutions presented in CN218713198U, KR100437343B1 and JP2023019286A have a positive impact on water removal and in some cases provide protection against soil collapse, they still rely on permanent structures or relatively complex installation and operation. Accordingly, there remains room for further improvements in relation to simplified installation, reusability of components, and more reliable long-term drainage, further heightening efficiency and safety in construction projects.

[0010] SUMMARY

[0011] It is an objective of the present disclosure to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks. It is a further objective of the present disclosure to provide a solution for optimizing draining of a section of the ground in terms of efficiency, reliability and / or safety.

[0012] These objectives and others are at least partly achieved by the method, the apparatus and the system according to the independent claims, and by the embodiments according to the dependent claims.

[0013] According to a first aspect, the disclosure relates to a method for draining a section of the ground, such as the bottom of a construction pit. The method comprises the step of positioning a draining apparatus in the section of the ground. The draining apparatus comprises an outer unit and an inner unit comprising an inner part arranged to be positioned within the outer unit and having a plurality of through holes enabling water to flow into the inner part to be collected within the inner part. The inner part is positioned within the outer unit to create an inner space between an outer surface of the inner part and an inner surface of the outer unit for a draining material to be placed within the inner space. The method further comprises the steps of providing the draining material to the inner space and removing the outer unit from the ground while keeping the inner unit and the draining material positioned in the ground.

[0014] Preferably, the method is applicable in an area of claying ground, wet sand or similar being the section of the ground to be drained. Thus, the draining apparatus may be positioned in the ground by being pressed down into the section of the ground.

[0015] The step of providing the draining material to the inner space between the outer surface of the inner part and the inner surface of the outer unit may be performed before the draining apparatus has been positioned in the section of the ground or after the draining apparatus has been positioned in the section of the ground. In any case, the draining material is preferably provided to the inner space before the outer unit is removed from the ground. By providing the draining material to the inner space between the outer surface of the inner part and an inner surface of the outer unit a layer of the draining material is formed along the outer surface of the inner part. The draining material, such as for example gravel, is a material that enables water to flow through the layer of the draining material and further to flow through the plurality of through holes of the inner part to be collected within the inner part.

[0016] The step of removing the outer unit from the ground while keeping the inner unit and the draining material positioned in the ground is performed after the draining apparatus has been positioned in the section of the ground with the draining material being provided to the inner space between the outer surface of the inner part and the inner surface of the outer unit. Thus, the outer unit is removed from the ground after the draining material has been positioned in the ground.

[0017] The step of positioning the draining apparatus in the section of the ground implies that both the inner unit and the outer unit of the draining apparatus are positioned in the section of the ground. Preferably, positioning of the draining apparatus in the ground is performed by simultaneously pressing the outer unit and the inner unit down into the ground. The outer unit is a substantial homogenous unit without through holes. Thus, during positioning of the draining apparatus in the ground, the outer unit prevents a material of the ground to penetrate the though holes of the inner part of the inner unit. Preferably, the inner surface of the outer unit is a smooth surface such as there is low coefficient of friction between the draining material and the inner surface of the outer unit when removing the outer unit from the ground. Preferably, the outer unit is made of metal or of other suitable material.

[0018] Since, the outer unit is removed from the ground while the inner unit and the draining material is kept positioned in the ground, the draining material constitutes a protection layer around the inner part preventing the material of the ground to penetrate the through holes of the inner part. A as result, water may freely flow through the layer of the draining material and further through the plurality of through holes into the inner part to be collected within the inner part. Consequently, an improved method for draining of a section of the ground is provided enabling efficient draining of the section of the ground. Thus, clogging of the inner part may be avoided and typical interruptions for cleaning or reparations may be prevented.

[0019] According to some embodiments the method comprises the step of connecting the outer unit and the inner unit to each other before performing the step of positioning the draining apparatus in the section of the ground. The method further comprises the step of disconnecting the outer unit from the inner unit before performing the step of removing the outer unit from the ground. The outer unit and the inner unit connected to each other may facilitate positioning of the draining apparatus in the section of the ground. Further, the outer unit may be lifted from the ground and may be positioned in, for example, a substantially horizontal position that may facilitate positioning of the inner part within the outer unit before connection to each other.

[0020] According to some embodiments the method comprises the step of pumping out, after the step of removing the outer unit from the ground has been performed, the collected water inside the inner part by means of a pump arrangement comprising a pump configured to pump the collected water from the inner part of the inner unit. Thus, a pumping arrangement may be used to remove water collected in the inner part.

[0021] According to some embodiments the outer unit is an elongated unit and the inner part of the inner unit is an elongated part, wherein the inner part is arranged to be positioned inside the outer unit in parallel with the outer unit. According to the present method, the draining apparatus may be positioned substantially vertically in the section of the ground during performing the step of positioning the draining apparatus in the section of the ground. For the draining apparatus in an intended position for use in the section of the ground having a horizontal surface the vertical direction coincides with a gravity vector at the location of the draining apparatus.

[0022] According to a second aspect, the disclosure relates to a draining apparatus configured to be positioned in a section of the ground and to collect water in the section of the ground, such as in the bottom of a construction pit. The draining apparatus comprises an outer unit arranged to be connected to a machine for at least removal of the outer unit from the ground by the machine and an inner unit comprising an inner part arranged to be positioned within the outer unit and having a plurality of through holes enabling water to flow into the inner part to be collected within the inner part. The draining apparatus comprises a distance arrangement arranged to enable positioning of the inner part in a desired position in relation to the outer unit to create an inner space between an outer surface of the inner part and an inner surface of the outer unit for a draining material to be placed within the inner space. The draining apparatus further comprises a bottom part configured to prevent a material of the ground to enter the inner space during positioning of the draining apparatus in the section of the ground. The outer unit and the inner unit are arranged to enable removal of the outer unit from the ground, after the draining apparatus has been positioned in the section of the ground, while keeping the inner unit and the draining material positioned in the section of the ground to collect water within the inner part.

[0023] The same advantages as have been described above with regards to the first aspect are thereby achieved. Further, since the outer unit is arranged to be connected to a machine for at least removal of the outer unit from the ground by the machine the outer unit may be removed from the ground without need of an action of an operator in a pit or a trench. Thus, at least the process of removal of the outer unit from the ground may be performed automatically by means of the machine. Further, also positioning of the draining apparatus in the ground may be performed by means of the machine acting on the outer unit arranged to cooperate with the inner unit. The detachable connection between the outer unit and the machine facilitates use of the draining apparatus and enables versatile use across different project phases and conditions. Consequently, an improved draining apparatus is provided enabling efficient draining of the section of the ground in a safe manner. Thus, time savings may be achieved and at the same time work-related accidents may be avoided.

[0024] According to some embodiments, the draining material may have function of the distance arrangement and may be used for positioning of the inner part in a desired position inside the outer unit. According to some embodiments the draining apparatus comprises a coupling arrangement arranged for a detachable connection between the outer unit and the inner unit. Thus, the outer unit and the inner unit may be connected to each other which may facilitate the positioning of the draining apparatus in the section of the ground.

[0025] According to some embodiments the bottom part is connected to the inner part and is arranged to abut an edge surface of the outer unit when the inner part has been positioned within the outer unit. The bottom part is arranged such as, during positioning of the draining apparatus in the section of the ground, a force applied on the outer unit is transferred to the bottom part through the edge surface. Thus, the draining apparatus may be positioned in the ground by pressing the outer unit downwards causing the inner unit to be pressed downwards into the ground.

[0026] According to some embodiments the bottom part comprises a positioning portion configured to prevent a relative movement between the outer unit and the inner unit in a direction transverse to a main extension direction of the inner unit. Thus, positioning the draining apparatus in the ground may be yet facilitated and it may be prevented that the draining material provided to the inner space leaves the inner space.

[0027] According to some embodiments the draining apparatus comprises a connecting unit attachable to an attachment part of the outer unit. The connecting unit is arranged to be connected to the machine for connection of the outer unit to the machine. Thus, the outer unit may comprise the attachment part arranged for attachment of the connection unit to the outer unit.

[0028] Preferably, the attachment part is positioned at an upper part of the outer unit to enable positioning of the inner draining apparatus as deep as possible in the ground while the connection unit may be visible for an operator from above of the ground.

[0029] According to some embodiments the distance arrangement is arranged to position the inner part centrally within the outer unit. Thus, positioning of the draining material in the inner space may be facilitated and a layer of the draining material having substantially constant thickness around the inner part of the inner unit may be achieved when the draining material has been provided to the inner space. According to some embodiments, a perforated portion of the inner part with the plurality of through holes has a first length being at least 75% of a second length of the whole inner part. Thus, the collection of water inside the inner part of the inner unit may be improved.

[0030] According to some embodiments at least one of the outer unit and the inner part of the inner unit is a pipe-like unit / part having a diameter. The pipe-like form of the outer unit and / or of the inner part may facilitate the manufacturing of the items and the positioning of the draining apparatus in the ground.

[0031] According to some embodiments the outer unit is an elongated pipe unit and the inner part of the inner unit is an elongated pipe part. Further, the inner part may be arranged to be positioned inside the outer unit in parallel with the outer unit. Thereby, the placement of the draining material in the inner space between the outer surface of the inner unit and the inner surface of the outer unit may be yet improved.

[0032] According to a third aspect, the disclosure relates to a draining system comprising a draining apparatus according to any one of the above-described embodiments and a pump arrangement comprising a pump configured to pump the collected water from the inner unit.

[0033] The same advantages as have been described above with regard to the first aspect are thereby achieved.

[0034] According to some embodiments, the pump of the pump arrangement may be arranged to be positioned inside the inner part of the inner unit or the pump may be placed outside the draining apparatus and water collected in the inner part may be pumped by means of a hose connected to the pump and being positioned in the inner unit.

[0035] According to some embodiments the draining system comprises the draining material to be placed in the inner space between the outer surface of the inner unit and the inner surface of the outer unit. The draining material, such as gravel or lightweight expanded clay aggregate, also called Leca balls or similar, may be chosen depending on the dimensions of the draining apparatus and particularly depending on a distance between the outer surface of the inner unit and the inner surface of the outer unit and depending on the diameter of the through holes of the inner part. Preferably, the size of the stones of the gravel or the size of the Leca balls is greater than the diameter of the through holes of the inner part. Thus, an improved draining system is provided enabling adaptation of the draining system to the requirements of a specific project where draining is needed. For example, when it is beneficial to use a draining apparatus having relatively large dimensions, a relatively large size gravel or Leca balls may be used.

[0036] According to a third aspect, the disclosure relates to a draining apparatus configured to be positioned in the ground, the draining apparatus comprising an outer unit, and an inner unit comprising an inner part having a plurality of through holes enabling water to flow through a wall of the inner part into an inner volume of the inner unit, the inner unit configured to be arranged within the outer unit to thereby form an inner space between an outer surface of the inner part and an inner surface of the outer unit, the inner space configured to receive a draining material, wherein the inner unit comprises a bottom part arranged at a lower end of the inner part, the bottom part configured to close the lower end of the inner space, the bottom part comprising a shoulder portion configured to align with a lower edge surface of the outer unit such that a force applied on the outer unit is transmitted to the bottom part to press the inner unit into the ground, and the outer unit is withdrawable from the ground after the inner space has been filled with the draining material, while the inner unit and the draining material remain in the ground.

[0037] The cooperation between the shoulder portion and the lower edge surface allows a downward force applied on the outer unit to be directly transferred to the inner unit during installation. In practice, the inner unit can therefore be pressed into the ground by means of the outer unit without the need for separate handling tools or direct operator access inside a trench or pit. This simplifies the operation, reduces the number of steps required for installation, and improves site safety by avoiding manual work in unstable ground conditions.

[0038] The bottom part also closes the lower end of the inner space during positioning, thereby preventing soil or fine particles from entering the space before the draining material has been provided. As a result, the annular inner space remains clean and open, which facilitates reliable filling with draining material such as gravel or lightweight aggregate.

[0039] Once the draining material has been placed, the outer unit can be withdrawn while the inner unit and the draining material remain in the ground. The draining material thereby forms a filter pack around the perforated inner part, preventing clogging of the through holes by the surrounding soil. Such an implementation improves the long-term reliability of water collection into the inner volume of the inner unit.

[0040] By integrating the shoulder portion into the bottom part, the apparatus achieves a simplified and robust mechanical interface between the inner unit and the outer unit. No additional coupling devices are required for transmitting force during installation, which reduces manufacturing complexity and increases durability under site conditions. The apparatus can be installed and removed using standard construction machinery acting only on the outer unit, which further enhances operator safety and reduces manual labor.

[0041] Overall, the apparatus provides the same drainage efficiency as previously described embodiments, while focusing on ease of use, robustness, and reliability during installation. The simplified operation due to the shoulder portion of the bottom part ensures that the apparatus can be deployed rapidly and consistently, even in challenging ground conditions such as wet clay or loose sand.

[0042] In line with the present disclosure, the inner unit may comprise a distance arrangement configured to position the inner part in a desired relation to the outer unit so as to maintain the inner space for receiving the draining material. Such a distance arrangement ensures that the perforated inner part is not displaced during installation, even when the apparatus is subjected to uneven ground resistance.

[0043] By holding the inner part in a controlled position relative to the outer unit, the inner space is preserved with a predictable geometry. Such an implementation facilitates reliable provision of draining material around the inner part and avoids the formation of irregular pockets or blocked zones. As a result, water can reach the perforations more evenly, leading to consistent drainage performance and reduced risk of clogging over time.

[0044] Furthermore, in line with the present disclosure, the distance arrangement may comprise a plurality of wings extending from a lid connected to the upper end of the inner part towards the inner surface of the outer unit. The wings create defined contact points with the outer unit, thereby keeping the inner part in its intended position during installation. Such an arrangement integrates the spacing function directly into the lid and avoids the need for separate components or complex fittings, simplifying assembly and reducing the likelihood of misalignment. The wings also provide sufficient mechanical strength to withstand lateral forces when the apparatus is pressed into the ground, ensuring that the annular inner space remains open for filling with draining material.

[0045] Preferably, the lid comprises at least three wings distributed circumferentially. Providing three or more wings ensures stable support of the inner part in multiple directions and prevents tilting or eccentric placement within the outer unit. With circumferential distribution, the annular space between the inner and outer units is maintained with essentially uniform thickness, resulting in a filter pack of draining material that is evenly distributed around the perforated surface of the inner part. A uniform filter pack enhances the hydraulic performance of the apparatus by enabling consistent water inflow from all sides and improves the stability of the inner unit during and after installation.

[0046] By arranging the wings at the lid connected to the upper end of the inner part, the lower perforated region of the inner part remains unobstructed. This allows draining material to enter the annular space freely from above, settling densely along the lower section where water inflow is often greatest. Such a configuration facilitates the formation of a dense and uninterrupted layer of draining material around the perforated surface, thereby reducing the risk of clogging by fine soil particles. Positioning the wings in this upper region also maximizes the effective length of the perforated surface that remains free of obstructions, further improving water collection efficiency.

[0047] As a result, nearly the entire perforated section of the inner part is surrounded by draining material with no interruptions, which improves the available inflow area and optimizes hydraulic performance. At the same time, the wings in the upper region ensure sufficient guidance of the inner part during installation and contribute to maintaining the annular space geometry in the critical phase before the outer unit is withdrawn.

[0048] According to a fourth aspect, the disclosure relates to a method for draining a section of the ground, comprising the steps of positioning a draining apparatus in the ground, the draining apparatus comprising an outer unit and an inner unit according to any one of claims 16 to 24, wherein the inner unit is pressed into the ground by applying a force on the outer unit that is transmitted via a shoulder portion of a bottom part of the inner unit, providing a draining material into an inner space formed between an outer surface of the inner part of the inner unit and an inner surface of the outer unit, and withdrawing the outer unit from the ground after the inner space has been filled with the draining material, while the inner unit and the draining material remain in the ground to collect water inside the inner part.

[0049] According to this aspect, the method provides a structured sequence of steps for installing a draining apparatus in the ground, filling it with draining material, and then withdrawing the outer unit while leaving the functional parts in place. The combination of the outer unit with the inner unit and its bottom part having a shoulder portion ensures that a simple downward force on the outer unit is sufficient to press both units into the ground together. This allows the apparatus to be installed without the need for separate handling or direct access to the inner unit, thereby simplifying the operation and improving work safety. By providing draining material into the inner space defined between the inner unit and the outer unit, the method establishes a filter pack around the perforated inner part before the outer unit is removed. The bottom part simultaneously closes the lower end of the inner space during installation, preventing ingress of soil into the annular gap. As a result, the filter pack can be created in a controlled manner and remains intact once the outer unit is withdrawn. This improves the long-term performance of the drain, as water can pass freely through the draining material and into the perforated inner part without clogging by fine particles from the surrounding ground.

[0050] The withdrawal of the outer unit after the inner space has been filled allows the method to deliver a permanent in-situ drainage structure while using the outer unit only temporarily as an installation aid. This reduces the material required to remain in the ground, simplifies logistics on site, and permits reuse of the outer unit for multiple installations.

[0051] In some embodiments, the method further comprises pumping water out of the inner part of the inner unit after the outer unit has been withdrawn. This allows the drainage structure not only to collect water but also to actively discharge it from the site. The pumping step can be carried out using a pump positioned inside the inner part or by a pump located outside the apparatus connected via a suction hose.

[0052] Preferably, the pump is automatically activated in response to a detected water level inside the inner part. Automatic level-controlled activation reduces the need for operator intervention and ensures continuous drainage even when inflow conditions vary. This increases reliability, prevents overfilling of the inner part, and reduces the risk of delays in excavation or construction work. Automation also improves safety, since personnel do not need to enter the pit or trench to manually start pumping equipment.

[0053] Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

[0054] BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which:

[0056] Fig. 1 schematically illustrates an assembled draining apparatus according to the present disclosure,

[0057] Fig. 2 is a perspective view of the draining apparatus illustrated in Fig. 1 before being assembled, Fig. 3 is a perspective view of the assembled draining apparatus illustrated in Fig. 1 ,

[0058] Fig. 4 schematically illustrates an inner unit of the draining apparatus illustrated in Fig. 1 to Fig. 3,

[0059] Fig. 5 is a flow diagram illustrating a method according to the present disclosure, Fig. 6 schematically illustrates a draining system comprising the draining apparatus illustrated in Fig. 1 to Fig. 3 and a pump arrangement, the draining apparatus is illustrated during positioning in the ground, and

[0060] Fig. 7 schematically illustrates the inner unit and the draining material positioned in the ground after the outer unit of the draining apparatus illustrated in Fig. 1 to Fig. 3 and Fig. 6 has been removed, the pump of the pump arrangement illustrated in Fig. 6 has been positioned in the inner part of the inner unit for pumping the accumulated water from the inner unit.

[0061] DETAILED DESCRIPTION

[0062] Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and / or clarity.

[0063] The terminology used in the description of the embodiments as illustrated in the accompanying drawings is not intended to be limiting of the described method, control arrangement or computer program. Various changes, substitutions and / or alterations may be made, without departing from disclosure embodiments as defined by the appended claims.

[0064] In Fig. 1 , Fig. 2 and Fig. 3 a draining apparatus 1 according to the present disclosure is illustrated. The draining apparatus 1 comprises an outer unit 3 arranged to be connected to a machine 2 for at least removal of the outer unit 3 from the ground by the machine 2. The machine 2, or particularly a part 2 of machine, such as a lifting arm of an excavator, has been schematically illustrated in Fig. 6. The draining apparatus further comprises an inner unit 7 comprising an inner part 7.1 arranged to be positioned within the outer unit 3 and having a plurality of through holes 7.2 enabling water to flow into the inner part 7.1 to be collected within the inner part 7.1. According to the illustrated embodiments, the inner unit 7 comprises a distance arrangement 7.3 arranged to enable positioning of the inner part 7.1 in a desired position in relation to the outer unit 3 to create an inner space 4 between an outer surface 7.4 of the inner part 7.1 and an inner surface 3.2 of the outer unit 3 for a draining material 4.1 to be placed within the inner space 4. The draining material 4.1 has been schematically illustrated in fig. 6. The draining apparatus also comprises a bottom part 7.5 configured to prevent a material of the ground to enter the inner space 4 during positioning of the draining apparatus 1 in the section of the ground. According to the present disclosure, the outer unit 3 and the inner unit 7 are arranged to enable removal of the outer unit 3 from the ground, after the draining apparatus 1 has been positioned in the section of the ground, while keeping the inner unit 7 and the draining material positioned in the section of the ground to collect water within the inner part 7.1.

[0065] The outer unit 3 and the inner unit 7 may be manufactured of metal or of other suitable material.

[0066] The draining apparatus 1 may comprise a coupling arrangement 9 arranged for a detachable connection between the outer unit 3 and the inner unit 7. According to the illustrated embodiments the coupling arrangement 9 comprises a locking stick 9.1 and a locking clamp 9.3. The locking stick 9.1 is arranged to be inserted into and through locking holes 9.2 of the outer unit 3. The inner unit 7 comprises corresponding locking holes 9.2.2 for the locking stick 9.1.

[0067] Preferably, the bottom part 7.5 is connected to the inner part 7.1 and is arranged to abut an edge surface 3.3 of the outer unit 3 when the inner part 7.1 has been positioned within the outer unit 3, wherein, during positioning of the draining apparatus 1 in the section of the ground, a force applied on the outer unit 3 is transferred to the bottom part 7.5 through the edge surface 3.3.

[0068] According to some embodiments, the bottom part comprises a shoulder portion configured to cooperate with the lower edge surface of the outer unit. The shoulder portion provides a defined interface for transferring force from the outer unit to the inner unit during insertion into the ground. By integrating the shoulder portion into the bottom part, the load transfer can be achieved without additional coupling components, thereby simplifying the apparatus and ensuring reliable pressing of the inner unit into the ground.

[0069] The wording bottom relates herein to an intendent position for use of the draining apparatus 1 in relation to the ground when the draining apparatus has been positioned substantially vertically.

[0070] As illustrated in the figures, the outer unit 3 and the inner part 7.1 of the inner unit 7 are pipelike unit / part having diameter d1, d2. Since the inner part 7.1 is arranged to be positioned within the outer unit 3, the diameter d1 of the outer unit 3 is greater than the diameter d2 of the inner part 7.1. Preferably, the bottom part 7.5 has a circular form with a diameter d3. The diameter d3 of the bottom part 7.5 is at least equal to the diameter d1 of the outer part 3. Preferably, the diameter d3 of the bottom part 7.5 is greater than the diameter d1 of the outer part 3. Thus, the force applied on the outer unit 3 may be transferred to the bottom part 7.5. Further, the inner unit 7 and the draining material can be kept positioned in the ground while the outer unit 3 can be removed from the ground. The inner unit 7 and the draining material can be kept positioned in the ground because of friction forces in the ground acting on the bottom part 7.5 of the inner unit 7.

[0071] According to some embodiments the bottom part 7.5 is tapered downwards in a direction for intended use towards the ground. Thus, positioning of the draining apparatus 1 by pressing the draining apparatus 1 into the ground may be facilitated.

[0072] According to some embodiments, the bottom part 7.5 comprises a positioning portion 7.6 configured to prevent a relative movement between the outer unit 3 and the inner unit 7 in a direction x1 transverse to a main extension direction x2 of the inner unit 7. Preferably, the positioning portion 7.6 has a circular form.

[0073] Preferably, the draining apparatus 1 comprises a connecting unit 5 attachable to an attachment part 3.1 of the outer unit 3 and arranged to be connected to the machine 2 for connection of the outer unit 3 to the machine 2. According to the illustrated embodiments, the connecting unit 5 is attached to the attachment part 3.1 by welding. According to some embodiments, the connecting unit 5 may be attached to the attachment part 3.1 by a screw connection arrangement or a bolt connection arrangement or a similar. According to the illustrated embodiments a s-60 attachment has been schematically illustrated as the connecting unit 5. Since the connecting unit 5 is attachable to the attachment part 3.1 , a variety of connecting units adapted to different machines and with different sizes may be used.

[0074] According to some embodiments the distance arrangement 7.3 is arranged to position the inner part 7.1 centrally within the outer unit 3.

[0075] The outer unit 3 may be an elongated pipe unit and the inner part 7.1 of the inner unit 7 may be an elongated pipe part. Preferably, the inner part 7.1 is arranged to be positioned inside the outer unit 3 in parallel with the outer unit 3.

[0076] The outer unit 3 may comprise a funnel portion 3.4 configured to facilitate the placement of the draining material within the inner space 4. As illustrated in the figures, the draining apparatus 1 may comprising a lid 11 configured to be connected to the inner part 7.1 of the inner unit 7 to close the inner part 7.1 from above. Thus, when providing the draining material to the inner space 4 it may be prevented that the draining material falls into the inner unit 7.1.

[0077] Fig. 4 schematically illustrates an inner unit 7 of the draining apparatus 1 illustrated in Fig. 1 to Fig. 3.

[0078] The inner unit 7 comprises an inner part 7.1 arranged to be positioned within the outer unit 3 of the draining apparatus 1. The inner part 7.1 has a plurality of through holes 7.2 enabling water to flow into the inner part 7.1 to be collected within the inner part 7.1.

[0079] The inner part forms a hollow tubular structure defining an inner volume of the inner unit. The through holes provided in the wall of the inner part enable water to pass through the wall into the inner volume, where the collected water may be stored temporarily before being discharged by a pump arrangement. This clarification distinguishes the inner volume from the annular inner space that is configured to receive the draining material.

[0080] Preferably, a perforated portion (7.7) of the inner part (7.1) with the plurality of through holes (7.2) has a first length (11) being at least 75% of a second length (I2) of the whole inner part (7.1). According to the illustrated embodiments the first length 11 is equal the second length I2.

[0081] According to the illustrated embodiments, the inner unit 7 comprises a distance arrangement 7.3 arranged to enable positioning of the inner part 7.1 in a desired position in relation to the outer unit 3 to create an inner space 4 between an outer surface 7.4 of the inner part 7.1 and an inner surface 3.2 of the outer unit 3 for a draining material to be placed within the inner space 4. As illustrated in Fig. 4, the distance arrangement 7.3 may comprise a number of distance units 7.3.1 positioned symmetrically in relation to the inner part 7.1. Thus, the inner part 7.1 may be positioned centrally within the outer unit 3. According to the illustrated embodiments, the distance arrangement 7.3 comprises four distance units 7.3.1. However, other number of distance units 7.3.1 is possible.

[0082] According to some embodiments, the inner unit 7 comprises the bottom part 7.5 connected to the inner part 7.1. The bottom part 7.5 may be arranged to abut an edge surface 3.3 of the outer unit 3 when the inner part 7.1 has been positioned within the outer unit 3, such as during positioning of the draining apparatus 1 in the section of the ground, a force applied on the outer unit 3 is transferred to the bottom part 7.5 through the edge surface 3.3. Fig. 5 is a flow diagram illustrating a method 100 for draining a section of the ground, such as the bottom of a construction pit, according to the present disclosure. The bottom 6 has been illustrated schematically in Fig. 6.

[0083] The method comprises the step of positioning 101 a draining apparatus 1 in the section of the ground. The draining apparatus 1 comprises an outer unit 3 and an inner unit 7 comprising an inner part 7.1 arranged to be positioned within the outer unit 3 and having a plurality of through holes 7.2 enabling water to flow into the inner part 7.1 to be collected within the inner part 7.1 , wherein the inner part 7.1 is positioned within the outer unit 3 to create an inner space 4 between an outer surface 7.4 of the inner part 7.1 and an inner surface 3.2 of the outer unit 3 for a draining material to be placed within the inner space 4. The method 100 further comprises the steps of providing 103 the draining material to the inner space 4 and removing 105 the outer unit 3 from the ground while keeping the inner unit 7 and the draining material positioned in the ground.

[0084] The draining apparatus 1 has been described in detail in conjunction to Fig. 1 to Fig. 4.

[0085] According to some embodiments, the draining apparatus 1 is positioned in the section of the ground by means of a machine. Thus, the method 100 may comprise the step of connecting the draining apparatus 1 to the machine before positioning of the draining apparatus in the section of the ground.

[0086] According to some embodiments the inner part 7.1 may be positioned within the outer part 3 by means of a tool (not shown) configured to position the inner part 7.1 within the outer part 3. After the inner part 7.1 has been positioned within the outer part 3 and after the draining material has been provided to the inner space 4, the tool may be removed.

[0087] According to some embodiments the method may comprise the steps of connecting 107 the outer unit 3 and the inner unit 7 to each other before performing the step of positioning 101 the draining apparatus 1 in the section of the ground and disconnecting 109 the outer unit 3 from the inner unit 7 before performing the step of removing 105 the outer unit 3 from the ground.

[0088] The steps of connecting 107 the outer unit 3 to the inner unit 7 and disconnecting 109 of the outer unit 3 from the inner unit 3 may be performed by an operator or may be done automatically by means of a tool and / or a machine. Further, the method 100 may comprise the step of pumping out 111 , after the step of removing 105 the outer unit 3 from the ground has been performed, the collected water inside the inner part 7.1 of the inner unit 7 by means of a pump arrangement 12 comprising a pump 14 configured to pump the collected water from the inner unit 7.

[0089] Preferably, the outer unit 3 is an elongated unit and the inner part 7.1 of the inner unit 7 is an elongated part, wherein the inner part 7.1 is arranged to be positioned inside the outer unit 3 in parallel with the outer unit, wherein during performing the step of positioning 101 the draining apparatus 1 in the section of the ground, the draining apparatus 1 is positioned substantially vertically in the section of the ground.

[0090] Fig. 6 schematically illustrates a draining system 10 comprising the draining apparatus 1 illustrated in Fig. 1 to Fig. 3. The draining system 10 comprises a draining apparatus 1 and a pump arrangement 12 comprising a pump 14 configured to pump the collected water from the inner part 7.1 of the inner unit 7. According to the illustrated embodiments, the pump 14 has been positioned inside the inner part 7.1 of the inner unit 7, wherein the pump is connected to a hose 15 for pumping out water collected in the inner part 7.1. According to some embodiments, a pump may be placed outside the draining apparatus 1 and water collected in the inner part may be pumped by means of a hose connected to the pump and being positioned in the inner unit 7.1.

[0091] In Fig, 6 the draining apparatus 1 is illustrated being partly positioned in a section of the ground, such as a bottom 6 of a construction pit. According to the illustrated embodiments, the draining apparatus 1 has been positioned in the ground by means of a machine 2 connected to the outer unit 3 via a connecting unit 5 attachable to an attachment part 3.1 of the outer unit 3. During positioning of the draining apparatus 1 the machine 2 acts on the outer unit 3 in a direction a1. Preferably, the direction a1 is a substantially vertical direction downwards towards the ground. As illustrated in Fig. 7, after the draining apparatus 1 has been positioned in the ground, the outer unit 3 is removed from the ground while the inner unit 7 and the draining material 4.1 is kept positioned in the ground. During removing of the outer unit 3 from the ground the machine 2 acts on the outer unit 3 in a further direction a2. Preferably, the further direction a2 is a substantially vertical direction upwards from the ground.

[0092] Optionally, the system may comprise the draining material 4.1 to be placed in the inner space 4 between the outer surface 7.4 of the inner unit 7 and the inner surface 3.2 of the outer unit 3. The draining material 4.1 has been illustrated schematically in Fig. 6. The draining material may be gravel or lightweight expanded clay aggregate, also called Leca balls or a similar material. Preferably, the size of the stones of the gravel or the size of the Leca balls is greater than the diameter of the through holes 7.2 of the inner part 7.1. The size of gravel or of Leca balls is usually specified in millimeters. Where the grains are non- spherical, the size may indicate the largest extension of the grains. Preferably, the size of the stones of the gravel or the size of the Leca balls is at least 8 mm. Preferably, the size of the gravel stones or the size of the Leca balls is no more than 60 mm. The size of the stones of the gravel or the size of the Leca balls may sometimes be called the grain size. Gravel is usually categorized in different categories, decided by so called fractions. According to the present disclosure the fraction of gravel may be, for example 8-16. Preferably, the diameter of the through holes 7.2 of the inner part 7.1 is no more than 20 mm.

[0093] Fig. 7 schematically illustrates a cross section of the inner unit 7 positioned in the ground after the outer unit 3 of the draining apparatus 1 illustrated in Fig. 1 to Fig. 3 and Fig. 6 has been removed from the ground. As illustrated in Fig. 7, the inner unit 7 and the draining material 4.1 are kept remaining in the ground after the outer unit 3 has been removed by means of the machine 2. According to the illustrated embodiments, the pump 14 of the pump arrangement 12 has been positioned inside the inner part 7.1 of the inner unit 7 for pumping the accumulated water from the inner part 7.1. Preferably, the pump 14 is positioned at the bottom of the inner part 7.1. According to some embodiments, the pump 14 may be positioned outside the inner part 7.1 above the ground 6 and the hose 15 may be positioned inside the inner part 7.1.

[0094] According to some embodiments, the pump arrangement may further comprise a control unit configured to activate the pump automatically in response to a detected water level inside the inner part. A level sensor may be positioned inside the inner volume of the inner part, and when the water level exceeds a threshold, the control unit starts the pump to discharge the collected water. Such automation ensures reliable operation without continuous manual supervision and reduces the need for personnel to enter the excavation area.

Claims

CLAIMS1. A method (100) for draining a section of the ground, such as the bottom of a construction pit, the method comprising the steps of: positioning (101) a draining apparatus (1) in the section of the ground, wherein the draining apparatus (1) comprises: an outer unit (3), and an inner unit (7) comprising an inner part (7.1) arranged to be positioned within the outer unit (3) and having a plurality of through holes (7.2) enabling water to flow into the inner part (7.1) to be collected within the inner part (7.1), wherein the inner part (7.1) is positioned within the outer unit (3) to create an inner space (4) between an outer surface (7.4) of the inner part (7.1) and an inner surface (3.2) of the outer unit (3) for a draining material to be placed within the inner space (4), providing (103) the draining material to the inner space (4), and removing (105) the outer unit (3) from the ground while keeping the inner unit (7) and the draining material positioned in the ground.

2. The method (100) according to claim 1, further comprising the step of: connecting (107) the outer unit (3) and the inner unit (7) to each other before performing the step of positioning (101) the draining apparatus (1) in the section of the ground, and disconnecting (109) the outer unit (3) from the inner unit (7) before performing the step of removing (105) the outer unit (3) from the ground.

3. The method (100) according to claim 1 or 2, further comprising the step of: pumping out (111), after the step of removing (105) the outer unit (3) from the ground has been performed, the collected water inside the inner part (7.1) of the inner unit (7) by means of a pump arrangement (12) comprising a pump (14) configured to pump the collected water from the inner unit (7).

4. The method (100) according to any one of the preceding claims, wherein the outer unit (3) is an elongated unit and the inner part (7.1) of the inner unit (7) is an elongated part, wherein the inner part (7.1) is arranged to be positioned inside the outer unit (3) in parallel with the outer unit, wherein during performing the step of positioning (101) the draining apparatus (1) in the section of the ground, the draining apparatus (1) is positioned substantially vertically in the section of the ground.

5. A draining apparatus (1) configured to be positioned in a section of the ground and to collect water in the section of the ground, such as in the bottom of a construction pit, wherein the draining apparatus (1) comprises: an outer unit (3) arranged to be connected to a machine (2) for at least removal of the outer unit (3) from the ground by the machine (2), an inner unit (7) comprising an inner part (7.1) arranged to be positioned within the outer unit (3) and having a plurality of through holes (7.2) enabling water to flow into the inner part (7.1) to be collected within the inner part (7.1), wherein the draining apparatus comprises a distance arrangement (7.3) arranged to enable positioning of the inner part (7.1) in a desired position in relation to the outer unit (3) to create an inner space (4) between an outer surface (7.4) of the inner part (7.1) and an inner surface (3.2) of the outer unit (3) for a draining material (4.1) to be placed within the inner space (4), and a bottom part (7.5) configured to prevent a material of the ground to enter the inner space (4) during positioning of the draining apparatus (1) in the section of the ground, wherein the outer unit (3) and the inner unit (7) are arranged to enable removal of the outer unit (3) from the ground, after the draining apparatus (1) has been positioned in the section of the ground, while keeping the inner unit (7) and the draining material positioned in the section of the ground to collect water within the inner part (7.1).

6. The draining apparatus (1) according to claim 5 comprising a coupling arrangement (9) arranged for a detachable connection between the outer unit (3) and the inner unit (7).

7. The draining apparatus (1) according to claim 5 or 6, wherein the bottom part (7.5) is connected to the inner part (7.1) and is arranged to abut an edge surface (3.3) of the outer unit (3) when the inner part (7.1) has been positioned within the outer unit (3), wherein, during positioning of the draining apparatus (1) in the section of the ground, a force applied on the outer unit (3) is transferred to the bottom part (7.5) through the edge surface (3.3).

8. The draining apparatus (1) according to any one of claims 5 to 7, wherein the bottom part (7.5) comprises a positioning portion (7.6) configured to prevent a relative movement between the outer unit (3) and the inner unit (7) in a direction (x1) transverse to a main extension direction (x2) of the inner unit (7).

9. The draining apparatus (1) according to any one of claims 5 to 8 comprising a connecting unit (5) attachable to an attachment part (3.1) of the outer unit (3) and arranged to be connected to the machine (2) for connection of the outer unit (3) to the machine (2).

10. The draining apparatus (1) according to any one of claims 5 to 9, wherein the distance arrangement (7.3) is arranged to position the inner part (7.1) centrally within the outer unit (3).

11. The draining apparatus (1) according to any one of claims 5 to 10, wherein a perforated portion (7.7) of the inner part (7.1) with the plurality of through holes (7.2) has a first length (11) being at least 75% of a second length (I2) of the whole inner part (7.1).

12. The draining apparatus (1) according to any one of claims 5 to 11, wherein at least one of the outer unit (3) and the inner part (7.1) of the inner unit (7) is a pipe-like unit / part having a diameter (d1, d2).

13. The draining apparatus (1) according to claim 12, wherein the outer unit (3) is an elongated pipe unit and the inner part (7.1) of the inner unit (7) is an elongated pipe part, wherein the inner part (7.1) is arranged to be positioned inside the outer unit (3) in parallel with the outer unit (3).

14. A draining system (10), comprising: a draining apparatus (1) according to any one of claims 5 to 13, and a pump arrangement (12) comprising a pump (14) configured to pump the collected water from the inner part (7.1 of the inner unit (3).

15. The draining system (10) according to claim 14, further comprising the draining material (4.1) to be placed in the inner space (4) between the outer surface (7.4) of the inner unit (7) and the inner surface (3.2) of the outer unit (3).

16. A draining apparatus (1) configured to be positioned in the ground, the draining apparatus (1) comprising: an outer unit (3), and an inner unit (7) comprising an inner part (7.1) having a plurality of through holes (7.2) enabling water to flow through a wall of the inner part (7.1) into an inner volume of the inner unit (7), the inner unit (7) configured to be arranged within the outer unit (3) to thereby form an inner space (4) between an outer surface (7.4) of the inner part (7.1) and an inner surface (3.2) of the outer unit (3), the inner space (4) configured to receive a draining material (4.1), wherein:the inner unit (7) comprises a bottom part (7.5) arranged at a lower end of the inner part (7.1), the bottom part (7.5) configured to close the lower end of the inner space (4), the bottom part (7.5) comprising a shoulder portion configured to align with a lower edge surface (3.3) of the outer unit (3) such that a force applied on the outer unit (3) is transmitted to the bottom part (7.5) to press the inner unit (7) into the ground, and the outer unit (3) is withdrawable from the ground after the inner space (4) has been filled with the draining material (4.1), while the inner unit (7) and the draining material (4.1) remain in the ground.

17. The draining apparatus (1) according to claim 16, wherein the inner unit (7) comprises a distance arrangement (7.3) configured to position the inner part (7.1) in a desired position in relation to the outer unit (3) so as to maintain the inner space (4) for receiving the draining material (4.1).

18. The draining apparatus (1) according to claim 17, wherein the distance arrangement (7.3) comprises a plurality of wings extending from a lid (11) configured to be connected to the inner part (7.1) towards the inner surface (3.2) of the outer unit (3).

19. The draining apparatus (1) according to claim 18, wherein the lid (11) comprises at least three wings distributed circumferentially around the lid (11).

20. The draining apparatus (1) according to any one of claims 16 to 19, wherein the bottom part (7.5) has a diameter at least equal to an inner diameter of the outer unit (3).

21. The draining apparatus (1) according to any one of claims 16 to 20, wherein the bottom part (7.5) has a downwardly tapered portion.

22. The draining apparatus (1) according to any one of claims 16 to 21, wherein the outer unit (3) has an inner surface (3.2) selected to reduce friction against the draining material (4.1) during withdrawal of the outer unit (3).

23. The draining apparatus (1) according to any one of claims 16 to 22, wherein the outer unit (3) comprises a funnel portion (3.4) at an upper end configured to facilitate filling of the inner space (4) with the draining material (4.1).

24. The draining apparatus (1) according to any one of claims 16 to 23, wherein a perforated portion (7.7) of the inner part (7.1) provided with the through holes (7.2) extends over at least 75% of a length of the inner part (7.1).

25. A draining system (10), comprising: a draining apparatus (1) according to any one of claims 16 to 24, and a pump arrangement (12) comprising a pump (14) configured to pump water collected from the inner part (7.1) of the inner unit (7).

26. The draining system (10) according to claim 25, further comprising the draining material (4.1) to be placed in the inner space (4) between the outer surface (7.4) of the inner part (7.1) and the inner surface (3.2) of the outer unit (3).

27. A method for draining a section of the ground, comprising the steps of: positioning a draining apparatus (1) in the ground, the draining apparatus (1) comprising an outer unit (3) and an inner unit (7) according to any one of claims 16 to 24, wherein the inner unit (7) is pressed into the ground by applying a force on the outer unit (3) that is transmitted via a shoulder portion of a bottom part (7.5) of the inner unit (7), providing a draining material (4.1) into an inner space (4) formed between an outer surface (7.4) of the inner part (7.1) of the inner unit (7) and an inner surface (3.2) of the outer unit (3), and withdrawing the outer unit (3) from the ground after the inner space (4) has been filled with the draining material (4.1), while the inner unit (7) and the draining material (4.1) remain in the ground to collect water inside the inner part (7.1).

28. The method according to claim 27, further comprising activating a pump arrangement (12) to pump water collected inside the inner part (7.1) of the inner unit (7).

29. The method according to claim 28, wherein the pump arrangement (12) is positioned inside the inner part (7.1).

30. The method according to claim 28 or 29, wherein the pump arrangement (12) is activated automatically in response to a water level detected inside the inner part (7.1).

31. The method according to any one of claims 27 to 30, wherein the draining material (4.1) provided to the inner space (4) comprises gravel or lightweight expanded clay aggregate.

32. The method according to any one of claims 27 to 31 , wherein the draining apparatus (1) is positioned substantially vertically in the ground.

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