CN115748841A - Karst region impact hole-forming cast-in-place pile deviation monitoring method - Google Patents

Abstract

The invention relates to the field of civil engineering construction monitoring, in particular to a karst region impact hole-forming cast-in-place pile deviation monitoring method, which comprises the following steps of constructing a BIM model of an impact hole-forming cast-in-place pile based on the diameter of a steel casing in a karst region construction site by utilizing a BIM modeling method; constructing a three-dimensional live-action model of a karst area construction site through unmanned aerial vehicle oblique photography; based on the same coordinate system, fusing the BIM model and the three-dimensional live-action model to obtain a fusion model, and measuring the horizontal distance between the impact cast-in-situ pile model and the steel casing model in the fusion model; and monitoring the deviation distance of the cast-in-situ bored pile in the karst area through the horizontal distance between the cast-in-situ bored pile model and the steel casing model. By adopting the scheme of the invention, the deviation degree of the position of the impact hole-forming cast-in-place pile in the karst area can be monitored at any time, the monitoring process is convenient, and the normal construction of the impact hole-forming cast-in-place pile is not influenced.

Description

A method for monitoring the displacement of perforated piles in karst areas

technical field

The invention relates to the field of civil engineering construction monitoring, in particular to a method for monitoring the displacement of perforated piles in karst areas.

Background technique

Reinforced concrete cast-in-place piles are the most commonly used foundations in bridge engineering. The code has strict regulations on the pile position, requiring that the offset of the bent pile is not greater than 50mm, and the limit offset is not greater than 100mm; the offset of the cap pile is not greater than 100mm. In karst areas, the most commonly used construction method for reinforced concrete pouring pile foundations is the percussion drilling method. The method is simple in equipment and low in cost, and is suitable for various covering layers. Combined with backfilling flakes and clay, it can conveniently and effectively treat karst caves, fissures, hemirocks and uneven karst phenomena, and has obvious advantages in terms of technology and economy. However, during pile foundation construction in karst development areas, extreme weather such as floods and heavy rains are often encountered, and the working environment is harsh. There is often an overburden layer on the rock layer. When the percussion hole-forming pile enters the rock and reaches the bottom of the cave, the drilling rig tends to the softer side due to the different hardness of the bottom surface of the pile hole. It needs to be repeatedly backfilled with rubble to correct it. At this time, the drilling rig is suspended. The steel wire rope is also biased to one side, and the pulling force of the steel wire rope gives a horizontal force to the drilling rig frame. When the covering layer supporting the drilling rig frame is weak, the horizontal deviation of the frame and the casing is prone to occur, resulting in the displacement of the punched cast-in-place pile. Although the deviation of the perforated cast-in-situ pile exceeds the allowable value of the specification, it does not often happen, but once it occurs, the treatment will be troublesome, and the construction period and cost will be increased.

For example, a highway bridge adopts bent piers, and there is an impact-holed cast-in-place pile foundation under each bent pier, and one of the impact-holed cast-in-place pile foundations was found to be deflected in the direction of the transverse bridge during the inspection process after the pile was completed. 15cm, 18cm deviation along the bridge direction, while the allowable value of the specification is 5cm, the deviation value is far beyond the allowable value of the specification, and finally the hole is re-impacted, affecting the construction period of 2.5 months. Another example is that the piers of a bridge in a certain city adopt cap pile foundations. Under each cap, 3 rows of perforated pile foundations are arranged in the direction of the bridge, and 4 rows of perforated pile foundations are arranged in the direction of the bridge. The rock surface of the bridge foundation is undulating. Vigorous, with strong karst development and bedrock covered with red clay. When excavating the foundation pit to test the pile foundation, most of the perforated pile foundation deflection exceeded the allowable value of the code, and the maximum deflection was 55 cm, far exceeding the allowable value of the code by 10 cm. Finally, the size of the cap was enlarged by 60 cm, which increased the project cost .

In summary, it is difficult to detect and discover the deviation of the pile foundation during the construction of the perforated piles. After the construction of the perforated piles is completed, the pile foundation detection process is often complicated to deal with, which affects the construction period, especially the overall impact. The construction period of the bridge increases the cost.

The most convenient way to deal with the deviation of the perforated piles in the karst development area is to monitor the displacement of the perforated piles during the construction process. , immediately backfill the rubble and concrete, re-bury the steel casing, and re-form the hole. However, the construction environment of bridge perforated piles is harsh. Manually measuring the displacement of the pile foundation during the process of perforating piles can only detect the diameter of the steel casing. The monitoring workload is large and the error is large, which affects the construction. Operation is difficult. In view of this, it is necessary to provide a new method for monitoring the displacement of percussive perforated piles in karst areas, so as to overcome the shortcomings of the existing technology.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for monitoring the deviation of the impact hole-forming pile in the karst area, which can monitor the deviation degree of the impact hole-forming pile position in the karst area at any time, and the monitoring process is convenient, and does not affect the impact of the hole-forming pile. Normal construction.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a method for monitoring the displacement of perforated piles in karst areas, comprising the following steps,

Step 1, using the BIM modeling method to construct the BIM model of the perforated pile based on the diameter of the steel casing in the construction site in the karst area;

Step 2, constructing a 3D real scene model of the construction site in the karst area through oblique photography of the UAV;

Step 3. Based on the same coordinate system, the BIM model is fused with the 3D real scene model to obtain a fused model, and the horizontal distance between the perforated pile model and the steel casing model is measured in the fused model ;

Step 4, monitoring the offset distance of the percussion perforation piles in the karst area through the horizontal distance between the perforation perforation pile model and the steel casing model.

The principle of the present invention is: build a BIM model of the impact hole-forming pile, use UAV oblique photography to build a three-dimensional real scene model of the construction site, fuse the two models in the same coordinate system, and measure the impact hole in the fusion model The horizontal distance between the cast-in-place pile model and the steel casing model is the displacement degree of the perforated pile in the karst area.

specific:

Step 1. Using the BIM modeling method, the BIM model of the perforated pile is constructed based on the diameter of the steel casing in the construction site in the karst area. The position of the BIM model of the perforated pile is the position required by the design. The impact-holed cast-in-place pile is a concealed project. In order to ensure the quality, the diameter of the steel casing is 20cm larger than the impact-holed cast-in-place pile, so the actual diameter of the impact-holed cast-in-place pile is also 20cm larger than its design diameter. The diameter of the BIM model of the perforated pile is taken as the diameter of the steel casing, so the diameter of the BIM model of the perforated pile is equal to the actual diameter of the perforated pile.

Step 2: Construct a 3D real scene model of the construction site in the karst area through oblique photography of the UAV. From the three-dimensional real-scene model, the position of the steel casing during the construction of the perforated pile can be measured, and the position of the steel casing at the end of the hole is the actual position of the perforated pile.

Step 3. Based on the same coordinate system, the BIM model is fused with the 3D real scene model to obtain a fused model, and the horizontal distance between the perforated pile model and the steel casing model is measured in the fused model ; Among them, the impact hole-forming cast-in-place pile model in the fusion model comes from the BIM model, and the steel casing model in the fusion model comes from the 3D real scene model;

Step 4, monitoring the offset distance of the percussion perforation piles in the karst area through the horizontal distance between the perforation perforation pile model and the steel casing model.

To sum up, the present invention can monitor the deviation between the actual hole-forming position and the designed position during the construction of the impact-hole-forming cast-in-situ pile.

The beneficial effects of the present invention are: adopting the displacement monitoring method of perforated piles in karst areas according to the present invention can monitor the deviation degree of the perforated piles in karst areas, and adopting oblique photography of unmanned aerial vehicle, the monitoring process is convenient, It does not affect the normal construction of perforated piles.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the specific process of constructing the BIM model of the percussive bored pile is as follows:

Use the intersection method in the Openroads designer software to draw the bridge plane line to get the bridge plane line;

Draw a profile on the bridge plane by entering the slope, station number, and vertical curve radius;

Import the plane line of the bridge with longitudinal section into OpenBridges Modeler software, and place the spanning line according to the number of bridge spans and distance;

Extract the custom template library file under the installation directory of the OpenBridges Modeler software into Miscrostation, and draw the impact hole-forming cast-in-place pile according to the diameter of the steel casing in Miscrostation; define the impact size by customizing the origin in the origin command The position where the bored pile is placed in the spanning line forms a three-dimensional BIM template for the impacted bored pile;

Place the 3D BIM template of the perforated pile in OpenBridges Modeler to obtain the BIM model of the perforated pile.

The beneficial effect of adopting the above-mentioned further solution is: for conventional bridges, Openroads designer and Miscrostation have ready-made templates, which can be modeled quickly. For special bridges, the model can be saved as a template for quick editing and repeated use.

Further, the diameter of the impact-forming cast-in-place pile in the BIM model is the diameter of the steel casing in the construction site, and the pile top elevation of the impact-forming cast-in-place pile in the BIM model is taken as the top surface elevation of the steel casing.

The beneficial effect of adopting the above-mentioned further scheme is that in actual construction, the diameter of the steel casing is about 20 cm larger than the design diameter of the perforated pile, and the elevation of the top of the casing is also greater than that of the perforated pile. In order to conveniently measure the horizontal distance between the perforated pile model and the steel casing model, in the BIM model, the diameter of the perforated pile is taken as the diameter of the steel casing, and the top elevation of the perforated pile is taken as The elevation of the top of the steel casing. The BIM model of the perforated pile is the same as the diameter and top elevation of the steel casing, which facilitates the integration of the BIM model and the 3D real-scene model to measure the deviation of the perforated pile.

Further, the specific process of constructing the 3D real scene model of the construction site in the karst area is as follows:

Arrange semi-permanent image control points around the construction site in the karst area;

According to the regional terrain and scope of the construction site and the endurance of the drone, plan the flight route and set the flight parameters;

Control the UAV equipped with a five-lens oblique photogrammetry camera to conduct field aerial surveys according to the flight route and flight parameters, and obtain aerial survey data with image control point images;

Based on aerial triangulation, 3D scene modeling is carried out according to aerial survey data, and a 3D real scene model of the construction site in the karst area is generated.

The beneficial effects of adopting the above-mentioned further scheme are: setting semi-permanent image control points, which can be used all the time in the construction stage; UAVs using five-lens oblique photogrammetry cameras conduct field aerial surveys according to flight routes and flight parameters, and obtain images with image control points. The aerial survey data of point image has high aerial survey efficiency, and the aerial survey of a bridge construction site can be completed in 10 minutes; the aerial triangulation survey has high calculation efficiency, and the modeling can be completed in a few hours.

Further, based on aerial triangulation, the specific steps for 3D scene modeling based on aerial survey data are as follows:

Obtain the same-named points between adjacent images according to the aerial survey data and perform image matching to obtain the parallax and depth information between adjacent images;

Based on the disparity and depth information between adjacent images, combined with the position and attitude information of the images, the aerial relationship between adjacent images is calculated using photogrammetry;

Based on the aerial relationship between adjacent images, all pixels in the image are discretized in three-dimensional space through dense image matching, and multiple discrete points with color information are obtained; multiple discrete points with color information in three-dimensional space Colored points form a colored point cloud;

Connect multiple discrete points in the color point cloud through the TIN triangular network method to form multiple triangular patches;

A triangular network is composed of multiple triangular patches, and the triangular network is used as the basic model;

According to the spatial position of the color point cloud point, the color information of the point is mapped to the surface of the basic model to obtain the initial 3D real scene model;

The initial 3D real scene model is refined and corrected to obtain a 3D real scene model of the construction site in the karst area.

The beneficial effects of adopting the above-mentioned further scheme are: due to problems such as aerial photography blind spots, ground object reflections and different aerial photography time, etc., resulting in hollow areas, texture deformation, model suspension, etc. It is inevitable to use the above method to repair the initial 3D real scene model.

Further, in the flight parameters, the degree of heading overlap is not less than 75%, and the degree of lateral overlap is not less than 60%. The UAV adopts close-in photogrammetry, and the flight height range is 15-40m.

The beneficial effect of adopting the above-mentioned further scheme is: the displacement limit of the pile foundation is 5cm or 10cm, so the accuracy of the oblique photography of the UAV is required to be high, and the plane accuracy of the oblique photography of the UAV is required to be about 2cm, so no one The drone adopts close-up photography, and the distance between the drone and the ground is 15m to 40m. The distance between the drone and the ground is less than 40m to take high-definition photos to ensure accuracy; On-site shooting security.

Further, based on the same coordinate system, the BIM model is fused with the 3D real scene model to obtain a fused model, and the horizontal distance between the perforated pile model and the steel casing model is measured in the fused model. The specific steps are,

Import the 3D real scene model of the construction site in the karst area into MicroStation in FBX format, and put the 3D real scene model of the construction site in the karst area and the BIM model of the perforated pile into the same coordinate space of MicroStation to obtain the fusion model;

Using the measurement function in MicroStation, the impact hole-forming pile model and the steel casing model in the fusion model are selected to measure the distance, and the horizontal distance between the impact hole-forming pile model and the steel casing model is obtained.

The beneficial effect of adopting the above-mentioned further scheme is that: both the BIM model and the 3D real-scene model of the steel casing can be queried for their respective horizontal position coordinates, but the size of the perforated pile is large, and its deviation limit is small, so the steel casing can Both fabrication errors and deformations can affect the horizontal position coordinates queried directly from the 3D reality model. Adopting the above-mentioned further scheme can ensure the accuracy of the horizontal distance between the perforated pile model and the steel casing model, and can also intuitively reflect the relative distance between the hole-forming position and the design position of the perforated pile.

Further, after monitoring the offset distance of the perforated piles in the karst area, select the corresponding treatment method at the construction site according to the offset distance between the perforated piles and the steel casing; specifically,

If the horizontal distance between the impact-forming cast-in-place pile model and the steel casing model is less than or equal to X1, when installing the impact-forming cast-in-place pile reinforcement cage, the center of the impact-forming cast-in-place pile reinforcement cage and the impact-forming hole Center alignment of cast-in-situ pile design;

If the horizontal distance between the perforated pile model and the steel casing model is in the range of (X1, X2], when installing the perforated pile reinforcement cage, the center of the perforated pile reinforcement cage will be impacted Deviated to the offset direction of the steel casing, the difference between the offset distance of the steel casing and X1 is taken as the distance between the center of the reinforced cage of the perforated pile and the center of the steel casing;

If the horizontal distance between the impact hole-forming cast-in-place pile model and the steel casing model is greater than X2, backfill rubble and clay and re-drill holes before installing the foundation reinforcement cage of the reinforced concrete pile;

Among them, X1 and X2 are preset values, X1 is half of the difference between the diameter of the steel casing and the design diameter of the perforated pile, and X2 is the sum of X1 and the allowable value of the pile foundation deviation.

The beneficial effect of adopting the above further scheme is that the deviation of the steel casing can be monitored in the process of forming the hole of the percussion hole-forming cast-in-place pile, and the deviation of the pile hole can be determined in time. Moreover, different treatment methods can be selected according to the horizontal distance between the impact hole-forming cast-in-place pile model and the steel casing model, which is economical and effective.

Further, when the allowable value of pile foundation deviation is 5cm, X1 and X2 are taken as 10cm and 15cm respectively; when the allowable value of pile foundation deviation is 10cm, X1 and X2 are taken as 10cm and 20cm respectively.

The beneficial effect of adopting the above-mentioned further scheme is: the permissible value of pile foundation displacement of bent pile and cap group pile foundation is different, and according to the permissible value of pile foundation displacement, X2 adopts different preset values, allowing the pile foundation to have a certain value smaller than that of the pile foundation. The displacement of the allowable value of the foundation deviation is in line with the principle of economy.

Description of drawings

Fig. 1 is the flow chart of a kind of karst area percussion perforation pile deflection monitoring method of the present invention;

Fig. 2 is a top view of the BIM model of the perforated pile and the three-dimensional real scene model of the construction site in the karst area;

Figure 3 is a schematic diagram of the displacement of the perforated pile and the steel casing.

Detailed ways

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

As shown in Figure 1, the method for monitoring the displacement of percussive perforated piles in the karst area of the present embodiment includes the following steps,

Step 1, using the BIM modeling method to construct the BIM model of the perforated pile based on the diameter of the steel casing in the construction site in the karst area;

Step 2, constructing a 3D real scene model of the construction site in the karst area through oblique photography of the UAV;

Step 3. Based on the same coordinate system, the BIM model is fused with the 3D real scene model to obtain a fused model, and the horizontal distance between the perforated pile model and the steel casing model is measured in the fused model ;

Step 4, monitoring the offset distance of the percussion perforation piles in the karst area through the horizontal distance between the perforation perforation pile model and the steel casing model.

Each step is described in detail below.

Construction of the BIM model of the perforated pile:

According to the design, first draw multiple irregular polygons and path curves in MicroStation, and then use commands such as stretching construction and placing paths to realize the construction of the BIM model of the perforated pile. In this embodiment, the Bentley series software is used to construct the BIM model of the perforated pile.

In this specific embodiment, the specific process of constructing the BIM model of the impact hole-forming cast-in-place pile is as follows:

(1) Use the intersection method in OpenRoads Designer software to draw the plane line of the bridge to obtain the plane line of the bridge; specifically, the drawing of the plane line of the bridge is realized by inputting three-point coordinates and curve elements.

(2) Draw the vertical section on the plane line, and complete it by inputting the slope, chainage and vertical curve radius.

(3) After the bridge plane line is drawn, import the bridge plane line with the vertical section into the OpenBridgesModeler software, and place the span line according to the number and distance of the bridge, so as to accurately locate the position of the impact-holed cast-in-place pile.

(4) Find the cel format file in the installation directory of the OpenBridges Modeler software, that is, the custom template library file, and extract the custom template library file into Miscrostation to establish a 3D BIM template for impact-holed cast-in-place piles. The method is to first obtain the diameter of the steel casing, draw the two-dimensional section of the perforated pile, and then stretch the section into a three-dimensional shape of the perforated pile by means of tensile structure; for simple regular shapes, it can be Draw directly by finding the corresponding regular body in the smart entity, such as a cylinder, which can be drawn directly by entering the diameter and height; the placed regular body can be one or more, if there are more than one, you only need to use Boolean The summation command combines various regular bodies into one body to realize the overall drawing of the perforated pile; then define the placement path by customizing the origin in the origin command, that is, the perforated pile template is placed on the layout Cross the position placed in the line, complete the template drawing and return to the Open bridges modeler to place the template of the perforated pile, and obtain the BIM model of the perforated pile.

In this specific embodiment, the diameter of the impact-forming cast-in-place pile in the BIM model is the diameter of the steel casing in the construction site, and the pile top elevation of the impact-forming cast-in-place pile in the BIM model is taken from the top surface of the steel casing elevation.

Before impacting the hole-forming cast-in-place pile, a steel casing needs to be buried to play the role of positioning, retaining wall and protecting the hole. The diameter of the steel casing is larger than the design diameter of the perforated pile, about 20cm larger. Therefore, the hole-forming diameter of the impact-forming cast-in-place pile is also 20 cm larger than the design diameter of the impact-forming cast-in-place pile. In this embodiment, when establishing the BIM model of the perforated perforated pile, the diameter of the perforated perforated pile is taken as the diameter of the steel casing, which is for the convenience of monitoring the deviation of the perforated pile foundation. In addition, during the construction of bridge engineering pile foundations, it is necessary to use artificial islands and build steel structure platforms as construction platforms. The top elevation of the steel casing is generally higher than the design elevation of the pile top. The design elevation of the top is taken as the elevation of the top of the steel casing, which is also for the convenience of monitoring the deviation of the hole formed by the pile foundation.

Construction of 3D reality model:

In this specific embodiment, the specific process of constructing the 3D real scene model of the construction site is as follows:

(1) Arrange semi-permanent image control points around the construction site; the image control points are in the survey area captured by using rtk or total station (rtk is used in most cases) during aerial survey of UAV The established iconic real coordinate points, through the image control points, can correct the coordinate points measured by the drone in the later stage, so as to complete the measurement of the drone. By uniformly arranging image control points on the construction site, the model can be matched with the real geodetic coordinates, and the accuracy of the model can be controlled.

(2) According to the regional topography and scope of the construction site and the endurance of the UAV, plan the flight route and set the flight parameters, such as flight height, course overlap and lateral overlap, etc.; the accuracy of UAV aerial survey needs to be less than 2cm , To this end, the following measures are taken: during the UAV aerial survey process, ensure that the heading overlap is not less than 75%, and the lateral overlap is not less than 60%; the UAV adopts close-in photogrammetry, and the height is 15m ~ 40m.

(3) Control the UAV equipped with a five-lens oblique photogrammetry camera to conduct field aerial surveys according to the flight route, and obtain aerial survey data with image control point images; among them, the aerial survey data includes aerial photos and GPS data obtained by the UAV , like control point data, etc.

(4) Based on aerial triangulation, 3D scene modeling is carried out according to aerial survey data, and a 3D real scene model is generated.

Aerial triangulation, also known as analytical aerial triangulation, refers to the use of photogrammetric analysis to determine the outer orientation elements of all images in an area. In traditional photogrammetry, this is achieved by measuring the point position, that is, according to the image point coordinates measured on the image and the geodetic coordinates of a small number of control points, the geodetic coordinates of the unknown points are obtained, so that the known points increase to There are no less than 4 in each model, and then use these known points to solve the outer orientation elements of the image, so analytical aerial triangulation is also called photogrammetric encryption or spatial three encryption.

The principle of generating a 3D real-scene model based on aerial triangulation is as follows: firstly, extract points with drastic changes in color or texture in the image (acquired by UAV), and call these points feature points; The same feature points that exist at different degrees to realize the feature information association of different photos; then adjust the camera internal parameters, position and attitude during imaging to minimize the error of feature points intersecting in three-dimensional space; adjust the camera position and attitude with aerotriangulation As the output, the image is matched pixel by pixel to generate a dense 3D point cloud; the triangulation network is constructed based on the 3D point cloud; finally, the photos taken with the triangular surface are found, and the best shooting angle is selected through certain rules. Color the triangles to generate a 3D reality model. In this specific embodiment: based on aerial triangulation, the specific steps of performing three-dimensional scene modeling according to aerial survey data are as follows:

Obtain the same-named points between adjacent images according to the aerial survey data and perform image matching to obtain the parallax and depth information between adjacent images;

Based on the disparity and depth information between adjacent images, combined with the position and attitude information of the images, the aerial relationship between adjacent images is calculated using photogrammetry;

Based on the aerial relationship between adjacent images, all pixels in the image are discretized in three-dimensional space through dense image matching, and multiple discrete points with color information are obtained; multiple discrete points with color information in three-dimensional space The colored points form a colored point cloud; the colored point cloud not only has the geometric characteristics of a point cloud, but also has color information for each point;

Connect multiple discrete points in the color point cloud through the TIN triangulation network to form multiple triangular patches;

A triangular network is composed of multiple triangular patches, and the triangular network is used as the basic model, which is the white model; according to the spatial position of the colored point cloud points, the color information of the points is mapped to the surface of the basic model to obtain the initial 3D real scene Model; mapping the color information of points to the surface of the basic model is to play the color attribute of the color point cloud, so that the initial 3D real scene model has both geometric appearance and real color texture.

Due to problems such as aerial photography blind spots, ground object reflections, and different aerial photography times, hollow areas, texture deformation, and model suspension appear in the 3D real-scene model. This is inevitable for real-scene 3D modeling based on oblique photography technology; , using DP-Model modeling software to refine and correct the defects existing in the initial 3D real-scene model, and delete pile machinery, excavators and other construction machinery to obtain the final 3D real-scene model, and the final 3D real-scene model The realistic model only includes the ground and steel casings.

Model fusion and ranging:

In this specific embodiment, Fig. 2 is a top view of the BIM model of the perforated pile and the three-dimensional real-scene model of the construction site in the karst area; The BIM models of bored piles are realized based on the wgs84 coordinate system; therefore, the fusion model is obtained by combining the BIM model with the 3D real scene model; The specific steps to determine the horizontal distance between cylinder models are:

Import the 3D real scene model into MicroStation in FBX format, and put the 3D real scene model and BIM model in the same coordinate space in MicroStation to obtain the fusion model;

Utilize the measurement function in MicroStation, select the model of perforated perforated pile in the fusion model and the steel casing model to measure the distance, obtain the horizontal distance between the model of perforated perforated pile and the model of steel casing, impact The deviation between the hole-forming cast-in-place pile and the steel casing is shown in Figure 3.

Offset monitoring:

In this specific embodiment, after monitoring the offset distance of the perforated pile in the karst area, the corresponding treatment is selected at the construction site according to the horizontal distance between the perforated pile model and the steel casing model. method; specifically,

If the horizontal distance between the impact-forming cast-in-place pile model and the steel casing model is less than or equal to X1, when installing the impact-forming cast-in-place pile reinforcement cage, the center of the impact-forming cast-in-place pile reinforcement cage and the impact-forming hole Center alignment of cast-in-situ pile design;

If the horizontal distance between the perforated pile model and the steel casing model is in the range of (X1, X2], when installing the perforated pile reinforcement cage, the center of the perforated pile reinforcement cage will be impacted Deviated to the offset direction of the steel casing, the difference between the offset distance of the steel casing and X1 is taken as the distance between the center of the reinforced cage of the perforated pile and the center of the steel casing;

If the horizontal distance between the impact hole-forming cast-in-place pile model and the steel casing model is greater than X2, backfill rubble and clay and re-drill holes before installing the foundation reinforcement cage of the reinforced concrete pile;

Among them, X1 and X2 are preset values, X1 is half of the difference between the diameter of the steel casing and the design diameter of the perforated pile, and X2 is the sum of X1 and the allowable value of the pile foundation deviation.

In this specific embodiment, when the allowable value of the pile foundation deviation is 5cm, X1 and X2 are respectively 10cm and 15cm; when the allowable value of the pile foundation deviation is 10cm, X1 and X2 are respectively 10cm and 20cm.

The present embodiment is described below with specific application examples:

Take the K114+600 Jiuxu Bridge of Pingnan Expressway as an example. The bridge span layout is 5×20m+4×20m+4×20m+5×20m. The covering layer in the substructure is medium expansive soil with a thickness of 10m-20m, and the underlying bedrock is strongly weathered limestone and moderately weathered limestone, with strong karst development. The piers of the Jiuwei Bridge are bent piers, and a reinforced concrete pile foundation is set under each bent pier, and the reinforced concrete pile foundation is constructed by impact hole forming. The diameter of the impact hole-forming cast-in-situ pile is 150cm.

Firstly, the BIM model of the percussive perforated piles of the bridge is established by using OpenBridge Modeler and Microstation software under the Bentley platform. The diameter of the BIM model of the perforated pile is taken as 170cm, and the top elevation of the BIM model of the perforated pile is taken as the top elevation of the steel casing.

Then, during the construction of perforated piles, the Phantom 4RTK multi-rotor UAV equipped with the RIY-D2M five-lens camera is used periodically to collect on-site information and data. The control point, the UAV flying height is 20m, the course overlap is 85%, the side overlap is 85%, and 2000 photos are obtained at a time. Context Capture software under Bentley platform is used to reconstruct the 3D real scene model, and the calculation time is about 6 hours each time. DP-Model software is used to refine and correct the defects existing in the initial 3D real scene model. At the same time, the pile work is also deleted. Machinery, excavators and other construction machinery can get the final 3D real scene model, as shown in Figure 2. It can be seen from Figure 2 that the model plane error is controlled within 2cm.

Then, the BIM model of the perforated pile is integrated with the 3D real scene model, and the offset distance between the perforated pile model and the steel casing model is measured. Specifically: first import the BIM model into the Microstation platform in DNG format, then export block grids in FBX format from the 3D real scene model established by Context Capture software, and then import them into the Microstation platform in the form of grids to complete the BIM model Integration with 3D reality models.

In the Microstation platform, measure the distance between the perforated pile model and the steel casing model, that is, the horizontal distance between the design plane position of the perforated pile and the steel casing, that is, the hole-forming distance of the perforated pile. Offset position, as shown in Figure 3.

It is qualified when the horizontal distance between the impact-forming cast-in-place pile model and the steel casing model is less than or equal to 5cm. When installing the reinforced concrete impact-forming cast-in-place pile reinforcement cage, for the convenience of construction, the center of the reinforcement cage can be connected with the Center alignment of steel casing;

When the horizontal distance between the impact hole-forming cast-in-place pile model and the steel casing model is greater than 5cm and less than or equal to 10cm, since the actual diameter of the impact-hole-forming cast-in-place pile is greater than the design diameter of 20cm, when the steel casing deviates by 10cm When the reinforcement cage is lowered and installed, the center of the reinforcement cage is aligned with the design center of the pile foundation, which can still ensure that the minimum protective layer thickness of the perforated pile is greater than 5cm;

The center of the reinforcement cage of the perforated pile is biased towards the offset direction of the steel casing, and the distance between the center of the reinforcement cage of the perforated pile and the center of the steel casing is taken as the difference between the offset distance of the steel casing and X1. The distance between the steel cage center of the cast-in-place pile and the design center of the impact-holed cast-in-place pile can meet the allowable value of pile foundation deviation;

When the horizontal distance between the impact-forming cast-in-place pile model and the steel casing model is greater than 15cm, although the actual diameter is greater than the design diameter of 20cm, the actual diameter of the impact-forming cast-in-place pile is greater than the design diameter of 20cm, but the impact cannot be guaranteed. The actual diameter of the bored pile is greater than the design diameter of 20cm. The center of the steel cage is located at the design center of the perforated pile. Therefore, it is necessary to backfill the flakes and clay and re-drill the holes.

Comparative example:

The geological conditions in the karst development area are complex. There are certain laws in the macroscopic view of karst caves, karst troughs, and fissures, but they are ever-changing in the microscopic view and have no rules to follow. The overburden above the bedrock also has a variety of geological conditions. Sometimes even the geological conditions of adjacent pile foundations of the same bridge are quite different, and the pile foundation is drilled once, so repeated tests cannot be done.

To verify the effect of this embodiment, take the Shuikou-Chongzuo-Aidian highway (the section from Chongzuo to Aidian, with a total length of 58.67 km) as an example. Shuikou-Chongzuo-Aidian Highway (Chongzuo-Aidian Section) has 8 bridges located in karst geological areas, namely: K1+343 Huipi Bridge (48 pile foundations), K4+180 Xiaqifeng Separation Overpass (20 pile foundations), K4+605 Qufeng No. 1 Bridge (48 pile foundations), K6+215 Quyang Viaduct Bridge (48 pile foundations), FK0+982.5 Ramp Bridge of Tianxi Hub Interchange (112 pile foundations ), Tianxi hub interchange GK0+551.5 ramp bridge (104 pile foundations), Tianxi hub interchange HK0+641.000 ramp bridge (44 pile foundations), IK4+992 Tingliang interchange IK4+992 ramp bridge (16 pile foundations ), there are a total of 372 pile foundations, all of which are perforated piles. The pile foundations of the above eight bridges started on December 19, 2020 and will be completed in October 2022. In June 2021, when inspecting the 100 pile foundations completed in the early stage, it was found that 2 pile foundations were displaced, one of which was offset by 15cm along the bridge, 20cm across the bridge, and the other 10cm along the bridge. In order to prevent subsequent pile foundation deviation accidents, the method of this embodiment will be adopted in July 2021, and all pile foundations will be completed by October 2022, and there will be no pile foundation displacement exceeding 5cm.

Therefore, this embodiment successfully solves the problem of displacement monitoring during the punching process of the pile foundation in the karst area. Now that the UAV has been used in highway construction, this embodiment will not increase the hardware expenditure, the cost is not high, and the accuracy requirement is met.

In the method for monitoring the displacement of perforated piles in karst areas in this embodiment, the BIM model of perforated piles is first constructed using the BIM modeling method; then the three-dimensional real scene model of the construction site is constructed through oblique photography of UAVs; and then The BIM model of the perforated pile and the three-dimensional real scene model are fused to obtain a fusion model, and the offset distance between the perforated pile and the steel casing is measured in the fusion model; finally, the perforated pile and the steel casing are measured The offset distance of the impact hole-forming pile in the karst area can be monitored for the deviation degree; the scheme of this embodiment can monitor the offset degree of the impact hole-forming pile position in the karst area at any time, and the monitoring process is convenient without affecting the impact cost. Normal construction of bored piles.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (9)

1. A method for monitoring the displacement of perforated piles in karst areas, characterized in that: comprising the following steps, Step 1, using the BIM modeling method to construct the BIM model of the perforated pile based on the diameter of the steel casing in the construction site in the karst area; Step 2, constructing a 3D real scene model of the construction site in the karst area through oblique photography of the UAV; Step 3. Based on the same coordinate system, the BIM model is fused with the 3D real scene model to obtain a fused model, and the horizontal distance between the perforated pile model and the steel casing model is measured in the fused model ; Step 4, monitoring the offset distance of the percussion perforation piles in the karst area through the horizontal distance between the perforation perforation pile model and the steel casing model. 2. The displacement monitoring method of perforated piles in karst area according to claim 1, characterized in that: the specific process of constructing the BIM model of perforated piles with percussion is as follows: Use the intersection method in the Openroads designer software to draw the bridge plane line to get the bridge plane line; Draw a profile on the bridge plane by entering the slope, station number, and vertical curve radius; Import the plane line of the bridge with longitudinal section into OpenBridges Modeler software, and place the spanning line according to the number of bridge spans and distance; Extract the custom template library file in the installation directory of the OpenBridges Modeler software into Miscrostation, and draw the cross-section of the perforated pile in Miscrostation according to the diameter of the steel casing; define it by customizing the origin in the origin command Impact the position of the hole-forming cast-in-place pile in the spanning line to form a three-dimensional BIM template for the impact-hole-forming cast-in-place pile; Place the 3D BIM template of the perforated pile in OpenBridges Modeler to obtain the BIM model of the perforated pile. 3. The method for monitoring the displacement of perforated piles in karst areas according to claim 1, characterized in that: the diameter of perforated piles impacted in the BIM model is the diameter of the steel casing in the construction site, and the In the BIM model, the elevation of the top surface of the steel casing is taken as the pile top elevation of the perforated pile. 4. the displacement monitoring method of perforated pile in karst area according to claim 1, characterized in that: the specific process of constructing the three-dimensional real scene model of the construction site in karst area is as follows: Arrange semi-permanent image control points around the construction site in the karst area; According to the regional terrain and scope of the construction site and the endurance of the drone, plan the flight route and set the flight parameters; Control the UAV equipped with a five-lens tilt photogrammetry camera, conduct field aerial surveys according to the flight route and flight parameters, and obtain aerial survey data with image control point images; Based on aerial triangulation, 3D scene modeling is carried out according to aerial survey data, and a 3D real scene model of the construction site in the karst area is generated. 5. The method for monitoring the displacement of perforated piles in karst areas according to claim 4, characterized in that: based on aerial triangulation, the specific steps of performing three-dimensional scene modeling according to aerial survey data are as follows: Obtain the same-named points between adjacent images according to the aerial survey data and perform image matching to obtain the parallax and depth information between adjacent images; Based on the disparity and depth information between adjacent images, combined with the position and attitude information of the images, the aerial relationship between adjacent images is calculated using photogrammetry; Based on the aerial relationship between adjacent images, all pixels in the image are discretized in three-dimensional space through dense image matching, and multiple discrete points with color information are obtained; multiple discrete points with color information in three-dimensional space Colored points form a colored point cloud; Connect multiple discrete points in the color point cloud through the TIN triangulation network method to form multiple triangular patches; A triangular network is composed of multiple triangular patches, and the triangular network is used as the basic model; According to the spatial position of the color point cloud point, the color information of the point is mapped to the surface of the basic model to obtain the initial 3D real scene model; The initial 3D real scene model is refined and corrected to obtain a 3D real scene model of the construction site in the karst area. 6. The method for monitoring the displacement of perforated piles in karst areas according to claim 4, characterized in that: in the flight parameters, the heading overlap is not less than 75%, the lateral overlap is not less than 60%, and no The man-machine adopts close-in photogrammetry, and the flying height is 15m~40m. 7. The method for monitoring the displacement of perforated piles in karst areas according to claim 2, characterized in that: based on the same coordinate system, the BIM model is fused with the three-dimensional real-scene model to obtain a fusion model, and in the The specific steps for measuring the horizontal distance between the impact hole-forming cast-in-place pile model and the steel casing model in the fusion model are as follows: Import the 3D real scene model of the construction site in the karst area into MicroStation in FBX format, and put the 3D real scene model of the construction site in the karst area and the BIM model of the perforated pile into the same coordinate space of MicroStation to obtain the fusion model; Using the measurement function in MicroStation, the impact hole-forming pile model and the steel casing model in the fusion model are selected to measure the distance, and the horizontal distance between the impact hole-forming pile model and the steel casing model is obtained. 8. The method for monitoring the displacement of perforated piles in karst areas according to claim 1, characterized in that: after monitoring the displacement distance of perforated piles in karst regions, according to the model of perforated piles with impact and The horizontal distance between the steel casing models selects the corresponding treatment method at the construction site; specifically, If the horizontal distance between the impact-forming cast-in-place pile model and the steel casing model is less than or equal to X1, when installing the impact-forming cast-in-place pile reinforcement cage, the center of the impact-forming cast-in-place pile reinforcement cage and the impact-forming hole Center alignment of cast-in-situ pile design; If the horizontal distance between the perforated pile model and the steel casing model is in the range of (X1, X2], when installing the perforated pile reinforcement cage, the center of the perforated pile reinforcement cage will be impacted Deviated to the offset direction of the steel casing, the difference between the offset distance of the steel casing and X1 is taken as the distance between the center of the reinforced cage of the perforated pile and the center of the steel casing; If the horizontal distance between the impact hole-forming cast-in-place pile model and the steel casing model is greater than X2, backfill rubble and clay and re-drill holes before installing the foundation reinforcement cage of the reinforced concrete pile; Among them, X1 and X2 are preset values, X1 is half of the difference between the diameter of the steel casing and the design diameter of the perforated pile, and X2 is the sum of X1 and the allowable value of the pile foundation deviation. 9. The method for monitoring the displacement of perforated piles in karst areas according to claim 8, characterized in that: when the allowable value of the displacement of the pile foundation is 5cm, X1 and X2 are respectively 10cm and 15cm; When the allowable value is 10cm, X1 and X2 are taken as 10cm and 20cm respectively.

Images