CN112554247A - Foundation pit monitoring system - Google Patents
Foundation pit monitoring system Download PDFInfo
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- CN112554247A CN112554247A CN202011431972.8A CN202011431972A CN112554247A CN 112554247 A CN112554247 A CN 112554247A CN 202011431972 A CN202011431972 A CN 202011431972A CN 112554247 A CN112554247 A CN 112554247A
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 201
- 238000006073 displacement reaction Methods 0.000 claims abstract description 179
- 238000012806 monitoring device Methods 0.000 claims abstract description 60
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 54
- 238000011065 in-situ storage Methods 0.000 claims abstract description 37
- 239000011150 reinforced concrete Substances 0.000 claims abstract description 19
- 230000002093 peripheral effect Effects 0.000 claims abstract description 18
- 238000009412 basement excavation Methods 0.000 claims description 33
- 229910000831 Steel Inorganic materials 0.000 claims description 32
- 239000010959 steel Substances 0.000 claims description 32
- 238000004062 sedimentation Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 description 8
- 239000004576 sand Substances 0.000 description 8
- 239000004568 cement Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 238000009825 accumulation Methods 0.000 description 6
- 238000009435 building construction Methods 0.000 description 5
- 238000005553 drilling Methods 0.000 description 5
- 239000002689 soil Substances 0.000 description 5
- 238000013461 design Methods 0.000 description 3
- 239000003673 groundwater Substances 0.000 description 3
- 230000003014 reinforcing effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000004744 fabric Substances 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000009527 percussion Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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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
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Foundations (AREA)
Abstract
The invention discloses a foundation pit monitoring system, which comprises: the deep horizontal displacement monitoring device is used for monitoring the deep horizontal displacement of the cast-in-situ bored pile; the jacking horizontal displacement monitoring device is used for monitoring the jacking horizontal displacement of the cast-in-situ bored pile; the jacking settlement displacement monitoring equipment is used for monitoring the jacking settlement displacement of the cast-in-situ bored pile; the upright post settlement displacement monitoring equipment is used for monitoring the upright post settlement displacement of the upright post; the supporting shaft force monitoring device is used for monitoring the supporting shaft force of the reinforced concrete inner support; the building settlement displacement monitoring equipment is used for monitoring the settlement displacement of the building around the foundation pit; the ground settlement displacement monitoring equipment is used for monitoring the peripheral ground settlement displacement of the foundation pit; and the water level monitoring equipment is used for monitoring the underground water level of the foundation pit. By the foundation pit monitoring system, the monitoring data of each monitoring project of the foundation pit is obtained, so that the actual working condition of the foundation pit is obtained according to the monitoring data.
Description
Technical Field
The invention relates to the field of building construction, in particular to a foundation pit monitoring system.
Background
In urban building construction, a foundation pit needs to be excavated at the initial stage of the building construction, and the foundation pit refers to a soil pit excavated at the design position of a foundation according to the elevation of the foundation and the plane size of the foundation.
In the building construction process, the actual working condition of foundation pit influences the building construction progress and security, and at present, in the correlation technique, does not provide the technical scheme of obtaining the actual working condition of foundation pit.
Disclosure of Invention
The invention mainly aims to provide a foundation pit monitoring system, and aims to solve the technical problem that a technical scheme for acquiring the actual working condition of a foundation pit is not provided in the prior art.
In order to achieve the purpose, the invention provides a foundation pit monitoring system, wherein the foundation pit is provided with a building enclosure and a stand column, and the building enclosure comprises a cast-in-situ bored pile and a reinforced concrete inner support; the foundation pit monitoring system comprises:
the deep horizontal displacement monitoring device is used for monitoring the deep horizontal displacement of the cast-in-situ bored pile;
the jacking horizontal displacement monitoring device is used for monitoring jacking horizontal displacement of the cast-in-situ bored pile;
the jacking settlement displacement monitoring equipment is used for monitoring the jacking settlement displacement of the cast-in-situ bored pile;
the upright post settlement displacement monitoring equipment is used for monitoring the upright post settlement displacement of the upright post;
the supporting shaft force monitoring device is used for monitoring the supporting shaft force of the reinforced concrete inner support;
the building settlement displacement monitoring equipment is used for monitoring the settlement displacement of the buildings around the foundation pit;
the ground settlement displacement monitoring equipment is used for monitoring the peripheral ground settlement displacement of the foundation pit;
and the water level monitoring equipment is used for monitoring the underground water level of the foundation pit.
Alternatively to this, the first and second parts may,
the deep horizontal displacement monitoring equipment comprises an inclined side pipe and an inclinometer, wherein the inclined side pipe is embedded in the cast-in-situ bored pile, the embedded depth of the inclined side pipe corresponds to that of the cast-in-situ bored pile, and the inclinometer is used for monitoring the horizontal displacement of the inclined side pipe.
Alternatively to this, the first and second parts may,
the jacking horizontal displacement monitoring device comprises a first measuring element and a first precision total station, wherein the first measuring element is arranged at the top of the cast-in-situ bored pile, and the first precision total station is used for monitoring the horizontal displacement of the first measuring element;
the capping settlement displacement monitoring device comprises a second precision total station for monitoring the settlement displacement of the first measuring element.
Alternatively to this, the first and second parts may,
the upright column settlement displacement monitoring equipment comprises a second measuring element and a first level gauge, wherein the second measuring element is arranged at the top of the upright column, and the first level gauge is used for monitoring the settlement displacement of the second measuring element.
Alternatively to this, the first and second parts may,
the supporting shaft force monitoring equipment comprises a frequency reading instrument and a steel bar stress meter, the steel bar stress meter is arranged on a steel bar supported in the reinforced concrete, and the frequency reading instrument is used for acquiring data of the steel bar stress meter.
Alternatively to this, the first and second parts may,
the building settlement displacement monitoring equipment comprises a third measuring element and a second level gauge, wherein the third measuring element is arranged on the peripheral building, and the second level gauge is used for monitoring the settlement displacement of the third measuring element;
the ground settlement displacement monitoring equipment comprises a fourth measuring element and a third level gauge, wherein the third measuring element is arranged on the peripheral ground, and the third level gauge is used for monitoring the settlement displacement of the fourth measuring element.
Alternatively to this, the first and second parts may,
the water level monitoring equipment comprises an electric measuring water level gauge and the observation hole, the observation hole is formed in the outer side of the foundation pit, and the electric measuring water level gauge is used for monitoring the water level of the observation hole.
Alternatively to this, the first and second parts may,
the deep horizontal displacement monitoring device is configured to alarm when the deep horizontal displacement accumulated value is greater than or equal to 40mm and the deformation rate is greater than or equal to 2 mm/d;
the capping horizontal displacement monitoring device is configured to give an alarm when monitoring that the capping horizontal displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/d;
the capping settlement displacement monitoring device is configured to give an alarm when monitoring that the capping settlement displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/d;
the upright post sedimentation displacement monitoring device is configured to give an alarm when the upright post sedimentation displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 0.5 mm/d;
the support axial force monitoring device is configured to alarm when the support axial force values are monitored to be greater than or equal to 4480KN, 5984KN, and 6800KN, respectively;
the building settlement displacement monitoring device is configured to give an alarm when the accumulated value of the surrounding ground settlement displacement is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/day;
the ground settlement displacement monitoring device is configured to give an alarm when the peripheral building settlement displacement accumulated value is greater than or equal to 8mm and the deformation rate is greater than or equal to 0.5 mm/d;
the water level monitoring device is configured to alarm when the underground water level deformation rate is monitored to be greater than or equal to 500 mm/d.
Optionally, in the process of earth excavation of the foundation pit, the foundation pit monitoring system is configured to monitor once every 2 days; the excavation monitoring system is configured to monitor once per week after the floor of the excavation is poured.
Optionally, the monitoring starting point of the monitoring time of the foundation pit monitoring system is the excavation time of the foundation pit, and the monitoring end point of the monitoring time of the foundation pit monitoring system is the completion time of the basement of the foundation pit.
According to the technical scheme, the foundation pit monitoring system is adopted, the foundation pit is provided with a support structure and an upright post, and the support structure comprises a cast-in-situ bored pile and a reinforced concrete inner support; the device comprises: the deep horizontal displacement monitoring device is used for monitoring the deep horizontal displacement of the cast-in-situ bored pile; the jacking horizontal displacement monitoring device is used for monitoring jacking horizontal displacement of the cast-in-situ bored pile; the jacking settlement displacement monitoring equipment is used for monitoring the jacking settlement displacement of the cast-in-situ bored pile; the upright post settlement displacement monitoring equipment is used for monitoring the upright post settlement displacement of the upright post; the supporting shaft force monitoring device is used for monitoring the supporting shaft force of the reinforced concrete inner support; the building settlement displacement monitoring equipment is used for monitoring the settlement displacement of the buildings around the foundation pit; the ground settlement displacement monitoring equipment is used for monitoring the peripheral ground settlement displacement of the foundation pit; and the water level monitoring equipment is used for monitoring the underground water level of the foundation pit. By the foundation pit monitoring system, the monitoring data of each monitoring project of the foundation pit is obtained, so that the actual working condition of the foundation pit is obtained according to the monitoring data.
Drawings
FIG. 1 is a schematic structural diagram of a foundation pit monitoring system according to a first embodiment of the present invention;
FIG. 2 is a schematic diagram of a main structure of item A according to the first embodiment of the present invention;
FIG. 3 is a schematic diagram of the principle of inclined side of the deep horizontal displacement monitoring device according to the present invention;
FIG. 4 is a schematic view of a structure of a measuring point corresponding to the capping horizontal displacement monitoring device of the present invention;
FIG. 5 is a schematic view of the cross-sectional installation position of the steel bar stress gauge of the present invention;
FIG. 6 is a schematic view of the connection of the steel bar stress gauge of the present invention;
FIG. 7 is a schematic view of the structure of the measuring points corresponding to the groundwater level monitoring device of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a foundation pit monitoring system according to a first embodiment of the present invention, where the foundation pit monitoring system includes:
the deep horizontal displacement monitoring equipment 101 is used for monitoring the deep horizontal displacement of the cast-in-situ bored pile;
the jacking horizontal displacement monitoring equipment 102 is used for monitoring the jacking horizontal displacement of the cast-in-situ bored pile;
the jacking settlement displacement monitoring equipment 103 is used for monitoring the jacking settlement displacement of the cast-in-situ bored pile;
the upright post settlement displacement monitoring equipment 104 is used for monitoring upright post settlement displacement of the upright post;
a support axial force monitoring device 105 for monitoring a support axial force of the reinforced concrete inner support;
the building settlement displacement monitoring equipment 106 is used for monitoring the settlement displacement of the buildings around the foundation pit;
the ground settlement displacement monitoring equipment 107 is used for monitoring the surrounding ground settlement displacement of the foundation pit;
and the water level monitoring equipment 108 is used for monitoring the underground water level of the foundation pit.
Referring to fig. 2, fig. 2 is a schematic diagram of a main structure of item a according to the first embodiment of the present invention. The north side base of the foundation pit A is a road B, the north side of the foundation pit A is also provided with a building C, the east side of the foundation pit A is a road D, the south side of the foundation pit A is a road E, and the south side of the foundation pit A is also provided with a building F; and a building G is arranged on the west side of the foundation pit A.
The north side excavation side line of the foundation pit is 11.3m closest to the central line of the B road, 30.4m closest to the existing building, and the east side excavation side line of the foundation pit is 17.7m closest to the central line of the C road; the distance between the excavation edge line of the foundation pit at the south side and the public line D is about 33.7m nearest and 81m away from the existing building; the side line of the west side foundation pit excavation is about 15m closest to the existing building.
The practical floor area of the project A is 13333.10 square meters, the total building area is 56530.95 square meters, the project needs to be subjected to foundation pit excavation, the foundation pit is slightly rectangular, the area of the foundation pit is about 11637 square meters, and the perimeter is about 451.6 m. The elevation of the natural ground around the foundation pit is-1.00 m, the elevation of the excavation surface of the foundation pit is-7.10-12.90 m, and the excavation depth is about 6.10-12.90 m.
The safety level of the foundation pit enclosure structure is first grade, and the design service life of the enclosure structure is two years. The foundation pit support structure comprises: the single-row (local CD section double-row) bored pile, the reinforced concrete inner support (two-way) and the single-row triaxial cement mixing pile, and the deep mixing pile is adopted in the pit for pit bottom reinforcement. The diameter of the drilled pile is 1000mm, the length of the pile is 30-39 m, and the distance between the piles is 1300 mm. Two-layer internal support is arranged, and the main beam of the support beam has the size of 1200 multiplied by 800 mm. The diameter of the triaxial cement mixing pile is phi 850, the center distance of the pile is 600, the lap joint is 250, and the pile length is 12 m; the pit bottom reinforced soil adopts a biaxial cement stirring pile, the diameter is 700 mm, the pile body is vertically and horizontally lapped for 200 mm, and the pile length is 4 m. Two reinforced concrete inner supports are arranged in the foundation pit, and the elevations of the central line of each inner support beam are-2.400 and-5.900 respectively. The upright column is a steel lattice column, a cast-in-situ bored pile is used as a foundation, the diameter of the pile is phi 800, the length of the pile is 28-32m, and the distance from the pile end to the 5 th layer of silt is not less than 5 m.
Concrete strength grade: the crown beam and the inner support are C35, and the pile body is underwater C30. The triaxial cement mixing pile adopts 42.5(R) cement, and the cement mixing ratio is 17%. The water-cement ratio is 1.5-2.0.
In addition, the item A is positioned in a sea reclamation area, and rock strata of the sea reclamation area sequentially comprise from top to bottom:
a plain soil filling layer: the height of the top of the layer is 0.31 to-0.83 m, the thickness of the exposed layer is 1.10 to 3.40 m, and the average thickness is 1.83 m;
mucky soil layer: the buried depth of the top of the layer is 1.10-3.40 meters, the elevation of the top of the layer is-1.24-3.59 meters, the thickness of the exposed layer is 1.20-4.80 meters, and the average thickness is 3.31 meters;
a silt layer: the buried depth of the top of the layer is 4.40-6.30 meters, the elevation of the top of the layer is-4.54-6.65 meters, the thickness of the exposed layer is 4.00-8.50 meters, and the average thickness is 7.08 meters;
mucky soil layer: the buried depth of the top of the layer is 8.50-13.80 meters, the elevation of the top of the layer is-8.79-13.91 meters, the exposed layer thickness is 20.50-27.60 meters, the average is 22.73 meters, and the whole field is distributed separately; is gray black to gray brown;
a medium sand layer: the buried depth of the top of the layer is 33.80-36.20 meters, the elevation of the top of the layer is-34.09-36.92 meters, the exposed layer thickness is 3.20-8.20 meters, the average thickness is 5.53 meters, and the whole area is distributed; the sand is light gray, medium dense-dense and saturated, the medium sand accounts for 50-70%, and the balance is fine sand and coarse sand.
The deep horizontal displacement monitoring equipment comprises an inclined side pipe and an inclinometer, wherein the inclined side pipe is embedded in the cast-in-situ bored pile, the embedded depth of the inclined side pipe corresponds to that of the cast-in-situ bored pile, and the inclinometer is used for monitoring the horizontal displacement of the inclined side pipe.
For the project A, the number of the measuring points corresponding to the deep-layer horizontal displacement monitoring equipment is 8; namely, 8 inclinometers are buried in the cast-in-situ bored pile of item A, the buried depth of the inclinometer is the same as that of the cast-in-situ bored pile, and the buried depth is about 30-39 m of the pile length. The horizontal displacement of the enclosure pile body at different depths is monitored from bottom to top by taking the pipe bottom of the inclined side pipe as a fixed datum point, and the test precision can reach 0.1mm by using a Geoken603 inclinometer imported from America.
Referring to fig. 3, fig. 3 is a schematic diagram of an oblique side principle corresponding to the deep horizontal displacement monitoring device of the present invention, which includes a measuring and reading device, a cable, a side head, a bore (an excavated hole corresponding to an oblique side pipe), a guide pipe (an oblique side pipe), a backfill, a guide wheel and a guide groove; and the displacement is calculated using the following formula:
ΔXi＝Xi-Xi0
wherein, Δ XiCumulative displacement to depth i (to the nearest 0.1mm), XiThis coordinate (mm), X, of depth ii0Is an initial coordinate (mm) of depth i, AjFor reading of the measuring and reading device in the 0 ° direction, BjThe reading of the measuring and reading equipment in the 180-degree direction is carried out, C is a measuring head calibration coefficient, L is the length (mm) of the measuring head, and alphajIs an inclination angle.
During measurement, a measuring head of the inclinometer is connected with a signal transmission line marked with scales (generally one mark per 500mm), the other end of the signal line is connected with a reading instrument, the measuring head of the inclinometer is placed into a tube along a directional slot of the inclinometer tube and slides to the bottom of the tube, reading is upwards pulled at intervals of a certain distance (500mm), and the change of the inclination angle between the inclinometer and a vertical line is measured, so that the horizontal displacement of parts at different depths can be obtained.
Since the inclinometer measures the relative displacement between two pairs of rollers (500mm in height), the fixed point in the inclinometer must be selected as the reference point for measurement, and the bottom end of the tube is generally the fixed point. If the bottom end cannot be ensured to be fixed, the absolute horizontal displacement of the point is measured by using a theodolite or other means by taking the tube top as a reference point so as to calculate the absolute horizontal displacement of the inclinometer at different depths.
The remarks of inclination measurement:
a. embedding the inclinometer pipe and keeping the inclinometer pipe vertical;
b. the inclinometer pipe is provided with two pairs of orientation grooves which are mutually vertical in direction, wherein one pair of orientation grooves needs to be vertical to the side line of the foundation pit;
c. during measurement, the temperature of the inclinometer and the temperature in the pipe must be basically consistent, and the measurement can be started only when the reading of the measurement and reading equipment is stable.
The jacking horizontal displacement monitoring device comprises a first measuring element and a first precision total station, wherein the first measuring element is arranged at the top of the cast-in-situ bored pile, and the first precision total station is used for monitoring the horizontal displacement of the first measuring element; the capping settlement displacement monitoring device comprises a second precision total station for monitoring the settlement displacement of the first measuring element.
Aiming at the project A, the number of the measuring points corresponding to the jacking horizontal displacement monitoring equipment is 22, the number of the measuring points corresponding to the jacking settlement displacement monitoring equipment is 22, horizontal displacement observation points (which are also used as settlement displacement observation points) are arranged at the top of the cast-in-situ bored pile, and the number of the jacking setting points is 22. A percussion drill is adopted for drilling, then a small steel nail with a cross mark, namely a first measuring element, is embedded, and the horizontal displacement and the settlement displacement of the small steel nail are monitored by utilizing a Nippon Sooka NET1005 precision total station and a polar coordinate method. The precision of the instrument is as follows: measuring angle 0.5', and measuring distance 1mm +1 ppm.
Referring to fig. 4, fig. 4 is a schematic view of a measuring point structure corresponding to the capping settlement displacement monitoring device of the present invention. Small steel nails 31, cast-in-situ bored pile top 32, and cast-in-situ bored pile 33.
The upright column settlement displacement monitoring equipment comprises a second measuring element and a first level gauge, wherein the second measuring element is arranged at the top of the upright column, and the first level gauge is used for monitoring the settlement displacement of the second measuring element.
Aiming at the project A, the number of the measuring points corresponding to the upright post settlement displacement monitoring equipment is 14, 3 leveling points are buried on the posts of the old building (pile foundation) outside the influence range of foundation pit excavation and serve as datum points for settlement observation, and the upright posts are provided with 14 measuring points for upright post settlement. The measuring point structure refers to the horizontal displacement measuring point structure; and a Swiss inlet NAK2 precision level gauge is used for monitoring the column settlement displacement, and the test precision can reach 0.1 mm.
The supporting shaft force monitoring equipment comprises a frequency reading instrument and a steel bar stress meter, the steel bar stress meter is arranged on a steel bar supported in the reinforced concrete, and the frequency reading instrument is used for acquiring data of the steel bar stress meter.
Aiming at the item A, the number of corresponding measuring points of the supporting axial force monitoring device is 28; each monitoring point (each reinforced concrete internal support section) consists of 2 steel bar stressometers, and is arranged on the left side and the right side of a steel bar of the support section, and 1 steel bar is placed in the middle of each side. And each reinforced concrete support is provided with 14 supporting axial force monitoring points, and 28 supporting axial force monitoring points are arranged in the two reinforced concrete inner supports.
Wherein F is the supporting axial force (KN) (the calculation result is accurate to 1KN), and S is the supporting sectional area (m)2)， FiThis reading (Hz), F for the strain gauge0Is the initial reading (Hz) of the stress meter, and K is the calibration coefficient (KN/Hz) of the stress meter2/m2)。
Referring to fig. 5, fig. 5 is a schematic view of a section installation position of the steel bar stress gauge of the present invention; the bar strain gauges 41 are mounted to the bars 42 of the support section. Wherein, support the section and include a plurality of reinforcing bars, reinforcing bar stressometer sets up the reinforcing bar in both sides.
Referring to fig. 6, fig. 6 is a schematic diagram of the connection of the steel bar stress meter of the present invention, the steel bar stress meter 53 is installed on the steel bar 51, and the steel bar stress meter 53 is connected to the frequency reading instrument through the cable 52.
In specific application, the steel bar stress meter can be a JTM-V1000DA vibrating wire type steel bar stress meter, and the frequency reading instrument can be a JTM-V10A frequency reading instrument.
The building settlement displacement monitoring equipment comprises a third measuring element and a second level gauge, wherein the third measuring element is arranged on the peripheral building, and the second level gauge is used for monitoring the settlement displacement of the third measuring element; the ground settlement displacement monitoring equipment comprises a fourth measuring element and a third level gauge, wherein the third measuring element is arranged on the peripheral ground, and the third level gauge is used for monitoring the settlement displacement of the fourth measuring element.
According to the project A, 17 measuring points are included corresponding to the peripheral building settlement displacement monitoring equipment, and 17 measuring points are included corresponding to the peripheral ground settlement displacement monitoring equipment. And drilling holes at each measuring point by adopting a percussion drill, then embedding small steel nails, and monitoring by using a Swiss W-Te NAK2 precision level gauge, wherein the measuring precision can reach 0.1 mm.
The water level monitoring equipment comprises an electric measuring water level gauge and the observation hole, the observation hole is formed in the outer side of the foundation pit, and the electric measuring water level gauge is used for monitoring the water level of the observation hole.
According to the project A, a water level observation hole is buried in the outer side of the foundation pit, and a domestic steel ruler water level meter is adopted for monitoring. The water level pipe is made of calcium plastic pipe (the outer diameter is 6cm) and should be buried before excavation. The water level observation holes are buried by a drilling method, 9 water level observation holes are formed in the water level observation holes, and the buried depth is about 10 m. The middle section of the water level pipe is manufactured into a flower tube shape (punched), filter cloth is wound outside the flower tube shape, the bottom end of the water level pipe is sealed, in order to avoid filter cloth blockage, clear water is adopted for drilling in the drilling construction, the water level pipe is conveyed into a preset position in a hole after hole forming, and coarse sand is filled around the water level pipe.
During measurement, the fastening screw behind the wire spool is unscrewed, the power button is pressed after the wire spool rotates freely, the measuring head is placed in the water level pipe, the steel ruler cable is held by hand, and when the contact of the measuring head contacts the water surface, the sounder of the receiving system can make continuous beeping. And reading the depth dimension of the steel ruler cable at the pipe orifice, namely the distance between the underground water level and the pipe orifice. And reducing the water level depth from the orifice elevation to obtain the water level elevation, wherein the initial water level is the average value of continuous secondary tests. The difference between the water level elevation and the initial water level elevation is measured every time, and the difference is the accumulated variation of the water level.
Referring to fig. 7, fig. 7 is a schematic view of a measuring point structure corresponding to the groundwater level monitoring device of the invention. The method comprises the following steps: PVC pipe 64, backfill mud ball 63, backfill yellow sand 62, and permeable section 61.
According to the technical scheme, the foundation pit monitoring system is adopted, the foundation pit is provided with a support structure and an upright post, and the support structure comprises a cast-in-situ bored pile and a reinforced concrete inner support; the device comprises: the deep horizontal displacement monitoring device is used for monitoring the deep horizontal displacement of the cast-in-situ bored pile; the jacking horizontal displacement monitoring device is used for monitoring jacking horizontal displacement of the cast-in-situ bored pile; the jacking settlement displacement monitoring equipment is used for monitoring the jacking settlement displacement of the cast-in-situ bored pile; the upright post settlement displacement monitoring equipment is used for monitoring the upright post settlement displacement of the upright post; the supporting shaft force monitoring device is used for monitoring the supporting shaft force of the reinforced concrete inner support; the building settlement displacement monitoring equipment is used for monitoring the settlement displacement of the buildings around the foundation pit; the ground settlement displacement monitoring equipment is used for monitoring the peripheral ground settlement displacement of the foundation pit; and the water level monitoring equipment is used for monitoring the underground water level of the foundation pit. By the foundation pit monitoring system, the monitoring data of each monitoring project of the foundation pit is obtained, so that the actual working condition of the foundation pit is obtained according to the monitoring data.
Further, the deep level displacement monitoring device is configured to monitor the deep level displacement allowance as an accumulated value not exceeding 20 mm;
the capping horizontal displacement monitoring device is configured to monitor the capping horizontal displacement allowed value as not exceeding 30mm in accumulation;
the capping settlement displacement monitoring device is configured to monitor the capping settlement displacement allowable value as not exceeding 30mm in accumulation;
the upright post settlement displacement monitoring equipment is configured to monitor that the allowable value of the upright post settlement displacement is not more than 30mm in accumulation;
the support axis force monitoring device is configured to monitor the support axis force allowable values not exceeding 5600KN, 7480KN, and 8500KN, respectively;
the building settlement displacement monitoring device is configured to monitor the allowable value of the surrounding ground settlement displacement to be less than 30mm in accumulation;
the ground settlement displacement monitoring device is configured to monitor the allowable value of the settlement displacement of the surrounding building to be not more than 10mm in accumulation;
the water level monitoring device is configured to monitor the allowed value of the groundwater level to be not more than 1000mm in accumulation.
Further, the deep horizontal displacement monitoring device is configured to alarm when the deep horizontal displacement accumulated value is greater than or equal to 40mm and the deformation rate is greater than or equal to 2 mm/d;
the capping horizontal displacement monitoring device is configured to give an alarm when monitoring that the capping horizontal displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/d;
the capping settlement displacement monitoring device is configured to give an alarm when monitoring that the capping settlement displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/d;
the upright post sedimentation displacement monitoring device is configured to give an alarm when the upright post sedimentation displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 0.5 mm/d;
the support axial force monitoring device is configured to alarm when the support axial force values are monitored to be greater than or equal to 4480KN, 5984KN, and 6800KN, respectively;
the building settlement displacement monitoring device is configured to give an alarm when the accumulated value of the surrounding ground settlement displacement is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/day;
the ground settlement displacement monitoring device is configured to give an alarm when the peripheral building settlement displacement accumulated value is greater than or equal to 8mm and the deformation rate is greater than or equal to 0.5 mm/d;
the water level monitoring device is configured to alarm when the underground water level deformation rate is monitored to be greater than or equal to 500 mm/d.
Further, during the earth excavation of the foundation pit, the foundation pit monitoring system is configured to monitor once every 2 days; the excavation monitoring system is configured to monitor once per week after the floor of the excavation is poured.
Further, the monitoring frequency is increased when one of the following conditions is encountered:
1) any item parameter in the monitoring items of the foundation pit reaches an alarm value;
2) the parameter change rate of any monitoring item in the monitoring items exceeds a preset threshold value or the parameter value changes greatly;
3) in the excavation process of the foundation pit, a bad geological condition which is not found in the investigation exists;
4) the pile load or dynamic load of the peripheral ground of the foundation pit exceeds a design limit value;
5) the support structure is not arranged in time during the overexcavation of the foundation pit;
6) in the excavation process of the foundation pit, continuous rainfall, water leakage of the foundation pit or water leakage of a peripheral water pipe (ditch);
7) the foundation pit enclosure structure, the surrounding ground or the surrounding building is subjected to sudden deformation or cracking;
8) piping, leakage or sand flow appears on the side wall or the bottom of the foundation pit;
9) the reinforced concrete inner support is dismantled or replaced;
furthermore, the monitoring starting point of the monitoring time of the foundation pit monitoring system is the excavation time of the foundation pit, and the monitoring end point of the monitoring time of the foundation pit monitoring system is the completion time of the basement of the foundation pit.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A foundation pit monitoring system is characterized in that a foundation pit is provided with a building enclosure and a stand column, wherein the building enclosure comprises a cast-in-situ bored pile and a reinforced concrete inner support; the foundation pit monitoring system comprises:
the deep horizontal displacement monitoring device is used for monitoring the deep horizontal displacement of the cast-in-situ bored pile;
the jacking horizontal displacement monitoring device is used for monitoring jacking horizontal displacement of the cast-in-situ bored pile;
the jacking settlement displacement monitoring equipment is used for monitoring the jacking settlement displacement of the cast-in-situ bored pile;
the upright post settlement displacement monitoring equipment is used for monitoring the upright post settlement displacement of the upright post;
the supporting shaft force monitoring device is used for monitoring the supporting shaft force of the reinforced concrete inner support;
the building settlement displacement monitoring equipment is used for monitoring the settlement displacement of the buildings around the foundation pit;
the ground settlement displacement monitoring equipment is used for monitoring the peripheral ground settlement displacement of the foundation pit;
and the water level monitoring equipment is used for monitoring the underground water level of the foundation pit.
2. The excavation monitoring system of claim 1,
the deep horizontal displacement monitoring equipment comprises an inclined side pipe and an inclinometer, wherein the inclined side pipe is embedded in the cast-in-situ bored pile, the embedded depth of the inclined side pipe corresponds to that of the cast-in-situ bored pile, and the inclinometer is used for monitoring the horizontal displacement of the inclined side pipe.
3. The excavation monitoring system of claim 1,
the jacking horizontal displacement monitoring device comprises a first measuring element and a first precision total station, wherein the first measuring element is arranged at the top of the cast-in-situ bored pile, and the first precision total station is used for monitoring the horizontal displacement of the first measuring element;
the capping settlement displacement monitoring device comprises a second precision total station for monitoring the settlement displacement of the first measuring element.
4. The excavation monitoring system of claim 1,
the upright column settlement displacement monitoring equipment comprises a second measuring element and a first level gauge, wherein the second measuring element is arranged at the top of the upright column, and the first level gauge is used for monitoring the settlement displacement of the second measuring element.
5. The excavation monitoring system of claim 1,
the supporting shaft force monitoring equipment comprises a frequency reading instrument and a steel bar stress meter, the steel bar stress meter is arranged on a steel bar supported in the reinforced concrete, and the frequency reading instrument is used for acquiring data of the steel bar stress meter.
6. The excavation monitoring system of claim 1,
the building settlement displacement monitoring equipment comprises a third measuring element and a second level gauge, wherein the third measuring element is arranged on the peripheral building, and the second level gauge is used for monitoring the settlement displacement of the third measuring element;
the ground settlement displacement monitoring equipment comprises a fourth measuring element and a third level gauge, wherein the third measuring element is arranged on the peripheral ground, and the third level gauge is used for monitoring the settlement displacement of the fourth measuring element.
7. The excavation monitoring system of claim 1,
the water level monitoring equipment comprises an electric measuring water level gauge and the observation hole, the observation hole is formed in the outer side of the foundation pit, and the electric measuring water level gauge is used for monitoring the water level of the observation hole.
8. The excavation monitoring system of claim 1,
the deep horizontal displacement monitoring device is configured to alarm when the deep horizontal displacement accumulated value is greater than or equal to 40mm and the deformation rate is greater than or equal to 2 mm/d;
the capping horizontal displacement monitoring device is configured to give an alarm when monitoring that the capping horizontal displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/d;
the capping settlement displacement monitoring device is configured to give an alarm when monitoring that the capping settlement displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/d;
the upright post sedimentation displacement monitoring device is configured to give an alarm when the upright post sedimentation displacement accumulated value is greater than or equal to 24mm and the deformation rate is greater than or equal to 0.5 mm/d;
the support axial force monitoring device is configured to alarm when the support axial force values are monitored to be greater than or equal to 4480KN, 5984KN, and 6800KN, respectively;
the building settlement displacement monitoring device is configured to give an alarm when the accumulated value of the surrounding ground settlement displacement is greater than or equal to 24mm and the deformation rate is greater than or equal to 2 mm/day;
the ground settlement displacement monitoring device is configured to give an alarm when the peripheral building settlement displacement accumulated value is greater than or equal to 8mm and the deformation rate is greater than or equal to 0.5 mm/d;
the water level monitoring device is configured to alarm when the underground water level deformation rate is monitored to be greater than or equal to 500 mm/d.
9. The excavation monitoring system of claim 8, wherein the excavation monitoring system is configured to monitor once every 2 days during the earth excavation of the excavation; the excavation monitoring system is configured to monitor once per week after the floor of the excavation is poured.
10. The foundation pit monitoring system according to claim 9, wherein the monitoring starting point of the monitoring time of the foundation pit monitoring system is excavation time of the foundation pit, and the monitoring end point of the monitoring time of the foundation pit monitoring system is completion time of a basement of the foundation pit.
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