A method for predicting shield machine cutterhead jam during construction

Abstract

This invention proposes a method for predicting machine jamming during tunnel boring machine (TBM) cutterhead construction. Specifically, it is a method for determining whether a TBM will jam when encountering a boulder in front of its cutterhead. First, relevant data is acquired, and it is calculated whether the horizontal projection of the boulder is entirely inside the TBM cutterhead. Based on two scenarios—whether the horizontal projection of the boulder is entirely inside the TBM cutterhead or not entirely—corresponding judgment procedures are set. This method has the advantages of strong process flow, simple structure, and reliable results.

Description

Technical Field

[0001] This invention relates to the field of infrastructure construction, and in particular to a method for predicting machine jamming during tunnel boring machine (TBM) cutterhead construction. Background Technology

[0002] Tunnel boring machines (TBMs) are a common type of equipment used in subway tunnel construction. They are popular due to their fast construction speed and high safety. However, in areas with weathered residual granite soil, isolated boulders may be present, posing a significant challenge to TBM construction. If the boulder is large, or if the TBM's torque is insufficient, the cutterhead may become stuck and unable to rotate, necessitating a work stoppage to deal with the boulder. Currently, there is no reliable method to determine whether the cutterhead will be stuck by an isolated boulder in front. Summary of the Invention

[0003] The main objective of this invention is to overcome the aforementioned defects in the prior art and to propose a method for determining whether a tunnel boring machine (TBM) is stuck when it encounters a boulder in front of its cutterhead. This method has the advantages of being streamlined, simple in structure, and reliable in results.

[0004] The present invention adopts the following technical solutions:

[0005] A method for predicting cutterhead jamming during tunnel boring machine (TBM) construction includes:

[0006] (1) Obtain the design maximum torque M of the tunnel boring machine cutterhead. max 1. Cutter head diameter D;

[0007] (2) Obtain the undrained shear strength c of the soil in front of the cutterhead. u ;

[0008] (3) Obtain the cohesion c and internal friction angle of the soil in front of the cutterhead. and severe gamma;

[0009] (4) Calculate the residual torque M of the cutterhead cutting the soil. L ;

[0010]

[0011] (5) Obtain the position (x0, y0) of the center of the boulder in the cutterhead coordinate system;

[0012] (6) Obtain the diameter d of the boulder using geophysical exploration methods;

[0013] (7) If the horizontal projection of the boulder is entirely inside the cutterhead of the tunnel boring machine, i.e. When this happens, the following procedure is used for determination:

[0014] (7-1) Determine the remaining thrust p of the tunnel boring machine cutterhead acting on the boulder;

[0015]

[0016] (7-2) Determine the resistance p' that the boulder can move in the soil;

[0017] p' = 1.2cN c +0.3γDN γ

[0018] in,

[0019]

[0020] (7-3) If p≥p', the tunnel boring machine cutterhead will not be jammed by a boulder; otherwise, if p<p', it will be jammed.

[0021] (8) If the horizontal projection of the boulder is not entirely inside the cutterhead of the tunnel boring machine, i.e. When this happens, the following procedure is used for determination:

[0022] (8-1) Determine the rotational force F exerted by the tunnel boring machine cutterhead on the boulder;

[0023]

[0024] (8-2) Determine the resistance F' to the rotation of the boulder;

[0025] F'=πc u d 2

[0026] (8-3) If F≥F', the tunnel boring machine cutterhead will not be jammed by a boulder; otherwise, if F<F', it will be jammed.

[0027] Specifically, the step of obtaining the undrained shear strength c of the soil in front of the cutterhead... u Specifically:

[0028] The undrained shear strength c of the exposed soil was determined using a vane shear test. u .

[0029] Specifically, the cohesion c and internal friction angle of the soil in front of the cutterhead are obtained. And severe γ, specifically:

[0030] Typical undisturbed soil samples were taken from the soil using a drilling rig and transported back to the laboratory for direct shear tests to determine the cohesion (c) and internal friction angle. Its density was determined by testing with a ring cutter, and then multiplied by the gravitational acceleration to obtain its specific weight γ.

[0031] Specifically, to obtain the position (x0, y0) of the center of the boulder in the cutterhead coordinate system, the following steps are taken:

[0032] With the center of the cutterhead as the origin of the coordinate system, the horizontal direction as the x-axis, and the vertical direction as the y-axis, a rectangular coordinate system is established. Based on the combination of geophysical exploration and drilling methods, the position (x0, y0) of the center of the boulder in the coordinate system is determined.

[0033] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention proposes a method for predicting machine jamming during tunnel boring machine (TBM) cutterhead construction. Specifically, it is a method for determining whether a TBM will jam when encountering a boulder in front of its cutterhead. First, relevant data is acquired, and it is calculated whether the horizontal projection of the boulder is entirely inside the TBM cutterhead. Based on two scenarios—whether the horizontal projection of the boulder is entirely inside the TBM cutterhead or not entirely—corresponding judgment procedures are set. This method has the advantages of strong process flow, simple structure, and reliable results. Attached Figure Description

[0035] Figure 1 A flowchart illustrating a method for determining whether a tunnel boring machine (TBM) is stuck when it encounters a boulder in front of its cutterhead, as provided in an embodiment of the present invention.

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0037] The working principle of this invention is that when the shield tunneling machine's cutterhead encounters a boulder, it generates a rotational jacking force on the boulder. If the horizontal projection of the boulder is inside the cutterhead, this jacking force must exceed the boulder's resistance to movement in the soil for the cutterhead to avoid jamming; otherwise, the cutterhead will jam. If the horizontal projection of the boulder is not entirely inside the shield tunneling machine's cutterhead, the rotational jacking force must exceed the boulder's resistance to rotation in the soil for the cutterhead to avoid jamming; otherwise, the cutterhead will jam. This principle is used to determine whether the cutterhead is jamming.

[0038] like Figure 1 The flowchart below shows the technical solution adopted in this invention, which specifically includes:

[0039] (1) Determine the maximum design torque M of the tunnel boring machine cutterhead. max , Cutter head diameter D.

[0040] Based on the design scheme of the tunnel boring machine, its maximum design torque M was determined. max , Cutter head diameter D.

[0041] (2) Determine the undrained shear strength c of the soil in front of the cutterhead. u .

[0042] The undrained shear strength c of the exposed soil was determined using a vane shear test. u .

[0043] (3) Determine the cohesion c and internal friction angle of the soil in front of the cutterhead. And severe γ.

[0044] Typical undisturbed soil samples were taken from the soil using a drilling rig and transported back to the laboratory for direct shear tests to determine the cohesion (c) and internal friction angle. Its density was determined by testing with a ring cutter, and then multiplied by the gravitational acceleration to obtain its specific weight γ.

[0045] (4) Determine the residual torque M of the cutterhead cutting the soil. L .

[0046]

[0047] (5) Determine the position (x0, y0) of the center of the boulder in the cutterhead coordinate system.

[0048] With the center of the cutterhead as the origin of the coordinate system, the horizontal direction as the x-axis, and the vertical direction as the y-axis, a rectangular coordinate system is established. Based on the combination of geophysical exploration and drilling methods, the position (x0, y0) of the center of the boulder in the coordinate system is determined.

[0049] (6) Determine the diameter d of the boulder.

[0050] The diameter d of the boulder was determined using geophysical methods.

[0051] (7) If the horizontal projection of the boulder is entirely inside the cutterhead of the tunnel boring machine, i.e. When this happens, the following procedure is used for determination:

[0052] (7-1) Determine the remaining thrust p of the shield machine cutterhead acting on the boulder.

[0053]

[0054] (7-2) Determine the resistance p' that the boulder can move in the soil.

[0055] p' = 1.2cN c +0.3γDN γ

[0056] in,

[0057]

[0058] (7-3) If p≥p', the tunnel boring machine cutterhead will not be jammed by a boulder; otherwise, if p<p', it will be jammed.

[0059] (8) If the horizontal projection of the boulder is not entirely inside the cutterhead of the tunnel boring machine, i.e. When this happens, the following procedure is used for determination:

[0060] (8-1) Determine the rotational force F of the shield machine cutterhead acting on the boulder.

[0061]

[0062] (8-2) Determine the resistance F' to the rotation of the boulder.

[0063] F'=πc u d 2

[0064] (8-3) If F≥F', the tunnel boring machine cutterhead will not be jammed by a boulder; otherwise, if F<F', it will be jammed.

[0065] Specific examples:

[0066] A subway tunnel in a Chinese city was being constructed using a tunnel boring machine (TBM). During the initial geological survey, isolated boulders were discovered in the strata. To determine whether the TBM cutterhead would be jammed by these boulders, the method described in this invention was employed. Based on the TBM design scheme, the maximum design torque M of the TBM cutterhead was determined. max The shear strength is 4500 kN·m, and the cutterhead diameter D is 6.0 m. The undrained shear strength c of the soil in front of the cutterhead is determined using a vane shear test. u The stress was 53.7 kPa. A typical undisturbed soil sample was taken from the soil using a drilling rig and transported back to the laboratory for direct shear testing. The cohesion c of the soil in front of the cutterhead was measured to be 35.7 kPa, and the internal friction angle was [missing value]. The angle is 23.5°; its density was measured using the ring cutter method, and then multiplied by the gravitational acceleration to obtain its specific weight γ, which is 19.2 kN / m³. 3 Determine the residual torque M of the cutterhead cutting the soil. L The value is 1464.9 kN·m. A rectangular coordinate system is established with the cutterhead center as the origin, the horizontal direction as the x-axis, and the vertical direction as the y-axis. Using a combination of geophysical exploration and drilling methods, the position of the center of boulder 1 in the cutterhead coordinate system is determined to be (x0, y0) (1.42 m, 1.13 m). The diameter d of the boulder is determined to be 0.76 m using geophysical methods. It is further confirmed that the entire horizontal projection of boulder 1 lies inside the tunnel boring machine (TBM) cutterhead. The remaining thrust p exerted by the TBM cutterhead on boulder 1 is determined to be 1785.0 kPa. The resistance p' that allows boulder 1 to move within the soil is determined to be 1103.5 kPa. Since p > p', the TBM cutterhead will not be jammed by boulder 1.

[0067] As the tunnel boring machine (TBM) continues its advance, it encounters boulder 2. The center of boulder 2 is located at (x0, y0) (2.26m, 1.93m) in the cutterhead coordinate system. Using geophysical methods, the diameter d of the boulder is determined to be 1.36m. Further investigation reveals that the horizontal projection of boulder 2 is not entirely within the TBM cutterhead. The rotational force F exerted by the cutterhead on the boulder is determined to be 493.2kN. The resistance force F' to the boulder's rotation is determined to be 311.9kN. Since F ≥ F', the TBM cutterhead will not be jammed by boulder 2.

[0068] This invention proposes a method for determining whether a tunnel boring machine (TBM) is stuck when it encounters a boulder in front of its cutterhead. First, relevant data is acquired, and it is calculated whether the horizontal projection of the boulder is entirely inside the cutterhead. Based on the two scenarios of whether the horizontal projection of the boulder is entirely inside the cutterhead or not, corresponding judgment procedures are set for each scenario. This method has the advantages of strong process flow, simple structure, and reliable results.

[0069] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A method for predicting machine jamming during tunnel boring machine (TBM) cutterhead construction, characterized in that, include: (1) Obtain the design maximum torque M of the tunnel boring machine cutterhead. max 1. Cutter head diameter D; (2) Obtain the undrained shear strength c of the soil in front of the cutterhead. u ; (3) Obtain the cohesion c and internal friction angle of the soil in front of the cutterhead. and severe gamma; (4) Calculate the residual torque M of the cutterhead cutting the soil. L ; (5) Obtain the position (x0, y0) of the center of the boulder in the cutterhead coordinate system; (6) Obtain the diameter d of the boulder using geophysical exploration methods; (7) If the horizontal projection of the boulder is entirely inside the cutterhead of the tunnel boring machine, i.e. When this happens, the following procedure is used for determination: (7-1) Determine the remaining thrust p of the tunnel boring machine cutterhead acting on the boulder; (7-2) Determine the resistance p' that the boulder can move in the soil; p'=1.2cN c +0.3γDN γ in, (7-3) If p≥p', the tunnel boring machine cutterhead will not be jammed by a boulder; otherwise, if p<p', it will be jammed. (8) If the horizontal projection of the boulder is not entirely inside the cutterhead of the tunnel boring machine, i.e. When this happens, the following procedure is used for determination: (8-1) Determine the rotational force F exerted by the tunnel boring machine cutterhead on the boulder; (8-2) Determine the resistance force F' to the rotation of the boulder; F'=πc u d 2 (8-3) If F≥F', the tunnel boring machine cutterhead will not be jammed by a boulder; otherwise, if F<F', it will be jammed.

2. The method for predicting tunnel boring machine cutterhead jamming according to claim 1, characterized in that, The undrained shear strength c of the soil in front of the cutterhead is obtained. u Specifically: The undrained shear strength c of the exposed soil was determined using a vane shear test. u .

3. The method for predicting cutterhead jamming during tunnel boring machine construction according to claim 1, characterized in that, Obtain the cohesion c and internal friction angle of the soil in front of the cutterhead. And severe γ, specifically: Typical undisturbed soil samples were taken from the soil using a drilling rig and transported back to the laboratory for direct shear tests to determine the cohesion (c) and internal friction angle. Its density was determined by testing with a ring cutter, and then multiplied by the gravitational acceleration to obtain its specific weight γ.

4. The method for predicting tunnel boring machine cutterhead jamming according to claim 1, characterized in that, To obtain the position (x0, y0) of the center of the boulder in the cutterhead coordinate system, specifically: With the center of the cutterhead as the origin of the coordinate system, the horizontal direction as the x-axis, and the vertical direction as the y-axis, a rectangular coordinate system is established. Based on the combination of geophysical exploration and drilling methods, the position (x0, y0) of the center of the boulder in the coordinate system is determined.

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