CN108612075B - Method for monitoring horizontal displacement of deep foundation pit - Google Patents

Abstract

The invention provides a method for monitoring horizontal displacement of a deep foundation pit, and relates to the technical field of building measurement. The method comprises the following steps: setting monitoring points at a site to be constructed, and determining a plane rectangular coordinate system through the monitoring points; establishing a rectangular reference line according to a coordinate system and selecting a monitoring point in the rectangular reference line; selecting a reference point on one side of the rectangular reference line, and finding the reference point on the other side corresponding to the reference point; measuring and calculating parameters required by the horizontal displacement of a foundation pit monitoring point through a total station; and calculating the horizontal displacement of the foundation pit. The method for monitoring the horizontal displacement of the deep foundation pit can freely set monitoring points on the rectangular reference line, can randomly switch the monitoring points, is not limited by barriers, is suitable for most foundation pits, greatly improves the monitoring efficiency of the irregular foundation pit, and has more superiority compared with multiple station setting and angle limitation of a small-angle method.

Description

A method for monitoring horizontal displacement of deep foundation pit

technical field

The invention relates to the technical field of building measurement, in particular to a method for monitoring the horizontal displacement of a deep foundation pit.

Background technique

With the rapid development of my country's economy, foundation pit construction is carried out in a complex urban environment, and the monitoring accuracy of the horizontal displacement of the supporting structure of the foundation pit is generally high. At present, the commonly used methods for monitoring the horizontal displacement of the pile top of the foundation pit mainly include the sight line method, the small angle method, the resection method, and the polar coordinate method. The line-of-sight method and the small-angle method are easy to measure, with small computational workload and high measurement accuracy, but these methods often require multiple station setups, which are time-consuming, labor-intensive, low-efficiency, and have many uncertain factors affecting accuracy. The monitoring work of the monitoring personnel is very cumbersome.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the prior art, the present invention provides a method for monitoring the horizontal displacement of a deep foundation pit, which does not need to set up stations many times, but only needs to establish a rectangular reference line in an irregular foundation pit, and the rectangular reference line surrounds the entire foundation pit. The outside of the pit is established, and the horizontal displacement of the building foundation pit can be quickly and accurately measured by using the coordinates on the reference line, which reduces the number of stations set up, improves the efficiency of on-site monitoring, and saves engineering costs.

In order to achieve the above purpose, a method for monitoring the horizontal displacement of a deep foundation pit, comprising the following steps:

Step 1: According to the foundation pit monitoring specification, set up two monitoring points a and b at the construction site, and use the total station to determine the plane rectangular coordinate system c through the two points a and b;

Step 2: Take the foundation pit as the center under the coordinate system c, and establish a rectangular reference line o around the foundation pit. The position of each point on the rectangular reference line o is determined by the rectangular coordinate system c, and any monitoring points that have been marked around the foundation pit are determined. Select a point k for monitoring;

Step 3: Select a reference point m on one side of the established rectangular reference line o, measure at the reference point m with a total station, and find a reference point n on another reference line parallel to the reference line where the reference point m is located, The line connecting the reference points m and n is perpendicular to the reference line where m and n are located;

Step 4: Measure and calculate the parameters required for the horizontal displacement of the foundation pit monitoring point by the total station measurement, including the straight-line distance L ₁ between the reference point m and any point k, and the straight-line distance L ₂ between the reference point n and any point k , the included angle α of the line between the two reference points m and n and the line between the reference point m and any point k, the line between the two reference points m and n, and the line between the reference point n and any point k The included angle β, the straight-line distance L 1 ' between the reference point m and the point k' after the displacement of any point k is changed, and the straight-line distance L ₂ ' between the reference point n and the point k' after the displacement of the arbitrary point k is changed L ₂ ' , the included angle α' of the line between the two reference points m and n and the line between the reference point m and the point k' after the displacement of any point k changes, the line between the two reference points m and n and the reference point n The included angle β' of the line connecting with the point k' after the displacement of any point k is changed;

Step 5: Calculate the horizontal displacement of the foundation pit monitoring point, that is, the horizontal displacement of the foundation pit according to the parameters measured in step 4;

The formula for calculating the horizontal displacement of the foundation pit monitoring point is as follows:

D=(D ₁ +D ₂ )/2;

S=(S ₁ +S ₂ )/2;

Among them, D ₁ is the horizontal displacement of the foundation pit reference point m of the vertical foundation pit side change, D ₂ is the foundation pit reference point n The horizontal displacement of the vertical foundation pit side change, D is the average level of the vertical foundation pit side change of the foundation pit reference point Displacement, S1 is the horizontal displacement _of the foundation pit reference point m parallel to the side of the foundation pit, _S2 is the horizontal displacement of the foundation pit reference point n parallel to the side of the foundation pit, S is the average level of the change of the foundation pit reference point parallel to the side of the foundation pit Displacement; the calculation formulas of the horizontal displacement of the vertical foundation pit side change and the horizontal displacement of the parallel foundation pit side change of the foundation pit reference points m, n are as follows:

D ₁ =(L ₁ cosα-L ₁ 'cosα');

D ₂ =(L ₂ cosβ-L ₂ 'cosβ');

S ₁ =(L ₁ sinα-L ₁ 'sinα');

S ₂ =(L ₂ sinβ-L ₂ 'sinβ').

Beneficial effects of the present invention:

The invention proposes a method for monitoring the horizontal displacement of a deep foundation pit. A coordinate system is established through a reference point, a rectangular reference line is established around the foundation pit with the foundation pit as the center through the coordinate system, and a reference point and a monitoring point on the rectangular reference line are passed. The angle relationship between the connection line and the line connecting the two reference points is simple, fast and easy to calculate the horizontal displacement of the monitoring point. This method can arbitrarily set up monitoring points on the rectangular reference line, and can switch the monitoring points at will without obstacles. It is applicable to most foundation pits, which greatly improves the monitoring efficiency of irregular-shaped foundation pits. Compared with the multiple station setting and angle limitation of the small-angle method, this method is more advantageous. In addition, this method is calculated by measuring and calculating The method of taking the mean value greatly improves the accuracy.

Description of drawings

Fig. 1 is the method flow chart of monitoring the horizontal displacement of deep foundation pit in the embodiment of the present invention;

FIG. 2 is a schematic diagram of on-site monitoring for monitoring the horizontal displacement of a deep foundation pit in an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention.

A method for monitoring the horizontal displacement of a deep foundation pit, the process is shown in Figure 1, and the schematic diagram of on-site monitoring is shown in Figure 2. The specific method is as follows:

Step 1: According to the foundation pit monitoring specification, set up two monitoring points a and b at the construction site, and use the total station to determine the plane rectangular coordinate system c through the two points a and b.

Step 2: Take the foundation pit as the center under the coordinate system c, and establish a rectangular reference line o around the foundation pit. The position of each point on the rectangular reference line o is determined by the rectangular coordinate system c, and any monitoring points that have been marked around the foundation pit are determined. Select a point k for monitoring;

Step 3: Select a reference point m on one side of the established rectangular reference line o, measure at the reference point m with a total station, and find a reference point n on another reference line parallel to the reference line where the reference point m is located, The line connecting the reference points m and n is perpendicular to the reference line where m and n are located.

Step 4: Measure and calculate the parameters required for the horizontal displacement of the foundation pit monitoring point by the total station measurement, including the straight-line distance L ₁ between the reference point m and any point k, and the straight-line distance L ₂ between the reference point n and any point k , the included angle α of the line between the two reference points m and n and the line between the reference point m and any point k, the line between the two reference points m and n, and the line between the reference point n and any point k The included angle β, the straight-line distance L 1 ' between the reference point m and the point k' after the displacement of any point k is changed, and the straight-line distance L ₂ ' between the reference point n and the point k' after the displacement of the arbitrary point k is changed L ₂ ' , the included angle α' of the line between the two reference points m and n and the line between the reference point m and the point k' after the displacement of any point k changes, the line between the two reference points m and n and the reference point n The included angle β' of the line connecting with the point k' after the displacement of any point k is changed.

Step 5: According to the parameters measured in Step 4, calculate the horizontal displacement of the monitoring point of the foundation pit, that is, the horizontal displacement of the foundation pit.

The formula for calculating the horizontal displacement of the monitoring point of the foundation pit is shown in formula (1) and formula (2):

D=(D ₁ +D ₂ )/2 (1)

S=(S ₁ +S ₂ )/2 (2)

Among them, D ₁ is the horizontal displacement of the foundation pit reference point m of the vertical foundation pit side change, D ₂ is the foundation pit reference point n The horizontal displacement of the vertical foundation pit side change, D is the average level of the vertical foundation pit side change of the foundation pit reference point Displacement, S1 is the horizontal displacement _of the foundation pit reference point m parallel to the side of the foundation pit, _S2 is the horizontal displacement of the foundation pit reference point n parallel to the side of the foundation pit, S is the average level of the change of the foundation pit reference point parallel to the side of the foundation pit Displacement; the calculation formulas of the horizontal displacement of the vertical foundation pit side change and the horizontal displacement of the parallel foundation pit side change of the foundation pit reference points m and n are shown in formula (3)-formula (6):

D ₁ =(L ₁ cosα-L ₁ 'cosα′) (3)

D ₂ =(L ₂ cosβ-L ₂ 'cosβ') (4)

S ₁ =(L ₁ sinα-L ₁ 'sinα') (5)

S ₂ =(L ₂ sinβ-L ₂ 'sinβ') (6)

As can be seen from step 4, the present embodiment only needs to measure the degree of 4 side lengths and 4 included angles, and brings into formula (3)-formula (6) to obtain the foundation pit according to formula (1) and formula (2). The horizontal displacement is simple, fast and easy to implement, which greatly improves the monitoring efficiency of irregular-shaped foundation pits. Compared with the multiple station setting and angle limitation of the small-angle method, this method is more advantageous.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand; The technical solutions described in the foregoing embodiments are modified, or some or all of the technical features thereof are equivalently replaced; therefore, these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope defined by the claims of the present invention.

Claims (1)

1. a method for monitoring the horizontal displacement of deep foundation pit, is characterized in that, comprises the following steps: Step 1: According to the foundation pit monitoring specification, set up two monitoring points a and b at the construction site, and use the total station to determine the plane rectangular coordinate system c through the two points a and b; Step 2: Take the foundation pit as the center under the coordinate system c, and establish a rectangular reference line o around the foundation pit. The position of each point on the rectangular reference line o is determined by the rectangular coordinate system c, and any monitoring points that have been marked around the foundation pit are determined. Select a point k for monitoring; Step 3: Select a reference point m on one side of the established rectangular reference line o, measure at the reference point m with a total station, and find a reference point n on another reference line parallel to the reference line where the reference point m is located, The line connecting the reference points m and n is perpendicular to the reference line where m and n are located; Step 4: The parameters required to calculate the horizontal displacement of the monitoring point of the foundation pit are measured by the total station, including the straight-line distance L1 between the reference point m and any point k, the straight-line distance L2 between the reference point n and any point k, and the two The included angle α of the line between the reference point m and n and the line between the reference point m and any point k, the angle between the line between the two reference points m and n and the line between the reference point n and any point k Angle β, the straight-line distance L1' between the reference point m and the point k' after the displacement of any point k's change, the straight-line distance L2' between the reference point n and the point k' after the displacement of any point k's change, the two reference points The included angle α' between the line between m and n and the line between the reference point m and the point k' after the displacement of any point k is changed, the line between the two reference points m and n and the reference point n and any point k The included angle β' of the line connecting the points k' after the displacement changes; Step 5: According to the parameters measured in step 4, calculate the horizontal displacement of any monitoring point k of the foundation pit, that is, the horizontal displacement of the foundation pit; The formula for calculating the horizontal displacement of any monitoring point k of the foundation pit is as follows: D=(D1+D2)/2; S=(S1+S2)/2; Among them, D1 is the horizontal displacement of the foundation pit reference point m of the vertical foundation pit side change, D2 is the horizontal displacement of the foundation pit reference point n of the vertical foundation pit side change, D is the average level of the vertical foundation pit side change of any monitoring point k of the foundation pit Displacement, S1 is the horizontal displacement of the foundation pit reference point m parallel to the side of the foundation pit, S2 is the horizontal displacement of the foundation pit reference point n parallel to the side of the foundation pit, S is the average level of the change of any monitoring point k of the foundation pit parallel to the side of the foundation pit Displacement; the calculation formulas of the horizontal displacement of the vertical foundation pit edge change of the foundation pit reference points m, n and the horizontal displacement of the foundation pit reference point m, n parallel foundation pit edge change are as follows: D1=(L1cosα-L1′cosα′); D2=(L2cosβ-L2'cosβ'); S1=(L1sinα-L1'sinα'); S2=(L2sinβ-L2'sinβ').

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