Safety control method, system and device for bridge pile foundation structure under blasting vibration influence and medium

Abstract

The invention discloses a safety control method, system and device for a bridge pile foundation structure under the influence of blasting vibration and a medium. The method comprises the steps that on-site blasting parameters, structure parameters of the bridge pile foundation structure, vibration velocity data under blasting and stratum parameters of a stratum where the bridge pile foundation structure is located are obtained; a finite element overall model of the bridge pile foundation structure is established according to the field blasting parameters, the structure parameters and the stratum parameters; obtaining the maximum tensile stress and the maximum vibration speed of the bridge pile foundation structure under different horizontal explosion center distances on the basis of the finite element overall model, and carrying out related fitting to obtain a safety control standard relational expression of the maximum tensile stress and the maximum vibration speed; determining the maximum safety allowable vibration velocity according to the maximum tensile stress design value and the safety control standard relational expression; and if the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm is given to prompt to adjust on-site blasting parameters or take protective measures. According to the method, the influence of blasting vibration on the bridge pile foundation structure can be accurately evaluated, and the safety of a bridge is ensured.

Description

Technical Field

[0001] The present application relates to the technical field related to bridge dynamic response, and in particular to a method, system, device and medium for safely controlling a bridge pile foundation structure under the influence of blasting vibration. Background Art

[0002] Blasting is a common method used during canal excavation to break up rock and earth to improve construction efficiency. However, blasting generates strong vibrations that propagate through the surrounding medium in the form of waves. When these vibrations reach nearby bridge pile foundations, they exert dynamic effects on them. Bridge pile foundations are a crucial component of bridge structures, responsible for transferring the loads of the bridge superstructure to the subsoil. The stability and safety of the pile foundations are directly related to the reliability of the entire bridge structure. Therefore, studying the dynamic response characteristics of bridge pile foundations to blasting vibrations is crucial for ensuring bridge safety.

[0003] Since monitoring the dynamic stress of pile foundations under realistic conditions is difficult, the traditional method of judging the structural failure of bridge pile foundation structures under the influence of blasting vibration by using the maximum tensile stress criterion is difficult to implement. This leads to inaccurate assessment results of the impact of blasting vibration on bridge pile foundation structures, making it difficult to ensure the safety of bridges. Summary of the Invention

[0004] This application aims to solve at least one of the technical problems existing in the prior art. To this end, this application proposes a safety control method for bridge pile foundation structures under the influence of blasting vibration, which can accurately assess the impact of blasting vibration on bridge pile foundation structures and ensure the safety of bridges.

[0005] The present application also provides a safety control system for a bridge pile foundation structure under the influence of blasting vibration, a control device for executing the above-mentioned safety control method for a bridge pile foundation structure under the influence of blasting vibration, and a computer-readable storage medium.

[0006] According to a first aspect of the present application, a safety control method for a bridge pile foundation structure under the influence of blasting vibration comprises: Acquiring on-site blasting parameters, structural parameters of the bridge pile foundation structure, vibration velocity data under blasting, and stratum parameters of the stratum where the bridge pile foundation structure is located; Establishing a finite element integral model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters and the stratum parameters; Based on the finite element overall model, the stress condition of the bridge pile foundation structure under blasting vibration is simulated to obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure under different horizontal blast center distances; Correlation fitting is performed based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances to obtain a safety control standard relationship between the maximum tensile stress and the maximum vibration velocity; Determine the maximum safe allowable vibration speed based on the preset maximum tensile stress design value and the safety control standard relationship; If the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm is issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures.

[0007] The safety control method for a bridge pile foundation structure under the influence of blasting vibration according to the embodiment of the present application has at least the following beneficial effects: Because monitoring dynamic stress in pile foundations under realistic conditions is difficult, the traditional method of using the maximum tensile stress criterion to determine structural failure of bridge pile foundations under the influence of blasting vibration is difficult to implement, resulting in inaccurate assessment results of the impact of blasting vibration on bridge pile foundation structures and difficulty in ensuring bridge safety. This application establishes a finite element integral model corresponding to the bridge pile foundation structure. Based on the finite element integral model, the stress conditions of the bridge pile foundation structure under blasting vibration are simulated to obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances. This solves the problem of the limited number and scattered locations of actual monitoring devices, making it difficult to obtain accurate maximum tensile stress and maximum vibration velocity. Then, by performing correlation fitting based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances, the safety control standard relationship between the maximum tensile stress and the maximum vibration velocity is obtained. Finally, the maximum safe allowable vibration velocity is determined based on the preset maximum tensile stress design value and the safety control standard relationship. When the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm is issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures. According to the maximum tensile stress criterion, the tensile stress is converted into the vibration velocity as a quantitative indicator to control the safety of the bridge pile foundation structure. This solves the problem that pile foundation dynamic stress monitoring under realistic conditions is difficult and the traditional method of judging the structural failure of the bridge pile foundation structure under the influence of blasting vibration by the maximum tensile stress criterion is difficult to carry out. It can accurately evaluate the impact of blasting vibration on the bridge pile foundation structure and ensure the safety of the bridge.

[0008] According to some embodiments of the present application, the structural parameters include concrete structure and steel structure, and the stratum parameters include rock mass structure; The step of establishing a finite element integral model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters, and the stratum parameters includes: The steel structure is divided using rod elements, and the concrete structure and the rock structure are divided using hexahedron elements to obtain an initial finite element model; Based on the initial finite element model, a dynamic explicit elastic-plastic model is used to describe the mechanical properties of the concrete structure and the steel structure, and an elastic-plastic rock and soil constitutive model is used to describe the mechanical properties of the rock structure, thereby obtaining an intermediate finite element model; An actual blasting load is determined according to the on-site blasting parameters, and the actual blasting load is loaded on the intermediate finite element model to obtain the overall finite element model.

[0009] According to some embodiments of the present application, determining the actual blasting load according to the on-site blasting parameters includes: establishing a single blasthole model according to the on-site blasting parameters; Applying an elastic boundary to the inner wall of the blasthole model; The other blast holes are applied to the elastic boundary of the single blast hole model in the form of equivalent loads to obtain the actual blasting load.

[0010] According to some embodiments of the present application, simulating the stress condition of the bridge pile foundation structure under blasting vibration based on the finite element overall model to obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances includes: Based on the finite element overall model, the stress condition of the bridge pile foundation structure under blasting vibration is simulated to obtain the tensile stress distribution data and vibration velocity distribution data of the bridge pile foundation structure under different horizontal blast center distances; determining the maximum tensile stress of the bridge pile foundation structure at different horizontal explosion center distances according to the tensile stress distribution data of the bridge pile foundation structure at different horizontal explosion center distances; The maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances is determined according to the vibration velocity distribution data of the bridge pile foundation structure at different horizontal explosion center distances.

[0011] According to some embodiments of the present application, the method further includes: Based on the finite element overall model, the stress condition of the bridge pile foundation structure under the blasting vibration is simulated to obtain the tensile stress distribution of the bridge pile foundation structure under the influence of the blasting vibration; Determining a target position corresponding to a maximum tensile stress on the bridge pile foundation structure according to the tensile stress distribution; The target position is determined as a vulnerable part of the bridge pile foundation structure to achieve reinforcement and protection of the vulnerable part.

[0012] According to some embodiments of the present application, after establishing the finite element integral model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters, and the stratum parameters, the method further includes: Obtaining measured tensile stress data and measured vibration velocity data of the bridge pile foundation structure; Based on the finite element overall model, simulating the stress condition of the bridge pile foundation structure under the influence of blasting vibration, and obtaining simulated tensile stress data and simulated vibration velocity data of the bridge pile foundation structure under the influence of blasting vibration; Comparing and verifying the simulated tensile stress data and the simulated vibration velocity data with the measured tensile stress data and the measured vibration velocity data to evaluate the validity of the finite element overall model; When the effectiveness reaches the preset standard, the finite element overall model is executed to simulate the stress condition of the bridge pile foundation structure under blasting vibration, and the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure under different horizontal explosion center distances are obtained.

[0013] According to some embodiments of the present application, the method further includes: Based on the finite element overall model, the stress condition of the bridge pile foundation structure under the blasting vibration is simulated to obtain the tensile stress distribution and vibration velocity distribution of the bridge pile foundation structure under the influence of the blasting vibration; determining the dynamic stress distribution characteristics of the bridge pile foundation structure according to the tensile stress distribution; determining a blasting vibration velocity distribution characteristic of the bridge pile foundation structure according to the vibration velocity distribution; The dynamic response characteristics of the bridge pile foundation structure are analyzed based on the dynamic stress distribution characteristics and the blasting vibration velocity distribution characteristics, so as to achieve structural optimization of the bridge pile foundation structure according to the dynamic response characteristics.

[0014] According to a second aspect of the present application, a safety control system for a bridge pile foundation structure under the influence of blasting vibration comprises: a data acquisition unit, configured to acquire on-site blasting parameters, structural parameters of the bridge pile foundation structure, vibration velocity data under blasting, and stratum parameters of the stratum where the bridge pile foundation structure is located; a finite element overall model building unit, configured to build a finite element overall model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters, and the stratum parameters; A finite element simulation unit is used to simulate the stress condition of the bridge pile foundation structure under blasting vibration based on the finite element overall model, and obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure under different horizontal blast center distances; a safety control standard relationship determination unit, configured to perform correlation fitting based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances to obtain a safety control standard relationship between the maximum tensile stress and the maximum vibration velocity; a maximum safe allowable vibration speed determining unit, configured to determine the maximum safe allowable vibration speed based on a preset maximum tensile stress design value and the safety control standard relationship; The alarm unit is used to issue an alarm when the vibration velocity data exceeds the maximum safe allowable vibration velocity, prompting the construction party to adjust the on-site blasting parameters or take protective measures.

[0015] The safety control system for a bridge pile foundation structure under the influence of blasting vibration according to the embodiment of the present application has at least the following beneficial effects: Because monitoring dynamic stress in pile foundations under realistic conditions is difficult, the traditional method of using the maximum tensile stress criterion to determine structural failure of bridge pile foundations under the influence of blasting vibration is difficult to implement, resulting in inaccurate assessment results of the impact of blasting vibration on bridge pile foundation structures and difficulty in ensuring bridge safety. This application establishes a finite element integral model corresponding to the bridge pile foundation structure. Based on the finite element integral model, the stress conditions of the bridge pile foundation structure under blasting vibration are simulated to obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances. This solves the problem of the limited number and scattered locations of actual monitoring devices, making it difficult to obtain accurate maximum tensile stress and maximum vibration velocity. Then, by performing correlation fitting based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances, the safety control standard relationship between the maximum tensile stress and the maximum vibration velocity is obtained. Finally, the maximum safe allowable vibration velocity is determined based on the preset maximum tensile stress design value and the safety control standard relationship. When the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm is issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures. According to the maximum tensile stress criterion, the tensile stress is converted into the vibration velocity as a quantitative indicator to control the safety of the bridge pile foundation structure. This solves the problem that pile foundation dynamic stress monitoring under realistic conditions is difficult and the traditional method of judging the structural failure of the bridge pile foundation structure under the influence of blasting vibration by the maximum tensile stress criterion is difficult to carry out. It can accurately evaluate the impact of blasting vibration on the bridge pile foundation structure and ensure the safety of the bridge.

[0016] According to a third embodiment of the present application, a control device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for safely controlling a bridge pile foundation structure under the influence of blasting vibration as described in the first embodiment. Because the control device utilizes all of the technical solutions of the method for safely controlling a bridge pile foundation structure under the influence of blasting vibration described in the above embodiment, it at least has all of the beneficial effects provided by the technical solutions of the above embodiment.

[0017] According to a fourth embodiment of the present application, a computer-readable storage medium stores computer-executable instructions for executing the method for safely controlling a bridge pile foundation structure under the influence of blasting vibration as described in the first embodiment. Because the computer-readable storage medium incorporates all of the technical solutions of the method for safely controlling a bridge pile foundation structure under the influence of blasting vibration described in the aforementioned embodiment, it at least exhibits all of the beneficial effects provided by the technical solutions of the aforementioned embodiments.

[0018] Other features and advantages of the present application will be set forth in the following description, and in part will be apparent from the description, or may be learned by practicing the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 This is a flow chart of a safety control method for a bridge pile foundation structure under the influence of blasting vibration according to an embodiment of the present application; Figure 2 is a schematic diagram of on-site blasting construction according to an embodiment of the present application; Figure 3 This is a schematic diagram of layered blasting excavation according to an embodiment of the present application; Figure 4 is a schematic diagram of the arrangement of on-site monitoring points according to an embodiment of the present application; Figure 5 is a schematic diagram of a finite element overall model of an embodiment of the present application; Figure 6 This is a schematic diagram of equidistantly arranged nine different blasting source positions and layered blasting according to an embodiment of the present application; Figure 7 Schematic diagram of the validity verification of the finite element overall model of an embodiment of the present application; Figure 8 This is a schematic diagram of the maximum tensile stress distribution of a bridge pile foundation structure according to an embodiment of the present application; Figure 9 is a schematic diagram of vibration stress waves of different layered blastings according to an embodiment of the present application; Figure 10 This is a schematic diagram of the maximum vibration velocity distribution of a bridge pile foundation structure according to an embodiment of the present application; Figure 11 is a schematic diagram of a vulnerable portion of a bridge pile foundation structure according to an embodiment of the present application; Figure 12 Schematic diagram of a safety control standard relationship formula according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0021] In the description of this application, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0022] In the description of this application, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0023] In the description of this application, it should be noted that, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technical personnel in the relevant technical field can reasonably determine the specific meaning of the above terms in this application based on the specific content of the technical solution.

[0024] The following will be combined Figures 1 to 12 A clear and complete description is given of the safety control method of the bridge pile foundation structure under the influence of blasting vibration in the embodiment of the present application. Obviously, the embodiment described below is only a part of the embodiments of the present application, not all of the embodiments.

[0025] refer to Figures 1 to 12 , Figure 1 This is a flow chart of a safety control method for a bridge pile foundation structure under the influence of blasting vibration according to an embodiment of the present application; Figure 2 is a schematic diagram of on-site blasting construction according to an embodiment of the present application; Figure 3 This is a schematic diagram of layered blasting excavation according to an embodiment of the present application; Figure 4 is a schematic diagram of the arrangement of on-site monitoring points according to an embodiment of the present application; Figure 5 is a schematic diagram of a finite element overall model of an embodiment of the present application; Figure 6 This is a schematic diagram of equidistantly arranged nine different blasting source positions and layered blasting according to an embodiment of the present application; Figure 7 Schematic diagram of the validity verification of the finite element overall model of an embodiment of the present application; Figure 8 This is a schematic diagram of the maximum tensile stress distribution of a bridge pile foundation structure according to an embodiment of the present application; Figure 9 is a schematic diagram of vibration stress waves of different layered blastings according to an embodiment of the present application; Figure 10This is a schematic diagram of the maximum vibration velocity distribution of a bridge pile foundation structure according to an embodiment of the present application; Figure 11 is a schematic diagram of a vulnerable portion of a bridge pile foundation structure according to an embodiment of the present application; Figure 12 Schematic diagram of a safety control standard relationship formula according to an embodiment of the present application.

[0026] According to the first aspect of the present application, a safety control method for a bridge pile foundation structure under the influence of blasting vibration comprises: Obtain on-site blasting parameters, structural parameters of the bridge pile foundation structure, vibration velocity data under blasting, and stratigraphic parameters of the stratum where the bridge pile foundation structure is located; Establish the finite element overall model of the bridge pile foundation structure according to the on-site blasting parameters, structural parameters and stratum parameters; Based on the finite element model, the stress of the bridge pile foundation structure under blasting vibration is simulated to obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances; According to the correlation fitting between the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances, the safety control standard relationship between the maximum tensile stress and the maximum vibration velocity is obtained; Determine the maximum safe allowable vibration speed based on the preset maximum tensile stress design value and the safety control standard relationship; If the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm will be issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures.

[0027] In the embodiments of the present application, Figure 2 The safety control method of the bridge pile foundation structure under the influence of blasting vibration in the embodiment of the present application is described by taking the on-site construction schematic diagram as an example. Figure 2 The new bridge in the figure represents the bridge pile foundation structure, such as Figure 4 As shown, the bridge pile foundation structure specifically includes piers, caps and pile foundations.

[0028] In some embodiments, the on-site blasting parameters are: the average rock surface elevation of the right half of the channel (i.e., river channel) is about 19 m The blasting area is about 18184 The right half of the channel is required to be 40 meters away from the bridge pier. m Hydraulic crushing is used within the scope of construction, 40 m -150 m Controlled blasting is used within the scope. The planned single blasting length is about 25 m -30 m , using a step of 6 m The excavation was carried out by controlled blasting method, which was divided into 3 layers, with 6 layers on each layer. m Control, such as Figure 3The engineering blasting design is shown in Table 1. To ensure the safety of the bridge pier, the vibration velocity of the blasting construction monitoring point in this area should be less than 2.0 Monitoring point ( Figure 4 The deep hole step blasting is used as shown in Table 2.

[0029] Table 1 Engineering blasting design scheme

[0030] Table 2 Bench blasting parameters

[0031] According to the on-site engineering blasting design plan, the bench blasting parameter table and the arrangement of monitoring points, the blasting vibration velocity (i.e., vibration velocity data) and vibration frequency of the left and right bank monitoring points under blasting were obtained through blasting, as shown in Table 3.

[0032] Table 3 Blasting vibration velocity and frequency at monitoring points

[0033] In some embodiments of the present application, reference is made to Figure 5 and Figure 6 , structural parameters include concrete structure and steel structure, and stratum parameters include rock structure; based on the on-site blasting parameters, structural parameters and stratum parameters, a finite element overall model corresponding to the bridge pile foundation structure is established, including: The steel structure is divided into rod elements, and the concrete structure and rock structure are divided into hexahedron elements to obtain the initial finite element model; On the basis of the initial finite element model, the dynamic explicit elastic-plastic model is used to describe the mechanical properties of the concrete structure and the steel structure, and the elastic-plastic rock and soil constitutive model is used to describe the mechanical properties of the rock structure, thus obtaining the intermediate finite element model. The actual blasting load is determined according to the on-site blasting parameters, and the actual blasting load is loaded on the intermediate finite element model to obtain the overall finite element model.

[0034] It is understandable that the blasting excavation model mainly consists of three parts: the main bridge pile foundation (i.e., the bridge pile foundation structure), the ground layer, and the blasting source. The bridge pile foundation structure includes concrete and steel structures; the ground layer includes rock structures, which are silty clay, fully, strongly, and moderately weathered silty mudstone from top to bottom; based on the actual on-site construction conditions and blasting design, a total of 9 blasting source distances were considered (according to the blasting vibration control plan, the blasting source distance was 150 meters upstream and downstream of the bridge pile foundation structure). m 9 blasting source positions and 3 blasting depths (first to third step blasting) are set evenly within the range. Figure 6The material physical and mechanical parameters of the concrete structure, steel structure and rock structure are shown in Table 4.

[0035] Table 4 Physical and mechanical parameters of concrete, steel and rock structures

[0036] It should be noted that the specific conditions of the on-site blasting parameters mentioned in this embodiment and the above embodiments are merely examples and can be selected according to actual conditions, and should not be regarded as limitations on this application.

[0037] In some embodiments, the overall plane size of the bridge area blasting is 400 m 250 m In the model, other solid materials except the steel structure are divided by hexahedron elements, and the steel structure is divided by rod elements. The grid size is 50 to 400 The top of the model is a free surface, while the surrounding and bottom parts adopt non-reflecting boundary conditions to eliminate the influence of reflected waves to the greatest extent. Figure 5 shown.

[0038] As can be understood, the dynamic explicit elastoplastic model can describe both isotropic hardening and kinematic hardening plasticity models, and can also account for the effects of strain rate. It is applicable to beams, shells, and solid elements, is computationally efficient, and requires fewer parameters. The elastoplastic geotechnical constitutive model is an ideal elastoplastic model primarily used to simulate the mechanical behavior of geotechnical materials.

[0039] It should be noted that the specific principles and processes of using the dynamic explicit elastoplastic model and the elastoplastic rock and soil constitutive model to describe mechanical properties are existing technologies known to those skilled in the art and will not be described in detail here.

[0040] In some embodiments of the present application, determining the actual blasting load according to on-site blasting parameters includes: Establish a single blasthole model based on on-site blasting parameters; Apply elastic boundary to the inner wall of the blasthole model; The other blastholes are applied to the elastic boundary of a single blasthole model in the form of equivalent loads to obtain the actual blasting load.

[0041] Understandably, in practice, due to the large number of blastholes and their extremely small size compared to the overall model, detailed modeling of the blastholes would make calculations difficult. Therefore, an equivalent load is applied to the elastic boundary of the blasting excavation instead of the actual blasting load. The elastic boundary for the equivalent blasting load is the overall load within the blasthole arrangement.

[0042] It is very difficult to represent the true history of blasting dynamic loads. As a simple and effective alternative, triangular and double exponential curve loads have been widely adopted by scholars. This application uses triangular loads as the input form of equivalent loads.

[0043] According to the CJ theory of condensed explosive detonation wave, the initial average detonation pressure of the blast hole under coupled charge is for: ;Formula (1) in, is the initial average detonation pressure of the blast hole under the coupled charge, is the density of explosives, take =1000 , is the detonation velocity of explosive, take =3200 , is the explosive isentropic index, take =3.

[0044] When the load is applied to the elastic boundary after being equivalent, the corresponding equivalent load peak value is: ;Formula (2) in, is the equivalent load peak value, is the initial average detonation pressure of the blast hole under the coupled charge, is the blasthole radius, is the radius of the crushing zone, take =3 , is the radius of the crushing zone, =10 , is Poisson's ratio. The load boost time is 1 , action time is 8 .

[0045] According to the specific on-site blasting parameters, the initial average detonation pressure of the blasthole under the coupled charge (that is, the peak value of the explosion load on the blasthole wall) is calculated by formula (1) to be 1280 , the equivalent load peak value equivalent to the elastic boundary is calculated by formula (2) to be 13 .

[0046] It should be noted that the specific value of the equivalent load must be determined based on the actual on-site blasting parameters. The above calculation parameters are provided for illustrative purposes only and should not be construed as limiting this application. Furthermore, the calculation process and principles for equivalent loads using triangular loads are well known to those skilled in the art and will not be further elaborated upon here.

[0047] In some embodiments of the present application, reference is made to Figure 7 After establishing the finite element overall model of the bridge pile foundation structure according to the on-site blasting parameters, structural parameters and stratum parameters, it also includes: Obtain measured tensile stress data and measured vibration velocity data of bridge pile foundation structures; Based on the finite element overall model, the stress conditions of the bridge pile foundation structure under blasting vibration are simulated to obtain the simulated tensile stress data and simulated vibration velocity data of the bridge pile foundation structure under the influence of blasting vibration; The simulated tensile stress data and simulated vibration velocity data were compared with the measured tensile stress data and measured vibration velocity data to evaluate the effectiveness of the overall finite element model; When the effectiveness reaches the preset standard, the finite element overall model is executed to simulate the stress conditions of the bridge pile foundation structure under blasting vibration, and the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances are obtained.

[0048] In order to verify the validity of the established finite element model, the numerical simulation results were compared with the measured data of the monitoring point on the left bank, which is located at the pile foundation. , the maximum single-stage dosage is 12 , total explosive charge 768 , which is deep hole step blasting. The corresponding equivalent blasting load is set in the finite element overall model. Figure 7 The vibration time history curves of the foundation mass point obtained from on-site monitoring and the numerical simulation calculation results at the corresponding locations show that in the three vibration directions, the waveforms and peak values ​​obtained from the numerical simulation are highly consistent with the actual monitoring data.

[0049] It should be noted that the numerical simulation peaks earlier than the on-site monitoring data curve due to numerous influencing factors, including differences between the blasting site construction details and the numerical modeling, simplified topographic and geological modeling, and the assumption of uniform material mechanical parameters. However, the established finite element model still reasonably well reflects the dynamic response characteristics of the pile foundation under blasting excavation vibration. Therefore, this model can be used for further research and analysis.

[0050] In some embodiments of the present application, reference is made to Figure 8 、 Figure 9 and Figure 10 , the method further comprises: Based on the finite element overall model, the stress conditions of the bridge pile foundation structure under blasting vibration are simulated to obtain the tensile stress distribution and vibration velocity distribution of the bridge pile foundation structure under the influence of blasting vibration; Determine the dynamic stress distribution characteristics of the bridge pile foundation structure based on the tensile stress distribution; Determine the blasting vibration velocity distribution characteristics of the bridge pile foundation structure based on the vibration velocity distribution; The dynamic response characteristics of the bridge pile foundation structure are analyzed based on the dynamic stress distribution characteristics and blasting vibration velocity distribution characteristics, so as to achieve structural optimization of the bridge pile foundation structure according to the dynamic response characteristics.

[0051] Generally, for brittle materials such as concrete structures, their failure generally follows the maximum tensile stress criterion, that is, when the maximum tensile stress at a point in the structure exceeds its tensile strength, the structure is considered to have failed. Therefore, the maximum tensile stress is used below to describe the stress state of the pile foundation. The tensile stress data of the bridge pile foundation structure under the influence of blasting vibration are extracted from top to bottom along the lower structure to study the tensile stress distribution in the height direction under the influence of blasting vibration, such as Figure 8 As shown in the figure, the tensile stress of the pier column gradually increases from top to bottom and reaches the maximum at the junction of the pier column and the pedestal; the tensile stress of the pile foundation fluctuates in the depth direction due to the reflection and superposition of stress waves, and the maximum tensile stress is generated at the junction with the pile foundation, showing a stress concentration phenomenon. The tensile stress is the minimum and close to 0 at the bottom of the pile foundation.

[0052] The horizontal explosion center distance is 0 For example, the stress and vibration velocity responses of the bridge substructure under different layered blasting are as follows: Figure 9 As shown in the figure, it can be seen that the dynamic response of the lower structure caused by the first layer blasting is the strongest. With the blasting excavation of the second and third layers, the dynamic response of the lower structure gradually decreases. This is because the increase in the blasting source depth leads to an increase in the distance from the explosion center, and the excavation and removal of the upper rock mass affects the propagation of the blasting stress wave to the pile foundation.

[0053] While the maximum tensile stress criterion is the most intuitive and comprehensive way to determine structural failure under blasting vibration, monitoring dynamic stress in pile foundations under real-world conditions is difficult. Using peak particle velocity as a quantitative indicator of blasting vibration intensity is more convenient in practical engineering. Therefore, analyzing the distribution of peak particle velocity in pile foundations is fundamental to linking field monitoring data with pile foundation failure conditions.

[0054] Figure 10 The vibration velocity distribution of the bridge pile foundation structure from top to bottom is displayed. It can be seen that the vibration velocity of the pier column first decreases and then increases from top to bottom, and the vibration velocity of the pier column shows an elevation amplification effect at the top; the vibration velocity of the platform is basically consistent from top to bottom; the vibration velocity of the pile foundation first increases and then decreases from top to bottom, and the maximum vibration velocity occurs in the middle.

[0055] At the actual construction site, in order to facilitate monitoring readings, the blasting vibration sensor is generally placed on the foundation, and it is located just at the top of the foundation, and then it is used as the basic monitoring point for analysis.

[0056] In some embodiments of the present application, reference is made to Figure 11, the method further comprises: Based on the finite element overall model, the stress conditions of the bridge pile foundation structure under blasting vibration are simulated to obtain the tensile stress distribution of the bridge pile foundation structure under the influence of blasting vibration; Determine the target position corresponding to the maximum tensile stress of the bridge pile foundation structure based on the tensile stress distribution; The target location is determined as the vulnerable part of the bridge pile foundation structure to achieve reinforcement and protection of the vulnerable part.

[0057] Vibration waves generated by blasting propagate through the soil, affecting the structures surrounding the pile foundation. The dynamic stresses generated by blasting vibrations acting on the pile foundation can cause fatigue, cracks, displacement, and other damage to the pile material, impacting the overall stability of the bridge. When identifying vulnerable areas in bridge pile foundations, attention should be paid to the connection to the superstructure, where forces are concentrated and subject to various stresses, including tension, compression, and bending. In bridge pile foundations, especially under the influence of blasting vibrations, the middle and lower portions of the pile are susceptible to shear forces, resulting in cracks and fatigue damage.

[0058] In some embodiments, numerical simulation is used to simulate the stress of the bridge pile foundation structure under blasting vibration. During underground blasting, the vibration wave propagates in the soil, gradually spreading from the pile bottom to the pile body and then to the pile head, and gradually increases. The stress in the middle and lower part of the pile reaches its peak value and transfers along the upper part of the pile. When the maximum tensile stress on the pile body reaches its peak, it gradually decreases. When analyzing the maximum tensile stress on the bridge pile foundation structure, it reaches its maximum at the junction of the pier and the cap. Figure 11 As shown, at 0.6 Therefore, the upper part of the pile body should be paid special attention to, especially the junction between the pier and the cap, as this location is most affected by vibration and is the most vulnerable part of the bridge pile foundation structure.

[0059] In some embodiments of the present application, reference is made to Figure 12 Based on the finite element overall model, the stress conditions of the bridge pile foundation structure under blasting vibration are simulated, and the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances are obtained, including: Based on the finite element overall model, the stress conditions of the bridge pile foundation structure under blasting vibration were simulated, and the tensile stress distribution data and vibration velocity distribution data of the bridge pile foundation structure at different horizontal blast center distances were obtained; According to the tensile stress distribution data of the bridge pile foundation structure at different horizontal explosion center distances, the maximum tensile stress of the bridge pile foundation structure at different horizontal explosion center distances is determined; The maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances is determined based on the vibration velocity distribution data of the bridge pile foundation structure at different horizontal explosion center distances.

[0060] In some embodiments, Table 5 shows the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances: Table 5 Maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances

[0061] According to the data in Table 5, we can get Figure 12 In a specific embodiment, the maximum tensile stress design value is designed to be 1.43 According to the safety control standard relationship, the maximum safe allowable vibration speed is 3.2 , when the vibration speed data exceeds 3.2 In the event of a blast, an alarm will be issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures to ensure the safety of the bridge.

[0062] According to the safety control method for bridge pile foundation structures under the influence of blasting vibration in the embodiments of the present application, since monitoring the dynamic stress of pile foundations under real-world conditions is relatively difficult, the traditional method of judging the structural failure of bridge pile foundation structures under the influence of blasting vibration using the maximum tensile stress criterion is difficult to implement, resulting in inaccurate assessment results of the impact of blasting vibration on bridge pile foundation structures, making it difficult to ensure the safety of the bridge. This application establishes a finite element integral model corresponding to the bridge pile foundation structure and, based on the finite element integral model, simulates the stress conditions of the bridge pile foundation structure under blasting vibration, obtaining the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances, thereby solving the problem of the small number and scattered locations of real-world monitoring devices, making it difficult to obtain accurate maximum tensile stress and maximum vibration velocity. Then, by performing correlation fitting based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances, the safety control standard relationship between the maximum tensile stress and the maximum vibration velocity is obtained. Finally, the maximum safe allowable vibration velocity is determined based on the preset maximum tensile stress design value and the safety control standard relationship. When the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm is issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures. According to the maximum tensile stress criterion, the tensile stress is converted into the vibration velocity as a quantitative indicator to control the safety of the bridge pile foundation structure. This solves the problem that pile foundation dynamic stress monitoring under realistic conditions is difficult and the traditional method of judging the structural failure of the bridge pile foundation structure under the influence of blasting vibration by the maximum tensile stress criterion is difficult to carry out. It can accurately evaluate the impact of blasting vibration on the bridge pile foundation structure and ensure the safety of the bridge.

[0063] According to the safety control system of the bridge pile foundation structure under the influence of blasting vibration in the second aspect embodiment of the present application, the system includes a data acquisition unit, a finite element overall model establishment unit, a finite element simulation unit, a safety control standard relationship determination unit, a maximum safe allowable vibration speed determination unit and an alarm unit.

[0064] A data acquisition unit, used to acquire on-site blasting parameters, structural parameters of the bridge pile foundation structure and vibration velocity data under blasting, as well as stratum parameters of the stratum where the bridge pile foundation structure is located; The finite element overall model building unit is used to build the finite element overall model corresponding to the bridge pile foundation structure based on on-site blasting parameters, structural parameters and stratum parameters; The finite element simulation unit is used to simulate the stress of the bridge pile foundation structure under blasting vibration based on the finite element overall model, and obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances; A safety control standard relationship determination unit is used to perform correlation fitting based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances to obtain the safety control standard relationship between the maximum tensile stress and the maximum vibration velocity; A maximum safe allowable vibration speed determination unit is used to determine the maximum safe allowable vibration speed based on a preset maximum tensile stress design value and a safety control standard relationship; The alarm unit is used to sound an alarm when the vibration velocity data exceeds the maximum safe allowable vibration velocity, prompting the construction party to adjust the on-site blasting parameters or take protective measures.

[0065] According to the safety control system for bridge pile foundation structures under the influence of blasting vibration in the embodiment of the present application, since monitoring the dynamic stress of pile foundations under real-world conditions is relatively difficult, the traditional method of judging the structural failure of bridge pile foundation structures under the influence of blasting vibration using the maximum tensile stress criterion is difficult to implement, resulting in inaccurate assessment results of the impact of blasting vibration on bridge pile foundation structures, making it difficult to ensure the safety of the bridge. This application establishes a finite element integral model corresponding to the bridge pile foundation structure, and based on the finite element integral model, simulates the stress conditions of the bridge pile foundation structure under blasting vibration, and obtains the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances. This solves the problem of the small number and scattered locations of real-world monitoring devices, making it difficult to obtain accurate maximum tensile stress and maximum vibration velocity. Then, by performing correlation fitting based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal blast center distances, the safety control standard relationship between the maximum tensile stress and the maximum vibration velocity is obtained. Finally, the maximum safe allowable vibration velocity is determined based on the preset maximum tensile stress design value and the safety control standard relationship. When the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm is issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures. According to the maximum tensile stress criterion, the tensile stress is converted into the vibration velocity as a quantitative indicator to control the safety of the bridge pile foundation structure. This solves the problem that pile foundation dynamic stress monitoring under realistic conditions is difficult and the traditional method of judging the structural failure of the bridge pile foundation structure under the influence of blasting vibration by the maximum tensile stress criterion is difficult to carry out. It can accurately evaluate the impact of blasting vibration on the bridge pile foundation structure and ensure the safety of the bridge.

[0066] Since the safety control system of the bridge pile foundation structure under the influence of blasting vibration adopts all the technical solutions of the safety control method of the bridge pile foundation structure under the influence of blasting vibration of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, and will not be repeated here.

[0067] In addition, an embodiment of the present application further provides a control device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor and the memory may be connected via a bus or other means.

[0068] The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0069] The non-transient software program and instructions required to implement the safety control method for bridge pile foundation structure under the influence of blasting vibration in the above embodiment are stored in the memory. When executed by the processor, the safety control method for bridge pile foundation structure under the influence of blasting vibration in the above embodiment is executed.

[0070] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, i.e., they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment.

[0071] In addition, an embodiment of the present application also provides a computer-readable storage medium, which stores computer-executable instructions. The computer-executable instructions are executed by a processor or controller, for example, by the processor of the above embodiment, so that the above processor can execute the safety control method of the bridge pile foundation structure under the influence of blasting vibration in the above embodiment.

[0072] Those skilled in the art will appreciate that all or some of the steps and systems disclosed above can be implemented as software, firmware, hardware, or any suitable combination thereof. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on computer-readable media, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is well known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVDs) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0073] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A safety control method for a bridge pile foundation structure under the influence of blasting vibration, characterized in that: The method comprises: Acquiring on-site blasting parameters, structural parameters of the bridge pile foundation structure, vibration velocity data under blasting, and stratum parameters of the stratum where the bridge pile foundation structure is located; Establishing a finite element integral model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters and the stratum parameters; Based on the finite element overall model, the stress condition of the bridge pile foundation structure under blasting vibration is simulated to obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure under different horizontal blast center distances; Correlation fitting is performed based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances to obtain a safety control standard relationship between the maximum tensile stress and the maximum vibration velocity; Determine the maximum safe allowable vibration speed based on the preset maximum tensile stress design value and the safety control standard relationship; If the vibration velocity data exceeds the maximum safe allowable vibration velocity, an alarm is issued to prompt the construction party to adjust the on-site blasting parameters or take protective measures.

2. The safety control method for bridge pile foundation structure under the influence of blasting vibration according to claim 1 is characterized in that: The structural parameters include concrete structure and steel structure, and the stratum parameters include rock mass structure; The step of establishing a finite element integral model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters, and the stratum parameters includes: The steel structure is divided using rod elements, and the concrete structure and the rock structure are divided using hexahedron elements to obtain an initial finite element model; Based on the initial finite element model, a dynamic explicit elastic-plastic model is used to describe the mechanical properties of the concrete structure and the steel structure, and an elastic-plastic rock and soil constitutive model is used to describe the mechanical properties of the rock structure, thereby obtaining an intermediate finite element model; An actual blasting load is determined according to the on-site blasting parameters, and the actual blasting load is loaded on the intermediate finite element model to obtain the overall finite element model.

3. The safety control method for bridge pile foundation structure under the influence of blasting vibration according to claim 2 is characterized in that: The determining of the actual blasting load according to the on-site blasting parameters includes: establishing a single blasthole model according to the on-site blasting parameters; Applying an elastic boundary to the inner wall of the blasthole model; The other blast holes are applied to the elastic boundary of the single blast hole model in the form of equivalent loads to obtain the actual blasting load.

4. The safety control method for bridge pile foundation structure under the influence of blasting vibration according to claim 1 is characterized in that: The method of simulating the stress of the bridge pile foundation structure under blasting vibration based on the finite element overall model to obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure under different horizontal blast center distances includes: Based on the finite element overall model, the stress condition of the bridge pile foundation structure under blasting vibration is simulated to obtain the tensile stress distribution data and vibration velocity distribution data of the bridge pile foundation structure under different horizontal blast center distances; determining the maximum tensile stress of the bridge pile foundation structure at different horizontal explosion center distances according to the tensile stress distribution data of the bridge pile foundation structure at different horizontal explosion center distances; The maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances is determined according to the vibration velocity distribution data of the bridge pile foundation structure at different horizontal explosion center distances.

5. The safety control method for bridge pile foundation structure under the influence of blasting vibration according to claim 1 is characterized in that: The method further comprises: Based on the finite element overall model, the stress condition of the bridge pile foundation structure under the blasting vibration is simulated to obtain the tensile stress distribution of the bridge pile foundation structure under the influence of the blasting vibration; Determining a target position corresponding to a maximum tensile stress on the bridge pile foundation structure according to the tensile stress distribution; The target position is determined as a vulnerable part of the bridge pile foundation structure to achieve reinforcement and protection of the vulnerable part.

6. The safety control method for bridge pile foundation structure under the influence of blasting vibration according to claim 1 is characterized in that: After establishing the finite element integral model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters and the stratum parameters, the method further includes: Obtaining measured tensile stress data and measured vibration velocity data of the bridge pile foundation structure; Based on the finite element overall model, simulating the stress condition of the bridge pile foundation structure under the influence of blasting vibration, and obtaining simulated tensile stress data and simulated vibration velocity data of the bridge pile foundation structure under the influence of blasting vibration; Comparing and verifying the simulated tensile stress data and the simulated vibration velocity data with the measured tensile stress data and the measured vibration velocity data to evaluate the validity of the finite element overall model; When the effectiveness reaches the preset standard, the finite element overall model is executed to simulate the stress condition of the bridge pile foundation structure under blasting vibration, and the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure under different horizontal explosion center distances are obtained.

7. The safety control method for bridge pile foundation structure under the influence of blasting vibration according to claim 1 is characterized in that: The method further comprises: Based on the finite element overall model, the stress condition of the bridge pile foundation structure under the blasting vibration is simulated to obtain the tensile stress distribution and vibration velocity distribution of the bridge pile foundation structure under the influence of the blasting vibration; determining the dynamic stress distribution characteristics of the bridge pile foundation structure according to the tensile stress distribution; determining a blasting vibration velocity distribution characteristic of the bridge pile foundation structure according to the vibration velocity distribution; The dynamic response characteristics of the bridge pile foundation structure are analyzed based on the dynamic stress distribution characteristics and the blasting vibration velocity distribution characteristics, so as to achieve structural optimization of the bridge pile foundation structure according to the dynamic response characteristics.

8. A safety control system for a bridge pile foundation structure under the influence of blasting vibration, characterized in that: The system comprises: a data acquisition unit, configured to acquire on-site blasting parameters, structural parameters of the bridge pile foundation structure, vibration velocity data under blasting, and stratum parameters of the stratum where the bridge pile foundation structure is located; a finite element overall model building unit, configured to build a finite element overall model corresponding to the bridge pile foundation structure according to the on-site blasting parameters, the structural parameters, and the stratum parameters; A finite element simulation unit is used to simulate the stress condition of the bridge pile foundation structure under blasting vibration based on the finite element overall model, and obtain the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure under different horizontal blast center distances; a safety control standard relationship determination unit, configured to perform correlation fitting based on the maximum tensile stress and maximum vibration velocity of the bridge pile foundation structure at different horizontal explosion center distances to obtain a safety control standard relationship between the maximum tensile stress and the maximum vibration velocity; a maximum safe allowable vibration speed determining unit, configured to determine the maximum safe allowable vibration speed based on a preset maximum tensile stress design value and the safety control standard relationship; The alarm unit is used to issue an alarm when the vibration velocity data exceeds the maximum safe allowable vibration velocity, prompting the construction party to adjust the on-site blasting parameters or take protective measures.

9. A control device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method for safety control of a bridge pile foundation structure under the influence of blasting vibration as described in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing computer-executable instructions, characterized in that: The computer-executable instructions are used to execute the safety control method for a bridge pile foundation structure under the influence of blasting vibration as described in any one of claims 1 to 7.

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