CN111395348B - Method for controlling upward floating of existing tunnel striding on foundation pit by adopting hydraulic servo system - Google Patents
Method for controlling upward floating of existing tunnel striding on foundation pit by adopting hydraulic servo system Download PDFInfo
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- CN111395348B CN111395348B CN202010106538.6A CN202010106538A CN111395348B CN 111395348 B CN111395348 B CN 111395348B CN 202010106538 A CN202010106538 A CN 202010106538A CN 111395348 B CN111395348 B CN 111395348B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
- E02D31/10—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against soil pressure or hydraulic pressure
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/74—Means for anchoring structural elements or bulkheads
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Abstract
The invention relates to a construction method of urban underground engineering, and discloses a floating deformation control method for an existing tunnel striding on a foundation pit by adopting a hydraulic servo system, wherein the method comprises the following construction steps: a, arranging an in-tunnel monitoring system (22); b, constructing a foundation pit enclosure structure and a dewatering well; c, constructing an anti-pulling pile, or constructing an anti-pulling anchor rod (17) or an anti-pulling anchor cable; d, excavating the foundation pit to a specified elevation in a layered and sectional manner or in a vertical shaft manner; e, constructing an uplift pile buffer layer (10) made of foam or rubber and a PVC protection pipe (9) of uplift pile reinforcing steel bars, or constructing a PVC protection pipe of uplift anchor rods or uplift anchor cables; f, constructing a reinforced concrete anti-floating plate (14); g, installing a hydraulic servo control system (16); h, repeating the step d to the step g, and adjusting the output value of the hydraulic servo control system (16) according to the tunnel deformation value in the whole process; and i, locking the uplift pile in sections or locking the uplift anchor rod or the uplift anchor cable in sections, and constructing a main body structure. The invention can control the deformation of the tunnel in real time by regions.
Description
Technical Field
The invention relates to a construction method of urban underground engineering, in particular to a floating control method for an existing tunnel striding on a foundation pit by adopting a hydraulic servo system.
Background
With the increase of urban rail transit operation mileage and the further development of underground space, more and more cases are carried out on excavating and unloading large-area foundation pits above the urban operation subway shield tunnel. Excavation of the foundation pit inevitably causes the bottom of the pit and the tunnel lying down to generate uplift deformation, and when the operation tunnel is deformed too much, the segment is damaged, water leakage is caused, and the tunnel operation safety is influenced. 14 domestic foundation pit engineering examples are collected in a text of 'actual measurement and analysis of influence of foundation pit excavation on an existing shield tunnel below' published by 'geotechnical' in 2013, the actual measurement data is statistically analyzed, and the result shows that 64% of tunnel floating deformation values exceed an alarm value by 10mm, which indicates that the deformation of a lower lying shield tunnel caused by unloading of foundation pit excavation cannot be ignored.
Liu Tuo Qiang, Dong Tianjun, Zhang Longyun, equal to 2019, in the application research of the uplift pile combined anti-floating plate in the control of the uplift of the horizontal subway tunnel under the foundation pit, which is published by Guangdong building materials, the text introduces that the uplift pile combined anti-floating plate forms a whole to inhibit the vertical uplift of the tunnel. However, the anti-floating plate can be poured only after the foundation pit needs to be excavated to the bottom, so that the tunnel generates certain floating deformation before the anti-floating plate is poured. The anti-floating plate is rigidly connected with the anti-pulling pile, and the anti-pulling pile can exert the stress action only by generating larger upward pulling deformation. Therefore, after the anti-floating plate is poured, the floating deformation amount of the tunnel before pouring cannot be reduced, and the limiting effect of the anti-floating pile and the anti-floating plate system can be exerted only by further increasing the deformation of the tunnel to a certain degree, so that the deformation of the tunnel exceeds a control value, and the anti-floating plate and the anti-floating pile are still stressed less and cannot fully exert the effect.
Therefore, it is an urgent technical problem to be solved by those skilled in the art to provide a construction technique capable of controlling deformation of a tunnel induced by excavation of a foundation pit.
Disclosure of Invention
The invention aims to solve the technical problem of providing a floating control method for an existing tunnel striding on a foundation pit by adopting a hydraulic servo system, which can control the tunnel deformation in a regional and real-time manner.
In order to achieve the aim, the invention provides a floating control method for an existing tunnel spanned on a foundation pit by adopting a hydraulic servo system, which comprises the following construction steps: a, arranging a monitoring system in a tunnel; b, constructing a foundation pit enclosure structure and a dewatering well; c, constructing an anti-pulling pile, or constructing an anti-pulling anchor rod or an anti-pulling anchor cable; d, excavating the foundation pit to a specified elevation in a layered and sectional manner or in a vertical shaft manner; e, constructing a foam or rubber uplift pile buffer layer and a PVC protection pipe of an uplift pile reinforcing steel bar, or constructing a PVC protection pipe of the uplift anchor rod or the uplift anchor cable; f, constructing a reinforced concrete anti-floating plate; g, installing a hydraulic servo control system; h, repeating the step d to the step g, and adjusting the output value of the hydraulic servo control system according to the tunnel deformation value in the whole process; and i, locking the uplift pile in sections or locking the uplift anchor rod or the uplift anchor cable in sections, and constructing a main body structure.
Preferably, in step c, the minimum distance between the uplift pile and the tunnel is not less than 1.5m, the pile bottom of the uplift pile is located at a position which is one time of the tunnel diameter from the bottom of the tunnel, the uplift force of the uplift pile is not less than 1.5 times of the earth covering weight, and the construction of the uplift pile is implemented by adopting a full-casing rotary drilling machine.
Preferably, in the step c, when the rock formation below the tunnel meets the construction requirements, an anti-pulling anchor rod or an anti-pulling anchor cable is selected, wherein an anchoring section of the anti-pulling anchor rod or the anti-pulling anchor cable is embedded into the rock formation below the tunnel, the minimum distance between the anti-pulling anchor rod or the anti-pulling anchor cable and the tunnel is not less than 1.5m, the anchoring section of the anti-pulling anchor rod or the anti-pulling anchor cable is positioned below one time of the tunnel hole diameter at the bottom of the tunnel, and the anti-pulling force of the anchoring section is not less than 1.5 times of the upper soil covering weight.
Preferably, in the step d, the excavation of the foundation pit adopts a layered and sectional excavation mode, or a mode of jumping excavation by a vertical shaft and constructing a supporting structure, so as to control the deformation of the tunnel and ensure the self-stability of the foundation pit.
Preferably, in the step e, the thickness of the foam or the rubber of the uplift pile buffer layer is estimated according to 2 times of the pit bottom resilience after excavation and unloading of the foundation pit, and the minimum thickness is not less than 5 cm.
Preferably, in step e, the PVC protection pipe for the uplift pile steel bar or the PVC protection pipe for the uplift anchor rod or the uplift anchor cable can prevent the uplift pile steel bar or the uplift anchor rod or the uplift anchor cable from being cemented with the anti-floating plate, so as to ensure that the uplift pile steel bar or the uplift anchor rod or the uplift anchor cable and the anti-floating plate are stressed independently.
Preferably, in step f, the anti-floating plate is a cast-in-place reinforced concrete anti-floating plate or a precast slab, and is formed with a groove for installing a steel plate or an anchor, and the depth of the groove is matched with a steel bar anchor head for fixing the steel plate or the anchor.
Preferably, in the step h, when the output value of the servo system is adjusted according to the tunnel deformation value, the amplitude of each adjustment is controlled, the next adjustment is performed after the tunnel is deformed stably, and in the adjustment process, the tunnel overburden pressure is not greater than the tunnel overburden weight before excavation, and the tunnel is prevented from settlement.
Preferably, in step i, when a main body structure is constructed in an anti-floating plate coverage area, the anti-pulling piles or the anti-pulling anchor rods or the anti-pulling anchor cables in the construction area are locked in advance, a hydraulic servo unit controlled by the hydraulic servo control system is removed, and a tunnel deformation value is monitored in real time in the locking process, wherein the locking value of the anti-pulling piles or the anti-pulling anchor rods or the anti-pulling anchor cables is not larger than the weight of soil covered on the tunnel before excavation, and the tunnel is not settled.
Through the technical scheme, the invention has the following beneficial effects:
the invention adopts a mode of combining a hydraulic servo system and an uplift pile or an uplift anchor rod (anchor cable) to control the uplift deformation of a lower horizontal existing tunnel caused by foundation pit excavation, utilizes the accurate control of the hydraulic servo control system on output pressure to actively compensate the overburden soil pressure of the tunnel reduced by the unloading of the foundation pit excavation, and can fully exert the bearing capacity of the uplift pile or the uplift anchor rod, thereby effectively reducing the uplift deformation of the tunnel during the foundation pit excavation in a regional, real-time and safe operation of the tunnel in the construction process.
Additional features and more prominent advantages of the invention will be set forth in the detailed description which follows.
Drawings
FIG. 1 is a construction flow chart of a floating control method for an existing tunnel spanned on a foundation pit by adopting a hydraulic servo system;
FIG. 2 is a schematic diagram of a parallel relative position relationship between a tunnel and a foundation pit according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the intersection relative position relationship between the tunnel and the foundation pit according to another embodiment of the present invention;
fig. 4 is a schematic view of a shaft excavation uplift pile system in one embodiment of the invention;
fig. 5 is a schematic view of a segmental excavation uplift pile system in another embodiment of the invention;
FIG. 6 is a schematic plan view of a uplift pile system of the hydraulic servo control system in one embodiment of the invention;
fig. 7 is a detail view of a uplift pile system in one embodiment of the invention;
fig. 8 is a detail view of the final state of the uplift pile system in one embodiment of the invention;
fig. 9 is a schematic view of a uplift anchor (cable) system for shaft excavation in another embodiment of the invention;
fig. 10 is a schematic view of a segmental excavation uplift anchor rod (cable) system in another embodiment of the invention;
FIG. 11 is a schematic plan view of a hydraulic servo control system uplift anchor rod (cable) system in another embodiment of the invention;
FIG. 12 is a detail view of a uplift anchor (cable) system in another embodiment of the invention;
fig. 13 is a detail view of the final state of the uplift anchor (cable) system in another embodiment of the invention.
Description of the reference numerals
1 foundation pit sideline 2 tunnel sidelines
3 tunnel center line 4 ground
5 tunnel 6 uplift pile
7 anti-floating pile reinforcing bar 8 supporting construction
9 PVC protection tube 10 buffer layer
11 steel bar anchor head 12 steel plate
13 hydraulic servo unit 14 anti-floating plate
15 structure bottom plate 16 hydraulic servo control system
17 anti-pulling anchor rod 18 anchor nut
19 ground tackle 20 tunnel monitoring point
21 line 22 monitoring system
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; either directly or indirectly through intervening media, either internally or in any combination thereof. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
As shown in fig. 1 to 13, the method for controlling upward floating of an existing tunnel over a foundation pit by using a hydraulic servo system according to the basic embodiment of the present invention includes the following steps:
a, arranging an in-tunnel monitoring system 22;
b, constructing a foundation pit enclosure structure and a dewatering well;
c, constructing an uplift pile 6, or constructing an uplift anchor rod 17 or an uplift anchor cable;
d, excavating the foundation pit to a specified elevation in a layered and sectional manner or in a vertical shaft manner;
e, constructing a foam or rubber uplift pile buffer layer 10 and a PVC protection pipe 9 of the uplift pile reinforcing steel bar 7, or constructing the PVC protection pipe 9 of the uplift anchor rod or the uplift anchor cable, wherein the buffer layer 10 is formed by foam plastics or rubber;
f, constructing a reinforced concrete anti-floating plate 14;
g, installing a hydraulic servo control system 16;
h, repeating the step d to the step g, and adjusting the output value of the hydraulic servo control system 16 according to the tunnel deformation value in the whole process;
and i, locking the uplift pile 6 in a subsection mode or locking the uplift anchor rod 17 or the uplift anchor cable in a subsection mode, and constructing a main body structure.
Specifically, when an uplift pile system is applied, referring to fig. 7, a buffer layer 10 is formed at the top of an uplift pile 6, uplift pile steel bars 7 extending out of the top of the uplift pile 6 sequentially pass through the buffer layer 10, a PVC protection pipe 9 and two steel plates 12, the PVC protection pipe 9 penetrates through an uplift plate 14, the uplift pile steel bars 7 are further sequentially sleeved with two steel bar anchor heads 11, the two steel bar anchor heads 11 are in one-to-one correspondence with the two steel plates 12, each steel bar anchor head 11 is respectively positioned above the corresponding steel plate 12, and a hydraulic servo unit 13 is installed between the two steel plates 12; in the process of adjusting the tunnel deformation value, the steel bar anchor head 11 positioned at the lower part is unlocked, and the steel bar anchor head 11 positioned at the upper part is locked; when the tunnel deformation value is reduced to be less than 10mm and the tunnel 5 is ensured not to be settled, the reinforcing steel bar anchor head 11 at the lower part can be locked, the reinforcing steel bar anchor head 11 at the upper part, the steel plate 12 and the hydraulic servo unit 13 are removed, the reinforcing steel bars 7 of the uplift pile are cut off to the top of the uplift plate 14, and finally the main structure is constructed in the coverage area of the uplift plate 14, for example, fig. 8 shows a specific embodiment of the structural bottom plate 9 which constructs the main structure in the coverage area of the uplift plate 14;
the thickness of the buffer layer 10 above the uplift pile 6 is estimated according to 2 times of the rebound quantity of the foundation pit excavation unloading pit bottom, and the requirement is not less than 5 cm.
When the uplift anchor rod system is applied, referring to fig. 12, an anchor rod extending out of the top of the uplift anchor rod 17 sequentially penetrates through a PVC protection pipe 9 and 2 steel plates 12, the PVC protection pipe 9 penetrates through an anti-floating plate 14, an anchor nut 18 and a steel bar anchor head 11 are further sequentially sleeved in the anchor rod, the anchor nut 18 corresponds to the lower steel plate 12 and is positioned above the steel plate 12, the steel bar anchor head 11 corresponds to the upper steel plate 12 and is positioned above the steel plate 12, and a hydraulic servo unit 13 is arranged between the upper steel plate 12 and the lower steel plate 12; in the process of adjusting the tunnel deformation value, the anchor nut 18 is unlocked, and the steel bar anchor head 11 is locked; when the tunnel deformation value is reduced to be below 10mm and the tunnel 5 is ensured not to be settled, the anchor nuts 18 can be locked, the steel bar anchor heads 11, the steel plates 12 positioned above the steel bar anchor heads and the hydraulic servo units 13 are removed, the anchors 19 are installed, the anchor rods are cut off to the top of the anti-floating plates 14, and finally the main structure is constructed in the coverage area of the anti-floating plates 14, for example, fig. 13 shows a specific embodiment of the structural bottom plate 9 for constructing the main structure in the coverage area of the anti-floating plates 14; of course, the uplift anchor rods 17 may also be uplift anchor cables.
Referring to fig. 6 or 11, a tunnel is a shield tunnel, a monitoring system 22 in the tunnel is arranged, the monitoring system is realized by using a measuring robot and professional monitoring software in a matched manner, a plurality of monitoring sections are arranged in an excavation range, each monitoring section is provided with four tunnel monitoring points 20, namely one tunnel top, one tunnel waist and one track bed, each tunnel monitoring point 20 is connected into the monitoring system 22 through a line 21, and the monitoring system 22 is connected into a hydraulic servo control system 16 through a line 21; according to the monitored tunnel deformation value, the hydraulic servo control system 16 accurately controls the output pressure of the hydraulic servo unit 13, and the uplift pile 6 is matched with the uplift plate 14 or the uplift anchor rod 17 is matched with the uplift plate 14, so that the tunnel uplift deformation during the excavation of the foundation pit is effectively reduced in a regional, real-time and effective mode, wherein a pressure monitor is arranged at a tunnel monitoring point 20, and the existing measuring robot and monitoring software programs are adopted by the measuring robot and professional monitoring software.
In the step e, the PVC protection pipe 9 for sleeving the uplift pile steel bar 7 or the PVC protection pipe 9 for the anchor rod (cable) should effectively prevent the uplift pile steel bar 7 or the anchor rod (cable) from being cemented with the anti-floating plate 14, so as to ensure that the uplift pile steel bar 7 or the anchor rod (cable) and the anti-floating plate 14 are stressed independently; that is, the PVC protection pipe 9 for reinforcing bars has a diameter greater than that of the uplift pile reinforcing bars 7 or the PVC protection pipe 9 for anchor rods.
Generally, the anti-floating plate 14 is a cast-in-place reinforced concrete anti-floating plate or a prefabricated plate, and a groove for installing the steel plate 12 or the anchorage 19 is reserved on the anti-floating plate 14, and the depth of the groove is matched with the height of the reinforced bar anchor head 11 or the anchorage 19 for fixing the steel plate 12.
It should be noted that, as can be seen from the above, in the process of controlling the upward floating deformation of the existing tunnel lying below caused by excavation of the foundation pit, by adopting the mode of combining the hydraulic servo control system 16 with the uplift pile 6 or the uplift anchor rod 17, the overlying soil pressure of the tunnel reduced due to unloading of the excavation of the foundation pit is actively compensated, and the bearing capacity of the uplift pile 6 or the uplift anchor rod 17 is fully exerted, so that the upward floating deformation of the tunnel during excavation of the foundation pit is effectively reduced in a regional manner, in real time, and the operation safety of the tunnel in the construction process is ensured; moreover, the hydraulic servo control system 16 adjusts the output value in real time according to the tunnel deformation value in the whole process, that is, the locking operation of the uplift pile 6 or the uplift anchor rod 17 can be performed after the tunnel deformation at a single foundation pit position is adjusted in place, or after the tunnel deformation at all the foundation pit positions is adjusted in place, or the uplift pile 6 or the uplift anchor rod 17 corresponding to the foundation pit positions is locked after the tunnel deformation at a part of the foundation pit positions is adjusted in place, and the specific operation can be selected according to the actual construction condition; before the uplift pile 6 or the uplift anchor rod 17 is locked, the output value of the hydraulic servo system 16 can be adjusted in real time according to the whole process of the tunnel deformation value. Wherein the designated elevation is a vertical distance from a point on the ground or building to a selected reference level in a construction design.
In a specific embodiment, referring to fig. 7, in step c, the minimum close distance between the uplift pile 6 and the tunnel 5 is not less than 1.5m, the minimum close distance is a horizontal distance between an edge of an outer contour of the uplift pile 6 on a side close to the tunnel 5 and the tunnel 5, a pile bottom of the uplift pile 6 is located below one-time hole diameter from the bottom of the tunnel 5, where "below one-time hole diameter" means that the pile bottom of the uplift pile 6 is one-time hole diameter from the bottom of the tunnel 5 or exceeds one-time hole diameter, and a bearing capacity of the uplift pile 6 is not less than 1.5 times of the upper covering weight.
Similarly, referring to fig. 12, in step c, if a better rock stratum is located below the tunnel 5, an uplift anchor rod 17 may be used, an anchoring section of the anchor rod is embedded into the rock stratum below the tunnel 5, a minimum short distance between the anchor rod and the tunnel 5 is not less than 1.5m, the minimum short distance is a horizontal distance between an edge of an outer contour of the anchor rod close to the tunnel 5 and the tunnel 5, the anchoring section of the anchor rod is located below one-time hole diameter at the bottom of the tunnel 5, the one-time hole diameter includes one-time hole diameter and exceeds one-time hole diameter, and a bearing capacity of the anchor rod is not less than 1.5 times of soil covering weight.
Referring to fig. 4, 5, 9 and 10, in step d, the foundation pit may be excavated in a layered and segmented manner, or in a manner that the vertical shaft is jumped and excavated and is applied as the supporting structure 8, so that the deformation of the tunnel may be well controlled and the stability of the foundation pit may be ensured.
Further, in the step h, when the output value of the hydraulic servo control system 16 is adjusted according to the tunnel deformation value, the adjusted amplitude value is not too large, the next adjustment is performed after the tunnel deformation is stable, and in the adjustment process, the pressure on the tunnel 5 is not greater than the weight of the earth on the tunnel 5 before excavation, and the tunnel 5 is not allowed to settle.
And in step i, when a main body structure is constructed in the anti-floating plate coverage area, the anti-pulling piles 6 or the anti-pulling anchor rods 17 in the construction area need to be locked in advance, the hydraulic servo units 13 need to be removed, the deformation value of the tunnel is monitored in real time in the locking process, the locking value of the anti-pulling piles 6 or the anti-pulling anchor rods 17 enables the pressure on the tunnel 5 to be not larger than the soil covering weight on the tunnel 5 before excavation, and the tunnel 5 is not allowed to be settled.
Example (b):
in order to better understand the technical scheme of the invention, the method for controlling the upward floating of the foundation pit crossing the existing tunnel by using the hydraulic servo system is described below by combining specific data.
Taking the case of covering a certain site with residual soil of granite (conglomerate clay), and completely weathered and strongly weathered coarse-grained granite lying downwards as an example, an underground continuous wall is used as a foundation pit enclosure structure, the size of the foundation pit is 100m multiplied by 40m, the ground 4 is used as a reference, the elevation of the bottom of the foundation pit is-13 m, and the underground water level is-2.000 m. The subway tunnel left side line that has opened the operation crouches down in this foundation ditch, and the positional relationship of foundation ditch and tunnel can refer to figure 2, and tunnel sideline 2 is parallel with tunnel central line 3 and foundation ditch sideline 1, and gets into the foundation ditch scope completely, and the external diameter of tunnel is 6m, and tunnel top elevation is 19m, and the distance of foundation ditch bottom and tunnel top is 6m promptly, and tunnel and foundation ditch collineation distance length reach 80 m.
Referring to fig. 6, a monitoring system 22 is arranged in a tunnel, the monitoring system is realized by matching a measuring robot with professional monitoring software, a plurality of monitoring sections are arranged in an excavation range, four tunnel monitoring points 20 are arranged on each monitoring section, namely, one tunnel top, one tunnel side waist and one track bed, each tunnel monitoring point 20 is connected into the monitoring system 22 through a line 21, and the monitoring system 22 is connected into a hydraulic servo control system 16 through the line 21.
Referring to fig. 7, the uplift pile 6 is a cast-in-place pile with a diameter of 1m, is arranged on two sides of the tunnel 5, and has a safety distance of 1.5m from the tunnel 5, the pile is empty from the top of the anti-floating plate 14 to the ground surface, and the pile is solid from 19m below the top of the anti-floating plate 14, namely, the pile extends into 6m below the bottom of the tunnel 5.
The bearing capacity of the uplift pile is not less than:
wherein: a. b is the plane size of the anti-floating plate of the excavation region; h is the excavation depth; gamma ray′The effective gravity of the soil in the excavated area is obtained; and n is the number of the uplift piles in the excavation area. The effective gravity is also called as floating gravity, the natural gravity of the soil taken out from the underground water level can be used as saturated gravity, when the soil is below the underground water level, the soil is subjected to the buoyancy action of water, the effective gravity of particles in unit soil volume is obtained, and the gravity of the particles in unit soil volume minus the buoyancy is called as the effective gravity of the soil.
Referring to fig. 4, in combination with site geological conditions, the engineering adopts a shaft jumping excavation mode to excavate a foundation pit, the foundation pit is divided into 11 shafts in a collinear range, the size of each shaft is 6m multiplied by 12m, and the excavation depth is 13 m.
Specifically, the size of each vertical shaft is 6m × 12m, the excavation depth is 13m, the soil layer in which the vertical shaft is located is granite residual soil (conglomerate cohesive soil), the heavy gamma is 17.9KN/m3, the ground water level is-2.000 m, two rows of anti-floating plates are arranged in each anti-floating plate, namely 4 anti-floating piles 6, and therefore the bearing capacity of the anti-floating piles 6 is as follows:
referring to fig. 7, the buffer layer 10 on the uplift pile 6 is made of foam plastic, and the thickness is 8cm according to 2 times of the rebound amount of the foundation pit excavation unloading pit bottom.
Referring to fig. 7, the diameter of the uplift pile steel bar 7 is 22mm, and in order to prevent the uplift pile steel bar 7 from being cemented with the anti-floating plate 14, the diameter of the PVC protection pipe 9 is 50mm, and after the uplift pile steel bar 7 is sleeved in, the pipe opening is immediately plugged by a sealing plug to prevent foreign matters and concrete from entering the pipeline.
Referring to fig. 7, the anti-floating plate 14 is a cast-in-place C30 reinforced concrete anti-floating plate, the plate thickness is 0.9m, a groove is reserved for installing the steel plate 12 during casting, and the height of the groove is 6 cm.
Referring to fig. 7, the steel plate 12 has a diameter of 1m and a thickness of 20mm, and is perforated according to the number of exposed bars of each uplift pile 6.
Referring to fig. 7, the subsequent steps of casting the anti-floating plate 14 are: cutting off the PVC protection pipe 9 to the bottom of the groove; installing the steel plate 12 located below; the steel bar anchor head 11 positioned at the lower part is sleeved (unlocked); installing a hydraulic servo unit 13; installing the steel plate 12 positioned above; and the steel bar anchor head 11 positioned above is sleeved (locked).
Referring to fig. 7, the number of hydraulic servo units 13 is determined by the number of anti-floating piles 6, and each anti-floating plate 14 corresponds to four hydraulic servo units 13. Each hydraulic servo unit 13 includes: a hydraulic jack; a hydraulic oil cylinder is matched; a pressure monitor; a front-end controller.
Referring to fig. 6, the pressure monitor detects the deformation of the tunnel, transmits data to the hydraulic servo control system 16, and the front-end controller is connected with the hydraulic servo control system 16 through a line 21, receives a working instruction sent by the hydraulic servo control system 16, is connected with the hydraulic cylinder through the line 21, controls the hydraulic cylinder to be started and closed according to the working instruction, and drives the hydraulic jack to work through the hydraulic cylinder.
Referring to fig. 4, the expression "repeating steps d to g and adjusting the output value of the hydraulic servo control system 16 according to the tunnel deformation value in the whole process" means: in the subsequent construction processes of subsequent excavation, pouring of the anti-floating plate 14, structural pouring and the like, the output value of the hydraulic servo control system 16 is adjusted in regions and in real time according to the real-time monitoring result of tunnel deformation, so that the earth covering pressure on the tunnel 5 is basically kept stable, and the floating deformation of the tunnel 5 is controlled.
Referring to fig. 8, the step of 'locking the uplift pile in sections and constructing the main structure' of the invention is as follows: locking a reinforcing steel bar anchor head 11 positioned below; taking out the steel bar anchor head 11, the steel plate 12 and the hydraulic servo unit 13 from top to bottom; cutting off the uplift pile reinforcing steel bars 7 to the top of the anti-floating plate 14; and constructing a main body structure.
According to the invention, the hydraulic servo control system 16 can be used for accurately controlling the output axial pressure according to the floating deformation condition of the tunnel, so that the overlying soil pressure reduced by excavation and unloading of the tunnel 5 is actively compensated, and the bearing capacity of the uplift pile 6 can be fully exerted, thereby achieving the purpose of controlling the deformation of the tunnel in a regional, real-time and whole process manner.
As can be seen from the foregoing specific embodiments, the method of the present invention that the uplift pile 6 is combined with the anti-floating plate 14 and the shaft is used to excavate the foundation pit is described in detail with reference to specific data; it should be noted that the excavation mode of the foundation pit is not limited to the jump excavation mode of the vertical shaft, and a mode of excavating the foundation pit in a layered and segmented manner as shown in fig. 5 may also be adopted; furthermore, as for the above-mentioned mode of combining the uplift pile 6 with the uplift plates 14, the mode shown in fig. 9 to 13, that is, the mode of combining the uplift anchor rods 17 with the uplift pile 6 and the uplift plates 14 instead of the uplift pile 6 can be adopted to realize the control of the tunnel deformation; wherein, the anti-pulling anchor rod 17 can also be an anti-pulling anchor cable; moreover, the above embodiment is mainly described with respect to the parallel position relationship between the foundation pit and the tunnel 5 shown in fig. 2, and similarly, the above embodiment is also applicable to the intersecting position relationship between the foundation pit and the tunnel 5 shown in fig. 3.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, numerous simple modifications can be made to the technical solution of the invention, including combinations of the individual specific technical features in any suitable way. The invention is not described in detail in order to avoid unnecessary repetition. Such simple modifications and combinations should be considered within the scope of the present disclosure as well.
Claims (4)
1. A floating control method for spanning an existing tunnel on a foundation pit by adopting a hydraulic servo system comprises the following construction steps:
a, arranging an in-tunnel monitoring system (22);
b, constructing a foundation pit enclosure structure and a dewatering well;
c, constructing an uplift pile (6), or constructing an uplift anchor rod (17) or an uplift anchor cable;
d, excavating the foundation pit to a specified elevation in a layered and sectional manner or in a vertical shaft manner;
e, forming a buffer layer (10) at the top of the uplift pile (6), constructing the uplift pile buffer layer (10) made of foam or rubber and a PVC protection pipe (9) of the uplift pile steel bar (7), or constructing the PVC protection pipe (9) of the uplift anchor rod or the uplift anchor cable, wherein the uplift pile steel bar (7) or the uplift anchor rod or the uplift anchor cable penetrates through the PVC protection pipe (9);
f, constructing a reinforced concrete anti-floating plate (14);
g, installing a hydraulic servo control system (16), wherein the monitoring system (22) is connected into the hydraulic servo control system (16) through a line (21);
h, repeating the step d to the step g, and adjusting the output value of the hydraulic servo control system (16) according to the tunnel deformation value in the whole process;
i locking the uplift pile (6) in a subsection mode or locking the uplift anchor rod (17) or the uplift anchor cable in a subsection mode, and constructing a main body structure;
in the step c, the minimum short distance between the uplift pile (6) and the tunnel (5) is not less than 1.5m, the minimum short distance is the horizontal distance between the edge of the outer contour of the uplift pile (6) close to one side of the tunnel (5) and the tunnel (5), the pile bottom of the uplift pile is positioned below one time of the diameter of the tunnel from the bottom of the tunnel (5), the uplift force of the uplift pile is not less than 1.5 times of the upper soil covering weight, and the uplift pile is constructed by adopting a full-casing rotary drilling machine;
in the step e, the thickness of the foam or rubber of the uplift pile buffer layer (10) is estimated according to 2 times of the rebound quantity of the pit bottom after excavation and unloading of the foundation pit, and the minimum thickness is not less than 5 cm;
the uplift pile steel bars (7) extending out of the top of the uplift pile (6) penetrate through the buffer layer (10);
in the step f, the anti-floating plate (14) is a cast-in-place reinforced concrete anti-floating plate or a precast slab, a groove for installing a steel plate (12) or an anchorage device (19) is formed in the anti-floating plate (14), the depth of the groove is matched with the height of a steel bar anchor head (11) for fixing the steel plate (12) or the anchorage device (19), and the steel bar anchor head (11) is positioned above the corresponding steel plate (12);
in step i, when a main body structure is applied to an anti-floating plate coverage area, locking the anti-pulling pile (6) or the anti-pulling anchor rod (17) or the anti-pulling anchor cable of the application area in advance, and removing a hydraulic servo unit (13) controlled by the hydraulic servo control system (16), wherein the hydraulic servo unit (13) is installed between two steel plates (12); in the locking process, monitoring the deformation value of the tunnel in real time, wherein the locking value of the uplift pile (6), the uplift anchor rod (17) or the uplift anchor cable cannot enable the overlying pressure of the tunnel (5) to be larger than the soil covering weight on the tunnel (5) before excavation, and the tunnel (5) does not have settlement;
in the step e, the PVC protection pipe (9) of the uplift pile steel bar (7) or the PVC protection pipe (9) of the uplift anchor rod or the uplift anchor cable can prevent the uplift pile steel bar (7) or the uplift anchor rod or the uplift anchor cable from being cemented with the anti-floating plate (14), so that the uplift pile steel bar (7) or the uplift anchor rod or the uplift anchor cable and the anti-floating plate can be guaranteed to be stressed independently.
2. The method for controlling upward floating of the foundation pit over the existing tunnel by using the hydraulic servo system according to claim 1, wherein in the step c, under the condition that the rock layer below the tunnel meets the construction requirements, an anti-pulling anchor rod (17) or an anti-pulling anchor cable is selected, wherein the anchoring section of the uplift anchor rod or the uplift anchor cable is embedded into the rock stratum below the tunnel (5), the minimum close distance between the anti-pulling anchor rod or the anti-pulling anchor cable and the tunnel (5) is not less than 1.5m, the minimum short distance between the uplift anchor rod or the uplift anchor cable and the tunnel (5) is the horizontal distance between the edge of the outer contour of the uplift anchor rod or the uplift anchor cable close to one side of the tunnel (5) and the tunnel (5), and the anchoring section of the anti-pulling anchor rod or the anti-pulling anchor cable is positioned below one time of the tunnel diameter at the bottom of the tunnel (5), and the anti-pulling force is not less than 1.5 times of the upper earth covering weight.
3. The method for controlling upward floating of an existing tunnel spanning an excavation pit by using a hydraulic servo system as claimed in claim 1, wherein in the step d, the excavation of the excavation pit adopts a layered and sectional excavation mode or a mode of adopting a shaft jump excavation and constructing a supporting structure (8) so as to control the deformation of the tunnel and ensure the self-stability of the excavation pit.
4. The method for controlling upward floating of the foundation pit across the existing tunnel by using the hydraulic servo system according to claim 1, wherein in the step h, when the output value of the servo system is adjusted according to the tunnel deformation value, the amplitude of each adjustment is controlled, the next adjustment is performed after the tunnel deformation is stable, in the adjustment process, the pressure on the tunnel (5) is not more than the weight of soil covering on the tunnel (5) before excavation, and the tunnel (5) is prevented from sinking.
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| CN113186989A (en) * | 2021-04-20 | 2021-07-30 | 广州地铁设计研究院股份有限公司 | Anti-floating construction method for tunnel |
| CN115467367B (en) * | 2022-08-17 | 2023-06-16 | 湖北工业大学 | Construction method for actively compensating deformation of underpass operation tunnel in upper engineering construction |
| CN116220058B (en) * | 2023-05-04 | 2023-08-18 | 济南轨道交通集团有限公司 | Pre-pressing anchor cable beam sinking method technology for controlling excavation deformation of foundation pit above existing tunnel |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101294389A (en) * | 2008-02-22 | 2008-10-29 | 中建国际建设有限公司 | Steel shotcrete support internal force self-compensation, displacement control system and control method |
| CN103790164A (en) * | 2014-01-23 | 2014-05-14 | 中铁四局集团有限公司上海分公司 | Construction method for having control over floating deformation of existing pipeline tunnel in mollisol deep foundation pit excavation |
| CN105240018A (en) * | 2015-10-30 | 2016-01-13 | 中铁上海工程局集团有限公司 | Vertical shaft construction device and method |
-
2020
- 2020-02-21 CN CN202010106538.6A patent/CN111395348B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101294389A (en) * | 2008-02-22 | 2008-10-29 | 中建国际建设有限公司 | Steel shotcrete support internal force self-compensation, displacement control system and control method |
| CN103790164A (en) * | 2014-01-23 | 2014-05-14 | 中铁四局集团有限公司上海分公司 | Construction method for having control over floating deformation of existing pipeline tunnel in mollisol deep foundation pit excavation |
| CN105240018A (en) * | 2015-10-30 | 2016-01-13 | 中铁上海工程局集团有限公司 | Vertical shaft construction device and method |
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