Large-diameter shield underground butt joint stability judgment method

Abstract

The invention relates to the technical field of tunnel engineering construction, in particular to a large-diameter shield underground butt joint stability judgment method, which fully considers the seepage influence of an excavation face, and can more accurately calculate the ultimate support pressure of the excavation face of a shield tunnel compared with the existing method, thereby more accurately judging the underground butt joint stability of the large-diameter shield. In practical engineering application, construction accidents caused by stability judgment errors can be effectively reduced. Accurate stability information is provided for constructors, reinforcement measures such as support parameter adjustment and construction process optimization can be conveniently taken in time, safe butt joint construction in the shield is effectively guaranteed, and the accident occurrence probability is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering construction, and in particular to a method for judging the stability of underground butt joint of a large-diameter shield. Background Art

[0002] In modern underground space development and tunnel construction, tunnel diameters are getting larger and larger, and excavation distances are getting longer and longer. Large-diameter shield underground docking technology is becoming more and more widely used, such as the Shiziyang Tunnel and the Yongzhou Jintang Submarine Railway Tunnel in China. Large-diameter shields have become the main construction method due to their advantages such as high efficiency and safety. However, as a key link in shield construction, shield underground docking faces many technical challenges.

[0003] During the underground docking process of shield tunneling, the stability of the soil in the docking area is crucial. Once the soil is unstable, it may lead to serious consequences such as ground collapse, tunnel deformation and even shield machine damage. Existing technologies often have limitations when judging the stability of underground docking of large-diameter shield tunneling. Some traditional methods do not fully consider complex geological conditions, such as the differences in mechanical properties of different soil layers and the influence of groundwater.

[0004] The current large-diameter shield docking stability assessment has significant limitations: traditional theories are mostly based on the assumption of waterless conditions, ignoring the reconstruction effect of seepage force in high water pressure strata on the soil stress field; the existing calculation of underwater shield support pressure relies on numerical simulation and lacks a universal analytical model. Especially in submarine tunnel projects, the seepage effect caused by head difference will significantly reduce the stability of the excavation face, and the existing methods are difficult to quantify such dynamic effects, which can easily lead to deviations in support pressure design and increase construction risks. Summary of the invention

[0005] In order to overcome the shortcomings of the above technologies, the present invention provides a method for determining the stability of underground butt joints by coupling calculations of a multi-block dynamic model with seepage force, thereby solving the critical support pressure, reducing the risk of misjudgment of the support pressure, and improving the safety and reliability of underground butt joint construction of shield machines.

[0006] The technical solution adopted by the present invention to overcome the technical problems is: A method for judging the stability of underground butt joint of a large-diameter shield tunnel, comprising: (a) Construct a multi-cone failure model at the lower end of the formation; (b) Calculate the horizontal seepage force of the multi-cone failure model; (c) Calculate the power caused by gravity in the multi-cone failure model; (d) Calculate the power of the seepage force of the multi-cone failure model based on the horizontal seepage force of the multi-cone failure model; (e) Calculate the power loss of the multi-vertebral failure model; (f) The power of support pressure is calculated based on the power of gravity, seepage force and loss power of the multi-cone failure model. ; (g) Power according to support pressure Calculate the ultimate support pressure ; (h) According to the ultimate support pressure Determine whether the shield underground docking is in a stable state.

[0007] Furthermore, the multi-cone failure model in step (a) is composed of rigid blocks from top to bottom. , rigid block , rigid block The rigid block at the top is an isosceles triangle with the vertex at the top being , whose two vertices at the bottom are , , rigid block Edge With edge The vertex angle is , is the friction angle of soil, rigid block The bisector of the vertex angle is set in the vertical direction, and the rigid block Set on a rigid block The lower end of the triangle structure is a rigid block. The two upper vertices are , , whose lower vertex is , rigid block Set on a rigid block The lower end of the rigid block The two upper vertices are , , whose lower vertex is , rigid block Edge Set in the vertical direction, rigid block Edge Perpendicular to its side , the rigid block Vertex As the origin, a three-dimensional rectangular coordinate system is established, with the vertex With Vertex Rigid blocks The side length is equal to the diameter of the excavation face .

[0008] Furthermore, when the rigid block Height Greater than soil thickness When the rigid block From an isosceles triangle to an isosceles trapezoid, the upper vertices of the isosceles trapezoid are , .

[0009] Further, step (b) comprises the following steps: (b-1) By formula Calculate the rigid block Horizontal seepage force , where is the weight of water, , is the groundwater level, The water head of the shield sealed cabin pressure measuring tube. is the height of the tunnel excavation face, is the natural logarithm, To analyze the parameters of the approximation, Vertex The Y-axis coordinate value of (b-2) By formula Calculate the rigid block Horizontal seepage force , where Vertex The Z-axis coordinate value, Vertex The Y-axis coordinate value, Vertex The Y-axis coordinate value of (b-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculate the rigid block Horizontal seepage force , To analyze the parameters of the approximation, is the function's independent variable; (b-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculate the rigid block Horizontal seepage force .

[0010] Further, step (c) comprises the following steps: (c-1) By formula Calculate the rigid block The power of gravity , where is the soil layer thickness, A rigid block speed, is the height of the tunnel excavation face, is the friction angle within the soil; (c-2) By formula Calculate the rigid block The power of gravity , where A rigid block speed; (c-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculate the rigid block The power of gravity , where A rigid block speed; (c-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculate the rigid block The power of gravity .

[0011] Further, step (d) comprises the following steps: (d-1) by formula Calculate the rigid block The power produced by the seepage force ; (d-2) by formula Calculate the rigid block The power produced by the seepage force ; (d-3) by formula Calculate the rigid block The power produced by the seepage force .

[0012] Further, step (e) comprises the following steps: (e-1) by the formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss , where is the soil cohesion; (e-2) by formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss ; (e-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculated by vertex ,vertex With Vertex Composed of Power loss ; (e-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculated by vertex ,vertex With Vertex Composed of Power loss , where A rigid block Vertex With Vertex The length of the sides it forms; (e-5) by formula Calculated by vertex With Vertex The lines are parallel to the horizontal plane. Power loss , where A rigid block Relatively rigid block speed; (e-6) by formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss , where A rigid block Relatively rigid block speed.

[0013] Furthermore, in step (f), the formula Calculate the power generated by the support pressure .

[0014] Furthermore, in step (g), the formula Calculate the ultimate support pressure .

[0015] Further, step (h) comprises the following steps: (h-1) The actual support pressure of the tunnel is obtained by installing a pressure sensor or other monitoring equipment at the shield cutterhead. ; (h-2) When the actual support pressure Less than the ultimate support pressure When the shield is in the ground, it is determined that the butt joint is in a stable state; (h-3) When the actual support pressure Greater than or equal to the ultimate support pressure When the shield underground joint is determined to be in an unstable state.

[0016] The beneficial effects of the present invention are as follows: the present invention fully considers the influence of seepage on the excavation face, and compared with the existing methods, can more accurately calculate the ultimate support pressure of the shield tunnel excavation face, thereby more accurately judging the stability of the underground docking of large-diameter shields. In actual engineering applications, it can effectively reduce construction accidents caused by errors in stability judgment. Providing accurate stability information to construction personnel facilitates timely reinforcement measures, such as adjusting support parameters, optimizing construction processes, etc., effectively ensuring the safety of underground docking construction of shields and reducing the probability of accidents. The method is suitable for underground docking projects of large-diameter shields under different geological conditions and construction environments, has wide versatility, and can provide a reliable basis for stability judgment for various types of tunnel engineering construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a model in which the damage surface of the present invention does not reach the ground surface; Figure 2 A schematic diagram of a model in which the destruction surface of the present invention reaches the ground surface; Figure 3 It is a schematic diagram of the relative relationship of the movement speed of the slider of the present invention. DETAILED DESCRIPTION

[0018] The following is combined with Figure 1 , Attachment Figure 2 , Attachment Figure 3 The present invention is further described.

[0019] A method for judging the stability of underground butt joint of a large-diameter shield tunnel, comprising: (a) Construct a multi-cone failure model at the lower end of the formation.

[0020] (b) Calculation of the horizontal seepage force of the multi-cone failure model.

[0021] (c) Calculate the power caused by gravity in the multi-cone failure model.

[0022] (d) The power produced by the seepage force of the multi-cone failure model is calculated based on the horizontal seepage force of the multi-cone failure model.

[0023] (e) Calculate the power loss of the multi-vertebral failure model. The power loss of different surfaces is determined based on factors such as their area, internal friction angle of the ground and relative speed.

[0024] (f) The power of support pressure is calculated based on the power of gravity, seepage force and loss power of the multi-cone failure model. .

[0025] (g) Power according to support pressure Calculate the ultimate support pressure .

[0026] (h) According to the ultimate support pressure Determine whether the shield underground docking is in a stable state.

[0027] By constructing a multi-cone failure model and combining the shield construction excavation parameters and geological parameters in the shield tunnel project, the ultimate support pressure of the shield tunnel excavation is calculated. The ultimate support pressure By comparing it with the Zhihua pressure detected during tunnel excavation, it is used as one of the safety criteria for the tunnel excavation process.

[0028] As attached Figure 1 As shown, in one embodiment of the present invention, the multi-cone failure model in step (a) is composed of rigid blocks from top to bottom. , rigid block , rigid block The rigid block at the top is an isosceles triangle with the vertex at the top being , whose two vertices at the bottom are , ,vertex With Vertex The edges of the structure are set horizontally, and the rigid blocks Edge With edge The vertex angle is , is the friction angle of soil, rigid block The bisector of the vertex angle is set in the vertical direction, and the rigid block Set on a rigid block The lower end of the triangle structure is a rigid block. The two upper vertices are , , whose lower vertex is , rigid block Set on a rigid block The lower end of the rigid block The two upper vertices are , , whose lower vertex is , rigid block Edge Set in the vertical direction, rigid block Edge Perpendicular to its side ,side The angle with the horizontal direction is ,vertex With Vertex The edge With edge The angle is , the rigid block Vertex As the origin, a three-dimensional rectangular coordinate system is established, with the vertex With Vertex Rigid blocks The side length is equal to the diameter of the excavation face .

[0029] As attached Figure 2 As shown, in one embodiment of the present invention, when the rigid block Height Greater than soil thickness When the rigid block From an isosceles triangle to an isosceles trapezoid, the upper vertices of the isosceles trapezoid are , .

[0030] In one embodiment of the present invention, step (b) comprises the following steps: (b-1) By formula Calculate the rigid block Horizontal seepage force , where is the weight of water, , is the groundwater level, is the water head of the piezometer tube acting on the tunnel excavation surface (actually the water head of the piezometer tube in the shield sealed chamber). Here, the influence of the seepage force generated by the water head difference on the stress state and stability of the soil near the tunnel excavation surface when the shield machine is excavating underwater is considered. is the height of the tunnel excavation face, is the natural logarithm, The parameters of the analytical approximation are obtained by fitting the numerical results. Vertex The Y-axis coordinate value of .

[0031] (b-2) By formula Calculate the rigid block Horizontal seepage force , where Vertex The Z-axis coordinate value, Vertex The Y-axis coordinate value, Vertex The Y-axis coordinate value of .

[0032] (b-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculate the rigid block Horizontal seepage force , The parameters of the analytical approximation are obtained by fitting the numerical results. is the function's independent variable.

[0033] (b-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculate the rigid block Horizontal seepage force .

[0034] As attached Figure 3 As shown, in one embodiment of the present invention, step (c) comprises the following steps: (c-1) By formula Calculate the rigid block The power of gravity , where is the soil layer thickness, A rigid block speed, is the height of the tunnel excavation face, is the internal friction angle of soil.

[0035] (c-2) By formula Calculate the rigid block The power of gravity , where A rigid block speed.

[0036] (c-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculate the rigid block The power of gravity , where A rigid block speed.

[0037] (c-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculate the rigid block The power of gravity .

[0038] In one embodiment of the present invention, step (d) comprises the following steps: (d-1) by formula Calculate the rigid block The power produced by the seepage force .

[0039] (d-2) by formula Calculate the rigid block The power produced by the seepage force .

[0040] (d-3) by formula Calculate the rigid block The power produced by the seepage force .

[0041] In one embodiment of the present invention, step (e) comprises the following steps: (e-1) by the formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss , where It is the cohesion of soil.

[0042] (e-2) by formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss .

[0043] (e-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculated by vertex ,vertex With Vertex Composed of Power loss .

[0044] (e-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculated by vertex ,vertex With Vertex Composed of Power loss , where A rigid block Vertex With Vertex The length of the sides.

[0045] (e-5) by formula Calculated by vertex With Vertex The lines are parallel to the horizontal plane. Power loss , where A rigid block Relatively rigid block speed.

[0046] (e-6) by formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss , where A rigid block Relatively rigid block speed.

[0047] In one embodiment of the present invention, in step (f), the formula Calculate the power generated by the support pressure .

[0048] In one embodiment of the present invention, in step (g), the formula Calculate the ultimate support pressure .

[0049] In one embodiment of the present invention, step (h) comprises the following steps: (h-1) The actual support pressure of the tunnel is obtained by installing a pressure sensor or other monitoring equipment at the shield cutterhead. .

[0050] (h-2) When the actual support pressure Less than the ultimate support pressure At this time, it is determined that the shield underground connection is in a stable state and normal construction can continue.

[0051] (h-3) When the actual support pressure Greater than or equal to the ultimate support pressure When the shield ground connection is determined to be in an unstable state, an early warning signal can be issued to prompt the construction personnel to take processing measures, such as increasing the support pressure and adjusting the advancement speed. After taking measures, the ultimate support pressure is recalculated and compared with the actual support pressure to judge the stability of the ground connection again.

[0052] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining the stability of underground docking of a large-diameter shield, characterized in that: include: (a) Construct a multi-cone failure model at the lower end of the formation; (b) Calculate the horizontal seepage force of the multi-cone failure model; (c) Calculate the power caused by gravity in the multi-cone failure model; (d) Calculate the power of the seepage force of the multi-cone failure model based on the horizontal seepage force of the multi-cone failure model; (e) Calculate the power loss of the multi-vertebral failure model; (f) The power of support pressure is calculated based on the power of gravity, seepage force and loss power of the multi-cone failure model. ; (g) Power according to support pressure Calculate the ultimate support pressure ; (h) According to the ultimate support pressure Determine whether the shield underground docking is in a stable state.

2. The method for determining the stability of underground docking of a large-diameter shield according to claim 1 is characterized in that: In step (a), the multi-cone failure model consists of rigid blocks from top to bottom. , rigid block , rigid block The rigid block at the top is an isosceles triangle with the vertex at the top being , whose two vertices at the bottom are , , rigid block Edge With edge The vertex angle is , is the friction angle of soil, rigid block The bisector of the vertex angle is set in the vertical direction, and the rigid block Set on a rigid block The lower end of the triangle structure is a rigid block. The two upper vertices are , , whose lower vertex is , rigid block Set on a rigid block The lower end of the rigid block The two upper vertices are , , whose lower vertex is , rigid block Edge Set in the vertical direction, rigid block Edge Perpendicular to its side , the rigid block Vertex As the origin, a three-dimensional rectangular coordinate system is established, with the vertex With Vertex Rigid blocks The side length is equal to the diameter of the excavation face .

3. The method for determining the stability of underground docking of a large-diameter shield according to claim 2 is characterized in that: When the rigid block Height Greater than soil thickness When the rigid block From an isosceles triangle to an isosceles trapezoid, the upper vertices of the isosceles trapezoid are , .

4. The method for determining the stability of underground docking of a large-diameter shield according to claim 2 is characterized in that: Step (b) comprises the following steps: (b-1) By formula Calculate the rigid block Horizontal seepage force , where is the weight of water, , is the groundwater level, The water head of the shield sealed cabin pressure measuring tube. is the height of the tunnel excavation face, is the natural logarithm, To analyze the parameters of the approximation, Vertex The Y-axis coordinate value of (b-2) By formula Calculate the rigid block Horizontal seepage force , where Vertex The Z-axis coordinate value, Vertex The Y-axis coordinate value, Vertex The Y-axis coordinate value of (b-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculate the rigid block Horizontal seepage force , To analyze the parameters of the approximation, is the function's independent variable; (b-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculate the rigid block Horizontal seepage force .

5. The method for determining the stability of underground docking of a large-diameter shield according to claim 4 is characterized in that: Step (c) comprises the following steps: (c-1) By formula Calculate the rigid block The power of gravity , where is the soil layer thickness, A rigid block speed, is the height of the tunnel excavation face, is the friction angle within the soil; (c-2) By formula Calculate the rigid block The power of gravity , where A rigid block speed; (c-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculate the rigid block The power of gravity , where A rigid block speed; (c-4) When the failure surface reaches the ground surface, it is a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculate the rigid block The power of gravity .

6. The method for determining the stability of underground docking of a large-diameter shield according to claim 5 is characterized in that: Step (d) comprises the following steps: (d-1) by formula Calculate the rigid block The power produced by the seepage force ; (d-2) by formula Calculate the rigid block The power produced by the seepage force ; (d-3) by formula Calculate the rigid block The power produced by the seepage force .

7. The method for determining the stability of underground docking of a large-diameter shield according to claim 3 is characterized in that: Step (e) comprises the following steps: (e-1) by the formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss , where is the soil cohesion; (e-2) by formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss ; (e-3) When the failure surface does not reach the ground surface, it is a rigid block The vertical height Less than or equal to the thickness of the overburden When, through the formula Calculated by vertex ,vertex With Vertex Composed of Power loss ; (e-4) When the failure surface reaches the ground surface, it becomes a rigid block The vertical height Greater than the thickness of the overburden When, through the formula Calculated by vertex ,vertex With Vertex Composed of Power loss , where A rigid block Vertex With Vertex The length of the sides that form it; (e-5) by formula Calculated by vertex With Vertex The lines are parallel to the horizontal plane. Power loss , where A rigid block Relatively rigid block speed; (e-6) by formula Calculated by vertex With Vertex The lines are perpendicular to the horizontal plane. Power loss , where A rigid block Relatively rigid block speed.

8. The method for determining the stability of underground docking of a large-diameter shield according to claim 7 is characterized in that: In step (f), the formula Calculate the power generated by the support pressure .

9. The method for determining the stability of underground docking of a large-diameter shield according to claim 5, characterized in that: In step (g), the formula Calculate the ultimate support pressure .

10. The method for determining the stability of underground docking of a large-diameter shield according to claim 1, characterized in that: Step (h) comprises the following steps: (h-1) The actual support pressure of the tunnel is obtained by installing a pressure sensor or other monitoring equipment at the shield cutterhead. ; (h-2) When the actual support pressure Less than the ultimate support pressure When the shield is in the ground, it is determined that the butt joint is in a stable state; (h-3) When the actual support pressure Greater than or equal to the ultimate support pressure When the shield underground joint is determined to be in an unstable state.

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