Longitudinal loading device and method for shield tunnel longitudinal deformation test

Abstract

The invention discloses a longitudinal loading device and method for a shield tunnel longitudinal deformation test, and the method comprises the steps: driving a first support and a second support to drive a first axial loading part and a second axial loading part to move relatively through an axial load loading mechanism, so as to apply an axial load to a segment sample group at two axial ends; and meanwhile, the bending moment loading mechanism drives the first axial loading piece and the second axial loading piece to rotate so as to apply bending moment to the segment sample group at the two axial ends, so that the segment sample group can be subjected to an equivalent bending rigidity test under the action of the applied axial load and bending moment. In addition, a vertical load loading mechanism capable of applying a vertical load to the segment sample is also arranged, so that the segment sample group can be subjected to an equivalent shear stiffness test under the action of the applied axial load and vertical load. Therefore, the method has good universality, so that the test efficiency can be improved, and the cost can be remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of tunnel deformation testing technology, and in particular to a longitudinal loading device and method for longitudinal deformation testing of shield tunnels. Background Technology

[0002] During construction and operation, shield tunnels are subjected to various loads, which can cause longitudinal deformation of the tunnel. From the perspective of load-structure method, these loads can be categorized into three main types: bending moment, axial force, and vertical load.

[0003] During construction, the main loads come from the thrust of the tunnel boring machine (TBM) jacks and the pressure of synchronous grouting. Uneven distribution of the jack thrust not only generates axial pressure but may also induce additional bending moments; while the synchronous grouting pressure can be simplified as an upward buoyancy load. During operation, the tunnel may be affected by surrounding construction (such as foundation pit excavation and adjacent TBM construction) and ground overloading, which can be converted into downward loads acting on the tunnel structure.

[0004] The equivalent continuous beam model is an important method for studying the longitudinal deformation response of tunnel-soil interaction under the aforementioned complex conditions. The key parameters in the mechanical model, equivalent bending stiffness and equivalent shear stiffness, are crucial indicators characterizing the bending and shear resistance of shield tunnels. Through model tests, the equivalent bending stiffness of shield tunnels under bending moment and axial force, as well as the equivalent shear stiffness under shear force and axial force, can be calibrated. Furthermore, model tests are also a key means of studying the mechanical response of tunnel-soil interaction under complex conditions.

[0005] However, both types of tests currently require the design of dedicated testing equipment, which not only increases testing costs but also reduces testing efficiency. Furthermore, both types of tests are conducted without soil constraints; therefore, they can only simulate and measure key mechanical performance parameters of the tunnel structure itself, but cannot simulate or explore the overall mechanical response under the combined action of the tunnel structure and soil.

[0006] Given that the loads borne by shield tunnels during construction and operation can be categorized into three main types—bending moment, axial force, and vertical load—a universal testing apparatus can be designed to simultaneously meet the needs of longitudinal mechanical performance testing and tunnel-soil interaction mechanical response testing of shield tunnels. This will improve testing efficiency and significantly reduce costs, providing an efficient and economical solution for the mechanical research of shield tunnels. Summary of the Invention

[0007] The main objective of this invention is to propose a longitudinal loading device and method for longitudinal deformation testing of shield tunnels, aiming to improve the versatility of the longitudinal loading device, increase testing efficiency, and reduce testing costs.

[0008] To achieve the above objectives, the present invention provides a longitudinal loading device for longitudinal deformation testing of shield tunnels, comprising:

[0009] A first and a second support that are horizontally positioned relative to each other and can move relative to each other;

[0010] A first axial loading member rotatably mounted on a first support and a second axial loading member rotatably mounted on a second support, the first axial loading member and the second axial loading member being opposite to each other, are used to press against the axial ends of the tube segment sample group.

[0011] An axial load loading mechanism is used to drive the first support and the second support to move the first axial loading member and the second axial loading member relative to each other, so that the first axial loading member and the second axial loading member apply axial load to the tube segment sample group at both ends of the axial direction.

[0012] A bending moment loading mechanism is used to drive a first axial loading member and a second axial loading member to rotate, so that the first axial loading member and the second axial loading member apply a bending moment to the segment sample assembly from both axial ends; and

[0013] The vertical load loading mechanism is used to apply vertical loads to the segment sample group.

[0014] To achieve the above objectives, another aspect of the present invention proposes a longitudinal loading method for longitudinal deformation testing of shield tunnels, comprising the following steps:

[0015] S1. According to the test requirements, select a segment sample group consisting of a predetermined number and length of segment samples, and drive the first support and the second support to move relative to each other so that the first axial loading member and the second axial loading member abut against the segment sample group at both ends of the axial direction.

[0016] S2. According to the test requirements, drive the first and second supports to rotate to apply bending moments to the segment specimen group from both axial ends, and / or apply vertical loads to the predetermined segment specimens through the vertical load loading mechanism.

[0017] The present invention rotatably mounts a first axial loading member and a second axial loading member onto a first support and a second support, respectively. An axial load loading mechanism drives the first and second supports to move the first and second axial loading members relative to each other. This adapts to the testing requirements of segment specimen groups of different lengths, applying axial loads to the segment specimen group at both axial ends. Simultaneously, a bending moment loading mechanism drives the first and second axial loading members to rotate, applying bending moments to the segment specimen group at both axial ends. This allows the segment specimen group to undergo equivalent bending stiffness testing under the axial load and bending moment applied by the present invention. Furthermore, the present invention includes a vertical load loading mechanism that applies vertical loads to the segment specimens, allowing the segment specimen group to undergo equivalent shear stiffness testing under the axial load and vertical load applied by the present invention. Therefore, the present invention can perform equivalent bending stiffness or equivalent shear stiffness testing on the segment specimen group individually, or simultaneously, depending on the testing requirements. Instead of requiring the design of dedicated longitudinal loading devices as in existing technologies, the present invention demonstrates good versatility, thereby improving testing efficiency and significantly reducing costs. Attached Figure Description

[0018] Figure 1 This is a three-dimensional schematic diagram of the present invention from one angle;

[0019] Figure 2 This is a three-dimensional schematic diagram of the present invention from another angle;

[0020] Figure 3 This is a three-dimensional schematic diagram of a portion of the structure of the present invention (with the vertical load loading mechanism and the third pushing member removed).

[0021] Figure 4 for Figure 3 Enlarged detail of Part A;

[0022] Figure 5 This is a schematic diagram showing the coordination between the vertical load loading mechanism and the soil layer simulation mechanism;

[0023] Figure 6 This is an assembly diagram of the bending moment loading mechanism and the first axial loading component (or the second axial loading component);

[0024] Figure 7 This is a schematic diagram illustrating the principle of the double-ring bending test for this invention.

[0025] Figure 8 This is a schematic diagram illustrating the principle of the three-ring shear test for this invention.

[0026] Figure 9 This is a schematic diagram illustrating the principle of the three-point bending test for this invention.

[0027] Figure 10 This is a schematic diagram illustrating the principle of the four-point bending test for this invention.

[0028] Figure 11 This is a schematic diagram illustrating the principle of the shield tunnel response test under the combined action of uneven jack load and synchronous grouting according to the present invention.

[0029] Figure 12 This is a schematic diagram illustrating the principle of the shield tunnel response test for the underlying soil voiding of the present invention.

[0030] Figure 13 This is a schematic diagram illustrating the principle of the shield tunnel response test for local segment reinforcement according to the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, top, bottom, inside, outside, vertical, horizontal, longitudinal, counterclockwise, clockwise, circumferential, radial, axial, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0033] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0034] One aspect of this invention is a longitudinal loading device for longitudinal deformation testing of shield tunnels.

[0035] In embodiments of the present invention, such as Figures 1 to 13As shown, the longitudinal loading device for the longitudinal deformation test of a shield tunnel includes a first support 1, a second support 2, a first axial loading member 3, a second axial loading member 4, an axial load loading mechanism 5, a bending moment loading mechanism 6, and a vertical load loading mechanism 7. The first support 1 and the second support 2 are horizontally opposite each other and can move relative to each other. The first axial loading member 3 is rotatably mounted on the first support 1, and the second axial loading member 4 is rotatably mounted on the second support 2, with the first axial loading member 3 and the second axial loading member 4 facing each other, used to press against the axial ends of the segment sample group (not shown). The axial load loading mechanism 5 is used to drive the first support 1 and the second support 2 to move the first axial loading member 3 and the second axial loading member 4 relative to each other, adapting to the testing requirements of segment sample groups of different lengths. It drives the first axial loading member 3 and the second axial loading member 4 to apply axial loads to the segment sample group at both axial ends, and after the test, it drives the first support 1 and the second support 2 to separate the first axial loading member 3 and the second axial loading member 4 from the axial ends of the segment sample group. The bending moment loading mechanism 6 drives the first support 1 and the second support 2 to rotate, so that the first axial loading member 3 and the second axial loading member 4 apply bending moments to the segment specimen group from both axial ends, thereby enabling the segment specimen group to undergo an equivalent bending stiffness test under the axial load and bending moment applied by the present invention. The vertical load loading mechanism 7 applies a vertical load to the segment specimen group, enabling the segment specimen group to undergo an equivalent shear stiffness test under the axial load and vertical load applied by the present invention. This allows the present invention to perform equivalent bending stiffness or equivalent shear stiffness tests on the segment specimen group individually, or simultaneously, according to test requirements, without requiring the separate design of dedicated longitudinal loading devices as in the prior art. Therefore, the technical solution of the present invention has good versatility, thereby improving test efficiency and significantly reducing costs.

[0036] Understandably, the segment sample group consists of multiple axially distributed annular segment samples (not shown). The multiple segment samples are spliced ​​together by bolts to form a discontinuous structure. The specific splicing method is prior art and well known to those skilled in the art, and will not be described in detail here.

[0037] In some embodiments of the present invention, the first support 1 and the second support 2 are slidably mounted on the support surface 101. The support surface 101 can be the ground, a tabletop, a rigid bracket, a base plate, or the surface of a support platform 100. There are various ways in which the first support 1 and the second support 2 are slidably mounted on the support surface 101. For example, the support surface 101 is provided with a horizontal first guide rail 102, and the bottom of the first support 1 and / or the second support 2 is provided with a first slider 103 that slidably engages with the first guide rail 102. The first support 1 and / or the second support 2 can be slidably mounted on the support surface 101 relative to each other through the engagement of the first slider 103 and the first guide rail 102, and can reciprocate linearly along the first guide rail 102 under the drive of the axial load loading mechanism 5, so as to drive the first axial loading member 3 and the second axial loading member 4 to move relative to each other, thereby causing the first axial loading member 3 and the second axial loading member 4 to abut or separate from the tube sample group at both ends in the axial direction.

[0038] In some embodiments of the present invention, the axial load loading mechanism 5 is a pneumatic cylinder or a hydraulic cylinder, and may be equipped with a pressure gauge (not shown) to understand the magnitude of the axial load exerted by the pneumatic cylinder or hydraulic cylinder on both ends of the tube sample group through the first axial loading member 3 and the second axial loading member 4.

[0039] The cylinder or hydraulic cylinder is fixed to the support surface 101 directly or through the mounting structure. For example, the support surface 101 is provided with a longitudinal reaction frame 104 at the position corresponding to the first support 1 and / or the second support 2. The cylinder body of the cylinder or hydraulic cylinder is fixed to the longitudinal reaction frame 104, and the piston rod is directly or through an intermediate part connected to the first support 1 or the second support 2.

[0040] Understandably, the shape and structure of the first support 1 and the second support 2 can be implemented in various ways. For example, the first support 1 and the second support 2 are gantry structures. The bottom of the two side columns of the gantry structure are provided with first sliders 103, and the first guide rails 102 are correspondingly arranged with the first sliders 103.

[0041] To ensure uniform force distribution on the first support 1 and / or the second support 2, a first pushing member 51 is connected to the end of the piston rod of the cylinder or hydraulic cylinder. The first pushing member 51 is connected to the first support 1 or the second support 2. The shape and structure of the first pushing member 51 can have various implementations. In a preferred embodiment, the first pushing member 51 is a horizontally arranged U-shaped frame structure, including a base arm 511 and side arms 512 located at both ends of the base arm 511. The piston rod of the cylinder or hydraulic cylinder is connected to the base arm 511, and the two side arms 512 are connected to the first support 1 or the second support 2. When the first support 1 and the second support 2 form a gantry structure, the two side arms 512 are respectively connected to the two side columns of the first support 1 or the second support 2.

[0042] In some embodiments of the present invention, the shape and structure of the first axial loading member 3 and the second axial loading member 4 have various forms. In a preferred embodiment, the first axial loading member 3 and the second axial loading member 4 are annular, both vertically arranged, and the side of the first axial loading member 3 and the second axial loading member 4 facing the segment sample group cooperates with the segment sample group. Specifically, the side of the first axial loading member 3 and the second axial loading member 4 facing the segment sample group is provided with annular grooves for partial insertion of the ends of the segment sample group to position the two ends of the segment sample group and enable the first axial loading member 3 and the second axial loading member 4 to apply axial loads and bending moments to the axial ends of the segment sample group during the test.

[0043] In some embodiments of the present invention, first rotating shafts 32 and 42 extend outward from the horizontal sides of the first axial loading member 3 and the second axial loading member 4, respectively. The first rotating shafts 32 and 42 are rotatably mounted on the first support 1 and the second support 2. The axes of the first rotating shafts 32 and 42 coincide with the axis of the segment sample. When the first axial loading member 3 and the second axial loading member 4 rotate around the axis of the first rotating shafts 32 and 42 under the drive of the bending moment loading mechanism 6, a bending moment can be applied to the segment sample group at both axial ends. When the first axial loading member 3 and the second axial loading member 4 rotate around the axis of the first rotating shafts 32 and 42 toward the axial center of the segment sample group (at this time, the distance between the upper ends of the first axial loading member 3 and the second axial loading member 4 decreases), a positive bending moment is generated on the segment sample group; when the first axial loading member 3 and the second axial loading member 4 rotate around the first rotating shafts 32 and 42 toward the axial center of the segment sample group (at this time, the distance between the upper ends of the first axial loading member 3 and the second axial loading member 4 increases), a negative bending moment is generated on the segment sample group.

[0044] Specifically, the first rotating shafts 32 and 42 extending outward from the horizontal sides of the first axial loading member 3 and the first rotating shafts 32 and 42 extending outward from the horizontal sides of the second axial loading member 4 can be either integral structures or split structures. When they are integral structures, the first rotating shafts 32 and 42 horizontally penetrate the first axial loading member 3 and the second axial loading member 4, respectively.

[0045] When the first rotating shafts 32 and 42 are of a split structure, they are symmetrically arranged on the horizontal sides of the first axial loading member 3 and the second axial loading member 4, respectively. In this embodiment, to facilitate the installation of the first rotating shafts 32 and 42 and to improve the connection strength between the first rotating shafts 32 and 42 and the first axial loading member 3 and the second axial loading member 4, the horizontal sides of the first axial loading member 3 and the second axial loading member 4 are provided with a cross-section perpendicular to their diameter, and the first rotating shafts 32 and 42 are located at the cross-section.

[0046] Furthermore, the first support 1 and the second support 2 are respectively provided with bearing seats 200 at positions corresponding to the first rotating shafts 32 and 42. The bearing seats 200 are fixed with bearings (not shown), and the first rotating shafts 32 and 42 are movably mounted on the bearings to ensure smooth rotation of the first rotating shafts 32 and 42.

[0047] In some embodiments of the present invention, both the first axial loading member 3 and the second axial loading member 4 are connected to a first swing arm 300. One end of the first swing arm 300 is connected to a bending moment loading mechanism 6, and the bending moment loading mechanism 6 drives the first axial loading member 3 and the second axial loading member 4 to swing through the first swing arm 300. It is understood that the shape and structure of the first swing arm can be implemented in various ways, such as U-shaped, circular, straight rod-shaped, or triangular structures. Exemplarily, the first swing arm 300 consists of two support arms 301, with one end of the two support arms 301 connected to form an acute angle. The connected end of the two support arms 301 is connected to the bending moment loading mechanism 6, and the other ends of the two support arms 301 are respectively connected to the ends of the first axial loading member 3 and the second axial loading member 4 facing away from the tube sample assembly.

[0048] In some embodiments of the present invention, the bending moment loading mechanism 6 is mounted on the first support 1 and the second support 2. The bending moment loading mechanism 6 can be a pneumatic cylinder or a hydraulic cylinder, and can be equipped with a pressure gauge to measure the bending moment exerted by the pneumatic or hydraulic cylinder on both axial ends of the segment sample group through the first axial loading member 3 and the second axial loading member 4. Specifically, when the bending moment loading mechanism 6 is a pneumatic or hydraulic cylinder, the cylinder body of the pneumatic or hydraulic cylinder is fixedly mounted on the first support 1 and the second support 2, respectively, and the piston rod is connected to the end of the first swing arm 300 facing away from the segment sample group. Preferably, the cylinder body of the pneumatic or hydraulic cylinder is fixedly mounted on the first support 1 and the second support 2 at a position corresponding to the first swing arm 300 above the segment sample group.

[0049] Furthermore, a support member 302 is fixedly provided at the lower end of the first swing arm 300, and the bottom surfaces of the first axial loading member 3 and the second axial loading member 4 are in contact with or connected to the support member 302 to generate an upward supporting force on the first axial loading member 3 and the second axial loading member 4.

[0050] In some embodiments of the present invention, the vertical load loading mechanism 7 includes a vertical reaction frame 71, a vertical drive mechanism 72 mounted on the vertical reaction frame 71, and a second pusher 73 mounted on the drive end of the vertical drive mechanism 72. The second pusher 73 can move up and down under the drive of the vertical drive mechanism 72. When it moves downward and presses against the tube sample, it can apply a vertical load to the corresponding tube sample.

[0051] The vertical reaction frame 71 can be implemented in various ways, such as a gantry structure or a cantilever beam structure. As shown in the figure, the cantilever beam structure includes a first column 711 and a first cantilever 712. The first column 711 is fixed on the support surface 101, and the first cantilever 712 extends above the tube segment sample group. The vertical drive mechanism 72 is directly or through the support structure installed on the first cantilever 712.

[0052] In some embodiments of the present invention, the cantilever beam structure is an integral structure or a plurality of spaced-apart split structures. Preferably, it is a split structure, in which the plurality of cantilever beam structures are spaced apart along the axial direction of the segment sample group, and the first cantilever 712 of the plurality of cantilever beam structures are connected together by a first longitudinal beam 713 at a position corresponding to the upper part of the segment sample group, and the vertical drive mechanism 72 is disposed on the first longitudinal beam 713.

[0053] Specifically, the vertical drive mechanism 72 includes a third cylinder or a third hydraulic cylinder arranged longitudinally at intervals. The cylinder body of the third cylinder or the third hydraulic cylinder is fixed to the first longitudinal beam 713, and the piston rod is connected to the second pushing member 73. The number and arrangement of the third cylinder or the third hydraulic cylinder and the second pushing member 73 are determined according to the test requirements, and the number and position of the second pushing member 73 correspond one-to-one with the number and position of the third cylinder or the third hydraulic cylinder. Each third cylinder or the third hydraulic cylinder can be controlled individually or synchronously according to the test requirements. The control method can be automatic or manual. In manual mode, the operator can adjust the pressure using a manual digital display pressure regulating valve, thereby driving the second pushing member 73 to apply the required pressure to the corresponding tube sample according to the test requirements.

[0054] Furthermore, the first column 711 is fixedly provided with a second cantilever 714 located below the first cantilever 712, and the first longitudinal beam 713 is fixedly connected to the first suspension 715 at both ends. The first suspension 715 is simultaneously fixedly connected to the first cantilever 712 and the second cantilever 714 at corresponding positions to improve the structural strength of the first cantilever 712, the second cantilever 714, and the first longitudinal beam 713, so as to better support the vertical drive mechanism 72. Specifically, the first suspension 715 is portal-shaped, and a second longitudinal beam 716 is connected between the suspended sides of the suspension to improve the structural strength of the first suspension 715.

[0055] In some embodiments of the present invention, the second pushing member 73 includes an upper adapter block 731 connected to the piston rod of a third cylinder or a third hydraulic cylinder and an upper liner 732 connected to the upper adapter block 731 at its upper end. The upper liner 732 is adapted to the upper part of the tube segment sample to apply a vertical load to the tube segment sample from above.

[0056] Furthermore, to improve the stability of the relative movement of the first support 1 and the second support 2, the present invention also includes a first guide rod 400. The first guide rod 400 is arranged longitudinally, with one end fixedly connected to the first support 1 or the second support 2, and the other end movably inserted into the second support 2 or the first support 1. When the first support 1 and the second support 2 move relative to each other, the second support 2 or the first support 1 slides along the first guide rod 400 to guide their relative movement. The number of first guide rods 400 is one, two, or more, preferably two. One end of the two first guide rods 400 is preferably fixed above the corresponding tube sample of the first support 1 or the second support 2. The cross-section of the first guide rod 400 can be circular, elliptical, or rectangular, preferably rectangular.

[0057] In the above embodiment, the second support 2 or the first support 1 is provided with a first guide hole (not shown) that is compatible with the first guide rod 400. The upper adapter block 731 is in the shape of an inverted mountain. One open end of the upper connecting block is connected to the upper pad 732, forming two horizontally spaced channels 7310. The other ends of the two first guide rods 400 pass through the two channels 7310 and are movably inserted into the first guide hole.

[0058] Furthermore, to simulate and explore the overall mechanical response under the combined action mechanism of the tunnel structure and soil layers, some embodiments of the present invention also include a soil layer simulation mechanism 8, used to simulate the constraint effect of the soil layer below the tunnel on the tunnel segments. In this embodiment, the soil layer simulation mechanism 8 includes a third pushing member 81 and an elastic loading mechanism 82 for applying an upward elastic force to the third pushing member 81.

[0059] In some embodiments of the present invention, the third pushing member 81 includes a lower adapter block 811 whose lower end is connected to the elastic loading mechanism 82 and a lower liner 812 whose lower end is connected to the lower adapter block 811. The lower liner 812 is adapted to the lower part of the tube segment sample to apply an upward elastic constraint force to the tube segment sample from below.

[0060] Generally, the outer circumferential surface of the tube segment specimen is a circular or elliptical arc surface. The lower surface of the upper liner 732 and the upper surface of the lower liner 812 are circular or elliptical surfaces that mate with the outer circumferential surface of the tube segment specimen, so that the upper liner 732 and the lower liner 812 can align with the tube segment specimen, allowing vertical loads and elastic forces to be uniformly transferred to the tube segment specimen. Furthermore, the upper liner 732 and the upper adapter block 731, as well as the lower liner 812 and the lower adapter block 811, are detachably connected, allowing for the replacement of the upper liner 732 and the lower liner 812 with appropriate fittings according to the cross-sectional shape of the tube segment specimen.

[0061] In some embodiments of the present invention, the number of elastic loading mechanisms 82 can be one or more. When there is one, all the third pushing members 81 are connected to the elastic loading mechanism 82.

[0062] When there are multiple elastic loading mechanisms 82, the number of elastic loading mechanisms 82 corresponds one-to-one with the number and position of the third pushing members 81, and each third pushing member 81 is connected to a corresponding elastic loading mechanism 82. In this embodiment, each elastic loading mechanism 82 includes at least two support rods 821 whose upper ends are connected to the third pushing member 81, a support plate 822 disposed at the lower ends of the at least two support rods 821, a second guide rod 823 fixed to the support surface 101, and a top spring 824 sleeved on the second guide rod 823. The second guide rod 823 is movably inserted into the support plate 822, and the upper end of the top spring 824 elastically abuts against the support plate 822 to apply an upward elastic force to the support plate 822, thereby causing the third pushing member 81 to apply an upward elastic constraint force to the tube sample. The third pushing member 81 is arranged along the axial direction (i.e., longitudinal direction) of the tube sample group, and the number and arrangement of the third pushing member 81 can be determined according to the test requirements.

[0063] Furthermore, it also includes a guide frame 825, on which the support rod 821 is movably inserted to guide the up-and-down movement of the support rod 821. Specifically, the guide frame 825 has an opening and a guide sleeve 826 that mates with the support rod 821 is installed. The support rod 821 is movably inserted into the guide sleeve 826 to make the up-and-down movement of the support rod 821 smoother.

[0064] Furthermore, the support surface 101 is provided with a pad 827, and the lower part of the second guide rod 823 is formed with external threads and screwed with a nut 828. The pad 827 is provided with corresponding screw holes (not shown). The second guide rod 823 is screwed onto the pad 827 through the cooperation of the external threads and screw holes. Before the test, the height of the second guide rod 823 can be adjusted by rotating it as needed. After the height is adjusted, the nut 828 is rotated to abut against the pad 827, thereby fixing the second guide rod 823.

[0065] Preferably, the upper end of the second guide rod 823 can extend to be close to, abut against, or detachably connected to the guide frame 825 to prevent the support plate 822 from coming off the second guide rod 823. The connection method can also improve the structural stability of the second guide rod 823 and ensure smooth up and down movement of the support plate 822.

[0066] Furthermore, the first support 1 and the second support 2 of the present invention are also provided with a vertical adjustment mechanism 9. The first axial loading member 3 and the second axial loading member 4 are respectively rotatably mounted on the vertical adjustment mechanism 9. The height of the first axial loading member 3 and the second axial loading member 4 can be adjusted by the vertical adjustment mechanism 9 to adapt to the different requirements of different tube sample diameters and / or different elastic stiffness of the top spring 824.

[0067] In some embodiments of the present invention, the vertical adjustment mechanism 9 includes a vertical guide rail 91 fixedly mounted on a first support 1 and a second support 2, a lifting seat 92 slidably mounted on the vertical guide rail 91 via a slider, and an adjustment mechanism 93 that drives the lifting seat 92 to move up and down along the vertical guide rail 91. The first rotating shafts 32 and 42 are rotatably mounted on the lifting seat 92 directly or via a bearing seat 200 with a bearing shaft. Before the experiment, according to the experimental requirements, the adjustment mechanism 93 drives the lifting seat 92 to move the first axial loading member 3 and the second axial loading member 4 along the vertical guide rail 91 to a predetermined height.

[0068] In some embodiments of the present invention, the adjustment mechanism 93 includes a lead screw 931 mounted on the first support 1 and the second support 2 respectively, a lead screw nut 932 fixed on the lifting seat 92 and cooperating with the lead screw 931, and a driving component for driving the lead screw 931 to rotate. The driving component can be an automatic driving component, such as a motor, a rotary cylinder or other rotary driving element, or a manual driving component, such as a crank handle 933. By driving the lead screw 931 to rotate through the driving component, the lead screw nut 932 can be driven to move the lifting seat 92 and the corresponding first axial loading component 3 and second axial loading component 4 up and down along the vertical guide rail 91, thereby adjusting the height of the first axial loading component 3 and the second axial loading component 4.

[0069] Furthermore, to prevent abnormal lifting of the lifting seat 92, a locking member (not shown) is included to lock the lifting mechanism onto the first support 1 and the second support 2. The locking member can be implemented in various ways, preferably with a bolt. The lifting seat 92 has threaded through holes facing the first support 1 and the second support 2 respectively. The bolt is screwed into the threaded through holes. When the bolt is tightened so that its rod end abuts against the first support 1 and the second support 2 respectively, the lifting seat 92 is locked onto the first support 1 and the second support 2. At this time, the vertical adjustment mechanism 9 cannot drive the lead screw 931 to rotate. Loosening the bolt releases the lock on the lifting seat 92. At this time, the vertical adjustment mechanism 9 can drive the lead screw 931 to rotate, causing the lifting seat 92 to move up and down, thereby achieving precise control of the height of the first axial loading member 3 and the second axial loading member 4.

[0070] After introducing the implementation method of the longitudinal loading device for shield tunnel longitudinal deformation testing according to the present invention, the implementation method of the test method using the longitudinal loading device for shield tunnel longitudinal deformation testing according to the present invention will be described next. The specific structure of the longitudinal loading device for shield tunnel longitudinal deformation testing is shown in the above embodiments, and repeated details will not be described again.

[0071] In this embodiment of the invention, the longitudinal loading method for longitudinal deformation testing of shield tunnels includes the following steps:

[0072] S1. According to the test requirements, a segment sample group consisting of a predetermined number and length of segment samples is selected, and the first support 1 and the second support 2 are driven to move relative to each other to drive the first axial loading member 3 and the second axial loading member 4 to abut against the segment sample group. This can adapt to the test requirements of segment sample groups of different lengths. After the test, the first support 1 and the second support 2 are driven to drive the first axial loading member 3 and the second axial loading member 4 to separate from the axial ends of the segment sample group.

[0073] S2. According to the test requirements, drive the first support 1 and the second support 2 to rotate to apply bending moment to the segment specimen group from both ends of the axial direction, and / or apply vertical load to the predetermined segment specimen through the vertical load loading mechanism 7.

[0074] In this embodiment of the invention, when the axial load loading mechanism 5 drives the first support 1 and the second support 2 to apply axial loads to the segment specimen group at both axial ends, and the bending moment loading mechanism 6 drives the first axial load member 3 and the second axial load member 4 to rotate to apply bending moments to the segment specimen group at both axial ends, the segment specimen group can undergo an equivalent bending stiffness test under the axial load and bending moment applied by the invention. When the axial load loading mechanism 5 drives the first support 1 and the second support 2 to apply axial loads to the segment specimen group at both axial ends, and the vertical load loading mechanism 7 applies a vertical load downwards to the segment specimen, the segment specimen group can undergo an equivalent shear stiffness test under the axial load and vertical load applied by the invention. Furthermore, when the invention simultaneously applies the aforementioned axial load, bending moment, and vertical load to the segment specimen group, both the equivalent bending stiffness and equivalent shear stiffness tests can be performed simultaneously.

[0075] Furthermore, step S2 of this invention also includes applying an upward elastic constraint force to the tunnel segment sample through the soil layer simulation mechanism 8 to simulate the constraint effect of the soil layer below the tunnel on the tunnel segment. This allows the present invention to simulate and explore the overall mechanical response under the combined action mechanism of the tunnel structure and the soil layer.

[0076] Specifically, the simulation of the upward floating effect of synchronous grouting pressure on tunnel segments was conducted.

[0077] Based on the above embodiments, it can be seen that the present invention can simulate bending moment, axial load, vertical load, and soil layers. It can meet the loading requirements of two major categories of tests: one is the testing of the longitudinal mechanical properties of shield tunnels (excluding soil layers), and the other is the longitudinal deformation response test under the interaction between the tunnel and the soil layers (including soil layers).

[0078] The testing of the longitudinal mechanical properties of shield tunnels includes, but is not limited to, double-ring bending test (for measuring equivalent bending stiffness), triple-ring shear test (for measuring equivalent shear stiffness), three-point bending test (for verifying the accuracy of equivalent bending stiffness and equivalent shear stiffness tests), and four-point bending test.

[0079] Among them, the double-ring bending test, such as Figure 7 As shown, this working condition generally requires two segments of the tube sample. The tube sample is allowed to rotate, and bending moment and axial load are applied at the same time. Therefore, only two functional modules are needed: the axial load loading mechanism 5 and the bending moment loading mechanism 6. The distance between the first support 1 and the second support 2 along the guide rail can be adjusted first (approximately the length of two segments of the tube sample). After the tube sample is installed, axial load and bending moment are applied to the tube sample group consisting of two segments of the tube sample at both ends of the axial direction according to the test requirements.

[0080] Three-ring shear test as follows Figure 8 As shown, this working condition generally requires three segments of the tunnel segment specimen, with both vertical and axial loads applied simultaneously. Therefore, only two functional modules are needed: the axial load loading mechanism 5 and the vertical load loading mechanism 7. The vertical load loading mechanism 7 only requires the use of one pneumatic or hydraulic cylinder. The distance between the first support 1 and the second support 2 along the guide rail can be adjusted (approximately the length of three segments of the tunnel segment specimen). After the tunnel segment specimen is installed, according to the test requirements, axial loads are applied to the tunnel segment specimen group consisting of three segments at both ends along the axial direction, and vertical loads are applied to the tunnel segment ring located in the middle position above.

[0081] Three-point bending test, such as Figure 9 As shown, this working condition requires multiple tunnel segment specimens (the specific number can be set according to the test requirements, such as 35 rings). During the test, bending moment, axial load, and vertical load are applied simultaneously. Therefore, three functional modules are required: axial load loading mechanism 5, bending moment loading mechanism 6, and vertical load loading mechanism 7. The vertical load loading mechanism 7 only needs to call one cylinder or hydraulic cylinder. The distance between the first support 1 and the second support 2 along the guide rail can be adjusted first (for example, approximately the length of 35 tunnel segment specimens), and the above three loads can be applied after the tunnel segments are installed.

[0082] Four-point bending test as follows Figure 10As shown, the required functional modules and implementation process are similar to those of the three-point bending test. The only difference is that the vertical load requires the participation of two oil cylinders or hydraulic cylinders, which will not be elaborated here.

[0083] Compared to tests of bending and shear mechanical properties, tests of longitudinal deformation response under tunnel-soil interaction require not only the participation of axial load loading mechanism 5, variable-pitch loading mechanism, and / or vertical loading mechanism, but also soil simulation mechanism 8. Whether it's the combined effects of various construction loads during actual tunnel construction (e.g., uneven jack loads, synchronous grouting loads), or construction disturbances encountered during operation (e.g., foundation pit excavation, new tunnel excavation), soil voiding below, and subsequent local segment reinforcement measures, all these conditions can be summarized as load variations, subgrade coefficient variations, and segment ring stiffness variations in shield tunnel longitudinal deformation analysis. By adjusting the relevant loading mechanisms in the device of this invention according to the actual working conditions, the simulation capability of tunnel-soil interaction under these complex conditions can be achieved. Based on this, longitudinal deformation response tests under the interaction between the tunnel and the soil layer include, but are not limited to, shield tunnel response tests (load variability and subgrade coefficient variability) under the combined action of uneven jack load and synchronous grouting, shield tunnel response tests (load variability and subgrade coefficient variability) under the void of the underlying soil, and shield tunnel response tests with local segment reinforcement.

[0084] Among them, the shield tunnel response test under the combined action of uneven jack load and synchronous grouting is as follows: Figure 11 As shown, this working condition requires multiple tunnel segment samples (e.g., 35 tunnel segment samples) to apply bending moments and axially varying buoyancy forces. At the same time, the subgrade coefficient of the soil layer also varies axially. Therefore, only three functional modules are needed around the tunnel: bending moment loading mechanism 6, vertical load loading mechanism 7, and soil layer simulation mechanism 8. The changes in buoyancy forces and subgrade coefficients are adjusted by the magnitude of the load that can be applied by the vertical load loading mechanism 7 at different locations and the stiffness and number of top springs 824.

[0085] Response test of shield tunnel with soil void below (load variability and subgrade coefficient variability) as follows Figure 12As shown, under this working condition, multiple tunnel segment samples (e.g., 35 tunnel segment samples) are required to apply vertical loads. The vertical loads can come from disturbances such as foundation pit excavation, shield tunneling, and ground overloading in actual tunnel construction. There are relevant quantitative formulas for converting these into vertical loads, which will not be elaborated here. At the same time, the subgrade coefficient of the soil layer also changes along the axial direction. Therefore, only two functional modules are needed around the tunnel: the vertical load loading mechanism 7 and the soil layer simulation mechanism 8. The vertical load and the changes in the subgrade coefficient of different soil layers can be adjusted by the magnitude of the load applied by the vertical load loading mechanism 7 at different locations and the stiffness and number of top springs 824. The void area can be directly removed by removing the third pushing member 81 of the corresponding tunnel segment sample.

[0086] Local segment reinforcement shield tunnel response test, such as Figure 13 As shown, this working condition requires multiple tunnel segment samples (e.g., 35 tunnel segment samples), typically including some normal tunnel segment samples and some tunnel segment samples that have been reinforced after damage (reinforced tunnel segment samples) to apply vertical loads. In actual tunnel construction, vertical loads can come from disturbances such as foundation pit excavation, shield tunneling, and ground overload, all of which have relevant quantitative formulas for conversion into vertical loads, which will not be elaborated here. Therefore, only two functional modules are needed around the tunnel: the vertical load loading mechanism 7 and the soil layer simulation mechanism 8.

[0087] As can be seen from the above, the technical solution of the present invention has good versatility, thereby improving experimental efficiency and significantly reducing costs.

[0088] It should be noted that the present invention mainly provides a longitudinal loading device and method for longitudinal deformation testing of shield tunnels. During the longitudinal deformation test of shield tunnels, it is also necessary to arrange corresponding monitoring instruments and data acquisition and processing devices. The monitoring instruments and data acquisition and processing devices are all existing technologies and are well known to those skilled in the art. They are not the content to be protected by the present invention. The arrangement and working principle of the monitoring instruments and data acquisition and processing devices will not be described in detail here.

[0089] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A longitudinal loading device for longitudinal deformation testing of shield tunnels, characterized in that, include: A first and a second support that are horizontally positioned relative to each other and can move relative to each other; A first axial loading member rotatably mounted on a first support and a second axial loading member rotatably mounted on a second support, the first axial loading member and the second axial loading member being opposite to each other, are used to press against the axial ends of the tube segment sample group. An axial load loading mechanism is used to drive the first support and the second support to move the first axial loading member and the second axial loading member relative to each other, so that the first axial loading member and the second axial loading member apply axial load to the tube segment sample group at both ends of the axial direction. A bending moment loading mechanism is used to drive the first axial loading member and the second axial loading member to rotate, so that the first axial loading member and the second axial loading member apply bending moment to the tube segment sample group from both axial ends. as well as The vertical load loading mechanism is used to apply vertical loads to the segment sample group.

2. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 1, characterized in that: The first axial loading member and the second axial loading member are annular and both are vertically arranged. The first axial loading member and the second axial loading member have annular grooves on the side facing the tube segment sample group, which can be used for partial insertion of the end of the tube segment sample group.

3. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 1, characterized in that: The first axial loading member and the second axial loading member extend outward from their horizontal sides to form a first rotating shaft. The first rotating shaft is rotatably mounted on the first support and the second support, respectively. The axis of the first rotating shaft coincides with the axis of the tube sample.

4. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 3, characterized in that: Both the first axial loading member and the second axial loading member are connected to a first swing arm. One end of the first swing arm is connected to a bending moment loading mechanism, which is mounted on the first support and the second support. The first swing arm consists of two arms, one end of which is connected to form an acute angle. The connected end of the two arms is connected to the bending moment loading mechanism, and the other end of the two arms is connected to the end of the first axial loading member and the second axial loading member facing away from the tube segment sample group, respectively.

5. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 4, characterized in that: The lower end of the first swing arm is also fixed with a support member, and the bottom surfaces of the first axial loading member and the second axial loading member are in contact with or connected to the support member.

6. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 1, characterized in that: The vertical load loading mechanism includes a vertical reaction frame, a vertical drive mechanism mounted on the vertical reaction frame, and a second pusher mounted on the drive end of the vertical drive mechanism. The second pusher can move up and down under the drive of the vertical drive mechanism.

7. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 6, characterized in that: The vertical reaction frame is a cantilever beam structure, including a first column and a first cantilever. The first column is fixed to the support surface, and the first cantilever extends above the tube segment sample group. The vertical drive mechanism is directly or through the support structure installed on the first cantilever. The cantilever beam structure is an integral structure or a split structure with multiple spaced parts.

8. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 7, characterized in that: The first cantilever of the multiple cantilever beam structures is connected to the first longitudinal beam at the position above the tube sample group. The vertical drive mechanism includes a third cylinder or a third hydraulic cylinder arranged longitudinally at intervals. The number and position of the second pushing member correspond one-to-one with the third cylinder or the third hydraulic cylinder. The cylinder body of the third cylinder or the third hydraulic cylinder is fixed to the first longitudinal beam, and the piston rod is connected to the second pushing member.

9. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 8, characterized in that: The first column is fixed to a second cantilever located below the first cantilever. The first suspension is fixedly connected to both ends of the first longitudinal beam. The first suspension is also fixedly connected to the first and second cantilever at the corresponding positions. The first suspension is gantry-shaped, and the second longitudinal beam is connected between the suspended sides of the suspension.

10. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 9, characterized in that: The second pushing member includes an upper adapter block connected to the piston rod of the third cylinder or the third hydraulic cylinder, and an upper liner connected to the upper adapter block at its upper end. The upper liner is adapted to the upper part of the tube sample.

11. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 1, characterized in that: It also includes a first guide rod, which is arranged longitudinally. One end of the first guide rod is fixedly connected to the first support or the second support, and the other end is movably inserted into the second support or the first support. When the first support and the second support move relative to each other, the second support or the first support slides along the first guide rod.

12. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 1, characterized in that: It also includes a soil layer simulation mechanism, which includes a third pushing member and an elastic loading mechanism for applying an upward elastic force to the third pushing member.

13. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 12, characterized in that: The third pushing member includes a lower adapter block whose lower end is connected to the elastic loading mechanism and a lower liner whose lower end is connected to the lower adapter block. The lower liner is adapted to the lower part of the tube segment sample.

14. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 13, characterized in that: The number of elastic loading mechanisms corresponds one-to-one with the number and position of the third pushing member. Each elastic loading mechanism includes at least two support rods whose upper ends are connected to the third pushing member, a support plate located at the lower end of the at least two support rods, a second guide rod fixed to the support surface, and a top spring sleeved on the second guide rod. The second guide rod is movably inserted into the support plate, and the upper end of the top spring elastically abuts against the support plate.

15. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 14, characterized in that: It also includes a guide frame, a support rod is movably inserted into the guide frame, a pad is provided on the support surface, the lower part of the second guide rod is formed with external threads and screwed with a nut, the pad is provided with a corresponding screw hole, and the second guide rod is screwed onto the pad through the cooperation of the external threads and the screw hole.

16. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in any one of claims 1 to 15, characterized in that: The first and second supports are also provided with vertical adjustment mechanisms, and the first and second axial loading members are rotatably mounted on the vertical adjustment mechanisms.

17. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 16, characterized in that: The vertical adjustment mechanism includes a vertical guide rail fixed on a first support and a second support respectively, a lifting seat slidably mounted on the vertical guide rail via a slider, and an adjustment mechanism that drives the lifting seat to move up and down along the vertical guide rail. The first rotating shaft is rotatably mounted on the lifting seat directly or via a bearing seat with a bearing shaft.

18. The longitudinal loading device for longitudinal deformation testing of shield tunnels as described in claim 17, characterized in that: The adjustment mechanism includes a lead screw mounted on a first support and a second support, a lead screw nut fixed on a lifting seat and cooperating with the lead screw, and a drive component for driving the lead screw to rotate.

19. A loading method using the longitudinal loading device for longitudinal deformation testing of shield tunnels as described in any one of claims 1 to 18, characterized in that, Including the following steps: S1. According to the test requirements, select a segment sample group consisting of a predetermined number and length of segment samples, and drive the first support and the second support to move relative to each other so that the first axial loading member and the second axial loading member abut against the segment sample group at both ends of the axial direction. S2. According to the test requirements, drive the first and second supports to rotate to apply bending moments to the segment specimen group from both axial ends, and / or apply vertical loads to the predetermined segment specimens through the vertical load loading mechanism.

20. The loading method as described in claim 19, using the longitudinal loading device for longitudinal deformation testing of shield tunnels as described in any one of claims 1 to 18, characterized in that: In step S2, an upward elastic constraint force is applied to the tunnel segment sample through a soil simulation mechanism to simulate the constraint force exerted by the soil layer on the tunnel segment.

Images