CN104634785A - Novel concrete plane crack prediction, evaluation and graphical output method - Google Patents

Abstract

The invention discloses a method for evaluating and predicting the possible positions of surface cracks on a concrete plane through a three-dimensional deformation data model, which is established through three-dimensional laser scanning and a modeling technology. In the provided method, a concrete plane, which is needed to be monitored, is scanned by a three-dimensional laser scanner so as to obtain a three-dimensional data model; then deformation data is collected and fused for several times, the curvature is extracted and calculated, the cracked section judgment and critical section analysis are completed, finally a map of surface cracking degree distribution on a concrete flexural member is obtained, and thus the evaluation and prediction of surface crack and graphical output can be achieved. In the prior art, the cracks can only be detected artificially in a close distance after the cracks appear; the provided method can automatically predict the cracks in a remote distance without any contact in advance, and thus the structural safety hazards, which are caused by cracks, of a concrete flexural member are effectively eliminated.

Description

A kind of brand-new concrete plane FRACTURE PREDICTION assessment and Graphical output method

Technical field

The present invention relates in a kind of construction of structures the method assessed concrete surface and whether occur the position in the crack that crack and prediction thereof occur, the long-range non-contacting cracking situation to building concrete plane can be realized and detect.

Background technology

The degree that crack occurs is one of the important basic parameter of control structure security, stability, corrosion resistivity.Current, mostly slip-stick artist, to the crack of concrete construction of structures, is when crack is visible by naked eyes in certain distance, or just carries out measurement and detection work when there is large deformation, and then check it and whether meet designing requirement, and check that other may produce the reason in crack.This flaw detection knows aftersensation after being, the appearance that cannot fundamentally eliminate danger.

In addition; for many large-scale constructions of structures; as large-scale in large span floor, roof boarding, bridge, tunnel, concrete storage tank, containment vessel, tailing dam etc., tall and slender structure etc.; be difficult to the position realizing close-in measurement, the method for manual detection is obviously to meet the requirement it being carried out to Crack Monitoring.

And current stifled way is mainly adopted to this kind of distortion and Crack Monitoring method, namely moderate finite deformation (naked eyes Observable) is there is in bridge, tunnel etc., or instrument get unique point observation find moderate finite deformation time, slip-stick artist closely finds crack according to deformation position, and measures crack spacing and width.Because monitoring means is merely able to choose finite character point, adopt total powerstation or other measurement means spot measurements, the weak link therefore often later may caused danger in a large number.It knows aftersensation and locality to after the distortion of construction of structures, causes numerous structural safety hidden danger.

Summary of the invention

In order to solve above-mentioned prior art weak point, the present invention is mainly for the concrete component of bend in one direction, propose a kind of three-dimensional laser scanning technique that adopts to scan and modeling concrete component, thus the model data obtained is analyzed and calculates, the crack occurred can not only be determined, and the position that will occur crack can be predicted.

Three-dimensional laser scanning technique in the method, be considered to a revolutionary breakthrough of technical field of mapping after GPS space positioning system, have untouchable, rapidity, in real time, dynamically, initiatively, and high density, high precision, the characteristic such as digitizing, robotization, and be progressively used in engineering.Three-dimensional laser scanner, by scanning concrete surface, obtains intensive " some cloud ", thus the information acquisition of target object surface is got off.But because its precision be several millimeters to several centimetres not etc., can not directly obtain the crack lower than this precision.Therefore the data message of twice collection is needed to carry out matching, thus obtain the relative curvature of concrete component distortion, recycle a kind of theoretical method of backwards calculation, three dimensional point cloud information is oppositely deduced and obtains crack location, spacing and width information, or the degree in crack may be there is, and then draw cracking situation degree distribution figure, form the distortion of a kind of brand-new concrete surface and ftracture monitoring method and means.

The method is divided into following step:

1. initial condition data scanning: scan needing the original state of the plane predicting crack with three-dimensional laser scanner, the cloud data according to obtaining sets up three-dimensional model.Cracking situation in prediction relative deformation situation, then original state can be regarded as and not deform, and curvature is zero, can omit this step;

2. deformation state data scanning: the state when concrete plane is subject to certain effect of stress scans, obtains the 3 D deformation change of concrete plane;

3. curvature is extracted: the scan-data of step 1 and step 2 is inputted computing machine, carries out same coordinate system merge by a cloud number process software.In this time, the part that plane bends can present intuitively from three-dimensional model.Then curved surface cutting is carried out to the bending area of plane, the curvature that concrete surface each point is bending can be obtained.Whether the direction finding curvature maximum and cross section, next ftracture to this position and analyze.

4. calculate the tensile region average height of maximum curvature position: when concrete plane bends, convex surface can under tension, and concave surface can be under pressure, and has pulling force and pressure equilibrium that a face is subject in the middle of two faces, and we are referred to as neutral axis.Because cracking can occur in surface under tension, and whether we will calculate surface under tension and ftracture, and except knowing curvature, also need the height obtaining tensile region.First can calculate according to according to the parameter such as reinforcing bar configuration and concrete properties in cross section the average depth of compressive zone determining cross section, tensile region height is then the difference between concrete thickness and compressive region average height.

5. calculate the stretching strain of maximum curvature position: according to the tensile region height in the curvature obtained in step 3 and step 4, the two product can the mean strain ε on unit of account length inner concrete surface _{f, m};

6. according to concrete each parameter, the critical strain values ε of critical conditions when obtaining concrete cracking of tabling look-up _{t, k};

7. compare ε _{f, m}with ε _{t, k}size: 1. work as ε _{f, m}< ε _{t, k}, illustrate that concrete surface does not ftracture; 2. ε is worked as _{f, m}> ε _{t, k}concrete surface ftractures; 3. ε is worked as _{f, m}≈ ε _{t, k}, then maximum curvature position is cracking critical cross-section.

8. draw iso-curvature figure: according to the comparative result of step 7, extract Curvature Methods according in step 3, draw the iso-curvature figure of crack location, and draw iso-curvature figure at non-crack location, show the degree close to cracking.Finally, result is carried out images outputting.

Compared with the existing technology comparatively, its beneficial effect is patent of the present invention: realize crack long distance prediction, fracture is monitored; Existing spot measurement means revolutionary character is extended to subject surface bulk deformation to measure, eliminates because getting test leakage that point tolerance causes and surveying the estimation error and hidden danger that cause less; At a high speed, high-precision scanning means, the data processing method of robotization, realizes Real-Time Monitoring, exports during fructufy; Comprehensive color graphics represents, reaches visualize, patterned output effect; Realize possibility that prediction crack occurs and fracture interval and fracture width, the crack for concrete construction of structures occurs that the anticipation of position provides a kind of brand-new comprehensive monitoring and detection method; Improve operational security and efficiency, greatly reduce cost.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, the present invention is further described.

Fig. 1 is techniqueflow chart;

Fig. 2 is space three-dimensional cloud data figure;

Fig. 3 is that multi collect is with coordinate system process, profile curvature fusion figure;

Fig. 4 is subject to pure bending strip unit section figure, wherein 1. tensile regions, 2. neutral axis, 3. compressive region;

Fig. 5 is unit length 1m cross section pressurized figure, and wherein, a is cracking section, and b is non-cracking section, 1. tensile region, 2. compressive region, 3. reinforcing bar equivalent area.

Embodiment

The present invention is to concrete surface fracture predicting and draw cracking degree distribution plan implementation process as Fig. 1.Embodiment is as follows:

1. concrete surface 3-D data collection

1. original state 3-D data collection.Original state is generally the situation that concrete plane is not subject to too large external pressure, if concrete surface has produced larger distortion when measuring, original state can be assumed to perfect condition by us, and namely Deformation Curvature is zero.As follows to the process of 3-D data collection:

Needing the concrete surface carrying out Crack Monitoring to stick four positioning targets, the position of target is not point-blank.At the position placing three-dimensional laser scanning of concrete plane vis-a-vis, select optimum scanning position, then fix.Start three-dimensional laser scanner to scan, first three-dimensional laser scanner will carry out the scanning of cloud data, the color information of the concrete plane that then carries out taking pictures back.Just obtain initial condition data after three-dimensional laser scanner quits work, data are stored, obtain cloud data figure as shown in Figure 2.

2. deformation state 3-D data collection.After concrete plane receives effect of stress distortion, carry out the data acquisition of deformation state.Its detailed process and step are with 1. the same.

2. three dimensional point cloud process

The original state gathered in step 1 by three-dimensional laser scanner and the three dimensional point cloud of deformation state, import computing machine.Carry out same coordinate system by points cloud processing software to merge, so just obtain the three dimensional point cloud model of the relative distortion of concrete plane.

3. the extraction of curvature and calculating

Next, the three-dimensional model according to concrete surface carries out Surface Triangulation, and we can obtain the bending curvature that concrete surface follows point from subdivision graph.In the planes, the direction finding curvature maximum and cross section, carry out curve fitting to section being put cloud, and the curvature maximum of calculated curve, as shown in Figure 3.Same method obtains other profile curvatures and stores.

4. the calculating of tensile region average height

As shown in Figure 4 and Figure 5, the depth of compressive zone of unit length can be obtained by formula below:

h′＝h-h _c（1）

First the average depth of compressive zone h of per length section is determined _c.Compressive region cross section average height h _cby following formulae discovery:

$h_c=\frac{k_{1}d+k_{m}d}{2}---\left(2\right)$

Wherein, according to modular formula:

$k_1=\sqrt{{\left(\mathrm{\&rho;n}\right)}^2+2\mathrm{\&rho;n}}-\mathrm{\&rho;n}---\left(3\right)$

ρ is sectional reinforcement rate, reinforcing bar E _swith concrete E _cthe ratio of elastic modulus.K _mby following formulae discovery:

$b\&CenterDot;k_m\&CenterDot;d\frac{k_{m}d}{2}-b\&CenterDot;\frac{{(d-k_{m}d-\frac{\mathrm{\&phi;}}{2})}^2}{2}-n\&CenterDot;A_s\&CenterDot;(d-k_{m}d)-b\&CenterDot;c\&CenterDot;(d-k_{m}d+\frac{c}{2}+\frac{\mathrm{\&phi;}}{2})=0---\left(4\right)$

Parameters of formula sees the following form lattice 1:

Form 1

Letter	Name variable
		b	Cross-sectional width, gets 1m
c	Longitudinal reinforcement protective layer thickness
		d	Effective depth of section
kd	Compressive region significant height
		φ	Longitudinal reinforcement diameter
A s	Reinforcing bar equivalent area
		E c	Modulus of elasticity of concrete
E s	Reinforcing bar elastic modulus

5. calculate the mean strain ε of concrete surface _{f, m}

The concrete surface of unit length is due to bending produced stretching strain ε _{f, m}can be calculated by following formula:

ε _f，m＝h′k （5）

6. compare ε _{f, m}with ε _{t, k}size and cracking images outputting

ε _{t, k}what represent is this concrete concrete ultimate tensile strength, exceedes this numerical value and concrete surface will be caused to ftracture.We can obtain ε from concrete specification _{t, k}, and according to formula ε in this patent _t,k=h ' k is known, the critical buckling of cracking h ' calculates according to formula (1), and on the right side of equal sign, two amounts are known, therefore k _tcan calculate.

Next, ε is compared _{f, m}with ε _{t, k}size, following three kinds of situations will be there will be:

1. ε is worked as _{f, m}< ε _{t, k}time, illustrate that concrete surface does not ftracture, at this moment by maximum curvature k _maxposition mark out, show that these places are positions of most possible cracking;

2. ε is worked as _{f, m}≈ ε _{t, k}, represent that the maximum curvature position of concrete surface reaches the critical point of cracking, namely maximum curvature k _max≈ k _t, according to engineering monitoring requirement extract k _max, k ₁k _n, draw iso-curvature figure, export the degree schematic diagram of concrete surface close to cracking, and with reference to specification safety analysis, carry out the crack early warning of super rule.

3. ε is worked as _{f, m}> ε _{t, k}, according to the method for step 3, extract the curvature of concrete surface, successively decrease from being up to minispread by 10% and be followed successively by: k _max, k _max-10%k _{max-t, k}, k _{max-t, k}≈ k _t, be k by curvature _{max-t, k}position mark out, draw become iso-curvature figure, be the cracking figure of concrete surface.

Claims (4)

1. one kind brand-new based on three-dimensional laser scanning technique and three-dimensional point cloud modeling technique, reinforced concrete plane is carried out to the method for fracture predicting assessment and Graphical output, its technical method is: by 3 D laser scanning and modeling technique, obtains plane three-dimensional data model; By the fusion to twice (repeatedly) scan-data, obtain the deformation of concrete plane; Distorted pattern according to concrete plane carries out two-dimentional subdivision, extracts the bending curvature of plane each point; Calculate the table stretching strain with maximum deflection curvature position, and the maximum strain in this concrete specification contrasts, and predicts whether it ftractures; Finally by drafting concrete flexural member face checking degree distribution figure, realize visual picture and export.

2. the method according to right 1, it is characterized in that: obtain curvature by carrying out curved surface cutting to the concrete surface three-dimensional model merged, and therefrom find the maximum direction of curvature and cross section, carry out curve fitting to section being put cloud, and the curvature maximum of calculated curve.

3. method according to right 1, is characterized in that: by the calculating of Deformation Curvature and compressive region average height, whether analysis and prediction concrete surface ftractures, and its process and method are:

First the strain stress of this position concrete surface is calculated _{f, m}, unit length inner concrete surface is due to bending produced stretching strain ε _{f, m}can be calculated by following formula:

ε _f，m＝h′k （1）

Wherein k is the curvature measured according to 3-D scanning point cloud cutting plane, and h ' is tensile region, cross section height:

h′＝h-h _c（2）

H is for being subject to the concrete thickness in curved district, h _cit is compressive region cross section average height.Therefore, concrete surface stretching strain ε can be calculated from formula (1) and (2) _{f, m}.

Next, search from concrete specification and change concrete ultimate tensile strength ε _{t, k}, thus contrast ε _{f, m}and ε _{t, k}size: ε _{f, m}< ε _{t, k}, show not ftracture; ε _{f, m}≈ ε _{t, k}, be cracking critical conditions; ε _{f, m}> ε _{t, k}, then illustrate and ftractureed.

4. method according to right 1, it is characterized in that: the method exporting cracking degree gradient map is, to uncracked component, can directly export maximum curvature position, for reference as danger position information, and by drawing iso-curvature figure, reacting the position of concrete surface cracking intuitively and predicting that non-crack location closes on the degree of cracking.