Defect detection method for variable cross-section cast-in-place pile, computer device and storage medium

Abstract

The application discloses a simple and efficient defect detection method for a variable cross-section cast-in-place pile, computer equipment and a storage medium. The defect detection method for the variable cross-section cast-in-place pile comprises the following steps: acquiring model data, wherein the model data comprises a pile foundation length, a pile foundation diameter, specific heat capacities, thermal conductivities and densities of concrete and a surrounding rock-soil body, and a hydration heat curve of the concrete in an adiabatic state; calculating a calculated value of a temperature at a measuring point where a temperature sensor is to be installed in the pile foundation from the model data; the two sections of pile bodies of the pile foundation are each provided with a measuring point; comparing a difference between a measured value and the calculated value of the temperature at the measuring point with a preset error threshold value, and if the difference exceeds the error threshold value, it is determined that the pile foundation has a defect at the measuring point.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of variable cross-section cast-in-place piles, in particular to a variable cross-section cast-in-place pile defect detection method, a computer device and a storage medium. BACKGROUND

[0002] Cast-in-place piles are widely used in bridge engineering due to their large bearing capacity and strong adaptability. Due to the limitations of geological conditions and engineering difficulties, the application of variable cross-section cast-in-place piles has increased. Compared with traditional cast-in-place piles, variable cross-section cast-in-place piles have the following advantages: the variable cross-section can utilize part of the soil (rock) layer as a bearing layer, thereby enhancing its bearing capacity; and compared with cast-in-place piles of the same diameter, the amount of concrete used is reduced. However, due to the existence of variable cross-section, the construction of such pile foundations is more complex than that of general cast-in-place piles, which will increase the construction risk. Therefore, it is particularly important to ensure the construction quality of variable cross-section pile foundations.

[0003] Due to the uncertainty of geological conditions and the complexity of construction, defects such as cavities, broken piles, necking, bulging, and mud inclusion may occur during the construction of cast-in-place piles. Since pile foundations are deeply buried underground and have strong concealment, the above defects are difficult to be discovered in the early stage of construction. Once the pile foundation is formed, it needs to be repaired in a timely manner, which will cost a lot of manpower, material resources and financial resources. The stress characteristics of variable cross-section pile foundations change at the variable cross-section, so they are more prone to the above defects.

[0004] Currently, there are mainly the following types of defect detection methods for cast-in-place piles: low-strain detection method, high-strain detection method, drilling core method, and acoustic wave projection method. The first two methods mainly use sensors to receive dynamic response signals (such as displacement, acceleration, etc.) at the top of the pile. The pile-soil system responds dynamically under the action of power, based on the wave theory of one-dimensional rods, and through certain mathematical analysis of the measured signals, the integrity of the pile structure is determined. The drilling core method mainly uses a drilling machine (usually with an inner diameter of 10 mm) to take core samples from the pile foundation. According to the core samples, the length of the pile foundation, the concrete strength, the thickness of the pile bottom sediment, and the bearing layer conditions can be clearly judged. The acoustic wave transmission method is to embed several acoustic measuring pipes in the cast-in-place pile before pouring concrete, which serves as the channel for the ultrasonic pulse emission and reception probe. The ultrasonic probe measures the acoustic parameters of the ultrasonic pulse passing through each cross-section along the longitudinal axis of the pile. Then, these measured values are processed using various specific numerical criteria or visual judgments to determine the location of the pile defects and the integrity of the pile.

[0005] However, these traditional defect detection methods have difficult problems to solve in practice: first, high (low) strain detection is easily affected by the surrounding environment, and has low sensitivity to small defects, and cannot obtain the horizontal position information of the defect; second, for cast-in-place piles, it is difficult to calculate the elastic modulus by high (low) strain detection, resulting in inaccurate calculation of pile length and defect depth. The drilling core method is limited by one hole, and the judgment of local defects and horizontal cracks of the pile foundation is not necessarily very accurate, and it itself damages the pile foundation; when the acoustic wave transmission method is used for detection, the detected pile needs to be pre-buried with a sound measuring pipe, which increases the cost of the pile foundation, and can only detect defects between the contact pipes, has a certain blind area, and is not easy to detect horizontal small cracks, and this method cannot be applied to unhardened concrete piles, increasing the detection time. Therefore, the traditional pile foundation detection method has limitations.

[0006] In recent years, the use of the temperature field of cast-in-place piles to detect concrete defects has become a development trend, but it is still not suitable for detecting defects of variable cross-section cast-in-place piles. For example, Chinese invention patent CN104727357B discloses a method for detecting and repairing defects of a cast-in-place pile, but this method needs to pre-leave holes in the cast-in-place pile for placing the heating body used for detection before detection, and then fill the holes with concrete after detection, which is time-consuming and laborious. Chinese invention patent CN113026829B discloses a cast-in-place pile integrity detection device based on dense distributed fiber grating temperature sensing technology, which judges whether the concrete pouring is uniform, the pile diameter range and the pile body integrity according to the relative differences in pile body temperature at different plane positions and the amount of cast-in-place concrete, but this method is mainly used to judge the pile diameter distribution, and cannot judge the specific type and accurate position of the concrete defect of the pile foundation. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a simple and efficient defect detection method for variable cross-section cast-in-place piles, a computer device and a storage medium.

[0008] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a defect detection method for variable cross-section cast-in-place piles is provided, and the technical scheme is as follows:

[0009] The defect detection method for variable cross-section cast-in-place piles comprises the following steps:

[0010] Obtaining model data, the model data including the length of the pile foundation, the diameter of the pile foundation, the specific heat capacity, the thermal conductivity and the density of the concrete and the surrounding rock-soil body, and the hydration heat curve of the concrete in the adiabatic state;

[0011] The calculated value of the temperature at the measuring point where the temperature sensor is to be installed in the pile foundation is calculated from the model data; measuring points are arranged on both sections of the pile body of the pile foundation;

[0012] The difference between the measured value and the calculated value of the temperature at the measuring point is compared with a preset error threshold value, and if the difference exceeds the error threshold value, it is determined that the pile has a defect at the measuring point.

[0013] As a further improvement of the first aspect of the application, the error threshold value is ≤1℃; a pile-soil temperature field simulation model is established by using finite element calculation software according to the model data, and the calculated value of the temperature at the measuring point is output from the simulation model.

[0014] As a further improvement of the first aspect of the application, the pile-soil temperature field simulation model is established by using ABAQUS finite element software, wherein the radius of the surrounding rock-soil mass is 8-12 times the radius of the pile foundation, the surrounding rock-soil mass and the pile foundation are both set as cylinders, and DC3D8 solid heat transfer unit is used for calculation.

[0015] As a further improvement of the first aspect of the application, the temperature sensor is installed on the reinforcement cage; and / or the temperature sensor is three rows and is installed in the variable cross-section and the cross-section above and below the variable cross-section, respectively.

[0016] As a further improvement of the first aspect of the application, a temperature sensor is arranged on the vertical reinforcement of each cross-section; and three rows of temperature sensors are arranged on the variable cross-section and the cross-section within a range of 0.5m above and below the variable cross-section, respectively.

[0017] As a further improvement of the first aspect of the application, any of the following steps is further included:

[0018] On the same cross-section, if the difference between the measured value and the calculated value of N adjacent measuring points all exceeds the error threshold value, it is determined that the pile defect is located on the arc line passing through the N measuring points, and N≥2;

[0019] On the same longitudinal reinforcement, if the difference between the measured value and the calculated value of two adjacent measuring points both exceeds the error threshold value, it is determined that the pile defect is located between the two measuring points;

[0020] On two adjacent longitudinal reinforcements, if the difference between the measured value and the calculated value of four adjacent measuring points all exceeds the error threshold value, it is determined that the pile defect is located on the arc surface surrounded by the four measuring points;

[0021] If the difference between the measured value and the calculated value of the measuring point exceeds the error threshold value and the measured value is greater than the calculated value, it is determined that the defect at the measuring point is a bulge, and if the difference between the measured value and the calculated value of the measuring point exceeds the error threshold value and the measured value is less than the calculated value, it is determined that the defect at the measuring point is a necking.

[0022] As a further improvement of the first aspect of the application, the following steps are further included:

[0023] Step 100, connecting the measuring points with the difference between the measured value and the calculated value exceeding the error threshold with lines or surfaces to obtain the shape of the defect;

[0024] Step 200, assuming the size of the defect, and then modifying the simulation model according to the shape and size of the defect;

[0025] Step 300, comparing the calculated value of the new simulation model with the measured value; if there are still measuring points with the difference between the measured value and the calculated value exceeding the error threshold, repeating Step 200; if the difference between the measured value and the calculated value of all measuring points is less than the error threshold, entering Step 400;

[0026] Step 400, determining the position, type, shape and size of the defect according to the final simulation model.

[0027] In order to achieve the above-mentioned purpose, according to the second aspect of the present application, a computer device is provided, and the technical scheme is as follows:

[0028] The computer device comprises a memory and a processor; the memory is used for storing a computer program; and the processor is used for executing the computer program and realizing the defect detection method of the variable cross-section cast-in-place pile according to the first aspect when executing the computer program.

[0029] In order to achieve the above-mentioned purpose, according to the third aspect of the present application, a computer readable storage medium is provided, and the technical scheme is as follows:

[0030] The computer readable storage medium stores a computer program, and the computer program is executed by a processor to realize the defect detection method of the variable cross-section cast-in-place pile according to the first aspect.

[0031] Firstly, hydration heat is generated in the concrete pouring process, and the thermal conductivity of concrete is low, so the hydration heat generated is difficult to dissipate and is accumulated in the concrete. Therefore, the present application detects the defect of the variable cross-section cast-in-place pile by using the hydration heat of concrete, so that the defect of concrete can be found during the concrete pouring process, and timely measures can be taken for remediation, which is more convenient to operate, avoids detection and remediation after the pile is formed, and indirectly saves the construction period and cost.

[0032] Secondly, since the location, shape and size of the concrete defects (necking and bulging) have certain relevance with the amount of concrete, the amount of concrete largely determines the size of the hydration heat, and further affects the temperature field of the concrete. For the variable cross-section cast-in-place pile foundation, since there is a variable cross-section in the whole length of the pile body, the amount of concrete in the upper and lower parts of the variable cross-section is different, so the temperature field of the variable cross-section cast-in-place pile and the temperature field of the constant cross-section cast-in-place pile have great difference in distribution, and the existence of the concrete defects also has different influences on the temperature field distribution. Therefore, by analyzing the calculated value and the measured value of the temperature of the measuring point on the two sections of the pile body, the concrete defects of the variable cross-section cast-in-place pile can be more truly reflected.

[0033] Further, the present application does not cause damage to the pile foundation during detection, the detection process is simple and fast, and the position, type, shape and size of the concrete defects can be accurately detected, so that the staff can carry out targeted remediation, thereby significantly saving the construction period.

[0034] In summary, the defect detection method of the variable cross-section cast-in-place pile of the present application organically combines the pile foundation temperature field on-site monitoring and the simulation model, which not only has simple process and convenient operation, but also has high detection efficiency and accuracy, and makes up for the shortcomings of the existing physical detection technology, and can also significantly save the construction period and cost, and has strong practicability.

[0035] The present application will be further described below in conjunction with the drawings and specific embodiments. Additional aspects and advantages of the present application will be partially given in the following description, partially will become apparent from the following description, or will be understood by those skilled in the art through practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0036] The drawings forming a part of this application are used to aid in the understanding of the present application and the content provided by the drawings and the related description in the present application can be used to explain the present application, but do not constitute improper limitation on the present application. In the drawings:

[0037] Figure 1 It is a structural schematic view of the pile-soil temperature field simulation model in the first embodiment of the present application.

[0038] Figure 2 It is a 1 / 4 sectional view of the pile-soil temperature field simulation model in the first embodiment of the present application.

[0039] Figure 3 It is a side view of the temperature sensor distribution in the first embodiment of the present application.

[0040] Figure 4 It is a top view of the temperature sensor distribution at the variable cross-section in the first embodiment of the present application.

[0041] Figure 5 Fig. 1 is a schematic block diagram of an embodiment of the computer device of the present application.

[0042] Figure 6 Fig. 4 is a comparison chart of the measured values and the calculated values of the outer side measuring points on the cross section with a depth of 25 m in the application example. DETAILED DESCRIPTION

[0043] The present application will be described in detail below with reference to the drawings. Those skilled in the art will be able to implement the present application based on these descriptions. Before the present application is described in detail with reference to the drawings, it is particularly important to note that:

[0044] The technical solutions and technical features provided in each part of the present application, including the following description, can be combined with each other without conflict.

[0045] In addition, the embodiments of the present application involved in the following description are generally only embodiments of part of the present application, not all embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments in the present application without creative labor should belong to the scope of protection of the present application.

[0046] Regarding the terms and units in the present application. The terms "include", "have" and any variations thereof in the specification and claims of the present application and related parts are intended to cover non-exclusive inclusion.

[0047] The first embodiment of the defect detection method of the variable cross-section cast-in-place pile of the present application comprises the following steps:

[0048] Obtain model data, which includes the length and diameter of the pile foundation, the specific heat capacity, thermal conductivity and density of the concrete and the surrounding rock-soil body, and the hydration heat curve of the concrete in the adiabatic state;

[0049] Use a finite element calculation software to establish a pile-soil temperature field simulation model according to the model data, and output the calculated value of the temperature at the measuring point from the simulation model.

[0050] Compare and judge the difference between the measured value and the calculated value of the temperature at the measuring point with the preset error threshold value as follows to obtain the position and type of the defect:

[0051] (1) If the difference between the measured value and the calculated value of the temperature at a measuring point exceeds the error threshold value, it is determined that the pile foundation has a defect at the measuring point;

[0052] (2) On the same cross section, if the difference between the measured value and the calculated value of the temperature at N adjacent measuring points all exceeds the error threshold value, it is determined that the pile foundation defect is located on the arc line passing through the N measuring points, N≥2;

[0053] (3) On the same longitudinal steel bar, if the difference between the measured value and the calculated value of the two adjacent measuring points exceeds the error threshold value, it is determined that the pile foundation defect is located between the two measuring points;

[0054] (4) On the two adjacent longitudinal steel bars, if the difference between the measured value and the calculated value of the four adjacent measuring points exceeds the error threshold value, it is determined that the pile foundation defect is located on the arc surface surrounded by the four measuring points;

[0055] (5) If the difference between the measured value and the calculated value of the measuring point exceeds the error threshold value and the measured value is greater than the calculated value, it is determined that the defect at the measuring point is a bulge. If the difference between the measured value and the calculated value of the measuring point exceeds the error threshold value and the measured value is less than the calculated value, it is determined that the defect at the measuring point is a necking.

[0056] Wherein, the specific heat capacity, thermal conductivity and density of concrete and surrounding rock and soil in the model data can be obtained from the drilling columnar chart in the engineering geological survey report, but are not limited thereto. The radius and length of the concrete pile foundation can be obtained from the corresponding construction drawing. The hydration heat curve of the concrete in the adiabatic state is obtained from the paper "Hydration Heat Temperature Field of Large-Sized Concrete Member in Hardening Period" (Xue Sudo, Kang Guangbo, Li Xionghyan, et al. Journal of Beijing University of Technology, 2020, 46(2): 7). The initial temperature of the surrounding rock and soil can be obtained by the soil pressure cell with temperature measuring function previously placed on the inner wall of the drilling hole. The initial temperature of the concrete can be obtained by on-site measurement. The calculation duration is the time from the beginning of pouring to the final setting. It can be seen that the model data can be obtained by searching for information.

[0057] Specifically, the pile-soil temperature field simulation model is established according to the model data by using the ABAQUS finite element software, mainly including the following processes: before the simulation model is constructed by using the ABAQUS finite element software, Visual Studio and Intel Parallel Studio XE software need to be installed separately to realize the association of the fortran subprogram and the ABAQUS software. In the "component" module, a circular cross section is drawn according to the known radius of the concrete pile foundation on the drawing plane, and then the "stretching" method is used to stretch the circular cross section to a known length to form a cylinder. The construction process of the surrounding rock-soil body is the same as above, and the radius of the model surrounding rock-soil body is 10 times the radius of the concrete pile foundation to reduce the boundary effect. Then, the specific heat capacity, thermal conductivity and density of the concrete and the surrounding rock-soil body are set in the "property" module, and the concrete and the surrounding rock-soil body are respectively given; for the concrete, the "heat generation" attribute should also be additionally set in the "property" module. Next, the surrounding rock-soil body and the concrete are spliced together in the "assembly" module. Then, the calculation type is set to "heat transfer" in the "analysis step" module, and the calculation time is set to the time from the beginning of pouring to the final setting. The heat exchange between the concrete and the surrounding rock-soil body satisfies the fourth type of boundary condition, which is realized by using the "binding" condition in the "interaction" module. The initial temperatures of the concrete and the surrounding rock-soil body are set in the "load" module. In the "mesh" module, the concrete model and the surrounding rock-soil body model are meshed, and both of them are calculated by using the DC3D8 solid heat transfer unit.

[0058] Before the calculation starts, the hydration heat curve of the concrete in the adiabatic state is written into the fortran subprogram by using the Visual Studio software. After the writing is completed, the corresponding subprogram file is imported into the "general" part of the "job" module of the ABAQUS, and then the calculation is performed.

[0059] Figure 1 The structural schematic diagram of the pile-soil temperature field simulation model. Figure 2 The 1 / 4 sectional view of the pile-soil temperature field simulation model. As shown in Figures 1-2 , through the simulation model, the temperature calculation value of the concrete at any measuring point after different pouring times can be obtained.

[0060] The measured value of the temperature at the measuring point is collected by the temperature sensor and transmitted to the data collector through the cable, and then transmitted to the computer equipment by the data collector for analysis. Figure 3 The side view of the temperature sensor distribution. Figure 4 The top view of the temperature sensor distribution at the variable cross section. As shown in Figures 3-4As shown, the temperature sensors 400 are arranged in three rows and installed on the variable cross-section 200 and on the upper and lower sections of the variable cross-section 200, respectively. Temperature sensors 400 are also installed on the vertical reinforcing bars 300 of each section. Simulation results show that the concrete temperature field changes significantly within a 0.5m range above and below the variable cross-section 200, but beyond this range, the temperature field change is not significant. Therefore, it is preferable to place the temperature sensors 400 on the sections within a 0.5m range above and below the variable cross-section.

[0061] Preferably, the error threshold is 1°C.

[0062] Based on the first embodiment, the second embodiment of the defect detection method for variable cross-section cast-in-place piles of the present invention further includes the following steps:

[0063] Step 100: Connect the measurement points where the difference between the measured value and the calculated value exceeds the error threshold with lines or surfaces to obtain the shape of the defect;

[0064] Step 200: Assume the size of the defect, and then modify the simulation model according to the shape and size of the defect;

[0065] Step 300: Compare the calculated values ​​of the new simulation model with the measured values; if there are still measurement points where the difference between the measured values ​​and the calculated values ​​exceeds the error threshold, repeat Step 200; if the difference between the measured values ​​and the calculated values ​​of all measurement points is less than the error threshold, proceed to Step 400.

[0066] Step 400: Determine the location, type, shape, and size of the defects based on the final simulation model.

[0067] Figure 5 This is a schematic block diagram illustrating an embodiment of the computer device of the present invention.

[0068] like Figure 5 As shown, the computer device includes a processor 120 and a memory 110, with the memory 110 storing a computer program 111. When the computer program 111 is executed by the processor 120, the computer device can perform the steps of the defect detection method for variable cross-section cast-in-place piles as described in the above method embodiment. For specific implementation details, please refer to the method embodiment, which will not be repeated here.

[0069] The computer devices provided in the embodiments of the present invention may include, but are not limited to, smartphones, tablets, laptops, or desktop computers.

[0070] The processor 120 may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor 120 may be implemented using at least one hardware form selected from DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). The processor 120 may also include a main processor and a coprocessor. The main processor, also known as a CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 120 may further integrate a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor 120 may also include an AI (Artificial Intelligence) processor, which is used to handle computational operations related to machine learning.

[0071] The memory 110 may include one or more computer-readable storage media, which may be non-transitory. The memory 110 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In this embodiment, the memory 110 is used to store at least the following computer program 111, which, after being loaded and executed by the processor 120, is capable of implementing the relevant steps of the defect detection method for variable cross-section cast-in-place piles disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 110 may also include an operating system 112 and data 113, and the storage method may be temporary or permanent storage. The operating system 112 may include Windows, Unix, Linux, etc. The data 113 may include, but is not limited to, access data and hot data.

[0072] In some embodiments, the computer device may further include a display screen 130, an input / output interface 140, a communication interface 150, a power supply 160, and a communication bus 170.

[0073] Those skilled in the art will understand that Figure 5 The structures shown do not constitute a limitation on computer equipment and may include more or fewer components than illustrated.

[0074] It can be understood that if the defect detection method of the variable cross-section cast-in-place pile in the above embodiment is implemented in the form of a software function unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and performs all or part of the steps of the method of each embodiment of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), an electrically erasable programmable ROM, a register, a hard disk, a removable magnetic disk, a CD-ROM, a magnetic disk or an optical disk, and various media that can store program codes.

[0075] Based on this, the embodiment of the present application further provides a computer readable storage medium, and the computer readable storage medium stores a computer program. When the computer program is executed by a processor, the steps of the defect detection method of the variable cross-section cast-in-place pile are implemented. For specific implementation, please refer to the method embodiment, which will not be described here.

[0076] The functions of each functional module of the computer readable storage medium described in the embodiment of the present application can be realized according to the method in the above method embodiment, and the specific implementation process can refer to the related description of the above method embodiment, which will not be described here.

[0077] The defect detection method of the variable cross-section cast-in-place pile, the computer device and the storage medium provided by the embodiment of the present application are described in detail above. Each embodiment in the specification is described in a progressive manner, and each embodiment mainly describes the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other.

[0078] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in the present application specification can be realized by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been described in the above description. Whether the functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0079] The practicability and beneficial effects of the present application are illustrated by specific application examples below.

[0080] The total length of the pile is 70 m, of which the upper 25 m has a diameter of 2.8 m and the lower 45 m has a diameter of 2.2 m, i.e. the depth of the variable cross-section is 25 m. According to the distribution shown in Figure 3 and Figure 4 the cable temperature sensors are arranged on all longitudinal reinforcement at depths of 24.5 m, 25 m and 25.5 m, with 32 longitudinal reinforcements (16 on the inside and 16 on the outside) being evenly arranged at 25 m and 16 longitudinal reinforcements being evenly arranged at 24.5 m and 25.5 m.

[0081] The stratum conditions of the test site are as follows: 0-9.4 m is pebble, 9.4-70 m is fully weathered conglomerate; in addition, the groundwater level is 12.6 m, but it is all pumped out during drilling.

[0082] According to the borehole column chart in the engineering geological survey report of the test point, the specific heat capacity, thermal conductivity and density of the pile foundation concrete and each surrounding rock-soil body are obtained; the hydration heat curve of the concrete in the adiabatic state is θ(t) = θme -n / t , wherein θ(t) is the adiabatic temperature rise (°C) at the age t, θ is the final adiabatic temperature rise (°C), t is the age (h), and m and n are both constants.

[0083] Then, according to the obtained simulation data, a pile-soil temperature field simulation model is established by using the ABAQUS finite element software according to the model data, and it is assumed that the pile foundation has no any defects during modeling.

[0084] After the reinforcement cage is placed in place, the concrete is poured, and at the same time the data collector starts collecting temperature data.

[0085] The collected temperature measured values are transmitted into the computer equipment in real time, and compared with the calculation results of the simulation model.

[0086] Figure 6 The comparison chart of the measured values and the calculation values of the outer measuring points on the section with a depth of 25 m is shown in FIG. 4. As shown in FIG. 4, the measured values of the 16 measuring points on the outside are all higher than the calculation values by more than 2 °C, while the temperature difference of the measuring points on the inside and other sections is less than 0.5 °C, so it can be determined that there is a bulge defect on the section with a depth of 25 m. Connecting the 16 measuring points on the outside with a line, the defect shape at 25 m is a circular ring. Figure 6 Generally speaking, the necking and bulge width of the concrete pile foundation cannot exceed the design radius of the pile foundation (otherwise it becomes a broken pile defect), and the height of the necking and bulge is determined according to the calculation results of the temperature field. In this example, since only the temperature measured values of the measuring points at a depth of 25 m exceed the error threshold value, the height of the necking cannot exceed 1 m. Therefore, according to the simulation model, the defect shape at 25 m is a circular ring with a diameter of 2.8 m and a height of 1 m.

[0087] Figure 6 ​According to the data, the width of the defect on the cross section with a depth of 25 m is assumed to be 5 cm and the height is 4 cm, and then the simulation model is modified and recalculated. After repeated adjustment, when the width of the defect is 10 cm and the height is 7 cm, the difference between the calculated value and the measured value of each measuring point is less than the error threshold.

[0088] It should be understood that the terms used in this specification of the application only serve the purpose of describing specific embodiments and are not intended to limit the application. As used in this specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0089] It should also be understood that the term "and / or" used in the specification and the appended claims means one or more of the associated listed items as well as all possible combinations of the items and includes the combinations. It should be noted that in the specification of the application, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or system. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or system including the element.

[0090] The above-mentioned embodiment numbers of the application are only for description and do not represent the advantages and disadvantages of the embodiments. The above is only a specific implementation of the application, but the protection scope of the application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the application, and these modifications or replacements should be covered within the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

[0091] The above describes the relevant content of the application. The application specification applies specific examples to describe the principles and implementation modes of the application. The above description of the embodiments is only used to help understand the method of the application and its core idea. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the application, the application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A method for detecting defects in a variable cross-section cast-in-place pile, characterized in that: The method comprises the following steps: Obtaining model data, which comprises the length and diameter of the pile foundation, the specific heat capacity, thermal conductivity and density of the concrete and the surrounding rock-soil body, and the hydration heat curve of the concrete in the adiabatic state; Calculating the calculated value of the temperature at the measuring point of the temperature sensor to be installed in the pile foundation from the model data; the measuring point is arranged on two sections of the pile body of the pile foundation; Comparing the difference between the measured value and the calculated value of the temperature at the measuring point with a preset error threshold value; if the difference exceeds the error threshold value, it is determined that the pile foundation has a defect at the measuring point; The method further comprises any of the following steps: If the difference between the measured value and the calculated value of N adjacent measuring points on the same section exceeds the error threshold value, it is determined that the defect of the pile foundation is located on an arc line passing through the N measuring points, and N≥2; If the difference between the measured value and the calculated value of two adjacent measuring points on the same longitudinal reinforcement exceeds the error threshold value, it is determined that the defect of the pile foundation is located between the two measuring points; If the difference between the measured value and the calculated value of four adjacent measuring points on two adjacent longitudinal reinforcements exceeds the error threshold value, it is determined that the defect of the pile foundation is located on an arc surface surrounded by the four measuring points; If the difference between the measured value and the calculated value of the measuring point exceeds the error threshold value and the measured value is greater than the calculated value, it is determined that the defect at the measuring point is a bulge; if the difference between the measured value and the calculated value of the measuring point exceeds the error threshold value and the measured value is less than the calculated value, it is determined that the defect at the measuring point is a necking.

2. The method of claim 1, wherein: The error threshold value is ≤1℃; a pile-soil temperature field simulation model is established by using a finite element calculation software according to the model data, and the calculated value of the temperature at the measuring point is output from the simulation model.

3. The method for detecting defects of the variable cross-section cast-in-place pile according to claim 2, characterized in that: The ABAQUS finite element software is used to establish the pile-soil temperature field simulation model, wherein the radius of the surrounding rock-soil body is 8-12 times the radius of the pile foundation, the surrounding rock-soil body and the pile foundation are both set as cylinders, and the DC3D8 solid heat transfer unit is used for calculation.

4. The method of claim 2, wherein: The temperature sensor is installed on the reinforcement cage; and / or the temperature sensor is arranged in three rows and is installed on the variable cross-section and in the cross-section above and below the variable cross-section.

5. The method for detecting defects of the variable cross-section cast-in-place pile according to claim 4, characterized in that: The temperature sensor is installed on the vertical reinforcement of each cross-section; the three rows of temperature sensors are arranged on the variable cross-section and the cross-section within the range of 0.5m above and below the variable cross-section.

6. The method of claim 1, wherein: The method further comprises the following steps: Step 100, connecting the measuring points with the difference between the measured value and the calculated value exceeding the error threshold value by lines or surfaces to obtain the shape of the defect; Step 200, assuming the size of the defect, and then modifying the simulation model according to the shape and size of the defect; Step 300, comparing the calculated value of the new simulation model with the measured value; if there are still measuring points with the difference between the measured value and the calculated value exceeding the error threshold value, repeating Step 200; if the difference between the measured value and the calculated value of all the measuring points is less than the error threshold value, entering Step 400; Step 400, determining the position, type, shape and size of the defect according to the final simulation model.

7. Computer device, characterized in that The computer device comprises a memory and a processor; the memory is used for storing a computer program; the processor is used for executing the computer program and realizing the defect detection method of the variable cross-section cast-in-place pile according to any one of claims 1-6 when the computer program is executed.

8. A computer readable storage medium characterized by: The computer readable storage medium stores a computer program, wherein the computer program is executed by the processor to realize the defect detection method of the variable cross-section cast-in-place pile according to any one of claims 1-6.

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