METHOD FOR EXTRACT CONTROL DURING DRILLING IN THE GROUND AND DRILLING EQUIPMENT

Description

[0001] The invention relates to a method for controlling overburden during tunneling in the ground and to a tunneling device suitable for carrying out the method.

[0002] The underground installation of pipes using pipe jacking has been a proven civil engineering technique for many decades. Thanks to advances, particularly in the past 30 years, tunnels up to 1,000 meters in length and with diameters of up to almost 5 meters are now successfully completed. The tunneling techniques differ primarily in the type of excavation of soil or rock at the so-called tunnel face. The excavated material, referred to below as overburden, can be transported from the tunnel face to the launch shaft in various ways, e.g., in conveyor buckets, via screw conveyors, or even flushing with water.

[0003] With all methods, it is important to match the advance rate with the amount of excavated material. Excessive excavation of excavated material is often problematic, particularly when excavating in unstable soils below groundwater. If the volume of excavated material in the ground exceeds the volume of the device introduced into the ground using the method, depending on the extent of the excess excavation, this can lead to subsidence and even major surface collapses, which can cause significant damage to surface structures, roads, and any existing underground infrastructure. Depending on the overlying soils and the depth of the tunnel, this damage often only becomes apparent after a considerable time delay.

[0004] It is known to control the volume of removed overburden. However, this does not achieve the accuracy required to reliably prevent the undesirable consequences of excessive overburden removal. Known methods include determining the quantity and density of the extracted overburden. With hydraulic extraction, volume control is also complex because a separation system is required to separate the overburden from the conveyed fluid. It is also known to use belt scales or simply measure the volume of the extracted overburden. In addition to the associated measurement inaccuracies, all methods also have the error of virtually impossible precise in-situ determination of the bulk density of the soil to be extracted. This can therefore lead to a significant increase in soil removal.US4152027A discloses improvements in shield-type hydraulic tunnel boring machines capable of accurately detecting occurrences, shapes, dimensions, and the like of excess excavation due to accidental collapses of the tunnel wall in soft and unstable ground.

[0005] The invention is based on the technical problem of providing a method and a tunnelling device of the type mentioned at the outset, with which an excessively high extraction rate of overburden can be detected at an early stage more reliably than with the prior art.

[0006] The technical problem is solved with regard to the method by the features of claim 1 and with regard to the propulsion device by the features of claim 8. Preferred embodiments of the method according to the invention and of the propulsion device according to the invention are set out in the dependent claims.

[0007] With regard to the method, it is therefore proposed that, for overburden control during excavation in the ground, the earth pressure exerted by the earth on a tunneling device driven through the ground is monitored by means of a pressure control element that can be extended from the circumference of the tunneling device. This avoids inaccurate quantity or volume measurement of the overburden. The pressure control can determine whether the surrounding soil is becoming increasingly loose, which could indicate that too much earth has been excavated in relation to the excavation speed. In this case, measures can be taken, for example, to increase the excavation speed and / or reduce the amount of overburden delivered per unit of time. The tunneling device can be any machine, e.g. a full-face machine or a partial header. The application of the method is also independent of the type of extraction of the excavated earth, e.g.by means of a bucket conveyor, screw conveyor or flush conveyor.

[0008] The pressure control element can have various geometries. For example, a pressure control element is conceivable whose outer wall, when not extended, continues the shape of the peripheral wall forming the circumference of the propulsion device, and which executes a pivoting movement when extended. Thus, the pressure control element could, for example, protrude from the peripheral wall of the propulsion device in a fin-like manner when extended.

[0009] Not every soil composition may be suitable for implementing the inventive method. However, the method is adaptable to various soil compositions. The inventive method does not require the detection of subtle changes in ground pressure in order to respond with changes in the advance rate and / or the amount of excavated material per unit of time. The inventive method is already effective if a significant decrease in ground pressure can be detected, which indicates excessive soil extraction.

[0010] The method according to the invention can be carried out in such a way that the pressure control element is preferably moved hydraulically or pneumatically.

[0011] The method according to the invention can be carried out in such a way that a change in the ground pressure is detected by measuring the pressure in a pressure medium used in the hydraulic or pneumatic system and / or by means of a change in the position of the pressure control element.

[0012] If too much soil is removed, the soil pressure on the propulsion system and thus on the pressure control element decreases. This causes the pressure control element to move outward, resulting in a reduction in pressure in the pressure medium, which could be water or oil, for example.

[0013] In order to be able to detect a reduction in ground pressure, the pressure control element protrudes at least partially from the peripheral wall of the tunnelling device, e.g. by a value of up to 30 mm or more. In order to keep the position of the pressure control element stable despite a reduction in ground pressure, the pressure of the pressure medium is automatically adjusted, i.e. reduced, and preferably when the pressure falls below a limit value or there is a pressure change, a signal is automatically issued or an action is triggered in order to reduce the tunnelling speed and / or the amount of excavated material delivered per unit of time. If a sufficient increase in ground pressure is detected by the pressure control element, the tunnelling speed and / or the amount of excavated material delivered per unit of time can be increased again.

[0014] Alternatively, a change in the position of the pressure control element can be detected at a preset initial pressure of the pressure medium. First, the pressure control element can be brought into an initial position in which the pressure control element protrudes at least partially from the peripheral wall of the jacking device, e.g. by up to 20 mm or up to 50 mm. Larger values ​​are also possible. The pressure control element is preferably blocked against movement from the initial position towards the interior of the jacking device so that up to a maximum load only movement into the ground or from there back to the initial position is possible. To prevent damage if the maximum load is exceeded, a pressure relief valve, for example, can be used.

[0015] The initial pressure can be selected depending on the soil condition and / or composition. It may be advantageous to set the initial pressure so that it is a fraction of the passive earth pressure, e.g., at most 20%, more preferably at most 10%, or more preferably at most 5%. In this case, only a massive local reduction in the passive earth pressure in the ground allows the pressure control element to move outwards, which is a strong indication of significant over-extraction. Since, in an advantageous embodiment of the method according to the invention, only a small fraction of the passive earth pressure is selected for the initial pressure, this does not necessarily have to be determined precisely in advance. Rather, a rough estimate of the passive earth pressure may be sufficient for known or assumed soil compositions.

[0016] Thus, the soil pressure acting on the tunneling equipment can be monitored by measuring the pressure in the pressure medium and / or by measuring the position or displacement of the pressure control element. The term "soil pressure" generally refers to the pressure exerted by the soil under the given conditions on a surface, in this case, particularly on the tunneling equipment, and is used here to distinguish it from the technical terms "passive earth pressure" and "active earth pressure."

[0017] Preferably, the pressure control element is arranged in the area of ​​the roof, i.e. at an upper point of the tunnelling device, since this is where a reduction in the ground pressure due to excessive extraction is most noticeable.

[0018] The pressure control element should preferably be installed as close as possible behind the tip of the machine in order to detect over-extraction of soil at an early stage.

[0019] In the following, an exemplary embodiment of the method according to the invention and of the propulsion device according to the invention is illustrated by means of figures.

[0020] It shows Fig. 1 : in lateral cross-section the front end of a propulsion device with pressure control element, Fig. 2 : in an enlarged section of the tunnelling equipment according to Fig. 1 the pressure control element in the retracted position, Fig. 3 : the pressure control element according to Fig. 2 in the retracted state in the axial cross-section, and Fig. 4 : the pressure control element according to Fig. 2 in lateral cross-section in extended state.

[0021] Fig. 1shows a schematic lateral cross-section of the front part of a tubular propulsion device having a peripheral wall 3, comprising a drill head 1 and a motor unit 2 for driving the drill head 1. The peripheral wall 3 can be formed by a cutting shoe in the case of controlled drilling. A wedge-shaped pressure control element 5 is arranged so as to be pivotable about a pivot axis 6 in a box-shaped receptacle 4 fixed to the peripheral wall 3. The pressure control element 5 is articulated to a piston 7 of a hydraulic cylinder 8. Via the hydraulic cylinder 8 and the piston 7, referred to as the hydraulic system 11 as a whole below, the pressure control element 5 can be brought into an extended position in which an upper contact surface 9 of the pressure control element 5 projects at least partially beyond the circumference of the peripheral wall 3.

[0022] Fig. 2shows an enlarged section of the propulsion device with the box-shaped holder 4, the pressure control element 5, the piston 7 and the hydraulic cylinder 8 together with the soil 10 surrounding the propulsion device. In the retracted state, the pressure control element 5 is essentially flush with the circumference of the peripheral wall 3 with its contact surface 9. Fig. 3 shows the situation according to Fig. 2 in axial cross-section. Fig. 4 shows in a Fig. 2 corresponding illustration, the pressure control element 5 is in an extended position in which the contact surface 9 of the pressure control element 5 projects into the ground 10.

[0023] The exemplary procedure is as follows: From a starting pit (not shown here), the tunneling device, with, for example, a rotating drill head 1, is driven into the soil 10. The drill head 1 has a slight overcut relative to the circumference of the peripheral wall 3 of the tunneling device. For example, lubricating material 12, such as bentonite, can be introduced into a space created by the overcut via lines (not shown here) and openings in the peripheral wall 3. This lubricating material reduces the friction between the peripheral wall 3 and the soil 10.

[0024] Excavated soil 10, i.e., the overburden, can be transported towards the starting pit via hoses (not shown here) with the addition of a liquid, for example, water. Alternative methods of removal are also possible, for example, via a screw or bucket conveyor located inside the propulsion device (also not shown here). With the penetration of the propulsion device into the soil 10, or shortly thereafter, the pressure control element 5 is moved into an extended position (see Fig. 1 and Fig. 4 ) so that the contact surface 9, which is preferably flat but can also take on other shapes, comes into contact with the surrounding soil 10.

[0025] The pressure of a pressure medium in the hydraulic system 11 is adjusted when the pressure control element 5 is extended so that a balance is maintained between the torques exerted on the pressure control element 5 via the pressure of the soil 10 on the one hand and via the piston 7 on the other. If the pressure of the soil 10 decreases, the pressure in the hydraulic system 11 must be reduced accordingly to maintain the position of the pressure control element 5, so that the reduction in the soil pressure can be determined via the pressure in the hydraulic system 11. Such a reduction in the soil pressure suggests that excessive extraction of soil 10 has occurred, so that as a countermeasure, for example, the conveying rate of the overburden can be reduced and / or the advance of the propulsion device can be increased in order to prevent subsidence or undesired loosening of the soil 10.

[0026] As an alternative to measuring the pressure in the hydraulic system 11, or in parallel thereto, the extension length of the piston 7 or the position of the pressure control element 5 relative to other parts of the jacking device, e.g., to the peripheral wall 3, can also be measured using suitable methods in order to determine any change in the earth pressure exerted on the pressure control element 5 by the earth 10. For this purpose, an initial pressure can be set in the hydraulic system which is subjected to a fraction of, e.g., 10% of the passive earth pressure of the surrounding earth 10. From an initial position of the pressure control element 5, in which the pressure control element 5 protrudes with its contact surface 9 from the peripheral wall 3 of the jacking device, e.g., by a maximum of 30 mm, the pressure control element 5 is pushed outwards when the earth pressure is less than 10% of the passive earth pressure. This movement can be used to determine any excessive removal of overburden in the earth 10.

[0027] To prevent soil 10 from penetrating the receptacle 4, the receptacle 4 can be filled with a material that does not interfere with the functions of the hydraulic system 11, such as bentonite. This material is preferably at a pressure at least substantially equal to the pressure of the lubricating material 12, in order to prevent the entry of the lubricating material 12, possibly mixed with soil 10.

[0028] In addition, it is conceivable not to pivot the pressure control element 5 or not only to pivot it, but to move it with a translational movement.

[0029] The features of the device and the method shown in the exemplary embodiments can be replaced or supplemented within the meaning of the invention by alternative or further features, such as those shown in the general part of the description or those apparent to a person skilled in the art. List of reference symbols

[0030] 1Drill head 2Motor unit 3Circumferential wall 4Holder 5Pressure control element 6Swivel axis 7Piston 8Hydraulic cylinder 9Contact surface 10Soil 11Hydraulic system 12Lubricant

Claims

1. Method for creating a borehole in soil (10) for the installation of pipes, wherein an excavation device having a rotating drill head (1) and a peripheral wall (3) is driven into the soil (10) starting from a start pit, wherein the overburden loosened by the drill head (1) is transported away in the direction of the start pit, wherein a pressure-monitoring element (5) is provided for monitoring the amount of overburden removed during excavation in the soil (10), the soil pressure exerted by the soil (10) on the excavation device being monitored by means of the pressure-monitoring element, characterized in that the pressure-monitoring element (5) is arranged in a box-like receptacle (4) such that it can pivot about a pivot axis (6), in that the pressure-monitoring element (5) is wedge-shaped and has a contact surface (9), in that the pressure-monitoring element (5) is connected in an articulated manner to a piston (7) of a hydraulic cylinder (8), via which the pressure-monitoring element (5) is pivoted into an extended position protruding from the peripheral wall (3), in that the pressure-monitoring element (5) is moved to an extended position when the excavation device penetrates the soil (10) or shortly thereafter, so that the contact surface (9) comes into contact with the surrounding soil (10).

2. Method according to Claim 1, characterized in that the pressure-monitoring element (5) is moved hydraulically or pneumatically.

3. Method according to Claim 2, characterized in that a change in the soil pressure is determined by means of measuring the pressure in a pressure medium used in the pneumatic or hydraulic system (11) and / or by means of a change in position of the pressure-monitoring element (5).

4. Method according to any of the preceding claims, characterized in that a fraction, preferably at most 20%, further preferably at most 10%, further preferably at most 5%, of the passive soil pressure of the surrounding soil (10) is applied to the pressure medium.

5. Method according to any of the preceding claims, characterized in that the pressure of a pressure medium acting in the hydraulic cylinder (8) is adjusted in order to maintain the extended position.

6. Method according to Claim 5, characterized in that, when a limit value for the pressure or a change in pressure is undershot, a signal is emitted or an action is triggered in an automated manner in order to reduce the excavation speed and / or the amount of overburden conveyed per unit of time.

7. Method according to any of the preceding claims, characterized in that an initial pressure of the pressure medium is preset and a change in the position of the pressure-monitoring element (5) is determined.

8. Excavation device for carrying out the method according to any of Claims 1 to 7, having a drill head (1), a motor unit (2) for driving the drill head (1) and a peripheral wall (3), comprising a pressure-monitoring element (5) which is arranged on the peripheral wall (3) and can be extended beyond the periphery (3) of the excavation device and is arranged in the region of the ridge of the excavation device, characterized in that pressure-monitoring element (5) is arranged in a box-like receptacle (4) such that it can pivot about a pivot axis (6), in that the pressure-monitoring element (5) is wedge-shaped and has a contact surface (9), in that the pressure-monitoring element (5) is connected in an articulated manner to a piston (7) of a hydraulic cylinder (8), via which the pressure-monitoring element (5) can be moved to an extended position, and in that the contact surface (9) at least partly protrudes beyond the periphery of the peripheral wall (3) in the extended position of the pressure-monitoring element (5).

9. Excavation device according to Claim 8, characterized in that the pressure-monitoring element (5) is operated pneumatically or hydraulically.

10. Excavation device according to Claim 9, characterized by pressure-measuring means for measuring a pressure medium in the pneumatic or hydraulic system (11).

11. Excavation device according to any of Claims 8 to 10, characterized by position-measuring means for measuring the position or a change in position of the pressure-monitoring element (5).

12. Excavation device according to any of Claims 8 to 11, characterized in that the pressure-monitoring element (5), by way of its contact surface (9), is flush with the peripheral wall (3) in the retracted state.

13. Excavation device according to any of Claims 8 to 12, characterized in that the contact surface (9) of the pressure-monitoring element (5) protrudes into the soil (10).