Prediction method for ground surface settlement caused by tunnel crossing goaf

Abstract

The invention relates to the technical field of tunnel safety monitoring, in particular to a method for predicting ground surface settlement caused by tunnel crossing goaf, which comprises the following steps of: determining mining thickness and rock attributes at a top plate; establishing a stratigraphic profile map; constructing a stratum loss rate function; a ground surface settlement prediction function is obtained according to the stratum loss rate function and a poeck formula, and the final ground surface settlement amount is obtained; by delimiting the range of a caving zone, a fissure zone and a bending zone above a goaf, the damage state of a rock mass to be traversed by a tunnel after the goaf is formed by coal mining is mastered, namely, a stratum profile map is obtained based on the damage state after first disturbance; and taking the stratum loss rate under the condition of rock mass secondary disturbance caused by tunnel excavation as a starting point, considering surrounding rock secondary disturbance, fitting the stratum loss rate of the whole bottom layer through a straight line on the basis of the function coordinate I and the function coordinate II, and optimizing and improving related parameters in a traditional check formula so as to accurately predict the ground surface settlement amount.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel safety monitoring, and in particular to a method for predicting surface subsidence caused by a tunnel passing through a goaf. Background Art

[0002] Coal mining will inevitably form goafs, which will disturb the overlying rock mass and destroy its integrity. The disturbed rock mass is looser and has worse integrity than the undisturbed rock mass. Tunnel lines are interconnected, and some tunnels will inevitably pass through the loose rock mass above the goaf, causing secondary disturbance of the rock mass. Since the rock mass above the goaf is looser and has poor stability, this poses a hidden danger to the excavation of the tunnel and the safety of the buildings above it.

[0003] Nowadays, the precise value of surface settlement caused by tunnel construction through goaf, a special geological condition, is mostly determined by experiments or simulations. The traditional Peck formula is widely used in a large number of surface settlement problems caused by tunnel construction because of its simple principle and convenient calculation. However, it is suitable for strata that have not been disturbed by mining, because the goaf formed by mining causes the strata to loosen, that is, the strata are already heterogeneous when the tunnel passes through. Therefore, the traditional Peck formula has certain limitations when applied to strata with goafs. As a result, when the traditional Peck formula is applied to the tunnel passing above the goaf, due to the fragmentation of the rock, the surface settlement prediction will produce huge errors, which is difficult to meet the accuracy requirements of the project. Summary of the invention

[0004] In order to solve the technical problem that the existing test method for determining the amount of surface settlement has large errors and poor accuracy, the purpose of the present invention is to provide a method for predicting surface settlement caused by a tunnel passing through a goaf, wherein the goaf includes a roof, and the technical scheme adopted is as follows:

[0005] Step 1: Determine the mining thickness and rock properties at the roof;

[0006] Step 2, establishing a stratigraphic profile of the caving zone, the fracture zone and the bending zone which are delineated in sequence along the axial direction based on the mining thickness and the rock properties near the goaf;

[0007] Step 3, determine the position of the neutral axis of the bending zone based on the stratigraphic profile, obtain the vertical distance between the neutral axis of the bending zone and the roof, calculate the stratum loss rate of the non-goaf area, and obtain the function coordinate 1 of the non-goaf area based on the vertical distance between the neutral axis of the bending zone and the roof and the stratum loss rate of the non-goaf area; obtain the rock expansion coefficient according to the rock properties, correct the stratum loss rate of the non-goaf area based on the expansion coefficient, and obtain the vertical distance between the neutral axis of the bending zone and the goaf, and the function coordinate 2 about the tunnel passing through the caving zone, fracture zone and bending zone on the goaf; perform linear fitting on the function coordinate 1 and the function coordinate 2 to construct the stratum loss rate function of the tunnel passing through the caving zone, fracture zone and bending zone on the goaf;

[0008] Step 4: According to the formation loss rate function and the Peck formula, the surface settlement prediction function is obtained to obtain the final surface settlement.

[0009] Preferably, the mining thickness is defined as h, the soil layer at the roof is 0h, and the rock properties include hard rock and soft rock. If the roof is hard rock, the caving zone is [0h, 5h], and the fracture zone is [5h, 13h]; if the roof is soft rock, the caving zone is [0h, 3h], and the fracture zone is [3h, 6h]; the bending zone is from one end of the fracture zone close to the surface to the surface.

[0010] Preferably, the function coordinate 1 is (V 0 ,y 中 ); the function coordinate 2 is (kV 0 ,0); the formation loss rate function is:

[0011]

[0012] Among them, V l represents the corrected formation loss rate; k represents the expansion coefficient; V 0 represents the stratum loss rate in the non-mined area; y 中 It represents the vertical distance between the neutral axis of the bending zone and the roof; h represents the mining thickness.

[0013] Preferably, step 4 includes: obtaining a corrected formation loss rate through a formation loss rate function, calculating the surface subsidence in combination with the Peck formula, superimposing it with the original subsidence data caused by mining, obtaining a surface subsidence prediction function across the goaf, and obtaining the final surface subsidence.

[0014] Preferably, the equipment used for the tunnel to pass through the goaf includes a shield machine and a settlement tank, and the surface settlement prediction function is:

[0015]

[0016] Where S′(x) represents the settlement value of any predicted point on the ground; V l represents the corrected stratum loss rate; R represents the radius of the shield machine; K represents the width parameter of the settlement trough; Z represents the tunnel depth; x represents the distance from the center of the settlement curve to the predicted point.

[0017] The present invention has the following beneficial effects: Different from the previous rock mechanics methods, by defining the range of the three zones of the caving zone, the fissure zone and the bending zone above the goaf, the damage state of the rock mass that the tunnel is to pass through after the goaf is formed by coal seam mining is grasped, that is, a stratigraphic profile is obtained based on the damage state after the first disturbance; and the stratigraphic loss rate under the condition of secondary disturbance of the rock mass caused by tunnel excavation is taken as the starting point, and the secondary disturbance of the surrounding rock is considered, and the stratigraphic loss rate of the entire bottom layer is fitted through a straight line based on the function coordinates one and the function coordinates two, and the relevant parameters in the traditional Peck formula are optimized and improved to predict surface settlement; this setting saves a lot of construction time and reduces a lot of costs when the tunnel passes through the existing goaf to actually predict the surface settlement, and at the same time can achieve accurate prediction, ensure the safety of tunnel construction through the goaf, and more safely and effectively protect ground buildings (structures). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic flow chart of a method for predicting ground subsidence caused by a tunnel passing through a goaf provided by one embodiment of the present invention;

[0020] Figure 2 A schematic diagram of rock mass division for a method for predicting surface subsidence caused by a tunnel passing through a goaf provided by an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of a stratum loss rate fitting function based on the tunnel position in a method for predicting surface subsidence caused by a tunnel passing through a goaf provided by an embodiment of the present invention;

[0022] Figure 4 A method for predicting surface subsidence caused by a tunnel passing through a goaf provided by an embodiment of the present invention is a schematic diagram comparing the stratum loss at the neutral axis of the bending zone above the goaf and the stratum loss in the non-goaf area, wherein (a) is the goaf and (b) is the non-goaf area. DETAILED DESCRIPTION

[0023] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the prediction method of surface subsidence caused by a tunnel passing through a goaf area proposed by the present invention, in combination with the accompanying drawings and preferred embodiments, as well as its specific implementation method, structure, features and effects. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0024] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0025] The specific scheme of the method for predicting surface subsidence caused by a tunnel passing through a goaf provided by the present invention is described in detail below in conjunction with the accompanying drawings.

[0026] Please combine Figure 1-Figure 4 , the goaf includes a roof, and the method includes:

[0027] Step 1: Determine the mining thickness and rock properties at the roof;

[0028] Step 2, establishing a stratigraphic profile of the caving zone, the fracture zone and the bending zone which are delineated in sequence along the axial direction based on the mining thickness and the rock properties near the goaf;

[0029] Step 3, determine the position of the neutral axis of the bending zone based on the stratigraphic profile, obtain the vertical distance between the neutral axis of the bending zone and the roof, calculate the stratum loss rate of the non-goaf area, and obtain the function coordinate 1 of the non-goaf area based on the vertical distance between the neutral axis of the bending zone and the roof and the stratum loss rate of the non-goaf area; obtain the rock expansion coefficient according to the rock properties, correct the stratum loss rate of the non-goaf area based on the expansion coefficient, and obtain the vertical distance between the neutral axis of the bending zone and the goaf, and the function coordinate 2 about the tunnel passing through the caving zone, fracture zone and bending zone on the goaf; perform linear fitting on the function coordinate 1 and the function coordinate 2 to construct the stratum loss rate function of the tunnel passing through the caving zone, fracture zone and bending zone on the goaf;

[0030] Step 4: According to the formation loss rate function and the Peck formula, the surface settlement prediction function is obtained to obtain the final surface settlement.

[0031] It can be explained that the embodiments of the present invention can be applied to horizontal coal seam mining and mining subsidence reaches full mining, or the impact range of tunnel construction is within the flat bottom area where surface subsidence is caused by mining.

[0032] Specifically, in step 1, geological exploration is carried out using advanced geological prediction technology to determine the mining thickness, and core samples are drilled to conduct on-site uniaxial compressive strength tests to determine the rock properties at the top of the goaf. If the test result shows that the uniaxial compressive strength is greater than 30 MPa, it is hard rock; if the uniaxial compressive strength is less than 30 MPa, it is soft rock.

[0033] Furthermore, the mining thickness is defined as h, the soil layer at the roof is 0h, and the rock properties include hard rock and soft rock. If the roof is hard rock, the caving zone is [0h, 5h], and the fracture zone is [5h, 13h]; if the roof is soft rock, the caving zone is [0h, 3h], and the fracture zone is [3h, 6h]; the bending zone is from the end of the fracture zone close to the surface to the surface.

[0034] This embodiment, through the height definition of the caving zone, the fracture zone and the bending zone, can well grasp the scope of the loosening of the layer after the mining activity, that is, the scope of the stratum crushing when the tunnel passes through, that is, grasp the heterogeneous characteristics of the stratum passed by the tunnel, so as to accurately predict the abnormal surface subsidence caused by the tunnel passing through the goaf.

[0035] For better explanation, in step 3, when the tunnel excavation center is at the neutral axis position above the goaf, it is assumed that the rock mass below the neutral axis produces a tensile strain ε t , the rock mass above the neutral axis produces compressive strain εc, among which the generation of tensile strain will increase the cracking and deformation of the rock, forming more voids inside the rock and increasing the stratum loss caused by tunnel excavation; while under the influence of compressive strain, the cracks inside the rock above the neutral axis are compacted, reducing the stratum loss.

[0036] The stratum loss in non-goaf areas is assumed to be a standard circle in many literatures. When the tunnel passes through the neutral axis of the goaf bending zone, the stratum loss will form an elliptical shape that is narrow at the top and wide at the bottom under the influence of the tensile and compressive strains of the rock. Because the tensile and compressive strains above and below the neutral axis are symmetrically distributed, the stratum loss when the tunnel passes through the neutral axis of the goaf bending zone is the same as that in the non-goaf area. The stratum loss in the non-goaf area also refers to the stratum loss under normal circumstances; above the neutral axis to the surface, the stratum loss is smaller than that in the non-goaf area; below the neutral axis, the stratum loss is larger than that in the non-goaf area.

[0037] As for the roof position, after the coal seam is mined, the coal seam roof is in a tensile state, and it first bends toward the goaf, and then breaks into rock blocks of varying sizes and falls downward; the falling rock has a certain degree of fragmentation and expansion, and the gaps between the falling rock blocks are relatively large; the fragmentation and expansion of the rock mass and the large voids caused by the fragmentation and expansion are bound to increase the formation loss, and the rock fragmentation and expansion coefficient depends on the properties of the rock, the hard rock fragmentation and expansion coefficient is larger, and the soft rock fragmentation and expansion coefficient is smaller; but the fragmentation and expansion coefficient is always greater than 1, generally between 1.05-1.80, so based on the rock fragmentation and expansion coefficient and the two points at the neutral axis position of the bending zone that have no effect on the formation loss, fitting is performed to determine the formation loss rate function above the goaf.

[0038] Furthermore, the function coordinate is (V 0 ,y 中 ); Function coordinate 2 is (kV 0 , 0); the formation loss rate function is:

[0039]

[0040] Among them, V l represents the corrected formation loss rate; k represents the expansion coefficient; V 0 represents the stratum loss rate in the non-mined area; y 中 It represents the vertical distance between the neutral axis of the bending zone and the roof; h represents the mining thickness.

[0041] Specifically, based on the obtained stratigraphic profile, the neutral axis position of the bending zone is determined. According to the definition of material mechanics, the neutral axis position of a rectangular cross-section beam is located at the midline of the cross section. If the bending zone height is Δx, the central axis position is at Then, the formation loss rate V under non-goaf conditions is calculated using the calculation formula of the formation loss rate in the original Peck formula. l ; Establish a y related to V l The function of the non-goaf area condition is obtained, that is, (V 0 ,y 中 ) is the function coordinate one, y 中 It indicates the vertical distance between the neutral axis of the bending zone and the goaf. In physical sense, it is the neutral axis position of the bending zone. According to the basic viewpoint of material mechanics, there is neither tensile strain nor compressive strain at the neutral axis of the bending structure, that is, no strain occurs. Therefore, the formation loss at this position is not affected. 0 Represents the formation loss rate under non-goaf conditions.

[0042] The definition k represents the rock expansion coefficient, which is the ratio of the volume of the rock in a loose state after being crushed to the volume of the rock in an integral state before being crushed. The volume of the rock after being crushed will be larger than that in the integral state, and this property is called the rock expansion. This value is called the expansion coefficient. The applicant has found that: near the excavation position of the tunnel roof, the rock stratum is most disturbed, and the voids caused by its expansion are also the largest in the entire stratum. Therefore, this embodiment uses the rock expansion coefficient to determine the stratum loss rate at the tunnel roof.

[0043] Specifically, according to the determined rock properties, the corresponding rock expansion coefficient k is obtained by referring to the rock expansion coefficient table in Table 1, and the expansion coefficient k is multiplied by the formation loss rate V under non-goaf conditions. 0 , and the corrected stratum loss rate kV is obtained when the tunnel passes through the caving zone above the goaf 0 , and y 中 Related to V l The function coordinate value, that is, (kV 0 ,0) is the function coordinate two.

[0044] Table 1 Rock expansion coefficient

[0045]

[0046] From the data analysis, the stratum loss caused by the tunnel through the caving zone is the greatest, followed by the fracture zone, and the smallest when passing through the bending zone; based on linear fitting based on function coordinates one and two, the stratum loss rate function of the tunnel passing through the caving zone, fracture zone and bending zone above the goaf is obtained, which is the stratum loss rate function of the tunnel passing through the goaf.

[0047] Furthermore, step 4 includes: obtaining a corrected formation loss rate through the formation loss rate function, calculating the surface subsidence in combination with the Peck formula, superimposing it with the original subsidence data caused by mining, obtaining a surface subsidence prediction function across the goaf, and obtaining the final surface subsidence.

[0048] Specifically, the corrected stratum loss rate is obtained through the stratum loss rate function, and the surface settlement is calculated by combining the Peck formula. The equipment used for the tunnel to pass through the goaf includes a shield machine and a settlement trough, among which the Peck classic formula is:

[0049]

[0050] Where S(x) represents the settlement value of any point on the ground, in mm; x represents the distance from the center of the settlement curve to the point to be calculated, in m; S maxIt represents the maximum value of ground settlement, located at the symmetry center of the settlement curve, corresponding to the position of the tunnel axis, and the unit is mm; i represents the distance from the symmetry center of the settlement curve to the inflection point of the curve, that is, the inflection point, usually refers to the width of the settlement trough, and the unit is m.

[0051] Based on the formation loss rate function and Peck's classical formula of tunnel passing through the caving zone, fracture zone and bending zone in the goaf, the S max The function formula is:

[0052]

[0053] Where V represents the unit formation loss, in m 3 / m;

[0054] Then the function formula of V is obtained as follows: Among them, V 0 It is expressed as the stratum volume loss rate under normal conditions, that is, the percentage of stratum loss per unit length to shield volume per unit length; R represents the shield radius, in meters;

[0055] The calculation formula for i is: i = KZ;

[0056] Among them, i represents the settlement trough width coefficient, the unit is m; K represents the settlement trough width parameter, which is related to the soil properties. According to the determined soil properties, the corresponding settlement trough width parameter K is obtained by referring to the settlement trough width parameter coefficient table in Table 2; Z represents the tunnel depth, the unit is m.

[0057] Finally, the sedimentation formula is:

[0058] The stratum loss rate function of the caving zone, fracture zone and bending zone above the goaf where the tunnel passes is substituted into the settlement formula to obtain the surface settlement prediction function for crossing the goaf.

[0059] Furthermore, the surface subsidence prediction function is:

[0060]

[0061] Where S′(x) represents the settlement value of any predicted point on the ground; V l represents the corrected stratum loss rate; R represents the radius of the shield machine; K represents the width parameter of the settlement trough; Z represents the tunnel depth; x represents the distance from the center of the settlement curve to the predicted point.

[0062] Understandably, the neural network model requires a large amount of data and a large number of identical working conditions, which results in the difficulty of data collection. In addition, the Peck formula is still the main method for calculating and estimating surface settlement in current projects. Although it is widely used in the problem of surface settlement caused by tunnel construction, it is only applicable to a single stratum that has not been disturbed. It has great limitations in predicting surface settlement caused by tunnels passing through goafs, and the accuracy requirements cannot be met. Different from the previous rock mechanics methods, by defining the three zones of the caving zone, the fracture zone and the bending zone above the goaf, the damage of the rock mass that the tunnel is going to pass through after the goaf is formed by coal mining is understood. state, that is, the destruction state after the first disturbance, to obtain the stratigraphic profile; combined with the properties of the bending zone, a certain extension is made, and the stratigraphic loss rate under the condition of secondary disturbance of the rock mass caused by tunnel excavation is taken as the starting point. Considering the secondary disturbance of the surrounding rock, the stratigraphic loss rate of the entire bottom layer is fitted through a straight line, and the relevant parameters in the traditional Peck formula are optimized and improved to predict the surface settlement; this setting saves a lot of construction time and reduces a lot of costs when the tunnel passes through the existing goaf to actually predict the surface settlement, and at the same time can achieve accurate prediction, ensure the safety of tunnel construction through the goaf, and protect the ground buildings (structures) more safely and effectively.

[0063] A prediction method for surface subsidence caused by a tunnel passing through a goaf proposed in this embodiment has been put into practical application. Specifically, it has been initially used in the Nanhang New Village-Xinshixu Station and Xinshixu-Baiyun Cultural Square Station section projects of Guangzhou Metro Line 12.

[0064] It can be explained that the degree of ground disturbance is relatively large when the shield tunnel passes through the goaf. After adopting the technical solution proposed in the present invention, after on-site inspection, no obvious stress deformation, damage, cracking and other abnormal phenomena were found in the outdoor platform, indoor floor and columns and wall footings of the surface buildings, nor were obvious deformation and cracking of the upper structure components caused by uneven settlement of the foundation. According to the on-site monitoring situation, the disturbance of the stratum during the entire shield excavation process in the section between Nanhang Xincun Station and Xinshixu Station caused the maximum surface settlement of 17.6mm, and no monitoring data warning occurred; the disturbance of the stratum during the entire shield excavation process in the section between Xinshixu Station and Baiyun Cultural Square caused the maximum surface settlement of 23.2mm, and no monitoring data warning occurred. This shows that the establishment and application of the prediction method for surface settlement caused by tunnel crossing the goaf effectively controls the surface settlement and the risk of building collapse in the area passed by the tunnel, reduces building damage, helps the construction team avoid unnecessary additional losses, and enables on-site construction to proceed smoothly.

[0065] For the sake of simplicity of calculation and more representativeness of the project, the maximum point of surface settlement caused by tunnel construction is used, that is, the position of the tunnel centerline. The above maximum surface settlement is also based on the position of the tunnel centerline, so the in-table monitoring data of the section between Nanhang Xincun Station and Xinshixu Station and the section between Xinshixu Station and Baiyun Cultural Square are also the maximum settlement values.

[0066] According to the on-site construction data, the width of the settlement trough between Nanhang Xincun Station and Xinshixu Station is 5.43m, and the volume loss rate of the stratum at this location in the non-mining state is V 0 is 203.625m 3 / m, and the width of the settlement trough i between Xinshixu Station and Baiyun Cultural Square is 4.46m. According to the on-site regression analysis, the stratum volume loss rate V under normal circumstances is 0 is 223.

[0067] Based on the above basic on-site construction data, it can be obtained that the maximum value of the construction settlement at this location is predicted to be:

[0068] Between Nanhang Xincun Station and Xinshixu Station

[0069] Xinshixu Station - Baiyun Cultural Square Section

[0070] The prediction of the maximum construction settlement of the location by the method of the present invention is:

[0071] According to the rock fragmentation and expansion conditions at the site and the location of the tunnel, k = 1.12V is calculated. l is 228.06;

[0072] Between Nanhang Xincun Station and Xinshixu Station

[0073] According to the rock expansion on site and the location of the tunnel, k = 1.125V is calculated. l is 250.875;

[0074] Xinshixu Station - Baiyun Cultural Square Section

[0075] By comparing Table 3 and Table 4, it can be seen that the actual measured settlement value of the section between Nanhang Xincun Station and Xinshixu Station is -17.6mm, the traditional prediction method is -15mm, and the predicted value of the present invention is -16.8mm. The actual measured settlement value of the section between Xinshixu Station and Baiyun Cultural Square is -23.2mm, the traditional prediction method is -20mm, and the predicted value of the present invention is -22.5mm, both of which are more accurate than the traditional prediction method.

[0076] Table 3 On-site characteristic monitoring data between Nanhang New Village and Xinshi Market

[0077]

[0078] Table 4 On-site characteristic monitoring data of Xinshixu-Baiyun Cultural Square section

[0079]

[0080] Based on the above description, a prediction method for surface subsidence caused by tunnel passing through goaf is proposed, which can comprehensively and accurately predict surface subsidence. This not only improves the safety and stability of the project, but also provides a useful reference and reference for predicting surface subsidence when other tunnels pass through goaf at home and abroad.

[0081] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0082] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A method for predicting ground subsidence caused by a tunnel passing through a goaf, wherein the goaf includes a roof, characterized in that: The method comprises: Step 1: Determine the mining thickness and rock properties at the roof; Step 2, establishing a stratigraphic profile of the caving zone, the fracture zone and the bending zone which are delineated in sequence along the axial direction based on the mining thickness and the rock properties near the goaf; Step 3, determine the position of the neutral axis of the bending zone based on the stratigraphic profile, obtain the vertical distance between the neutral axis of the bending zone and the roof, calculate the stratum loss rate of the non-goaf area, and obtain the function coordinate 1 of the non-goaf area based on the vertical distance between the neutral axis of the bending zone and the roof and the stratum loss rate of the non-goaf area; obtain the rock expansion coefficient according to the rock properties, correct the stratum loss rate of the non-goaf area based on the expansion coefficient, and obtain the vertical distance between the neutral axis of the bending zone and the goaf, and the function coordinate 2 about the tunnel passing through the caving zone, fracture zone and bending zone on the goaf; perform linear fitting on the function coordinate 1 and the function coordinate 2 to construct the stratum loss rate function of the tunnel passing through the caving zone, fracture zone and bending zone on the goaf; Step 4: According to the formation loss rate function and the Peck formula, the surface settlement prediction function is obtained to obtain the final surface settlement.

2. The method for predicting ground subsidence caused by a tunnel passing through a goaf as claimed in claim 1, characterized in that: The mining thickness is defined as h, the soil layer at the roof is 0h, and the rock properties include hard rock and soft rock. If the roof is hard rock, the caving zone is [0h, 5h], and the fracture zone is [5h, 13h]; if the roof is soft rock, the caving zone is [0h, 3h], and the fracture zone is [3h, 6h]; the bending zone is from the end of the fracture zone close to the surface to the surface.

3. The method for predicting ground subsidence caused by a tunnel passing through a goaf as claimed in claim 1, characterized in that: The function coordinate 1 is (V0,y 中 ); the function coordinate 2 is (kV0,0); the formation loss rate function is: Among them, V l represents the corrected formation loss rate; k represents the expansion coefficient; V0 represents the formation loss rate in the non-goaf area; y represents the vertical distance between the neutral axis of the bending zone and the roof; h represents the mining thickness.

4. The method for predicting ground subsidence caused by a tunnel passing through a goaf as claimed in claim 1, characterized in that: Step 4 includes: obtaining the corrected formation loss rate through the formation loss rate function, calculating the surface subsidence in combination with the Peck formula, superimposing it with the original subsidence data caused by mining, obtaining the surface subsidence prediction function across the goaf, and obtaining the final surface subsidence.

5. The method for predicting ground subsidence caused by a tunnel passing through a goaf as claimed in claim 4, characterized in that: The equipment used for tunneling through the goaf includes a shield machine and a settlement trough. The surface settlement prediction function is: Where S′(x) represents the settlement value of any predicted point on the ground; V l represents the corrected stratum loss rate; R represents the radius of the shield machine; K represents the width parameter of the settlement trough; Z represents the tunnel depth; x represents the distance from the center of the settlement curve to the predicted point.

Images