Foam concrete anti-knock performance regulation and control method

Abstract

The invention discloses a foam concrete anti-knock performance regulation and control method, and relates to the technical field of underground engineering protection.The method comprises the steps that anti-knock performance degradation sensitivity is obtained by obtaining rheological acoustic characteristic data in the foam concrete service process, calculating aging wave impedance and recognizing the pore compaction state; and a regulation and control instruction is generated in combination with a target threshold value, regulation and control are executed through initial design parameter optimization, a yielding support strategy and a rigidity compensation measure, and the regulation and control instruction is corrected based on new rheological acoustic characteristic data. Dynamic monitoring and accurate regulation and control of the anti-knock performance of the foam concrete are achieved, the problem of aging degradation of the anti-knock performance in the service process is effectively solved, and the anti-knock safety of underground engineering in the whole life period is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of underground engineering protection technology, and in particular to a method for controlling the blast resistance performance of foamed concrete. Background Technology

[0002] Critical infrastructure in energy, transportation, and national defense is a vital support for economic and social security and development, and also a key target for enemy attacks in modern warfare. Underground engineering, as a major form of construction for this type of infrastructure, faces serious threats from high-performance bunker-buster weapons. For example, the US military's B61-12 small earth-penetrating weapon can penetrate several meters into rock layers and explode, affecting depths of up to kilometers. Installing a foamed concrete buffer and shock-absorbing layer between the surrounding rock and the lining is an effective means to improve the blast resistance of underground engineering projects. Foamed concrete not only absorbs long-term deformation of the surrounding rock and improves the stress environment of the lining, but also dissipates the energy of the blast shock wave through pore deformation and fragmentation, reducing the damage to the structure caused by the explosion.

[0003] However, as the depth of underground engineering increases, the ground pressure and aging deformation generated by the overlying surrounding rock become increasingly significant. During the process of absorbing the long-term deformation of the surrounding rock to achieve pressure relief support, the foamed concrete layer will undergo compaction, leading to an increase in its wave impedance and a decrease in the degree of wave impedance mismatch with other media, thereby causing the blast resistance performance of the composite support structure to degrade over time.

[0004] Currently, existing research mainly focuses on the long-term deformation law of foamed concrete or the blast resistance of composite structures, lacking a systematic study on the dynamic relationship between the two. Furthermore, existing protective structure designs are based only on initial blast resistance performance and do not consider the time-related degradation during service, posing serious safety hazards.

[0005] The relevant technologies are difficult to accurately identify the pore compaction state of foamed concrete under long-term compression, and it is difficult to quantify the rate of blast resistance degradation. This leads to a lack of targeted control measures, which can easily result in unreasonable design parameters leading to insufficient blast resistance reserves. Furthermore, delayed control or inappropriate measures may fail to effectively curb performance degradation and thus fail to guarantee the blast resistance safety of underground engineering throughout its entire life cycle. Summary of the Invention

[0006] The technical problem solved by this invention is that existing technologies are difficult to accurately identify the pore compaction state of foamed concrete under long-term compression, and are difficult to quantify the rate of blast resistance degradation. This leads to a lack of targeted control measures, and is prone to unreasonable design parameters that result in insufficient blast resistance reserves. Furthermore, delayed control or inappropriate measures may fail to effectively curb performance degradation and thus fail to guarantee the blast resistance safety of underground engineering throughout its entire life cycle.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for controlling the blast resistance of foamed concrete, comprising the following steps:

[0008] Step S1: Based on the service process of foamed concrete, obtain rheological acoustic characteristic data, and use the rheological acoustic characteristic data to calculate the buffering capacity, obtain the time-effect wave impedance, and identify the pore compaction state.

[0009] Step S2: Based on the time-dependent wave impedance, obtain the resistance change amount, and obtain the explosion resistance performance degradation sensitivity by using the ratio of the compressive deformation amount and the resistance change amount.

[0010] Step S3: Set the target threshold and generate a control command based on the blast resistance performance degradation sensitivity and the target threshold;

[0011] Step S4: According to the control command, perform initial design parameter optimization and stiffness compensation to obtain new rheological acoustic characteristic data, obtain prediction results based on the new rheological acoustic characteristic data, and correct the control command based on the prediction results.

[0012] As a preferred embodiment of the method for controlling the blast resistance of foamed concrete according to the present invention, step S1 includes the following sub-steps:

[0013] Step S101, the rheological acoustic characteristic data includes the creep rate of the surrounding rock, the real-time density of the foamed concrete, the real-time wave velocity of the foamed concrete, and the acoustic emission signal generated during the compression process;

[0014] Step S102, the acoustic emission signal includes frequency characteristics and amplitude characteristics;

[0015] Step S103, the identification of pore compaction state is to obtain the frequency characteristics and amplitude characteristics based on the acoustic emission signal, and compare the frequency characteristics and amplitude characteristics with a preset pore feature library to obtain a matching value;

[0016] Step S104: The state with the highest matching value is taken as the current state, which includes the elastic compression stage and the pore collapse stage.

[0017] As a preferred embodiment of the method for controlling the blast resistance of foamed concrete according to the present invention, the calculation and characterization of buffer capacity includes the following sub-steps:

[0018] Step S105: Obtain the real-time density and real-time wave velocity of the foamed concrete using the rheological acoustic feature data.

[0019] Step S106: Calculate the product of the real-time density and the wave velocity as the time-effect wave impedance;

[0020] Step S107: Subtract the time-effect wave impedance from the preset target wave impedance threshold to obtain the deviation value, and compare the deviation value with the target wave impedance threshold to obtain the wave impedance mismatch.

[0021] The impedance mismatch is used to characterize the deviation between the current buffer capacity and the design capacity.

[0022] In a preferred embodiment of the method for controlling the blast resistance of foamed concrete according to the present invention, step S2 includes the following sub-steps:

[0023] Step S201: Based on the time-dependent wave impedance, obtain the impedance change, wherein the impedance change is characterized by the change in time-dependent wave impedance.

[0024] Step S202: Calculate the ratio of the resistance change to the pressure deformation as the sensitivity to explosion resistance performance degradation;

[0025] Step S203, the blast resistance degradation sensitivity is used to quantify the rate of blast resistance loss of foamed concrete under unit deformation.

[0026] As a preferred embodiment of the method for controlling the explosion-proof performance of foamed concrete according to the present invention, step S3 includes the following sub-steps:

[0027] Step S301: Generate control commands based on the impedance mismatch and the sensitivity to blast resistance degradation.

[0028] In step S302, the control command is that if the wave impedance mismatch is within a first preset safety range and the explosion-proof performance degradation sensitivity is within a second preset safety range, then the explosion-proof performance is determined to meet the requirements, and no control command is generated.

[0029] As a preferred embodiment of the method for controlling the explosion-proof performance of foamed concrete according to the present invention, step S3 further includes the following sub-steps:

[0030] Step S303: If the wave impedance mismatch exceeds the first preset safety range, then generate a first type of control command;

[0031] Step S304: If the blast resistance performance degradation sensitivity exceeds the second preset safety range, then generate a second type of control command.

[0032] In a preferred embodiment of the method for controlling the blast resistance of foamed concrete according to the present invention, step S4 includes the following sub-steps:

[0033] Step S401: According to the control instruction, when in the engineering design stage, the initial design parameters are optimized.

[0034] Step S402, the initial design parameter optimization aims to minimize the sensitivity to blast resistance degradation. It uses an intelligent algorithm to iteratively calculate different combinations of initial pouring parameters until the optimal combination of initial pouring parameters is determined. The initial pouring parameter combination refers to the mix design parameters and key process control parameters set before the preparation and pouring of foamed concrete.

[0035] As a preferred embodiment of the method for controlling the explosion-proof performance of foamed concrete according to the present invention, step S4 further includes the following sub-steps:

[0036] Step S403: According to the control command, when in the initial stage of service, the second type of control command executes the pressure relief support strategy.

[0037] Step S404, the pressure-relief support strategy is to utilize the low modulus characteristics of foamed concrete to allow the surrounding rock deformation to be released. When the surrounding rock deformation is released, rheological acoustic characteristic data is collected in real time to obtain new rheological acoustic characteristic data and monitor the pore compaction state.

[0038] Step S405: Based on the new rheological acoustic characteristic data, obtain the creep rate of the surrounding rock. When the creep rate of the surrounding rock is lower than the preset steady-state threshold and the pore compaction state is in the elastic compression stage, the pressure relief support strategy ends.

[0039] As a preferred embodiment of the method for controlling the blast resistance of foamed concrete according to the present invention, the implementation of stiffness compensation includes the following sub-steps:

[0040] Step S406: According to the control command, when the service life is in the later stage, the first type of control command performs stiffness compensation measures.

[0041] Step S407: When the pore compaction state is in the pore collapse stage and the blast resistance degradation sensitivity exceeds the second preset safety range, reinforcing grout is injected into the foamed concrete layer and a high modulus inner lining layer is added.

[0042] Step S408, the stiffness compensation measure is used to increase the overall modulus of the foamed concrete layer so that the time-dependent wave impedance returns to the target wave impedance threshold.

[0043] As a preferred embodiment of the method for controlling the blast resistance of foamed concrete according to the present invention, the prediction result correction and control instruction includes the following sub-steps:

[0044] Step S409: Feed the new rheological acoustic feature data back to the calculation process, and update the microstructure parameters according to the new rheological acoustic feature data. The calculation process is to calculate the time-dependent wave impedance, the blast resistance degradation sensitivity and the wave impedance mismatch. The microstructure parameters are the micro-geometric and physical properties of the internal pore structure and solid skeleton morphology of foamed concrete.

[0045] Step S410: Based on the updated microstructural parameters, re-predict the time-effect wave impedance and blast resistance degradation sensitivity for subsequent periods to obtain the prediction results;

[0046] Step S411: Adjust the control instructions based on the prediction results.

[0047] The beneficial effects of this invention are as follows: By collecting rheological and acoustic characteristic data such as the creep rate of surrounding rock, real-time density of foamed concrete, real-time wave velocity, and acoustic emission signals, it is possible not only to calculate the time-dependent quantification of buffering capacity based on wave impedance, but also to identify the pore compaction state (i.e., the elastic compression stage or the pore collapse stage) based on the frequency and amplitude characteristics of the acoustic emission signals. This solves the problem that traditional methods cannot comprehensively characterize the dynamic mechanical state of foamed concrete. Through two key indicators—wave impedance mismatch and blast resistance degradation sensitivity—quantitative assessment of buffering capacity deviation and performance degradation rate is achieved, providing accurate data support for subsequent control and avoiding control lag caused by ambiguous state judgment. To prevent misjudgments, differentiated control strategies were developed based on different stages of the project and the state of pore compaction. This formed a full-cycle control system encompassing source optimization, process control, and post-reinforcement. By collecting new rheological and acoustic characteristic data, the microstructural parameters of foamed concrete were updated, and the time-dependent wave impedance and blast resistance degradation sensitivity were re-predicted. Based on the prediction results, control commands were corrected, forming a closed-loop control mechanism of monitoring, calculation, control, feedback, and correction. This mechanism can track the control effect in real time, adjust control parameters and measures in a timely manner, avoid the blindness of control measures, and ensure that the control effect always matches the blast resistance performance requirements of the structure, significantly improving the accuracy and reliability of control. Attached Figure Description

[0048] Figure 1 The flowchart illustrates the steps of a method for controlling the blast resistance of foamed concrete according to an embodiment of the present invention. Detailed Implementation

[0049] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0050] Example, refer to Figure 1 A method for controlling the blast resistance of foamed concrete is provided, comprising the following steps:

[0051] Step S1: Based on the service process of foamed concrete, obtain rheological acoustic characteristic data, calculate and characterize the buffering capacity through the rheological acoustic characteristic data, obtain the time-effect wave impedance and identify the pore compaction state;

[0052] Step S2: Based on the time-dependent wave impedance, obtain the resistance change amount, and by using the ratio of the compressive deformation amount and the resistance change amount, obtain the explosion resistance performance degradation sensitivity.

[0053] Step S3: Set the target threshold and generate control instructions based on the blast resistance performance degradation sensitivity and the target threshold;

[0054] Step S4: According to the control command, perform initial design parameter optimization and implement stiffness compensation to obtain new rheological acoustic characteristic data. Based on the new rheological acoustic characteristic data, obtain the prediction results and correct the control command based on the prediction results.

[0055] Step S1: Based on the service process of foamed concrete, obtain rheological acoustic characteristic data, calculate and characterize the buffering capacity using the rheological acoustic characteristic data, obtain the time-dependent wave impedance, and identify the pore compaction state.

[0056] This step is the basic data collection and condition identification stage for blast resistance performance regulation. It comprehensively captures the dynamic service status of foamed concrete and surrounding rock through multi-dimensional data, providing accurate basis for subsequent performance evaluation and regulation.

[0057] Step S101, the rheological acoustic characteristic data includes the creep rate of the surrounding rock, the real-time density of the foamed concrete, the real-time wave velocity of the foamed concrete, and the acoustic emission signal generated during the compression process.

[0058] Rheological acoustic characteristic data is a core set of data reflecting the mechanical behavior and internal structural evolution of foamed concrete. Specifically, it includes the creep rate of the surrounding rock, the real-time density of the foamed concrete, the real-time wave velocity of the foamed concrete, and the acoustic emission signals generated during compression. Among them, the creep rate of the surrounding rock directly reflects the strength of the surrounding rock under long-term compression and is the core external factor causing the deformation of foamed concrete. The real-time density and wave velocity of the foamed concrete are key parameters for calculating wave impedance and are directly related to the buffering and damping capacity. The acoustic emission signal is the elastic wave generated by the release of energy when the pores inside the foamed concrete deform, collapse, or crack expand, which can intuitively reflect the changes in the internal structure.

[0059] Step S102: The acoustic emission signal includes frequency characteristics and amplitude characteristics.

[0060] Acoustic emission signals contain frequency and amplitude characteristics, which are key criteria for distinguishing the compaction state of pores. Frequency characteristics refer to the main frequency distribution range of the signal (in kHz), while amplitude characteristics refer to the signal intensity (in V). At different stages of pore compaction, the degree of drastic change in the internal structure of foamed concrete varies, and the amount of energy released also varies. Consequently, the frequency and amplitude of the corresponding acoustic emission signals will show significant differences. That is, in the elastic compression stage, the pore deformation is mild, the energy released is small, and the signal frequency is high with a small amplitude; in the pore collapse stage, the pores undergo severe deformation or breakage, the energy released is large, and the signal frequency is low with a large amplitude.

[0061] Step S103: Identify the pore compaction state by obtaining frequency and amplitude characteristics based on the acoustic emission signal, and comparing the frequency and amplitude characteristics with a preset pore feature library to obtain matching values.

[0062] The pore compaction state is identified by comparing the acoustic emission signal characteristics with a preset pore feature library. First, the collected acoustic emission signals are preprocessed by filtering and noise reduction to remove environmental noise interference such as construction vibration and equipment operation, and pure frequency and amplitude characteristics are extracted. Then, the extracted feature parameters are compared with standard data in the preset pore feature library to calculate the matching value. The matching value = feature overlap degree × 100%. The higher the feature overlap degree, the larger the matching value. Finally, the pore compaction state corresponding to the standard feature with the highest matching value is determined as the current state. The current state only includes the elastic compression stage and the pore collapse stage. The division between the two states directly determines the direction of subsequent control measures.

[0063] The construction of the pre-set pore feature library needs to be based on a large number of indoor compression tests. By selecting foamed concrete samples of different densities and strength grades, the signals of the entire process from elastic compression to pore collapse are collected by an acoustic emission monitoring system. Typical frequency ranges and amplitude intervals of each stage are extracted to establish a standardized feature database to ensure the accuracy of the identification results.

[0064] Step S104: The highest matching value is taken as the current state. The current state includes the elastic compression stage and the pore collapse stage.

[0065] Step S105: Obtain the real-time density and real-time wave velocity of foamed concrete using rheological acoustic characteristic data.

[0066] Step S106: Calculate the product of real-time density and wave velocity as the time-effect wave impedance;

[0067] Step S107: Subtract the time-effect wave impedance from the preset target wave impedance threshold to obtain the deviation value, and compare the deviation value with the target wave impedance threshold to obtain the wave impedance mismatch.

[0068] Impedance mismatch is used to characterize the deviation between the current buffer capacity and the design capacity.

[0069] Buffering capacity is quantitatively characterized by impedance mismatch. Time-dependent impedance is the core intermediate parameter for calculating impedance mismatch. The specific calculation process is as follows:

[0070] Real-time density was tested using a true density meter. Representative samples from different locations in the foamed concrete layer were selected, and after removing surface impurities, the test was repeated three times. The average value was taken to ensure accuracy. Real-time wave velocity was measured using an ultrasonic detector. The transmitting and receiving probes were placed close to the opposite surfaces of the foamed concrete to avoid air gaps affecting propagation. The wave velocity was calculated as wave velocity = probe spacing ÷ propagation time.

[0071] Wave impedance is the resistance of a medium to the propagation of stress waves. Its physical nature is determined by the density of the medium and the wave velocity. The calculation formula is: time-effect wave impedance = real-time density × real-time wave velocity (unit is kg / (m²・s)). Time-effect wave impedance directly reflects the current buffering and shock absorption capacity of foamed concrete.

[0072] First, the target wave impedance threshold is determined. This threshold is based on the engineering blast-resistant design requirements, foamed concrete design parameters, and surrounding rock characteristics. It is pre-set through numerical simulation and laboratory tests, and is typically within a reasonable range, such as 1.2 × 10⁻⁶. 6 -1.8×10 6 kg / (m²・s), then calculate the deviation value, that is, deviation value = time-dependent wave impedance - target wave impedance threshold midpoint, and finally obtain the result by wave impedance mismatch degree = (deviation value ÷ target wave impedance threshold midpoint) × 100%. The result directly quantifies the degree of deviation between the current buffer capacity and the design capacity.

[0073] This step, through the collection and analysis of multi-dimensional rheological acoustic characteristic data, achieves comprehensive monitoring of macroscopic mechanical parameters and microstructural state. Among them, the time-effect wave impedance quantifies the current buffering capacity, the pore compaction state reveals the evolution stage of the internal structure, and the wave impedance mismatch clarifies the deviation from the design requirements. The three together form the basis for the blast resistance performance evaluation. At the same time, it solves the problem that traditional methods only focus on a single parameter and cannot fully reflect the service state of foamed concrete. It provides data support for subsequent precise control and ensures the pertinence and rationality of control measures.

[0074] Step S2: Based on the time-dependent wave impedance, obtain the resistance change amount, and obtain the explosion resistance degradation sensitivity by using the ratio of the compressive deformation amount and the resistance change amount.

[0075] This step is the quantitative step of the blast resistance performance degradation rate, establishing the correlation between deformation and performance degradation, and providing a quantitative basis for determining whether regulation is needed and the intensity of regulation.

[0076] Step S201: Based on the time-dependent wave impedance, obtain the impedance change, which is characterized by the change in time-dependent wave impedance.

[0077] The change in resistance is characterized by the change in time-dependent wave impedance, reflecting the evolution trend of the buffering capacity of foamed concrete. Specifically, two consecutive service time points are selected, such as the first month and the third month, and the time-dependent wave impedance of these two points is calculated respectively. The change in resistance = the time-dependent wave impedance of the later time point - the time-dependent wave impedance of the earlier time point. If the change in resistance is positive, it indicates that the wave impedance has increased, the wave impedance matching degree between foamed concrete and surrounding rock and lining has decreased, and the buffering capacity has deteriorated. If it is negative, it indicates that the wave impedance has decreased, and the buffering capacity may have improved. This is usually caused by special working conditions, such as local stress release.

[0078] Step S202: Calculate the ratio of resistance change to pressure deformation as the sensitivity to blast resistance performance degradation.

[0079] The blast resistance degradation sensitivity is a core indicator for quantifying the rate of blast resistance loss under unit deformation. The calculation formula is: blast resistance degradation sensitivity = resistance change ÷ yield deformation (unit: kg / (m²・s・mm)). The yield deformation is the cumulative deformation of foamed concrete between two consecutive time points, which is obtained in real time by displacement sensor monitoring. That is, yield deformation = cumulative deformation of the later time point - cumulative deformation of the earlier time point.

[0080] For example, the aging impedance in the first month is 1.4 × 10⁻⁶. 6 kg / (m²・s), 1.52×10 in the third month. 6 kg / (m²・s), resistance change is 0.12×10 6 If the pressure is kg / (m²・s) and the deformation under pressure is 1.5 mm, then the blast resistance degradation sensitivity is 0.12 × 10⁻⁶. 6 ÷1.5 = 0.08 × 10 6 kg / (m²・s・mm), the blast resistance degradation sensitivity directly reflects the degree of loss of blast resistance of foamed concrete for every 1 mm of compressive deformation.

[0081] Step S203, the blast resistance degradation sensitivity is used to quantify the rate of blast resistance loss of foamed concrete under unit deformation.

[0082] The core function of the blast resistance degradation sensitivity is to quantify the stability of the blast resistance performance of foamed concrete. The larger the value, the more significant the change in wave impedance caused by unit deformation, the faster the blast resistance performance degrades, and the more likely it is to have insufficient blast resistance after long-term service. The smaller the value, the less the blast resistance performance is affected by deformation, and the stronger the stability.

[0083] This step transforms the qualitative description of the degradation of the anti-explosion performance of foamed concrete into a quantitative analysis by establishing a quantitative relationship between the change in resistance and the amount of compressive deformation. This solves the problem that traditional methods cannot accurately assess the degradation rate. Engineering technicians can quickly judge the dynamic evolution trend of the anti-explosion performance of foamed concrete through indicators. If the value exceeds the safe range, control measures can be initiated in a timely manner to avoid continuous performance degradation leading to anti-explosion failure. This provides a clear quantitative basis for control decisions and improves the scientificity and timeliness of control.

[0084] Step S3: Set the target threshold and generate control instructions based on the blast resistance performance degradation sensitivity and the target threshold.

[0085] This step is a decision-making process based on performance status assessment. It determines whether there is a risk to the explosion resistance performance by setting a preset safety threshold, and then generates targeted control instructions to ensure the necessity and accuracy of the control measures.

[0086] Step S301: Generate control commands based on impedance mismatch and blast resistance degradation sensitivity.

[0087] The target thresholds include the first preset safety range, namely the safe range of wave impedance mismatch, and the second preset safety range, namely the safe range of blast resistance performance degradation sensitivity. The target thresholds are set based on engineering blast resistance design standards, foamed concrete material characteristics, and a large amount of engineering practice data.

[0088] The first preset safety range is for the impedance mismatch. The impedance mismatch reflects the deviation between the buffering capacity and the design requirements. If the deviation is too large, the stress wave energy cannot be effectively dissipated. Based on engineering practice, when the absolute value of the impedance mismatch does not exceed 15%, the deviation between the buffering capacity and the design capacity is within an acceptable range. Therefore, the first preset safety range is set as [-15%, 15%].

[0089] The second preset safety range addresses the sensitivity to blast resistance degradation, reflecting the rate of performance degradation. If the rate is too fast, the blast resistance performance will exceed the design allowable range after long-term service. According to long-term service test data of foamed concrete, when the sensitivity to blast resistance degradation does not exceed 0.8 × 10⁻⁶, the blast resistance performance degradation is within acceptable limits. 6 At a concentration of kg / (m²・s・mm), performance degradation is under control; therefore, the second preset safety range is set to [0, 0.8 × 10⁻⁶]. 6 kg / (m²・s・mm)].

[0090] Step S302: If the wave impedance mismatch is within the first preset safety range and the explosion resistance performance degradation sensitivity is within the second preset safety range, then the explosion resistance performance is determined to meet the requirements, and no control command is generated.

[0091] If the impedance mismatch is within the first preset safety range and the blast resistance performance degradation sensitivity is within the second preset safety range, it indicates that the current buffering capacity of the foamed concrete deviates little from the design requirements, the performance degradation rate is controllable, and it can meet the blast resistance requirements of the project. At this time, no control command is generated, and only routine monitoring needs to be continued to ensure the performance status is stable.

[0092] For example, with a wave impedance mismatch of -4%, falling within the range of [-15%, 15%], the blast resistance degradation sensitivity is 0.08 × 10⁻⁶. 6 kg / (m²・s・mm), in [0, 0.8×10 6 If the value is [kg / (m²・s・mm)], then the explosion-proof performance is deemed to meet the requirements, and the routine monitoring schedule can be maintained.

[0093] In step S303, if the wave impedance mismatch exceeds the first preset safety range, a first type of control command is generated.

[0094] If the wave impedance mismatch exceeds the first preset safety range, i.e., the absolute value is >15%, it indicates that the current buffering capacity of the foamed concrete deviates too much from the design capacity and cannot effectively dissipate the explosive impact energy, which will lead to an increase in the impact load borne by the lining structure. At this time, the first type of control instruction is generated, the core objective of which is to adjust the wave impedance of the foamed concrete so that it returns to the target threshold range.

[0095] For example, if the impedance mismatch is 20%, which exceeds 15%, it indicates insufficient buffering capacity. Measures such as stiffness compensation are needed to improve the impedance matching, thus generating the first type of control command.

[0096] In step S304, if the sensitivity to blast resistance degradation exceeds the second preset safety range, a second type of control command is generated.

[0097] If the sensitivity to blast resistance degradation exceeds the second preset safety range, i.e., >0.8×10 6 If the value is kg / (m²・s・mm), it indicates that the rate of degradation of the blast resistance performance of foamed concrete is too fast, and it will quickly deviate from the design requirements after long-term service. At this time, a second type of control instruction is generated, the core objective of which is to reduce the rate of performance degradation and maintain the stability of blast resistance performance.

[0098] For example, the blast resistance degradation sensitivity is 1.0 × 10⁻⁶. 6 kg / (m²・s・mm), exceeding 0.8×10 6 If the value is kg / (m²・s・mm), then strategies such as pressure-bearing support are needed to reduce the excessive deformation of foamed concrete, thus generating a second type of control instruction.

[0099] This step establishes an automated decision-making logic of data calculation, threshold comparison, and instruction generation. By clearly defining target thresholds to classify safety and risk states, it avoids the subjectivity and errors of manual judgment. Corresponding control instructions are generated according to different performance risk types, making subsequent control measures clearly targeted. This avoids the waste of resources caused by blind control and prevents safety hazards caused by missed control, providing clear action guidelines for precise control.

[0100] Step S4: According to the control command, perform initial design parameter optimization and implement stiffness compensation to obtain new rheological acoustic characteristic data. Based on the new rheological acoustic characteristic data, obtain the prediction results and correct the control command based on the prediction results.

[0101] This step is the core execution and optimization link of the anti-blast performance control. The core is to implement targeted control measures according to the control instructions, combined with the different stages of the project and the state of the foamed concrete, and to continuously optimize through dynamic feedback to form a closed-loop control system of "execution-monitoring-correction".

[0102] Step S401: According to the control instructions, when in the engineering design stage, the initial design parameters are optimized.

[0103] The core objective of the engineering design phase is to reduce the risk of blast resistance degradation from the source. Therefore, when a second type of control command is generated or both types of commands are generated simultaneously, the initial design parameter optimization is performed. The initial design parameter optimization aims to minimize the sensitivity to blast resistance degradation. It uses intelligent algorithms to iteratively calculate different combinations of initial pouring parameters and finally determines the optimal parameter combination.

[0104] The initial casting parameter combination includes mix design parameters such as density, water-cement ratio, and foam content, as well as key process control parameters such as mixing time, casting speed, and curing conditions. These parameters directly determine the initial mechanical properties and degradation resistance of foamed concrete. The intelligent algorithm preferentially adopts the particle swarm optimization algorithm, which has the characteristics of fast convergence speed and strong global search capability. The specific implementation process is as follows:

[0105] Initialize the particle swarm by setting the particle swarm size, such as 50 particles, where each particle represents a set of initial casting parameters.

[0106] The iteration conditions are set as follows: number of iterations = 100, inertia weight = 0.7, and learning factor = c1 = c2 = 2.0.

[0107] The fitness is calculated using the sensitivity to blast resistance degradation as the fitness function, and the fitness value corresponding to each particle is calculated through numerical simulation.

[0108] Updating particle position and velocity involves continuously updating the particle's position and velocity based on its fitness value, in order to find the particle with the optimal fitness.

[0109] The optimal parameters are determined when the preset number of iterations is reached or the fitness converges. The optimal combination of parameters corresponding to the optimal particle is the optimal initial casting parameter combination.

[0110] For example, after iterative calculations, the optimal combination of initial pouring parameters is an initial density of 720 kg / m³, a water-cement ratio of 0.45, and a foam content of 40%. The optimal combination of initial pouring parameters corresponds to the least sensitivity to blast resistance degradation, which can ensure the stability of blast resistance performance from the source.

[0111] Step S402: The initial design parameter optimization aims to minimize the sensitivity to blast resistance degradation. It uses an intelligent algorithm to iteratively calculate different combinations of initial pouring parameters until the optimal combination of initial pouring parameters is determined. The initial pouring parameter combination consists of the mix design parameters and key process control parameters set before the preparation and pouring of foamed concrete.

[0112] The initial pouring parameter combination is a set of key parameters set before the preparation and pouring of foamed concrete. It directly affects the pore structure, density uniformity, and mechanical properties of foamed concrete. Among the mix design parameters, density determines the basic mechanical strength of foamed concrete, water-cement ratio affects the structural compactness after hardening, and foam content determines porosity and pore distribution. Among the key process control parameters, mixing time ensures uniform mixing of raw materials, pouring speed avoids uneven pore distribution, and curing conditions affect strength development and structural stability. The optimized combination of these parameters enables foamed concrete to form a reasonable pore structure and mechanical properties, laying the foundation for stable blast resistance during long-term service.

[0113] Step S403: According to the control instructions, when in the initial stage of service, the second type of control instructions will execute the pressure relief support strategy.

[0114] Step S404: The compression support strategy is to utilize the low modulus characteristics of foamed concrete to allow the surrounding rock deformation to be released. When the surrounding rock deformation is released, rheological acoustic characteristic data is collected in real time to obtain new rheological acoustic characteristic data and monitor the pore compaction state.

[0115] Step S405: Based on the new rheological acoustic characteristic data, obtain the creep rate of the surrounding rock. When the creep rate of the surrounding rock is lower than the preset steady-state threshold and the pore compaction state is in the elastic compression stage, the pressure relief support strategy is terminated.

[0116] In the initial service period, which is usually the first 5 years of the project's service, foamed concrete mainly bears the initial deformation and compression of the surrounding rock. If a second type of control command is generated at this time, a pressure relief support strategy needs to be implemented. By utilizing the low modulus of foamed concrete, i.e., the initial elastic modulus of 800-1200MPa, the surrounding rock is allowed to deform and release freely, thus preventing the foamed concrete from entering the pore collapse stage too early.

[0117] The specific execution process is as follows: First, without applying additional external constraints, the surrounding rock is allowed to deform freely under natural stress. The foamed concrete passively bears the compression and absorbs the stress of the surrounding rock through its own deformation. Then, during the compression process, rheological acoustic characteristic data are collected in real time according to the method in step S1, focusing on monitoring the creep rate and pore compaction state of the surrounding rock. Finally, the termination condition of the compression strategy is determined: when the creep rate of the surrounding rock is lower than the preset steady-state threshold, such as 0.01 mm / d, and the acoustic emission signal characteristics show that the pore compaction state is in the elastic compression stage, it indicates that the deformation of the surrounding rock has tended to stabilize and the foamed concrete has not been over-compacted. At this time, the compression support strategy is terminated and the conventional monitoring stage is entered.

[0118] For example, in the third year of service, the creep rate of the surrounding rock was monitored to be 0.03 mm / d, which is higher than 0.01 mm / d. The acoustic emission signal frequency was 320 kHz and the amplitude was 0.3 V, which is the characteristic of the elastic compression stage. The pressure relief support continued. In the fourth year, the creep rate of the surrounding rock dropped to 0.008 mm / d, which is lower than the steady-state threshold. The pore compaction state was still in the elastic compression stage. The pressure relief support was terminated.

[0119] Step S406: According to the control instructions, when the service is in the late stage, the first type of control instructions will implement stiffness compensation measures.

[0120] Step S407: When the pore compaction state is in the pore collapse stage and the blast resistance degradation sensitivity exceeds the second preset safety range, reinforcing grout is injected into the foamed concrete layer and a high modulus inner lining layer is added.

[0121] Step S408: Stiffness compensation measures are used to increase the overall modulus of the foamed concrete layer, so that the time-dependent wave impedance returns to the target wave impedance threshold.

[0122] In the later stages of service, typically after more than 30 years of service, foamed concrete is prone to pore collapse due to long-term compression. If a first-class control command is generated or two types of commands are generated simultaneously, stiffness compensation measures need to be implemented to improve the overall modulus of the foamed concrete layer through external intervention, so that the time-dependent wave impedance returns to the target threshold.

[0123] The implementation conditions for stiffness compensation measures are that the acoustic emission signal characteristics show that the pore compaction state is in the pore collapse stage, and the sensitivity of blast resistance degradation exceeds the second preset safety range. At this time, a large number of pores inside the foamed concrete collapse, the buffering capacity decreases significantly, and external reinforcement is needed to restore the performance.

[0124] The specific implementation process involves injecting reinforcing grout, specifically epoxy resin-based reinforcing grout. Epoxy resin-based reinforcing grout has the characteristics of high bonding strength and good permeability, which can fill the collapsed pores inside foamed concrete. A segmented injection method is adopted, with each segment being 5m long. The injection pressure is controlled at 0.8-1.2MPa, and the injection volume is 0.5-0.8m³ / m, ensuring that the grout fills the pores evenly.

[0125] Adding a high-modulus inner lining layer involves adding a carbon fiber reinforced polymer (CFRP) inner lining layer between the foamed concrete and the lining. The elastic modulus of CFRP is 150-200 GPa, which can significantly improve the overall stiffness of the foamed concrete layer. The thickness of the inner lining layer is set to 10-15 mm. It is constructed by adhesive bonding. Before construction, the surface of the foamed concrete is ground, cleaned, and an interface agent is applied to ensure a firm bond.

[0126] The effect verification involves testing the real-time density and wave velocity of the foamed concrete according to the method in step S1 after 7-14 days of curing, calculating the time-dependent wave impedance, and determining whether it has returned to the target wave impedance threshold. If the target has not been reached, the injection volume or the thickness of the inner lining layer needs to be adjusted, and compensation needs to be implemented again.

[0127] Step S409: Feed the new rheological acoustic feature data back to the calculation process, update the microstructure parameters based on the new rheological acoustic feature data, and calculate the time-dependent wave impedance, the blast resistance degradation sensitivity and the wave impedance mismatch. The microstructure parameters are the micro-geometric and physical properties of the internal pore structure and solid skeleton morphology of the foamed concrete.

[0128] Step S410: Based on the updated microstructural parameters, re-predict the time-effect wave impedance and blast resistance degradation sensitivity for subsequent periods to obtain the prediction results;

[0129] Step S411: Adjust the control instructions based on the prediction results.

[0130] Dynamic feedback correction is the core mechanism to ensure the continuous optimization of the control effect. The specific implementation process is to obtain new rheological acoustic characteristic data. That is, after the control measures are implemented, the creep rate of the surrounding rock, the real-time density of foamed concrete, the real-time wave velocity and acoustic emission signal are re-acquired according to the method in step S1 to obtain new rheological acoustic characteristic data. The new rheological acoustic characteristic data reflects the performance status after control.

[0131] Updating microstructural parameters refers to updating the microscopic properties of the internal pore structure and solid skeleton morphology of foamed concrete, including porosity, pore size distribution, pore morphology, and solid skeleton density. These parameters directly affect density, wave velocity, and wave impedance. Based on new rheological acoustic characteristic data, microstructural parameters are updated through CT scans or electron microscopy analysis. For example, if the porosity was 45% before adjustment, it may be reduced to 32% after adjustment.

[0132] The microstructural parameters of the upcoming performance update are input into numerical calculation software, such as LS-DYNA. An elastoplastic constitutive model is used to simulate the mechanical behavior of foamed concrete, and the aging wave impedance and blast resistance degradation sensitivity in subsequent periods, such as 1-5 years, are re-predicted to obtain the prediction results.

[0133] If the prediction results show that the time-effect impedance will exceed the target threshold or the degradation sensitivity will exceed the safe range in the subsequent period, it indicates that the effect of the current control measures cannot be sustained and the control instructions need to be corrected, such as implementing stiffness compensation again in advance or adjusting the compensation parameters; if the prediction results show that the performance is stable within the safe range, the original control strategy is maintained and routine monitoring continues.

[0134] This step constructs a complete closed-loop system of phased control and dynamic feedback. Based on the different characteristics of the engineering design stage, the initial service stage, and the later service stage, targeted measures such as initial parameter optimization, pressure relief support, and stiffness compensation are implemented. This solves the problems of poor targeting and limited effectiveness of traditional control measures. Parameter optimization in the design stage reduces the risk of degradation from the source. The pressure relief strategy in the initial service stage coordinates the deformation of the surrounding rock and the support structure. Stiffness compensation in the later service stage restores the buffer capacity. The dynamic feedback correction mechanism ensures that the control measures are always matched with the performance state, avoiding insufficient or excessive control. The entire process achieves precise control of the blast resistance performance of foamed concrete throughout its entire life cycle, effectively curbing time-related degradation, ensuring the blast resistance safety of underground engineering throughout its entire life cycle, while reducing control costs and improving the economic efficiency of the project.

[0135] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0136] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling the blast resistance of foamed concrete, characterized in that, Includes the following steps: Step S1: Based on the service process of foamed concrete, obtain rheological acoustic characteristic data, calculate the buffering capacity through the rheological acoustic characteristic data, obtain the time-effect wave impedance and identify the pore compaction state; Step S2: Based on the time-dependent wave impedance, obtain the resistance change amount, and obtain the explosion resistance performance degradation sensitivity by using the ratio of the compressive deformation amount and the resistance change amount. Step S3: Set the target threshold and generate a control command based on the blast resistance performance degradation sensitivity and the target threshold; Step S4: According to the control command, perform initial design parameter optimization and implement stiffness compensation to obtain new rheological acoustic characteristic data, obtain prediction results based on the new rheological acoustic characteristic data, and correct the control command based on the prediction results.

2. The method for controlling the blast resistance of foamed concrete as described in claim 1, characterized in that, Step S1 includes the following sub-steps: Step S101, the rheological acoustic characteristic data includes the creep rate of the surrounding rock, the real-time density of the foamed concrete, the real-time wave velocity of the foamed concrete, and the acoustic emission signal generated during the compression process; Step S102, the acoustic emission signal includes frequency characteristics and amplitude characteristics; Step S103, the identification of pore compaction state is to obtain the frequency characteristics and amplitude characteristics based on the acoustic emission signal, and compare the frequency characteristics and amplitude characteristics with a preset pore feature library to obtain a matching value; Step S104: The state with the highest matching value is taken as the current state, which includes the elastic compression stage and the pore collapse stage.

3. The method for controlling the blast resistance of foamed concrete as described in claim 2, characterized in that, The calculation of buffer capacity includes the following sub-steps: Step S105: Obtain the real-time density and real-time wave velocity of the foamed concrete using the rheological acoustic feature data. Step S106: Calculate the product of the real-time density and the wave velocity as the time-effect wave impedance; Step S107: Subtract the time-effect wave impedance from the preset target wave impedance threshold to obtain the deviation value, and compare the deviation value with the target wave impedance threshold to obtain the wave impedance mismatch. The impedance mismatch is used to characterize the deviation between the current buffer capacity and the design capacity.

4. The method for controlling the blast resistance of foamed concrete as described in claim 3, characterized in that, Step S2 includes the following sub-steps: Step S201: Based on the time-dependent wave impedance, obtain the impedance change, wherein the impedance change is characterized by the change in time-dependent wave impedance. Step S202: Calculate the ratio of the resistance change to the pressure deformation as the sensitivity to explosion resistance performance degradation; Step S203, the blast resistance degradation sensitivity is used to quantify the rate of blast resistance loss of foamed concrete under unit deformation.

5. The method for controlling the blast resistance of foamed concrete as described in claim 4, characterized in that, Step S3 includes the following sub-steps: Step S301: Generate control commands based on the impedance mismatch and the sensitivity to blast resistance degradation. In step S302, the control command is that if the wave impedance mismatch is within a first preset safety range and the explosion-proof performance degradation sensitivity is within a second preset safety range, then the explosion-proof performance is determined to meet the requirements, and no control command is generated.

6. The method for controlling the blast resistance of foamed concrete as described in claim 5, characterized in that, Step S3 further includes the following sub-steps: Step S303: If the wave impedance mismatch exceeds the first preset safety range, then generate a first type of control command; Step S304: If the blast resistance performance degradation sensitivity exceeds the second preset safety range, then generate a second type of control command.

7. The method for controlling the blast resistance of foamed concrete as described in claim 6, characterized in that, Step S4 includes the following sub-steps: Step S401: According to the control instruction, when in the engineering design stage, the initial design parameters are optimized. Step S402, the initial design parameter optimization aims to minimize the sensitivity to blast resistance degradation. It uses an intelligent algorithm to iteratively calculate different combinations of initial pouring parameters until the optimal combination of initial pouring parameters is determined. The initial pouring parameter combination refers to the mix design parameters and key process control parameters set before the preparation and pouring of foamed concrete.

8. The method for controlling the blast resistance of foamed concrete as described in claim 7, characterized in that, Step S4 further includes the following sub-steps: Step S403: According to the control command, when in the initial stage of service, the second type of control command executes the pressure relief support strategy. Step S404, the pressure-relief support strategy is to utilize the low modulus characteristics of foamed concrete to allow the surrounding rock deformation to be released. When the surrounding rock deformation is released, rheological acoustic characteristic data is collected in real time to obtain new rheological acoustic characteristic data and monitor the pore compaction state. Step S405: Based on the new rheological acoustic characteristic data, obtain the creep rate of the surrounding rock. When the creep rate of the surrounding rock is lower than the preset steady-state threshold and the pore compaction state is in the elastic compression stage, the pressure relief support strategy ends.

9. The method for controlling the blast resistance of foamed concrete as described in claim 8, characterized in that, The implementation of stiffness compensation includes the following sub-steps: Step S406: According to the control command, when the service life is in the later stage, the first type of control command performs stiffness compensation measures. Step S407: When the pore compaction state is in the pore collapse stage and the blast resistance degradation sensitivity exceeds the second preset safety range, reinforcing grout is injected into the foamed concrete layer and a high modulus inner lining layer is added. Step S408, the stiffness compensation measures are used to increase the overall modulus of the foamed concrete layer so that the time-dependent wave impedance returns to the target wave impedance threshold.

10. The method for controlling the blast resistance of foamed concrete as described in claim 9, characterized in that, The prediction result correction and control instruction includes the following sub-steps: Step S409: Feed the new rheological acoustic feature data back to the calculation process, and update the microstructure parameters according to the new rheological acoustic feature data. The calculation process is to calculate the time-dependent wave impedance, the blast resistance degradation sensitivity and the wave impedance mismatch. The microstructure parameters are the micro-geometric and physical properties of the internal pore structure and solid skeleton morphology of foamed concrete. Step S410: Based on the updated microstructural parameters, re-predict the time-effect wave impedance and blast resistance degradation sensitivity for subsequent periods to obtain the prediction results; Step S411: Adjust the control instructions based on the prediction results.

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