EP1001134A1 - Anchoring device with a seismic sensor - Google Patents

Abstract

The arrangement has an anchoring rod (21) and an anchoring head with at least one vibration sensor mounted on the anchoring rod. Several vibration sensors (25-27) can be mounted at different relative positions in relation to the longitudinal axis of the anchoring rod. The sensors can be mounted in a fitting on the end of the rod remote from the anchoring head with a cable guide (22) from the sensors to the head. Independent claims are also included for a system anchoring arrangement for tunnel construction and for a method of high resolution seismic tomography.

Description

The invention relates to an anchoring device, in particular an anchor element for foundation engineering, rock construction, mining or Solid construction, and a seismic sensor, e.g. a geophone or an accelerometer, as well as methods for spatially high resolution Seismic and seismic tomography in the earth's crust or in structures, especially for underground seismic Mountain exploration (so called "Tunnel Seismic Prediction" or TSP).

When building tunnels in the mountains through a full excavation with tunnel boring machines (TBM) is a seismic exploration of the Mountains to examine the bedrock in the direction of advance. The preliminary investigation is aimed at building technology relevant mountain changes in the vicinity of the tunneling to predict and rock mechanical parameters in the heading area to win. A well-known advance investigation process, that of the company "Amberg Meßtechnik" (Scweiz) with The system "TSP 202" is implemented as follows explained with reference to FIG. 4.

Fig. 4 shows a schematic side view of the propulsion of a Tunnels 40 in a mountain 41 with a tunnel boring machine 42. For exploration, tunnel 40 is located behind the tunnel boring machine 42 (or also when blasting without tunnel boring machine) with individual detonations or detonating cord 43 a series of seismic blasts triggered, causing Vibration signals or acoustic signals especially in Spread the direction of advance. These signals are in areas changed rock strength (disturbances, rock changes) due to the changing seismic rate of propagation partially reflected in these zones. The reflected Signals are received from a seismic transducer 44 detected. Zones 41a and 41b provide different terms of the reflected signals ("echo delays") from which the Spatial position of the zones, the intersection with the tunnel axis and the distance to the tunnel face 45 can be calculated. With the system TSP 202, the transducer 44 consists of a non-positive in Mountain piping brought in several groups of highly sensitive Accelerometer contains. The series of seismic blasts is caused by the individual explosions or the detonating cord 43 and an associated ignition control.

The conventional prediction method has the following Disadvantage. The attachment of the transducer 44 requires the Drilling a separate hole and cementing the Piping. In addition, shot holes for the individual explosions or the detonating cord 43 are introduced. These measures are labor and time consuming. The real one seismic measurement requires an interruption of the tunneling to release the charges in the shot holes and for seismic recording, creating an additional Time expenditure arises from the actual tunneling operation disturbs. Another problem is the limitation of the conventional system to a few (e.g. four) measuring channels, whereby the heterogeneities in the mountains are only recorded inaccurately can. After all, the conventional system is based on a two-dimensional one Detection of heterogeneity in the mountains, namely in relation to the direction of advance or tunnel axis and on the radial distance from this limited. So only an incomplete picture of the mountains surrounding the tunnel and thus only an incomplete prediction and documentation of the tunnel-relevant parameters can be achieved.

It is also well known to take place in mountain tunnel construction a massive expansion an anchoring expansion (System anchorage) of the tunnel walls. It is known, Rock anchors, for example, made of glass fiber reinforced plastic (so-called "GFK" anchors). GRP anchors, for example distributed by the company "H. Weidmann AG" (Switzerland). A GRP anchor consists of an anchor rod, one Anchor plate and an anchor nut, at least of which Anchor rod made of glass fiber reinforced plastic. GRP anchor are in appropriate, from the tunnel into the mountains introduced anchor holes with synthetic resin adhesive and glued (glue anchor). Alternatively, so-called injection anchors (from GRP) used; these are hollow tubes where the two-component synthetic resin adhesive is pressed through the pipe will exit at the bottom open end and from there back the Fills and glues the annular gap between the anchor and the borehole wall. Depending on the application, the attachment is comb or hedgehog-like in the tunnel wall transverse to the direction of advance or as anchoring in advance in the direction of advance. GRP anchor for example in the publication "Safety and fastening technology in underground construction "in" Schweizer Baublatt "(No. 24, 1994).

From Wo 98/19044 an anchoring device is on the Basis of a GRP anchor known to measure strain in the mountains is set up. In the anchoring device integrated at least one light guide, the at least one Has Bragg's grating and for strain or force measurement in the walls of cavities, for example in the mountains or is installed in buildings. Such GRP anchors with integrated light guides also allow quickly changing Strain measurements (a few kHz), the equipment expenditure for a high resolution measurement of the seismic vibration amplitude with the fiber optic system, however, is much higher than for the geophone transducers.

The above using the example of seismic exploration in tunnel construction Problems discussed also generally occur with seismic Investigations of the earth's crust or in construction engineering (e.g. large buildings such as power plant walls, pile foundations and Like.) on if in the examined floor or building area Heterogeneities detected by sound or vibration measurements should be.

The object of the invention is therefore an improved device for vibration analysis, especially in tunneling technology, Seismics and construction technology, with which the respective vibration tests with reduced time expenditure and increased accuracy can be performed. It should in particular be possible from the conventional two-dimensional to proceed to three-dimensional investigations. The object of the invention is also an improved method to specify using such a device.

The above tasks are carried out with an anchoring device, a transducer rod of a system anchor and a tomographic Vibration measurement method with the features according to the claims 1, 7, 9 and 11 solved. Beneficial Embodiments and applications of the invention result from the dependent claims.

According to a first important aspect of the invention an anchoring device (or: anchor element), in particular with an anchor rod and an anchor head, indicated at least one vibration sensor on or in the anchoring device is appropriate. As a vibration sensor are, for example Geophones and / or accelerometers can be used. It is preferably an integrated attachment in the body of the anchor rod or provided at the end remote from the anchor head, so that the vibration sensor (s) with the anchoring device form a unit. According to a preferred embodiment becomes a GRP rock anchor with at least one geophone and / or accelerometer. An inventive Anchoring device can, however, generally also be based other types of rock anchors. It can also be provided that the at least one vibration sensor by at least one other sensor (e.g. sound sensor, Sensor for recording further geophysical values, such as. Temperature, pressure or the like) is replaced.

According to a second important aspect of the invention specified a pick-up rod that serves as a carrier for at least one Vibration sensor is designed. As a vibration sensor are, for example, geophones and / or accelerometers applicable. The sensor rod is made of metal (e.g. steel) or preferably made of glass fiber reinforced plastic. The Pickup rod can, for example, like the anchor rod of the invention Anchoring device (without anchor head) built his.

Another important aspect of the invention is in it, from a variety of the aforementioned anchoring devices or pick-up bars vibration receiver assemblies for spatially high-resolution reflection and refraction seismics or seismic tomography. A preferred one Application is the design of a system anchor during expansion a tunnel wall with at least partial use of the mentioned anchoring devices, so that a seismic Receiver arrangement is created. When using the transducer rods can also have a system arrangement of these, for example provided in a tunnel wall or building his.

According to another important aspect of the invention becomes a seismic exploration process for tunnel construction in the bedrock of a mountain range using the mentioned Vibration receiver arrangement described.

The invention has the following advantages. The integration allowed by vibration sensors in anchoring devices the attachment of the vibration sensors to the interested Measuring locations simultaneously with the installation of the Anchoring devices e.g. when removing a tunnel wall or for applications in construction technology. The invention Anchoring device thus has a double function. On the one hand it is the carrier of the vibration sensors and on the other hand it has a securing effect for the expanded Wall. This double function differs the one according to the invention Anchoring device of all conventional Bearings of vibration sensors. This advantage also applies the structure of the pick-up rod according to the invention, if this has a hedging effect. This will save time considerably reduced for carrying out the measurements. Further a relatively dense sensor arrangement is created, which a three-dimensional measurement evaluation with increased accuracy allowed. In particular the use of geophones or Accelerometers is advantageous in that a reproducible Obtaining measured values regardless of any malfunctions Field conditions can be realized. It can be sprawling Heterogeneities and / or deformations in the rock or detected and located in a building. The acquisition of measured values can be directly on the anchoring device respectively. The preliminary investigation method according to the invention can routinely during tunnel construction without special circumstances be implemented. The anchoring device according to the invention with integrated sensor is particularly good for detection dynamic signals, such as those used in reflection seismics occur.

Further advantages result from the fact that the measuring and evaluation system mobile for seismic tomography can. The measuring and evaluation system is used, for example, in the tunnel or in the building at the location of interest to the respective Anchoring devices connected. The measured values of the Vibration sensors are recorded and evaluated. The measuring and Evaluation system can also be fixed in the tunnel and with connected to a variety or all anchoring devices and set up for a parallel or serial request be so that after suitable vibration generation or Suggestion continuously pictures of the surrounding mountains or building have it determined.

Fig. 1

schematische Längs- und Querschnittsansichten eines Tunnels mit einer Anordnung von Verankerungseinrichtungen oder Aufnehmerstäben gemäß der Erfindung;

Fig. 2

eine vergrößerte, schematische Schnittansicht des Endes eines Ankerstabes einer erfindungsgemäßen Verankerungseinrichtung;

Fig. 3

eine schematische Perspektivansicht zur Illustration der erfindungsgemäßen Verfahrensweise; und

Fig. 4

eine schematische Schnittansicht zur Illustration eines herkömmlichen Vorauserkundungsverfahrens (Stand der Technik).

Further advantages and details of the invention will become apparent from the accompanying drawings. Show it:

Fig. 1

schematic longitudinal and cross-sectional views of a tunnel with an arrangement of anchoring devices or pick-up rods according to the invention;

Fig. 2

an enlarged, schematic sectional view of the end of an anchor rod of an anchoring device according to the invention;

Fig. 3

a schematic perspective view to illustrate the procedure according to the invention; and

Fig. 4

is a schematic sectional view for illustrating a conventional preliminary investigation method (prior art).

The invention is based on the example of an anchor for explains the mountain tunnel construction, but is not on this Application limited, but also with other seismic Measurements in the earth's crust or in construction engineering applicable. Furthermore, in addition to or instead of those described below Integration of vibration sensors in an anchoring device this with additional sensors, e.g. a strain sensor according to the aforementioned WO publication or the above Sensors for geophysical quantities, can be provided.

1 shows a tunnel 10 in a pressurized mountain area 11 with a system anchor 12 in longitudinal (A) and transverse (B) sectional view (after S. Flury et al. in "Tunnel", 1998, p. 26 ff.). The system anchor 12 comprises side wall anchors 121 and anchoring 122, which serves as a face protection serves. There are also the in-situ concrete base 101, a Shotcrete test 102, in-situ concrete cladding 103 (Fig. 1 (A)) and a deformable steel installation 104 (Fig. 1 (B)) shown. The tunnel diameter is, for example, in Range from 6 to 12 m.

The attachment of the wall anchors 121, 122 of the system anchor 12 or of transducer rods according to a system arrangement the tunnel expansion known per se and the one to achieve a certain stability requirements the density and orientation of the wall anchors in relation to the tunnel wall. Accordingly, the wall anchors 121 and the pre-anchor are 122 hedgehog-like, radial or axial in the Mountain rock arranged extending. However, it may be even more inclined wall anchors 123 used, which differ on the radial arrangement of the side wall anchors 121 the tunnel axis 13 form an angle that is less than 90 ° is. The only shown in the upper part of Fig. 1 (A) or (B) Sloping wall anchors 123 can be installed in all tunnel areas be and in relation to the angle of attack against the Tunnel axis 13 vary. The inclined wall anchors 123 Although also an expansion function, it also serves in particular to improve the resolution of the seismic tomography of the surrounding mountains (see below).

As a wall anchor 121-123 are all forms of wall anchors or Suitable anchor elements that allow integration of sensors. However, GRP anchors are preferred. According to the invention it is contemplated that some or all of the wall anchors 121-123 according to the invention Anchoring devices are or at the corresponding Locations according to the invention are provided details of which are given below with reference to FIG. 2 are explained. The wall anchors according to the invention with at least are equipped with a vibration sensor, form a Receiving antenna arrangement for spatially high-resolution seismic Mountain tomography.

Details of an anchoring device according to the invention, which as at least one of the wall anchors in the hedgehog-like 1 can be provided in the schematic sectional view shown in FIG. 2. An inventive Sensor rod is constructed analogously. Fig. 2 (A) shows that from the anchor head (not shown) or in the anchored state End of a wall anchor facing away from the tunnel axis 20 with the anchor rod 21, which contains a cable guide 22, an anchor rod attachment 23, which has a connection area 24 is connected to the anchor rod 21 and three vibration sensors 25, 26, 27 contains, and a rod tip 28, the for piercing the adhesive cartridge when gluing in the wall anchor 20 is set up in the rock. The dimensions of the wall anchor 20 are the usual dimensions of a GRP anchor customized. Accordingly, the diameter of the anchor rod 21 e.g. approx. 2 to 3 cm. The cable guide 22 for Implementation of the electrical signal lines (not shown) for the vibration sensors 25, 26, 27 has one Diameter of approx. 5 mm (around 10 mm for injection anchors). The The diameter of the rod attachment 23 is that of the anchor rod 21 customized. The axial length of the rod attachment 23 is in Dependence on the number and size of the vibration sensors chosen and is for example approx. 6 cm. The connection area 24 between the rod attachment 23 and the anchor rod 21 is, for example, by an adhesive, plug or screw connection educated.

The rod attachment 23 contains several vibration sensors, which include, for example, geophones and / or accelerometers. The vibration sensors should preferably have a measurable frequency range, which ranges up to 2.5 kHz to 3 kHz, in order to achieve seismic waves of approx. 5000 m / s in hard rock a resolution of approx. To achieve 1 to 2 m. In addition, the vibration sensors should be dimensioned small enough to be attached to the anchor rod attachment. They are preferably miniaturized vibration sensors that are commercially available per se, which are shown here only schematically as square or circular. A geophone, for example of the type GS-14-LD, GS-14-L3 or GS-14-L9, can have typical dimensions a · b of approx. 16 x 18 mm ² . The three geophones used according to the invention preferably work in all directions, ie they can be attached in all spatial directions.

The vibration sensors 25, 26, 27 are in the rod attachment 23 arranged that the evaluation of the echo times or the Time pattern of seismic vibrations received by a common vibration excitation and reflection on mountain heterogeneities have been caused in relation to the spatial direction of propagation of the respective vibration measurable are. For this purpose, a first vibration sensor 27 is axially open the longitudinal axis of the wall anchor 20 is arranged. The remaining Vibration sensors 25, 26 are in relation to the longitudinal axis the wall anchor 20 is offset off-center in different directions, each adjacent to the outer wall of the rod attachment 23 arranged. The geometry of this in relation to the longitudinal axis staggered arrangement is schematic in Fig. 2 (C) Cross-sectional view illustrated. For orientation of the sensor arrangement in the borehole contains the GRP anchor on the anchor head a marker.

The geophones used as vibration sensors are application-dependent chosen. With a natural frequency of approx. 20 Hz are used based on electrodynamic measuring principles Geophones preferably for speed measurement, whereas Accelerometer e.g. on a piezoelectric basis with Natural frequencies in the kHz range as accelerometers serve.

The structure of the rod attachment 23 according to FIG. 2 (A) can be application-dependent be modified. This affects both the arrangement as well as the number of individual recipients that are larger or less than 3. The arrangement can take the form of a with respect to the longitudinal axis of the anchor rod Tripod must be chosen.

The attachment of the vibration sensors in the rod attachment 23 on The end of the wall anchor 20 represents a particular advantage of the invention The geophones are non-positively attached to the anchor and over the rod body 21 or the rod attachment 23 and the two-component bonding directly in mechanical contact with the surrounding rock. The wall anchor 20 will through the rod attachment 23 in its stability and function not weakened. However, with an alternative design be provided that the vibration sensors are not in one Rod attachment, but directly in the body of the anchor rod 21 are integrated if this has a sufficiently large diameter owns or the vibration sensors sufficiently small (e.g. designed as microsystems).

To produce an anchoring device according to the invention becomes essentially more conventional than in the manufacture GRP anchors proceeded, however, during manufacture the glass fiber reinforced plastic from the start the cable guide 22 and the design of the connection area 24 are provided. The rod attachment 23 with the Rod tip 28 can then be used as an independently manufactured cap Pulling in the signal lines (not shown) on the connection area 24 are put on.

An embodiment of the procedure according to the invention is explained below with reference to FIG. 3. Fig. 3 shows a tunnel 30 in a schematic perspective illustration in the mountains 31 with a tunnel boring machine 32 and a system anchor 33, which corresponds to the representation of FIG. 1 is trained. The tunnel boring machine 32 is with a seismic Excitation device 34 (frequency around 2-6 kHz) equipped. The excitation device 34 is, for example mechanical, electrodynamic or piezoelectric generation Seismic vibrations are provided and in the head the tunnel boring machine 32 or in a leading borehole appropriate. If in practice no tunnel boring machine, but normal blasting is used, the Invention can be implemented analogously.

According to the invention, the high-resolution reflection or refraction seismics or seismic Tomography performed by starting from the excitation device 34 seismic waves in the rock 31 radiated and with wall anchors the system anchor 33 seismic Waves received at heterogeneities 31a, 31b have been reflected in the mountain rock 31. To the with Vibration sensors equipped wall anchors according to the invention the system anchor 33 becomes the reflected signals time, direction and / or amplitude selective and one Evaluation device (not shown) supplied. In the Evaluation device, the signal evaluation and generation a picture of the mountain range of interest with the heterogeneities or reflecting therein Zones.

Deviating from the positioning of the excitation device in the Alternatively, it can also be provided that the seismic excitation in the already completed tunnel, i.e. behind the tunnel boring machine 32, as is the case, for example is known from the conventional system TSP 202.

Claims (13)

Anchoring device with an anchor rod (21) and an anchor head,
marked by
at least one vibration sensor (25-27) attached to the anchor rod (21). Anchoring device according to claim 1, wherein several Vibration sensors (25-27) are provided, each different Relative positions with respect to the longitudinal axis of the Have anchor rods (21). Anchoring device according to claim 1 or 2, wherein the vibration sensors (25-27) in a rod attachment (23) on End of the anchor rod (21) facing away from the anchor head are and the anchor rod (21) a cable guide (22) of the Vibration sensors (25-27) towards the anchor head. Anchoring device according to one of the preceding claims, provided with the three vibration sensors (25-27) are arranged according to an orthogonal tripod are. Anchoring device according to claim 4, wherein the Vibration sensors (25-27) geophones and / or accelerometers include. Anchoring device according to one of the preceding Claims, in which the anchor rod (21) made of glass fiber reinforced Plastic is made. Transducer rod, which is a carrier for at least one Vibration sensor (25-27) forms in the transducer rod is integrated. Sensor rod according to claim 7, which is like an anchor rod Anchoring device constructed according to one of claims 1 to 6 is. System anchor for tunnel construction or for building construction technology consisting of a variety of wall anchors, of which at least one wall anchor by an anchoring device is formed with the features according to any one of claims 1-6. System arrangement for tunnel construction or construction technology, consisting from a large number of pick-up rods according to one of the Claims 7 or 8. Process for high resolution seismics or tomography of Mountain zones or structures in which in the rock or Structure sound waves excited and echo waves due to heterogeneity have been reflected, with at least one anchoring device according to one of claims 1-6 or with at least one pick-up rod according to one of claims 7 or 8 can be detected. The method of claim 11, wherein a system anchor (12, 33) for high-resolution seismics or tomography of the Mountains is used. The method of claim 12, wherein the excitation is seismic Waves in the mountains with an excitation device (34) on the head of a tunnel boring machine (32) or in one leading borehole or in a blasting operation.

Images