CN111141253B - System and method for monitoring deep settlement of soil behind shield tunnel wall - Google Patents
System and method for monitoring deep settlement of soil behind shield tunnel wall Download PDFInfo
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- CN111141253B CN111141253B CN201911239665.7A CN201911239665A CN111141253B CN 111141253 B CN111141253 B CN 111141253B CN 201911239665 A CN201911239665 A CN 201911239665A CN 111141253 B CN111141253 B CN 111141253B
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- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
Abstract
The application aims to provide a monitoring system and a method for deep settlement of a soil body behind a shield tunnel wall, wherein the monitoring system comprises a data acquisition device and a data processing system; the data acquisition device comprises an anchor head, an LCI displacement meter, a PVC pipe, a first optical fiber cable, a filter screen, a lantern ring, a first micro grouting pipe and a second micro grouting pipe, wherein the LCI displacement meter is arranged in the PVC pipe, the upper end of the LCI displacement meter is rigidly connected with the anchor head, the lower end of the LCI displacement meter is connected with the data processing system through the first optical fiber cable, the anchor head extends into the PVC pipe and is inserted into the in-situ soil body, the lantern ring is sleeved on the PVC pipe, the filter screen is embedded in the lantern ring, and the first micro grouting pipe and the second micro grouting pipe are bound and arranged in the PVC pipe. The scheme breaks through the dilemma that the existing shield tunnel segment cannot be drilled and measured under the sealing condition; meanwhile, the method has the advantages of high precision, strong anti-electromagnetic interference and suitability for long-term monitoring of the tunnel of the optical fiber sensing technology, can completely meet the requirement of automatic monitoring, and can be applied to the actual conditions of engineering.
Description
Technical Field
The application relates to the technical field of tunnel engineering monitoring, in particular to a system and a method for monitoring deep settlement of a soil body behind a shield tunnel wall based on a Low-coherence interference (LCI) technology.
Background
The 3D printing technology, as an emerging technology of Rapid prototyping (Rapid prototyping), has been developed rapidly in recent years, and its basic ideas are as follows: and (3) obtaining the three-dimensional entity by processing layers and adding and forming layer by using the bondable material based on the digital model file.
With the construction of shield tunnels becoming the main construction form of traffic tunnels such as subways and underwater tunnels, in recent years, with the large-scale construction of underground shield tunnels, the disaster problems caused during the construction and operation of underground shield tunnels become the focus of attention, such as the disaster problems of concrete deterioration, uneven lining stress and damage, rear cavities and the like, and the generation of many disaster problems is related to the deformation and settlement of soil bodies.
Although the traditional displacement meter has the advantages of low price, convenience in operation and the like, the traditional displacement meter has the defects of large size, low measurement accuracy and incapability of measuring in real time, so that the traditional displacement meter cannot be used in many scenes.
The multipoint displacement meter is a common measurement means for measuring the internal deformation of the surrounding rock of the cavern at present, and as shown in a multipoint displacement meter installation buried grouting method provided by the patent number CN103290827A, a large hole needs to be drilled in the method, but a shield tunnel segment is a sealing body and cannot be freely perforated.
The optical fiber sensor is used as a new monitoring technology, is more and more applied to shield tunnel disease monitoring, has the advantages of high monitoring precision, strong electromagnetic interference resistance and the like, and has a good development prospect.
Therefore, it is very necessary to develop a high-precision monitoring method which meets the actual engineering situation in the actual scene of monitoring the soil above the tunnel.
Disclosure of Invention
An object of the present application is to provide a system and a method for monitoring deep settlement of soil behind a shield tunnel wall.
According to an aspect of the application, a system for monitoring deep settlement of soil behind a shield tunnel wall is provided, and the system comprises: the monitoring system comprises a data acquisition device and a data processing system; the data acquisition device comprises an anchor head, an LCI displacement meter, a PVC pipe, a first optical fiber cable, a filter screen, a lantern ring, a first micro grouting pipe and a second micro grouting pipe, wherein the LCI displacement meter is arranged in the PVC pipe, the upper end of the LCI displacement meter is rigidly connected with the anchor head, the lower end of the LCI displacement meter is connected with the data processing system through the first optical fiber cable, the anchor head extends into the PVC pipe and is inserted into in-situ soil, the lantern ring is sleeved on the PVC pipe, the filter screen is embedded in the lantern ring, and the first micro grouting pipe and the second micro grouting pipe are bound and arranged in the PVC pipe.
Furthermore, the filter screen is made of a novel polyurethane material, the aperture of the filter screen is set according to the size of the slurry, the principle of blocking most of the slurry from passing is followed, and the anchor head and the micro grouting pipe are allowed to be suspended and fixed on the filter screen.
Furthermore, the first miniature grouting pipe is positioned above the filter screen, the direction of a grouting hole faces upwards, the second miniature grouting pipe is fixed on the filter screen, and the direction of a grouting opening faces downwards.
Further, the LCI displacement meter comprises an LCI optical fiber sensor and a 3D printed cylinder, and the LCI optical fiber sensor is arranged on the central axis of the cylinder.
Further, wherein the data processing system comprises: the LCI displacement meter comprises a broadband light source, a second optical fiber cable, a third optical fiber cable, a first coupler, a second coupler, an optical mobile scanning platform, a tail-end-cut optical fiber and a signal acquisition and processing system, wherein a signal arm of an LCI optical fiber sensor in the LCI displacement meter is connected with the broadband light source through the first optical fiber cable, a reference arm of the LCI optical fiber sensor is connected with the signal acquisition and processing system through the third optical fiber cable, the signal arm of the LCI optical fiber sensor is provided with the first coupler, the reference arm of the LCI optical fiber sensor is provided with the second coupler, the first coupler is connected with the second coupler through the second optical fiber cable, the second coupler is connected with the tail-end-cut optical fiber, and the reference arm of the LCI optical fiber sensor is matched with a reflector on the optical mobile scanning platform;
light emitted by the broadband light source passes through the first coupler along the first optical fiber cable and then reaches the LCI optical fiber sensor, the light enters the LCI optical fiber sensor and then is reflected, the light passes through the first coupler and then reaches the second coupler, the light is divided into two paths, the two paths of light are respectively reflected by the optical fiber with the flattened tail end and the reflector on the optical moving platform, the two paths of reflected light are converged and interfered in the second coupler, and a generated low coherence interference signal is received by the signal acquisition and processing system.
Furthermore, the first optical fiber cable, the second optical fiber cable and the third optical fiber cable are all armored optical fiber cables, and each armored optical fiber cable is composed of an inner bare optical fiber and an outer-layer-wrapped PVC tight wrapping layer.
According to another aspect of the application, a method for monitoring deep settlement of a soil body behind a shield tunnel wall is provided, and the method adopts the system for monitoring deep settlement of the soil body behind the shield tunnel wall, and comprises the following steps:
step 1: installing a data acquisition device;
step 2: fixing the data acquisition device;
and step 3: the method for collecting and processing the settlement monitoring data specifically comprises the following steps:
step 301: connecting the first optical fiber cable with a data processing system to form a monitoring system for soil deep settlement;
step 302: measuring signals of the low coherence interference optical fiber sensor, scanning the LCI displacement sensor, and waiting for the interference signal spectrum and the optical path difference demodulation result to tend to be stable;
step 303: monitoring and recording the data and calculating the deep settlement of the soil body above the tunnel.
Further, step 1 specifically includes:
step 101: drilling a reserved grouting hole of the tunnel to a specified position by using a micro drilling machine;
step 102: printing an LCI displacement meter by adopting a 3D printing technology, checking the monitoring availability of the displacement meter, and combining a PVC pipe, a lantern ring, a filter screen, a first micro grouting pipe, a second micro grouting pipe and the LCI displacement meter according to preset positions;
step 103: and (3) inserting the combined body in the step 102 into the hole, wrapping the filter screen by the lantern ring to be in a horizontal state, and fixing the position of the LCI displacement meter to be in a vertical downward state.
Further, step 2 specifically includes:
step 201: grouting the first miniature grouting pipe in the upward direction to quickly form a grouting block above the filter screen and fix the anchor head, and further fixing one end of the LCI displacement meter;
step 202: waiting for the initial setting of the upper grouting block, and reserving and protecting the first optical fiber cable outside the hole;
step 203: and grouting the second miniature grouting pipe facing downwards, enabling the LCI displacement meter to be tightly connected with the surrounding soil body through grouting, monitoring the settlement displacement of the soil body by cooperative motion, then filling the hole until the hole cannot be filled, wherein the PVC pipe is pulled out while grouting is carried out in the grouting process, the pipe pulling speed is controlled, and the hole collapse is avoided.
Furthermore, the first micro grouting pipe uses quick-setting grout which comprises cement grout and water glass with the amount of 2% -3%, the second micro grouting pipe uses waterproof grout with the strength similar to that of a soil body and comprises bentonite, cement and water, and the mass ratio of the bentonite to the cement to the water is (6-7): (2-3): 12-16).
Compared with the prior art, the application has the advantages that:
1. the method is novel, breaks through the dilemma that the drilling measurement cannot be carried out under the condition that the shield tunnel segment is sealed, designs the monitoring method for the deep settlement of the soil body behind the nondestructive shield tunnel wall, and enables the monitoring process to be more in line with the actual condition.
2. The displacement meter is improved, so that the monitoring result is more accurate and reliable, the optical fiber sensor based on the low-coherence interference technology has the advantages of high monitoring precision, strong anti-electromagnetic interference and more stable monitoring process, is suitable for long-term monitoring of the tunnel, and can be applied to the actual conditions of engineering.
3. By introducing the optical fiber sensor, the automatic acquisition of data can be realized, the monitoring efficiency is greatly improved, the engineering condition can be uninterruptedly monitored, the safety of field monitoring is improved, and the reliable guarantee is provided for engineering.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:
fig. 1 is a schematic diagram illustrating a data acquisition device in a shield tunnel wall back soil deep settlement monitoring system according to an embodiment of the present application;
FIG. 2 shows an LCI sensor layout according to one embodiment of the present application;
FIG. 3 illustrates a schematic view of a data acquisition device being inserted into a hole according to one embodiment of the present application;
FIG. 4 illustrates a schematic view of a first upwardly oriented micro-grouting pipe being grouted to form a grouting block according to an embodiment of the present application;
FIG. 5 illustrates a pull out PVC pipe schematic diagram according to one embodiment of the present application;
FIG. 6 is a schematic diagram illustrating a second micro-grouting tube in a downward direction, filling a hole, according to an embodiment of the present application;
figure 7 illustrates a perspective view of a deep soil settlement monitoring system according to one embodiment of the present application;
FIG. 8 illustrates a cross-sectional view of a fiber optic cable according to one embodiment of the present application;
figure 9 shows a flow chart of a soil settlement monitoring method according to one embodiment of the present application.
The same or similar reference numbers in the drawings denote the same or similar parts, including:
the device comprises an anchor head 1, an LCI displacement meter 2, a PVC pipe 3, a first optical fiber cable 41, a filter screen 5, a lantern ring 6, a first micro grouting pipe 7, a second micro grouting pipe 8, an LCI optical fiber sensor 9, a 3D printed cylindrical body 10, a pipe piece 11, a reserved grouting hole 12, quick setting grout 13, waterproof grout 14 with the strength close to that of soil, soil 15 to be detected, a broadband light source 16, a signal acquisition and processing system 17, a first coupler 18, a second coupler 19, a second optical fiber cable 42, a third optical fiber cable 43, an optical fiber 20 with the flattened tail end, a reflector 21, an optical mobile scanning platform 22, a reference arm 23, a bare fiber 24 and a PVC tight cladding layer 25.
Detailed Description
The present application is described in further detail below with reference to the attached figures.
Fig. 1 shows a perspective view of a data acquisition device in a monitoring system for deep settlement of soil behind a shield tunnel wall.
As shown in fig. 1, the data acquisition device comprises an anchor head, an LCI displacement meter, a PVC pipe, a first optical fiber cable, a filter screen, a lantern ring, a first micro grouting pipe and a second micro grouting pipe, wherein the LCI displacement meter is arranged in the PVC pipe, the upper end of the LCI displacement meter is rigidly connected with the anchor head, the lower end of the LCI displacement meter is connected with the data processing system through the first optical fiber cable, the anchor head extends into the PVC pipe and is inserted into the in-situ soil body, the lantern ring is sleeved on the PVC pipe, the filter screen is embedded between the lantern ring, and the first micro grouting pipe and the second micro grouting pipe are bundled and arranged in the PVC pipe.
In some embodiments, the filter screen is made of a novel polyurethane material, the pore size of the filter screen is set according to the grout, the principle of blocking most of the grout from passing is followed, and the anchor head and the micro grouting pipe are allowed to be hung and fixed on the filter screen.
In some embodiments, the first micro-grouting pipe is positioned above the filter screen, the grouting hole is upward, the second micro-grouting pipe is fixed on the filter screen, and the grouting opening is downward.
In some embodiments, an LCI displacement meter includes an LCI fiber optic sensor and a 3D printed cylinder, the LCI fiber optic sensor disposed at a central axis of the cylinder.
In some embodiments, a data processing system comprises: the LCI displacement meter comprises a broadband light source, a second optical fiber cable, a third optical fiber cable, a first coupler, a second coupler, an optical mobile scanning platform, a tail-end-cut optical fiber and a signal acquisition and processing system, wherein a signal arm of an LCI optical fiber sensor in the LCI displacement meter is connected with the broadband light source through the first optical fiber cable, a reference arm of the LCI optical fiber sensor is connected with the signal acquisition and processing system through the third optical fiber cable, the signal arm of the LCI optical fiber sensor is provided with the first coupler, the reference arm of the LCI optical fiber sensor is provided with the second coupler, the first coupler is connected with the second coupler through the second optical fiber cable, the second coupler is connected with the tail-end-cut optical fiber, and the reference arm of the LCI optical fiber sensor is matched with a reflector on the optical mobile scanning platform;
light emitted by the broadband light source passes through the first coupler along the first optical fiber cable and then reaches the LCI optical fiber sensor, the light enters the LCI optical fiber sensor and then is reflected, the light passes through the first coupler and then reaches the second coupler, the light is divided into two paths, the two paths of light are respectively reflected by the optical fiber with the flattened tail end and the reflector on the optical moving platform, the two paths of reflected light are converged and interfered in the second coupler, and a generated low coherence interference signal is received by the signal acquisition and processing system.
In some embodiments, the first optical fiber cable, the second optical fiber cable and the third optical fiber cable are armored optical fiber cables, and the armored optical fiber cables are composed of an inner bare optical fiber and an outer PVC tight cladding layer.
Specifically, as shown in fig. 1 and 7, the principle of the monitoring system for deep settlement of soil above a tunnel based on the low coherence interference technology is as follows: light emitted by the broadband light source 16 passes through the coupler I18 on the broadband light source along the first optical fiber cable 41 and then is located in the LCI displacement meter 2 in the soil above the tunnel, the inner LCI optical fiber sensor 9 can be subjected to tensile and compression deformation due to deep sedimentation of the soil above the tunnel, the inner optical path changes, when the optical path difference of the light reflected by the LCI displacement meter 2 and the reference arm 23 is lower than the minimum coherent optical path, light interference occurs, and a low-coherent interference signal generated in the process is received and processed by the signal acquisition and processing system 17.
A monitoring system and a method for soil deep settlement above a tunnel based on low coherence interference technology are disclosed, wherein an optical fiber cable is protected by armored optical fibers, and the armored optical fiber cable consists of an inner bare optical fiber 24 and an outer PVC tight cladding layer 25 (diameter is 1.8mm), as shown in figure 8.
A monitoring device for soil deep settlement behind a nondestructive shield tunnel wall is characterized by mainly comprising an anchor head 1, an LCI displacement meter 2, a PVC pipe 3, a filter screen 5, a lantern ring 6 and two micro grouting pipes (a micro grouting pipe I7 and a micro grouting pipe 8). Wherein the diameter of the PVC pipe 3 is smaller than the diameter of the reserved grouting hole 12, and two micro grouting pipes and an LCI displacement meter 2 can be placed in the PVC pipe 3; the middle of the lantern ring 6 is embedded with the filter screen 5, and the lantern ring 6 can be sleeved on the PVC pipe 3; the aperture of the filter screen 5 should block most of slurry from passing through, the anchor head 1 and the micro grouting pipe are allowed to be suspended and fixed on the filter screen, and the filter screen 5 is made of a novel polyurethane material; in the two micro grouting pipes, a first micro grouting pipe 7 is positioned above the filter screen 5, a grouting hole is upward, a second micro grouting hole 8 is fixed on the filter screen 5, then a grouting opening is downward, the two micro grouting pipes are bound together inside the PVC pipe 2, and the positions of the two micro grouting pipes are fixed in the grouting process, so that the LCI displacement meter 2 is prevented from being disturbed; the anchor head 1 as described above, wherein it extends into the PVC pipe 3 and is inserted into the in situ soil; the LCI displacement meter 2 as described above is characterized in that the upper end thereof is rigidly connected to the anchor head 1, and the LCI fiber sensor 9 and the 3D printed cylinder 10 are formed as a part, and the LCI fiber sensor 9 is arranged at the central axis of the 3D printed cylinder 10. The specific situation is shown in fig. 2.
The monitoring method for deep soil settlement in the scheme adopts the monitoring system for deep soil settlement, and comprises the following steps:
step 1: installing a data acquisition device;
step 2: fixing the data acquisition device;
and step 3: the method for collecting and processing the settlement monitoring data specifically comprises the following steps:
step 301: connecting the first optical fiber cable with a data processing system to form a monitoring system for soil deep settlement;
step 302: measuring signals of the low coherence interference optical fiber sensor, scanning the LCI displacement sensor, and waiting for the interference signal spectrum and the optical path difference demodulation result to tend to be stable;
step 303: monitoring and recording the data and calculating the deep settlement of the soil body above the tunnel.
In some embodiments, step 1 specifically includes:
step 101: drilling a reserved grouting hole of the tunnel to a specified position by using a micro drilling machine;
step 102: printing an LCI displacement meter by adopting a 3D printing technology, checking the monitoring availability of the displacement meter, and combining a PVC pipe, a lantern ring, a filter screen, a first micro grouting pipe, a second micro grouting pipe and the LCI displacement meter according to preset positions;
step 103: and (3) inserting the combined body in the step 102 into the hole, wrapping the filter screen by the lantern ring to be in a horizontal state, and fixing the position of the LCI displacement meter to be in a vertical downward state.
In some embodiments, step 2 specifically includes:
step 201: grouting the first miniature grouting pipe in the upward direction to quickly form a grouting block above the filter screen and fix the anchor head, and further fixing one end of the LCI displacement meter;
step 202: after the grouting block above is initially set, reserving the first optical fiber cable outside the hole;
step 203: and grouting the second miniature grouting pipe facing downwards, enabling the LCI displacement meter to be tightly connected with the surrounding soil body through grouting, monitoring the settlement displacement of the soil body by cooperative motion, then filling the hole until the hole cannot be filled, wherein the PVC pipe is pulled out while grouting is carried out in the grouting process, the pipe pulling speed is controlled, and the hole collapse is avoided.
In some embodiments, the first micro grouting pipe uses quick setting grout which comprises cement grout and water glass with the amount of 2% -3%, the second micro grouting pipe uses waterproof grout with the strength similar to that of soil body and consists of bentonite, cement and water, and the mass ratio of the bentonite to the cement to the water is (6-7) to (2-3) to (12-16).
A method for monitoring the deep settlement of soil mass behind the wall of a nondestructive shield tunnel, the flow chart is shown in figure 9,
the method comprises the following steps:
step one, installation of a settlement monitoring device:
step 101, drilling a reserved grouting hole 12 of a tunnel to a specified position by using a micro drilling machine, wherein a small amount of water seepage is allowed in the process;
102, printing the LCI displacement meter 2 by adopting a 3D printing technology, checking the monitoring availability of the displacement meter, and combining a PVC pipe 3, a lantern ring 6, a filter screen, a micro grouting pipe (comprising a micro grouting pipe I7 and a micro grouting pipe II 8) and an LCI displacement meter 9 together according to a certain position;
step 103, inserting the combined body in the step 102 into the hole, wherein the filter screen 5 is in a horizontal state under the wrapping of the lantern ring 6, and the LCI displacement meter 2 is fixed in position and in a vertically downward state, as shown in FIG. 3;
step two, fixing the settlement monitoring device:
step 201, grouting the upward-oriented micro grouting pipe I7, and using quick setting grout 13, wherein the quick setting grout is mainly composed of cement grout and water glass with the amount of 2% -3%, so that a grouting block is quickly formed above the filter screen 5 and the anchor head 1 is fixed, and then one end of the LCI displacement meter 2 is fixed, as shown in FIG. 4;
step 202, after the initial setting of the grouting block is estimated for a period of time, reserving the optical fiber cable 41 outside the hole, as shown in fig. 5;
step 203, grouting the second miniature grouting pipe 8 facing downwards, and using waterproof slurry with the strength similar to that of a soil body, wherein the waterproof slurry consists of bentonite, cement and water, and the mass ratio of the bentonite to the cement to the water is (6-7): (2-3), (12-16), preferably 5:2:13, in order to tightly connect the LCI displacement meter 2 with the surrounding soil body through grouting, move cooperatively, monitor the settlement displacement of the soil body, fill the hole until the hole can not be filled, wherein the PVC pipe 3 is pulled out while grouting in the grouting process, and the pipe pulling speed is controlled to ensure that the hole does not collapse, as shown in FIG. 6;
step three, settlement monitoring and data processing:
step 301, connecting the optical fiber cable 41 with a data transmission and data processing part outside the drill hole to form a settlement displacement monitoring system;
step 302, performing signal debugging measurement by combining the low coherence interference optical fiber sensor and a corresponding software system, scanning the LCI displacement sensor 9, and waiting for the interference signal spectrum and the optical path difference demodulation result to tend to be stable;
and 303, monitoring, recording the data and combining a corresponding algorithm to obtain the deep settlement of the soil body above the tunnel.
During the monitoring process, great interference should be avoided so as not to cause instability of the optical fiber and influence the real monitoring result.
A monitoring method for soil deep settlement behind a nondestructive shield tunnel wall based on a low coherence interference technology has the following working principle:
when the LCI displacement meter 2 is deformed, the internal LCI fiber sensor 9 is strained. The light path wavelength inside the LCI optical fiber sensor 9 will change correspondingly if the optical path difference of the light reflected back by the LCI displacement meter 2 and the reference arm 23 is less than the minimum coherent optical path ScThen, light interference occurs. Under the condition, the LCI optical fiber sensor 9 generates tensile deformation deltaS () and corresponding change of the refractive index deltam () of the fiber core, and then the optical path difference deltaa between the LCI displacement meter 2 and the reference arm 23 can be obtained1The calculation formula is as follows:
Δa1＝m△S()+S△m() (a)
in the formula: for strain deformation, S represents the fiber length in the LCI displacement meter and m represents the core index.
The optical path length change of the optical fiber caused by the strain change of the LCI fiber sensor 9 can be expressed by the following equation:
ΔS()＝S (b)
the changes in the refractive index caused by the strain changes of the LCI fiber sensor 9 are respectively expressed by the following equations:
wherein μ is Poisson's ratio, q11And q is12The Pockel constant of the fiber.
Combining the formulas (a), (b) and (c) can obtain the following formula for calculating the optical path difference:
the detailed parameters of a standard single mode fiber are as follows: q. q.s11＝0.12，q12＝0.27，μ＝0.15，m＝1.46。
The relationship between the optical path difference and the strain is thus obtained as follows:
Δa1＝1.19S (e)
this can give the strain:
the displacement can then be found as:
it will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is obvious that the word "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. A plurality of units or means recited in the apparatus claims may also be implemented by one unit or means in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.
Claims (8)
1. A monitoring system for deep settlement of soil behind a shield tunnel wall is characterized by comprising a data acquisition device and a data processing system; the data acquisition device comprises an anchor head, an LCI displacement meter, a PVC pipe, a first optical fiber cable, a filter screen, a lantern ring, a first micro grouting pipe and a second micro grouting pipe, wherein the LCI displacement meter is arranged in the PVC pipe, the upper end of the LCI displacement meter is rigidly connected with the anchor head, the lower end of the LCI displacement meter is connected with the data processing system through the first optical fiber cable, the anchor head extends into the PVC pipe and is inserted into an in-situ soil body, the lantern ring is sleeved on the PVC pipe, the filter screen is embedded in the lantern ring, and the first micro grouting pipe and the second micro grouting pipe are bound and arranged in the PVC pipe; the filter screen is made of polyurethane materials, the aperture size of the filter screen is set according to the grout, the principle of blocking most of the grout from passing is followed, and the anchor head and the micro grouting pipe are allowed to be suspended and fixed on the filter screen; the first miniature grouting pipe is positioned above the filter screen, the direction of a grouting hole faces upwards, the second miniature grouting pipe is fixed on the filter screen, and the direction of a grouting opening faces downwards.
2. The system of claim 1, wherein the LCI displacement meter includes an LCI fiber sensor and a 3D printed cylinder, the LCI fiber sensor being disposed at a central axis of the cylinder.
3. The system for monitoring deep settlement of earth behind a shield tunnel wall of claim 2, wherein the data processing system comprises: the LCI displacement meter comprises a broadband light source, a second optical fiber cable, a third optical fiber cable, a first coupler, a second coupler, an optical mobile scanning platform, a tail-end-cut optical fiber and a signal acquisition and processing system, wherein a signal arm of an LCI optical fiber sensor in the LCI displacement meter is connected with the broadband light source through the first optical fiber cable, a reference arm of the LCI optical fiber sensor is connected with the signal acquisition and processing system through the third optical fiber cable, the signal arm of the LCI optical fiber sensor is provided with the first coupler, the reference arm of the LCI optical fiber sensor is provided with the second coupler, the first coupler is connected with the second coupler through the second optical fiber cable, the second coupler is connected with the tail-end-cut optical fiber, and the reference arm of the LCI optical fiber sensor is matched with a reflector on the optical mobile scanning platform; light emitted by the broadband light source passes through the first coupler along the first optical fiber cable and then reaches the LCI optical fiber sensor, the light enters the LCI optical fiber sensor and then is reflected, the light passes through the first coupler and then reaches the second coupler, the light is divided into two paths, the two paths of light are respectively reflected by the optical fiber with the flattened tail end and the reflector on the optical moving platform, the two paths of reflected light are converged and interfered in the second coupler, and a generated low coherence interference signal is received by the signal acquisition and processing system.
4. The system for monitoring deep settlement of soil behind the wall of the shield tunnel according to claim 3, wherein the first optical fiber cable, the second optical fiber cable and the third optical fiber cable are armored optical fiber cables, and the armored optical fiber cables are composed of an inner bare optical fiber and an outer PVC tight-clad layer.
5. A method for monitoring deep settlement of soil behind a shield tunnel wall, which adopts the system for monitoring deep settlement of soil behind a shield tunnel wall as claimed in any one of claims 1 to 4, and is characterized in that the method comprises the following steps:
step 1: installing a data acquisition device;
step 2: fixing the data acquisition device;
and step 3: the method for collecting and processing the settlement monitoring data specifically comprises the following steps:
step 301: connecting the first optical fiber cable with a data processing system to form a monitoring system for soil deep settlement;
step 302: measuring signals of the low coherence interference optical fiber sensor, scanning the LCI displacement sensor, and waiting for the interference signal spectrum and the optical path difference demodulation result to tend to be stable;
step 303: monitoring and recording the data and calculating the deep settlement of the soil body above the tunnel.
6. The method for monitoring deep settlement of soil behind the wall of the shield tunnel according to claim 5, wherein the step 1 specifically comprises:
step 101: drilling a reserved grouting hole of the tunnel to a specified position by using a micro drilling machine;
step 102: printing an LCI displacement meter by adopting a 3D printing technology, checking the monitoring availability of the displacement meter, and combining a PVC pipe, a lantern ring, a filter screen, a first micro grouting pipe, a second micro grouting pipe and the LCI displacement meter according to preset positions;
step 103: and (3) inserting the combined body in the step 102 into the hole, wrapping the filter screen by the lantern ring to be in a horizontal state, and fixing the position of the LCI displacement meter to be in a vertical downward state.
7. The method for monitoring deep settlement of soil behind the wall of the shield tunnel according to claim 6, wherein the step 2 specifically comprises:
step 201: grouting the first miniature grouting pipe in the upward direction to quickly form a grouting block above the filter screen and fix the anchor head, and further fixing one end of the LCI displacement meter;
step 202: waiting for the initial setting of the upper grouting block, and reserving and protecting the first optical fiber cable outside the hole;
step 203: and grouting the second miniature grouting pipe facing downwards, enabling the LCI displacement meter to be tightly connected with the surrounding soil body through grouting, monitoring the settlement displacement of the soil body by cooperative motion, then filling the hole until the hole cannot be filled, wherein the PVC pipe is pulled out while grouting is carried out in the grouting process, the pipe pulling speed is controlled, and the hole collapse is avoided.
8. The method for monitoring the deep settlement of the soil behind the shield tunnel wall as recited in claim 7, wherein the first micro grouting pipe uses quick setting grout which comprises cement grout and water glass with the amount of 2% -3%, the second micro grouting pipe uses waterproof grout with the strength similar to that of the soil and comprises bentonite, cement and water, and the mass ratio of the bentonite to the cement to the water is (6-7): 2-3): 12-16.
Priority Applications (1)
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| CN103290827A (en) * | 2013-06-17 | 2013-09-11 | 中国水利水电第十四工程局有限公司 | Mounting, burying and grouting method for multi-point displacement meter |
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| CN103290827A (en) * | 2013-06-17 | 2013-09-11 | 中国水利水电第十四工程局有限公司 | Mounting, burying and grouting method for multi-point displacement meter |
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