Deformation Response-Based Method and Apparatus for Assessing the Service Status of Tunnel Lining

Abstract

This invention provides a method and apparatus for evaluating the service status of tunnel lining based on deformation response. After the tunnel is put into operation, without calculating the increment or total amount of surrounding rock pressure or load after operation, it is possible to determine the lining crack width and safety factor, and evaluate or analyze the secondary lining service status and its variation law at any service time of the tunnel. The method includes: Step 1, determining the displacement increment u2 of the tunnel from the time of commissioning or acceptance to a certain tunnel maintenance time t under the service status; Step 2, establishing a load structure model of the tunnel; Step 3, applying displacement directly to the load structure model based on the displacement increment u2, fixing constraints on all element nodes, and calculating the internal forces of the structure; Step 4, obtaining the safety factor and crack width of the element based on the internal forces of the element; Step 5, evaluating the service status of the tunnel at the tunnel maintenance time t based on the safety factor and crack width.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel engineering design, and particularly relates to a tunnel lining service state evaluation method and device based on deformation response. BACKGROUND

[0002] Mountain tunnels of railways and highways generally adopt composite support structures of primary support plus secondary lining. According to different surrounding rock grades, the surrounding rock pressure caused by tunnel excavation is jointly borne by the primary support and the secondary lining in a certain proportion. During the service process of the tunnel, the primary support will gradually deteriorate and fail due to the comprehensive action of underground water, corrosive soil and other factors, thereby causing the surrounding rock pressure acting on the secondary lining to continuously increase, the safety factor of the secondary lining to continuously decrease, and the crack width to continuously expand, which seriously threatens the service safety of the tunnel.

[0003] Since the surrounding rock pressure is a selected monitoring item and is only monitored during the construction process of tunnels with high ground stress or special needs, the surrounding rock pressure and the change rule of the secondary lining during the service period cannot be obtained for almost all tunnels, and thus the service state of the tunnel in the use stage cannot be accurately evaluated. A large number of tunnels rapidly deteriorate due to the lack of timely and effective evaluation and disposal, which greatly reduces the reliability and durability of the tunnel service and brings serious safety hazards to the tunnel service.

[0004] When the secondary lining of the tunnel appears obvious apparent diseases, crack information thereof, including crack distribution, quantity, length, width and seepage water state, can be obtained through various detection means, and the diseases are classified according to the severity and corresponding disposal measures are developed. This maintenance and management method has the following deficiencies:

[0005] 1) When the tunnel appears obvious apparent diseases, the service performance of the lining has already been greatly degraded, and the disposal measures taken at this time are insufficient in timeliness.

[0006] 2) The diseases detection of crack width and seepage water has large investment and low efficiency, and cannot intuitively reflect the service performance of the tunnel and is insufficient in pertinence.

[0007] 3) The disease classification is difficult to analyze and obtain the change rule of the service performance of the tunnel, and the service state of the tunnel section without obvious apparent diseases cannot be evaluated.

[0008] Therefore, under the condition that the tunnel does not appear obvious diseases, the service performance evaluation is carried out according to the displacement change of the tunnel, which has urgent practical needs and important engineering significance. SUMMARY

[0009] This invention is made to solve the above-mentioned problems and aims to provide a method and apparatus for evaluating the service status of tunnel lining based on deformation response. After the tunnel is put into operation, the lining crack width and safety factor can be determined without calculating the increment or total amount of surrounding rock pressure or load after operation. The secondary lining service status and its change law at any service time of the tunnel can be evaluated or analyzed.

[0010] To achieve the above objectives, the present invention adopts the following solution:

[0011] <Method>

[0012] This invention provides a method for assessing the service condition of tunnel linings based on deformation response, characterized by comprising the following steps:

[0013] Step 1: Determine the displacement increment u2 of the tunnel from the time it is put into operation or accepted to a certain tunnel maintenance time t when the tunnel is in service.

[0014] Explanation: After tunnel excavation, stress release will generate surrounding rock pressure, which will be borne by the lining. According to the principle of convergence constraint, under the combined action of the lining's self-weight and the surrounding rock pressure, the lining structure will deform, and the displacement of the tunnel when it reaches equilibrium is u1; then, as... Figure 1 As shown, as the tunnel is accepted and put into operation, the initial lining support capacity will decrease, leading to lining deformation. The displacement increment of the secondary lining of the tunnel from the time of tunnel acceptance or operation until the tunnel reaches the maintenance period t is u2.

[0015] Step 2: Establish the load structure model of the tunnel;

[0016] Step 3: On the load structure model, instead of calculating and applying the increment or total amount of surrounding rock pressure, the displacement is directly applied based on the displacement increment u2, and all element nodes are fixedly constrained to calculate the internal forces of the structure.

[0017] This invention makes special improvements to the conventional tunnel load structure model: such as Figure 3 The conventional load-bearing structural model shown requires the calculation and use of surrounding rock pressure variation data for the secondary lining. Furthermore, the determined surrounding rock pressure distribution is approximate (it needs to be assumed based on the depth of burial), and may deviate from the actual situation. Therefore, the resulting state indicators are difficult to accurately reflect the tunnel's service condition. Figure 4 As shown, the method of the present invention does not require determining the surrounding rock pressure change data of the secondary lining, but directly obtains the state index based on the displacement. This not only greatly reduces the difficulty of data acquisition and simplifies the calculation process, but also avoids the error caused by assuming the surrounding rock pressure distribution. The calculation results are more accurate and can more realistically reflect the service status of the tunnel.

[0018] Step 4, according to the internal force of the structure of the unit, the safety factor and the crack width of the unit are obtained;

[0019] Step 5, according to the safety factor and the crack width, the service state of the tunnel at the tunnel maintenance time t is evaluated.

[0020] Preferably, the tunnel lining service state evaluation method based on deformation response provided by the present application can further have the following characteristics: in step 1, the three-dimensional laser scanner is used to obtain the cross-section shape data of the tunnel at the time of putting into operation and the cross-section shape data at the tunnel maintenance time t, and then the displacement increment u2 is determined. At the time of engineering acceptance, the three-dimensional laser scanner is usually used to scan the tunnel cross-section at a certain position and output the tunnel cross-section shape. When the tunnel operation reaches the maintenance period t, the scanner is used to scan the tunnel cross-section at the same position and output the cross-section shape.

[0021] Preferably, the tunnel lining service state evaluation method based on deformation response provided by the present application can further have the following characteristics: in step 2, the ANSYS software is used to establish a tunnel load structure model; in step 3, the displacement increment u2 is used to fix the constraint of all unit nodes, and then the internal force of the structure is output by the ANSYS software. The tunnel load structure model can be established according to the size and parameters of the tunnel, and the total displacement u=u1+u2 is directly applied to the tunnel structure, as shown in the following formula: Figure 2 The internal force of the structure is obtained by fixing the constraint of all unit nodes, or the u2 is further applied to update the model based on the existing u1 model to obtain the internal force of the structure; the u1 is obtained by the prior art, and will not be described herein.

[0022] Preferably, the tunnel lining service state evaluation method based on deformation response provided by the present application can further have the following characteristics: in step 5, the safety factor and the crack width calculated are compared with the limit state threshold value, and then the service state of the tunnel lining is evaluated; on this basis, combined with the actual engineering, whether the tunnel cracks appear water seepage or not, corresponding reinforcement measures are formulated to ensure that the tunnel can be operated safely for a long time. The limit state threshold value can be the specified value in the Railway Tunnel Design Specification (Limit State Method) Q / CR9129-2018.

[0023] <Device>

[0024] Further, the present application also provides a tunnel lining service state evaluation device based on deformation response, characterized in that it comprises:

[0025] A displacement increment determination unit determines the displacement increment u2 of the tunnel generated from the time of putting into operation to a certain tunnel maintenance time t under the service state of the tunnel;

[0026] The model construction unit establishes a load structure model of the tunnel;

[0027] The displacement application calculation unit, on the load structure model, does not calculate and apply the surrounding rock pressure increment or total amount, but directly applies displacement based on the displacement increment u2, fixes constraints for all element nodes, and calculates the internal force of the structure;

[0028] The parameter obtaining unit obtains the safety factor and crack width of the element according to the internal force of the element structure;

[0029] The evaluation unit evaluates the service state of the tunnel at the tunnel maintenance time t according to the safety factor and crack width;

[0030] The control unit is in communication with the displacement increment determination unit, the model construction unit, the displacement application calculation unit, the parameter obtaining unit, and the evaluation unit, and controls the operation of them.

[0031] Preferably, the tunnel lining service state evaluation device based on deformation response provided by the application can further comprise a reinforcement measure generation unit in communication with the control unit, obtaining the service state evaluation result of the tunnel lining and information about whether the cracks of the tunnel in the actual project appear to be water seepage, and generating a reinforcement scheme for the corresponding position of the tunnel according to the same.

[0032] Preferably, the tunnel lining service state evaluation device based on deformation response provided by the application can further comprise an input display unit in communication with the displacement increment determination unit, the model construction unit, the displacement application calculation unit, the parameter obtaining unit, the evaluation unit, the reinforcement measure generation unit, and the control unit, for letting the user input operation instructions and performing corresponding display.

[0033] Preferably, the tunnel lining service state evaluation device based on deformation response provided by the application can further have the following features: the input display unit can display the displacement increment u2 determined by the displacement increment determination unit, display the load structure model established by the model construction unit, display the process and data of applying the displacement increment u2 to the internal force of the structure by the displacement application calculation unit, display the safety factor and crack width of the element obtained by the parameter obtaining unit and the evaluation result of the service state by the evaluation unit at the corresponding position of the model, and display the reinforcement scheme generated by the reinforcement measure generation unit in association with the service state evaluation result and information about whether the cracks of the tunnel in the actual project appear to be water seepage at the corresponding position of the tunnel. Preferably, the tunnel lining service state evaluation device based on deformation response provided by the application can further have the following features: the displacement increment determination unit obtains the cross-sectional shape data of the tunnel when it is put into operation and the cross-sectional shape data of the tunnel at the tunnel maintenance time t by using a three-dimensional laser scanner, and then determines the displacement increment u2.

[0034] Preferably, the tunnel lining service state evaluation device based on deformation response provided by the application can further have the features that the model construction unit is used to establish a tunnel load structure model by using ANSYS software, and the displacement application calculation unit is used to calculate the internal force of the structure by fixing the constraints of all element nodes through the ANSYS software.

[0035] Effects of the application

[0036] The tunnel lining service state evaluation method and device based on deformation response provided by the application first determine the displacement increment u2 of the tunnel in the service state from the time when the tunnel is put into operation or acceptance to the tunnel maintenance time t, and then obtain the internal force of the structure according to the displacement increment u2 and the established tunnel load structure model, without calculating, applying and using any surrounding rock pressure or load, and further obtain the safety factor distribution and crack width distribution of the tunnel lining according to the internal force of the structure, so as to evaluate and analyze the service state and change rule of the tunnel at the tunnel maintenance time t. The application can be effectively used to analyze and determine the lining service state at any service time of the tunnel, and make up for the deficiency that the existing technology can only evaluate the service state at the initial time. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The lining deformation graph related to the application;

[0038] Figure 2 The tunnel constraint graph related to the application;

[0039] Figure 3 The prior art principle graph related to the embodiment of the application;

[0040] Figure 4 The method principle graph of the application related to the embodiment of the application;

[0041] Figure 5 The flowchart of the tunnel lining service state evaluation method based on deformation response related to the embodiment of the application;

[0042] Figure 6 The tunnel lining numerical model graph related to the first embodiment of the application;

[0043] Figure 7 The forced displacement and constraint application graph related to the first embodiment of the application;

[0044] Figure 8 The tunnel bending moment graph (N·m) related to the first embodiment of the application;

[0045] Figure 9 The tunnel axial force graph (N) related to the first embodiment of the application;

[0046] Figure 10This is a diagram illustrating the tunnel safety factor according to Embodiment 1 of the present invention;

[0047] Figure 11 The crack width (mm) involved in Embodiment 1 of the present invention;

[0048] Figure 12 This is a diagram of node displacement in the x-direction according to Embodiment 2 of the present invention;

[0049] Figure 13 This is a diagram of node displacement in the y-direction according to Embodiment 2 of the present invention;

[0050] Figure 14 This is a diagram illustrating the forced displacement and node constraints involved in Embodiment 2 of the present invention;

[0051] Figure 15 This is a tunnel axial force diagram (N) according to Embodiment 2 of the present invention;

[0052] Figure 16 This is a diagram of the tunnel bending moment (N·m) according to Embodiment 2 of the present invention;

[0053] Figure 17 This is a diagram illustrating the tunnel safety factor according to Embodiment 2 of the present invention;

[0054] Figure 18 This is a diagram (mm) showing the width of a tunnel crack in Embodiment 2 of the present invention. Detailed Implementation

[0055] The following detailed description, with reference to the accompanying drawings, of the specific implementation schemes of the tunnel lining service condition assessment method and apparatus based on deformation response, which relates to the present invention. In the following embodiments, the analysis software involved is FLAC. 3D Unless otherwise specified, the steps and methods involved are all conventional methods.

[0056] <Example 1>

[0057] In this embodiment, a railway tunnel with a speed of 160 km / h is selected. It is a deep-buried tunnel with a span of 11.6 m and a surrounding rock grade of V. Material parameters are shown in Table 1. The lining uses C35 strength concrete, and both the inner and outer sides use HRB335 strength steel bars. The calculated vertical surrounding rock pressure is 168 kPa. Reinforcement parameters are shown in Table 2, steel bar parameters in Table 3, and concrete parameters in Table 4.

[0058] Table 1 Material Parameters

[0059]

[0060] Table 2 Reinforcement Parameters

[0061]

[0062] Table 3 Parameters of HRB335 steel bars

[0063]

[0064] Table 4 Concrete Parameters

[0065]

[0066] like Figure 5 As shown, the tunnel lining service status assessment method based on deformation response adopted in this embodiment includes the following steps:

[0067] Step 1: Use a 3D laser scanner to obtain cross-sectional shape data of the tunnel when it is put into operation and cross-sectional shape data at time t during tunnel maintenance, and then determine the displacement increment u2 of the tunnel secondary lining.

[0068] Step 2: Establish the tunnel load structure model using ANSYS software. In this embodiment, the numerical model of the lining is established based on the tunnel geometry as follows: Figure 6 As shown.

[0069] Step 3: On the load-bearing structural model, instead of calculating and applying the increment or total amount of surrounding rock pressure, the displacement is directly applied based on the displacement increment u2, such as... Figure 7 As shown, in this embodiment, the total tunnel displacement u = u1 + u2 is directly applied to each node of the tunnel structure, and all element nodes are fixedly constrained. Then, the internal forces of the structure are directly calculated using ANSYS software. The obtained element bending moments and axial forces are shown below. Figure 8 and 9 As shown.

[0070] Step 4: Based on the structural internal forces of the unit, obtain the safety factor and crack width of the unit; combining the function of the ultimate limit state and serviceability limit state of the concrete rectangular section bearing capacity, obtain the safety factor distribution and crack width distribution of the lining unit under the two working conditions, as shown below. Figure 10 and 11 As shown.

[0071] The internal forces, safety factors, crack widths, and other state indicators of the tunnel lining obtained by the method of this invention were compared with the actual measured conditions of the tunnel. The results were consistent, indicating that it is feasible to use the method of this invention to obtain state indicators for evaluating the service status of the tunnel when the surrounding rock pressure cannot be obtained.

[0072] Step 5: Evaluate the tunnel's service status at tunnel maintenance time t based on the safety factor and crack width. In this embodiment, based on the minimum safety factor of the tunnel unit being 2.7, which is greater than the standard requirement of 2.4, and the maximum crack width being 0.15mm, which is less than the standard requirement of 0.2mm, it can be determined that the tunnel meets the requirements during initial service, and only routine maintenance of the tunnel lining is required.

[0073] <Example 2>

[0074] During tunnel service, it is difficult to obtain data on the changes in surrounding rock pressure of the secondary lining. This second embodiment employs the method of the present invention to consider the lining displacement increment caused by changes in surrounding rock pressure. The initial displacement, displacement increment, and final displacement of the lining node in both directions are as follows: Figure 12 and 13 As shown. The initial displacement of the tunnel was determined by the calculated surrounding rock pressure under the initial service conditions of the tunnel, and the displacement increment of the tunnel was determined by comparing the results of cross-section scanning.

[0075] According to the method of this invention, a new numerical model is established, and the total nodal displacement is applied to the corresponding nodes of the numerical model. Simultaneously, constraints are applied, and numerical calculations are performed. Figure 14 As shown.

[0076] The calculated bending moment diagram and axial force diagram of the element are as follows: Figure 15 and 16 As shown, combining the function functions of the ultimate limit state and serviceability limit state of the concrete rectangular section bearing capacity, the safety factor distribution and crack width distribution of the lining unit are obtained as follows: Figure 17 and 18 As shown.

[0077] The tunnel's safety factor under this service condition is 2.09, and the crack width is 0.223 mm, both of which do not meet the requirements of railway tunnel specifications, indicating that the tunnel lining needs reinforcement. Comparison of the safety factor, crack width, and other condition indicators obtained by the method of this invention with the actual measured conditions of the tunnel shows that the results are consistent, further confirming that it is feasible to use the method of this invention to obtain condition indicators for evaluating the service condition of a tunnel when the surrounding rock pressure cannot be obtained.

[0078] In this second embodiment, the specific reinforcement measures are as follows: For local tunnel cracks with a width of less than 0.5mm, if there is no water seepage, their impact on the safety and stability of the tunnel is relatively small. A surface sealing method can be used to reinforce the tunnel. This involves cleaning both sides of the crack with a wire brush, and then directly applying a mixture of epoxy mortar, early-strength cement mortar, and crystalline permeable materials in a specific ratio. If water seepage occurs in the crack, it is necessary to first stop the water seepage before applying the sealant to repair the crack.

[0079] <Example 3>

[0080] This embodiment three provides a method and apparatus for evaluating the service status of tunnel lining based on deformation response, which can automatically implement the above-mentioned method of the present invention. The apparatus includes a model construction unit, an equivalent nodal force determination unit, a surrounding rock pressure determination unit, a distribution determination unit, an input display unit, and a control unit.

[0081] The displacement increment determination unit performs the steps described in step 1 above to determine the displacement increment u2 of the tunnel from the time it was put into operation until a certain tunnel maintenance time t when the tunnel is in service.

[0082] The model building department performs the steps described in step 2 above to establish a load structure model of the tunnel.

[0083] The displacement application calculation unit performs the steps described in step 3 above. On the load structure model, it does not calculate and apply the increment or total amount of surrounding rock pressure, but directly applies displacement based on displacement increment u2, applies fixed constraints to all element nodes, and calculates the internal forces of the structure.

[0084] The parameter acquisition section performs the steps described in step 4 above, and obtains the safety factor and crack width of the element based on the structural internal forces of the element.

[0085] The evaluation department performs the steps described in step 5 above to evaluate the tunnel's service status at tunnel maintenance time t based on the safety factor and crack width.

[0086] The reinforcement measures generation department obtains the service status assessment results of the tunnel lining and information on whether water seepage occurs in the tunnel cracks in actual engineering, and generates a corresponding reinforcement plan for the corresponding location of the tunnel based on this information.

[0087] The input display unit is used to allow users to input operation commands and displays the corresponding information. For example, the input display unit can display the displacement increment u2 determined by the displacement increment determination unit, the load structure model established by the model construction unit, and the process and data of applying the displacement increment u2 to calculate the internal forces of the structure by the displacement application calculation unit, displayed statically or dynamically at the corresponding position of the model. It can also display the safety factor and crack width of the elements obtained by the parameter acquisition unit and the evaluation results of the service status obtained by the evaluation unit at the corresponding position of the model. Furthermore, it can correlate and display the reinforcement scheme generated by the reinforcement measure generation unit with the service status evaluation results and information on whether water seepage occurs in the tunnel cracks in actual engineering at the corresponding position of the tunnel.

[0088] The control unit is communicatively connected to the displacement increment determination unit, model construction unit, displacement application calculation unit, parameter acquisition unit, evaluation unit, reinforcement measure generation unit, and input display unit, and controls their operation.

[0089] The above embodiments are merely illustrative examples of the technical solutions of the present invention. The method and apparatus for assessing the service status of tunnel lining based on deformation response involved in the present invention are not limited to the contents described in the above embodiments, but are defined by the scope of the claims. Any modifications, additions, or equivalent substitutions made by those skilled in the art based on these embodiments are within the scope of protection claimed by the claims of the present invention.

Claims

1. A method for assessing the service state of a tunnel lining based on the deformation response, characterized in that, The method comprises the following steps: Step 1, determine the displacement increment of the tunnel in service state, from the time of putting into operation to the time t of tunnel maintenance ; Step 2, establishing a load structure model of the tunnel; Step 3, on the load structure model, without calculating and applying the surrounding rock pressure increment or total amount, but based on the displacement increment The total displacement of the tunnel The fixed constraint is directly applied to each node of the tunnel structure, and then the internal force of the structure is directly calculated by ANSYS software; Step 4, obtaining the safety factor and crack width of the unit according to the structural internal force of the unit; Step 5, evaluating the service state of the tunnel at the tunnel maintenance time t according to the safety factor and crack width; wherein, represents the displacement of the tunnel when the lining structure reaches the equilibrium state under the combined action of the self-weight of the lining and the surrounding rock pressure; In step 1, the cross-section shape data of the tunnel at the time of putting into operation and the cross-section shape data of the tunnel at the time t of maintenance are acquired by using a three-dimensional laser scanner, and then the displacement increment is determined ; In step 5, the calculated safety factor and crack width are compared with the limit state threshold, and then the service state of the tunnel lining is evaluated; on this basis, combined with whether the tunnel cracks appear water seepage in the actual engineering, corresponding reinforcement measures are formulated to ensure that the tunnel can be operated safely for a long time.

2. The tunnel lining service state evaluation method based on deformation response according to claim 1, characterized in that: wherein In step 2, the ANSYS software is used to establish a load structure model of the tunnel.

3. Apparatus for assessing the service state of a tunnel lining on the basis of a deformation response, characterized by It comprises: The displacement increment determining unit determines the displacement increment of the tunnel from the time when the tunnel is put into operation to the time t when the tunnel is maintained in the service state ; A model construction unit for establishing a load structure model of the tunnel; The displacement application calculation unit, on the load structure model, does not calculate and apply the surrounding rock pressure increment or total amount, but is based on the displacement increment The total displacement of the tunnel The direct application to each node of the tunnel structure is fixedly constrained to all element nodes, and then the internal force of the structure is directly calculated by the ANSYS software. A parameter obtaining unit for obtaining the safety factor and crack width of the unit according to the structural internal force of the unit; An evaluation unit for evaluating the service state of the tunnel at the tunnel maintenance time t according to the safety factor and crack width; A control unit in communication with the displacement increment determination unit, the model construction unit, the displacement application calculation unit, the parameter obtaining unit and the evaluation unit, for controlling the operation of them; A reinforcement measure generation unit in communication with the control unit, for obtaining the service state evaluation result of the tunnel lining and information about whether the tunnel cracks appear water seepage in the actual engineering, and generating a corresponding reinforcement scheme for the corresponding position of the tunnel according to the information; wherein, represents the displacement of the tunnel when the lining structure is deformed and reaches an equilibrium state under the combined action of the self-weight of the lining and the pressure of the surrounding rock. The displacement increment determining part obtains the cross section shape data of the tunnel when the tunnel is put into operation and the cross section shape data of the tunnel at the moment t of maintenance, and then determines the displacement increment .

4. The deformation response based tunnel lining serviceability assessment apparatus according to claim 3, wherein, It further comprises: An input display unit in communication with the displacement increment determination unit, the model construction unit, the displacement application calculation unit, the parameter obtaining unit, the evaluation unit, the reinforcement measure generation unit and the control unit, for letting the user input operation instructions and performing corresponding display.

5. The tunnel lining service state evaluation device based on deformation response according to claim 4, characterized in that: wherein The input display part can display the displacement increment determined by the displacement increment determination part according to the operation instruction The load structure model established by the model construction part is displayed, and the displacement increment is applied to the displacement application calculation part The process and data of calculating the internal force of the structure are statically or dynamically displayed at the corresponding positions of the model, the safety factor and the crack width of the unit obtained by the parameter obtaining part and the evaluation result of the service state by the evaluation part are displayed at the corresponding positions of the model, and the reinforcement scheme generated by the reinforcement measure generation part is associated with the service state evaluation result and the information of whether the tunnel cracks appear to seep water in the actual engineering at the corresponding positions of the tunnel.

6. The tunnel lining service state evaluation device based on deformation response according to claim 4, characterized in that: wherein The model construction unit is to establish a load structure model of the tunnel by using the ANSYS software.

Images