A seismic isolation trench system for mitigating the influence of an existing railway on the excavation of a foundation pit in a neighboring area

Abstract

The present application relates to a kind of shock isolation ditch systems for reducing the influence of existing railway on adjacent area foundation pit excavation, including the shock isolation device in the shock isolation ditch between railway and adjacent foundation pit, the shock isolation device includes: two shock isolation arms connected by connecting piece, respectively abutting on the opposite two support row piles of the shock isolation ditch, each shock isolation arm includes shock isolation support, elastic rubber pad, bar and bottom plate, wherein the shock isolation support includes lead core, steel ring and functional rubber ring are alternately arranged on lead core;A pair of energy absorbers, one end is movably connected with the connecting piece, the other end is connected with the contact point of the support row pile and the damping support of shock isolation ditch bottom face.Compared with prior art, the present application has the advantages of improving shock isolation efficiency and structural stability, enhancing system durability, adapting to diversified vibration scenarios, good environmental adaptability and maintainability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vibration isolation and foundation pit construction, and particularly relates to a vibration isolation trench system for reducing the influence of an existing railway on a nearby area foundation pit excavation. BACKGROUND

[0002] With the rapid development of urban rail transit and railway network, deep foundation pit projects adjacent to existing railway lines are increasing. This requires consideration and evaluation of the influence of foundation pit excavation on existing buildings, as well as the adoption of appropriate protective measures. It is more common that when deep foundation pit excavation is carried out next to an existing railway line, soil unloading and construction vibration can easily lead to track deformation or roadbed settlement, threatening train safety. Similarly, the periodic dynamic load effect generated by train operation can be transmitted to the foundation pit support structure through the soil, which may cause resonance instability of the support system. Traditional vibration isolation trenches use a single filling material or simple support structure, which has limited vibration reduction effect and is easily affected by groundwater.

[0003] In recent years, composite vibration isolation structures have become a research hotspot. For example, the combination of elastic materials and rigid frames can improve the isolation efficiency, and prefabricated components can shorten the construction period and enhance the stability of the structure. However, the use of vibration isolation trenches also requires some conditions. The construction process of the vibration isolation trench also involves excavating soil, and appropriate support measures should be taken for the vibration isolation trench. In addition, the support components in the vibration isolation trench provide bearing capacity while also conducting vibration, thereby weakening the vibration isolation effect of the vibration isolation trench. On the other hand, in some cases, in order to achieve the ideal vibration isolation effect, the vibration isolation trench needs a large excavation depth, which will increase the construction and building costs. At the same time, in order to ensure good vibration isolation effect, the vibration isolation trench needs to be located at a distance from the foundation pit, and the length is generally greater than the length of the foundation pit. However, in actual engineering, due to site conditions, there is often not enough distance between the existing railway and the adjacent foundation pit.

[0004] Chinese Patent Application Publication No. CN104452999A discloses a self-displacement vibration isolation trench system, which introduces elastic damping displacement support rods and sliding limiting devices into the vibration isolation trench to achieve self-displacement of the cover plate of the vibration isolation trench, solves the problem of limited deformation of the cover plate in the existing vibration isolation trench during an earthquake, improves the vibration isolation effect, and simplifies the construction process. However, this application is aimed at vibration isolation in the context of dramatic geological changes such as lifting, extrusion, or displacement deformation, and relies on the setting of support ends on the cover plate and side walls, which is not ideal for vibration isolation in the context of foundation pit excavation adjacent to a railway, and is inconvenient to set.

[0005] In summary, there is currently a lack of a vibration isolation trench system for the context of foundation pit excavation adjacent to a railway. SUMMARY

[0006] The present application aims to overcome the defects of the prior art and provide a shock isolation trench system for reducing the influence of an existing railway on the excavation of a foundation pit in a nearby area, so as to solve the problem of how to reduce the influence on the foundation pit under the complex site environment condition of the excavation of a foundation pit in the vicinity of a railway.

[0007] The object of the present application can be achieved by the following technical solutions:

[0008] The present application provides a shock isolation trench system for reducing the influence of an existing railway on the excavation of a foundation pit in a nearby area, comprising a shock isolation device arranged in a shock isolation trench between the railway and the nearby foundation pit, wherein the shock isolation device comprises:

[0009] Two shock isolation arms connected by a connecting piece are respectively abutted on the opposite two support row piles of the shock isolation trench, each shock isolation arm comprises a shock isolation support, an elastic rubber pad, a rod and a bottom plate, wherein the shock isolation support comprises a lead core, a steel ring and a functional rubber ring arranged alternately on the lead core, the elastic rubber pad is sleeved on both ends of the lead core and abuts against the steel ring at the end of the shock isolation support.

[0010] A pair of energy absorbers are movably connected to the connecting piece at one end and connected to the damping support at the contact point between the support row pile and the bottom surface of the shock isolation trench at the other end.

[0011] As a preferred technical solution, one end of the shock isolation support bears the vibration force transmitted by the rod, consumes vibration energy through up and down displacement, suppresses the isolation of vertical vibration, the connecting piece is used to transmit horizontal axial force and vertical shear force, disperse the vibration energy to the energy absorber, the elastic rubber pad is used to consume horizontal vibration energy through buffering and reduce the wear of the steel ring at the end of the shock isolation support, and the energy absorber is used to consume vertical and horizontal energy, resist axial force and shear force, and play a supporting role.

[0012] As a preferred technical solution, the natural vibration frequency of the shock isolation device is less than 5.8Hz, the radius of the functional rubber ring is 50cm, the radius of the steel ring is 50cm, the radius of the lead core is 10cm, the thickness of the functional rubber ring is 2cm, the number of the functional rubber ring is 25, the thickness of the steel ring is 1cm, and the number of the steel ring is 26.

[0013] As a preferred technical solution, the length of the shock isolation trench is greater than the length of the long side of the excavated foundation pit, the depth is greater than the depth of the excavated foundation pit, and the strength and stiffness of the foundation pit support cast-in-place pile are higher than those of the shock isolation trench support row pile.

[0014] As a preferred technical solution, a plurality of pairs of support row piles are uniformly and spacedly arranged in the shock isolation trench along the length direction of the shock isolation trench, and each pair of support row piles is provided with a shock isolation device.

[0015] As a preferred technical solution, any one of the energy dissipators includes a rotatable support rod, a cylinder sealed with a viscous medium, and a piston cooperating with the cylinder. The other end of the support rod is connected to the damping support. When the energy dissipator is subjected to axial force, the movement of the support rod pushes the piston to reciprocate, causing the viscous medium in the cylinder to expand or compress, consuming vibration energy and suppressing the vibration effect. The damping support is used to suppress the amplification effect of the vibration load caused by the sudden change in the direction of the local interface after the excavation of the isolation trench.

[0016] As a preferred technical solution, it also includes:

[0017] A waterproof cover plate is arranged across the two opposite supporting pile rows of the seismic isolation ditch to seal the seismic isolation ditch, and the bottom of the drainage ditch is coated with waterproof material.

[0018] As a preferred technical solution, the base plate is connected to the supporting piles through bolt fasteners.

[0019] As a preferred technical solution, the rod is a hollow circular alloy steel rod, and the connecting piece is a steel connecting piece.

[0020] As a preferred technical solution, the two seismic isolation arms are symmetrically arranged with the connecting member as the center.

[0021] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0022] (1) Improve seismic isolation efficiency and structural stability: In view of the problem that traditional seismic isolation trenches rely on rigid components, have high vibration transmission rates, poor seismic isolation effects, and a single structure is difficult to cope with vertical and horizontal vibrations at the same time, the present invention adopts a composite structure of rods, seismic isolation supports, energy dissipators, and damping supports instead of traditional single rigid support rods. The seismic isolation supports consume vertical vibration energy through up and down displacement, the energy dissipators consume vertical and horizontal energy through piston compression of viscous media, the damping supports buffer the vibration amplification effect, and the elastic rubber pads consume horizontal vibration energy, thereby realizing the coordinated consumption of multi-directional vibration energy. The seismic isolation rate for multiple frequency bands, especially high-frequency vibrations, is high. The composite structure also has a supporting function, ensuring the stability of the seismic isolation trench and pile rows, and avoiding structural instability caused by vibration.

[0023] (2) Enhance system durability: for the traditional filling material class isolation measures in soil deformation after the failure, unable to adapt to the process of foundation pit excavation soil displacement, resulting in the loss of isolation function problem, the invention uses light high strength hollow alloy steel pole to improve toughness, based on the function of rubber ring and lead core series structure of large deformation capacity of isolation bearing, and the energy absorber of rotatable piston, cooperate with box-shaped steel connecting piece, the toughness of steel pole, the large deformation capacity of bearing and energy absorber, and the stress regulation effect of steel connecting piece, so that the system can still maintain the structural integrity when the soil displacement occurs, and continue to play the supporting and isolation effect, avoid the failure caused by soil deformation.

[0024] (3) Adapt to diversified vibration scene: for the problem that the parameter design of traditional isolation trench is fixed, it is difficult to adapt to the diversified vibration frequency of train and construction equipment, and the parameter control flexibility is low, the invention can realize accurate control of different frequency vibration by adjusting the area, number, thickness of functional rubber ring and the thickness ratio (such as beta value) of steel ring, the area ratio (such as alpha value) of lead core and rubber ring and other parameters, which can optimize the parameters for different vibration frequencies, increase the thickness or number of rubber ring to reduce the natural frequency of the system, and can improve the isolation rate in low frequency band. Parameter adjustment is flexible, which can realize the best proportion through intelligent design, meet the vibration control demand of complex site.

[0025] (4) Good environmental adaptability and maintainability: for the problem that the traditional isolation trench is easy to accumulate water, which leads to slope instability and reduces the isolation effect; and the high degree of component integration requires overall removal and maintenance, which is low in construction efficiency, the invention sets up waterproof cover plate to drain rainwater and drainage ditch coated with waterproof material at the bottom to prevent water accumulation, each component is connected through bolt fastener and steel connecting piece, and the steel connecting piece is reserved with gap for easy disassembly, the waterproof cover plate and drainage ditch work together to avoid water accumulation affecting the isolation function, the modular design enables single component to be independently disassembled and replaced, so that the whole plant does not need to be stopped for maintenance, which is suitable for complex environment such as rainy day, improves the construction efficiency and service life of the system. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a sectional view of the isolation trench system in the embodiment;

[0027] Figure 2 is a perspective view of the isolation trench device in the embodiment;

[0028] Figure 3 is a sectional view of the energy absorber in the embodiment,

[0029] Wherein, 1, rod, 2, bolt fastener, 3, connecting piece, 4, shock isolation support, 5, bottom plate, 6, elastic rubber pad, 7, energy absorber, 8, support row pile, 9, support rod, 10, damping support, 11, drainage ditch, 12, waterproof cover plate, 13, foundation pit support cast-in-place pile, 14, steel ring, 15, functional rubber ring, 16, viscous medium, 17, piston. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0032] In view of the problems of the prior art described above, the present embodiment provides a shock isolation trench system for reducing the influence of an existing railway on the excavation of a foundation pit in the adjacent area, to realize multi-mechanism collaborative damping, adapt to soil deformation and ensure the stability of the roadbed and the foundation pit. The system first ensures the preliminary stability of the shock isolation trench and the foundation pit wall by driving in cast-in-place piles. Then, the rigid connecting rod is used for supporting. At the same time, in order to reduce the vibration transmission caused by the support and weaken the damping effect, the rigid connecting rod is connected with the energy dissipation damper, so that the connecting rod can not only provide sufficient support force to prevent the foundation pit and the roadbed from being unstable, but also can maximize the consumption of vibration energy and reduce the influence of the railway on the foundation pit. Finally, the waterproof cover plate can effectively deal with the construction situation in rainy days, and can effectively prevent the water accumulation in the shock isolation trench from affecting the shock isolation effect of the shock isolation trench.

[0033] Reference Figure 1 and Figure 2, the shock isolation trench system comprises an alloy steel rod 1, a bolt fastener 2, a steel connecting piece 3, a shock isolation support 4, a bottom plate 5, an elastic rubber pad 6, an energy absorber 7, a supporting row pile 8, a supporting rod 9, a damping support 10, a drainage trench 11, a waterproof cover plate 12, a foundation pit support cast-in-place pile 13, a steel ring 14, a functional rubber ring 15, a viscous medium 16 and a piston 17.

[0034] The rod 1 is a hollow circular steel rod with high strength and light weight, one end of which is connected and fixed with the supporting row pile 8 of the shock isolation trench through the bolt fastener 2, and the other end is connected with the shock isolation support 4 through the bolt fastener 2, and is symmetrically arranged in the shock isolation trench. The alloy steel rod plays a role in connecting the shock isolation component and the row pile, and also plays a role in supporting the row pile to ensure the stability of the row pile.

[0035] There are four bolt fasteners for each bottom plate, and the alloy steel rod (i.e. the rod 1), the shock isolation support, the steel connecting piece and the energy absorber are connected and reinforced through bolts and the bottom plate.

[0036] The steel connecting piece 3 is box-shaped, has bolt connection entrances on both sides, and has a certain gap at the lower part, so as to facilitate the installation and removal of the shock isolation support and the damping support. In addition, the connecting piece 3 can transmit horizontal axial force and vertical shear force, and disperse the vibration energy to the energy absorber 7 below.

[0037] The shock isolation support 4 can bear the vibration force transmitted by the alloy steel rod, can consume part of the vibration energy through up and down displacement, and plays a role in isolating vertical vibration.

[0038] The elastic rubber pad 6 plays a buffering role, can consume horizontal vibration energy, and can prevent the functional rubber ring 15 at the end of the shock isolation support from being prematurely worn out.

[0039] The energy absorber 7 can consume vertical and horizontal energy, can resist axial force and shear force, and plays a supporting role.

[0040] A plurality of pairs of supporting row piles 8 are uniformly and interval ly arranged in the shock isolation trench along the length direction of the shock isolation trench, and the shock isolation device composed of the rod 1, the shock isolation support 4, the steel connecting piece 3 and the energy absorber 7 is arranged between the supporting row piles 8 on both sides of the shock isolation trench. The inner wall of the shock isolation trench is poured with concrete to form a protection wall. The cross-sectional shape of the shock isolation trench is rectangular, and the row piles on both sides of the trench are constructed first, and then reinforced after the construction of the row piles is completed, and the reinforcement is made of concrete mortar.

[0041] The strength and rigidity of the foundation pit support cast-in-place pile 13 are higher than those of the shock isolation trench supporting row pile 8, and the foundation pit is constructed strictly in accordance with the foundation pit construction specification, so as to ensure the stability and safety of the whole and local foundation pit.

[0042] The length of the shock isolation trench is greater than the length of the long side of the excavated foundation pit, and the depth is greater than the depth of the excavated foundation pit, so as to ensure the overall shock isolation effect.

[0043] The damping support 10 can reduce stress concentration and reduce the local vibration amplification effect caused by the isolation trench excavation.

[0044] The waterproof cover plate 12 can prevent rainwater from entering the isolation trench, causing water accumulation in the isolation trench, affecting the isolation effect, and on the other hand, it can carry pedestrians to avoid falling into the isolation trench, improving road safety and aesthetics. In addition, the bottom of the drainage ditch is coated with waterproof material, which can smoothly drain rainwater and prevent rainwater from seeping into the isolation trench and causing slope instability.

[0045] The isolation support 4 includes a functional rubber ring 15, an alloy steel ring 14, a lead core, and a positioning bolt. The functional rubber ring 15 is made of natural rubber and has good isolation and energy dissipation capacity. The steel ring 14 and the functional rubber ring 15 are alternately stacked, and the lead core connects the functional rubber ring 15 and the steel ring 14 together to play a role in isolation, and also serves as a support to resist axial force and vertical shear force, preventing the isolation support from disintegrating and damaging under the action of vibration load.

[0046] Referring to Figure 1 and Figure 3 , the energy absorber 7 includes a damping support 10, a support rod 9, a piston 17, a cylinder, and a viscous medium 16. The support rod 9 pushes the piston to move when under stress, and the viscous medium is driven by the piston to dissipate energy. The damping support 10 is fixed to the bottom of the isolation trench through the bolt fastener 2 below, and the damping support 10 is used to buffer the amplification effect caused by the vibration load. The cylinder is filled with viscous medium 16, which is sealed by the piston 17. When the support rod 9 is under axial force, it pushes the piston 17 to compress the viscous medium 16, which dissipates vibration energy during compression. The energy absorber 7 has a ring buckle at each end for connecting the damping support 10 and can rotate. The piston 17 seals the viscous medium 16 in the cylinder.

[0047] The working principle of the system is that when a train passes on the left railway, the railway is subjected to a vibration load, and the vibration effect generated by the load causes the whole side of the shock isolation trench to produce vertical vibration in the propagation process. The vertical vibration effect is transmitted to the rod 1, which in turn drives the shock isolation bearing 4 to move up and down. In the process of the shock isolation bearing 4 moving up and down, the steel ring 14 and the functional rubber ring 15 in series with the lead core provide vertical damping, and most of the vibration energy is consumed by the functional rubber ring 15. The horizontal vibration effect is also mostly consumed in the process of compressing the functional rubber ring 15 and the elastic rubber pad 6. The elastic rubber pad 6 consumes a part of the horizontal vibration effect on the one hand, and reduces the friction between the steel ring 14 and the bottom plate 5 on the other hand, preventing the shock isolation bearing from wearing and reducing the shock isolation effect. The connecting piece 3 plays a role in connecting the shock isolation bearing 4 and the support rod 9 through the damping support 10 on the one hand, and transmits the axial force and shear force received on the other hand, and transmits part of the force to the energy absorber 7 below. The energy absorber 7 can resist axial force and shear force, and when subjected to axial force, it can drive the piston 17 to reciprocate by the movement of the support rod 9, so that the viscous medium 16 in the cylinder expands or compresses, thereby consuming vibration energy and weakening vibration effect. The energy absorber 7 is connected to the damping support 10 at the bottom of the shock isolation trench through the support rod 9, and the support rod can rotate according to the deformation and stress condition, and is connected to the steel connecting piece through the support rod 9, and can also rotate according to the stress condition. The damping support 10 is used to buffer the amplification effect of the vibration load after the excavation of the shock isolation trench due to the sudden change of the local interface direction, and at the same time consumes the vibration effect conducted by the support rod 9. The waterproof cover plate 12 drains rainwater into the drainage ditch 11 on one side, preventing water accumulation in the shock isolation trench from affecting the safe use of the shock isolation trench. At the same time, the waterproof cover plate has a certain carrying capacity and can bear the weight of personnel walking, improving road safety and facilitating maintenance personnel. The foundation pit support cast-in-place pile 13 can ensure the safety of the foundation pit.

[0048] For the energy absorber 7, when the residual vibration effect on the upper part is conducted to the piston 17 through the connecting piece 3 and the support rod 9, the piston 17 will start to compress the viscous medium 16, and the damping will increase sharply after the viscous medium 16 is compressed, eliminating the vibration effect. After the vibration is eliminated, the piston 17 will slowly return to its original position. In addition, if the energy absorber is disturbed by out-of-plane vibration load, the end of the energy absorber can flexibly rotate through the damping support 10 to absorb vibration from all directions, while balancing the force on the energy absorber, achieving high-efficiency shock isolation.

[0049] In the application scenario of the embodiment, the wheel-rail impact frequency is about 10-50 Hz, the pile driver is about 15-40 Hz, the road roller is about 20-35 Hz, and the drilling machine is about 10-30 Hz. Therefore, the vibration frequency range is mainly concentrated in 10-50 Hz.

[0050] The functional rubber ring 15 and the steel ring 14 are arranged alternately, that is, the rubber ringn pcs, thickness is d , the area is S ; Steel ring ( n +1) pieces, thickness is D , the area is S , and are connected in series by a lead core, the lead core length L = (2 n +1) d , the cross-sectional area is A , where the shear modulus of natural rubber is G = 1MPa.

[0051] The natural frequency with damping satisfies the formula:

[0052] (1)

[0053] in, k is the total stiffness of the isolation bearing 4, m is the total mass of the vibration transmitting part of the seismic isolation support 4, ξ is the damping ratio. To ensure that the system does not resonate, the external frequency f Must be far away from the natural frequency of the system f n , usually need to meet the following requirements:

[0054] (2)

[0055] In formula (2) γ is the safety factor (usually 0.2~0.3), which means that the recommended operating frequency should deviate from the natural frequency by at least ±20%~30%. Assuming the safety factor is 0.2, the relationship is:

[0056] or (3)

[0057] Because the functional rubber ring 15 plays a major role in the energy dissipation process of the seismic isolation bearing 4, the steel ring 14 has extremely high rigidity and does not undergo significant deformation. It does not directly provide elastic stiffness, but it plays a key structural constraint role, ensuring that the functional rubber ring 15 operates in shear mode to avoid uneven deformation. The lead core mainly undergoes shear deformation and provides plastic damping. To simplify the calculation, the parameters of the functional rubber ring 15 are used as a benchmark, considering the main elastic stiffness contribution of the functional rubber ring 15, and the total mass is converted into an equivalent thickness:

[0058] (4)

[0059] in m is the total mass of the isolation support 4, ρ is the density of the functional rubber ring 15, Sis the area of the functional rubber ring 15. Since the lead core, the functional rubber ring 15 and the steel ring 14 are in close contact, the small gap between the lead core and the functional rubber ring 15 is ignored, and the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α may be expressed as:

[0060] (5)

[0061] wherein, R is the radius of the functional rubber ring, r is the radius of the lead core. Similarly, the ratio of the thickness of the steel ring 14 to the thickness of the functional rubber ring 15 is β is:

[0062] (6)

[0063] The final equivalent formula (1) can be converted to:

[0064] (7)

[0065] wherein, n is the number of functional rubber rings 15, ρ is the density of the functional rubber ring 15, H is the mass equivalent thickness of the seismic isolation bearing 4, d is the thickness of the functional rubber ring 15, ξ is the damping ratio, G is the shear modulus.

[0066] In addition, considering the transmission effect of the device on the vibration, the vibration transmission rate formula is:

[0067] (8)

[0068] wherein, T is the vibration transmission rate, ξ is the damping ratio, λ is the frequency ratio, and the expression is λ = f / f n , f is the external frequency, f n is the frequency of the seismic isolation system, and according to formula (8), theoretically λ > when the device has a seismic isolation effect. Therefore, the design frequency also needs to satisfy:

[0069] (9)

[0070] wherein, f nmaxTo avoid the maximum natural frequency of the possible resonance zone when the safety factor is 0.2, from equation (3), to ensure a certain safety range, f nmax The following conditions need to be met:

[0071] (10)

[0072] Therefore, combining equation (9) and equation (10), we can calculate f n The range is as follows:

[0073] (11)

[0074] After calculation, in order to avoid the resonance region and take full advantage of the isolation effect of the isolation trench, the designed natural frequency needs to meet f n <5.8 Hz. From equation (8), we can see that f n The smaller the vibration transmission rate is, the lower the vibration transmission rate is.

[0075] In this embodiment, the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α = 0.19, the ratio of the thickness of the steel ring 14 to the functional rubber ring 15 is β = 1, and the number of functional rubber rings n The isolation rate results under different external load frequencies are shown in Table 1.

[0076] Table 1 Isolation rate results when α = 0.19, β = 1

[0077]

[0078] Example 2

[0079] Compared with Example 1, in this embodiment, the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α = 0.19, the ratio of the thickness of the steel ring 14 to the functional rubber ring 15 is β = 0.5, and the number of functional rubber rings n The isolation rate results under different external load frequencies are shown in Table 2.

[0080] Table 2 Isolation rate results when α = 0.19, β = 0.5

[0081]

[0082] Example 3

[0083] Compared with the previous embodiments, in this embodiment, the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α = 0.19, the ratio of the thickness of the steel ring 14 to the functional rubber ring 15 is β = 2, and the number of functional rubber rings n The isolation rate results under different external load frequencies are shown in Table 3.

[0084] Table 3 Isolation rate results for α = 0.19, β = 2

[0085]

[0086] Example 4

[0087] In this example, the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α = 0.125, the ratio of the thickness of the steel ring 14 to the functional rubber ring 15 is β = 1, and the number of functional rubber rings is 2, as compared to the previous examples. n The isolation rate results for different external load frequencies are shown in Table 4.

[0088] Table 4 Isolation rate results for α = 0.125, β = 1

[0089]

[0090] Example 5

[0091] In this example, the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α = 0.125, the ratio of the thickness of the steel ring 14 to the functional rubber ring 15 is β = 0.5, and the number of functional rubber rings is 2, as compared to the previous examples. n The isolation rate results for different external load frequencies are shown in Table 5.

[0092] Table 5 Isolation rate results for α = 0.125, β = 0.5

[0093]

[0094] Example 6

[0095] In this example, the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α = 0.125, the ratio of the thickness of the steel ring 14 to the functional rubber ring 15 is β = 2, and the number of functional rubber rings is 2, as compared to the previous examples. n The isolation rate results for different external load frequencies are shown in Table 6.

[0096] Table 6 Isolation rate results for α = 0.125, β = 2

[0097]

[0098] Based on the isolation rate results of the above examples, it can be seen that the system, in which the ratio of the cross-sectional area of the lead core to the area of the functional rubber ring 15 is α = 0.125, the ratio of the thickness of the steel ring 14 to the functional rubber ring 15 is β = 2, and the number of functional rubber rings is 2, has the best isolation effect. nThe highest isolation rate of low-frequency impact load can reach 92.4%, the isolation rate of medium-frequency impact load can reach 97.2%, and the isolation rate of high-frequency vibration impact load can reach 98.6% in the optimal design interval 20-30 of the function rubber ring, and the control effect of parameter change on low-frequency vibration is significantly higher than that on high-frequency vibration. In addition, increasing the number, thickness and area of the functional rubber ring can reduce the natural frequency, and the thickness of the single rubber ring has the most significant effect on the isolation efficiency, followed by the number of functional rubber rings, and the area of the rubber ring has no obvious effect on the isolation efficiency, which is specifically shown as follows:

[0099] When the thickness of the steel ring and the functional rubber ring is equal, the isolation effect is obviously weaker than that when the thickness is not equal under the condition that other parameters remain unchanged, increasing the thickness of the rubber ring and the thickness of the steel ring can enhance the isolation effect, and increasing the thickness of the rubber ring is more beneficial to the isolation effect than increasing the thickness of the steel ring. Increasing the thickness of the rubber ring by 1cm can improve the isolation effect of low-frequency vibration load by nearly 40%, while increasing the thickness of the steel ring by 1cm can only improve the isolation effect of low-frequency vibration load by nearly 12%, so under the condition of meeting the requirements of engineering practice, the thickness of the rubber ring should be increased preferentially.

[0100] When other parameters remain unchanged, the optimal design interval of the rubber ring is 20-30, and the isolation efficiency for low-frequency vibration can be increased by 31%, that is, the isolation efficiency can be improved by 3.1% on average for each increase of one rubber ring and one steel ring.

[0101] Increasing the area of the rubber ring and the steel ring can improve the isolation efficiency. The area of the rubber ring and the steel ring can be controlled by controlling the ratio of the radius of the rubber ring to the radius of the lead core inside. The calculation results show that when the radius of the lead core inside is constant, increasing the radius of the rubber ring by 10cm can improve the isolation efficiency by 2%-3%.

[0102] In summary, the application avoids the resonance region and considers improving the isolation efficiency. Considering economic benefits and construction workload, the design parameters in the isolation trench system considered by the application are as follows: the radius of the functional rubber ring is 50cm, the radius of the steel ring is 50cm, the radius of the lead core is 10cm, the thickness of the functional rubber ring is 2cm, the number of the functional rubber ring is 25, the thickness of the steel ring is 1cm, and the number of the steel ring is 26. The isolation rates of low-frequency, medium-frequency and high-frequency trains and foundation pit vibration can reach 90.2%, 96.6% and 98.3% respectively, which realizes the mutual influence between the existing railway and the adjacent excavated foundation pit, and ensures the safety of railway operation and foundation pit excavation.

[0103] In addition, in actual engineering applications, when different frequencies need to be adjusted, the thickness of the functional rubber ring and the steel ring should be increased, and the ratio of the thickness of the functional rubber ring to the thickness of the steel ring should be increased to increase the isolation efficiency. On this basis, the number of functional rubber rings can be increased to further improve the isolation effect.

[0104] Compared with the prior art, the present application has the following beneficial effects:

[0105] (1) Good isolation effect. The existing scheme connects the two sides of the isolation trench through a rigid support rod, which transmits all vibration effects from one end of the rod to the other end, resulting in low isolation rate. The present application uses a composite isolation device, which combines the use of isolation bearings, energy absorbers, damping bearings and other energy dissipation elements, and combines the use of rigid support rods and isolation bearings. Most of the vibrations are consumed in the cooperation of the support rod and the isolation bearing, which not only ensures the isolation efficiency, but also ensures the stability of the isolation trench.

[0106] (2) Diversified isolation form. The structure adopted in the present application not only eliminates vibration effects, but also can well bear axial force and shear force. A variety of materials and different isolation forms are used in the isolation trench. The combination of different materials is beneficial to the complementary performance of the materials, such as the functional rubber ring which relies on its strong elastic deformation ability to mainly play the role of frequency adjustment and energy dissipation, and the steel ring which relies on its high strength to play the role of restraining the functional rubber ring to ensure the normal work of the structure.

[0107] (3) Multi-parameter collaborative design. The performance of the rigid support rod is difficult to quantify, which makes the parameter design and control of the existing isolation trench system difficult. The present application can cope with different frequency train vibration loads and the vibration effects generated by various construction equipment by adjusting the area, number, thickness of the functional rubber ring and the thickness ratio of the steel ring. It can also adjust the parameters according to the material supply situation and the width design requirements of the isolation trench. For example, if there is a lack of functional rubber rings with high thickness, the same design effect can be achieved by increasing the number of rubber rings, which has high flexibility. In addition, subsequent intelligent design can analyze the best parameter ratio scheme according to numerical calculation, and realize high-precision control of vibration.

[0108] (4) Good adaptation to soil displacement. The traditional isolation measures with filling materials often lose their shock absorption effect after the soil deforms to a certain extent. The device has good deformation characteristics. The steel rod has good toughness, the isolation bearing and the energy absorber have large deformation capacity, and the steel connecting piece can adjust the stress of each component. Even if the soil displaces partially, the structure can still support the soil to avoid large deformation.

[0109] (5) The construction is convenient, and the application range is wide. The isolation trench of the existing invention is too dependent on the whole structure. Once a component fails, for example, the cover plate of the isolation trench is stuck or the damper fails due to fatigue, the work of the isolation trench will be greatly affected. If construction maintenance is carried out, the whole structure may need to be removed and reinstalled. Each isolation unit and isolation component in the isolation trench of the present application can be independently disassembled, facilitating replacement and maintenance, and the structure can still play a part of the isolation function during the replacement process, ensuring the isolation effect of the isolation trench. The drainage on both sides of the isolation trench can timely drain away rainwater, and can be used under different weather conditions. By regularly replacing the isolation support and the energy absorber, failure of the isolation support and the energy absorber due to long-term load and fatigue can be avoided.

[0110] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas, characterized in that: The invention comprises a seismic isolation device provided in a seismic isolation trench between a railway and an adjacent foundation pit, the seismic isolation device comprising: Two isolation arms connected by a connecting member (3) are respectively abutted on two opposite supporting piles (8) of the isolation trench, each isolation arm comprising an isolation support (4), an elastic rubber pad (6), a rod (1) and a bottom plate (5), wherein the isolation support (4) comprises a lead core, steel rings (14) and functional rubber rings (15) alternately arranged on the lead core, and the elastic rubber pad (6) is sleeved on both ends of the lead core and abuts against the steel ring (14) at the end of the isolation support (4); A pair of energy dissipators (7), one end of which is movably connected to the connecting member (3), and the other end of which is connected to the damping support (10) at the contact point between the supporting pile row (8) and the bottom surface of the seismic isolation trench, One end of the seismic isolation support (4) bears the vibration force transmitted by the rod (1), consumes the vibration energy through up and down displacement, and suppresses and isolates the vertical vibration. The connecting member (3) is used to transmit the horizontal axial force and the vertical shear force, and disperses the vibration energy to the energy dissipator (7). The elastic rubber pad (6) is used to consume the horizontal vibration energy through buffering, and reduce the wear of the steel ring (14) at the end of the seismic isolation support (4). The energy dissipator (7) is used to consume the energy in the vertical and horizontal directions, resist the axial force and the shear force, and play a supporting role. The natural frequency of the seismic isolation device is less than 5.8 Hz, the radius of the functional rubber ring (15) is 50 cm, the radius of the steel ring (14) is 50 cm, the radius of the lead core is 10 cm, the thickness of the functional rubber ring (15) is 2 cm, the number is 25, the thickness of the steel ring (14) is 1 cm, the number is 26.

2. The seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas according to claim 1 is characterized in that: The length of the seismic isolation trench is greater than the length of the long side of the excavated foundation pit, and the depth is greater than the depth of the excavated foundation pit. The strength and rigidity of the foundation pit support cast-in-place piles (13) are both higher than those of the seismic isolation trench support piles (8).

3. The seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas according to claim 1 is characterized in that: A plurality of pairs of support piles (8) are evenly spaced in the seismic isolation trench along the length direction of the seismic isolation trench, and each pair of support piles (8) is provided with a seismic isolation device.

4. The seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas according to claim 1 is characterized in that: Any of the energy dissipators (7) includes a rotatable support rod (9), a cylinder sealed with a viscous medium (16), and a piston (17) matched with the cylinder. The other end of the support rod (9) is connected to the damping support (10). When the energy dissipator (7) is subjected to an axial force, the movement of the support rod (9) pushes the piston (17) to reciprocate, causing the viscous medium (16) in the cylinder to expand or compress, consume vibration energy, and suppress vibration effects. The damping support (10) is used to suppress the amplification effect of the vibration load caused by the sudden change in the direction of the local interface after the excavation of the seismic isolation trench.

5. The seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas according to claim 1 is characterized in that: Also includes: A waterproof cover plate (12) is arranged above two opposing support piles (8) of the seismic isolation ditch to seal the seismic isolation ditch. The bottom of the drainage ditch (11) is coated with a waterproof material.

6. The seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas according to claim 1 is characterized in that: The base plate (5) is connected to the supporting piles (8) via bolt fasteners (2).

7. The seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas according to claim 1 is characterized in that: The rod (1) is a hollow circular alloy steel rod, and the connecting piece (3) is a steel connecting piece.

8. The seismic isolation trench system for alleviating the impact of existing railways on foundation pit excavation in adjacent areas according to claim 1 is characterized in that: The two seismic isolation arms are symmetrically arranged with the connecting member (3) as the center.

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