Evaluation methods based on analysis of shield tunneling construction.

Abstract

This invention discloses an analysis and evaluation method for shield tunneling construction, relating to the field of engineering construction. The method includes: selecting the soil, rock, and structures within the shield tunneling node area; simplifying the model; establishing the model, wherein a three-dimensional finite element model is established using Plaxis3D, with fully fixed constraints applied to the bottom of the geometric model, vertical sliding constraints applied to both sides, and the model surface as a free boundary; and simulating the soil using a hardened soil model; and analyzing and evaluating the calculation results. This method, through analysis and evaluation of shield tunneling construction, sets reasonable construction control parameters and controllable protection indicators for shield tunneling. It also provides reliable advance prediction and judgment for construction control of risk factors during shield tunneling, effectively controlling and adjusting the shield tunneling construction to prevent ground settlement and improve the tunneling accuracy and quality.

Description

[0001] This application is a divisional application of patent application No. 202010142122.X, filed on March 6, 2020, entitled "Analysis and Evaluation Method for Shield Tunneling Construction". Technical Field

[0002] This invention relates to the field of engineering construction technology, and in particular to an analysis and evaluation method for shield tunneling construction. Background Technology

[0003] The shield tunneling method is a construction method that uses a shield tunneling machine for tunnel excavation and other operations. It involves using a shield to excavate tunnels through soft foundations or fractured rock strata. However, during the shield tunneling process, the surrounding environment, existing tunnels, subway lines, building foundations, and underground pipelines may experience uncontrollable ground subsidence due to the new tunnel's tunneling, leading to safety risks and other hazards. Therefore, it is evident that the tunneling of a new shield tunnel impacts existing tunnels and may even disrupt their normal operation. Thus, effective analysis and evaluation of new shield tunneling construction is of significant practical importance. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide an analysis and evaluation method for shield tunneling construction. This method can analyze and evaluate the shield tunneling construction to set reasonable construction control parameters and controllable protection indicators. It can then provide reliable advance prediction and judgment of risk factors during shield tunneling construction, effectively control and adjust the shield tunneling construction, prevent ground subsidence, improve the tunneling accuracy and quality, and thus avoid risks such as deformation of existing and newly built tunnels, thereby increasing the safety factor of the construction.

[0005] To achieve the above objectives, according to one aspect of the present invention, an analysis and evaluation method for shield tunneling construction is provided, characterized by comprising: selecting the soil, rock, and structures within the shield tunneling node range; simplifying the model; establishing the model, wherein a three-dimensional finite element model is established using Plaxis3D, the bottom of the geometric model is subject to fully fixed constraints, the sides are subject to vertical sliding constraints, the model surface is a free boundary, and the soil is simulated using a soil hardening model; and analyzing and evaluating the calculation results.

[0006] Optionally, the simplified model may also include: simplifying the positional relationship between the new tunnel and the existing tunnel; and simplifying the geological strata.

[0007] Optionally, simplifying the positional relationship between the new tunnel and the existing tunnel includes: establishing calculation models for the left and right lines of the new tunnel respectively, wherein the center-to-center distance between the left and right lines of the new tunnel is 40m and exists before and after the shield tunneling construction, wherein the slope of the new tunnel is 0, the burial depth is taken at the highest point, and wherein the new tunnel and the existing tunnel at the shield tunneling node are simplified to a straight line.

[0008] Optionally, the formation simplification includes: filtering out the intermediate layer and retaining only the 2-2, 4N-2, 7-3, and 9-3 formations; and supplementing the cohesion parameters of 2-2, wherein the compressive modulus of 9-3 is 150,000 and the lateral pressure coefficient is 0.3.

[0009] Optionally, in the newly established model, the formation loss rate is set to 0.6%, and the construction process simulation is carried out step by step according to the actual construction sequence.

[0010] Optionally, the construction process simulation is divided into five calculation cases in sequence: the new tunnel approaches the existing tunnel; the new tunnel excavation face reaches the boundary of the existing tunnel; the new tunnel excavation face reaches the bottom of the existing tunnel; the new tunnel excavation face reaches the other side boundary of the existing tunnel; and the new tunnel reaches the model boundary.

[0011] Optionally, the total length of the three-dimensional finite element model is 100m, the total width is 100m, and the depth is 40m.

[0012] Optionally, the analysis and evaluation of the calculation results include: for the new tunnel's left or right shield tunnel passing under an existing tunnel, different cross sections are selected, and the settlement patterns of the existing and new tunnels are obtained through data extraction lines from different cross sections.

[0013] Optionally, when the shield tunneling machine of the new tunnel passes under an existing tunnel on the left or right line: the settlement of the existing tunnel is longitudinal along the excavation line, and the closer the shield tunneling face of the new tunnel is to the existing tunnel, the greater the impact on the existing tunnel; the settlement of the new tunnel gradually develops, and at the intersection of the new tunnel and the existing tunnel, the surface settlement above the new tunnel decreases; and the maximum surface settlement of the new tunnel is greater than that of the existing tunnel, and the ratio of the maximum surface settlement of the existing tunnel to that of the new tunnel is within a first numerical range.

[0014] Optionally, for the construction of the left tunnel of the new tunnel, the ratio of the maximum surface settlement of the existing tunnel to the new tunnel is a first ratio, while for the construction of the right tunnel of the new tunnel, the ratio of the maximum surface settlement of the existing tunnel to the new tunnel is a second ratio, and the values ​​of the first ratio and the second ratio are within a first value range.

[0015] One embodiment of the above invention has the following advantages or beneficial effects: the method can analyze and evaluate the shield tunneling construction, thereby setting reasonable construction control parameters and controllable protection indicators for shield tunneling, and thus providing reliable advance prediction and judgment for construction control of risk factors in shield tunneling construction. It can effectively control and adjust the shield tunneling construction, prevent ground subsidence, avoid risks such as deformation of existing and newly built tunnels, improve the safety factor of construction, and improve the tunneling accuracy and quality of shield construction.

[0016] The further effects of the aforementioned unconventional alternative methods will be explained below in conjunction with specific implementation methods. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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 effort. In the drawings:

[0018] Figure 1 This is a schematic diagram of the main process of the analysis and evaluation method for shield tunneling construction according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic plan view of the shield tunneling section according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the calculated cross-section of the left tunnel of a newly constructed tunnel according to an embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the calculated cross-section of the right tunnel of a newly constructed tunnel according to an embodiment of the present invention.

[0022] Figure 5 This is a schematic diagram of the calculation model of the left tunnel of a newly built tunnel and the tunnel's positional relationship according to an embodiment of the present invention.

[0023] Figure 6 This is a schematic diagram of the calculation model of the right tunnel of a newly built tunnel and the tunnel's positional relationship according to an embodiment of the present invention.

[0024] Figure 7 This is a schematic diagram of the calculation conditions for finite element construction process simulation according to an embodiment of the present invention.

[0025] Figure 8 This is a schematic diagram of the cross-section of the calculated results of the left tunnel of the newly constructed tunnel according to an embodiment of the present invention.

[0026] Figure 9This is a schematic diagram of the settlement curve of an existing tunnel when the left-line shield tunnel of a newly built tunnel passes under an existing tunnel according to an embodiment of the present invention.

[0027] Figure 10 This is a schematic diagram of the settlement curve of the newly constructed tunnel when the left-line shield tunnel passes under an existing tunnel according to an embodiment of the present invention.

[0028] Figure 11 This is a schematic diagram of the cross-section of the calculated results of the right tunnel of the newly constructed tunnel according to an embodiment of the present invention.

[0029] Figure 12 This is a schematic diagram of the settlement curve of an existing tunnel when the right-line shield tunnel of a newly constructed tunnel passes under an existing tunnel according to an embodiment of the present invention.

[0030] Figure 13 This is a schematic diagram of the settlement curve of the newly constructed tunnel when the right-line shield tunnel passes under an existing tunnel according to an embodiment of the present invention. Detailed Implementation

[0031] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0032] According to one aspect of the embodiments of the present invention, the present invention is based on Figures 1 to 13 An analysis and evaluation method for shield tunneling construction is provided.

[0033] Figure 1 This is a schematic diagram of the main process of the analysis and evaluation method for shield tunneling construction according to an embodiment of the present invention.

[0034] like Figure 1 As shown, the analysis and evaluation method for shield tunneling construction of the present invention mainly includes the following four steps: Step S1, selecting the soil, rock, and structures within the shield tunneling node area; Step S2, simplifying the model; Step S3, establishing the model, wherein a three-dimensional finite element model is established using Plaxis3D, with fully fixed constraints applied to the bottom of the geometric model, vertical sliding constraints applied to both sides, and the model surface being a free boundary, and the soil is simulated using a soil hardening model; and Step S4, analyzing and evaluating the calculation results. Through engineering analogy, numerical simulation, analytical methods, and other calculation analyses, reasonable control and protection indicators and reasonable construction parameters are formulated to ensure the safety and reliability of the existing line, while also ensuring that settlement, uplift convergence, and horizontal displacement of the existing line caused by tunnel construction are controlled within the range allowed by environmental conditions.

[0035] Below, through Figures 2 to 13 The various method steps of the present invention will be described in detail below.

[0036] Figure 2 This is a schematic plan view of the shield tunneling section according to an embodiment of the present invention. Figure 2 As shown, the left and right tunnels of the new tunnel will be constructed by shield tunneling under the existing tunnels, with a sequential construction order. Furthermore, the left tunnel will pass under the existing tunnel at an angle of approximately 34°, while the right tunnel will pass under it at an angle of approximately 19°.

[0037] The embodiments of this invention employ a three-dimensional finite element numerical calculation method to analyze the impact of a newly constructed tunnel shield tunneling under an existing tunnel on the existing tunnel. In step S1 of this invention, the soil, rock, and structures within the shield tunneling node range are selected. For example, the geological conditions of the construction project corresponding to this invention are as follows: the right-line shield tunneling under the overlapping section's exit line tunnel passes through strata mainly consisting of marine-continental transitional facies (silty) fine sand, stiff plastic silty clay layer, and strongly weathered siltstone; the upper part of the tunnel is lake water and marine-continental transitional facies (silty) fine sand; and the left-line tunneling under the overlapping section's exit line tunnel mainly traverses marine-continental transitional facies (silty) fine sand, stiff plastic silty clay layer, and completely weathered siltstone, with the upper part of the tunnel consisting of artificial fill layer and marine-continental transitional facies (silty) fine sand.

[0038] In step S2 of the invention, the model is simplified. For example, simplifying the model includes: simplifying the positional relationship between the new tunnel and the existing tunnel; and simplifying the geological strata.

[0039] First, to simplify the positional relationship between the new tunnel and the existing tunnel, calculation models are established for the left and right lines of the new tunnel. The center-to-center distance between the left and right lines of the new tunnel is 40m, and this exists before and after the shield tunneling construction. The slope of the new tunnel is assumed to be 0, and the burial depth is taken as the highest point. At the shield tunneling node, the new tunnel and the existing tunnel are simplified as straight lines. Specifically, regarding the simplification of the positional relationship between the new and existing tunnels, the center-to-center distance between the left and right lines of the new tunnel is approximately 40m, and the construction of the left and right lines of the new tunnel proceeds sequentially, resulting in a construction sequence. However, this calculation does not consider the mutual influence between the two, and calculation models are established for the left and right lines separately. Considering the construction range of the new tunnel and the principle that the closer the tunnel is to the existing tunnel, the greater the danger, and the fact that the shield machine is constantly excavating downhill, the new tunnel is considered to have a 0-slope slope, and the burial depth is taken as the highest point, resulting in more conservative calculation results. At the shield tunneling node, the new tunnel can be considered as a straight line, while the existing tunnel has a certain curvature. However, considering the small modeling range, the existing tunnel is also simplified as a straight line.

[0040] On the other hand, in addition to simplifying the positional relationship between new and existing tunnels, it is also necessary to simplify the geological strata. Figure 3This is a schematic diagram of the calculated cross-section of the left tunnel of a newly constructed tunnel according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the calculated cross-section of the right tunnel of a newly constructed tunnel according to an embodiment of the present invention. Figure 3 and Figure 4 The calculated cross-sections of the newly constructed left and right tunnels correspond to the simplified strata in the steps. Specifically, the simplified strata include, for example, filtering out intermediate layers and retaining only strata 2-2, 4N-2, 7-3, and 9-3; and supplementing the cohesion parameter of 2-2, considering the compression modulus of 9-3 as 150,000, and the lateral pressure coefficient as 0.3. This is because the actual soil layers have poor interlayering and stratification; considering the most unfavorable working conditions, some intermediate layers were filtered out, for example, only retaining strata 2-2, 4N-2, 7-3, and 9-3. In addition, due to the lack of some stratum parameters, the cohesion parameter of 2-2 was supplemented based on experience, and the compression modulus of 9-3 was considered to be 150,000, and the lateral pressure coefficient was considered to be 0.3. For example, based on the geological survey report, the strata under construction are mostly fine sand with very few cohesive particles; therefore, the cohesion parameter of 2-2 is considered to be 0.

[0041] In step S3 of the invention, a model is established, wherein a three-dimensional finite element model is established using Plaxis3D, a fully fixed constraint is applied to the bottom of the geometric model, vertical sliding constraints are applied to both sides, the model surface is a free boundary, and the soil is simulated using a soil hardening model. Figure 5 This is a schematic diagram of the calculation model of the left tunnel of a newly built tunnel and the tunnel's positional relationship according to an embodiment of the present invention. Figure 6 This is a schematic diagram of the calculation model of the right tunnel of a newly built tunnel and the tunnel's positional relationship according to an embodiment of the present invention.

[0042] Specifically, for example, a three-dimensional finite element model is built using Plaxis3D, with a total length of 100m, a total width of 100m, and a depth of 40m. For example, a fully fixed constraint is applied to the bottom of the geometric model, and vertical sliding constraints are applied to both sides, with the model surface being a free boundary. For example, the soil is simulated using a soil hardening model, and the soil layer calculation parameters are determined by combining the geological survey report of this project with relevant engineering experience.

[0043] In step S3 of this embodiment of the invention, the formation loss rate is 0.6%, and the construction process simulation is carried out step by step according to the actual construction sequence.

[0044] Specifically, regarding the value of the ground loss rate, during shield tunnel construction, because the outer diameter of the shield casing is larger than the outer diameter of the tunnel segments, and there are issues with untimely and insufficient synchronous grouting at the shield tail, soil accumulates radially towards the tunnel segments, causing ground deformation and surface settlement, which is the so-called ground loss. In this calculation, the ground loss rate is considered to be 0.6%. This ground loss rate is a relatively general control level based on experience in earth pressure balance shield tunneling in soft soil strata. However, the weathered rock section corresponding to the construction using this invention has better strata characteristics than the empirically considered soft soil strata. Therefore, considering the overall construction control level, and not considering unconventional conditions such as occasional poor control of shield attitude or sudden changes in strata at the shield tunneling face, a ground loss rate of 0.6% is considered a relatively safe and conservative approach for this construction site.

[0045] For the work conditions, the construction process simulation in Plaxis3D finite element software follows the actual construction sequence step by step. For example, ... Figure 7 The diagram illustrates a finite element simulation of the construction process, divided into five calculation cases, using the right tunnel of a newly constructed tunnel as an example. Specifically, this simulation is divided into the following five calculation cases:

[0046] Condition 1: The new tunnel is close to the existing tunnel;

[0047] Condition 2: The excavation face of the new tunnel reaches the boundary of the existing tunnel;

[0048] Condition 3: The excavation face of the new tunnel reaches the bottom of the existing tunnel;

[0049] Condition 4: The excavation face of the new tunnel reaches the boundary on the other side of the existing tunnel; and

[0050] Condition 5: The newly built tunnel reaches the model boundary.

[0051] Next, in step S4 of this embodiment of the invention, the calculation results are analyzed and evaluated.

[0052] Specifically, when a new tunnel's left or right line shield tunnel passes under an existing tunnel, different cross-sections can be selected, and data extraction lines from these cross-sections can be used to obtain the settlement patterns of both the existing and new tunnels. For example, by selecting a first cross-section and a second cross-section, the data extraction lines from these two sections can represent the arch bottom curves of the existing and new tunnels, respectively, thus allowing the acquisition of the settlement patterns at the bottom of the existing tunnel and the surface settlement patterns at the top of the new tunnel. Specifically, for a new tunnel's left line shield tunnel passing under an existing tunnel, selecting a first and a second cross-section, where the data extraction line from the first cross-section represents the arch bottom axis of the existing tunnel, yields the surface settlement pattern of the existing tunnel, and the data extraction line from the second cross-section represents the arch bottom axis of the new tunnel, yielding the surface settlement pattern of the new tunnel. Similarly, for a new tunnel's right line shield tunnel passing under an existing tunnel, selecting a first and a second cross-section, where the data extraction line from the first cross-section represents the arch bottom axis of the existing tunnel, yields the surface settlement pattern of the existing tunnel, and the data extraction line from the second cross-section represents the arch bottom axis of the new tunnel, yielding the surface settlement pattern of the new tunnel.

[0053] By analyzing and comparing the settlement patterns of existing and newly constructed tunnels, this invention assesses whether the surface settlement of the tunnel is within a reasonable and permissible range, thereby setting reasonable construction control parameters and controllable protection indicators for shield tunneling. Through such preliminary assessment, this invention can effectively control and adjust shield tunneling construction, prevent problems such as ground settlement, avoid risks such as deformation of existing and newly constructed tunnels, improve the safety factor of construction, and enhance the tunneling accuracy and quality of shield tunneling.

[0054] Now combine Figures 8 to 13 The following is a detailed explanation of the calculation results analysis of the embodiments of the present invention. Figure 8 This is a schematic diagram of the cross-section of the calculated results of the left tunnel of the newly constructed tunnel according to an embodiment of the present invention. Figure 9 This is a schematic diagram of the settlement curve of an existing tunnel when the left-line shield tunnel of a newly built tunnel passes under an existing tunnel according to an embodiment of the present invention. Figure 10 This is a schematic diagram of the settlement curve of the newly constructed tunnel when the left-line shield tunnel passes under an existing tunnel according to an embodiment of the present invention. Figure 11 This is a schematic diagram of the cross-section of the calculated results of the right tunnel of the newly constructed tunnel according to an embodiment of the present invention. Figure 12 This is a schematic diagram of the settlement curve of an existing tunnel when the right-line shield tunnel of a newly constructed tunnel passes under an existing tunnel according to an embodiment of the present invention. Figure 13 This is a schematic diagram of the settlement curve of the newly constructed tunnel when the right-line shield tunnel passes under an existing tunnel according to an embodiment of the present invention.

[0055] First, from Figures 8 to 13The results show that when the new tunnel's left or right shield tunnel passes under an existing tunnel, the existing tunnel experiences longitudinal settlement along the excavation line. The closer the new tunnel's shield tunneling face is to the existing tunnel, the greater the impact on the existing tunnel. For example, the deformation of the existing tunnel is most significant when the new tunnel's shield tunneling face reaches the bottom of the existing tunnel or the other boundary of the existing tunnel.

[0056] Moreover, when the shield tunneling of the new tunnel passes under the existing tunnel on the left or right line, the settlement of the new tunnel gradually develops. Furthermore, at the intersection of the new tunnel and the existing tunnel, the surface settlement above the new tunnel is slightly reduced, indicating that the existence of the existing tunnel is conducive to reducing the development of surface settlement of the new tunnel.

[0057] Furthermore, when the left or right tunnel of a newly constructed tunnel passes under an existing tunnel, the maximum surface settlement of the newly constructed tunnel is greater than that of the existing tunnel, and the ratio of the maximum surface settlement of the existing tunnel to that of the newly constructed tunnel falls within a first numerical range. For example, the first numerical range is 0.4-0.6.

[0058] Specifically, after the new tunnel boring machine (TBM) passes under the existing tunnel, for the left-line TBM passing under the existing tunnel, the ratio of the maximum surface settlement of the existing tunnel to that of the new tunnel is a first ratio, for example, 7:16. For the right-line TBM passing under the existing tunnel, the ratio of the maximum surface settlement of the existing tunnel to that of the new tunnel is a second ratio, for example, 3.1:6. The values ​​of the first and second ratios are within the first numerical range.

[0059] Furthermore, the ratio of the maximum surface settlement of the existing tunnel during the construction of the new left tunnel to the maximum surface settlement of the existing tunnel during the construction of the new right tunnel is a third ratio, for example, a ratio of 7:6.2. And the ratio of the maximum surface settlement of the new tunnel during the construction of the new left tunnel to the maximum surface settlement of the new right tunnel is a fourth ratio, for example, a ratio of 4:3.

[0060] Specifically, for a newly constructed tunnel where the left-line shield tunnel passes under an existing tunnel, for example... Figure 8 As shown, the first section AA* and the second section BB* are selected as the analysis sections for the calculation results of the left line of the newly constructed tunnel. The data extraction line of the first section AA* is the arch bottom axis of the existing tunnel when the shield tunnel of the left line of the newly constructed tunnel passes under the existing tunnel. This allows us to obtain the settlement pattern of the bottom of the existing tunnel when the shield tunnel of the left line of the newly constructed tunnel passes under the existing tunnel (e.g., ...). Figure 9 As shown). The data extraction line of the second section BB* is the arch bottom axis of the new tunnel when the left-line shield tunnel passes under the existing tunnel. This allows us to obtain the surface settlement pattern at the top of the new tunnel when the left-line shield tunnel passes under the existing tunnel (e.g., Figure 10 (As shown).

[0061] Specifically, in Figure 9 In the middle, press on Figure 9 Excavation is carried out longitudinally, from bottom to top, in stages 1, 2, 3, 4, and 5. Here... Figure 9 Excavation 1, excavation 2, excavation 3, excavation 4, and excavation 5 can be respectively associated with the five working conditions 1, 2, 3, 4, and 5 mentioned above. Figure 9 The settlement curves of the five existing tunnels shown correspond to excavation 1, excavation 2, excavation 3, excavation 4, and excavation 5 respectively in the longitudinal direction from top to bottom.

[0062] from Figure 9 It can be concluded that when the new tunnel's left-line shield tunnel passes under an existing tunnel, as excavation progresses (e.g., excavation 1 to excavation 5), the settlement curve of the existing tunnel along the longitudinal direction of the excavation line gradually develops. The deformation is most significant in stages 3 (e.g., when the new tunnel shield tunneling face reaches the bottom of the existing tunnel) and 4 (e.g., when the new tunnel shield tunneling face reaches the other boundary of the existing tunnel). That is, the closer the excavation face is to the existing tunnel, the greater the impact on the existing tunnel, and this should be carefully considered during construction. Through such predictive analysis and evaluation, this invention can help to more accurately set the construction control parameters for the new tunnel shield tunneling, thereby reducing the risk of shield tunneling construction and improving the tunneling accuracy and quality. Furthermore, for example, after the new tunnel shield tunneling is completed, the maximum surface settlement of the existing tunnel bottom when the new tunnel's left-line shield tunneling under the existing tunnel is approximately 7 mm.

[0063] Furthermore, in Figure 10 In the middle, the excavation faces 1 to 5 of the left line of the newly built tunnel are set according to... Figure 10 The horizontal direction is arranged from left to right. Figure 10 It can be seen that, Figure 10 The settlement curves of the surface subsidence above the five newly built tunnels shown in the figure are in... Figure 10 The horizontal directions, from left to right, correspond to excavation 1, excavation 2, excavation 3, excavation 4, and excavation 5, respectively. For example... Figure 10 As shown, with the excavation of the left tunnel of the new section, surface subsidence directly above the new tunnel gradually develops. The location of the excavation face is where the subsidence is greatest. For example, after the excavation of the new tunnel is completed, the maximum surface subsidence above the new tunnel can reach 16mm. It is worth noting that at the intersection of the left tunnel of the new tunnel and the existing tunnel, the surface subsidence above the new tunnel decreases slightly, indicating that the presence of the existing tunnel helps to reduce the development of surface subsidence of the new tunnel.

[0064] It can be seen that, for the new tunnel's left-line shield tunnel passing under the existing tunnel, the ratio of the maximum surface settlement of the existing tunnel to the new tunnel is the first ratio, for example, the first ratio is 7:16. The first ratio is within the first numerical range (for example, 0.4-0.6).

[0065] For example, if the right-side tunnel passes under an existing tunnel... Figure 11 As shown, similar to the left-line tunnel passing under the existing tunnel, the first section AA* and the second section BB* are selected as the analysis sections of the calculation results for the right line of the newly built tunnel section.

[0066] The data extraction line of the first section AA* is the axis of the arch bottom of the existing tunnel when the right-line shield tunnel of the new tunnel passes under the existing tunnel. This allows us to obtain the settlement pattern of the bottom of the existing tunnel when the right-line shield tunnel of the new tunnel passes under the existing tunnel (e.g., Figure 12 As shown). The data extraction line of the second section BB* is the arch bottom axis of the new tunnel when the right-line shield tunnel passes under the existing tunnel. This allows us to obtain the surface settlement pattern at the top of the new tunnel when the right-line shield tunnel passes under the existing tunnel (e.g., Figure 13 (As shown).

[0067] Specifically, in Figure 11 In the middle, press on Figure 11 The excavation is carried out longitudinally from bottom to top as follows: excavation 1, excavation 2, excavation 3, excavation 4, and excavation 5. For example, Figure 11 Excavation 1, excavation 2, excavation 3, excavation 4, and excavation 5 can be respectively associated with the five working conditions 1, 2, 3, 4, and 5 mentioned above. Figure 11 The settlement curves of the five existing tunnels shown correspond to excavation 1, excavation 2, excavation 3, excavation 4, and excavation 5 respectively in the longitudinal direction from top to bottom.

[0068] from Figure 11 It can be concluded that when the right-line tunnel of the newly constructed section passes under the exit line of the existing tunnel, the settlement curve of the existing tunnel along the longitudinal direction of the excavation line gradually develops as excavation progresses. The deformation is most significant in stages 3 (e.g., when the shield tunneling face of the new tunnel reaches the bottom of the existing tunnel) and 4 (e.g., when the shield tunneling face of the new tunnel reaches the other boundary of the existing tunnel). That is, the closer the excavation face is to the existing tunnel, the greater the impact on the existing tunnel, and this should be carefully considered during construction. Through such predictive analysis and evaluation, this invention can help to more accurately set the construction control parameters for the shield tunneling of the new tunnel, thereby reducing the risk of shield tunneling construction and improving the tunneling accuracy and quality. Furthermore, for example, after the shield tunneling of the new tunnel is completed, the maximum surface settlement of the bottom of the existing tunnel when the right-line shield tunneling of the new tunnel passes under the existing tunnel is approximately 6.2 mm.

[0069] Furthermore, in Figure 12 In the middle, the excavation faces 1 to 5 of the right line of the newly built tunnel are set according to... Figure 12 The horizontal direction is arranged from left to right. Figure 12 It can be concluded that Figure 12 The settlement curves of the ground surface subsidence directly above the five newly built tunnels shown in the figure are... Figure 12 The horizontal directions, from left to right, correspond to excavation 1, excavation 2, excavation 3, excavation 4, and excavation 5, respectively. For example... Figure 12 As shown, with the excavation of the right tunnel of the new section, surface subsidence directly above the new tunnel gradually develops. The location of the excavation face is where the subsidence is greatest. For example, after the excavation of the new tunnel is completed, the maximum surface subsidence above the new tunnel can reach 12mm. Similarly, at the intersection of the right tunnel of the new tunnel and the existing tunnel, the surface subsidence above the new tunnel is slightly reduced, indicating that the existence of the existing tunnel helps to reduce the development of surface subsidence of the new tunnel.

[0070] It can be seen that the new tunnel's right-line shield tunnel passes under the existing tunnel, and the ratio of the maximum surface settlement of the existing tunnel to the new tunnel is the second ratio, for example, 3.1:6. The second ratio is within the range of the first value (for example, 0.4-0.6).

[0071] Regardless of whether the new tunnel is under construction on the left or right line, the maximum surface settlement of the new tunnel is greater than that of the existing tunnel. This point should be taken into account when setting construction parameters to ensure reasonable parameter settings.

[0072] Based on the calculation results of the construction of the left and right tunnels mentioned above, the ratio of the maximum surface settlement of the existing tunnel during the construction of the left tunnel to that during the construction of the right tunnel is the third ratio, for example, 7:6.2. Furthermore, the ratio of the maximum surface settlement of the newly constructed tunnel during the construction of the left tunnel to that during the construction of the right tunnel is the fourth ratio, for example, 4:3. The third and fourth ratios are approximately the same and within the allowable range. The sequential construction of the left and right tunnels does not cause significant errors in the surface settlement of either the existing or newly constructed tunnels. The construction parameters can be finely adjusted to account for this characteristic.

[0073] By pre-evaluating the calculation results obtained above, construction parameters can also be collected in advance to avoid risks such as disturbance to existing tunnels caused by unstable or unreasonable construction parameters, as well as other construction risks caused by related measurement and equipment problems.

[0074] From another perspective, during the construction of the left tunnel of the new tunnel, the maximum difference in surface settlement between the existing tunnel (or the newly built tunnel) and during the construction of the right tunnel of the new tunnel is within a controllable and reasonable range, and the difference in maximum surface settlement between the existing tunnel and the newly built tunnel during the construction of either the left or right tunnel of the new tunnel is also within a controllable and reasonable range. The specific details are as follows.

[0075] The difference between the maximum surface settlement of the existing tunnel during the construction of the left tunnel and the maximum surface settlement of the existing tunnel during the construction of the right tunnel is defined as a first value, which falls within the range of a second value. For example, if the maximum surface settlement of the existing tunnel is 7 mm during the construction of the left tunnel and 6.2 mm during the construction of the right tunnel, the difference between these two values ​​is only 0.8 mm. In other words, for the existing tunnel, the error in the maximum surface settlement between the left and right tunnels during the construction of the new tunnel is within the second value range (e.g., within 1 mm).

[0076] Furthermore, the difference between the maximum surface settlement of the newly constructed tunnel during the construction of the left tunnel and the maximum surface settlement of the newly constructed tunnel during the construction of the right tunnel is the second value, which falls within the range of the third value. For example, if the maximum surface settlement of the newly constructed tunnel is 16mm during the construction of the left tunnel, and 12mm during the construction of the right tunnel, the difference between the two values ​​is the second difference, which is 4mm. In other words, for newly constructed tunnels, the error in the maximum surface settlement between the construction of the left and right tunnels is within the range of the third value (e.g., within 4mm).

[0077] Furthermore, for example, the difference between the first difference and the second difference is 3.2 mm.

[0078] To address this error, the evaluation and analysis method of this invention allows for adjustments to the tunneling parameters of the shield tunneling project based on the obtained calculation results. This enables the setting of reasonable construction parameters and control and protection indicators, thereby ensuring the safety and reliability of existing or newly constructed tunnels under both left and right line construction scenarios. Even when the left and right lines of the new tunnel are constructed sequentially, the error in construction risk values ​​for both scenarios remains within a reasonable and controllable range.

[0079] On the other hand, as mentioned above, during the construction of the new left tunnel, the difference between the maximum surface settlement of the existing tunnel and the maximum surface settlement of the new tunnel is the third value, which falls within the fourth value range. For example,

[0080] During the construction of the new left tunnel, the maximum surface settlement of the existing tunnel was 7 mm, while the maximum surface settlement of the new tunnel was 16 mm. The difference between the two values ​​is the third difference, which is 9 mm. In other words, during the construction of the new left tunnel, the error between the maximum surface settlement of the existing tunnel and the maximum surface settlement of the new tunnel is within the fourth value range (e.g., within 9 mm).

[0081] For the construction of the right tunnel of a new tunnel, the difference between the maximum surface settlement of the existing tunnel and the maximum surface settlement of the new tunnel is considered the fourth value, which falls within the fifth value range. For example, if the maximum surface settlement of the existing tunnel is 6.2 mm and the maximum surface settlement of the new tunnel is 12 mm, then the difference between the two values ​​is the fourth value, which is 5.8 mm. In other words, during the construction of the right tunnel of a new tunnel, the error between the maximum surface settlement of the existing tunnel and the maximum surface settlement of the new tunnel is within the fifth value range (e.g., within 6 mm).

[0082] It can also be seen that for the construction of the left or right line of a new tunnel, the maximum surface settlement of the new tunnel is greater than that of the existing tunnel.

[0083] Furthermore, the difference between the third and fourth differences is 3.2 mm.

[0084] To address this error, the evaluation and analysis method of this invention allows for the setting of reasonable construction control parameters and controllable protection indicators for shield tunneling based on the obtained calculation results, ensuring that the deformation of both the newly built tunnel and the existing tunnel is within a reasonable and reliable range during the construction of the new tunnel.

[0085] The method described in this invention uses numerical simulation to analyze the impact of new tunnel excavation on existing tunnels, thereby establishing reasonable construction parameters and control and protection indicators. This keeps construction risks within acceptable limits, ensuring the safety, reliability, and normal operation of existing lines, while effectively controlling the construction risks of new tunnels and improving the excavation accuracy and quality of shield tunneling. This method also achieves true "dynamic design and dynamic construction."

[0086] In summary, the method of this invention can analyze and evaluate shield tunneling construction, thereby setting reasonable construction control parameters and controllable protection indicators for shield tunneling. This provides reliable advance prediction and judgment for construction control of risk factors in shield tunneling construction, enabling effective control and adjustment of shield tunneling construction, preventing ground settlement, avoiding risks such as deformation of existing and newly built tunnels, improving the safety factor of construction, and improving the tunneling accuracy and quality of shield construction.

[0087] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for evaluation by analyzing shield tunneling construction, characterized in that, include: Select the soil, rock, and structures within the shield tunneling node area; Simplified model; A model was established using Plaxis3D to create a three-dimensional finite element model. The bottom of the geometric model was subjected to fully fixed constraints, while vertical sliding constraints were applied to both sides. The model surface was a free boundary, and the soil was simulated using a hardened soil model. In this model, a new left tunnel and a new right tunnel were simultaneously constructed on both sides of the existing tunnel. The construction process simulation included the following five steps in sequence: the new tunnel approaching the existing tunnel; the new tunnel face reaching the boundary of the existing tunnel; the new tunnel face reaching the bottom of the existing tunnel; the new tunnel face reaching the other boundary of the existing tunnel; and the new tunnel reaching the model boundary; and... The analysis and evaluation results include assessing whether the surface settlement of the tunnel is within a reasonable and permissible range by analyzing and comparing the settlement patterns of existing and newly constructed tunnels. This allows for the setting of reasonable construction control parameters and controllable protection indicators for shield tunneling. The analysis and evaluation results include: for the left or right line of a newly constructed tunnel tunneling under an existing tunnel, different cross-sections are selected, and the settlement patterns of the existing and newly constructed tunnels are obtained through data extraction lines from different cross-sections. Regardless of whether the new tunnel is under construction on the left or right line, the maximum surface settlement of the new tunnel is greater than that of the existing tunnel. However, at the intersection of the new tunnel and the existing tunnel, the surface settlement above the new tunnel is slightly reduced, indicating that the existence of the existing tunnel is beneficial to reducing the development of surface settlement of the new tunnel.

2. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, The simplified model also includes: The positional relationship between the newly constructed tunnel and the existing tunnel is simplified, which includes: establishing calculation models for the left and right lines of the newly constructed tunnel, wherein the center-to-center distance between the left and right lines is 40m, and this exists before and after the shield tunneling construction; wherein the slope of the newly constructed tunnel is 0, the burial depth is taken as the highest point, and the newly constructed tunnel and the existing tunnel at the shield tunneling node are simplified to a straight line; and The simplified formation includes: filtering out the intermediate layer and retaining only the 2-2, 4N-2, 7-3, and 9-3 formations; and supplementing the cohesion parameters of 2-2, wherein the compressive modulus of 9-3 is 150,000 and the lateral pressure coefficient is 0.

3.

3. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, For the new tunnel's left-line shield tunneling under an existing tunnel, a first section and a second section are selected. The data extraction line of the first section is the arch bottom axis of the existing tunnel, thereby obtaining the settlement pattern of the existing tunnel's surface. Similarly, the data extraction line of the second section is the arch bottom axis of the new tunnel, thereby obtaining the settlement pattern of the new tunnel's surface.

4. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, For the right-line shield tunnel of the new tunnel passing under the existing tunnel, the first section and the second section are selected. The data extraction line of the first section is the arch bottom axis of the existing tunnel, so as to obtain the settlement law of the surface of the existing tunnel. The data extraction line of the second section is the arch bottom axis of the new tunnel, so as to obtain the settlement law of the surface of the new tunnel.

5. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, When a new tunnel's left or right shield tunnel passes under an existing tunnel: The existing tunnels all settled longitudinally along the excavation line. The deformation of the existing tunnels was most significant when the new tunnel shield tunnel reached the bottom of the existing tunnel after passing under the excavation face and when the new tunnel shield tunnel reached the other side boundary of the existing tunnel.

6. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, When constructing the left tunnel of the new tunnel, the ratio of the maximum surface settlement of the existing tunnel to the new tunnel is the first ratio, while when constructing the right tunnel of the new tunnel, the ratio of the maximum surface settlement of the existing tunnel to the new tunnel is the second ratio, and the values ​​of the first ratio and the second ratio are within the first value range.

7. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, When constructing the left tunnel of the new tunnel, the ratio of the maximum surface settlement of the existing tunnel to the maximum surface settlement of the existing tunnel when constructing the right tunnel of the new tunnel is the third ratio, and the ratio of the maximum surface settlement of the new tunnel when constructing the left tunnel to the maximum surface settlement of the new tunnel when constructing the right tunnel of the new tunnel is the fourth ratio, and the difference between the third ratio and the fourth ratio is within the allowable range.

8. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, When the left line of the new tunnel is under construction, the difference in maximum surface settlement between the existing tunnel or the new tunnel and when the right line of the new tunnel is under construction is within a controllable and reasonable range. Furthermore, when the left or right line of the new tunnel is under construction, the difference in maximum surface settlement between the existing tunnel and the new tunnel is also within a controllable and reasonable range.

9. The method for evaluation by analyzing shield tunneling construction according to claim 1, characterized in that, The difference between the maximum surface settlement of the existing tunnel during the construction of the new left tunnel and the maximum surface settlement of the existing tunnel during the construction of the new right tunnel is the first value, and the first value is within the range of the second value. The difference between the maximum surface settlement of the newly constructed tunnel during the construction of the left tunnel and the maximum surface settlement of the newly constructed tunnel during the construction of the right tunnel is the second value, and the second value is within the range of the third value. The difference between the maximum surface settlement of the existing tunnel and the maximum surface settlement of the new tunnel during the construction of the left tunnel is the third value, and the third value is within the range of the fourth value. as well as The difference between the maximum surface settlement of the existing tunnel and the maximum surface settlement of the new tunnel during the construction of the right tunnel is the fourth value, which is within the range of the fifth value.

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