CN115162426A - Monitoring method for foundation pit enclosure deformation - Google Patents
Monitoring method for foundation pit enclosure deformation Download PDFInfo
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- CN115162426A CN115162426A CN202210815744.3A CN202210815744A CN115162426A CN 115162426 A CN115162426 A CN 115162426A CN 202210815744 A CN202210815744 A CN 202210815744A CN 115162426 A CN115162426 A CN 115162426A
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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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Abstract
The invention discloses a monitoring method for foundation pit enclosure deformation, which is characterized in that a plastic pipe is embedded in a capping beam reinforcement cage in advance, the length of the plastic pipe is not less than the thickness of the capping beam, then the capping beam is poured, and an observation hole is formed on the capping beam; inserting a steel bar anchored into the cement soil enclosure into the center of the observation hole, wherein the top surface of the steel bar is 3-5 cm lower than that of the observation hole; setting the center of the top surface of the steel bar as a point C, popping a line segment parallel to the side line of the foundation pit from the point C on two sides of the observation hole, and setting the positions 100mm away from the hole edge on the line segment as a point A and a point B; and the vertical distance from the point C to the AB line represents the deformation condition of the cement soil enclosure body, and corresponding early warning is given according to the distance during daily patrol. The method overcomes the defect of daily monitoring of foundation pit enclosure in the traditional construction site, can synchronously observe the deformation condition of the foundation pit enclosure body and the upper reinforced concrete structure, and timely feeds back and guides the construction site to take protective measures, thereby ensuring the safety of the foundation pit and avoiding the collapse accident of the foundation pit.
Description
Technical Field
The invention relates to the technical field of constructional engineering, in particular to a monitoring method for foundation pit enclosure deformation.
Background
The foundation pit enclosure plays a role in ensuring safety in foundation pit excavation and structural construction, and common foundation pit monitoring means have many types, such as professional third-party monitoring and measuring standard specification, precise instrument and equipment, high requirement, relatively complex monitoring point position embedding and the like. The daily monitoring of construction sites usually focuses on observing the appearance of the enclosure, such as cracks, point displacement, water leakage, and the like. After the foundation pit enclosure such as the cement soil mixing pile, the soil nailing wall and the like is constructed and before the earthwork is excavated, a reinforced concrete capping beam and a reinforced concrete construction road for peripheral construction need to be constructed on the foundation pit cement soil enclosure body. The tensile and compressive capacities of the cement soil enclosure, the reinforced concrete capping beam and the road are greatly different, the cement soil enclosure and the reinforced concrete capping beam cannot be well combined into a whole, and if the cement soil enclosure is stressed at the same time, the cement soil enclosure is bound to crack before the capping beam and the road. Therefore, the lower portion enclosure body is influenced by soil pressure outside the foundation pit possibly during excavation of the foundation pit, the enclosure body is separated from a soil body on the outer side in a cracking mode, the upper portion capping beam and the road are large in tensile and compressive strength and do not yet show obvious cracks, the problem that the lower portion enclosure body cracks are covered by an upper portion reinforced concrete structure is caused, the situation that the cracks deform during foundation pit enclosure cannot be found in time on a construction site, at the moment, the foundation pit enclosure body is deformed in an accelerating mode due to the water seepage effect and the fact that the cracks are filled with rainwater, and the foundation pit collapse accident can be caused.
Disclosure of Invention
The invention aims to solve the technical problem of providing a monitoring method for foundation pit enclosure deformation, which overcomes the defect of daily monitoring of foundation pit enclosure in the traditional construction site, can synchronously observe the deformation condition of a foundation pit enclosure and an upper reinforced concrete structure, and timely feeds back and guides the construction site to take protective measures, thereby ensuring the safety of the foundation pit and avoiding the collapse accident of the foundation pit.
In order to solve the technical problem, the method for monitoring the enclosure deformation of the foundation pit comprises the following steps:
firstly, after the construction of a cement soil enclosure for foundation pit enclosure is finished and before a capping beam and road concrete are poured, embedding a plastic pipe in a capping beam reinforcement cage in advance, wherein the length of the plastic pipe is not less than the thickness of the capping beam, then pouring the capping beam, and forming an observation hole on the capping beam;
inserting a steel bar anchored into the cement-soil enclosure body into the center of the observation hole, wherein the top surface of the steel bar is 3-5 cm lower than that of the observation hole;
step three, setting a cross mark on the top surface of the steel bar, setting the center point of the cross mark as a point C, popping a line segment parallel to the side line of the foundation pit on the surface of the capping beam by taking the point C as the center point on two sides of the observation hole, respectively marking the cross mark at the position 100mm away from the hole edge on the line segment, setting the center point of the cross mark as a point A and a point B, wherein the point A, the point B and the point C are positioned on the same straight line and are parallel to the side line of the foundation pit;
anchoring a point C into the cement enclosure, wherein whether the point C moves or not represents the deformation condition of the cement enclosure, a point A and a point B are on the surface of the capping beam and represent the deformation conditions of the capping beam and the road, if the connecting line between the point C and the point AB is not on the same straight line, the cement enclosure, the capping beam and the road generate relative displacement, if the capping beam and the road have no crack, the cement enclosure deforms, the vertical distance from the point C to the connecting line AB is short, the deformation size of the cement enclosure is reflected, and the larger the vertical distance from the point C to the connecting line AB is, the larger the deformation of the cement enclosure is;
and step five, during daily inspection, firstly observing whether the capping beam and the road around the observation hole crack or not, then further detecting the displacement condition of a point C in the observation hole, connecting the point A and the point B by adopting a ruler to form an entity line segment, measuring the vertical distance from the point C to an AB connecting line, obtaining the deformation condition of the cement soil enclosure, and giving an early warning by comparing with a deformation warning threshold of the cement soil enclosure.
Furthermore, the diameter of the plastic pipe embedded in the capping beam reinforcement cage in advance is 100mm, and the length of the reinforcement anchored in the cement soil enclosure is not less than 1m.
Further, the observation hole is covered by a protective cover.
The method for monitoring the enclosure deformation of the foundation pit adopts the technical scheme that a plastic pipe is embedded in a capping beam reinforcement cage in advance, the length of the plastic pipe is not less than the thickness of the capping beam, then the capping beam is poured, and an observation hole is formed in the capping beam; inserting a steel bar anchored into the cement soil enclosure into the center of the observation hole, wherein the top surface of the steel bar is 3-5 cm lower than that of the observation hole; setting the center of the top surface of the steel bar as a point C, popping a line segment parallel to the side line of the foundation pit from the point C on two sides of the observation hole, and setting a point A and a point B at positions 100mm away from the hole edge on the line segment; and the vertical distance from the point C to the AB line represents the deformation condition of the cement soil enclosure body, and corresponding early warning is given according to the distance during daily patrol. The method overcomes the defect of daily monitoring of foundation pit enclosure in the traditional construction site, can synchronously observe the deformation condition of the foundation pit enclosure body and the upper reinforced concrete structure, and timely feeds back and guides the construction site to take protective measures, thereby ensuring the safety of the foundation pit and avoiding the collapse accident of the foundation pit.
Drawings
The invention is described in further detail below with reference to the following figures and embodiments:
FIG. 1 is a schematic view of arrangement of observation holes in the monitoring method for foundation pit enclosure deformation according to the present invention;
FIG. 2 isbase:Sub>A schematic sectional view taken along line A-A of FIG. 1;
FIG. 3 is a schematic diagram that a point A, a point B and a point C are located on the same straight line before excavation of the foundation pit in the method;
FIG. 4 is a schematic diagram of the positions of points A, B and C after deformation of the cement-soil enclosure in the method.
Detailed Description
Embodiment as shown in fig. 1 to 4, the method for monitoring deformation of a foundation pit support of the present invention includes the following steps:
after the construction of a cement soil enclosure 2 enclosed by a foundation pit 1 is completed and before a capping beam 3 and road concrete are poured, a plastic pipe 4 is embedded in a reinforcement cage of the capping beam 3 in advance, the length of the plastic pipe 4 is not less than the thickness of the capping beam 3, then the capping beam 3 is poured, and an observation hole 31 is formed in the capping beam 3;
inserting a steel bar 5 anchored into the cement soil enclosure body 2 into the center of the observation hole 31, wherein the top surface of the steel bar 5 is 3-5 cm lower than the top surface of the observation hole 31;
step three, setting a cross mark on the top surface of the steel bar 5, setting the center point of the cross mark as a point C, popping a line segment parallel to the side line of the foundation pit 1 on the surface of the capping beam 3 by taking the point C as the center point on two sides of the observation hole 31, respectively marking the cross marks at the positions 100mm away from the hole edge on the line segment, setting the center point of the cross mark as a point A and a point B, and setting the point A, the point B and the point C to be on the same straight line and parallel to the side line of the foundation pit 1;
anchoring a point C into the cement enclosure 2, wherein whether the point C moves or not represents the deformation condition of the cement enclosure 2, a point A and a point B are on the surface of the coping 3 to represent the deformation conditions of the coping 3 and the road, if the connecting line of the point C and the connecting line AB is not on the same straight line, the cement enclosure 2, the coping 3 and the road generate relative displacement, if the coping 3 and the road have no cracks, the cement enclosure 2 deforms, the vertical distance from the point C to the connecting line AB is short, the deformation size of the cement enclosure 2 is reflected, and the larger the vertical distance from the point C to the connecting line AB is, the larger the deformation of the cement enclosure 2 is;
and step five, during daily inspection, firstly observing whether the capping beam 3 and the road around the observation hole 31 crack or not, further detecting the displacement condition of a point C in the observation hole 31, connecting the point A and the point B by adopting a straight ruler to form an entity line segment, measuring the vertical distance from the point C to an AB connecting line to obtain the deformation condition of the cement soil enclosure 2, and giving an early warning by contrasting the deformation warning threshold of the cement soil enclosure 2.
Preferably, the diameter of the plastic pipe 4 embedded in the steel bar cage of the capping beam 3 in advance is 100mm, and the steel bar 5 anchored into the cement enclosure 2 is not less than 1m.
Preferably, the observation hole 31 is covered with a protective cover. The protective cover provides proper protection for the observation hole and prevents muddy water impurities from invading to damage the observation hole.
The positions and the number of the observation holes can be comprehensively considered by combining the point position requirements of a foundation pit monitoring scheme, the distance between the observation holes can be set according to the width of the cement soil enclosure, and the distance between the observation holes and the side of the foundation pit is about 200-300 mm. The method has the advantages of simple point position monitoring arrangement, common and easily-obtained required materials and tools, and simple and convenient observation and inspection operation. The deformation monitoring of the foundation pit enclosure can be realized by setting an observation hole, anchoring a steel bar and setting a point position, observing the point position deviation and observing the surface crack condition of the concrete structure. Compared with the traditional monitoring means such as an inclinometer and the like, the method has the advantages that the measured data can be obtained more quickly and more visually, the initial deformation condition of the cement soil enclosure body can be calculated quickly, and an auxiliary basis is provided for daily inspection of the foundation pit on the construction site.
The method has the advantages of simple and convenient monitoring point location setting and observation, low cost and quick data acquisition, can be used as the supplement of professional monitoring point locations, can be arranged at the point locations which are deemed necessary in the construction field and are not set for professional monitoring, and is more flexible to apply, thereby ensuring the safety of the foundation pit and avoiding the collapse accident of the foundation pit.
Claims (3)
1. A monitoring method for foundation pit support deformation is characterized by comprising the following steps:
firstly, after the construction of a cement soil enclosure for foundation pit enclosure is finished and before a capping beam and road concrete are poured, embedding a plastic pipe in a capping beam reinforcement cage in advance, wherein the length of the plastic pipe is not less than the thickness of the capping beam, then pouring the capping beam, and forming an observation hole on the capping beam;
inserting a steel bar anchored into the cement and soil enclosure body into the center of the observation hole, wherein the top surface of the steel bar is 3-5 cm lower than that of the observation hole;
step three, setting a cross mark on the top surface of the steel bar, setting the center point of the cross mark as a point C, popping a line segment parallel to the side line of the foundation pit on the surface of the capping beam by taking the point C as the center point on two sides of the observation hole, respectively marking the cross mark at the position 100mm away from the hole edge on the line segment, setting the center point of the cross mark as a point A and a point B, wherein the point A, the point B and the point C are positioned on the same straight line and are parallel to the side line of the foundation pit;
anchoring a point C into the cement enclosure, wherein whether the point C moves or not represents the deformation condition of the cement enclosure, a point A and a point B are on the surface of the capping beam and represent the deformation conditions of the capping beam and the road, if the connecting line between the point C and the point AB is not on the same straight line, the cement enclosure, the capping beam and the road generate relative displacement, if the capping beam and the road have no crack, the cement enclosure deforms, the vertical distance from the point C to the connecting line AB is short, the deformation size of the cement enclosure is reflected, and the larger the vertical distance from the point C to the connecting line AB is, the larger the deformation of the cement enclosure is;
and step five, during daily inspection, firstly observing whether the capping beam and the road around the observation hole crack, then further inspecting the displacement condition of a point C in the observation hole, connecting the point A and the point B by adopting a ruler to form an entity line segment, measuring the vertical distance from the point C to the point AB to obtain the deformation condition of the cement soil enclosure, and giving an early warning by comparing with a deformation warning threshold of the cement soil enclosure.
2. The monitoring method for the deformation of the foundation pit enclosure according to claim 1, wherein: the diameter of the plastic pipe embedded in the steel bar cage of the coping beam in advance is 100mm, and the diameter of the steel bar anchored in the cement soil enclosure is not less than 1m.
3. The monitoring method for the deformation of the foundation pit enclosure according to claim 1, wherein: the observation hole is covered by a protective cover.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210815744.3A CN115162426A (en) | 2022-07-12 | 2022-07-12 | Monitoring method for foundation pit enclosure deformation |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210815744.3A CN115162426A (en) | 2022-07-12 | 2022-07-12 | Monitoring method for foundation pit enclosure deformation |
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| CN115162426A true CN115162426A (en) | 2022-10-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202210815744.3A Pending CN115162426A (en) | 2022-07-12 | 2022-07-12 | Monitoring method for foundation pit enclosure deformation |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107023043A (en) * | 2017-05-26 | 2017-08-08 | 中国十七冶集团有限公司 | A kind of deep foundation pit supporting construction monitoring and pre-alarming method |
| CN109778866A (en) * | 2018-12-20 | 2019-05-21 | 上海建工集团股份有限公司 | Combination supporting system and its construction method for foundation pit central island basin excavation |
| CN113550322A (en) * | 2021-07-09 | 2021-10-26 | 上海市基础工程集团有限公司 | Enclosure system next to deep and shallow foundation pit and construction method |
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2022
- 2022-07-12 CN CN202210815744.3A patent/CN115162426A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107023043A (en) * | 2017-05-26 | 2017-08-08 | 中国十七冶集团有限公司 | A kind of deep foundation pit supporting construction monitoring and pre-alarming method |
| CN109778866A (en) * | 2018-12-20 | 2019-05-21 | 上海建工集团股份有限公司 | Combination supporting system and its construction method for foundation pit central island basin excavation |
| CN113550322A (en) * | 2021-07-09 | 2021-10-26 | 上海市基础工程集团有限公司 | Enclosure system next to deep and shallow foundation pit and construction method |
Non-Patent Citations (1)
| Title |
|---|
| 王晓梅: "深基坑监测方法浅析", 城市地质, vol. 10, pages 57 - 61 * |
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