Vibration reduction method for shield construction of composite stratum

Abstract

The embodiment of the invention discloses a vibration reduction method for shield construction of a composite stratum. An elastic material with the elasticity modulus being E and the density being # imgabs0 # is used for manufacturing a hollow cylindrical vibration isolation pad with the height being L, the outer diameter being D and the inner diameter being d. A vibration reduction hole distribution area is divided between the residential area and the shield tunnel, a plurality of rows of vibration reduction holes are formed in the vibration reduction hole distribution area, the vibration reduction holes are filled with the vibration isolation pads, and the hole depth of the vibration reduction holes reaches the bottom of the tunnel face; and according to different vibration reduction effects, parameters of vibration isolators filled subsequently are adjusted. By the adoption of the vibration reduction device, the vibration reduction hole distribution area is arranged, the vibration reduction holes are filled with the elastic vibration isolation materials, and vibration reduction setting and materials are dynamically adjusted and optimized according to actually-measured vibration data, so that the vibration reduction effect and the environmental adaptability are improved.

Description

Technical Field

[0001] The invention relates to underground tunnel construction technology, and in particular to a vibration reduction method for composite stratum shield construction. Background Art

[0002] As an advanced underground tunnel construction technology, shield tunneling is widely used in urban rail transit construction. Shield construction has the advantages of high efficiency, rapidity, suitability for various geological conditions and little interference with ground traffic. However, the early shield tunneling construction and the later train operation will generate vibration and noise, and may affect the lives of surrounding residents and buildings. The vibration of shield tunneling is mainly caused by the shield machine cutter cutting the rock mass and propagates through the surrounding strata, causing secondary vibration and noise problems in neighboring buildings, and may also cause structural damage to the buildings.

[0003] At present, the industry has taken some measures to minimize the negative impact of vibration in response to the vibration problem during shield excavation. The most common method is to excavate concrete hollow piles, that is, to lay certain vibration reduction holes or vibration reduction trenches on the path from the tunnel to the residential area. In addition, another method often used by construction teams is to adjust the shield excavation parameters or set a vibration reduction layer on the inner wall of the tunnel. This method focuses on processing at the vibration source, and the defects are: 1. A single vibration reduction hole can only block and absorb the energy of stress waves through a vibration reduction tube, and cannot effectively target vibrations of different frequencies 2. The design of the vibration reduction belt is usually based on experience, and the arrangement method is not scientific enough for different working conditions 3. Reducing vibration by reducing shield parameters such as cutter head speed and cutter head torque will affect construction efficiency and delay construction progress. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a vibration reduction method for shield construction in composite strata, by filling elastic vibration isolation materials in the vibration reduction holes, and dynamically adjusting and optimizing the vibration reduction settings and materials according to the measured vibration data, so as to improve the vibration reduction effect and environmental adaptability.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a vibration reduction method for composite stratum shield construction, comprising the following steps: S1: Use elastic modulus E and density A hollow cylindrical vibration isolation pad with a height of L, an outer diameter of D, and an inner diameter of d is made of elastic material; in, ; ; f b is the first-order bending natural frequency, f a is the first-order axial natural frequency; S2: A vibration reduction hole layout area is divided between the residential area and the shield tunnel, and a plurality of rows of vibration reduction holes are arranged in the vibration reduction hole layout area. The vibration reduction holes are filled with the vibration isolation pads, and the hole depth of the vibration reduction holes reaches the bottom of the tunnel surface.

[0006] A further preferred embodiment is that the vibration-damping holes are arranged in a honeycomb shape, and each vibration-damping hole is located at the center of a preset regular hexagon.

[0007] A further preferred method is that the locations of the vibration-damping holes are determined in the following manner: ; in, is the horizontal distance between the first row of vibration reduction holes and the tunnel, It is the preset coefficient factor, the default value is 1; The spacing between the vibration-damping holes is determined as follows: ; in, is the spacing between vibration reduction holes, It is a preset coefficient factor, which is less than 1 / 6 for underground vibration.

[0008] A further better way is that after the vibration reduction holes are arranged, the holes are filled, the last row of vibration reduction holes is filled, and the filling heights of the remaining rows of vibration reduction holes are determined by the following formula: (7) Wherein, h is the filling height, i is the number of rows of vibration-damping holes, x is the horizontal distance from each row of vibration-damping holes to the tunnel, and k3 is a preset factor, which is dynamically adjusted according to vibration monitoring.

[0009] A further preferred method is that the width of the vibration reduction hole arrangement area is RS, S is the horizontal straight-line distance between the residential area and the tunnel, and R is the vibration influence radius of the shield construction.

[0010] A further preferred embodiment is that the number of rows of the vibration-damping hole cloth is 3-5 rows.

[0011] A further preferred embodiment is that the natural frequency of the vibration isolation pad is less than 100 Hz.

[0012] The implementation of the embodiment of the present invention has the following beneficial effects: by setting a vibration reduction hole layout area, filling the vibration reduction holes with elastic vibration isolation materials, and dynamically adjusting and optimizing the vibration reduction settings and materials according to the measured vibration data, the vibration reduction effect and environmental adaptability are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic flow diagram of the method of the present invention; Figure 2 It is a schematic diagram of the scene of the implementation of the method of the present invention; Figure 3 It is a structural diagram of a vibration pad; Figure 4 It is a structural diagram of the arrangement of vibration-damping holes. DETAILED DESCRIPTION

[0014] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0015] like Figure 1 As shown, a vibration reduction method for composite stratum shield construction according to an embodiment of the present invention is implemented through the following steps.

[0016] Step 1: The design method of the vibration isolation pad is implemented in the following way.

[0017] The elastic modulus is E and the density is A hollow cylindrical vibration isolation pad with a height of L, an outer diameter of D, and an inner diameter of d is made of elastic material.

[0018] During the shield tunneling process, more shear waves will be generated in the stratum, causing bending vibrations, which are manifested as low-frequency and high-amplitude vibrations within the vibration frequency range. Shear waves are shear waves, which make the stratum vibrate back and forth and left and right, and are highly destructive. The natural frequency of the elastic material in the bending vibration mode should match the low frequency generated by the shield tunneling. The calculation formula for the first-order natural frequency in the bending vibration mode is: (1) in, f b is the first-order bending natural frequency, is the length of the hollow cylindrical vibration isolation pad, is the elastic modulus of the vibration isolation pad, is the density of the vibration isolation pad, D is the outer diameter of the vibration isolation pad. When it fits tightly against the vibration reduction hole, the outer diameter D of the vibration isolation pad is equal to the diameter of the vibration reduction hole, the latter of which is generally 0.2m~0.4m, and d is the inner diameter of the vibration isolation pad.

[0019] Although the vibrations generated by shield tunneling are mainly transverse waves, there are also certain longitudinal waves, which cause the ground to vibrate up and down, manifesting as high-frequency and high-amplitude vibrations within the vibration frequency range. The axial vibration natural frequency of the vibration isolation pad can help reduce the transmission of these vibrations. The calculation formula for the first-order natural frequency in the axial vibration mode is: (2) in, f a is the first-order axial natural frequency, is the density of the vibration isolation pad.

[0020] From formula (2), we get: (3) From formula (1), we can get: (4) The height L of the vibration isolation pad is determined by formula (3), and the inner diameter d of the vibration isolation pad is determined by formula (4), and then the thickness (Dd) of the vibration isolation pad is obtained.

[0021] The parameters of the vibration isolation pad can be calculated by the density and elastic modulus of the material used. In a more preferred embodiment, environmentally friendly materials with high elasticity and high damping, such as waste tires, can be used as vibration isolation pads as long as their shape is changed.

[0022] Step 2: The vibration reduction hole arrangement method is implemented through the following steps.

[0023] The vibration reduction hole layout area is divided between the residential area and the shield tunnel. Based on the conclusion that "when a plane is covered with circles of the same radius, the number of circles used is the least when the center of the circle is at the center of each regular hexagon of the regular hexagonal grid, that is, when the center of the circle is at the grid point of the regular triangle grid", a honeycomb layout is adopted. Each vibration reduction hole is at the center of a preset regular hexagon. The hole diameter should be slightly larger than the outer diameter of the vibration isolation pad, and the hole depth should reach the bottom of the tunnel surface. The distance between the construction area and the residential area is marked as S, the vibration influence range of the shield construction is marked as R, and the vibration stratum wave velocity is marked as v.

[0024] The location of the vibration reduction holes is determined as follows: (5) in, is the horizontal distance between the first row of vibration reduction holes and the tunnel, It is a preset coefficient factor, the default value is 1, and it can be flexibly adjusted according to the surface environment.

[0025] The spacing of the vibration reduction holes is determined as follows: (6) in, is the spacing between vibration reduction holes, The preset coefficient factor should be less than 1 / 6 for underground vibration.

[0026] After the vibration reduction holes are laid out, fill the holes. The last row of vibration reduction holes should be filled. The filling height of the remaining rows of vibration reduction holes is determined by the following formula: (7) Wherein, h is the filling height, i is the number of rows of vibration-damping holes, x is the horizontal distance from each row of vibration-damping holes to the tunnel, and k3 is a preset factor, which is dynamically adjusted according to vibration monitoring.

[0027] The height of the vibration isolation pad decreases from near to far on one side of the building. The overall layout of the vibration reduction holes is a honeycomb layout, and its spacing is more scientific and has nothing to do with the filling material, but its hole diameter is consistent with the size of the filling material (i.e., the vibration isolation pad).

[0028] The area where the vibration-damping holes are arranged is located in the soil layer between the shield tunnel and the residential area, and the range is usually determined by the vibration impact range of the tunnel on the stratum and the sensitivity of the residential area.

[0029] The width of the vibration reduction hole layout area is RS, S is the horizontal straight-line distance between the residential area and the tunnel, and R is the vibration influence radius of the shield construction.

[0030] Layout area design principles: Energy absorption priority: The deployment area covers all vibration wave paths that may propagate to residential areas.

[0031] Multi-layer attenuation: Multiple rows of vibration-damping holes disperse vibration energy to avoid the insufficient effect of a single-row setting.

[0032] Number of rows N: Determined dynamically based on the vibration impact range of shield construction and the sensitivity of residential areas, usually set to 3 to 5 rows.

[0033] First row: on the side close to the tunnel, used to directly absorb vibration.

[0034] Subsequent rows: gradually approaching residential areas to further attenuate remaining vibrations.

[0035] Step 3: Dynamic adjustment of vibration reduction hole filling: The filling of vibration isolation pads is dynamically adjusted according to the real-time vibration monitoring of residential buildings. The parameters of the subsequent vibration isolation pads are adjusted according to different vibration reduction effects. The different filling heights of vibration reduction holes in each row are combined to achieve the best vibration reduction effect while saving filling materials.

[0036] In an embodiment of the present invention, the vibration isolation pad is made of highly elastic, high-damping recycled environmentally friendly materials, such as waste tires, so that it has good energy absorption characteristics. By adjusting the thickness and size of the vibration isolation pad, its natural frequency can be dynamically adjusted within the range of 0-100Hz.

[0037] According to the elastic modulus and density of different materials, the material size is adjusted through the above formula to match the specific vibration frequency to achieve the maximum vibration reduction effect.

[0038] The vibration frequency generated by shield construction varies according to the differences in the strata and the tool settings, and its range is mainly between 0 and 60 Hz. By using the following design method, the natural frequency of the filling material is consistent with the shield tunnel, which can effectively cause resonance, so elastic high damping materials have good applicability.

[0039] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A vibration reduction method for shield construction in composite strata, characterized in that: The following steps are involved: S1: Use elastic modulus E and density A hollow cylindrical vibration isolation pad with a height of L, an outer diameter of D, and an inner diameter of d is made of elastic material; in, ; ; f b is the first-order bending natural frequency, f a is the first-order axial natural frequency; S2: A vibration reduction hole layout area is divided between the residential area and the shield tunnel, and a plurality of rows of vibration reduction holes are arranged in the vibration reduction hole layout area. The vibration reduction holes are filled with the vibration isolation pads, and the hole depth of the vibration reduction holes reaches the bottom of the tunnel surface.

2. The vibration reduction method for composite stratum shield construction according to claim 1 is characterized in that: The vibration-damping holes are arranged in a honeycomb shape, and each vibration-damping hole is located at the center of a preset regular hexagon.

3. The vibration reduction method for composite stratum shield construction according to claim 2 is characterized in that: The vibration reduction hole arrangement position is determined in the following manner: ； in, is the horizontal distance between the first row of vibration reduction holes and the tunnel, It is the preset coefficient factor, the default value is 1; The spacing between the vibration-damping holes is determined as follows: ； in, is the spacing between vibration reduction holes, It is a preset coefficient factor, which is less than 1 / 6 for underground vibration.

4. The vibration reduction method for composite stratum shield construction according to claim 3 is characterized in that: After the vibration reduction holes are arranged, they are filled in the holes. The last row of vibration reduction holes is filled fully, and the filling heights of the remaining rows of vibration reduction holes are determined by the following formula: Wherein, h is the filling height, i is the number of rows of vibration-damping holes, x is the horizontal distance from each row of vibration-damping holes to the tunnel, and k3 is a preset factor, which is dynamically adjusted according to vibration monitoring.

5. The vibration reduction method for composite stratum shield construction according to claim 4 is characterized in that: The width of the vibration reduction hole arrangement area is RS, S is the horizontal straight-line distance between the residential area and the tunnel, and R is the vibration influence radius of the shield construction.

6. The vibration reduction method for composite stratum shield construction according to claim 4 is characterized in that: The number of rows of the vibration-damping hole cloth is 3-5 rows.

7. The vibration reduction method for composite stratum shield construction according to any one of claims 1 to 6, characterized in that: The natural frequency of the vibration isolation pad is less than 100 Hz.

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