CN106524989B - Large-scale foundation pit support deformation automatic analysis system and data analysis method - Google Patents
Large-scale foundation pit support deformation automatic analysis system and data analysis method Download PDFInfo
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- CN106524989B CN106524989B CN201611154201.2A CN201611154201A CN106524989B CN 106524989 B CN106524989 B CN 106524989B CN 201611154201 A CN201611154201 A CN 201611154201A CN 106524989 B CN106524989 B CN 106524989B
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Abstract
The invention discloses an automatic analysis system and a data analysis method for deformation of a large foundation pit support body, and belongs to the field of foundation pit engineering. The foundation pit supporting body is a reinforced concrete beam, and a supporting body model which has the same cross section, the same reinforcing bars and the same concrete proportion as the foundation pit supporting body and is poured simultaneously is arranged on a construction site. The data monitoring and analyzing system comprises a first steel bar meter, a first concrete strain meter, a second steel bar meter, a second concrete strain meter and an intelligent monitoring platform. The intelligent monitoring platform can correspondingly decompose the stress and the strain of the monitored foundation pit support body into load stress, temperature stress and shrinkage stress and data such as load strain, temperature strain, shrinkage strain and creep strain by utilizing the monitored data. Therefore, the technical scheme disclosed by the invention can accurately master the stress condition of the foundation pit supporting body, thereby providing safety guarantee for foundation pit construction.
Description
Technical Field
The invention relates to an automatic analysis system and a data analysis method for deformation of a large foundation pit support body, and belongs to the field of foundation pit engineering.
Background
In large-scale foundation pit engineering, a foundation pit supporting structure is of great importance. Reinforced concrete bearing structures are the more common foundation pit supporting structures. The support deformation and the support axial force are important bases for evaluating whether the supporting structure and the whole foundation pit project are safe or not.
At present, the deformation of a reinforced concrete supporting structure is mainly measured by arranging a concrete strain gauge in the supporting structure. However, the deformation of the reinforced concrete is influenced by a combination of load factors and non-load factors such as temperature change, concrete shrinkage and concrete creep. For example, the construction period of a large or ultra-large deep foundation pit project can reach 6 months or even longer, the maximum temperature difference of the support body structure can reach 30 degrees or even more, and the temperature deformation is an important factor to be considered. In addition, the support structure of large and ultra-large foundation pits is usually relatively long, and the shrinkage deformation caused by the concrete shrinkage is not negligible. Further, when a large axial pressure is applied, creep deformation of the support member is also considered.
However, in the conventional measurement of deformation, only the numerical value of the comprehensive deformation can be obtained, and the specific numerical values and the occupied proportions of load deformation, temperature deformation, shrinkage deformation, creep deformation and the like cannot be specifically known, so that when the deformation is large, the influence degree of each factor cannot be known, and effective countermeasures cannot be taken. Therefore, in order to better ensure the safety of the foundation pit construction in the large foundation pit construction, it is necessary to provide a novel deformation automatic analysis system and a data analysis method for the large foundation pit support.
Disclosure of Invention
The invention provides a deformation automatic analysis system and a data analysis method for a large foundation pit support body, aiming at the problems that specific values and occupied proportions of load deformation, temperature deformation, shrinkage deformation, creep deformation and the like in the foundation pit support body cannot be known specifically in the prior art, and effective countermeasures cannot be taken when the foundation pit support body is deformed greatly.
In order to solve the technical problems, the invention comprises the following technical scheme:
an automatic analysis system for deformation of a large foundation pit supporting body is characterized in that the foundation pit supporting body is a reinforced concrete beam, a supporting body model which has the same cross section, reinforcing bars and concrete proportion as the foundation pit supporting body is arranged on a construction site, the data monitoring system comprises,
the first steel bar meter is connected to the main bar of the foundation pit supporting body in series and used for measuring the comprehensive axial force F of the main bar of the foundation pit supporting body;
a second reinforcing bar meter connected in series to the main bar of the support body model for measuring the comprehensive axial force F of the main bar of the support body model Die ；
The first concrete strain gauge is arranged in the foundation pit supporting body and used for measuring the temperature t and the comprehensive strain epsilon of the foundation pit supporting body;
a second concrete strain gauge placed in the support body model for measuring the support body modelTemperature t Mould And combined strain epsilon Die ；
The intelligent monitoring platform comprises a data receiver, a data processor and a display; the data receiver is respectively connected with the first steel bar meter, the second steel bar meter, the first concrete strain gauge and the second concrete strain gauge and used for receiving measurement data F, F Die 、t、t Mould 、ε、ε Die (ii) a The data processor is connected with the data receiver, internally presets a calculation formula, and decomposes the comprehensive strain epsilon of the first concrete strain gauge into a temperature strain epsilon t Strain epsilon of load T Contraction strain ε P Creep strain ε c (ii) a The display is used for displaying the measurement data and the decomposition data of the measurement data.
Further, the calculation formula preset in the data processor comprises,
ε t ＝m·(t-t 0 )；
ε c ＝ε-ε t -ε T -ε P 。
wherein m is a temperature compensation coefficient and is a constant;
t 0 、t mold 0 -initial temperatures of the first and second concrete strain gauges, respectively;
E s 、A s respectively calculating the elastic modulus of the steel bar and the section area of the main bar connected with the first steel bar meter in series;
F T -load axial force for the first reinforcement gauge.
Further, the automatic analysis system for deformation of the support body of the large foundation pit according to claim 1,
the foundation pit supporting body is provided with q measuring points, main reinforcements at four directions, namely the upper, lower, left and right of a reinforcement cage at the cross section of each measuring point are respectively connected with a first reinforcement meter in series, and a first concrete strain meter is arranged at the center of the cross section of each measuring point;
s measuring points are selected on the support body model, a second steel bar meter is connected in series on the main bars in the upper, lower, left and right directions of the steel bar cage of the cross section of each measuring point, and a second concrete strain meter is arranged in the center of the cross section of each measuring point.
Preferably, the data processor further comprises a graphics output module.
Preferably, a concrete cushion is laid under the support model, and an isolation layer is laid between the support model and the concrete cushion.
Preferably, the isolation layer comprises a felt isolation layer, a lubricating grease and a felt isolation layer which are sequentially arranged from bottom to top.
Correspondingly, the invention also provides a data analysis method of the automatic analysis system for the deformation of the large foundation pit support, which comprises the following steps:
s1, binding a reinforcement cage of a foundation pit support body, selecting q measuring points, connecting a first reinforcement meter in series on main reinforcements of the reinforcement cage in four directions, namely the upper direction, the lower direction, the left direction and the right direction, of the cross section of each measuring point, and arranging a first concrete strain meter at the center of the cross section of each measuring point;
s2, binding a reinforcement cage of a support body model on a construction site, selecting S measuring points, connecting a second reinforcement meter in series on main reinforcements of the reinforcement cage in four directions, namely the upper direction, the lower direction, the left direction and the right direction, of the cross section of each measuring point, laying a second concrete strain meter at the center of the cross section of each measuring point, and pouring concrete required by a foundation pit support body and a support body model at the same time, so that the support body model and the foundation pit support body have the same cross-sectional shape reinforcement and concrete proportion;
s3, connecting the first steel bar meter, the first concrete strain meter, the second steel bar meter and the second concrete strain meter with an intelligent monitoring platform, and recording initial temperatures t of the first concrete strain meter and the second concrete strain meter 0j 、t Modulus 0h Wherein:
t 0j the initial temperature of the jth measuring point of the foundation pit support body, j belongs to [1, q ]]；
t Modulus 0h Temperature data h epsilon [1, S ] of the ith measuring point of the support body model on the ith day]；
S4, the intelligent monitoring platform respectively calculates the comprehensive axial force F of the first reinforcing steel bar meter ij And the comprehensive strain epsilon of the first concrete strain gauge ij Monitoring the temperature t ij And the combined axial force F of the second reinforcing bar meter Model i And the comprehensive strain epsilon of the second concrete strain gauge Die ih Monitoring the temperature t Die ih ；
Wherein, F ij The average axial force of each first steel bar meter at the jth measuring point of the foundation pit supporting body at the moment i;
ε ij the comprehensive deformation of the jth measuring point of the foundation pit supporting body at the moment i;
t ij the monitoring temperature of the jth measuring point of the foundation pit supporting body at the moment i;
F mold i The average axial force of all second steel bar meters at each measuring point of the support body model at the moment i;
ε die ih The comprehensive deformation of the jth measuring point of the support body model at the moment i;
t die ih The monitoring temperature of the h measuring point of the support body model at the moment i;
s5, comprehensive strain epsilon of j measuring point of foundation pit supporting body at moment i ij Decomposition to temperature strain
Strain of load
Strain of contraction
Creep strain
The method comprises the following steps:
s5-1, calculating the temperature strain of the j measuring point of the foundation pit support body at the moment i
S5-2, calculating the load strain of the j measuring point of the foundation pit support body at the moment i
Wherein:
s5-3, calculating the shrinkage strain of the j measuring point of the foundation pit supporting body at the moment i
S5-4, calculating creep strain of a j measuring point of the foundation pit support body at the moment i
Wherein m is a temperature compensation coefficient;
E s 、A s the modulus of elasticity of the bar and the breakage of the main bar in series with the first bar meterArea of the face.
Further, S6, after the step S5, the temperature strain of the jth measuring point on the foundation pit supporting body on the ith day is measured
Strain of load
Strain of contraction
Creep strain
Transformation into temperature deformation
Deformation under load
Shrinkage deformation
Creep deformation
The calculation is as follows:
wherein l j The length of the foundation pit support body related to the measuring point j is taken as the length of the foundation pit support body related to the measuring point j; total length of foundation pit support
Further, the method for measuring the temperature compensation coefficient m in step S5 includes the steps of:
s5-1: concrete shrinkage strain of mixed support model after 90 days
Tend to be stable and the strain epsilon of the concrete is measured Mould Mainly due to temperature strain
Inducing, selecting N characteristic test moments, and measuring the strain data epsilon of the nth characteristic test moment of the concrete Modulus nj 、t Die nj Fitting a temperature compensation coefficient m by linear regression, wherein m is poly (t) Modulus nj ,ε Modulus nj 1); wherein N is an element of [1, N ∈]。
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects: the automatic analysis system and the data analysis method for the deformation of the large foundation pit support body can decompose monitored strain data into temperature strain, load strain, shrinkage strain and creep strain, clearly know specific numerical values and growth proportions of all strains, accurately reflect the actual stress condition of the foundation pit support body in foundation pit construction, monitor the deformation data of the foundation pit support body in real time and provide guarantee for safe construction of a foundation pit.
Drawings
Fig. 1 is a block diagram of a system for automatically analyzing deformation of a support body of a large foundation pit according to a first embodiment of the present invention;
FIG. 2 is a diagram of measuring point arrangement of a foundation pit support according to a second embodiment of the present invention;
FIG. 3 is a schematic structural view of a support model;
FIG. 4 is a cross-sectional view of measurement point 1' in FIG. 3;
FIG. 5 is a schematic view of a second reinforcement bar gauge of the present invention connected in series with a reinforcement bar;
fig. 6 is a flow chart of a data analysis method of an automatic analysis system for deformation of a support body of a large foundation pit according to a third embodiment of the present invention;
fig. 7 is a graph showing the change of the comprehensive deformation of each monitoring point of the foundation pit support body according to the fourth embodiment of the invention with time;
fig. 8 is a graph showing the deformation of the foundation pit support according to the fourth embodiment of the present invention.
The numbers in the figures are as follows:
a foundation pit support 100; a first rebar meter 110; a first concrete strain gauge 120; a support body model 200; a second rebar meter 210; the main ribs 211; a second concrete strain gauge 220; a concrete pad 230; an isolation layer 240; an intelligent monitoring platform 300; a data receiver 310; a data processor 320; a graphics output module 321; a display 330.
Detailed Description
The automatic analysis system and the data analysis method for deformation of the support body of the large foundation pit provided by the invention are further described in detail with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent when considered in conjunction with the following description and claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
Example one
Referring to fig. 1, fig. 1 is a block diagram of a system for automatically analyzing deformation of a support body of a large foundation pit according to the present embodiment. The foundation pit supporting body 100 is a reinforced concrete beam, and a supporting body model 200 which has the same cross section, the same reinforcing bars and the same concrete mark number as the foundation pit supporting body 100 and is poured at the same time is arranged on a construction site. The deformation automatic analysis system of the foundation pit supporting body comprises a plurality of first steel bar gauges 110, a first concrete strain gauge 120, a second steel bar gauge 210, a second concrete strain gauge 220 and an intelligent monitoring platform 300. The first steel bar meter 110 is connected in series to the main bar of the foundation pit support 100 and is used for measuring the comprehensive axial force F of the main bar of the foundation pit support 100; the first concrete strain gauge 120 is arranged in the foundation pit supporting body 100 and used for measuring the temperature t and the comprehensive strain epsilon of the foundation pit supporting body 100; a second reinforcing bar meter 210 connected in series to the main bar of the support body model 200 for measuring the comprehensive axial force F of the main bar of the support body model 200 Die (ii) a A second concrete strain gauge 220 mounted in the support body model 200 for measuring the temperature t of the support body model 200 Die And combined strain epsilon Die (ii) a Intelligent monitoring platform 300, including data receiver 310, data processor 320 and display330; the data receiver 310 is respectively connected to the first steel bar meter 110, the first concrete strain gauge 120, the second steel bar meter 210, and the second concrete strain gauge 220 for receiving the measurement data F, F Die 、t、t Die 、ε、ε Die (ii) a The data processor 320 is connected with the data receiver 310, and internally presets a calculation formula to decompose the comprehensive strain epsilon of the first concrete strain gauge 120 into temperature strain epsilon t Strain epsilon of load T Contraction strain ε P Creep strain ε c (ii) a The display 330 is used for displaying the monitoring data and the decomposition data of the measurement data.
In a preferred embodiment, the calculation formula preset in the data processor comprises,
ε t ＝m·(t-t 0 )；
ε c ＝ε-ε t -ε T -ε P 。
wherein m is a temperature compensation coefficient and is a constant;
t 0 、t mold 0 -initial temperatures of the first and second concrete strain gauges, respectively;
E s 、A s respectively the elastic modulus of the steel bar and the section area of the main bar connected with the first steel bar meter in series;
F T axial force of load for the first reinforcement gauge, F T ＝F-F Die 。
It should be noted that the first steel bar meter 110 is connected withThe second reinforcing bar meter 210 is only used for indicating the position difference, and the structure and the working principle are the same. At present, the reinforcing bar meter is all through series connection on the main muscle of component, and frequency data is counted to the reinforcing bar through the reinforcing bar of gathering, and the axial force that a certain reinforcing bar receives is converted out, and concrete formula is:
wherein, F s Measuring the corresponding axial force for the reinforcing steel bar; f. of 0 Is the initial frequency; f. of i Real-time frequency; and k is a reinforcing steel bar gauge coefficient.
The aforementioned combined axial force F, F Die Are converted by the frequency data of the first and second reinforcing bar meters 110 and 210. The influence factors of the measured value of the reinforcing bar meter can be divided into load factors and non-load factors, wherein the non-load factors mainly comprise temperature and concrete shrinkage, the influence of concrete creep on the reinforcing bar meter can be ignored, and in addition, the axial load does not act on the support model 200, so the axial load force of the support model is not considered. Thus, F includes the temperature axial force F t Shrinkage axial force F P Load axial force F T And F is Die Including only temperature axial force
Force of contracting shaft
And under the conditions of same section structure, simultaneous pouring and similar environmental conditions,
therefore, the load axial force F of the foundation pit support in the formula T Is optionally F T ＝F-F Die 。
Note that since the reading of the first concrete strain gauge 120 is affected by a load factor and non-load factors such as temperature, concrete shrinkage, and concrete creep, the total strain ∈ is equal to ∈ t +ε T +ε P +ε c (ii) a Second concrete strain gauge, no axial loadCreep strain under axial load
Very small and therefore negligible, and therefore
Preferably, the data processor 320 further includes a graph output module 321 for plotting and presenting a graph of the change of the strain and deformation of the foundation pit support 100 with time. Therefore, the stress and strain conditions of the foundation pit supporting body can be known more conveniently and more intuitively.
Example two
Compared with the first embodiment, the preferred implementation mode is that q measuring points are arranged on the foundation pit supporting body 100, the main reinforcements at the upper, lower, left and right directions of the reinforcement cage at the cross section of each measuring point are respectively connected with a first reinforcement meter 110 in series, and a first concrete strain meter 120 is arranged at the center of the cross section of each measuring point; s measuring points are selected on the support body model 200, main reinforcements at four directions, namely the upper, the lower, the left and the right of a reinforcement cage at the cross section of each measuring point are respectively connected with a second reinforcement meter 210 in series, and a second concrete strain meter 220 is arranged at the center of the cross section of each measuring point. And taking the average value of the four first reinforcing steel bar meters on each measuring point as the stress of the foundation pit supporting body 100 on the measuring point, and taking the average value of the four second reinforcing steel bar meters on each measuring point as the stress of the supporting body model 200 on the measuring point. This arrangement can monitor the stress and the strain data of each measurement point on the foundation pit support 100 more comprehensively and more reasonably. As further described below with reference to fig. 2-5.
Fig. 2 is a measurement point layout diagram of a foundation pit support provided in this embodiment, and excavation of a foundation pit is performed by adopting layered and partitioned excavation, and a foundation pit support 100 is provided. In the figure, a foundation pit supporting body 100 is of a reinforced concrete structure, a main beam with the length of 220m is selected, and 10 measuring points are selected to monitor the foundation pit supporting body 100, wherein the measuring points are C1-C10 respectively. The measuring points are selected in a mode that a foundation pit supporting body 100 is supported by longitudinal columns, measuring points, such as measuring points C1 and C10, are arranged on the foundation pit supporting body between the two columns and close to a column fulcrum 1/3; measuring points such as measuring points C2 and C3, measuring points C5 and C6 and measuring points C8 and C9 are arranged on two sides of the construction joint; and (4) selecting measuring points at the intersection of the foundation pit supporting body, such as measuring points C4 and C7.
Fig. 3 is a schematic structural diagram of the support model 200 in fig. 2, where the support model 200 and the foundation pit support 100 have the same cross section, the same reinforcing bars, the same concrete ratio, and the same temperature and humidity environment, and are cast together with the foundation pit support 100. By way of example, the support body model 200 is 4m long, and measuring points 1 'and 2' are respectively arranged at positions 1m and 3m away from one end, and each measuring point is provided with a second steel bar gauge 210 and a second concrete strain gauge 220. Wherein, the bottom of the support body model 200 is provided with a C15 concrete cushion 230 with the thickness of 10cm, an isolation layer 240 is arranged between the support body model 200 and the cushion 230, and the isolation layer 240 sequentially comprises a felt isolation layer, a lubricating grease and a felt isolation layer from top to bottom. The even cushion layer 230 is arranged, so that the support body model 200 can be prevented from being stressed unevenly on soft soil, and the isolation layer 240 can reduce the influence of the cushion layer 230 on the temperature and the shrinkage effect of the support body model 200.
Fig. 4 is a cross-sectional view of the measuring point 1 'in fig. 3, which is illustrated by a cross-sectional view of the measuring point 1' in fig. 3, since the cross-sections of the measuring points are identical. The main reinforcements close to the middle part in the upper, lower, left and right directions of the reinforcement cage of the support body model 200 are respectively connected with 1 second reinforcement meter 210 in series, the reinforcement stress meters 210 are used for monitoring the stress data of each main reinforcement, and the average value of the four second reinforcement meters 210 is taken as the stress of the measuring point 1'; a second concrete strain gauge 220 is arranged at the center of the reinforcement cage close to the cross section, and the concrete strain gauge 220 is used for monitoring strain data and temperature data of the support body model. Since fig. 4 is a cross-sectional view, the main rib is only shown as a circular dot, for better explaining the connection manner of the second steel bar meter 210 and the main rib, please refer to fig. 5, fig. 5 is a schematic view of the connection manner of the second steel bar meter 210 and the main rib 211 in series, two ends of the second steel bar meter 210 are respectively welded on the two main ribs 211 and are connected with the two main ribs 211 in series.
EXAMPLE III
Referring to fig. 6, fig. 6 is a flow chart of a data analysis method of an automatic analysis system for deformation of a large foundation pit support according to the present invention, and the data analysis method is further described with reference to fig. 1 to 5. The data analysis method comprises the following steps:
s1, binding a reinforcement cage of a foundation pit supporting body 100, selecting q measuring points, connecting a first reinforcement meter 110 in series on reinforcements at four directions, namely an upper position, a lower position, a left position and a right position, of the reinforcement cage at the cross section of each measuring point, and arranging a first concrete strain meter 120 at the center of the cross section of each measuring point. Wherein, the model of the first reinforcement meter 110 matches with the size of the main reinforcement. As an example, as shown in fig. 2, a total of 10 measuring points, i.e., q is 10, are provided on the foundation pit support 100. The first reinforcing bar meter 110 may be disposed at a joint of two main bars, or one main bar may be broken and then the first reinforcing bar meter 110 may be welded at the notch.
S2, binding a reinforcement cage of the support body model 200 on a construction site, selecting S measuring points, connecting a second reinforcement meter 210 in series on reinforcements at the upper, lower, left and right directions of the reinforcement cage of each measuring point cross section, arranging a second concrete strain gauge 220 at the center of each measuring point cross section, and pouring concrete required by the foundation pit support body 100 and the support body model 200 at the same time, so that the support body model 100 and the foundation pit support body 200 have the same section shape and reinforcing bars. As an example, as shown in fig. 3, a total of 2 measurement points are provided on the support body model 200, i.e., S equals 2. In a construction site, the support model 200 and the foundation pit support 100 have substantially the same environment, and the difference in the external environment is eliminated as much as possible. A concrete cushion 230 is laid under the support model 200, an isolation layer 240 is arranged between the support model 200 and the cushion 230, and the isolation layer 240 sequentially comprises a felt isolation layer, lubricating grease and a felt isolation layer from top to bottom.
S3, connecting the first steel bar meter 110, the first concrete strain gauge 120, the second steel bar meter 210 and the second concrete strain gauge 220 with the intelligent monitoring platform 300, and recording the initial temperature t of the first concrete strain gauge 120 and the initial temperature t of the second concrete strain gauge 220 0j 、t Modulus 0h . Wherein: t is t 0j Is a groupInitial temperature of j measuring point of pit support body, j is belonged to [1, q ]]；t Modulus 0h Temperature data h e [1, S ] of the measurement points of the support body model h at the moment i respectively]. In engineering, a vibrating wire type steel bar stress meter is often adopted as the steel bar stress meter. The embedded concrete strain gauge is commonly used in engineering, the frequency is used as an output signal, and the anti-interference capability is strong; a temperature sensor is arranged in the temperature sensor to correct the temperature of the change caused by the influence of the external temperature; and a calculation chip is arranged in each sensor, and the measurement data is automatically converted to directly output the physical quantity. The first steel bar meter 110, the first concrete strain gauge 120, the second steel bar meter 210 and the second concrete strain gauge 220 are led out through leads, and the other ends of the leads are connected with the intelligent monitoring platform 300; when the wireless transmission and receiving module is arranged, a wireless transmission mode can also be adopted.
The time i is a certain measurement time, which may be selected manually, or may be a certain time in a preset manner, for example, a preset time interval of one hour is read to analyze the comprehensive strain.
S4, the intelligent monitoring platform 300 respectively calculates the comprehensive axial force F of the first steel bar meter 110 ij And the combined strain epsilon of the first concrete strain gauge 120 ij Monitoring the temperature t ij And the combined axial force F of the second reinforcing bar gauge 210 Mold i And the comprehensive strain epsilon of the second concrete strain gauge Die ih Monitoring the temperature t Die ih . Wherein: f ij Average axial force of each first reinforcing steel bar meter at j measuring point of foundation pit support body at moment i ij For the comprehensive deformation of the jth measuring point of the foundation pit supporting body at the moment i, t ij Monitoring temperature of jth measuring point of foundation pit supporting body at moment i, F Mold i Average axial force of all second reinforcing bar meters at each measuring point of the support body model at moment i, epsilon Die ih For the integrated deformation of the support body model at the j th measuring point at the i moment, t Die ih And i, monitoring the temperature of the h measuring point of the support body model.
It should be noted that 4 first steel bar meters 110 are arranged at each measuring point of the foundation pit support 100, so that the axial force is integrated
F ijn The nth first reinforcing bar meter 110 is the measuring point, and the reinforcing bar comprehensive axial force is converted by frequency. The support body model 200 has S measuring points, and each measuring point is provided with 4 second reinforcing steel bar meters 210, so that
S5, comprehensive strain epsilon of j measuring point of foundation pit supporting body 100 at moment i ij Decomposition to temperature strain
Strain of load
Strain of contraction
Creep strain
The method comprises the following steps:
s5-1, calculating the temperature strain of the j measuring point of the foundation pit supporting body 100 at the moment i
S5-2, calculating the load strain of the j measuring point of the foundation pit support body at the moment i
Wherein:
s5-3, calculating the shrinkage strain of the j measuring point of the foundation pit support body at the moment i
S5-4, calculating creep strain of a j measuring point of the foundation pit support body at the moment i
Wherein m is a temperature compensation coefficient; e s 、A s -the modulus of elasticity of the reinforcement and the cross-sectional area of the reinforcement, respectively.
Wherein, formula F T ＝F-F Die 、ε＝ε t +ε T +ε P +ε c 、
The description is given in the first embodiment, and is not repeated here.
By the embodiment, the comprehensive strain epsilon of a j measuring point of the foundation pit support body at the moment i ij Automatically decomposing into temperature strain through intelligent monitoring platform
Strain of load
Strain of contraction
Creep strain
The strain data of the foundation pit supporting body 100 can be monitored in real time, and the proportion of all factors in the strain data in the comprehensive strain can be clearly masteredEffectively reducing comprehensive strain provides basis.
In order to reflect the deformation of the foundation pit support 100 more intuitively, it is necessary to convert the strain data into deformation data. Preferably, the method further includes, after the step S5, step S6: the temperature strain of the jth measuring point on the foundation pit supporting body on the ith day
Strain of load
Strain of contraction
Creep strain
Transformation into temperature deformation
Deformation under load
Shrinkage deformation
Creep deformation
The calculation formula is as follows:
wherein l j The length of the foundation pit support body related to the measuring point j is taken as the length of the foundation pit support body related to the measuring point j; total length of foundation pit support
By way of example, as shown in fig. 2, the measuring points are 10, i.e. P equals 10, the length l involved in measuring point 1 1 The distance from one end of the foundation pit support body to the midpoint of the measuring point 1 and the measuring point 2 is measured; one side of the measuring point 2 is a construction joint, and the measuring point 2 is involvedAnd length l of 2 The distance from the midpoint of the measuring points 1 and 2 to the measuring point 2.
Further, the temperature compensation coefficient m in step S5 is a constant, and is obtained by: (1) the temperature compensation coefficients of the support body models with the same section, the same reinforcing bars and the same concrete mark are also similar, so the temperature compensation coefficients calculated in the prior engineering can be referred. (2) The method can be obtained by a measuring mode, and the measuring method comprises the following steps: after 90 days the concrete shrinkage strain epsilon of the support body model 200 Modulo p Tend to be stable and the strain epsilon of the concrete is measured Die Mainly due to temperature strain epsilon Modulus t Inducing, selecting N characteristic test days, measuring the strain data epsilon of concrete on the nth day Modulus nj 、t Modulus nj Fitting a temperature compensation coefficient m by linear regression, wherein m is poly (t) Modulus nj ,ε Modulus nj 1); for example, in the constructed support body model 200, as shown in fig. 3 and 4, the m values of the measuring points 1 'and 2' measured in the method (1) are 3.318 and 3.602, respectively, and the average value is 3.46.
Example four
Referring to fig. 7 and 8, fig. 7 is a graph showing the time-dependent change of the comprehensive deformation of each monitoring point of the foundation pit support provided in this embodiment, and fig. 8 is a graph showing the time-dependent change of the comprehensive deformation, load deformation, creep deformation, temperature deformation, and shrinkage deformation of the foundation pit support provided in this embodiment.
In the construction, 10 monitoring points are arranged on a foundation pit supporting body, and the arrangement of each monitoring point is shown in figure 2. Figure 7 shows a graph of the deformation of the length of the foundation pit support body related to each measuring point with time, and the maximum deformation of the measuring point can reach 12.5 mm. As shown in FIG. 8, the total deformation of the foundation pit support was about 60mm at days 68 and 86-89, the maximum load deformation occurred at about 30mm at day 60, the maximum creep deformation was about 22mm, the maximum temperature deformation was about 16mm, and the maximum shrinkage deformation was about 4mm over the entire length of the foundation pit support.
In summary, in the present invention, the support model 200 having the same cross section, the same reinforcement, and the same concrete ratio as the foundation pit support 100 is cast in the construction site, and the first steel bar meter 110, the first concrete strain gauge 120, the second steel bar meter 210, and the second concrete strain gauge 220 connected to the monitoring-only platform 300 are respectively disposed in the foundation pit support 100 and the support model 200, so that the monitored comprehensive deformation data is decomposed into load deformation, creep deformation, temperature deformation, shrinkage deformation, and the like. The automatic analysis system and the data analysis method for the deformation of the large foundation pit support body can clearly reflect the influence of load factors and non-load factors such as temperature, concrete creep and concrete shrinkage on the foundation pit support body 100, can provide a basis for pertinence reduction of comprehensive strain, thereby providing safety guarantee for foundation pit construction, and have the advantages of simple structure and convenience in construction.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (8)
1. An automatic analysis system for deformation of a large foundation pit support body is characterized in that the foundation pit support body is a reinforced concrete beam, a support body model with the same cross section, the same reinforcing bars and the same concrete proportion as the foundation pit support body is arranged on a construction site, the automatic analysis system for deformation comprises,
a first steel bar meter connected in series with the main bar of the foundation pit support body and used for measuring the comprehensive axial force of the main bar of the foundation pit support bodyF；
A second reinforcing bar meter connected in series to the main bar of the support body model for measuring the comprehensive axial force of the main bar of the support body modelF Die ；
A first concrete strain gauge arranged in the foundation pit supporting body and used for measuring the temperature of the foundation pit supporting bodytAnd combined strainε；
A second concrete strain gauge placed in the support body model for measuring the temperature of the support body modelt Die And combined strainε Die ；
The intelligent monitoring platform comprises a data receiver and dataA processor and a display; the data receiver is respectively connected with the first steel bar meter, the second steel bar meter, the first concrete strain gauge and the second concrete strain gauge and used for receiving measurement dataF、F Die 、t、t Die 、ε、ε Die (ii) a The data processor is connected with the data receiver, internally presets a calculation formula and converts the comprehensive strain of the first concrete strain gauge into a strain valueεDecomposition to temperature strainε t Strain of loadε T Shrinkage strainε P Creep strainε c (ii) a The display is used for displaying the measurement data and the decomposition data of the measurement data;
the calculation formula preset in the data processor comprises,
wherein the content of the first and second substances,mis a constant temperature compensation coefficient;
t 0 、t mold 0 -initial temperatures of the first and second concrete strain gauges, respectively;
E s 、A s respectively the elastic modulus of the steel bar and the section area of the main bar connected with the first steel bar meter in series;
F T -load axial force for the first rebar meter.
2. The automatic analysis system for deformation of the support body of the large foundation pit according to claim 1,
the foundation pit supporting body is provided withqThe measuring points are characterized in that main reinforcements at four directions, namely the upper direction, the lower direction, the left direction and the right direction of a reinforcement cage at the cross section of each measuring point are respectively connected with a first reinforcement meter in series, and a first concrete strain meter is arranged at the center of the cross section of each measuring point;
selecting on the support modelSAnd the main reinforcements at the upper, lower, left and right directions of the reinforcement cage at the cross section of each measuring point are respectively connected with a second reinforcement meter in series, and the center of the cross section of each measuring point is provided with a second concrete strain meter.
3. The system of claim 1, wherein the data processor further comprises a graphical output module.
4. The automatic analysis system for deformation of the support body of the large foundation pit according to any one of claims 1 to 3, wherein a concrete cushion layer is laid under the support body model, and an isolation layer is laid between the support body model and the concrete cushion layer.
5. The system for automatically analyzing the deformation of the support body of the large foundation pit according to claim 4, wherein the isolation layer comprises a felt isolation layer, a lubricating grease and a felt isolation layer which are arranged from bottom to top in sequence.
6. The data analysis method of the automatic analysis system for the deformation of the support body of the large foundation pit according to any one of claims 1 to 5, wherein the data analysis method comprises the following steps:
s1, binding the reinforcement cage of the foundation pit support body, selectingqThe measuring points are characterized in that main reinforcements at four directions, namely the upper direction, the lower direction, the left direction and the right direction of a reinforcement cage at the cross section of each measuring point are respectively connected with a first reinforcement meter in series, and a first concrete strain meter is arranged at the center of the cross section of each measuring point;
s2, binding reinforcement cages of the support body model on the construction site, and selectingSThe main reinforcements of the upper, lower, left and right directions of the reinforcement cage of the cross section of each measuring point are respectively connected with a second reinforcement meter in series, a second concrete strain gauge is arranged at the center of the cross section of each measuring point, and concrete required by a foundation pit supporting body and a supporting body model is poured at the same time, so that the supporting body model and the foundation pit supporting body have the same section shape reinforcement and concrete proportion;
s3, connecting the first steel bar meter, the first concrete strain gauge, the second steel bar meter and the second concrete strain gauge with an intelligent monitoring platform, and recording the initial temperature of the first concrete strain gauge and the initial temperature of the second concrete strain gauget j0 、t hMold 0 Wherein:
t j0 for foundation pit supportsjThe initial temperature of the point of measurement,j∈[1,q]；
t hmold 0 -isiTime support modelhThe initial temperature of the point of measurement,h∈[1,S]；
s4, the intelligent monitoring platform respectively calculates the comprehensive axial force of the first steel bar meterF ij And the combined strain of the first concrete strain gaugeε ij Monitoring the temperaturet ij And the combined axial force of the second reinforcing bar meterF iMould And the comprehensive strain of the second concrete strain gaugeε ihDie Monitoring the temperaturet ihDie ；
Wherein the content of the first and second substances,F ij is-toiFoundation pit support body at any momentjMeasuring the average axial force of each first steel bar meter of the point;
ε ij -isiFoundation pit support body at any momentjComprehensive deformation of the measuring points;
t ij -isiFoundation pit support body at any momentjMonitoring temperature of a measuring point;
F idie -isiThe average axial force of all second steel bar meters at each measuring point of the support body model at any moment;
ε ihdie Is-toiTime support model 1hComprehensive deformation of the measuring points;
t ihdie -isiTime support model 1hMonitoring temperature of a measuring point;
s5, williFoundation pit support body at any momentjIntegrated strain of measuring pointε ij Decomposition to temperature strain
Strain of load
Shrinkage strain
Creep strain
The method comprises the following steps:
s5-1, calculatingiFoundation pit support body at any momentjTemperature strain of measuring point
，
；
S5-2, calculatingiFoundation pit support body at any momentjLoad strain of measuring point
Wherein:
s5-3, calculatingiFoundation pit support body at any momentjShrinkage strain of measuring point
，
S5-4, calculatingiFoundation pit support body at any momentjCreep strain at measurement point
，
Wherein the content of the first and second substances,mis a temperature compensation coefficient;
E s 、A s respectively the elastic modulus of the steel bar and the section area of the main bar connected with the first steel bar meter in series;
7. The data analysis method of the automatic analysis system for deformation of the large foundation pit support according to claim 6, further comprising, after step S5,
s6, will beiThe upper part of the foundation pit supporting bodyjTemperature strain of measuring point
Strain of load
Shrinkage strain
Creep strain
Transformation into temperature deformation
Deformation under load
And shrinkage deformation
Creep deformation of
The calculation is as follows:
wherein the content of the first and second substances,l j for measuring pointsjThe length of the foundation pit support body; total length of foundation pit support
。
8. The data analysis method for the automatic analysis system of the deformation of the support body of the large foundation pit according to claim 6 or 7, wherein the temperature compensation coefficient in step S5mThe measuring method comprises the following steps:
s5-1-1: concrete shrinkage strain of support body model after 90 days
Tend to be stable and measure concrete strainε Die Mainly due to temperature strain
Cause, selectNAt the moment of characteristic test, measuring concretenStrain data of individual characteristic experimental timeε njDie 、t njDie Fitting the temperature compensation coefficient by linear regressionmWherein, in the step (A),m=polyfit(t njdie ,ε njDie 1); whereinn∈[1,N]。
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