Immersed tunnel DCM pile composite foundation centrifuge test preparation system

Abstract

The invention discloses an immersed tube tunnel DCM pile composite foundation centrifuge test preparation system, and relates to the technical field of immersed tube tunnel centrifuge tests.The test system assembly comprises a test model box, a centrifuge, a stirring grouting mechanism and a curing mechanism, and the test model box is a layered shear box and is used for preparing a test model comprising a foundation and a structure; the centrifugal machine is a large geotechnical centrifugal machine system and can be used for foundation centrifugal consolidation and subsequent dynamic tests; the stirring and grouting mechanism is used for stirring and grouting the foundation under the supergravity condition; and the solidification mechanism solidifies the slurry to form the DCM pile. The DCM pile is constructed in the supergravity state, the curing time is shortened by arranging the curing mechanism, the construction efficiency is improved, the stirring and grouting processes during actual construction are simulated by arranging the stirring and grouting mechanism, and the problems that a micro pile body difficultly reproduces the cement paste permeation and diffusion effect in a prototype, the pile-soil interface strength does not conform to the reality and the like are effectively solved; therefore, a model manufacturing foundation is provided for an immersed tunnel composite foundation test, and the test accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of centrifuge testing technology for immersed tunnels, and in particular to a centrifuge test preparation system for DCM pile composite foundation of immersed tunnels. Background Technology

[0002] As core projects of cross-sea channels such as the Hong Kong-Zhuhai-Macau Bridge and the Shenzhen-Zhongshan Bridge, the safety of subsea immersed tunnels is crucial to the development of national infrastructure. Deep cement mixing (DCM) composite foundations, as a foundation treatment method, have been used in projects like the Hong Kong-Zhuhai-Macau immersed tunnel project. They play an important role in reinforcing weak foundations of subsea immersed tunnels, reducing foundation settlement and uneven settlement at joints, and enhancing the seismic performance of the tunnel system. Therefore, scholars have conducted extensive experimental research on DCM piles (deep cement mixing piles) for immersed tunnels, focusing on the stability of immersed tunnels in complex marine environments. Centrifuge testing, as a testing method that can reproduce the real stress field, has undoubtedly become the most suitable way to study the static or dynamic characteristics of DCM composite foundations for subsea immersed tunnels. However, existing centrifuge simulation schemes, due to limitations in technology and scale, mostly use precast piles to simulate DCM pile composite foundations, which has certain limitations.

[0003] On the one hand, existing schemes mostly adopt the method of casting and curing precast piles by pouring foundation soil materials (such as kaolin) with micro-particle concrete for 28 days. The piles formed by this method are homogeneous piles, which have a certain degree of strength gradient distortion and cannot reproduce the gradient attenuation of the original cement-soil strength from the core to the boundary. On the other hand, the pre-embedded method requires drilling and soil extraction after centrifuge consolidation. During the drilling process, it is easily affected by manual operation, which can damage the soil structure. Moreover, the strength of the pile-soil interface cannot reach the actual mixing construction conditions, and the interface friction coefficient has a certain degree of decay. On the other hand, existing schemes lack micro-mixing equipment and cannot reproduce the soil mixing-grout coupling process during construction. Finally, since traditional concrete requires 28 days to reach the preset strength, the curing time under centrifugal hypergravity conditions is not in line with the time scale of the test. Even without the precast scheme, it is impossible to simulate grouting by adding micro-particle concrete grout in a centrifuge. In summary, the existing experimental conditions have certain limitations. Therefore, further research is needed on the experimental simulation of DCM pile composite foundations under centrifugal conditions with hypergravity. There is an urgent need for a method that can effectively improve the problem of difficulty in simulating actual DCM pile composite foundations in centrifuge tests of immersed tunnels, provide a model-making basis for dynamic tests of submarine immersed tunnels, and ensure the accuracy of the tests. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to propose a centrifuge test preparation system for immersed tunnel DCM pile composite foundations, thereby improving construction efficiency, providing a model-making basis for immersed tunnel composite foundation tests, and enhancing the accuracy of immersed tunnel composite foundation tests.

[0005] The centrifuge test preparation system for DCM pile composite foundation of immersed tunnel according to the present invention includes: a test system assembly, comprising a test model box, a mixing and grouting mechanism, and a curing mechanism; the test model box includes a main body, a base, and a mounting bracket; the mounting bracket and the main body are both fixed to the base and located above the base; the mounting bracket is fitted onto the main body; the main body and the base together define a laying space, within which a foundation is laid; the mixing and grouting mechanism is assembled onto the mounting bracket; the mixing and grouting mechanism is movable relative to the mounting bracket along a first direction, and the mixing and grouting mechanism is also movable along a second direction. The system is movable relative to the mounting bracket, with the first direction, the second direction, and the height direction of the test model box perpendicular to each other. The mixing and grouting mechanism is suitable for mixing the foundation and grouting after mixing. The curing mechanism is fixed in the laying space and is suitable for curing the grout in the foundation to form a deep cement mixing pile. The centrifuge and the test model box are layered shear boxes used to prepare test models including the foundation and structure. The centrifuge is a large geotechnical centrifuge system that can be used for centrifugal consolidation of the foundation and subsequent dynamic tests. The mixing and grouting mechanism mixes and grouts the foundation under hypergravity conditions. The curing mechanism cures the grout to form a DCM pile.

[0006] The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to the present invention can improve construction efficiency by setting a curing mechanism to reduce curing time, and improve the consistency between the interface strength of DCM pile and foundation and actual construction by setting a mixing and grouting mechanism to simulate the mixing and grouting process during actual construction. It can also improve the consistency between the grout penetration and diffusion process and actual construction, thereby providing a model making basis for immersed tunnel composite foundation test and improving the accuracy of immersed tunnel composite foundation test.

[0007] In some examples of the present invention, the test model box further includes: a positioning mechanism, which is mounted on the mounting bracket, and the mixing and grouting mechanism is movably mounted on the positioning mechanism so that the mixing and grouting mechanism is mounted on the mounting bracket through the positioning mechanism, and the positioning mechanism is used to drive the mixing and grouting mechanism to move along a first direction and a second direction.

[0008] In some examples of the present invention, the positioning mechanism includes: a first driving member, a first guide rail, a second guide rail, and a vertical rod. The main body of the model box is annular, and the main body of the model box and the base define an open laying space at the upper end. The mounting bracket has two mounting walls that are opposite to each other and spaced apart along a first direction. The main body of the model box is located between the two mounting walls. The upper end of the mounting wall is higher than the upper end of the main body of the model box. The upper end of the mounting wall is fixedly provided with a first guide rail extending along a second direction. The second guide rail extends along the first direction and is movably disposed on the first guide rail along the second direction. The vertical rod is movably disposed on the second guide rail along the first direction. The vertical rod is used to install the mixing and grouting mechanism. The first driving member is used to drive the second guide rail to move along the first guide rail, and the first driving member is also used to drive the vertical rod to move the mixing and grouting mechanism along the second guide rail, so that the mixing and grouting mechanism moves to the target position.

[0009] In some embodiments of the present invention, the vertical rod has a vertical guide rail, and the vertical guide rail extends along the extension direction of the vertical rod, and the mixing and grouting mechanism is slidably disposed on the vertical guide rail along the extension direction of the vertical guide rail.

[0010] In some examples of the present invention, the vertical rod is rotatably mounted on the second guide rail about a first direction, and the first driving member is also used to drive the vertical rod to drive the mixing and grouting mechanism to rotate synchronously.

[0011] In some examples of the present invention, the positioning mechanism further includes: a telescopic support rod, two second guide rails arranged along a second direction, a vertical rod disposed on one of the second guide rails, one end of the telescopic support rod connected to the other second guide rail, and the other end of the telescopic support rod connected to the vertical rod.

[0012] In some examples of the present invention, the grouting mechanism includes: a sleeve, a drilling component, a second driving component, and a driving storage device. The sleeve is fitted onto the drilling component, which includes a piezoelectric ceramic vibration actuator, a drill rod, and a drill bit. The piezoelectric ceramic vibration actuator is connected between the drill bit and the drill rod. The second driving component is adapted to drive the drilling component to rotate and move relative to the sleeve along the axial direction of the sleeve. A grouting channel communicating with the driving storage device is formed inside the drill bit, and a grouting hole communicating with the grouting channel is formed on the side wall of the drill bit. The driving storage device is used to store slurry and gas, and is adapted to drive the slurry or gas to flow into the grouting channel.

[0013] In some examples of the present invention, the drill bit includes a drill bit body and a helical rib. The drill bit body is constructed as a hollow structure to form a grouting channel inside the drill bit body. The outer peripheral wall of the drill bit body is fixed with a helical rib, which is arranged to spirally surround the drill bit body along the circumference of the drill bit body.

[0014] In some examples of the present invention, the drive storage device includes a drive pump and a storage tank, the storage tank being formed with a first storage cavity and a second storage cavity, the first storage cavity being for storing slurry and the second storage cavity being for storing gas, the drive pump being selectively connected to one of the first and second storage cavities to drive the drive pump to drive the slurry or gas into the grouting channel.

[0015] In some examples of the present invention, the main body of the model box includes multiple shear layers and multiple aluminum frame interlayer rubber pads, and the multiple shear layers and multiple aluminum frame interlayer rubber pads are alternately arranged along the arrangement direction of the main body of the model box and the base.

[0016] In some examples of the present invention, the test model box further includes a rubber membrane, at least a portion of which is disposed within the laying space and on the main body of the model box, and the rubber membrane is opposite to the inner surface of the main body of the model box facing the laying space.

[0017] In some examples of the present invention, the foundation includes a soft soil layer and a bearing layer, wherein the bearing layer is disposed between the soft soil layer and the base.

[0018] In some examples of the invention, the base is formed with at least one drainage channel to allow water in the laying space to drain out of the test model box.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a top view of the test system components according to an embodiment of the present invention;

[0022] Figure 2 This is an assembly diagram of the test system components and centrifuge according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the mixing and grouting mechanism according to an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of soft soil layer preconsolidation according to an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the construction of deep cement mixing piles according to an embodiment of the present invention;

[0026] Figure 6This is a schematic diagram of the excavation of the immersed tunnel foundation trench according to an embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram of the subgrade laying and immersed tunnel placement according to an embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of crushed stone backfilling according to an embodiment of the present invention;

[0029] Figure 9 This is a schematic diagram of the seawater layer arrangement according to an embodiment of the present invention.

[0030] Figure label:

[0031] Test system component 10;

[0032] Test model box 1; main body of model box 11; shear layer 111; aluminum frame interlayer rubber gasket 112; base 12; drainage channel 121; mounting bracket 13; mounting wall 131; laying space 14; positioning mechanism 15; first driving component 151; first guide rail 152; second guide rail 153; vertical rod 154; vertical guide rail 1541; telescopic support rod 155; rubber membrane 16;

[0033] 2. Grouting and mixing mechanism; 21. Sleeve; 22. Drilling component; 221. Piezoelectric ceramic vibration actuator; 222. Drill rod; 223. Drill bit; 2231. Grouting hole; 2232. Drill bit body; 2233. Helical rib; 2233. Second driving component; 24. Driving storage device;

[0034] Curing mechanism 3;

[0035] Foundation 4; Soft soil layer 41; Bearing layer 42;

[0036] Centrifuge 20; Rotary arm 5; Counterweight basket 6; Counterweight 61; Model box basket 7; Base 8; Data acquisition system 9;

[0037] 30 pre-consolidated loading block; 40 foundation trench; 50 immersed tunnel; 60 cushion layer; 70 backfill layer; 80 seawater layer; 90 deep cement mixing pile. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0039] The following is for reference. Figures 1-9 A centrifuge test preparation system for immersed tunnel DCM pile composite foundation is described according to an embodiment of the present invention.

[0040] like Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, the centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to the present invention includes: a test system component 10, which includes a test model box 1, a mixing and grouting mechanism 2, and a curing mechanism 3. The test model box 1 includes a main body 11, a base 12, and a mounting bracket 13. The mounting bracket 13 and the main body 11 are both fixed to the base 12 and are both located above the base 12. The mounting bracket 13 is sleeved on the main body 11. The main body 11 and the base 12 together define a laying space 14. Within the laying space 14... A foundation 4 is laid; a mixing and grouting mechanism 2 is mounted on a mounting bracket 13. The mixing and grouting mechanism 2 is movable relative to the mounting bracket 13 along a first direction and also movable relative to the mounting bracket 13 along a second direction. The first direction, the second direction, and the height direction of the test model box 1 are perpendicular to each other. The mixing and grouting mechanism 2 is suitable for mixing the foundation 4 and grouting after mixing; a curing mechanism 3 is fixed in the laying space 14. The curing mechanism 3 is suitable for curing the grout in the foundation 4 to form a deep cement mixing pile 90; a centrifuge 20 is used to solidify the foundation 4.

[0041] Both the mounting bracket 13 and the main body 11 of the model box are fixed to the base 12. For example, the mounting bracket 13 and the main body 11 of the model box can be fixed to the base 12 by means of screws, adhesives, etc. The thickness of the base 12 is 5mm-8mm, for example, the thickness of the base 12 can be 5mm, 7mm or 8mm. The base 12 can have multiple fixing holes. Part of the fixing holes is used to fix the base 12 to the vibration table, thereby fixing the test system component 10 to the vibration table. It is understood that the vibration table can simulate the vibration conditions required for the test. Another part of the fixing holes is used to fix the mounting bracket 13 to the base 12. The thickness of the main body 11 of the model box can be 5cm-10cm, for example, the thickness of the main body 11 of the model box can be 5cm, 7cm or 10cm, but this application is not limited to this. The thickness of the main body 11 of the model box can be other values ​​between 5cm and 10cm. It is understood that the size of the main body 11 of the model box can be freely designed according to the size requirements of the test.

[0042] Along the height direction of test model box 1, the height direction of test model box 1 is... Figure 5In the Z direction, both the mounting bracket 13 and the main body 11 of the model box are located above the base 12, and the mounting bracket 13 is fitted onto the main body 11 of the model box. The main body 11 of the model box and the base 12 together define the laying space 14 for the foundation 4. The mixing and grouting mechanism 2 is mounted on the mounting bracket 13. For example, the mixing and grouting mechanism 2 can be indirectly mounted on the mounting bracket 13 via a slide rail or via a motor, so that the mixing and grouting mechanism 2 can move relative to the mounting bracket 13 in either the first or second direction. The first direction is... Figure 1 The X direction, the second direction is... Figure 1 In the Y direction, the first direction, the second direction and the height direction of the test model box 1 are perpendicular to each other, that is, the X direction, Y direction and Z direction are perpendicular to each other.

[0043] The mixing and grouting mechanism 2 can mix the soil in the foundation 4 and then grout it. This configuration allows the mixing and grouting mechanism 2 to simulate the mixing and grouting process during actual construction, which is beneficial to improving the consistency between the interface strength of the deep cement mixing pile 90 and the foundation 4 and the actual construction. It is also beneficial to improve the consistency between the grout penetration and diffusion process and the actual construction, thereby providing a model for the composite foundation test of the immersed tunnel and improving the accuracy of the composite foundation test of the immersed tunnel.

[0044] As some embodiments of this application, the slurry components include an epoxy resin matrix, nano-calcium carbonate filler, photoinitiator, thixotropic agent, and toughening fibers. The epoxy resin matrix can be 50%-60% with a viscosity of 200 Pa·s-500 mPa·s. The epoxy resin matrix provides a curing skeleton for the deep cement mixing pile 90 and determines the final strength of the deep cement mixing pile 90. The nano-calcium carbonate filler content is 20%-30%, with an average particle size of 100 nm, which helps to adjust the elastic modulus and improve the interfacial friction between the foundation 4 and the deep cement mixing pile 90. The photoinitiator can be TPO-L, with a content of 2%-3% and an absorption peak wavelength of 380 nm-420 nm. Its function is to initiate the photocuring reaction and control the curing speed. The thixotropic agent can be fumed silica, with a content of 3%-5%, which imparts shear-thinning properties to the slurry. The toughening fiber can be carbon fiber with an aspect ratio of 200:1-150:1 to prevent cracking of the deep cement mixing pile 90. After construction, cubic test blocks of the deep cement mixing pile 90 need to be cast in the same way to determine their unconfined compressive strength. The unconfined compressive strength is not less than 1.6MPa.

[0045] The curing mechanism 3 can be, but is not limited to, a gallium nitride LED array. The curing mechanism 3 is fixed within the laying space 14. For example, the curing mechanism 3 can be fixed to the mixing and grouting mechanism 2 or the main body 11 of the model box by means of snap-fit ​​or adhesive bonding. Alternatively, a portion of the curing mechanism 3 can be distributed circumferentially along the mixing and grouting mechanism 2, while another portion can be evenly distributed on the external mounting bracket 13 on the top surface of the model box. As some embodiments of this application, the peak wavelength of the curing mechanism 3 is 395nm±5nm, which can accurately match the TPO-L absorption spectrum. The power of a single gallium nitride LED is 3W, the optical power density is 50mW / cm², and the strength index is that the slurry surface is cured to a compressive strength of 1.0MPa within 60s. Its heat dissipation adopts microchannel liquid cooling, ensuring that the chip junction temperature is less than 85°C under 100g centrifugal acceleration. This setup facilitates the smooth solidification of the grout within the foundation 4, forming a deep cement mixing pile 90. Furthermore, by setting up the solidification mechanism 3 to reduce the solidification time, the construction efficiency of the test system component 10 can be improved.

[0046] Centrifuge 20 includes a rotating arm 5, a counterweight basket 6, and a model box basket 7. Centrifuge 20 may also include a base 8, a data acquisition system 9, and a control system. The rotating arm 5 is rotatably mounted on the base 8. The counterweight basket 6 and the model box basket 7 are fixedly connected to both ends of the rotating arm 5, respectively. The counterweight basket 6 can be fitted with a counterweight 61, and the model box basket 7 can be fitted with the test system component 10. During the rotation of the rotating arm 5, both the counterweight basket 6 and the model box basket 7 can rotate around the base 8. Under the action of centrifugal force, the foundation 4 within the laying space 14 is solidified. The data acquisition system 9 is located on the base 8 and is communicatively connected to the control system. The data acquisition system 9 can transmit the working information of centrifuge 20 to the control system. The control system controls the centrifuge 20 to operate based on the received information, so that the foundation 4 within the laying space 14 is fully solidified, thereby completing the assembly of the test system component 10.

[0047] Specifically, the test model box 1 includes a main body 11, a base 12, and a mounting bracket 13. The main body 11 and the mounting bracket 13 are both fixed to the base 12 by bolts. Along the height direction of the test model box 1, the mounting bracket 13 and the main body 11 are both located above the base 12, and the mounting bracket 13 is fitted onto the main body 11. The main body 11 and the base 12 together define the laying space 14, and the foundation 4 is laid on the base 12 so that the foundation 4 is laid in the laying space 14.

[0048] The mixing and grouting mechanism 2 is mounted on the mounting bracket 13, and can move relative to the mounting bracket 13 in both the first and second directions, so that the mixing and grouting mechanism 2 can be moved above the target position (i.e., the pile formation position of the deep cement mixing pile 90), thereby mixing the soil 4 and grouting it after mixing. The curing mechanism 3 is fixed in the laying space 14, and the curing mechanism 3 can smoothly cure the grout in the soil 4 to form the deep cement mixing pile 90.

[0049] The counterweight 61 is assembled on the counterweight basket 6, and the test system component 10 is assembled on the model box basket 7. The control system controls the rotating arm 5 to rotate. At this time, both the counterweight basket 6 and the model box basket 7 can rotate around the base 8. The data acquisition system 9 transmits the working information of the centrifuge 20 to the control system. The control system continuously controls the centrifuge 20 to work according to the received information. Under the action of centrifugal force, the foundation 4 in the laying space 14 is consolidated.

[0050] Test model box 1 is a layered shear box used to prepare test models including foundation 4 and structure; centrifuge 20 is a large geotechnical centrifuge system that can be used for centrifugal consolidation of foundation 4 and subsequent dynamic tests; mixing and grouting mechanism 2 mixes and grouts foundation 4 under hypergravity conditions; curing mechanism 3 cures the grout to form DCM piles.

[0051] Therefore, by setting up the curing mechanism 3 to reduce the curing time, the construction efficiency can be improved. By setting up the mixing and grouting mechanism 2 to simulate the mixing and grouting process during actual construction, the consistency between the interface strength of the deep cement mixing pile 90 and the foundation 4 and the actual construction can be improved, as well as the consistency between the grout penetration and diffusion process and the actual construction. This provides a model-making basis for the composite foundation test of the immersed tunnel and improves the accuracy of the composite foundation test of the immersed tunnel.

[0052] In some examples of the present invention, such as Figure 1 and Figure 5 As shown, the test model box 1 may further include: a positioning mechanism 15, which is mounted on the mounting bracket 13, and the mixing and grouting mechanism 2 is movably mounted on the positioning mechanism 15 so that the mixing and grouting mechanism 2 is mounted on the mounting bracket 13 through the positioning mechanism 15. The positioning mechanism 15 is used to drive the mixing and grouting mechanism 2 to move along a first direction and a second direction.

[0053] The positioning mechanism 15 is mounted on the mounting bracket 13. For example, the positioning mechanism 15 can be mounted on the mounting bracket 13 by means of bolts, snap-fit, etc. The mixing and grouting mechanism 2 is movably mounted on the positioning mechanism 15 so that the mixing and grouting mechanism 2 is mounted on the mounting bracket 13 through the positioning mechanism 15. As some embodiments of this application, the positioning mechanism 15 can be constructed as a motor-slide rail mechanism, in which the mixing and grouting mechanism 2 is slidably set on the slide rail, and the motor drives the mixing and grouting mechanism 2 to move relative to the slide rail in either the first direction or the second direction. As some embodiments of this application, the positioning mechanism 15 can also be directly constructed as a motor. The mixing and grouting mechanism 2 is fixedly connected to the output end of the motor. The motor can directly drive the mixing and grouting mechanism 2 to move along the first direction or the second direction. However, this application is not limited to this. The positioning mechanism 15 can also be constructed in other forms, as long as it can achieve the effect of driving the mixing and grouting mechanism 2 to move along the first direction and the second direction to the target position (i.e., the pile formation position of the deep cement mixing pile 90). This allows the mixing and grouting mechanism 2 to mix the foundation 4 and inject grout after mixing, which is beneficial to smoothly simulate the mixing and grouting process during actual construction and improve the accuracy of the composite foundation test of the immersed tunnel.

[0054] In some examples of the present invention, such as Figure 1 and Figure 5 As shown, the positioning mechanism 15 may include: a first driving member 151, a first guide rail 152, a second guide rail 153, and a vertical rod 154. The main body 11 of the model box is annular, and the main body 11 and the base 12 define an open laying space 14 at the upper end. The mounting bracket 13 has two mounting walls 131 that are opposite to each other and spaced apart along a first direction. The main body 11 of the model box is located between the two mounting walls 131. The upper end of the mounting wall 131 is higher than the upper end of the main body 11 of the model box. The upper end of the mounting wall 131 is fixed with a... A first guide rail 152 extends along a second direction, and a second guide rail 153 extends along a first direction and is movably disposed on the first guide rail 152 along the second direction. A vertical rod 154 is movably disposed on the second guide rail 153 along the first direction. The vertical rod 154 is used to install the mixing and grouting mechanism 2. A first driving member 151 is used to drive the second guide rail 153 to move along the first guide rail 152, and the first driving member 151 is also used to drive the vertical rod 154 to move the mixing and grouting mechanism 2 along the second guide rail 153, so that the mixing and grouting mechanism 2 moves to the target position.

[0055] The model box body 11 is annular, and the model box body 11 and the base 12 together define the laying space 14, the upper end of the laying space 14 being open. The mounting bracket 13 has two mounting walls 131, which are arranged opposite to each other along a first direction and spaced apart along the first direction to form an installation space for assembling the model box body 11 between the two mounting walls 131. The model box body 11 is fixed in the installation space between the two mounting walls 131, and the upper end of the mounting wall 131 is higher than the upper end of the model box body 11, for example, the upper end of the mounting wall 131 is 10cm-15cm higher than the upper end of the model box body 11. This arrangement makes the structural design of the mounting wall 131 reasonable. When components such as the positioning mechanism 15 and the mixing and grouting mechanism 2 are installed on the mounting wall 131, the risk of interference between the positioning mechanism 15 and the mixing and grouting mechanism 2 and the model box body 11 can be reduced.

[0056] The first driving component 151 may be constructed as a motor, cylinder, etc. The first guide rail 152 and the second guide rail 153 may each be configured as at least one. For example, the first guide rail 152 and the second guide rail 153 may each be one, two, or more. The first guide rail 152 adopts a cross roller bearing slide, and the stroke is 1.2 times the length of the construction area where deep cement mixing piles 90 need to be carried out. This application takes the configuration of two first guide rails 152 as an example. The first guide rail 152 extends along the second direction, and the upper end of the mounting wall 131 is fixed with the first guide rail 152. The two first guide rails 152 are respectively set on two mounting walls 131 that are opposite to each other and spaced apart along the first direction. This configuration is beneficial to improving the working reliability of the first guide rail 152.

[0057] The second guide rail 153 adopts a precision lead screw guide rail, and its stroke is 1.2 times the width of the test model box 1. Under hypergravity conditions, the centrifugal deformation of the first guide rail 152 and the second guide rail 153 must be controlled within 0.3με to reduce the risk of excessive deformation of the first guide rail 152 and the second guide rail 153 during the consolidation of the foundation 4 through the centrifuge 20, which would lead to excessive differences between the test and the actual construction of the composite foundation 4 of the immersed tunnel 50. The second guide rail 153 extends along the first direction and is movably set on the first guide rail 152 along the second direction. The vertical rod 154 is movably set on the second guide rail 153 along the first direction. When the second guide rail 153 moves relative to the first guide rail 152, the vertical rod 154 moves with the first guide rail 152 along the second direction, and the vertical rod 154 is movable relative to the second guide rail 153 along the first direction, which is beneficial for the vertical rod 154 to be movable in both the first and second directions.

[0058] The vertical rod 154 is used to mount the mixing and grouting mechanism 2, so that the mixing and grouting mechanism 2 can move along the vertical rod 154 in both the first and second directions. It should be noted that the first driving member 151 is used to drive the second guide rail 153 to move along the first guide rail 152, and the first driving member 151 is also used to drive the vertical rod 154 to move the mixing and grouting mechanism 2 along the second guide rail 153, so that the first driving member 151 can provide power for the movement of the mixing and grouting mechanism 2, so that the mixing and grouting mechanism 2 can move to the target position.

[0059] In some examples of the present invention, such as Figure 5 As shown, the vertical rod 154 has a vertical guide rail 1541, and the vertical guide rail 1541 extends along the extension direction of the vertical rod 154. The mixing and grouting mechanism 2 is slidably disposed on the vertical guide rail 1541 along the extension direction of the vertical guide rail 1541.

[0060] The vertical rod 154 has a vertical guide rail 1541, which extends along the extension direction of the vertical rod 154. The mixing and grouting mechanism 2 is slidably set on the vertical guide rail 1541 along the extension direction of the vertical guide rail 1541. This arrangement allows the mixing and grouting mechanism 2 to move along the height direction of the test model box 1, so that the mixing and grouting mechanism 2 can move towards the foundation 4 along the height direction of the test model box 1. This enables the mixing and grouting mechanism 2 to extend into the foundation 4 to mix the foundation 4 and inject grout after mixing, which is beneficial to the subsequent formation of deep cement mixing piles 90.

[0061] In some examples of the present invention, such as Figure 5 As shown, the vertical rod 154 is rotatably mounted on the second guide rail 153 about a first direction, and the first driving member 151 is also used to drive the vertical rod 154 to drive the mixing and grouting mechanism 2 to rotate synchronously.

[0062] The vertical rod 154 is rotatably mounted on the second guide rail 153 around a first direction. The first driving member 151 is also used to drive the vertical rod 154 to drive the mixing and grouting mechanism 2 to rotate synchronously. This arrangement allows the vertical rod 154 to drive the mixing and grouting mechanism 2 to deflect, thereby achieving the effect of deep cement mixing piles forming at an angle of 90 degrees. It should be noted that the first driving member 151 is a micro stepper motor. More specifically, the first driving member 151 is a two-stage two-phase hybrid stepper motor with an outer diameter of 8mm, a length of 20mm, a step angle of 1.8°, and a holding torque of 50mN / m. This allows the first driving member 151 to simultaneously drive the second guide rail 153 to move along the first guide rail 152, drive the vertical rod 154 to move the mixing and grouting mechanism 2 along the second guide rail 153, and drive the vertical rod 154 to rotate synchronously, achieving a precise positioning effect for the mixing and grouting mechanism 2.

[0063] In some examples of the present invention, such as Figure 1 and Figure 5 As shown, the positioning mechanism 15 may further include: a telescopic support rod 155, two second guide rails 153 arranged along a second direction, a vertical rod 154 disposed on one of the second guide rails 153, one end of the telescopic support rod 155 connected to the other second guide rail 153, and the other end of the telescopic support rod 155 connected to the vertical rod 154.

[0064] There are two second guide rails 153, which are arranged along the second direction. The vertical rod 154 is set on one of the second guide rails 153. One end of the telescopic support rod 155 is connected to the other second guide rail 153, and the other end of the telescopic support rod 155 is connected to the vertical rod 154. The first driving member 151 can drive the vertical rod 154 to drive the mixing and grouting mechanism 2 to rotate synchronously, while stretching or contracting the telescopic support rod 155, so as to precisely control the length of the telescopic support rod 155 and achieve the effect of matching the length of the telescopic support rod 155 with the deflection angle of the vertical rod 154. This is beneficial to improving the stability and quality of the deep cement mixing pile 90 inclined pile formation.

[0065] In some examples of the present invention, such as Figure 3 As shown, the grouting mechanism 2 may include: a sleeve 21, a drilling component 22, a second driving component 23, and a driving storage device 24. The sleeve 21 is sleeved on the drilling component 22. The drilling component 22 includes a piezoelectric ceramic vibration actuator 221, a drill rod 222, and a drill bit 223. The piezoelectric ceramic vibration actuator 221 is connected between the drill bit 223 and the drill rod 222. The second driving component 23 is adapted to drive the drilling component 22 to rotate and move relative to the sleeve 21 along the axial direction of the sleeve 21. A grouting channel communicating with the driving storage device 24 is formed inside the drill bit 223. A grouting hole 2231 communicating with the grouting channel is formed on the side wall of the drill bit 223. The driving storage device 24 is used to store grout and gas. The driving storage device 24 is adapted to drive the grout or gas to flow into the grouting channel.

[0066] The sleeve 21 is fitted onto the drill bit 22. The sleeve 21 is used for determining the pile type and providing wall protection during the construction phase of the deep cement mixing pile 90. Understandably, during the drilling process of the drill bit 22, the sleeve 21 can reduce the risk of collapse of the surrounding foundation 4 or interference with the drilling operation of the drill bit 22. The sleeve 21 is constructed of 316L stainless steel with an outer diameter of 10mm-40mm. For example, the outer diameter of the sleeve 21 can be 10mm, 20mm, or 40mm, and the wall thickness is 0.3mm. The end of the sleeve 21 facing the foundation 4 is sharpened to allow it to better penetrate the foundation 4. A piezoelectric ceramic vibration actuator 221 is connected between the drill bit 223 and the drill rod 222. It assists in vibration during the cutting of the foundation 4 by the drill bit 223 and during grouting. The vibration frequency of the piezoelectric ceramic vibration actuator 221 is 20kHz, and the amplitude is 2μm. This arrangement can reduce the strength of part of the foundation 4, which is beneficial for grout penetration and solidification.

[0067] The second drive component 23 can be, but is not limited to, a motor, a cylinder, etc. As some embodiments of this application, the second drive component 23 is constructed as a brushless DC motor with an outer diameter of 15mm, a length of 40mm, a rated voltage of 50W, and a rated speed of 0rpm-500rpm to achieve continuous operation under centrifugal acceleration. The second drive component 23 can drive the drill rod 22 to rotate and move relative to the sleeve 21 along the axial direction of the sleeve 21. The drill rod 222 can be constructed of 304 stainless steel with an outer diameter of 5mm-20mm, an inner diameter of 3mm-15mm, a hollow internal structure to facilitate slurry flow, and a length of 50mm-400mm.

[0068] The drill bit 223 can be constructed of 304 stainless steel. A grouting channel communicating with the drive storage device 24 is formed within the drill bit 223. Grouting holes 2231 are formed on the sidewall of the drill bit 223, communicating with the grouting channel. The grouting holes 2231 can be arranged in a radial spiral array with a spacing of 2mm-4mm and a diameter of 0.3mm, enabling 360° full grouting. Furthermore, a miniature duckbill valve (not shown in the figure) is installed on the outside of the grouting holes 2231. The miniature duckbill valve is made of silicone and has an opening pressure of 0.05MPa. The miniature duckbill valve can reduce the risk of soil backflow clogging the grouting channel.

[0069] The drive storage device 24 is used to store grout and gas. The drive storage device 24 can drive the grout or gas into the grouting channel. Before injecting the grout into the foundation 4, the drive storage device 24 first drives the gas into the grouting channel and continues into the foundation 4. The gas can be carbon dioxide. The carbon dioxide injected into the foundation 4 can loosen the clay layer in the foundation 4, promote the subsequent grout penetration and solidification, thereby improving the pile formation effect of the deep cement mixing pile 90.

[0070] In some examples of the present invention, such as Figure 3 As shown, the drill bit 223 includes a drill bit body 2232 and a spiral rib 2233. The drill bit body 2232 is constructed as a hollow structure to form a grouting channel inside the drill bit body 2232. The spiral rib 2233 is fixedly provided on the outer peripheral wall of the drill bit body 2232. The spiral rib 2233 is arranged to spirally surround the drill bit body 2232 along the circumference of the drill bit body 2232.

[0071] The drill bit 223 includes a drill bit body 2232 and a spiral rib 2233. The drill bit body 2232 and the spiral rib 2233 can be fixedly connected by means of integral molding, welding, etc. The drill bit body 2232 has a hollow structure with a diameter consistent with that of the drill rod 222, so as to form a grouting channel inside the drill bit body 2232. The spiral rib 2233 is fixed on the outer peripheral wall of the drill bit body 2232. The spiral rib 2233 runs along the drill bit body 2232. The circumferential spiral surrounds the drill bit body 2232. As some embodiments of this application, the outer diameter of the drill bit 223 is 10mm-40mm, the height of the spiral rib 2233 is 1mm-2mm, the pitch is 5mm-10mm, the rib width is 1mm-3mm, and the grouting hole 2231 is located 1mm behind the spiral rib 2233. The negative pressure generated by the rotation of the spiral rib 2233 can be used to promote the penetration of grout, thereby further improving the pile formation effect of the deep cement mixing pile 90.

[0072] In some examples of the present invention, the drive storage device 24 may include a drive pump (not shown) and a storage tank (not shown), the storage tank having a first storage cavity and a second storage cavity, the first storage cavity for storing slurry and the second storage cavity for storing gas, the drive pump selectively communicating with one of the first and second storage cavities to drive the drive pump to drive the slurry or gas into the grouting channel.

[0073] The drive pump can be configured as a micro-plunger pump, with dimensions of 25mm × 15mm × 10mm, a flow rate range of 0.01mL / s-1.0mL / s, an output pressure of 0MPa-0.8MPa, and a maximum instantaneous pressure of 1.2MPa. The storage tank has a first storage chamber and a second storage chamber. The first storage chamber is used to store slurry, and the second storage chamber is used to store gas. The drive pump is selectively connected to one of the first and second storage chambers to provide pressure to the slurry or gas, thereby driving the slurry or gas to flow into the grouting channel.

[0074] Specifically, the drive pump is connected to the second storage chamber, injecting gas into the foundation 4 to loosen the clay layer and promote subsequent grout penetration and solidification. After the gas injection is completed, the drive pump is no longer connected to the second storage chamber, but is connected to the first storage chamber to drive the grout into the injection channel. It should be noted that the storage tank may, but is not limited to, be constructed of carbon fiber composite material, with a first storage chamber volume of 50mL-150mL, a second storage chamber volume of 30mL-90mL, a grout flow rate of 0.01mL / s-0.5mL / s, and a leakage rate of less than 0.1μL / h.

[0075] In some examples of the present invention, such as Figure 5 As shown, the main body 11 of the model box includes multiple shear layers 111 and multiple aluminum frame interlayer rubber pads 112. The multiple shear layers 111 and multiple aluminum frame interlayer rubber pads 112 are alternately arranged along the arrangement direction of the main body 11 of the model box and the base 12.

[0076] The model box body 11 includes multiple annular shear layers 111 and multiple aluminum frame interlayer rubber pads 112. For example, there can be two, three, ten, or more shear layers 111 and aluminum frame interlayer rubber pads 112. The multiple shear layers 111 and multiple aluminum frame interlayer rubber pads 112 are arranged alternately along the arrangement direction of the model box body 11 and the base 12. That is, an aluminum frame interlayer rubber pad 112 is provided between any two adjacent shear layers 111. The aluminum frame interlayer rubber pad 112 is in contact with two adjacent shear layers 111. The interlayer rubber gasket 112 of the aluminum frame can be, but is not limited to, made of neoprene rubber, and is bonded to the bottom of the upper adjacent shear layer 111. The interlayer rubber gasket 112 of the aluminum frame can cause relative slippage between adjacent shear layers 111. The relative slippage distance between any two adjacent shear layers 111 is ±3mm. This setting can better simulate the free boundary under dynamic load conditions, improve the consistency between the test and the actual construction, and thus improve the accuracy of the composite foundation test of the immersed tunnel.

[0077] In some examples of the present invention, such as Figure 5 As shown, the test model box 1 also includes a rubber membrane 16, at least a portion of which is disposed within the laying space 14 and fixed to the main body 11 of the model box, and the rubber membrane 16 is opposite to the inner surface of the main body 11 of the model box facing the laying space 14.

[0078] The rubber membrane 16 can be, but is not limited to, a rubber mold, a plastic film, etc. The end shear layer 111 facing away from the base 12 among the multiple shear layers 111 can have pre-reserved assembly holes for assembling the rubber membrane 16. In some embodiments of this application, a portion of the rubber membrane 16 is disposed within the laying space 14 and fixed to the main body of the model box 11. In some embodiments of this application, all of the rubber membrane 16 is disposed within the laying space 14 and fixed to the main body of the model box 11. Furthermore, the rubber membrane 16 faces the inner surface of the main body of the model box 11 facing the laying space 14. Further, the rubber membrane 16 is tightly attached to the main body of the model box 11, and its thickness is 2mm, which can improve the waterproofness of the main body of the model box 11 and reduce the risk of soil particles in the foundation 4 entering the shear layer 111.

[0079] In some examples of the present invention, such as Figure 5 As shown, the foundation 4 may include a soft soil layer 41 and a bearing layer 42, with the bearing layer 42 located between the soft soil layer 41 and the base 12.

[0080] Among them, the deep cement mixing pile 90 is formed in the soft soil layer 41. The soil particles of the bearing layer 42 are ISO standard coarse sand with a particle size of 1.0mm-2.0mm. The sand rain method is used for construction. The relative density needs to be greater than 90%. Before the sand rain method construction, the drop distance and opening of the coarse sand need to be marked. A layer of geotextile and a layer of filter paper are laid on the top surface of the coarse sand in sequence. The bearing layer 42 is set between the soft soil layer 41 and the base 12, which can play both the role of bearing support and drainage.

[0081] In some examples of the present invention, such as Figure 5 As shown, the base 12 has at least one drainage channel 121 to allow water in the laying space 14 to be discharged from the test model box 1 through the drainage channel 121.

[0082] The base 12 has at least one drainage channel 121. For example, the base 12 has one, two or more drainage channels 121. The drainage channel 121 can be composed of permeable stone, filter paper, drainage pipe and drainage valve. The drainage valve can selectively open or close the drainage pipe. During the consolidation process of the foundation 4, the drainage valve can be opened to achieve the effect of water in the laying space 14 being discharged from the test model box 1 through the drainage channel 121.

[0083] As some embodiments of this application, such as Figure 4- As shown in Figure 9, the construction steps of the centrifuge test preparation system for the DCM pile composite foundation of the immersed tunnel include: S1, pre-consolidation of the soft soil layer 41, placing the pre-consolidation loading block 30 on the soft soil layer 41, applying pressure to the soft soil layer 41 with the pre-consolidation loading block 30 to expel water from the soft soil layer 41, thereby pre-consolidating the soft soil layer 41. S2, consolidation of the centrifuge 20 and construction of the deep cement mixing pile 90. S3, excavation of the foundation trench 40 of the immersed tunnel 50. S4, laying of the cushion layer 60 and sinking of the immersed tunnel 50. S5, backfilling of the backfill layer 70 with crushed stone. S6, setting of the seawater layer 80. S7, conducting dynamic tests.

[0084] As some embodiments of this application, the pre-consolidation process of soft soil layer 41 includes: S11, preparing kaolin powder into kaolin slurry at twice the liquid limit. Turning on the vacuum mixer, adding kaolin powder and degassing water, and vacuum mixing for 12 hours under -100 kPa conditions.

[0085] S12. Lay a bearing layer 42 at the bottom of the model box. The soil particles are ISO standard coarse sand with a particle size of 1.0mm-2.0mm. The sand rain method is used for construction. The relative density should be greater than 90%. Before the sand rain method is constructed, the drop distance and opening of the coarse sand should be marked. Then, a layer of geotextile and a layer of filter paper are laid on the top surface of the coarse sand. The bearing layer 42 can serve both as a bearing layer and a drainage layer.

[0086] S13. Layered preconsolidation: Apply Vaseline to the rubber membrane 16 inside the test system component 10, and slowly pour the kaolin mud required for the current soil layer into the test system component 10 along the inner wall of the test system component 10. Filter paper and geotextile are laid on the top surface of the mud in sequence, and the preconsolidation loading block 30 is used to load the soil layer in stages of 1 kPa, 2 kPa, 4 kPa, 8 kPa, 16 kPa, etc. During each loading stage, the displacement and pore pressure of the soft soil layer 41 need to be monitored. When the displacement is stable and the excess pore water pressure is dissipated, the preconsolidation is considered to be completed. The maximum consolidation pressure is taken as the effective stress at the middle height of the prototype corresponding to the current soft soil layer 41.

[0087] S14. After the pre-consolidation is completed, the load is unloaded in stages. After each stage of load is unloaded, the next stage of unloading should be carried out only after the settlement and pore pressure have stabilized. After all the unloading is completed, the sensors required for the dynamic test are set up on the top surface of the soft soil layer 41.

[0088] As some embodiments of this application, the construction process of deep cement mixing pile 90 includes: S21, equipment installation and positioning: install the first guide rail 152, the second guide rail 153, the vertical rod 154, and the telescopic support rod 155 on the installation bracket 13. After the installation of the mixing and grouting mechanism 2 is completed, debug the control system to ensure that the pile position information can be accurately determined by input positioning. Correct the pile position by laser alignment instrument, and the error should be less than 0.2mm.

[0089] S22. Sensor Deployment: Deploy the required sensors within 90° of the deep cement mixing pile in the dynamic test scheme, including displacement gauges, pore pressure gauges, earth pressure gauges, accelerometers, and bending elements.

[0090] S23. Centrifuge 20 consolidation: The soft soil layer 41 is consolidated using centrifuge 20. The centrifugal acceleration is gradually increased to the set acceleration. Gradients such as 1g, 2g, 4g, 8g, 16g, 32g, and 64g can be used to gradually increase the centrifugal acceleration. The settlement of the soft soil layer 41 and the pore water pressure need to be monitored at each level. When the settlement is stable and the ultra-clean pore water pressure has dissipated, the consolidation is considered complete, and the next level of centrifugal acceleration can be increased. The drainage valve of the drainage channel 121 needs to be opened during the consolidation process.

[0091] S24. Stirring and sinking: After the soft soil layer 41 is consolidated under the last stage of centrifugal acceleration, drive the sleeve 21 to sink to 20mm below the soft soil layer 41. Then start the drilling component 22 and sink 40mm at a speed of 0.5mm / s-1.5mm / s. The rotation speed can be 100rpm-300rpm. When the torque of the spiral rib 2233 is greater than 5mN·m, it will automatically lift 0.5mm and sink again.

[0092] S25. Injecting carbon dioxide: After the drill bit 22 sinks 20mm, pause for 2s, sink the sleeve 21 another 20mm, and inject carbon dioxide gas through the grouting hole 2231 below the spiral rib 2233 of the drill bit 223 to reduce the local water content and lightly loosen the soft soil layer 41.

[0093] S26. Grouting and mixing: Grouting is started after the design depth is reached. The grouting pressure can be 0.1MPa-0.3MPa. First, the first lifting and mixing is carried out. The lifting speed of drill rod 222 and sleeve 21 is 0.8mm / s, and the grouting volume is 70%. Then, the sinking and re-mixing is carried out. The sinking speed can be 1.0mm / s, and the grouting volume is 30%. Finally, the third lifting and re-mixing is carried out at a speed of 1.0mm / s, without grouting.

[0094] As some embodiments of this application, the excavation process of the foundation trench 40 of the immersed tunnel 50 includes: S31, after the construction of the soft soil layer 41 foundation 4 and the deep cement mixing composite foundation 4 of the immersed tunnel 50 is completed, the centrifugal acceleration is gradually reduced to 1g.

[0095] S32. The soft soil layer 41 foundation 4 is sloped in stages, with slope ratios of 1:7, 1:4, and 1:3 from far to near. During the slope grading process, the cutting surface of the deep cement mixing pile 90 must be intact to avoid damaging its bearing characteristics.

[0096] As some embodiments of this application, in the model making and construction steps, the immersed tunnel 50 is cast using micro-particle concrete and reinforcement is considered. When carrying out similar design, it is necessary to consider similarity in size, stiffness, and bending strength. After installing earth pressure gauges, pore pressure gauges, accelerometers, and strain gauges on the tunnel, they are placed on the top surface of the cushion layer 60.

[0097] In some embodiments, the crushed stone backfilling in the model making construction steps takes into account similar particle size, uses ISO standard coarse sand, and the slope ratio is 1:2-1:4.

[0098] The beneficial effects of the technical solution provided by this invention include: fully leveraging the structural advantages of cement mixing piles 90 at different depths, improving problems such as damage to the soft foundation 4 of the immersed tunnel 50, and enhancing the construction accuracy and pile-soil interface strength of the precast pile system. This invention employs deep cement mixing piles 90 under hypergravity conditions. Compared to the traditional experimental scheme of precast cement-soil piles and borehole installation, the deep cement mixing pile 90 micro-piling system can accurately realize the mixing and grouting process during the construction of the deep cement mixing pile 90 composite foundation 4. This effectively solves the problem of difficulty in simulating the actual mixing process in centrifuge 20 tests and the inconsistency between the mechanical properties of the model pile material and the prototype pile. Furthermore, the mixing and grouting mechanism 2 can achieve the construction of mixing piles at the 5mm-10mm level, precisely simulating the cement slurry diffusion process, solving the problem of micro-piles being unable to reproduce the slurry penetration and diffusion effect in the prototype and the discrepancy between the pile-soil interface strength and the actual strength. In addition, the curing mechanism 3 can solve the problem of excessively long curing time for deep cement mixing piles 90 to form effective strength under hypergravity conditions, thereby improving construction efficiency. This invention can effectively improve the problem of difficulty in simulating actual deep cement mixing pile 90 composite foundation 4 in the test, and provide a model making basis for the composite foundation test of submarine immersed tunnel, ensuring the accuracy of the test.

[0099] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0100] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0101] In the description of this invention, "a plurality of" means two or more.

[0102] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0103] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0104] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A centrifuge test preparation system for immersed tunnel DCM pile composite foundation, characterized in that, include: The test system components include a test model box, a mixing and grouting mechanism, and a curing mechanism. The test model box includes a main body, a base, and a mounting bracket. The mounting bracket and the main body are both located above the base. The mounting bracket is fitted onto the main body. The main body and the base together define a laying space, and a foundation is laid within the laying space. The mixing and grouting mechanism is mounted on the mounting bracket. The mixing and grouting mechanism is movable relative to the mounting bracket along a first direction and also movable relative to the mounting bracket along a second direction. The first direction, the second direction, and the height direction of the test model box are perpendicular to each other. The mixing and grouting mechanism is adapted to mix the foundation and grout after mixing. The curing mechanism is fixed within the laying space, and the curing mechanism is adapted to cure the grout in the foundation to form a deep cement mixing pile. The centrifuge, the test model box being a layered shear box, is used to prepare a test model including the foundation and structure; the centrifuge is a large geotechnical centrifuge system, which can be used for centrifugal consolidation of the foundation and subsequent dynamic testing; the mixing and grouting mechanism mixes and grouts the foundation under hypergravity conditions; the solidification mechanism solidifies the grout to form DCM piles.

2. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 1, characterized in that, The test model box further includes a positioning mechanism, which is mounted on the mounting bracket, and the mixing and grouting mechanism is movably mounted on the positioning mechanism so that the mixing and grouting mechanism is mounted on the mounting bracket through the positioning mechanism. The positioning mechanism is used to drive the mixing and grouting mechanism to move along the first direction and the second direction.

3. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 2, characterized in that, The positioning mechanism includes a first driving member, a first guide rail, a second guide rail, and a vertical rod. The main body of the model box is annular, and the main body of the model box and the base define an open laying space at the upper end. The mounting bracket has two mounting walls that are opposite to each other and spaced apart along the first direction. The main body of the model box is located between the two mounting walls. The upper end of the mounting wall is higher than the upper end of the main body of the model box. The upper end of the mounting wall is fixed with the first guide rail extending along the second direction. The second guide rail extends along the first direction and is movably disposed on the first guide rail along the second direction. The vertical rod is movably disposed on the second guide rail along the first direction. The vertical rod is used to mount the mixing and grouting mechanism. The first driving member is used to drive the second guide rail to move along the first guide rail, and the first driving member is also used to drive the vertical rod to move the mixing and grouting mechanism along the second guide rail, so that the mixing and grouting mechanism moves to the target position.

4. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 3, characterized in that, The vertical rod has a vertical guide rail, and the vertical guide rail extends along the extension direction of the vertical rod. The mixing and grouting mechanism is slidably disposed on the vertical guide rail along the extension direction of the vertical guide rail.

5. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 3, characterized in that, The vertical rod is rotatably mounted on the second guide rail about the first direction, and the first driving member is also used to drive the vertical rod to drive the mixing and grouting mechanism to rotate synchronously.

6. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 5, characterized in that, The positioning mechanism further includes: a telescopic support rod, two second guide rails arranged along the second direction, a vertical rod disposed on one of the second guide rails, one end of the telescopic support rod connected to the other second guide rail, and the other end of the telescopic support rod connected to the vertical rod.

7. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 1, characterized in that, The grouting mechanism includes a sleeve, a drilling component, a second driving component, and a driving storage device. The sleeve is fitted onto the drilling component, which includes a piezoelectric ceramic vibration actuator, a drill rod, and a drill bit. The piezoelectric ceramic vibration actuator is connected between the drill bit and the drill rod. The second driving component is adapted to drive the drilling component to rotate and move relative to the sleeve along the axial direction of the sleeve. A grouting channel communicating with the driving storage device is formed inside the drill bit, and a grouting hole communicating with the grouting channel is formed on the side wall of the drill bit. The driving storage device is used to store slurry and gas, and is adapted to drive the slurry or gas to flow into the grouting channel.

8. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 7, characterized in that, The drill bit includes a drill bit body and a spiral rib. The drill bit body is constructed as a hollow structure to form the grouting channel inside the drill bit body. The spiral rib is fixed on the outer peripheral wall of the drill bit body and is arranged to spirally surround the drill bit body along the circumference of the drill bit body.

9. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to claim 7, characterized in that, The driving storage device includes a driving pump and a storage tank. The storage tank forms a first storage cavity and a second storage cavity. The first storage cavity is used to store the slurry, and the second storage cavity is used to store the gas. The driving pump is selectively connected to one of the first storage cavity and the second storage cavity so that the driving pump drives the slurry or the gas to flow into the grouting channel.

10. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to any one of claims 1-9, characterized in that, The main body of the model box includes multiple layered aluminum frames and multiple interlayer rubber pads of the aluminum frames. The multiple sheared layers and the multiple interlayer rubber pads of the aluminum frames are alternately arranged along the arrangement direction of the main body of the model box and the base.

11. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to any one of claims 1-9, characterized in that, The test model box further includes a rubber membrane, at least a portion of which is disposed within the laying space and on the main body of the model box, and the rubber membrane is opposite to the inner surface of the main body of the model box facing the laying space.

12. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to any one of claims 1-9, characterized in that, The foundation includes a soft soil layer and a bearing layer, wherein the bearing layer is disposed between the soft soil layer and the base.

13. The centrifuge test preparation system for immersed tunnel DCM pile composite foundation according to any one of claims 1-9, characterized in that, The base has at least one drainage channel to allow water in the laying space to be discharged from the test model box through the drainage channel.

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