CN111764447A - Method for monitoring horizontal displacement of pile top of foundation pit supporting pile - Google Patents
Method for monitoring horizontal displacement of pile top of foundation pit supporting pile Download PDFInfo
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- CN111764447A CN111764447A CN202010697064.7A CN202010697064A CN111764447A CN 111764447 A CN111764447 A CN 111764447A CN 202010697064 A CN202010697064 A CN 202010697064A CN 111764447 A CN111764447 A CN 111764447A
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 83
- 238000006073 displacement reaction Methods 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000009412 basement excavation Methods 0.000 claims abstract description 7
- 238000010276 construction Methods 0.000 claims description 6
- 230000001681 protective effect Effects 0.000 claims description 4
- 238000004080 punching Methods 0.000 claims description 2
- 239000004576 sand Substances 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract 1
- 238000007619 statistical method Methods 0.000 abstract 1
- 238000009434 installation Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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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- Structural Engineering (AREA)
- Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)
Abstract
The invention relates to a method for monitoring horizontal displacement of a pile top of a foundation pit supporting pile, which is suitable for monitoring the horizontal displacement change of the top of a supporting structure around a foundation pit in a foundation pit excavation stage. The monitoring method comprises the steps of 1, laying plane control points, installing small prisms, calculating plane coordinates, building monitoring points, installing small prisms, selecting foundation pit monitoring work base points and erecting a total station, 2, measuring and calculating initial plane coordinates of each monitoring point position in a multi-measuring-loop mode, 3, repeatedly measuring each monitoring point position at intervals for a certain time, and calculating horizontal displacement change values of the monitoring point positions; 4. and carrying out statistical analysis on the horizontal displacement change value of the monitoring point. The method has the technical effects that the horizontal displacement change condition of the pile top of the foundation pit supporting pile can be conveniently and quickly measured, the deformation speed of the foundation pit supporting pile can be conveniently analyzed, and the safety condition of the foundation pit can be evaluated.
Description
Technical Field
The invention relates to a foundation pit deformation monitoring method, in particular to a monitoring method for horizontal displacement of a pile top of a foundation pit supporting pile.
Background
In order to prevent the collapse of the surrounding soil body in the excavation process of the foundation pit, a support pile is generally continuously driven around the foundation pit and a concrete support is poured, and one or more water-stop curtains are also constructed at the periphery of the foundation pit in the deep foundation pit to prevent the water leakage of the foundation pit. The foundation ditch is monitored supporting structure around digging the in-process, masters structure accumulative total variation and deformation speed for whether aassessment foundation ditch excavation mode, excavation speed are reasonable, guarantee foundation ditch safety. The foundation pit monitoring is an important guarantee for the safety of foundation pit construction.
Disclosure of Invention
The invention aims to provide a method for monitoring horizontal displacement of a pile top of a foundation pit supporting pile, which adopts a monitoring tool comprising a total station, a control point small prism and a monitoring point small prism, and is characterized in that: the monitoring step is that,
scattering and establishing a foundation pit monitoring working base point, a plane control point and a monitoring point, wherein the plane control points are selected from a stable building or a foundation stable area at the periphery of the foundation pit, the foundation pit monitoring working base points are selected from the foundation pit and are respectively composed of a concrete foundation and a concrete upright column, the height of the foundation point working platform is 1.5 m, the base point working platform is in an inverted T shape, and the control point working platform is fixed in the center of the bottom base in the base point, the base in the base point is pre-embedded in the center of the top of the base point working platform, the control point fixing bolt is fixed in the center of the bottom base in the control point, the bottom base in the control point is pre-embedded in the center of the top of the control point working platform, so that the foundation pit monitoring working base is seen through with as many plane control points as possible, the monitoring point is that after the construction of a supporting structure at the, fixing the support structure on the top of the foundation pit concrete support structure in an electric hammer punching mode, covering a U-shaped protective cover on an expansion bolt and inserting the expansion bolt into a concrete groove on the top of the support structure;
fixing a total station on a base point fixing bolt of a foundation pit monitoring working base point, fixing a small prism on a fixing bolt of each control point by using the total station, observing the small prisms of the control points of at least three plane control points, measuring the angles and the distances of the small prisms, calculating plane coordinates of the foundation pit monitoring working base point by using a rear intersection method, namely instrument station setting coordinates, measuring the plane coordinates of the rest plane control points by using the total station, comparing the plane coordinates with the known plane coordinates, evaluating the instrument station setting precision, and performing subsequent work when the error is within the allowable range of the foundation pit monitoring technical scheme;
⑴, collecting initial coordinate value, before digging the foundation pit, taking down the U-shaped protective cover at each monitoring point, installing small monitoring point prisms (6) with known correction constant on the expansion bolts, observing each monitoring point prism at the foundation pit monitoring working base point by using a total station, measuring by adopting a multiple measuring-back mode, wherein the measuring times is more than 2, and calculating the average value of the measured values as the initial plane coordinate value (X) of each monitoring pointFirst stage,YFirst stage)；
⑵, monitoring normally, after the foundation pit is excavated, regularly collecting coordinate values of each monitoring point according to different monitoring frequencies of 1 time/day, 1 time/3 days and 1 time/week required by the frequency of the foundation pit monitoring scheme (coordinate value)Xn,Yn) N represents nth observed data (n is 1,2,3 … …);
performing horizontal displacement change analysis according to a known formula
dx＝Xn-XFirst stage
dy＝yn-YFirst stage
Wherein d issThe value is a horizontal bit variation value dxThe value is a horizontal coordinate variation value dyThe value is a vertical coordinate change value, the horizontal displacement change value of the monitoring point (3) is decomposed into a value along the direction of the foundation pit supporting structure and a value perpendicular to the direction of the foundation pit supporting structure, and the horizontal position change d of the monitoring point (3) of the foundation pit supporting structure is directly reflectedsComparing the variation d of coordinate value of monitoring point with the initial value at each stagesChanging the horizontal displacement of the supporting structure of the foundation pit by a variable dsAnd dividing the observation time interval by the observation time interval to obtain the horizontal displacement change rate, reflecting the horizontal displacement change speed of the top of the foundation pit supporting structure, and facilitating the analysis of the deformation speed and the safety condition of the foundation pit.
The invention has the advantages that the monitoring point installation has simple structure, convenient manufacture, installation and application, is not easily influenced by foundation pit construction and damaged, has simple and convenient monitoring method, and can greatly improve the monitoring efficiency of the horizontal displacement of the pile top of the foundation pit in the later period.
Drawings
FIG. 1 is a diagram of the foundation pit monitoring operation base point, plane control point and monitoring point arrangement of the present invention;
FIG. 2 is a schematic diagram of a planar control point structure of the present invention;
FIG. 3 is a schematic view of the monitoring point expansion bolt installation of the present invention;
FIG. 4 is a schematic view of the mounting of small prisms of the monitoring point according to an embodiment of the present invention.
Detailed Description
The invention is further explained below with reference to the drawings and the embodiments.
As shown in fig. 1 and fig. 2, taking monitoring of a foundation pit within a range of 100 meters × 100 meters as an example, a method for monitoring horizontal displacement of a pile top of a foundation pit supporting pile comprises the steps of establishing a foundation pit monitoring working base point 1, a plane control point 2 and a monitoring point 3, establishing 4 plane control points 2 and selecting a stable building or a stable foundation area at the periphery of the foundation pit, selecting 3 foundation pit monitoring working base points 1 in the foundation pit, respectively adopting a concrete foundation and a concrete upright column to form a base point working platform 1-1 and a control point working platform 2-1 with a height of 1.5 meters and an inverted T shape, fixing bolts 1-4 for the base points are fixed at the center of the base point middle base 1-3, pre-embedding the base point middle base 1-3 at the center of the top of the base point platform working 1-1, fixing a total station 4 on the base point fixing bolts 1-4, fixing bolts 2-4 for the control points are fixed at the center of the control point base, the base 2-3 in the control point is pre-buried in the control point work platform 2-1 top center, the control point small prism 5 is fixed on control point fixing bolt 2-4, make every foundation ditch monitor work base 1 look through with at least 3 level control points, 3 foundation ditch monitor work base 1 distribute in the foundation ditch evenly, the observation range covers all monitoring points 3, after the supporting structure construction of the foundation ditch periphery is finished, expand the bolt 3-1, fix on the concrete supporting structure top of the foundation ditch by the way of electric hammer drilling every 10 meters, install the small prism 6 of monitoring point of the known correction constant on the bolt 3-1 of expansion, need to lay 40 small prisms 6 of monitoring point on the supporting structure of the foundation ditch that the regional scope is 100 meters × 100 meters;
and secondly, controlling measurement and calculating adjustment to obtain the plane coordinates of each control point 2. Observing a control point small prism 5 of at least three plane control points 2 on a foundation pit monitoring working base point 1 by using a total station 4, measuring an angle and a distance, calculating a plane coordinate of the foundation pit monitoring working base point 1 by using a rear intersection method, namely an instrument station setting coordinate, measuring the plane coordinate of the rest plane control points 2 by using the total station 4, comparing the plane coordinate with a known plane coordinate, evaluating the instrument station setting precision, and performing subsequent work when an error is within an allowable range of a foundation pit monitoring technical scheme;
as shown in fig. 3 and 4, in the third step, an L-shaped small prism is fixedly installed on an expansion bolt 3-1 of a monitoring point 3;
fourthly, before excavation of the foundation pit, fixing a total station 4 on base point fixing bolts 1-4 of a base point working platform 1-1, and collecting initial values (x) of plane coordinates of all monitoring points 3c，yc)；
Fifthly, collecting the plane coordinates (x) of the monitoring point 3 once every 3 days in the process of foundation pit excavationi，yi) Calculating the accumulated variation and the variation rate of the horizontal displacement of the top of the foundation pit supporting pile;
and sixthly, after the foundation pit construction is finished, stopping measuring when the horizontal displacement change rate of the pile top is smaller than the standard requirement.
Claims (1)
1. A foundation pit supporting pile top horizontal displacement monitoring method is characterized in that a monitoring tool is provided with a total station (4), a control point small prism (5) and a monitoring point small prism (6), and the method comprises the following steps: the monitoring step is that,
scattering and establishing a foundation pit monitoring working base point (1), a plane control point (2) and a monitoring point (3), wherein the plane control points (2) are selected from a stable building or a foundation stable area at the periphery of a foundation pit, the foundation pit monitoring working base points (1) are selected from the foundation pit and are respectively formed by a concrete foundation and a concrete upright column, the base point working platform (1-1) and the control point working platform (2-1) are 1.5 m in height and are of an inverted T shape, a base point fixing bolt (1-4) is fixed at the center of a base (1-3) in the base point, the base (1-3) in the base point is pre-embedded at the center of the top of the base point working platform (1-1), a control point fixing bolt (2-4) is fixed at the center of a base (2-3) in the control point, the base (2-3) in the control point is pre-embedded at the center of the top, the foundation pit monitoring work base point (1) is made to be in full view with as many plane control points as possible, the monitoring points (3) are that after the construction of a supporting structure around a foundation pit is finished, expansion bolts (3-1) are selected at intervals of 5m, 10m and 20m according to the grade of the foundation pit and fixed to the top of a foundation pit concrete supporting structure in an electric hammer punching mode, and a U-shaped protective cover (3-2) covers the expansion bolts (3-1) and is inserted into a concrete groove at the top of the supporting structure;
the method comprises the steps that a total station instrument (4) is fixed on base point fixing bolts (1-4) of a foundation pit monitoring work base point (1), a small prism (5) is fixed on the fixing bolts (2-4) of each control point by the total station instrument (4), the control point small prisms (5) of at least three plane control points (2) are observed, the angles and the distances of the control point small prisms are measured, the plane coordinates of the foundation pit monitoring work base point (1), namely instrument station setting coordinates, are calculated by a rear intersection method, the plane coordinates of the rest plane control points (2) are measured by the total station instrument (4) and are compared with the known plane coordinates, the instrument station setting precision is evaluated, and the subsequent work can be carried out within the allowable range of a foundation pit monitoring technical scheme;
⑴, collecting initial coordinate values, before excavation of the foundation pit, taking down a U-shaped protective cover (3-2) at each monitoring point, installing a monitoring point small prism (6) with a known correction constant on an expansion bolt (3-1), observing each monitoring point small prism (6) by using a total station (1) at a foundation pit monitoring work base point (1), measuring by adopting a multi-time measuring-back mode, wherein the number of the measuring-back is more than 2, calculating the average value of measured values as the initial plane coordinate value (X) of each monitoring point (3)First stage,YFirst stage)；
⑵, monitoring normally, after the foundation pit is excavated, regularly collecting coordinate values (X) of each monitoring point (3) according to different monitoring frequencies of 1 time/day, 1 time/3 days and 1 time/week required by the frequency of the foundation pit monitoring schemen,Yn) N represents nth observed data (n is 1,2,3 … …);
performing horizontal displacement change analysis according to a known formula
dx＝Xn-XFirst stage
dy＝yn-YFirst stage
Wherein d issThe value is a horizontal bit variation value dxThe value is a horizontal coordinate variation value dyThe value is a vertical coordinate change value,
the horizontal displacement change value of the monitoring point (3) is decomposed into the horizontal displacement change d along the direction of the foundation pit supporting structure and the direction vertical to the foundation pit supporting structure, and the horizontal displacement change d of the monitoring point (3) of the foundation pit supporting structure is directly reflectedsComparing the variation d of coordinate value of monitoring point with the initial value at each stagesWill be based onHorizontal displacement variable d of pit supporting structuresAnd dividing the observation time interval by the observation time interval to obtain the horizontal displacement change rate, reflecting the horizontal displacement change speed of the top of the foundation pit supporting structure, and facilitating the analysis of the deformation speed and the safety condition of the foundation pit.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010697064.7A CN111764447A (en) | 2020-07-20 | 2020-07-20 | Method for monitoring horizontal displacement of pile top of foundation pit supporting pile |
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| CN202010697064.7A CN111764447A (en) | 2020-07-20 | 2020-07-20 | Method for monitoring horizontal displacement of pile top of foundation pit supporting pile |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113188510A (en) * | 2021-03-10 | 2021-07-30 | 浙江省建工集团有限责任公司 | Construction method for new triangular elevation measurement in large-area deep foundation pit |
| CN114541494A (en) * | 2022-03-02 | 2022-05-27 | 中铁七局集团有限公司 | Method for monitoring deformation of pile body of cantilever fender pile of deep foundation pit |
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| CN102409703A (en) * | 2011-08-17 | 2012-04-11 | 北京交通大学 | Monitoring method for horizontal displacement of foundation pit pile top and monitoring device thereof |
| CN103352455A (en) * | 2013-07-30 | 2013-10-16 | 上海城建市政工程（集团）有限公司 | Monitoring method of bottom soil heave of excavation foundation pit |
| WO2020088363A1 (en) * | 2018-10-31 | 2020-05-07 | 中国电建集团山东电力建设第一工程有限公司 | Fast pit marking and lofting method for transmission line foundation |
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2020
- 2020-07-20 CN CN202010697064.7A patent/CN111764447A/en active Pending
Patent Citations (4)
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| JP2009030994A (en) * | 2007-07-24 | 2009-02-12 | Yurtec Corp | Shape measurement method for buried concrete foundation, and device thereof |
| CN102409703A (en) * | 2011-08-17 | 2012-04-11 | 北京交通大学 | Monitoring method for horizontal displacement of foundation pit pile top and monitoring device thereof |
| CN103352455A (en) * | 2013-07-30 | 2013-10-16 | 上海城建市政工程（集团）有限公司 | Monitoring method of bottom soil heave of excavation foundation pit |
| WO2020088363A1 (en) * | 2018-10-31 | 2020-05-07 | 中国电建集团山东电力建设第一工程有限公司 | Fast pit marking and lofting method for transmission line foundation |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113188510A (en) * | 2021-03-10 | 2021-07-30 | 浙江省建工集团有限责任公司 | Construction method for new triangular elevation measurement in large-area deep foundation pit |
| CN113188510B (en) * | 2021-03-10 | 2022-05-27 | 浙江省建工集团有限责任公司 | Construction method for new triangular elevation measurement in large-area deep foundation pit |
| CN114541494A (en) * | 2022-03-02 | 2022-05-27 | 中铁七局集团有限公司 | Method for monitoring deformation of pile body of cantilever fender pile of deep foundation pit |
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