A building foundation pile safety monitoring system

Abstract

The application discloses a building foundation pile safety monitoring system, which is characterized by comprising a detection component arranged in parallel with a concrete foundation pile to be monitored, wherein the detection component is made of the same concrete material as the concrete foundation pile, a strain gauge is arranged in a monitoring depth position in the detection component, the strain gauge is connected to the detection component through a connecting line arranged in the detection component and connected to a control device, and the control device is connected to an alarm device. The application has the advantages of simple and feasible implementation, high monitoring reliability, strong practicability and the like, and can better monitor the safety of the building foundation pile in a saline environment under the influence of sulfate erosion.

Description

[0001] The present application is a divisional application of the patent application No. 202111498892.9, filed on December 9, 2021, for "Salt Environment Building Foundation Pile Safety Monitoring Method". TECHNICAL FIELD

[0002] The present application relates to the technical field of building structure safety monitoring, in particular to a building foundation pile safety monitoring system. BACKGROUND

[0003] The foundation pile is a supporting foundation for bearing of a building, usually refers to a single pile in a pile group foundation, and is generally made of cement concrete structure. Therefore, the structural strength of the foundation pile has a basic influence on the building safety. The concrete structure of the foundation pile will be subjected to sulfate corrosion in seawater, saline-alkali land, acid rain and other environments, resulting in structural damage and strength reduction. In the environment where sulfate exists, when the concrete is eroded or the pressure changes, cracks will be generated. Then, the sulfate will enter the interior of the concrete through the cracks, and then react with calcium hydroxide and hydrated calcium aluminate in the cement in the cracks to produce ettringite crystals, which will expand to about 100%. The ettringite crystals thus produced will cause the cracks to be stretched, making the cracks further expand and grow, so that the sulfate can further enter deeper positions, thus forming a vicious cycle, which will quickly reduce the strength of the concrete structure. The reduction of the strength of the foundation pile will directly affect the safety of the building. Therefore, for buildings in saline environments, it is necessary to monitor the structural strength changes of the foundation pile caused by sulfate corrosion to improve the safety of the building.

[0004] CN111310360A once disclosed a method for evaluating the damage transmission of concrete under sulfate corrosion in the splash zone, which can predict the damage of concrete under sulfate corrosion in the splash zone of marine environment, thereby providing a basis for durability analysis of concrete structure. However, the method obtains the evaluation results through theoretical analysis and calculation, has low uncertainty and poor practicability.

[0005] Therefore, how to better monitor the safety of the building foundation pile under the sulfate corrosion in the saline environment has become a method to be considered and solved by the person skilled in the art. SUMMARY

[0006] In view of the above deficiencies of the prior art, the technical problem to be solved by the present application is to provide a salt environment building foundation pile safety monitoring method which is simple to implement, has high monitoring reliability, is strong in practicability, and can better monitor the safety of the building foundation pile under the sulfate corrosion in the saline environment. The present application also discloses a building foundation pile safety monitoring system.

[0007] In order to solve the above technical problems, the present application adopts the following technical solutions:

[0008] A method for monitoring the safety of a building pile in a saline environment, characterized by embedding a stress sensor in a concrete structure constituting the building pile, detecting the expansion force of crystallization caused by a sulfate reaction at the front end of a crack in the concrete structure by the stress sensor to determine the depth of sulfate erosion, and issuing an alarm when the depth of erosion reaches an alarm line.

[0009] This is because the process of damage to the concrete structure caused by sulfate erosion is that when a crack is generated in the concrete structure, water vapor containing sulfate ions will naturally gather at the narrowest position at the front end of the crack and form a small reaction pool. The sulfate reacts with calcium hydroxide and hydrated calcium aluminate contained in the concrete in the reaction pool to produce ettringite crystals. The crystals themselves form a larger expansion, further expanding the crack and extending inward, and this cycle gradually deepens the crack. Therefore, the applicant considers that the forward positive pressure will be formed when the expansion of the crystals generated in the crack. Therefore, the depth of the crack can be determined by detecting the pressure. When the stress sensor embedded at a predetermined depth detects that the depth of the crack reaches the depth, an alarm signal is issued to alert that the pile should be repaired or replaced, thereby achieving building safety monitoring. Therefore, it has the advantages of convenience, reliability, etc.

[0010] Further, a detection member is provided beside the concrete pile to be monitored, the detection member is made of the same concrete material as the concrete pile, and the stress sensor is embedded in the detection member.

[0011] In this way, the concrete structure constituting the building pile refers to the structure of the detection member. The stress sensor is embedded therein and does not affect the structural strength of the pile due to the presence of the stress sensor itself.

[0012] Further, the detection member is a long strip arranged side by side with the concrete pile to be monitored and has the same width direction cross-sectional shape, and the two ends of the detection member in the height direction are pre-applied with simulated loads.

[0013] In this way, the detection member is pre-applied with simulated loads according to the size of the load borne by the concrete pile to be monitored, so that the two bear the same load size. Under the condition that the material structure and cross section of the two are the same, the crack and crack growth rate of the two can be kept consistent. The monitoring of the crack erosion depth of the detection member can better reflect the actual situation of the concrete pile to be monitored. Therefore, without affecting the strength of the concrete pile to be monitored, the erosion depth of the concrete pile to be monitored is monitored and the reliability of the monitoring is ensured.

[0014] Further, the stress sensor is implemented by using a strain gauge. In this way, the strain gauge is embedded in the detection member, and the expansion force of the ettringite crystal generated by the sulfate reaction at the front end of the crack of the concrete structure is converted into pressure on the strain gauge, and the sulfate corrosion depth is detected. The stress can be better monitored, and the installation is convenient.

[0015] Further, the method is implemented by using the following building pile safety monitoring system. The building pile safety monitoring system comprises a detection member arranged in parallel with the concrete pile to be monitored. The detection member is made of the same concrete material as the concrete pile. A strain gauge is embedded in the detection member at a monitoring depth position. The strain gauge is connected to the detection member through a connecting line embedded in the detection member and connected to a control device. The control device is connected to an alarm device.

[0016] In this way, the detection member simulates and reacts to the erosion condition of the concrete pile to be monitored. When the detection member is cracked and eroded to the monitoring depth, the forward expansion force formed by the ettringite crystal at the front end of the crack is detected by the strain gauge, and a signal is given to trigger the alarm device through the control device to alarm. Therefore, the internal erosion degree of the concrete pile to be monitored can be monitored and alarmed without affecting the strength of the concrete pile to be monitored. People can repair and maintain in time, and the safety of the building is improved. The alarm device can be an alarm, a flash lamp, or a signal transmitter. The signal transmitter can transmit an alarm signal to a mobile terminal for remote monitoring. However, the specific implementation is mature existing technology, which will not be described in detail.

[0017] Further, the detection member is a long strip arranged in parallel with the concrete pile to be monitored, and the width direction cross-sectional shape is consistent. Load loading devices are installed at the two ends of the detection member in the height direction. The load loading devices are used to load simulated loads on the detection member in the height direction.

[0018] In this way, the simulated load can be conveniently pre-applied to the detection member according to the load size of the concrete pile to be monitored, so that the two members bear the same load size. In the case that the material structure and cross section are the same, the crack and crack growth rate of the two members can be kept consistent. The monitoring of the crack erosion depth of the detection member can better reflect the actual situation of the concrete pile to be monitored. The accuracy and reliability of the monitoring are better ensured.

[0019] Further, the load loading device comprises two pressure plates pressed on the upper and lower ends of the detection member. The peripheral width of the pressure plate exceeds the width of the detection member, and a circle of perforations is uniformly arranged on the pressure plate. A pull rod is arranged in the perforations opposite to each other between the two pressure plates. The pull rod is a threaded section near the end position, and a tension nut is screwed on the part of the pull rod that penetrates out of the pressure plate.

[0020] In this way, by relying on the cooperation of the tension nut and the tie rod, an axial compressive load can be applied to the testing component in a convenient and quick manner, and the magnitude of the load force can be easily adjusted to be consistent with the actual load on the concrete pile to be monitored.

[0021] Furthermore, the tie rod is made of spring steel.

[0022] This allows the tie rod to generate tension more effectively to form a load and ensures a more durable load effect.

[0023] Furthermore, a pressure sensor for detecting the load magnitude is installed between the pressure plate and the testing component, and the pressure sensor is connected to the control device.

[0024] This allows for the detection of load changes and timely adjustments to ensure that the pressure on the testing component and the concrete pile under monitoring is consistent. The pressure on the concrete pile under monitoring can be obtained through evaluation calculations or by actually measuring the pressure by pre-installing pressure sensors at the root or top of the pile.

[0025] Furthermore, the testing components are fixed to the concrete pile to be monitored using clamps. This facilitates fixation.

[0026] Furthermore, the strain gauge is set parallel to the detection surface of the detection component.

[0027] This allows the expansion force generated by the sulfate reaction at the crack tip to be better converted into pressure directly facing the strain gauge and detected, thus improving the reliability of strain gauge detection.

[0028] Furthermore, multiple sets of strain gauges are embedded at different depths within the component to be tested.

[0029] This allows for alarms to be triggered at different levels of danger, thus improving building safety.

[0030] Furthermore, the strain gauge is mounted and fixed on the inner side of a rectangular frame structure made of rigid material.

[0031] This facilitates the installation and protection of strain gauges, and the support frame can easily bear the force when the strain gauges are subjected to stress, enabling the detection to be performed.

[0032] Furthermore, the support frame is coaxial and spaced apart with multiple strain gauges of different sizes, and each set of strain gauges is installed on the support frame of different sizes.

[0033] This makes it easier for each group of strain gauges to detect at different depths.

[0034] Furthermore, a strain gauge mounting groove is provided on the outer surface of the support frame. The depth of the strain gauge mounting groove is the same as the thickness of the strain gauge, and the strain gauge is installed in the mounting groove.

[0035] This facilitates better installation and protection of the strain gauges. During implementation, wiring channels are also provided on the outer surface of the support frame for arranging connecting wires.

[0036] Furthermore, a mesh skeleton is provided on the outer surface of the strain gauge, and the mesh size of the mesh skeleton is smaller than the size of the minimum aggregate of the detection component.

[0037] In this way, the mesh skeleton can protect the strain gauge during the production of the testing components, preventing it from being damaged by aggregates and concrete. More importantly, during monitoring, when the crack tip reaches the strain gauge, it first contacts and acts on the mesh skeleton. Because the mesh skeleton is a rigid material, it can effectively shield the lateral expansion force generated during crack formation, preventing this expansion force from affecting the strain gauge. This allows the strain gauge to only bear the forward positive pressure generated by the crystallization expansion at the crack tip, thus enabling better monitoring and detection. At the same time, because the crack tip is constrained by the mesh skeleton due to lateral expansion, the forward pressure of crystallization expansion is greater, thereby significantly improving the sensitivity of the strain gauge detection.

[0038] Furthermore, the mesh framework is made of steel wire mesh.

[0039] This gives it sufficient hardness to better achieve the aforementioned effects.

[0040] Furthermore, the mesh skeleton has a rectangular frame structure and is fitted over the supporting frame.

[0041] This makes installation and fixation easier and improves the protective effect.

[0042] Furthermore, an elastic material isolation membrane is also attached to the outer surface of the strain gauge.

[0043] In this way, the isolation membrane not only better protects the strain gauge from concrete erosion during specimen production, but more importantly, its presence ensures that the crack tip can only extend to the isolation membrane. The membrane's elasticity allows some of the expansion force acting on the strain gauge through the mesh skeleton to be transferred to the isolation membrane and neutralized by its elasticity as the crack expands. This further prevents the force of the crack extending laterally from affecting the strain gauge, ensuring that the strain gauge only bears the forward expansion force for better detection. Simultaneously, the membrane's elasticity allows it to open slightly when the crack tip reaches the strain gauge, allowing the crystallization expansion effect within the crack to act forward on the strain gauge, preventing the crack from completely failing to open and thus rendering the strain gauge unable to bear force. During implementation, the isolation membrane is positioned between the mesh skeleton and the strain gauge. As can be seen from the above principle, the simultaneous presence of the isolation membrane and the mesh skeleton not only better prevents the expansion force of the crack from acting on the strain gauge, but also complements each other, better protecting the strain gauge and improving its detection effect. During implementation, the isolation membrane is sealed and fixed to the support frame on all sides, while the isolation membrane and strain gauge can slide freely between them. To ensure that the above-mentioned effects of the separator can be better achieved.

[0044] In summary, this invention has the advantages of being simple and feasible to implement, having high monitoring reliability, strong practicality, and being able to better monitor the safety of building foundation piles under sulfate erosion in saline environments. Attached Figure Description

[0045] Figure 1 This is a structural schematic diagram of a building foundation pile safety monitoring system according to a specific embodiment of the present invention.

[0046] Figure 2 for Figure 1 A schematic diagram after the load loading device is removed.

[0047] Figure 3 for Figure 2 Cross-sectional view of a component used for separate testing.

[0048] Figure 4 for Figure 3 A magnified structural diagram of the individual strain gauge located at the center circle position.

[0049] Implementation

[0050] The present invention will now be described in further detail with reference to specific embodiments. Detailed Implementation

[0051] A method for safety monitoring of building foundation piles in saline environments is characterized by embedding stress sensors within the concrete structure constituting the building foundation piles. The stress sensors detect the expansion force of sulfate crystallization at the front end of cracks in the concrete structure to determine the depth of sulfate erosion, and trigger an alarm when the erosion depth reaches an alarm threshold.

[0052] This is because the process of sulfate erosion and damage to concrete structures is as follows: when cracks appear in the concrete structure, the narrowest point at the crack's tip naturally accumulates water vapor containing sulfate ions, forming a small reaction pool. The sulfate reacts with calcium hydroxide and hydrated calcium aluminate within this pool to produce ettringite crystals. These crystals expand significantly, further widening the crack and extending it inwards. This cycle continues, deepening the crack. Therefore, the applicant considers that the expansion of the crystals within the crack creates forward pressure. This pressure can be detected to determine the crack depth. By using stress sensors embedded at a predetermined depth, an alarm signal is triggered when the crack depth reaches that point, prompting the foundation pile to be repaired or replaced, thus achieving building safety monitoring. This method offers advantages such as convenience, speed, and reliability.

[0053] Among them, a detection component is set up next to the concrete pile to be monitored. The detection component is made of the same concrete material as the concrete pile, and the stress sensor is embedded in the detection component.

[0054] Thus, the concrete structure constituting the building's foundation piles refers to the structure of the testing component. The stress sensor is embedded within it, and its presence will not affect the structural strength of the foundation piles.

[0055] The testing component is a long strip with the same cross-sectional shape in the width direction as the concrete pile to be monitored, and simulated loads are pre-applied to both ends of the testing component in the height direction.

[0056] In this way, a simulated load is pre-applied to the testing component based on the load magnitude of the concrete pile to be monitored, ensuring that both components bear the same load. Given that their material structure and cross-section are identical, this ensures that the initiation of cracks and their crack growth rates remain consistent. This allows the monitoring of crack erosion depth in the testing component to better reflect the actual condition of the concrete pile to be monitored. Therefore, without affecting the strength of the concrete pile itself, the monitoring of its erosion depth is cleverly achieved, ensuring the reliability of the monitoring.

[0057] The stress sensor is implemented using strain gauges. By embedding strain gauges within the detection component, the expansion force caused by sulfate crystallization at the crack tip of the concrete structure is converted into pressure on the strain gauges, thus detecting the depth of sulfate erosion. This method is convenient to install and allows for better stress monitoring.

[0058] More specifically, this embodiment adopts Figures 1-4 The building foundation pile safety monitoring system shown includes a detection component 1 arranged parallel to the concrete foundation pile 6 to be monitored. The detection component 1 is made of the same concrete material as the concrete foundation pile. A strain gauge 2 is embedded in the detection component 1 at the monitoring depth. The strain gauge 2 is connected to the detection component 1 and the control device 4 through a connecting wire 3 embedded in the detection component. The control device 4 is connected to the alarm device 5.

[0059] In this way, by using a detection component to simulate and react to the erosion of the concrete foundation pile under monitoring, when the detection component develops cracks 24 and is eroded to the monitoring depth, strain gauges detect the forward expansion force formed by the expansion of ettringite crystals 25 at the front end of crack 24, and send a signal to trigger the alarm device via a control device. Therefore, it is possible to monitor and alarm on the degree of internal erosion of the concrete foundation pile without affecting its own strength, facilitating timely repair and maintenance and improving the safety of the building. The alarm device can be an alarm, a flashing light, or a signal transmitter, etc. The signal transmitter can be a mobile terminal to transmit alarm signals for convenient remote monitoring, but these are all mature existing technologies and will not be described in detail here.

[0060] Among them, the testing component 1 is a long strip with the same cross-sectional shape in the width direction as the concrete pile 6 to be monitored. Loading devices are installed at both ends of the testing component 1 in the height direction. The loading devices are used to apply simulated loads to the testing component in the height direction.

[0061] This allows for the convenient pre-application of simulated loads to the testing component based on the load magnitude of the concrete pile to be monitored. This ensures that both components bear the same load, and given identical material structure and cross-section, the occurrence and growth rates of cracks are consistent. This allows the monitoring of crack erosion depth in the testing component to better reflect the actual condition of the concrete pile under monitoring, thus better guaranteeing the accuracy and reliability of the monitoring.

[0062] The load loading device includes two pressure plates 7 pressed against the upper and lower ends of the testing component. The perimeter of the pressure plate 7 exceeds the width of the testing component and a ring of through holes is evenly distributed on it. A tie rod 8 is inserted through the through hole directly opposite the two pressure plates. The tie rod 8 has a threaded section near its end and a tension nut 9 is screwed onto the part that passes through the pressure plate.

[0063] In this way, by relying on the cooperation of the tension nut and the tie rod, an axial compressive load can be applied to the testing component in a convenient and quick manner, and the magnitude of the load force can be easily adjusted to be consistent with the actual load on the concrete pile to be monitored.

[0064] Among them, the tie rod 8 is made of spring steel.

[0065] This allows the tie rod to generate tension more effectively to form a load and ensures a more durable load effect.

[0066] Among them, a pressure detection sensor (not shown in the figure) for detecting the load size is also provided between the pressure plate 7 and the detection component 1. The pressure detection sensor is connected to the control device.

[0067] This allows for the detection of load changes and timely adjustments to ensure that the pressure on the testing component and the concrete pile under monitoring is consistent. The pressure on the concrete pile under monitoring can be obtained through evaluation calculations or by actually measuring the pressure by pre-installing pressure sensors at the root or top of the pile.

[0068] The testing component 1 is fixed to the concrete pile 6 to be monitored by a clamp 10. This facilitates the fixing process.

[0069] Among them, strain gauge 2 is set parallel to the detection surface of the detection component.

[0070] This allows the expansion force generated by the sulfate reaction at the crack tip to be better converted into pressure directly facing the strain gauge and detected, thus improving the reliability of strain gauge detection.

[0071] Among them, multiple strain gauges 2 are embedded in the component 1 to be tested at different depths.

[0072] This allows for tiered alarm systems based on different levels of danger, thus improving building safety.

[0073] The strain gauge 2 is mounted and fixed on the inner side of a rectangular frame structure made of rigid material, which is supported by a support frame 20.

[0074] This facilitates the installation and protection of strain gauges, and the support frame can easily bear the force when the strain gauges are subjected to stress, enabling the detection to be performed.

[0075] The support frame 20 is coaxial and has multiple strain gauges of different sizes spaced apart, and each set of strain gauges is installed on the support frame 20 of different sizes.

[0076] This makes it easier for each group of strain gauges to detect at different depths.

[0077] The outer surface of the support frame is provided with a strain gauge mounting groove 21. The depth of the strain gauge mounting groove 21 is the same as the thickness of the strain gauge, and the strain gauge is installed in the mounting groove.

[0078] This facilitates better installation and protection of the strain gauges. During implementation, wiring channels are also provided on the outer surface of the support frame for arranging connecting wires.

[0079] The strain gauge also has a mesh skeleton 22 on its outer surface. The mesh size of the mesh skeleton 22 is smaller than the size of the minimum aggregate of the detection component.

[0080] In this way, the mesh skeleton can protect the strain gauge during the production of the testing components, preventing it from being damaged by aggregates and concrete. More importantly, during monitoring, when the crack tip reaches the strain gauge, it first contacts and acts on the mesh skeleton. Because the mesh skeleton is a rigid material, it can effectively shield the lateral expansion force generated during crack formation, preventing this expansion force from affecting the strain gauge. This allows the strain gauge to only bear the forward positive pressure generated by the crystallization expansion at the crack tip, thus enabling better monitoring and detection. At the same time, because the crack tip is constrained by the mesh skeleton due to lateral expansion, the forward pressure of crystallization expansion is greater, thereby significantly improving the sensitivity of the strain gauge detection.

[0081] Among them, the mesh skeleton 22 is steel wire mesh.

[0082] This gives it sufficient hardness to better achieve the aforementioned effects.

[0083] The mesh skeleton 22 has a rectangular frame structure and is fitted outside the support frame 20.

[0084] This makes installation and fixation easier and improves the protective effect.

[0085] Among them, a layer of elastic material isolation membrane 23 is also attached to the outer surface of the strain gauge 2.

[0086] In this way, the isolation membrane not only better protects the strain gauge from concrete erosion during specimen production, but more importantly, its presence ensures that the crack tip can only extend to the isolation membrane. The elasticity of the isolation membrane allows some of the expansion force acting on the strain gauge through the mesh skeleton to act on the isolation membrane and be offset by its elasticity when the crack expands. This further better avoids the impact of the crack's lateral expansion force on the strain gauge, allowing it to only bear the forward expansion force for better detection. Simultaneously, the elasticity of the isolation membrane allows it to open a certain gap when the crack tip reaches the strain gauge, allowing the crystallization expansion effect within the crack to act forward on the strain gauge, preventing the crack from completely failing to open and thus rendering the strain gauge unable to bear force. During implementation, the isolation membrane is positioned between the mesh skeleton and the strain gauge. As can be seen from the above principle, the simultaneous presence of the isolation membrane and the mesh skeleton not only better prevents the crack's lateral expansion force from acting on the strain gauge, but also complements each other, better protecting the strain gauge and improving its detection effect. During implementation, the isolation membrane is sealed and fixed to the support frame on all sides, while the isolation membrane and strain gauge can slide freely between them. To ensure that the above-mentioned effects of the separator can be better achieved.

Claims

1. A building foundation pile safety monitoring system, characterized by, The detection member is made of the same concrete material as the concrete foundation pile, and a strain gauge is embedded in the detection member at a monitoring depth position. The detection member is a long strip-shaped member arranged in parallel with the concrete foundation pile to be monitored, and has the same width direction cross-sectional shape. The strain gauge is fixed to the support frame of the rectangular frame structure made of hard material. The support frames are coaxially and spacedly arranged in different sizes, and each group of strain gauges is installed on the support frames of different sizes. The support frame is provided with a strain gauge mounting groove on the outer surface. The strain gauge is mounted in the mounting groove. The strain gauge is further provided with a layer of mesh skeleton on the outer surface. The mesh skeleton is a steel mesh.

2. The building foundation pile safety monitoring system according to claim 1, wherein, The mesh skeleton is a rectangular frame structure and is sleeved outside the support frame.

3. The building pile safety monitoring system of claim 2, wherein, The load loading device includes two pressing plates pressed on the upper and lower ends of the detection member.

4. The building pile safety monitoring system of claim 2, wherein, The pressing plate is provided with a circle of perforations uniformly distributed on the periphery.

5. The building foundation pile safety monitoring system of claim 1, wherein, The pulling rod is made of spring steel material.

6. The building pile safety monitoring system of claim 1, wherein, The pressing plate and the detection member are further provided with a pressure detection sensor for detecting the load size. The detection member is fixed on the concrete foundation pile to be monitored by a hoop.

7. The building pile safety monitoring system of claim 1, wherein, The strain gauge is arranged parallel to the detection surface of the detection member. The detection member is embedded with multiple groups of strain gauges at different depth positions. The strain gauge is further provided with a layer of elastic material isolation film.

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