Soft rock tunnel primary support structure stress time-dependent prediction and early warning method and related products

Abstract

The present application relates to the technical field of tunnel and underground engineering, and particularly relates to a soft rock tunnel primary support structure stress time-effect prediction and early warning method and related products, comprising establishing a surrounding rock-primary support structure interaction mechanical model considering the rheological properties of soft rock, obtaining time-varying support resistance based on the mechanical model, obtaining the ultimate support resistance of the primary support structure, comparing the time-varying support resistance with the ultimate support resistance in real time, and issuing a safety warning signal when the time-varying support resistance reaches or exceeds the ultimate support resistance; the present application fully considers the influence of the rheological properties of soft rock and the delayed construction of the primary support, can accurately predict the change rule of the primary support structure stress with time, and provides a scientific basis for the safe construction and long-term stability evaluation of soft rock tunnels.

Description

Technical Field

[0001] This invention relates to the field of tunnel and underground engineering technology, specifically to a method for predicting and early warning of the stress timeliness of the initial support structure of a soft rock tunnel and related products, which is particularly applicable to engineering scenarios that consider the rheological characteristics of soft rock and the delayed construction of support. Background Technology

[0002] In soft rock tunnel construction, controlling the stability of the surrounding rock is crucial for construction safety. Due to the significant rheological properties of soft rock, its mechanical behavior changes dramatically over time, leading to a continuous increase in the load on the initial support structure. Traditional support design methods are mostly based on elastic or elastoplastic theories, failing to fully consider the impact of time effects on the stress on the support structure, especially neglecting the displacement accumulation and stress redistribution problems caused by delayed construction of the initial support structure.

[0003] Traditional analytical methods are mostly based on elastic or elastoplastic theories, often treating the surrounding rock and support as a static system, failing to fully consider the impact of time effects on the support stress. In actual engineering operations, there is an objective time interval between excavation and support construction (i.e., support delay), during which some displacement of the surrounding rock has already occurred. Ignoring this delayed construction effect will lead to a significant deviation between the theoretically calculated support load and the actual stress state. In existing technologies, although some studies have attempted to introduce rheological models to analyze the interaction between the surrounding rock and support, these are mostly limited to theoretical derivations and lack practical methods for real-time prediction and early warning combined with specific engineering parameters.

[0004] Regarding early warning mechanisms at engineering sites, existing methods largely rely on feedback from on-site monitoring data. This makes it difficult to effectively extrapolate the stress growth trend of the support structure over a future period, nor can it accurately predict when the support structure will reach its bearing limit. This makes it difficult for construction workers to obtain sufficient time to reinforce the support or adjust construction procedures before structural failure, posing a potential safety hazard to tunnel construction. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a method for predicting and warning the stress timeliness of the initial support structure of soft rock tunnels and related products. This method can comprehensively consider the rheological characteristics of soft rock and the effect of delayed support construction, and realize the active prediction and dynamic warning of the stress state of the initial support structure.

[0006] This invention is achieved through the following technical solution:

[0007] A method for predicting and early warning of the stress timeliness of the initial support structure of a soft rock tunnel includes the following steps:

[0008] A mechanical model of the interaction between the surrounding rock and the initial support structure is established, taking into account the rheological properties of soft rock. The surrounding rock is considered as a viscoelastic material, and the initial support structure is considered as a linear elastic material.

[0009] Based on the aforementioned mechanical model, the time-varying support resistance is obtained;

[0010] Obtain the ultimate support resistance of the initial support structure;

[0011] The time-varying support resistance is compared with the ultimate support resistance in real time. When the time-varying support resistance reaches or exceeds the ultimate support resistance, a safety warning signal is issued.

[0012] Optionally, the mechanical model is an axisymmetric plane strain model, including the following physical boundary condition assumptions: the initial ground stress in all directions of the tunnel is... The tunnel has a circular cross-section, and the initial support structure is an annular structure. The interface between the tunnel wall and the initial support structure is in smooth contact, and the shear stress at the interface is zero.

[0013] Optionally, the initial support structure includes shotcrete and a steel arch frame;

[0014] The equivalent cross-sectional area of ​​the initial support structure : ;

[0015] The equivalent elastic modulus of the initial support structure : ;

[0016] in, , These are the elastic modulus and cross-sectional area of ​​the shotcrete, respectively. , These are the elastic modulus and cross-sectional area of ​​the steel arch frame, respectively.

[0017] Optionally, the rheological constitutive equation of the surrounding rock is: In the formula, For stress, In response, , These are the shear moduli of Maxwellian and Kelvinian forms, respectively. , The viscosity coefficients of Maxwellian and Kelvinian systems, respectively. , , , These are the first and second derivatives of stress and strain, respectively.

[0018] Alternatively, methods for obtaining time-varying support resistance include:

[0019] Establish a deformation coordination relationship equation at the interface between the tunnel wall and the initial support structure. The deformation coordination relationship equation satisfies that the radial displacement increment of the surrounding rock caused by the initial ground stress after the support is installed, the reverse radial displacement caused by the support resistance, and the radial displacement of the initial support structure itself reach a displacement balance.

[0020] The Laplace transform of the deformation compatibility equation is applied to obtain the Laplace transform corresponding to the time-varying support resistance. Then, the time-varying support resistance in the time domain is derived through the inverse Laplace transform. .

[0021] Optionally, the deformation compatibility equation is: ,in, This represents the increase in radial displacement of the tunnel wall caused by the initial ground stress after the initial support structure is constructed. Indicates time-varying support resistance The resulting reverse radial displacement of the surrounding rock, Indicates the time-varying support resistance The reaction force generates radial displacement on the initial support structure.

[0022] Optionally, radial displacement increment : ,in, This indicates the time elapsed after the initial support structure was constructed. This indicates the delay time between tunnel excavation and the construction of the initial support structure. Indicates in The radial displacement of the tunnel wall caused by the initial ground stress at all times. Indicates in The radial displacement of the tunnel wall caused by the initial ground stress at any given moment.

[0023] Optionally, the time-varying support resistance : ,in, For initial ground stress, As an intermediate variable; , , ;

[0024] In the formula, , These are the shear moduli of Maxwellian and Kelvinian forms, respectively. , The viscosity coefficients of Maxwellian and Kelvinian systems, respectively. To delay the construction time of the initial support structure. The radius of the tunnel excavation. The initial support structure thickness, The Poisson's ratio of the initial support structure. It is the equivalent elastic modulus of the initial support structure.

[0025] Optionally, after issuing a safety warning signal, the following steps are also included:

[0026] Based on the safety warning signal, the initial support structure of the soft rock tunnel is reinforced, or the timing of the initial support structure construction during subsequent tunnel construction is adjusted.

[0027] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method for predicting and warning the stress timeliness of the initial support structure of a soft rock tunnel as described above.

[0028] A computer program product includes a computer program / instructions that, when executed by a processor, implement the method for predicting and warning the stress duration of the initial support structure of a soft rock tunnel as described above.

[0029] Compared with the prior art, the present invention has the following features and beneficial effects:

[0030] This invention constructs a mechanical model of the interaction between the surrounding rock and the initial support structure, and uses the Laplace transform and inverse transform methods to solve the mechanical equations, derives and calculates the time-varying support resistance, and then establishes a real-time comparison mechanism between the resistance and the ultimate support resistance of the initial support structure to trigger an early warning.

[0031] This invention quantifies the impact of support lag on the release of stress in the surrounding rock by introducing a delayed application time into the rock-support interaction model. This eliminates the calculation deviation of support load caused by the assumption of "instantaneous support" in traditional elastic or viscoelastic theories. Therefore, the derived analytical expression of time-varying support resistance can more realistically reflect the objective law of the stress on the support structure in soft rock tunnels increasing over time. Then, the derived time-varying support resistance is compared with the ultimate support resistance, thereby knowing in advance the time node when the support structure may fail, avoiding sudden collapse accidents caused by the accumulation of rheological loads exceeding the limit.

[0032] This invention fully considers the rheological properties of soft rock and the influence of delayed initial support construction, and can accurately predict the stress change law of the initial support structure over time, providing a scientific basis for the safe construction and long-term stability assessment of soft rock tunnels. Attached Figure Description

[0033] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0034] Figure 1 This is a flowchart illustrating a method for predicting and warning the stress timeliness of the initial support structure of a soft rock tunnel according to the present invention.

[0035] Figure 2 This is a schematic diagram of the mechanical model of the tunnel surrounding rock-initial support structure according to the present invention.

[0036] Figure 3 This is the finite element calculation model for the ultimate support resistance of the initial support structure according to the present invention.

[0037] Figure 4 This is a schematic diagram of the real-time stress state early warning assessment of the initial support structure according to the present invention.

[0038] Figure 5 This is a schematic diagram illustrating the curve of support resistance changing over time and the determination of the warning time point in Embodiment 3 of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0040] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0041] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] Example 1

[0043] like Figure 1 As shown in the figure, this embodiment provides a method for predicting and warning the time-dependent stress effect of the initial support structure of a soft rock tunnel. By theoretically modeling and quantifying the dynamic load of the surrounding rock on the support structure over time, and comparing it with the bearing limit of the support structure itself, proactive safety warning is achieved.

[0044] The steps are explained in detail below:

[0045] Step 1: Establish a mechanical model of the interaction between the surrounding rock and the initial support structure, taking into account the rheological properties of soft rock. The surrounding rock is considered as a viscoelastic material, and the initial support structure is considered as a linear elastic material.

[0046] Viscoelasticity refers to the properties of surrounding rock materials that combine those of fluids and solids. After excavation, the deformation of the surrounding rock does not occur instantaneously, but rather creep or stress relaxation occurs over time.

[0047] Linear elasticity refers to the relationship between stress and strain in a supported structure, which follows Hooke's Law, meaning that deformation is instantaneous and proportional to the applied force.

[0048] Step 2: Based on the mechanical model, obtain the time-varying support resistance; the time-varying support resistance refers to the reaction force generated by the support structure to resist the deformation of the surrounding rock, which gradually increases with the accumulation of the rheological deformation of the surrounding rock.

[0049] Step 3: Obtain the ultimate support resistance of the initial support structure; the ultimate support resistance refers to the maximum support reaction force that the initial support structure can provide before reaching a failure state (such as concrete crushing or steel arch yielding). It is independent of time and depends only on the material strength, geometry (thickness, cross-section, etc.) and combination of the support structure.

[0050] Step 4: Compare the time-varying support resistance with the ultimate support resistance in real time. When the time-varying support resistance reaches or exceeds the ultimate support resistance, the support structure is already overburdened and faces the risk of failure. At this time, a safety warning signal needs to be issued.

[0051] Step 5: Based on the safety warning signal, the engineers reinforce the initial support structure of the soft rock tunnel, or adjust the timing of the initial support structure construction during subsequent tunnel construction.

[0052] Example 2

[0053] This embodiment provides a detailed description of the steps in Embodiment 1.

[0054] Step 1: Establish an axisymmetric plane strain mechanical model of the interaction between the surrounding rock and the initial support structure, including the following physical boundary condition assumptions: the initial in-situ stress in all directions of the tunnel is... The tunnel has a circular cross-section and an excavation radius of [missing information]. The initial support structure is a ring with a thickness of [missing information]. Furthermore, the interface between the tunnel wall and the initial support structure is in smooth contact, and the shear stress at the interface is zero. See the surrounding rock-initial support structure model. Figure 2 .

[0055] The initial support structure includes shotcrete and a steel arch frame, and the elastic constitutive equation of the initial support structure is: , The equivalent elastic modulus of the initially supported structure. , The equivalent cross-sectional area of ​​the initial support structure is... ;in, , These are the elastic modulus and cross-sectional area of ​​the shotcrete, respectively. , These are the elastic modulus and cross-sectional area of ​​the steel arch frame, respectively.

[0056] The rheological constitutive equation of the surrounding rock is: In the formula, For stress, In response, , These are the shear moduli of Maxwellian and Kelvinian forms, respectively. , The viscosity coefficients of Maxwellian and Kelvinian systems, respectively. , , , These are the first and second derivatives of stress and strain, respectively.

[0057] Step 2: When both the surrounding rock and the initial support structure are elastic materials, the support resistance at the interface between the tunnel wall and the initial support structure is determined. It is a constant and does not change with time. The radial displacement of the surrounding rock at the tunnel wall is caused by the initial in-situ stress. Radial displacement generated under action and support resistance Reverse radial displacement generated under action The components are superimposed; the radial displacement generated by the initial support structure at the tunnel wall is the support resistance. Radial displacement generated by the reaction of the initial support The expressions for different displacements are as follows: .

[0058] In soft rock tunnel engineering, considering the rheological properties of soft rock, the stress and displacement of the tunnel surrounding rock and support structure will change over time, affecting the support resistance. It becomes a non-constant that changes over time. , , , They respectively become time-varying. , , This timeliness has a significant impact on the stability and safety of the tunnel. Furthermore, the initial support structure is often constructed some time after tunnel excavation. Let's assume the initial support structure is constructed after tunnel excavation (full-section excavation, completed instantaneously). Construction continues continuously, from the excavation of the tunnel surrounding rock to... During this period, the tunnel is unsupported, and the radial displacement of the tunnel wall is determined solely by the initial ground stress. Generate, represented as After a period of time Afterwards, initial ground stress The resulting radial displacement is Support resistance The resulting reverse radial displacement is Support resistance The radial displacement generated by the reaction force on the initial support is Throughout the process, the following deformation coordination relationship is always satisfied at the interface between the tunnel wall and the initial support structure: the radial displacement increment of the surrounding rock caused by the initial ground stress after the support is installed, the reverse radial displacement caused by the support resistance, and the radial displacement of the initial support structure itself are in equilibrium.

[0059] The deformation compatibility equation is: ,in, This represents the increase in radial displacement of the tunnel wall caused by the initial ground stress after the initial support structure is constructed. Indicates time-varying support resistance The resulting reverse radial displacement of the surrounding rock, Indicates the time-varying support resistance The reaction force generates radial displacement on the initial support structure.

[0060] Radial displacement increment : ,in, This indicates the time elapsed after the initial support structure was constructed. This indicates the delay time between tunnel excavation and the construction of the initial support structure. Indicates in The radial displacement of the tunnel wall caused by the initial ground stress at all times. Indicates in The radial displacement of the tunnel wall caused by the initial ground stress at any given moment.

[0061] According to the principle of elastic-viscoelastic correspondence, the radial displacement of viscoelastic surrounding rock and elastic initial support at the tunnel wall can be expressed as: In the formula, Indicates time The differential operator has .

[0062] Substituting the above equation into the deformation compatibility equation and performing a Laplace transformation The Laplace transform corresponding to the time-varying support resistance is obtained by solving the problem. , This represents the Laplace transform operation. .

[0063] Then, the time-varying support resistance in the time domain is derived using the inverse Laplace transform. The time-varying support resistance : ,in, For initial ground stress, As an intermediate variable; , b and c need to satisfy ;

[0064] In the formula, , These are the shear moduli of Maxwellian and Kelvinian forms, respectively. , The viscosity coefficients of Maxwellian and Kelvinian systems, respectively. To delay the construction time of the initial support structure. The radius of the tunnel excavation. The initial support structure thickness, The Poisson's ratio of the initial support structure. It is the equivalent elastic modulus of the initial support structure.

[0065] Step 3: Establish a load-structure model using finite element software, see... Figure 3 The maximum support resistance that different initial support structure combinations (combinations of different grades and thicknesses of shotcrete with different types of steel arch frames) can provide when the bearing limit is reached is calculated, and a database of ultimate support resistance of initial support structures is constructed.

[0066] Step 4: Based on time-varying support resistance Ultimate support force of the support structure The comparison, if If this is detected, an early warning message will be issued, thereby enabling timely prediction and early warning of the stress state of the initial support structure, such as... Figure 4 As shown.

[0067] Step 5: Based on the specific conditions at the engineering site, the response measures after the early warning are mainly divided into immediate remediation and subsequent optimization.

[0068] Support reinforcement: Engineers must immediately reinforce the hazardous area. Common reinforcement methods include adding radial anchors to distribute the pressure from the surrounding rock, applying shotcrete to increase the support thickness, or erecting temporary steel supports.

[0069] Further optimization: Based on the early warning feedback, the construction delay time of the initial support structure in the subsequent construction section will be adjusted.

[0070] Example 3

[0071] This embodiment uses a soft rock tunnel project as a background to provide a specific example.

[0072] 1. Project Overview and Parameter Settings

[0073] Initial ground stress of tunnel The pressure is 2.5 MPa, and the excavation radius is... The initial support structure is 2.5m high. C25 shotcrete with a thickness of 30cm is used, and the steel arch frame is type I22b, spaced 0.8m per frame. The physical and mechanical parameters of the initial support structure are shown in Table 1.

[0074] Table 1 Physical and mechanical parameters of the initial support structure

[0075] The physical and mechanical parameters of the surrounding rock of the tunnel are shown in Table 2.

[0076] Table 2 Physical and mechanical parameters of the surrounding rock

[0077] 2. Implementation Steps

[0078] Step 1: Establish a mechanical model

[0079] According to the method of the present invention, an axisymmetric plane strain mechanical model of the interaction between the surrounding rock and the initial support structure is established.

[0080] Step 2: Solve for time-varying support resistance

[0081] Considering the delayed construction of the initial support structure after tunnel excavation (in this embodiment) Based on the displacement coordination relationship between the support and the surrounding rock interface, the time-varying support resistance at the interface between the tunnel wall and the initial support structure is obtained by using Laplace transform and inverse transform.

[0082] Step 3: Determine the ultimate support resistance of the support structure

[0083] Using ANSYS finite element method software, the ultimate support resistance of the selected initial support structure combination (C25 shotcrete, 30cm thick + I22b steel arch frame, spacing 0.8m / frame) in this embodiment was calculated. According to the calculation, the ultimate support resistance corresponding to this equivalent initial support structure is... .

[0084] Step 4: Timeliness Prediction and Safety Early Warning

[0085] By comparing the time-varying support resistance calculated in step two with the ultimate support resistance determined in step three, dynamic prediction and safety early warning of the stress state of the initial support structure can be achieved.

[0086] 3. Results and Analysis

[0087] The calculated curve of time-varying support resistance versus time is shown below. Figure 5 As shown. By Figure 5 It can be known that:

[0088] After the initial support structure is constructed, under the influence of the rheological properties of the weak surrounding rock, the structure bears the surrounding rock pressure. It gradually increases over time.

[0089] At t=214h, the surrounding rock pressure borne by the initially supported structure The ultimate load of the initially supported structure was reached. .

[0090] At this point, it can be determined that the stress on the initial support structure has reached its design compressive strength value, and the initial support structure is about to fail, thus issuing a warning signal.

[0091] 4. Conclusion

[0092] This embodiment verifies the effectiveness and practicality of the method described in this invention in predicting the stress duration and providing safety early warning for the initial support structure of soft rock tunnels. This method can accurately reflect the rheological properties of soft rock and the impact of delayed support construction, providing reliable technical support for the dynamic design and safety control of tunnel engineering.

[0093] Example 4

[0094] A computer-readable storage medium storing a computer program, characterized in that, when executed by a processor, the computer program implements the method for predicting and warning the stress timeliness of the initial support structure of a soft rock tunnel as described above.

[0095] Without loss of generality, computer-readable media can include computer storage media and communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented using any method or technology for storing information such as computer-readable instruction data structures, program modules, or other data. Computer storage media includes RAM, ROM, EPROM, EEPROM, flash memory or other solid-state storage technologies, CD-ROM, DVD or other optical storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices. Of course, those skilled in the art will recognize that computer storage media are not limited to the above-mentioned types. The aforementioned system memories and mass storage devices can be collectively referred to as memory.

[0096] A computer program product includes a computer program / instructions that, when executed by a processor, implement the method for predicting and warning the stress duration of the initial support structure of a soft rock tunnel as described above.

[0097] Computer program products include computer programs or instruction sets used to perform specific tasks or achieve specific functions. These programs or instructions are designed to be executed by a processor to implement a series of predefined steps or operations. The program product may be stored in various forms of computer storage media, such as memory, hard disks, solid-state drives, optical discs, or other forms of digital storage devices. It may exist in the form of compiled binary code or in the form of scripts or bytecode that can be executed by an interpreter. Through carefully designed algorithms and logical instructions, the program product enables the processor to process data in a specific order and manner, performing various functions such as data analysis, user interaction, and device control.

[0098] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0099] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0100] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A method for predicting and early warning the stress timeliness of the initial support structure of a soft rock tunnel, characterized in that, Includes the following steps: A mechanical model of the interaction between the surrounding rock and the initial support structure is established, taking into account the rheological properties of soft rock. The surrounding rock is considered as a viscoelastic material, and the initial support structure is considered as a linear elastic material. Based on the aforementioned mechanical model, the time-varying support resistance is obtained; Obtain the ultimate support resistance of the initial support structure; The time-varying support resistance is compared with the ultimate support resistance in real time. When the time-varying support resistance reaches or exceeds the ultimate support resistance, a safety warning signal is issued. The methods for obtaining time-varying support resistance include: Establish a deformation coordination relationship equation at the interface between the tunnel wall and the initial support structure. The deformation coordination relationship equation satisfies that the radial displacement increment of the surrounding rock caused by the initial ground stress after the support is installed, the reverse radial displacement caused by the support resistance, and the radial displacement of the initial support structure itself reach a displacement balance. The Laplace transform of the deformation compatibility equation is applied to obtain the Laplace transform corresponding to the time-varying support resistance. Then, the time-varying support resistance in the time domain is derived through the inverse Laplace transform. ; The deformation compatibility equation is as follows: ,in, This represents the increase in radial displacement of the tunnel wall caused by the initial ground stress after the initial support structure is constructed. Indicates time-varying support resistance The resulting reverse radial displacement of the surrounding rock, Indicates the time-varying support resistance The radial displacement generated by the reaction force on the initial support structure; Radial displacement increment : ,in, This indicates the time elapsed after the initial support structure was constructed. This indicates the time delay between tunnel excavation and the construction of the initial support structure. Indicates in The radial displacement of the tunnel wall caused by the initial ground stress at all times. Indicates in The radial displacement of the tunnel wall caused by the initial ground stress at any given moment.

2. The method for predicting and early warning of the stress timeliness of the initial support structure of a soft rock tunnel according to claim 1, characterized in that, The mechanical model is an axisymmetric plane strain model, including the following physical boundary condition assumptions: the initial in-situ stress in all directions of the tunnel is... The tunnel has a circular cross-section, and the initial support structure is an annular structure. The interface between the tunnel wall and the initial support structure is in smooth contact, and the shear stress at the interface is zero.

3. The method for predicting and early warning of the stress timeliness of the initial support structure of a soft rock tunnel according to claim 2, characterized in that, The initial support structure includes shotcrete and steel arch frame; The equivalent cross-sectional area of ​​the initial support structure : ; The equivalent elastic modulus of the initial support structure : ; in, , These are the elastic modulus and cross-sectional area of ​​the shotcrete, respectively. , These are the elastic modulus and cross-sectional area of ​​the steel arch frame, respectively.

4. The method for predicting and early warning of the stress timeliness of the initial support structure of a soft rock tunnel according to claim 2, characterized in that, The rheological constitutive equation of the surrounding rock is: In the formula, For stress, In response, , These are the shear moduli of Maxwellian and Kelvinian forms, respectively. , The viscosity coefficients of Maxwellian and Kelvinian systems, respectively. , , , These are the first and second derivatives of stress and strain, respectively.

5. The method for predicting and early warning of the stress timeliness of the initial support structure of a soft rock tunnel according to claim 1, characterized in that, The time-varying support resistance : ,in, For initial ground stress, As an intermediate variable; , , ; In the formula, , These are the shear moduli of Maxwellian and Kelvinian forms, respectively. , The viscosity coefficients of Maxwellian and Kelvinian systems, respectively. To delay the construction time of the initial support structure. The radius of the tunnel excavation. The initial support structure thickness, For the initial support structure, Poisson's ratio, It is the equivalent elastic modulus of the initial support structure.

6. The method for predicting and early warning of the stress timeliness of the initial support structure of a soft rock tunnel according to claim 1, characterized in that, After issuing a safety warning signal, the following steps are also included: Based on the safety warning signal, the initial support structure of the soft rock tunnel is reinforced, or the timing of the initial support structure construction during subsequent tunnel construction is adjusted.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the method for predicting and warning the stress timeliness of the initial support structure of soft rock tunnel as described in any one of claims 1-6.

8. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the method for predicting and warning the stress timeliness of the initial support structure of soft rock tunnel as described in any one of claims 1-6.

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