Flushing head for slurry wall grabber

Abstract

Flushing head (S) for cleaning slotted wall connections, comprising a) at least one media chamber (M) for receiving and conveying a rinsing medium (L), wherein the media chamber (M) has at least one outlet nozzle (A1, A2...) through which the rinsing medium (L) can exit the media chamber (M) under high pressure into the environment adjacent to the media chamber, b) at least one media connection (T) at the media chamber (M) for feeding the flushing medium (L) into the media chamber (M), c) a connecting section (V) for attaching the media chamber (M) to a diaphragm wall grab (G), wherein the flushing head (S) is designed to be attached to a diaphragm wall grab (G) and lowered with it into an existing or to be created slot (D) in the ground, so that during this time the flushing medium (L) can exit from the at least one outlet nozzle (A1, A2) and be directed against a surface to be cleaned, which delimits the slot, in order to loosen any adhesions or contaminants there.

Description

[0001] The present invention relates to a flushing head for slurry wall grippers used to produce slurry walls.

[0002] A diaphragm wall is created by excavating trenches in sections using a diaphragm wall grab or a trench cutter, and then backfilling them with a hardening compound. The trenches (several meters long, several meters deep, but only about 0.5 to 1.8 meters wide) are stabilized during excavation with a liquid support fluid such as bentonite to prevent soil collapse. Once the final depth is reached, reinforcement cages are typically placed in the trench, and then hardening concrete is poured in using a slurry method. For this reason, they are also called cast-in-place diaphragm walls. By joining these individual elements (also called "panels") end-to-end, continuous, stable, and generally watertight walls are created. The individual panels meet at joints.

[0003] Generally, diaphragm walls are classified as either one-phase or two-phase. In one-phase diaphragm walls, the trenches are excavated using a support fluid containing a hardening component. This fluid remains in the trench after excavation and hardens on its own; these are also known as cut-off walls. The primary function of cut-off walls is to seal them, preventing water from passing through them. Structural integrity is of secondary importance.

[0004] In contrast, with two-phase diaphragm walls, as described above, the excavation is first carried out using a support fluid (bentonite), which is then replaced with a hardening medium (concrete). The process thus comprises two phases. Such a cast-in-place concrete diaphragm wall fulfills not only a sealing function but also structural requirements. A typical application for a cast-in-place concrete diaphragm wall is the enclosure of an excavation pit.

[0005] The general term "diaphragm wall" therefore terminologically encompasses cast-in-place concrete diaphragm walls and cut-off walls and will be used as such in the following.

[0006] To create a stable and watertight diaphragm wall, it is essential that each individual lamella is securely and tightly connected to the adjacent lamellae at its end face. Joint sheets or flat joints are frequently used for this purpose, forming or covering the end face of the diaphragm during the concreting process.

[0007] A joint strip positioned over a defined height on the end face of the slot, for example, remains in the ground after curing and, with its outer surface facing away from the finished lamella, forms the connection surface or joint for the next lamella. A flat joint, on the other hand, is drawn after curing, so that the remaining, preferably profiled, end face of the finished lamella itself directly forms the connection surface or joint for the next lamella. In both cases, however, the problem frequently arises that a finished lamella is contaminated on its end face by surrounding concrete, bentonite residue, or other adhering substances and therefore, for example, has an inhomogeneous surface with varying adhesion properties for concrete, which makes a tight and stable connection of another lamella difficult.This can, for example, lead to groundwater seeping through the joint between two panels of a diaphragm wall, contrary to its originally intended function. Subsequent sealing is associated with considerable additional costs and delays in construction progress. The stability of the diaphragm wall is also compromised if the individual panels fail to form a mechanical bond with each other due to adhering substances and contaminants.

[0008] A similar problem arises when connecting a diaphragm wall to an existing wall, typically running perpendicular to the diaphragm wall (existing wall), which may be a cast-in-place concrete diaphragm wall. After excavating the trench adjacent to the existing wall, the stabilizing slurry can form filter cake-like deposits in the area of ​​the planned connection joint. Such undesirable adhesions or other contaminants, which could compromise the tight connection of the diaphragm wall to the existing wall, must be avoided. This effect is particularly pronounced in granular, coarse-grained soils and rock strata. In these cases, significant overprofile and bulges can occur, which are then filled with concrete after pouring. This can significantly impair and hinder cleaning of the wall using grab buckets, greatly increasing the risk of residues and adhesions.

[0009] The object of the invention was therefore to offer a device for overcoming the aforementioned disadvantages. This object is achieved by a flushing head with the features of claim 1 or a slotted wall gripper connected to the flushing head according to claim 5. Further advantageous embodiments are described in the dependent claims.

[0010] The invention is based on the finding that a hydraulically tight and mechanically sufficiently stable connection between two adjacent diaphragm wall elements or lamellae, or between a lamella and a wall running transversely to it, can be ensured by first cleaning the joint of a completed first lamella before the adjacent slot for the construction of the adjacent second lamella is filled with concrete. The aim of the cleaning is to remove the dirt and adhering substances to such an extent that the concrete of the second lamella connects sufficiently tightly, securely, and without interruption to the cleaned end face of the first lamella in order to establish a mechanically and hydraulically stable connection.

[0011] The implementation of this project appears to fail at first glance due to the fact that the slot adjacent to the front face of the first lamella is already filled with stabilizing bentonite suspension during excavation, which significantly hinders direct access to the front face and thus its cleaning. However, this problem can be solved in an inventive manner using the rinsing head according to the invention, as described below.

[0012] According to one embodiment of the invention, the cleaning head comprises at least one media chamber for receiving and conveying a cleaning medium. The media chamber is designed to allow the cleaning medium, introduced into the chamber via a media connection, to flow or spray out into the external environment of the media chamber under sufficiently high pressure (e.g., 0–20 bar) through at least one, preferably several, outlet nozzles, each in the form of a cleaning jet. Advantageously, the cleaning head is positioned so close to the end wall to be cleaned that the outflowing medium loosens deposits or contaminants on the end wall and prepares it for the stable and tight connection of the adjacent lamella to be subsequently created.

[0013] According to the invention, the flushing head also includes a connecting section suitable for attaching the flushing head to a slot wall grab. This feature implements a further aspect of the invention, bringing the cleaning of the end wall into inventive interaction with the excavation of the slot adjacent to the existing lamella, which is necessary anyway.

[0014] For this purpose, the flushing head according to the invention is attached to the diaphragm wall grab, preferably slightly above the grab buckets that collect the soil. Preferably, but not necessarily, the elongated media chamber extends horizontally and parallel to the end wall of a first lamella to be cleaned, at the smallest possible distance therefrom. The cleaning ("polishing") of the end wall of this first lamella can then be carried out particularly advantageously using the existing diaphragm wall grab, either during or after the excavation of the next trench adjacent to the end wall to form the next lamella.

[0015] The excavation process—as described above—is carried out using a diaphragm wall grab, which, through repeated lowering, scooping up soil, lifting it out, and disposing of the soil laterally, gradually excavates the trench to the desired depth. The flushing head attached to the diaphragm wall grab follows this up-and-down movement, thus sliding up and down along the end face of the already completed adjacent lamella to be cleaned. By simultaneously supplying the media chamber with the flushing medium (for example, via a hose or pipe that can be lowered together with the diaphragm wall grab), the medium is directed against the end face in the form of one or more cleaning jets emerging from the media chamber, thus subjecting the end face to the desired cleaning process during the up-and-down movement of the grab.

[0016] This cleaning can take place while the diaphragm wall grab continues to work its way deeper. However, it is technically preferable, either additionally or alternatively, to carry out the cleaning process only after the excavation is completely finished, by moving the diaphragm wall grab up and down without moving any soil, and solely for the purpose of cleaning the face wall. It is also conceivable to attach the flushing head to the diaphragm wall grab only when the trench has been completely excavated and is ready to be cleaned.

[0017] The cleaning medium used can be chosen by a person skilled in the art. Preferably, it is a medium containing water and / or air. It is also conceivable to add abrasive additives to the cleaning medium to increase its cleaning effect. Furthermore, the media chamber can be equipped with multiple media connections to selectively provide, mix, or generate different cleaning media at different times or for different purposes within the media chamber.

[0018] Since the trench to be excavated is filled with bentonite suspension for stabilization, the trench wall grab, along with the flushing head according to the invention, immerses itself in the suspension during lowering. The flushing medium and the pressure prevailing in the media chamber must therefore be selected such that, despite the hydrostatic back pressure of the bentonite suspension, the flushing medium exits the outlet nozzles of the media chamber with sufficient momentum for the desired cleaning.

[0019] According to an advantageous embodiment of the invention, at least one outlet nozzle of the cleaning head is adjustable in order to, for example, adjust the flow cross-section or the outflow direction relative to the media chamber. This makes it possible, for example, to direct the respective cleaning jet specifically to areas of the end wall that may be particularly susceptible to soiling. Different flow cross-sections at different outlet nozzles allow for an optimal distribution of the total volume flow to the individual nozzles or the areas of the end wall they act upon.

[0020] According to an advantageous embodiment of the invention, the media chamber is formed entirely or partially cylindrically. This design is particularly pressure-resistant and allows the use of standard components for manufacturing the cleaning head. Furthermore, this design allows for the arrangement of several outlet nozzles offset around the circumference of the media chamber, resulting in cleaning jets in different directions even without specially adjustable outlet nozzles.

[0021] Preferably, the media chamber extends with its (cylindrical) axis in a horizontal orientation over a width approximately equal to the width Y. Dof the slot to be excavated or the gripper shells of the diaphragm wall gripper. Advantageously, the outlet nozzles of the media chamber are also distributed over at least 50%, preferably at least 80% or even more of this width, so that cleaning jets can exit the media chamber well distributed across the width and be directed onto the adjacent end face of the already completed lamella.

[0022] Advantageously, a diaphragm wall grab can also be equipped with several flushing heads according to the invention. For example, a flushing head could be arranged on each side of the frame of a diaphragm wall grab in order to direct the flushing medium against one or the other boundary surface of the diaphragm opposite it in the longitudinal direction X, as required. This eliminates the need to reconfigure the diaphragm wall grab or rotate it by 180°.

[0023] In principle, it is also conceivable to arrange the washing head according to the invention in a longitudinal direction X on a slot wall gripper in order to be able to clean a side wall of a slot existing between two end-face boundary surfaces.

[0024] The end wall of a completed lamella, as described above, can be assumed to be a largely flat surface. However, it is also preferable for the end wall to be profiled in order to form a positive-locking connection with the next lamella to be attached, thereby further improving the sealing and mechanical stability (an example shows Fig. 3 or Fig. 5, see below). The profiling can – as already described in the introduction – also be formed by separate elements that are arranged for this purpose in the area of ​​the end wall during the production of the lamella. For example, joint plates can be provided that are positioned between two adjacent lamellae and remain there, with the outer side of the joint plate facing away from the finished lamella then forming the end face to be cleaned according to the invention. However, the use of so-called flat joints is also conceivable, which also initially limit the slot on the end wall side. After the lamella has hardened and the adjacent slot has been excavated, the flat joint is drawn, and the cleaning according to the invention then takes place directly on the (concrete) end face of the previously produced lamella, against which concrete is subsequently poured.

[0025] The function of the rinsing head according to the invention is not limited by the use of joint sheets or flat joints, since the cleaning is equally effective for both joint sheets and the immediate lamella end face or joint.

[0026] Instead of the aforementioned end wall, the flushing head according to the invention can, of course, also be used to prepare the connection of a lamella yet to be constructed to an existing transverse wall (existing wall) running orthogonally or, if necessary, obliquely to this lamella, for example, to create a cutoff wall or block placed in front of an excavation. A cutoff block is understood to be several cutoff wall lamellae arranged in a row and overlapping, which together form a sealed body ("block") made of cutoff material. Such cutoff blocks are usually arranged outside of excavations with tunnel passages and abut tightly against the excavation walls. This cutoff block is later passed through by the tunnel boring machine before entering the excavation, thus preventing any potential groundwater ingress into it.

[0027] This case was also briefly described in the introduction. An example of this is shown. Fig. 4 (su). In the connection area or joint between the lamella to be created and the transverse finished wall, a joint sheet / flat joint is generally not provided; instead, the wall is usually relatively smooth. However, the existing slurry can lead to the deposition of contaminants and filter cake there. For a satisfactory seal between the lamella and the existing wall (especially cast-in-place concrete diaphragm walls), cleaning according to the invention must also be carried out here before the lamella is created. The cleaning of the transverse wall using a flushing head is then carried out analogously to the aforementioned method, precisely at the point on the transverse wall or future joint where the lamella to be created is to connect. Liquid sealing wall compound can also be used as the flushing medium here.

[0028] Furthermore, it is also conceivable to connect a diaphragm wall to an existing bored pile wall or other retaining walls, which can be cleaned using the invention.

[0029] An embodiment of the invention will now be explained in more detail with reference to illustrative figures. For this purpose, it will be shown that... Fig. 1 a rinsing head according to the invention in perspective view; Fig. 2 a slot wall grabber with flushing head; Fig. 3 a slot wall grab with flushing head in use; Fig. 4 the connection of a lamella to an existing, transverse diaphragm wall, and Fig. 5. the connection of a lamella to an existing lamella.

[0030] Fig. Figure 1 shows a schematic oblique view of a flushing head S according to the invention. The flushing head S comprises a closed media chamber M with a cylindrical shape, which extends with its axis in a transverse direction Y. The longitudinal extent of the media chamber M corresponds approximately to the width Y. D of a slot D for a diaphragm wall element (see Fig. 4 and Fig. 5) The media chamber M has a media connection T, through which the chamber can be supplied with a rinsing medium L under a predeterminable pressure.

[0031] A plurality of outlet nozzles A1, A2... are distributed in the transverse direction Y and in a circumferential direction over the outer surface of the media chamber, so that the rinsing medium can escape through the outlet nozzles to one side into the environment of the media chamber.

[0032] A cuboid connecting section V is firmly attached to the media chamber, preferably welded. The connecting section V in turn serves to attach the media chamber to a Fig. 1. The diaphragm wall gripper G (not shown). Preferably, the connecting section V can be screwed to a section prepared for this purpose on the diaphragm wall gripper G or otherwise detachably connected. In principle, differently shaped fastening elements are also conceivable for attaching the gripper to the connecting section V shown. Further, unspecified lifting elements serve to handle the flushing head with lifting tools.

[0033] In Fig. Figure 2 shows a schematic side view of a diaphragm wall grab G. It essentially consists of a frame extending primarily in a vertical direction Z and a longitudinal direction X perpendicular to it, and two grab buckets (in the closed position) located at the lower end of the frame, which serve as gripping elements. The grab buckets are designed to scoop up soil when the grab G is lowered into a trench, after which the grab can be pulled upwards and the scooped soil discharged laterally. This creates a shaft or trench D with a width Y measured in the transverse direction Y (perpendicular to the plane of the drawing). D . (see Fig. 4) The extent X D of the slot in longitudinal direction X (orthogonal to the lateral direction Y and in Fig. 2 horizontally from right to left) corresponds at least to the extent of the open gripper jaws; depending on requirements, the slot can also be made significantly longer. The depth Z D The length of the resulting slit D can range from a few meters to over 100 m.

[0034] A flushing head S according to the invention is arranged on the frame, its longitudinal axis extending in the transverse direction Y (orthogonal to the plane of the drawing) in this illustration. The connecting section V, hidden in this illustration, is screwed to the frame so that the flushing head S forms a rigid assembly with the frame. Also visible is the media connection T projecting from an upper surface of the media chamber M, as well as several outlet nozzles A1, A2..., which are directed away from the frame of the gripper G (in the illustrated case to the left, upper left, and lower left). The gripper can be moved up and down together with the flushing head in the vertical direction Z, for example, while a slot D for a diaphragm wall element (lamella) is excavated with the gripper.

[0035] Fig. Figure 3 shows a diaphragm wall grab G with a flushing head S according to the invention in operation. The grab slides, starting from a ground surface (GOK), in a slot D of length X.D downwards, to excavate the trench to the desired depth. Meanwhile, the trench is filled to ground level with a bentonite suspension as a support fluid to prevent soil collapse into the trench. Adjacent to trench D on both sides are two already completed diaphragm wall panels, F1 and F2. The diaphragm wall element to be constructed in trench D will complete the diaphragm wall.

[0036] At the in Fig. On the left side of slot D, it borders the already completed diaphragm wall element F1 (lamella). A vertical end face H1 of this lamella F1, with a temporarily inserted flat joint P1, extends in the vertical direction Z and in the transverse direction Y, thus forming a boundary surface for the adjacent slot D. Similarly, the second end face H2 opposite in slot D is temporarily covered by a second flat joint P2. On the side of the frame facing the end face H1, a flushing head S according to the invention is arranged on the diaphragm wall gripper G, with the outlet nozzles A1, A2... directed at different angles towards the end face H1, as indicated by arrows.

[0037] After the complete excavation of the slurry-filled slot D, the left flat joint P1 is first drawn, exposing the profiled connection surface or end face of the already constructed, hardened left lamella. The opposite right flat joint P2 is also drawn, so that the two already completed lamellae F1 and F2 frame the slot D on the right and left with their respective exposed concrete end faces H1 and H2. The slot D is then to be filled with concrete using the slurry method, displacing the bentonite slurry. The aim is to achieve the tightest and most stable possible connection between the resulting new lamella and the end faces H1 and H2 of the existing lamellae F1 and F2.

[0038] Before concreting, the media chamber M of the flushing head S is pressurized with flushing medium by a surface pump under sufficiently high pressure, while the diaphragm wall grab G is moved upwards and / or downwards along the end wall H1. This can be done while the trench is being excavated or after this has already been completed. The cleaning jets of flushing medium exiting the nozzles strike the end wall H1 with sufficient momentum, removing deposits and contaminants that could otherwise compromise the tight and stable connection of the new lamella to the existing lamella F1. By rotating the grab G by 180°, the other end wall H2 can also be cleaned accordingly.

[0039] The Fig. 4 and Fig. Figure 5 shows a schematic top view of the connection of a newly constructed lamella to a transversely running, completed diaphragm wall W ( Fig. 4), or to the end face of an existing diaphragm wall element ( Fig. 5).

[0040] The diagram shows how, within a dug-out slot D with a width Y, D and the length X D The flushing medium L is directed from the flushing head S, which is schematically shown on the diaphragm wall grab G, onto the connection surface H to be cleaned, before the diaphragm wall grab G is lifted out of the slot and the slot is filled with concrete.

[0041] In the variant according to Fig. 4. Adhesions, e.g. in the form of filter cake Q or other contaminants, can be seen on the transverse diaphragm wall W, which can be removed with the flushing head S according to the invention or a cleaning carried out with it before concreting.

[0042] In the Fig.In the case shown in point 5, a flat joint P (indicated there) was first introduced on the front face H, which was then drawn before the slot was filled. The front face H can be cleaned before concreting using the flushing head S. Reference symbol list A1, A2... Outlet nozzle D Slot for creating a lamella F F, F1, F2 diaphragm wall element (lamella) G diaphragm wall grab H, H1, H2 End wall, end face or interface of a lamella F L Flushing medium M Media Chamber P1, P2 joint sheet or flat joint Q Filter cake / Impurities S flush head T Media connection V Connection section Existing diaphragm wall X Longitudinal direction X D Length of the slot D Y transverse direction Y D Width of the gripping element of a diaphragm wall gripper and of the slot D Z Altitude direction Z D Slot depth D

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