Three-dimensional settlement prediction method induced by tunnel excavation

Abstract

The present invention discloses a method for predicting three-dimensional settlement induced by tunnel excavation, which comprises the following steps: S1. Construct a two-dimensional settlement function for a single tunnel according to the width of the ground soil settlement trough and the maximum ground settlement value; S2. Construct a three-dimensional settlement function for a single tunnel; S3. Respectively construct a three-dimensional settlement function for a double tunnel and a three-dimensional settlement function for a connection passage according to the three-dimensional settlement function of the single tunnel; S4. Calculate the settlement value induced by the excavation of the double tunnel according to the three-dimensional settlement function of the double tunnel; S5. Calculate the settlement value induced by the excavation of the connection passage according to the three-dimensional settlement function of the connection passage; S6. Add the settlement value induced by the excavation of the double tunnel and the settlement value induced by the excavation of the connection passage to obtain the settlement value of the double tunnel considering the connection passage in three-dimensional space. The present invention solves the problems that the existing tunnel excavation ground settlement prediction methods have low prediction accuracy and are all aimed at one-dimensional and two-dimensional working conditions, lacking a three-dimensional settlement prediction method.

Description

Technical Field

[0001] The present invention relates to the field of formation settlement prediction, and particularly to a three-dimensional settlement prediction method induced by tunnel excavation. Background Art

[0002] Tunnel excavation will destroy the initial equilibrium state of the soil mass, causing different degrees of settlement in the nearby formation. Excessive formation settlement will directly affect the structural stability of surrounding existing buildings and structures. Therefore, in actual engineering, it is necessary to reasonably predict the settlement values of the surface and deep soil mass after construction before the tunnel is excavated, so as to take corresponding control measures in advance to ensure the safety of the construction adjacent environment.

[0003] At present, regarding the prediction of formation settlement caused by tunnel excavation, there is mainly the numerical simulation method. According to the tunnel size and burial depth, a three-dimensional finite element model is established, and then displacement constraints are imposed on the soil mass. The disturbance of the tunneling machine to the soil mass is simulated by applying a forced displacement to the tunnel wall, including the influence of over-excavation gap, grouting pressure, etc. on the soil mass, and the settlement value is calculated therefrom. That is, the existing numerical simulation combines the excavation method and the support sequence, etc. to specifically simulate the tunnel excavation process, and the change characteristics of formation displacement can be intuitively obtained. However, since it is difficult for the model soil parameters and boundary conditions to be consistent with the actual situation, the prediction results often deviate greatly from the on-site monitoring data. Summary of the Invention

[0004] Aiming at the above deficiencies in the prior art, the three-dimensional settlement prediction method induced by tunnel excavation provided by the present invention solves the problems that the existing tunnel excavation formation settlement prediction methods have low prediction accuracy and are all for one-dimensional and two-dimensional working conditions, lacking a three-dimensional settlement prediction method.

[0005] In order to achieve the above invention purpose, the technical solution adopted by the present invention is: a three-dimensional settlement prediction method induced by tunnel excavation, including the following steps:

[0006] S1. Construct a single-tunnel two-dimensional settlement function according to the width of the surface soil settlement trough and the maximum surface settlement value;

[0007] S2. Construct a single-tunnel three-dimensional settlement function according to the single-tunnel two-dimensional settlement function and the longitudinal settlement function of the surface directly above the tunnel;

[0008] S3. Construct a double-tunnel three-dimensional settlement function and a connection passage three-dimensional settlement function respectively according to the single-tunnel three-dimensional settlement function;

[0009] S4. Calculate the settlement value induced by the excavation of the double-tunnel according to the double-tunnel three-dimensional settlement function;

[0010] S5. Calculate the settlement value induced by the excavation of the connection passage according to the connection passage three-dimensional settlement function;

[0011] S6. Add the settlement value induced by the excavation of the double - hole tunnel and the settlement value induced by the excavation of the connection passage to obtain the settlement value of the double - hole tunnel considering the connection passage in three - dimensional space.

[0012] Further, the single - hole two - dimensional settlement function in step S1 is:

[0013]

[0014] Among them, as Figure 2 shown, S(x, z) is the single - hole two - dimensional settlement function, S max is the maximum surface settlement value, x is the horizontal distance from the prediction point to the tunnel center, z is the depth of the prediction point, a is the parameter of different soil types, z 0 is the buried depth of the tunnel center, and i is the width of the surface soil settlement trough.

[0015] The beneficial effects of the above - mentioned scheme are as follows: The present invention introduces the depth position of the prediction point as a variable. While retaining the advantages of clear physical meaning, few parameters, effectiveness, and speed, it improves the generality of the formula, so that the application scope of the settlement prediction formula is not limited to surface settlement, and settlement prediction can also be made for deep soil layers.

[0016] Further, the surface longitudinal settlement function directly above the tunnel in step S2 is:

[0017] S(y) = S max {g(y - y s ) - g(y - y e )}

[0018]

[0019]

[0020] Among them, S(y) is the surface longitudinal settlement function directly above the tunnel, y is the longitudinal position of the tunnel, y s is the starting position of the tunnel in the longitudinal direction, y e is the ending position of the tunnel in the longitudinal direction, g(y - y s ) and g(y - y e ) are the first probability functions, k is the maximum slope of the surface longitudinal settlement, and η is the face displacement release rate.

[0021] Further, the single - hole three - dimensional settlement function in step S2 is:

[0022]

[0023] Among them, S d (x, y, z) is the single - hole three - dimensional settlement function.

[0024] The beneficial effects of this solution are as follows: Existing settlement prediction formulas can only reflect the lateral settlement trough when the instantaneous settlement of the soil mass is basically stable after tunnel excavation, and cannot calculate the longitudinal settlement of the soil mass caused thereby. The present invention introduces the longitudinal position of the prediction point as a variable, and considers the longitudinal settlement of the soil mass during the settlement prediction process, improving the prediction accuracy of the formula.

[0025] Further, the three-dimensional settlement function of the double tunnels in step S3 is as follows:

[0026]

[0027]

[0028]

[0029] Among them, S s (x, y, z) is the three-dimensional settlement function of the double tunnels, S max，l is the maximum surface settlement value when the left main tunnel exists alone, s max，r is the maximum surface settlement value when the right main tunnel exists alone, gξ(y - y s ) and gξ(y - y e ) are the second probability functions, ξ takes l or r, l represents the left main tunnel, r represents the left main tunnel, L is the distance between the centerlines of the left and right main tunnels, i l is the surface settlement trough width of the left main tunnel, i r is the surface settlement trough width of the right main tunnel.

[0030] The beneficial effects of this solution are as follows: Existing settlement prediction formulas are mostly limited to single-tunnel tunnels, while the application of double-tunnel tunnels is increasing in actual projects. The present invention extends the single-tunnel tunnel settlement prediction method to double-tunnel tunnels through coordinate transformation and linear superposition, providing a method for the settlement prediction of double-tunnel tunnels.

[0031] Further, the three-dimensional settlement function of the cross passage in step S3 is as follows:

[0032]

[0033]

[0034]

[0035] Among them, S h (x, y, z) is the three-dimensional settlement function of the cross passage, S max,h is the maximum surface settlement value when the cross passage exists alone, i h is the surface settlement trough width of the cross passage, k is the maximum slope of the surface longitudinal settlement, g h(x + 0.5L) and g h (x - 0.5L) is the third probability function.

[0036] The beneficial effects of the above further solution are as follows:

[0037] Applying the three-dimensional settlement prediction method of the main tunnel to the connecting passage, considering the settlement generated by the connecting passage in the total settlement, further improving the prediction accuracy.

[0038] In summary, the beneficial effects of the present invention are as follows: Based on the existing horizontal distance x, the longitudinal position y and depth z are introduced to calculate the settlement value of the double-hole tunnel considering the connecting passage from a three-dimensional perspective. During the settlement prediction process, the longitudinal settlement of the soil body and the settlement generated by the connecting passage are considered, improving the prediction accuracy of the formula. And the width i of the ground soil settlement trough is inversely deduced using the easily monitored ground surface settlement value, and then the difficult-to-monitor underground settlement value is predicted. The on-site monitoring data (the maximum slope k of the ground surface longitudinal settlement and the face displacement release rate η) of the excavated part of the tunnel are used to predict the ground surface and underground settlements of the unexcavated part ahead, realizing the prediction of the future settlement degree during excavation. Description of the Drawings

[0039] Figure 1 It is a flowchart of the three-dimensional settlement prediction method induced by tunnel excavation.

[0040] Figure 2 Schematic diagram of the ground soil settlement trough.

[0041] Figure 3 It is a schematic diagram of the model provided by the embodiment of the present invention.

[0042] Figure 4 It is a diagram of the predicted results of the formation settlement at different depths under different buried depths of the connecting passage provided by the embodiment of the present invention.

[0043] Figure 5 It is a diagram of the predicted results of the formation settlement at different transverse vertical planes under different buried depths of the connecting passage provided by the embodiment of the present invention.

[0044] Figure 6 It is a diagram of the predicted results of the formation settlement at different longitudinal vertical planes under different buried depths of the connecting passage provided by the embodiment of the present invention. Detailed Embodiments

[0045] The following describes the detailed embodiments of the present invention to facilitate those skilled in the art of the present technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the detailed embodiments. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0046] As shown Figure 1 in the figure, the three-dimensional settlement prediction method induced by tunnel excavation includes the following steps:

[0047] S1. According to the width of the ground soil settlement trough and the maximum ground settlement value, construct a single-tunnel two-dimensional settlement function;

[0048] The single-tunnel two-dimensional settlement function in step S1 is:

[0049]

[0050] where S(x, z) is the single-tunnel two-dimensional settlement function, S max is the maximum ground settlement value, x is the horizontal distance from the tunnel center, z is the depth of the prediction point, a is a parameter for different soil types, 0 is the tunnel center depth, and i is the width of the ground soil settlement trough.

[0051] In this embodiment, when the soil of the tunnel is clay, a = 0.65; when the soil of the tunnel is sand, a = 0.5; x is perpendicular to the excavation direction of the main tunnel of the tunnel.

[0052] S2. According to the single-tunnel two-dimensional settlement function and the longitudinal settlement function of the ground surface directly above the tunnel, construct a single-tunnel three-dimensional settlement function;

[0053] The longitudinal settlement function of the ground surface directly above the tunnel in step S2 is:

[0054] S(y) = S max {g(y - y s ) - g(y - y e )}

[0055]

[0056]

[0057] where S(y) is the longitudinal settlement function of the ground surface directly above the tunnel, y is the longitudinal position of the tunnel, y s is the starting position of the tunnel in the longitudinal direction, y e is the ending position of the tunnel in the longitudinal direction, g(y - y s ) and g(y - y e ) are the first probability functions, k is the maximum slope of the longitudinal settlement of the ground surface, η is the face displacement release rate, and S max is the maximum ground settlement value.

[0058] The single-tunnel three-dimensional settlement function in step S2 is:

[0059]

[0060] where Sd (x, y, z) is a single - hole three - dimensional settlement function.

[0061] In step S2, the specific process of obtaining the single - hole three - dimensional settlement function is as follows: according to the longitudinal settlement function of the ground surface directly above the tunnel, calculate the maximum settlement value of the ground surface corresponding to the longitudinal position y, and substitute the obtained maximum settlement value of the ground surface into the single - hole two - dimensional settlement function to obtain the single - hole three - dimensional settlement function.

[0062] In this embodiment, the y - direction is parallel to the tunnel excavation direction. The face displacement release rate η takes 20% in soft clay strata, 40% in hard clay and sandy strata; the maximum slope k of the longitudinal ground surface settlement takes 1 mm / m in soft soil strata, 2 mm / m in sandy strata, and 3 mm / m in hard clay strata.

[0063] When constructing the connection passage, the double - hole tunnel has been excavated. Therefore, it is considered that the excavation starting point and ending point of the double - hole tunnel are both at infinity, that is, y s =-∞, y e =∞.

[0064] S3. Construct the double - hole three - dimensional settlement function and the connection - passage three - dimensional settlement function respectively according to the single - hole three - dimensional settlement function;

[0065] In this embodiment, x, y, and z are physical quantities of the coordinate axes in three directions. Perform translation coordinate transformation and linear superposition on the single - hole three - dimensional settlement function to obtain the double - hole three - dimensional settlement function. Perform rotation coordinate transformation on the single - hole three - dimensional settlement function to obtain the connection - passage three - dimensional settlement function.

[0066] The double - hole three - dimensional settlement function in step S3 is:

[0067]

[0068]

[0069]

[0070] Among them, S s (x, y, z) is the double - hole three - dimensional settlement function, S max，l is the maximum settlement value of the ground surface when the left - hand main tunnel exists alone, S max，r is the maximum settlement value of the ground surface when the right - hand main tunnel exists alone, a is a parameter of different soil types, z is the depth of the prediction point, z 0 is the center depth of the tunnel, g ξ (y - y s ) and g ξ (y - y e ) are the second probability functions, ξ takes l or r, y s is the starting position of the tunnel in the longitudinal direction, ye is the end position in the longitudinal direction of the tunnel, x is the horizontal distance from the prediction point to the tunnel center, k is the maximum slope of the longitudinal surface settlement, η is the displacement release rate of the tunnel face, L is the spacing between the centerlines of the left and right main tunnels, and i l is the width of the surface settlement trough of the left main tunnel, and i r is the width of the surface settlement trough of the right main tunnel, and y is the longitudinal position of the tunnel.

[0071] When ξ takes l:

[0072]

[0073]

[0074] When ξ takes r:

[0075]

[0076]

[0077] In this embodiment, the starting point of the horizontal distance x from a point on the surface to the tunnel center is located on the central axis of the double - hole tunnel.

[0078] The three - dimensional settlement function of the connection tunnel in step S3 is:

[0079]

[0080]

[0081]

[0082] Among them, S h (x, y, z) is the three - dimensional settlement function of the connection tunnel, and S max，h is the maximum surface settlement value when the connection tunnel exists alone, and i h is the width of the surface settlement trough of the connection tunnel, k is the maximum slope of the longitudinal surface settlement, and g h (x + 0.5L) and g h (x - 0.5L) are the third probability functions.

[0083] S4. Calculate the settlement value induced by the excavation of the double - hole tunnel according to the double - hole three - dimensional settlement function;

[0084] The double - hole three - dimensional settlement function Ss ( x, y, z) is used to calculate the settlement value induced by the excavation of the double - hole tunnel.

[0085] S5. Calculate the settlement value induced by the excavation of the connection tunnel according to the three - dimensional settlement function of the connection tunnel;

[0086] The three - dimensional settlement function S of the connection tunnelh (x, y, z) calculates the settlement value induced by the excavation of the connecting passage. In this embodiment, the starting point and the ending point of the excavation of the connecting passage are the centerlines of the left and right line tunnels.

[0087] S6. Add the settlement value induced by the excavation of the double - hole tunnel and the settlement value induced by the excavation of the connecting passage to obtain the double - hole tunnel settlement value S of the three - dimensional connecting passage.

[0088] S = S s (x, y, z) + S h (x, y, z) In this embodiment, the excavation direction of the connecting passage is perpendicular to the double - hole tunnel. The direction of the horizontal distance x from a point on the ground surface to the tunnel center is the longitudinal direction of the connecting passage, and the direction of the longitudinal position y is the transverse direction of the connecting passage.

[0089] Figure 3 This is a schematic diagram of the double - hole tunnel model considering the connecting passage provided by the embodiment of the present invention. It can be seen from the figure that the zero point of the x - axis is located on the central axis of the double - hole tunnel. The excavation direction of the connecting passage is perpendicular to the double - hole tunnel. The x - direction represents the longitudinal direction of the connecting passage, and the y - direction represents the transverse direction of the connecting passage.

[0090] Using the method of the present invention to predict the soil settlement of the embodiment of the present invention, the experimental results are as Figure 4 、 Figure 5 、 Figure 6 shown, which are respectively the predicted results of the formation settlement at different depths under different buried depths of the connecting passage, the predicted results of the formation settlement at different transverse vertical planes under different buried depths of the connecting passage, and the predicted results of the formation settlement at different longitudinal vertical planes under different buried depths of the connecting passage.

[0091] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Three-dimensional settlement prediction method induced by tunnel excavation, Characterized in that: It includes the following steps: S1. Construct a single-tunnel two-dimensional settlement function according to the width of the ground soil settlement trough and the maximum ground settlement value; S2. Construct a single-tunnel three-dimensional settlement function according to the single-tunnel two-dimensional settlement function and the longitudinal ground settlement function directly above the tunnel; S3. Construct a double-tunnel three-dimensional settlement function and a connection passage three-dimensional settlement function respectively according to the single-tunnel three-dimensional settlement function; S4. Calculate the settlement value induced by the excavation of the double-tunnel according to the double-tunnel three-dimensional settlement function; S5. Calculate the settlement value induced by the excavation of the connection passage according to the connection passage three-dimensional settlement function; S6. Add the settlement value induced by the excavation of the double-tunnel and the settlement value induced by the excavation of the connection passage to obtain the settlement value of the double-tunnel considering the connection passage in the three-dimensional space; Among them, the order of steps S4 and S5 can be exchanged; The double-tunnel three-dimensional settlement function in step S3 is: Among them, S s (x, y, z) is the double - hole three - dimensional settlement function, S max，l is the maximum surface settlement value of the left - hand main tunnel when it exists alone, S max，r is the maximum surface settlement value of the right - hand main tunnel when it exists alone, g ξ (y - y s ) and g ξ (y - y e ) are the second probability functions, ξ takes l or r, L is the distance between the centerlines of the left - and right - hand main tunnels, i l is the width of the surface settlement trough of the left - hand main tunnel, i r is the width of the surface settlement trough of the right - hand main tunnel; The connection passage three-dimensional settlement function in step S3 is: Among them, S h (x, y, z) is the three-dimensional settlement function of the connection passage, and S max，h is the maximum ground settlement value when the connection passage exists alone. i h is the width of the ground settlement trough of the connection passage. g h (x + 0.5L) and g h (x - 0.5L) are the third probability functions. z is the horizontal distance from the tunnel center, z is the depth of the prediction point, a is the parameter of different soil types, z 0 is the tunnel center depth, i is the width of the ground soil settlement trough, y is the longitudinal position of the tunnel, y s is the starting position of the tunnel in the longitudinal direction, y e is the ending position of the tunnel in the longitudinal direction. k is the maximum slope of the ground longitudinal settlement, and η is the face displacement release rate.

2. The three-dimensional settlement prediction method induced by tunnel excavation according to claim 1, Characterized in that: The single-tunnel two-dimensional settlement function in step S1 is: Among them, S(x, z) is the single-hole two-dimensional settlement function, and S max is the maximum surface settlement value.

3. The three-dimensional settlement prediction method induced by tunnel excavation according to claim 2, Characterized in that: The longitudinal ground settlement function directly above the tunnel in step S2 is: S(y) = S max {g(y - y s ) - g(y - y e )} Among them, S(y) is the longitudinal settlement function of the ground surface directly above the tunnel, and g(y - y s ) and g(y - y e ) are the first probability functions.

4. The three-dimensional settlement prediction method induced by tunnel excavation according to claim 3, Characterized in that, The single-tunnel three-dimensional settlement function in step S2 is: Among them, S d (x, y, z) is a single-hole three-dimensional settlement function.

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