Multi-modal pushover test method and system for deep underground structures based on hybrid test

Abstract

The present invention discloses a multi-modal pushover test system for deep underground structures based on hybrid tests, which belongs to the technical field of underground structure tests. The test system includes a numerical substructure composed of a numerical model of a deep underground structure and a part of the surrounding soil removed, and a test substructure composed of a large-scale stratum-deep underground structure pushover model test designed according to the removed part and a free field model composed of a one-dimensional soil column numerical model, which are respectively connected to the numerical substructure. The present invention also provides a multi-modal pushover test method for deep underground structures based on hybrid tests. The present invention integrates numerical simulation and model tests through hybrid test technology, which can provide more accurate mechanical boundary conditions for pushover tests, thereby being able to well reproduce the initial ground stress state of the deep underground structure while introducing the influence of high-order modes, and also overcome the problem of the traditional pushover test technology that the loading plate and the soil are detached during the loading process.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground structure testing, and in particular relates to a multi-modal pushover testing method and system for deep underground structures based on a hybrid test. Background Art

[0002] At present, underground engineering has been widely used in rail transit, municipal engineering and other fields, and underground engineering construction has entered a period of rapid development. Due to the characteristics of underground structures being relatively closed, difficult to repair structural damage, and irreversible engineering construction, underground structures have been damaged in many previous earthquakes, causing significant loss of life and property. Therefore, it is of great significance to clarify the damage mechanism and failure mode of underground structures under earthquakes and provide theoretical support for the seismic performance design of underground structures.

[0003] However, due to the strong uncertainty and instantaneity of earthquake occurrence, and the fact that underground structures are completely hidden underground, it is difficult to fully record the destruction process of underground structures under earthquake action. It is difficult to effectively analyze the disaster-causing mechanism of underground structures based on post-earthquake on-site observations alone. Therefore, it is necessary to conduct model test research that can observe and record the development laws of the mechanical behavior of underground structures throughout the entire process. Pushover tests are a simple and effective way to analyze the seismic weaknesses of structures and their nonlinear behaviors, and are widely used in the study of seismic performance of underground structures.

[0004] Since the underground structure is constrained by the surrounding soil, there is a complex interaction between the structure and the soil. This effect needs to be considered when conducting pushover tests on underground structures. Therefore, it is necessary to conduct pushover tests on the stratum-underground structure system. The traditional pushover test on underground structures applies lateral displacements with inverted triangle distribution and increasing values ​​to the stratum-underground structure system, so that the structure gradually enters the elastic-plastic stage, or even completely destroys it, in order to obtain the evolution law of the nonlinear mechanical behavior of the structure under earthquake. Therefore, only the influence of the first-order mode can be considered. In addition, the pushover method with displacement as the target requires the same displacement of the lateral loading plate at the same height. Since the soil has a certain shear resistance, the passive side loading plate will be emptied from the soil during the loading process, causing the stress state of the stratum-underground structure system to be distorted. The pushover method with load as the target will always keep the loading plate in close contact with the soil to ensure the authenticity of the stress state of the stratum-underground structure system. In combination with a multi-degree-of-freedom box device, the pushover of the stratum-underground structure system under high mode can be accurately achieved.

[0005] At the same time, deep underground structures, in addition to being subject to high earth pressure, often use dark excavation methods during construction, which will inevitably cause stratum loss around the structure, making the initial stress state of the deep underground structure very complicated. In this regard, the pile loading method and other methods commonly used in the pushover test of shallow underground structures are difficult to simulate the initial stress state of the stratum-deep underground structure system. Since the initial stress state of the deep underground structure has a significant impact on the seismic performance of the structure itself, it is necessary to adopt an appropriate method to simulate the initial stress state, and force-controlled loading can easily achieve this requirement.

[0006] Therefore, it is necessary to propose a test method and corresponding system architecture suitable for deep underground structures, which can not only simulate the initial stress state of deep underground structures, but also reflect the influence of high-order vibration modes on the seismic performance of underground structures, and take load as the loading target to prevent the loading plate from being decoupled from the soil. Summary of the invention

[0007] The present invention discloses a multi-modal pushover test method and system for deep underground structures based on hybrid tests. The method can apply a pushover load based on numerical calculation to the model test, accurately simulate the initial stress state, consider the influence of high-order modes, and avoid the void between the soil and the loading plate during the pushover process, so as to obtain a more realistic damage evolution process and destruction mechanism of the deep underground structure under the action of earthquake, provide theoretical support for the seismic design of the deep underground structure, and thus effectively solve at least one technical problem involved in the background technology.

[0008] To achieve the above object, the technical solution of the present invention is:

[0009] A multi-modal pushover test system for deep underground structures based on hybrid tests, comprising a numerical substructure composed of a numerical model of a deep underground structure and a portion of surrounding soil removed, and a test substructure composed of a large-scale stratum-deep underground structure pushover model test designed according to the removed portion and a free field model composed of a one-dimensional soil column numerical model, respectively connected to the numerical substructure, wherein:

[0010] The free field model is used to provide the numerical substructure with the target pushover displacements and horizontal body force distribution forms of each mode required in the pushover analysis stage;

[0011] The numerical substructure is used to provide mechanical boundary conditions for the test substructure in the gravity analysis stage and the pushover stage;

[0012] The test substructure applies load under mechanical boundary conditions, and feeds back the mechanical response of the deep underground structure and the surrounding soil to the numerical substructure to assist subsequent numerical calculations.

[0013] As a preferred improvement of the present invention, the data interaction between the numerical substructure and the experimental substructure is realized through the connection mode of OpenFresco-LabVIEW-servo control system, wherein OpenFresco embeds the client unit in the numerical substructure to provide a stable communication interface for information interaction between the two substructures, and the format conversion in the data interaction process is realized through LabVIEW.

[0014] The present invention also provides a multi-modal pushover test method for deep underground structures based on a hybrid test, comprising the following steps:

[0015] Step 1: Based on the structural information of the deep underground structure and the site information, the test substructure is designed, and on this basis, the free field model and numerical substructure are established using numerical analysis software. Then, seismic waves are selected according to the needs, and the site analysis under the target ground motion is carried out on the free field model to obtain the corresponding response of the site under each mode;

[0016] Step 2: Based on the free field response, calculate the horizontal body force distribution form and target overturning displacement under each mode in the overturning stage;

[0017] Step 3, divide the gravity analysis process into multiple stages, apply the gravity load of the first stage to the numerical substructure, obtain the mechanical boundary conditions of the test substructure in the first stage of gravity analysis, and simultaneously perform the same gravity analysis on the free field model;

[0018] Step 4: Based on the mechanical boundary conditions calculated by the numerical substructure, the ground stress state of the test substructure in the gravity analysis stage is simulated by the actuator based on force control, and the actual loading displacement of the actuator reflecting the mechanical response of the structure is obtained through the sensor;

[0019] Step 5, the actual loading displacement of the actuator is fed back to the numerical substructure and substituted into the numerical calculation of the next stage as an additional boundary condition to obtain the mechanical boundary conditions required for the test substructure of the next stage of gravity analysis;

[0020] Step 6, repeat steps 4 to 5 until the gravity analysis is completed, completing the simulation of the initial ground stress state of the test substructure;

[0021] Step 7, the pushover analysis process is divided into multiple stages, and the first stage horizontal body force is applied to the numerical substructure and free field model that have completed the gravity analysis according to the horizontal body force distribution form under a certain order mode, so as to obtain the mechanical boundary conditions of the first stage of pushover analysis of the test substructure that has completed the initial geostress simulation under the order mode;

[0022] Step 8, based on the mechanical boundary conditions calculated by the numerical substructure, the stress state of the test substructure in the pushover analysis stage is simulated by the actuator based on force control, and the actual loading displacement of the actuator reflecting the mechanical response of the structure is obtained through the sensor;

[0023] Step 9, the actual loading displacement of the actuator is fed back to the numerical substructure and substituted into the numerical calculation of the next stage as an additional boundary condition to obtain the mechanical boundary conditions required for the test substructure of the next stage of pushover analysis;

[0024] Step 10, repeating steps 8 to 9 until the horizontal displacement of the top of the free-field model of synchronous pushover reaches the target pushover displacement under the corresponding mode, and completing the pushover test under the mode;

[0025] Step 11: Repeat steps 3 to 10 to complete the pushover test under other modes.

[0026] As a preferred improvement of the present invention, in step 2, the horizontal body force distribution is the product of the mass distribution of the free field model and the modal vibration shape, and the target overthrow displacement is the maximum horizontal displacement of the free field top under each mode.

[0027] As a preferred improvement of the present invention, the mechanical boundary conditions include boundary displacement and boundary force data.

[0028] As a preferred improvement of the present invention, the structural mechanical response includes actuator force and displacement.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. The present invention integrates the advantages of numerical simulation and model test through hybrid test technology. Based on the interaction between the test substructure and the numerical substructure, it can avoid modeling of the deep underground structure and its surrounding soil layer, which is difficult to solve, and replace it with the real results of the model test. Since the data fed back by the test substructure sensor can reflect the structural damage and the interaction between the stratum and the structure, the calculation efficiency and accuracy of the numerical substructure are greatly improved, which can provide more accurate mechanical boundary conditions for the pushover test of the deep underground structure.

[0031] 2. Based on the mechanical boundary conditions calculated by numerical substructure, loading is performed through force control to carry out multi-modal pushover tests on deep underground structures and their surrounding soil layers. This can prevent the separation of soil and loading plates caused by displacement loading, and accurately reproduce the stress state of deep underground structures.

[0032] 3. The numerical substructure that continuously interacts with the test substructure can quickly and accurately solve the mechanical boundary conditions required for each stage of the pushover test, so that the pushover test of deep underground structures based on the hybrid test can effectively consider the influence of initial ground stress and high-order modes;

[0033] 4. The test substructure consisting of large-scale stratum-deep underground structure pushover model tests can well reflect the interaction between stratum and structure and the nonlinear damage evolution of the structure. The test process can be monitored in real time, which is convenient for analyzing the damage mechanism of deep underground structures under earthquakes and providing theoretical support for the seismic design of deep underground structures.

[0034] 5. The existence of the free field model provides the target pushover displacement and horizontal body force distribution corresponding to each mode, while ensuring that the displacement field of the numerical substructure is consistent with the actual displacement field, avoiding the solution of the target pushover load required for the numerical substructure, and achieving both accuracy and convenience;

[0035] 6. The connection method of OpenFresco-LabVIEW-servo control system can replace the servo control system according to the experimental conditions of different laboratories, and it has strong portability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0037] Figure 1 One of the flow charts of a multi-modal pushover test system for deep underground structures based on a hybrid test provided by the present invention;

[0038] Figure 2 The second flowchart of a multi-modal pushover test system for deep underground structures based on a hybrid test provided by the present invention;

[0039] Figure 3 A flow chart of a multi-modal pushover test method for deep underground structures based on a hybrid test provided by the present invention. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] like Figure 1 As shown, the present invention provides a multi-modal pushover test system for deep underground structures based on hybrid tests, including a numerical substructure 1 composed of a numerical model of a deep underground structure and part of the surrounding soil removed, a free field model 2 composed of a one-dimensional soil column numerical model respectively connected to the numerical substructure 1, and a test substructure 3 composed of a large-scale stratum-deep underground structure pushover model test designed according to the deep underground structure and part of the surrounding soil.

[0046] Among them, the data interaction mode between the numerical substructure 1 and the free field model 2 is a one-way data interaction, and the free field model 2 is used to provide the numerical substructure 1 with the target overturning displacement and horizontal body force distribution form under each mode required in the overturning analysis stage.

[0047] The data interaction mode between the numerical substructure 1 and the test substructure 3 is bidirectional data interaction. The numerical substructure 1 is used to provide the test substructure 3 with the initial stress state and the mechanical boundary conditions of the overthrow stage; the test substructure 3 applies load under the mechanical boundary conditions, and feeds back the mechanical response of the deep underground structure and its surrounding soil to the numerical substructure 1 to assist subsequent numerical calculations.

[0048] Specific, combined Figure 2 As shown, the data exchange of boundary displacement and boundary force between the numerical substructure 1 and the test substructure 3 is realized by the connection mode of OpenFresco-LabVIEW-servo control system. Among them, OpenFresco provides a stable communication interface for information exchange between the two substructures by embedding the client unit in the numerical substructure, and the format conversion in the data exchange process is realized by LabVIEW.

[0049] The present invention also provides a deep underground structure multi-modal pushover test method based on a hybrid test based on the deep underground structure multi-modal pushover test system based on a hybrid test, combined with Figure 3 As shown, the following steps are included:

[0050] Step 1: Based on the structural information of the deep shield tunnel and the site information, a large-scale stratum-deep underground structure pushover model test is designed and used as the test substructure; on this basis, the OpenSees finite element software is used to establish a one-dimensional soil column model from the bedrock to the surface and a two-dimensional stratum model excluding the area involved in the test substructure, which are used as a free field model and a numerical substructure respectively; then, the target intensity seismic wave is selected according to the needs, and a one-dimensional site analysis is carried out on the free field model under the target seismic motion to obtain the corresponding response of the site under each mode.

[0051] Among them, the large-scale stratum-deep underground structure pushover model test as the test substructure has a scale ratio of 1:12, including the shield tunnel and the surrounding soil; the numerical substructure model size is 120m×125m, and the free field model size is 5m×125m; the deep shield tunnel has an outer diameter of 6m and a burial depth of 70m. In the numerical substructure, the tunnel and the surrounding soil are removed, totaling 16m×16m, and replaced with OpenFresco client units.

[0052] Step 2: Based on the free field response, calculate the horizontal body force distribution form and target overturning displacement under each mode in the overturning stage;

[0053] Specifically, the horizontal body force distribution is the product of the mass distribution of the free field model and the modal vibration shape, and the target pushover displacement is the maximum horizontal displacement of the free field top under each mode.

[0054] Step 3, divide the gravity analysis process into ten stages, apply the gravity load of the first stage to the numerical substructure, obtain the mechanical boundary conditions of the test substructure in the first stage of gravity analysis, and simultaneously perform the same gravity analysis on the free field model;

[0055] Step 4: Based on the mechanical boundary conditions calculated by the numerical substructure, the ground stress state of the test substructure in the gravity analysis stage is simulated by the actuator based on force control, and the actual loading displacement of the actuator is obtained through the sensor; wherein, the displacement can reflect the influence of structural mechanical response such as stratum-structure interaction and structural damage;

[0056] Step 5, the actual loading displacement of the actuator is fed back to the numerical substructure and substituted into the numerical calculation of the next stage as an additional boundary condition to obtain the mechanical boundary conditions required for the test substructure of the next stage of gravity analysis;

[0057] Step 6, repeat steps 4 to 5 until the gravity analysis is completed, completing the simulation of the initial ground stress state of the test substructure;

[0058] Step 7, the pushover analysis process is divided into twenty stages, and the horizontal body force of the first stage is applied to the numerical substructure and free field model that have completed the gravity analysis according to the horizontal body force distribution form under the first-order mode, so as to obtain the mechanical boundary conditions of the first stage of pushover analysis of the test substructure that has completed the initial ground stress state simulation under the first-order mode;

[0059] Step 8, based on the mechanical boundary conditions calculated by the numerical substructure, the stress state of the test substructure in the pushover analysis stage is simulated by the actuator based on force control, and the actual loading displacement of the actuator is obtained through the sensor;

[0060] Step 9, the actual loading displacement of the actuator is fed back to the numerical substructure and substituted into the numerical calculation of the next stage as an additional boundary condition to obtain the mechanical boundary conditions required for the test substructure of the next stage of pushover analysis;

[0061] Step 10, repeat steps 8 to 9 until the horizontal displacement of the top of the free-field model of synchronous pushover reaches the target pushover displacement under the corresponding mode. It can be considered that the test substructure has completed the pushover test under the first-order mode at this time;

[0062] Step 11, repeat steps 3 to 10 to complete the pushover test under the second and third modes.

[0063] Specifically, the mechanical boundary conditions include boundary displacement and boundary force data, and the structural mechanical response includes actuator force and displacement.

[0064] The beneficial effects of the present invention are as follows:

[0065] 1. The present invention integrates the advantages of numerical simulation and model test through hybrid test technology. Based on the interaction between the test substructure and the numerical substructure, it can avoid modeling of the deep underground structure and its surrounding soil layer, which is difficult to solve, and replace it with the real results of the model test. Since the data fed back by the test substructure sensor can reflect the structural damage and the interaction between the stratum and the structure, the calculation efficiency and accuracy of the numerical substructure are greatly improved, which can provide more accurate mechanical boundary conditions for the pushover test of the deep underground structure.

[0066] 2. Based on the mechanical boundary conditions calculated by numerical substructure, loading is performed through force control to carry out multi-modal pushover tests on deep underground structures and their surrounding soil layers. This can prevent the separation of soil and loading plates caused by displacement loading, and accurately reproduce the stress state of deep underground structures.

[0067] 3. The numerical substructure that continuously interacts with the test substructure can quickly and accurately solve the mechanical boundary conditions required for each stage of the pushover test, so that the pushover test of deep underground structures based on the hybrid test can effectively consider the influence of initial ground stress and high-order modes;

[0068] 4. The test substructure consisting of large-scale stratum-deep underground structure pushover model tests can well reflect the interaction between stratum and structure and the nonlinear damage evolution of the structure. The test process can be monitored in real time, which is convenient for analyzing the damage mechanism of deep underground structures under earthquakes and providing theoretical support for the seismic design of deep underground structures.

[0069] 5. The existence of the free field model provides the target pushover displacement and horizontal body force distribution corresponding to each mode, while ensuring that the displacement field of the numerical substructure is consistent with the actual displacement field, avoiding the solution of the target pushover load required for the numerical substructure, and achieving both accuracy and convenience;

[0070] 6. The connection method of OpenFresco-LabVIEW-servo control system can replace the servo control system according to the experimental conditions of different laboratories, and it has strong portability.

[0071] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A multi-modal pushover test method for deep underground structures based on a hybrid test, characterized in that: The following steps are involved: Step 1: Based on the structural information of the deep underground structure and the site information, the test substructure is designed, and on this basis, the free field model and numerical substructure are established using numerical analysis software. Then, seismic waves are selected according to the needs, and the site analysis under the target ground motion is carried out on the free field model to obtain the corresponding response of the site under each mode; Step 2: Based on the free field response, calculate the horizontal body force distribution form and target overturning displacement under each mode in the overturning stage; Step 3, divide the gravity analysis process into multiple stages, apply the gravity load of the first stage to the numerical substructure, obtain the mechanical boundary conditions of the test substructure in the first stage of gravity analysis, and simultaneously perform the same gravity analysis on the free field model; Step 4: Based on the mechanical boundary conditions calculated by the numerical substructure, the ground stress state of the test substructure in the gravity analysis stage is simulated by the actuator based on force control, and the actual loading displacement of the actuator reflecting the mechanical response of the structure is obtained through the sensor; Step 5, the actual loading displacement of the actuator is fed back to the numerical substructure and substituted into the numerical calculation of the next stage as an additional boundary condition to obtain the mechanical boundary conditions required for the test substructure of the next stage of gravity analysis; Step 6, repeat steps 4 to 5 until the gravity analysis is completed, completing the simulation of the initial ground stress state of the test substructure; Step 7, the pushover analysis process is divided into multiple stages, and the first stage horizontal body force is applied to the numerical substructure and free field model that have completed the gravity analysis according to the horizontal body force distribution form under a certain order mode, so as to obtain the mechanical boundary conditions of the first stage of pushover analysis of the test substructure that has completed the initial geostress simulation under the order mode; Step 8, based on the mechanical boundary conditions calculated by the numerical substructure, the stress state of the test substructure in the pushover analysis stage is simulated by the actuator based on force control, and the actual loading displacement of the actuator reflecting the mechanical response of the structure is obtained through the sensor; Step 9, the actual loading displacement of the actuator is fed back to the numerical substructure and substituted into the numerical calculation of the next stage as an additional boundary condition to obtain the mechanical boundary conditions required for the test substructure of the next stage of pushover analysis; Step 10, repeating steps 8 to 9 until the horizontal displacement of the top of the free-field model of synchronous pushover reaches the target pushover displacement under the corresponding mode, and completing the pushover test under the mode; Step 11: Repeat steps 3 to 10 to complete the pushover test under other modes.

2. A multi-modal pushover test method for deep underground structures based on a hybrid test according to claim 1, characterized in that: In step 2, the horizontal body force distribution is the product of the mass distribution of the free field model and the modal vibration shape, and the target pushover displacement is the maximum horizontal displacement of the top of the free field under each mode.

3. A multi-modal pushover test method for deep underground structures based on a hybrid test according to claim 2, characterized in that: The mechanical boundary conditions include boundary displacement and boundary force data.

4. A multi-modal pushover test method for deep underground structures based on a hybrid test according to claim 2, characterized in that: The structural mechanical response includes actuator forces and displacements.

5. The multi-modal pushover test method for deep underground structures based on hybrid test according to claim 1 is characterized in that: The free field model is used to provide the numerical substructure with the target pushover displacements and horizontal body force distribution forms of each mode required in the pushover analysis stage.

6. A multi-modal pushover test method for deep underground structures based on a hybrid test according to claim 5, characterized in that: The numerical substructure is used to provide mechanical boundary conditions for the test substructure in the gravity analysis stage and the pushover stage, and the test substructure is used to provide additional boundary conditions for the numerical substructure in the next stage.

7. A multi-modal pushover test method for deep underground structures based on a hybrid test according to claim 6, characterized in that: The data interaction between the numerical substructure and the experimental substructure is realized through the connection mode of OpenFresco-LabVIEW-servo control system, wherein OpenFresco embeds the client unit in the numerical substructure to provide a stable communication interface for information interaction between the two substructures, and the format conversion during the data interaction process is realized through LabVIEW.

8. The multi-modal pushover test method for deep underground structures based on hybrid test according to claim 1 is characterized in that: The numerical substructure consists of a numerical model with the deep underground structure and part of the surrounding soil removed, the experimental substructure consists of a large-scale stratum-deep underground structure pushover model test designed according to the removed part, and the free-field model consists of a one-dimensional soil column numerical model; the free-field model and the experimental substructure are respectively connected to the numerical substructure.

Images