Loading assembly for spherical wave loading test specimen of soil material and preparation method and loading system thereof

Abstract

The application provides a loading assembly for a spherical wave loading sample of soil material, a preparation method of the loading assembly and a loading system to solve the problem that the regular spherical shape of an explosive ball is damaged or even dangerous problems occur when the spherical wave loading sample is made. The loading assembly comprises a detonating cord, an outer shielding tube, an inner shielding tube, a protective soil core and an explosive ball. A semicircular notch is coaxially arranged at the lower end of the protective soil core. A through hole is arranged in the area above the semicircular notch. One end of the inner shielding tube is arranged in the through hole, and the other end is arranged above the protective soil core. The outer shielding tube is sleeved outside the inner shielding tube, and the lower end of the outer shielding tube is arranged on the protective soil core. The upper half of the explosive ball is arranged in the semicircular notch. The lower end of the detonating cord is connected with the explosive ball, and the upper end of the detonating cord is arranged outside after penetrating through the inner shielding tube. The application further provides a preparation method based on the assembly and a loading system.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of explosion impact dynamics of rock-soil materials, and particularly relates to a loading assembly for a spherical wave loading sample of soil materials, a preparation method thereof and a loading system. BACKGROUND

[0002] The dynamic mechanical properties of rock-soil media have a significant influence on the energy coupling of underground explosion and the propagation of stress waves, and it is of great academic value and engineering significance to clarify the dynamic mechanical properties of rock-soil media under explosion load.

[0003] At present, the means for studying the dynamic mechanical properties of rock-soil media mainly include Hopkinson bar test, flat plate impact test and spherical wave loading test. The Hopkinson bar loads the material in one dimension, and can be used to study the dynamic mechanical properties of the material under medium-high strain rate. The flat plate impact test loads the material in one dimension, and can be used to study the dynamic mechanical properties of the material under high pressure and high strain rate. The spherical wave loads the material in spherical wave, and can be used to study the dynamic mechanical properties of the material under three-dimensional stress-strain conditions, and can provide a more accurate material model for the simulation of underground explosion seismic waves.

[0004] The spherical wave loading test in the laboratory studied by Lu Qiang et al. (Lu Qiang, Wang Zhanjiang, Zhu Yurong, et al. Time-domain and frequency-domain analysis of measured spherical wave particle velocity in granite [J]. Modern Applied Physics, Vol. 9(4), 2018.12.) is to place a spherical explosive at the center of the sample, and a flexible detonating cord is drawn from the center of the explosive sphere for initiation. A circular ring-shaped particle velocity meter made of enameled wire is embedded on the central plane in the height direction of the sample, and then the entire sample is placed in a magnetic field. When the explosive sphere explodes to cause the particles in the medium to move, it will drive the particle velocity meter to move together, thereby cutting the magnetic induction lines to form an induced electromotive force, and the particle velocity in the medium can be obtained by measuring the induced electromotive force.

[0005] In the spherical wave loading test of rock-soil materials, the explosive sphere and the flexible detonating cord are the dynamic loading source. In order to ensure the accuracy and repeatability of the test, the shape and position of the explosive sphere and other parameters need to be ensured to be accurate enough during the sample preparation process. Considering the flexibility and adjustability of the porosity and water content of rock-soil materials, a mixture of fine loess and fine sand is used as raw material for sample preparation. However, since the sand particles are sharp and hard, if the explosive sphere is directly embedded in the mixture for pressing, the sand particles can easily pierce the surface of the explosive sphere, not only destroying its original regular spherical shape, but also causing danger. SUMMARY

[0006] The application aims at solving the problem that when a mixture of loess and fine sand is used as raw material to make a spherical wave loading test sample, the sand particles are sharp and hard, and when a charge ball is directly embedded in the mixture for pressing, the sand particles can easily pierce the surface of the charge ball, which can damage the regular spherical shape of the charge ball, and even cause danger.

[0007] To achieve the above-mentioned purpose, the application adopts the technical scheme of:

[0008] A loading assembly for a soil material spherical wave loading test sample, which is arranged in a sample to be tested, and is characterized in that it comprises a detonating cord, an outer shielding tube, an inner shielding tube, a protective soil core and a charge ball.

[0009] The inner diameter of the inner shielding tube is greater than the diameter of the detonating cord, and the density of the protective soil core is the same as that of the sample to be tested.

[0010] The lower end of the protective soil core is coaxially provided with a semicircular notch matching the size of the charge ball, and the area of the protective soil core above the semicircular notch is coaxially provided with a through hole communicating with the semicircular notch, the diameter of the through hole matches the outer diameter of the inner shielding tube, one end of the inner shielding tube is arranged in the through hole, and the other end is located above the protective soil core, the outer shielding tube is arranged outside the inner shielding tube with a gap therebetween, the lower end of the outer shielding tube is arranged on the protective soil core, and the upper end is located outside the sample to be tested.

[0011] The upper half of the charge ball is arranged in the semicircular notch, the lower end of the detonating cord is connected with the charge ball, and the upper end of the detonating cord is arranged outside after passing through the inner shielding tube, and the lower half of the charge ball is arranged in the sample to be tested.

[0012] Further, the inner shielding tube comprises a first inner shielding tube and a second inner shielding tube which are coaxially arranged and have an inner diameter greater than that of the detonating cord.

[0013] One end of the second inner shielding tube is arranged in the through hole, and the other end is located in the outer shielding tube, one end of the first inner shielding tube is located in the outer shielding tube and communicates with the second inner shielding tube, and the other end passes out of the upper end of the outer shielding tube, and the other end of the detonating cord passes through the second inner shielding tube and the first inner shielding tube in sequence and is arranged outside.

[0014] The diameters of the first inner shielding tube and the second inner shielding tube are the same, and the length of the second inner shielding tube is less than that of the first inner shielding tube.

[0015] Further, the protective soil core has a circular truncated cone structure, and the upper end of the outer shielding tube is provided with external threads for cooperating with a sample making mold.

[0016] The application further provides a preparation method of the loading assembly for the spherical wave loading test sample of the soil material.

[0017] Step 1: preparing the protective soil core by a protective soil core preparation device;

[0018] Step 2: fixing one end of the detonating cord on the explosive ball, and sequentially passing the other end of the detonating cord from bottom to top through the semicircular notch of the protective soil core, the inner shielding tube and the outer side of the outer shielding tube, and fixing the explosive ball in the semicircular notch of the protective soil core;

[0019] Step 3: sleeving the outer shielding tube outside the inner shielding tube, and keeping the lower end of the outer shielding tube connected with the upper surface of the protective soil core, to complete the preparation of the loading assembly.

[0020] Further, in step 1, the protective soil core preparation device comprises an upper pressing piece, a lower pressing piece and a plug column.

[0021] The upper pressing piece comprises an upper pressing head and an upper mold sleeve, the middle part of the upper mold sleeve is provided with an upper pressing through hole matched with the shape of the lower end of the protective soil core, the lower end of the upper pressing head is provided with an upper pressing protrusion matched with the shape and size of the upper pressing through hole, and the middle part of the lower end of the upper pressing protrusion is coaxially provided with a hemisphere with the same size as the explosive ball.

[0022] The lower pressing piece comprises a lower mold sleeve, a lower pressing head and a gasket ring, the middle part of the lower mold sleeve is axially provided with a preparation cavity and a clamping hole which are sequentially arranged and communicated, the structure and size of the preparation cavity are the same as those of the protective soil core when it is placed upside down, the upper end surface of the lower mold sleeve is coaxially connected with the upper mold sleeve, the gasket ring is coaxially arranged at the lower end surface of the lower mold sleeve, and the middle part of the lower pressing head is provided with a clamping head matched with the clamping hole, and the axial length of the clamping head is the sum of the axial lengths of the gasket ring and the clamping hole.

[0023] The clamping head of the lower pressing head is arranged in the clamping hole after passing through the middle part of the gasket ring and can slide along the clamping hole, and the middle part of the clamping head is provided with a blind hole; the hemisphere on the upper pressing protrusion of the upper pressing head is coaxially arranged in the preparation cavity after passing through the upper pressing through hole, and the upper pressing protrusion can slide along the upper pressing through hole, and the middle part of the upper mold sleeve is provided with a through hole coaxial with the blind hole and with the same inner diameter as the inner shielding tube.

[0024] The blind hole is used for placing the inner shielding tube, and the plug column is used for being inserted into the inner shielding tube after passing through the through hole from top to bottom, so as to prevent the inner shielding tube from being blocked when the protective soil core is prepared.

[0025] Further, the height of the gasket ring is 1 / 3-1 / 2 of the height of the protective soil core.

[0026] Further, the lower end surface of the upper mold sleeve is provided with an annular boss, the upper end surface of the lower mold sleeve is provided with an annular groove matched with the annular boss, and the annular boss is arranged in the annular groove.

[0027] Further, the upper die sleeve and the lower die sleeve are fixed by at least two screws;

[0028] The upper die sleeve is uniformly provided with a plurality of stepped holes corresponding to the number of screws, and the lower die sleeve is uniformly provided with a plurality of mounting holes corresponding to the number of stepped holes, and one end of the screw is screwed with the corresponding mounting hole after passing through the stepped hole.

[0029] Further, step 1 is specifically:

[0030] 1.1 Put the inner shielding tube into the blind hole of the lower pressing head, and put the plug column into the inner shielding tube;

[0031] 1.2 Install the grommet, lower die sleeve and upper die sleeve on the lower pressing head in sequence;

[0032] 1.3 Pour the required soil-sand mixture into the upper pressing hole of the upper die sleeve, install the upper pressing head, and make the plug column pass through the through hole in the center of the upper pressing head;

[0033] 1.4 Put the protective soil core preparation device with soil-sand mixture and inner shielding tube into the pressing equipment for pressing until the upper pressing head and the upper die sleeve are completely fitted to stop pressing;

[0034] 1.5 Remove the upper pressing head, lower pressing head, grommet and plug column in sequence, then install the lower pressing head in the lower die sleeve, pressurize the lower pressing head by using the pressing equipment, and eject the protective soil core from the lower die sleeve to obtain the protective soil core.

[0035] The application further provides a loading system for a spherical wave loading sample of soil material, which is characterized in that the loading system comprises the loading assembly for the spherical wave loading sample of soil material and a particle velocity meter.

[0036] The particle velocity meter is arranged in the sample to be measured and is sleeved outside the loading assembly.

[0037] Compared with the prior art, the application has the following beneficial technical effects:

[0038] 1. The loading assembly for the spherical wave loading sample of soil material provided by the application is used for preparing a protective soil core for an explosive ball in a spherical wave test, the density and other parameters of the protective soil core are consistent with those of the sample to be measured after being formed, the shape of the sample to be measured is not changed in the pressing process of sample preparation, the explosive ball is well protected, the safety in the sample preparation process is ensured, and the shape of the explosive ball is not changed.

[0039] 2. The core loading component obtained by the preparation method of the present invention has half of the explosive ball exposed at its bottom, and a hemispherical groove of the same size can be pressed in the center of the sample to be tested, thereby realizing the positioning of the explosive ball in the horizontal plane; in addition, the top of the outer shielding tube has external threads, which can be used with the sample preparation mold to realize the vertical positioning of the explosive ball, further ensuring the safety of the sample preparation process and that the position of the explosive ball does not change.

[0040] 3. The soil core preparation device used in the preparation method provided by the present invention adopts a frustum-shaped cavity and a gasket design, which can facilitate the demolding of soil core samples, thereby ensuring that their shape and other parameters are not damaged during the demolding process.

[0041] 4. The soil core preparation device used in the preparation method provided by the present invention pre-embeds a section of inner shielding tube into the protective soil core, which maximizes the shielding of interference generated by the explosion of the soft detonating cord, and makes it easier to connect with the outer shielding tube. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the loading assembly (including the sample to be tested) used for spherical wave loading of soil material in an embodiment of the present invention.

[0043] Figure 2 This is a cross-sectional view of the soil core preparation device used in the embodiments of the present invention;

[0044] Figure label:

[0045] 1. Detonating cord; 2. Outer shielding tube; 3. First inner shielding tube; 4. Second inner shielding tube; 5. Protective soil core; 6. Explosive ball; 7. Particle velocity meter; 8. Upper pressure head; 9. Plug; 10. Upper mold sleeve; 11. Inner shielding tube; 12. Lower mold sleeve; 13. Washer ring; 14. Lower pressure head; 15. Sample to be tested. Detailed Implementation

[0046] This invention proposes a loading assembly for spherical wave loaded specimens of soil materials, such as... Figure 1 As shown, it includes a detonating cord 1, an outer shielding tube 2, a protective soil core 5, an inner shielding tube 11, and an explosive ball 6.

[0047] The inner shielding tube 11 includes a first inner shielding tube 3 and a second inner shielding tube 4. The length of the second inner shielding tube 4 is less than the length of the first inner shielding tube 3. The density of the protective soil core 5 is the same as the density of the sample 15 to be tested.

[0048] The protective soil core 5 has a frustum-shaped structure. A semi-circular notch, compatible with the explosive ball 6, is located in the center of the larger diameter end. A downward-facing through hole is coaxially arranged in the center of the smaller diameter end. The lower end of the through hole is tangent to the semi-circular notch. The inner diameter of the through hole matches the outer diameter of the second inner shielding tube 4. The lower end of the second inner shielding tube 4 is positioned within the through hole with an interference fit, and the lower end of the second inner shielding tube 4 is flush with the lower end of the through hole. The upper end of the lower end of the second inner shielding tube 4 protrudes through the through hole and is positioned outside the protective soil core 5. A coaxial arrangement is also present inside the first inner shielding tube 3. At the upper end of the second inner shielding tube 4, the outer shielding tube 2 is sleeved outside the first inner shielding tube 3 and the second inner shielding tube 4, and there is a gap between it and the second inner shielding tube 4 and the first inner shielding tube 3. The lower end of the outer shielding tube 2 is set on the upper end surface of the protective soil core 5, and the lower end of the outer shielding tube 2 is lower than the upper end of the first inner shielding tube 3. The explosive ball 6 is set in the semi-circular notch. The lower end of the detonating cord 1 is connected to the explosive ball 6, and the upper end passes through the second inner shielding tube 4 and the first inner shielding tube 3 in sequence, and is placed outside the first inner shielding tube 3.

[0049] The inner diameter and outer diameter of the first inner shielding tube 3 and the second inner shielding tube 4 are the same.

[0050] Dividing the inner shielding tube 11 into two sections, one long and one short, allows the shorter section to be directly embedded into the soil core during core fabrication, resulting in a more secure connection between the shorter section and the soil core. If the section is not divided, the longer shielding tube would increase the difficulty of core fabrication and raise the risk of damage during demolding.

[0051] The outer shielding tube 2 can shield the explosive load generated by the detonating cord 1, reducing interference with the test. The upper end of the outer shielding tube 2 is provided with external threads.

[0052] Based on the above structure, the present invention proposes a protective soil core preparation device, such as... Figure 2 As shown, it includes an upper pressing component, a lower pressing component, and a plunger 9. The upper pressing component includes an upper pressing head 8 and an upper die sleeve 10, and the lower pressing component includes a lower die sleeve 12, a lower pressing head 14, and a washer ring 13.

[0053] The upper mold sleeve 10 is a cylindrical ring (i.e., the middle of the cylinder is provided with an upper pressure through hole). The inner diameter of the ring is the same as the diameter of the large diameter end of the protective soil core 5. At least two through first step holes are opened on the circumference of the upper mold sleeve 10. An annular boss is provided on the outer periphery of the lower end face of the upper mold sleeve 10.

[0054] The lower mold sleeve 12 is a cylinder. The upper end face of the lower mold sleeve 12 is provided with an annular groove that matches the annular boss. Multiple mounting holes are provided on its circumference, which are in the same position and number as the first step hole on the circumference of the upper mold sleeve 10. The annular boss can be placed in the annular groove, and then screws or bolts can be threaded through the first step hole and connected to the mounting hole, thereby fixing the upper mold sleeve 10 and the lower mold sleeve 12 together.

[0055] A preparation cavity and a clamping hole are coaxially arranged in the center of the lower die sleeve 12, the shape and size of the preparation cavity are the same as those of the protective soil core 5 when it is inverted, and the diameter of the clamping hole is the same as that of the small-diameter end of the protective soil core 5;

[0056] The lower end of the upper pressing head 8 is provided with an upper pressing protrusion which is matched with the shape and size of the upper pressing through hole, and a hemispherical head is coaxially arranged in the middle of the lower end of the upper pressing protrusion and has the same size as the explosive ball 6;

[0057] The gasket ring 13 is coaxially arranged on the lower end surface of the lower die sleeve 12, and the middle part of the lower pressing head 14 is provided with a clamping head which is matched with the clamping hole, and the axial length of the clamping head is the sum of the axial lengths of the gasket ring 13 and the clamping hole;

[0058] The clamping head of the lower pressing head 14 is arranged in the clamping hole after passing through the middle part of the gasket ring 13 and can slide along the clamping hole, a blind hole is arranged in the middle of the clamping head, the diameter of the blind hole is 0.1mm larger than the outer diameter of the second inner shielding tube 4, and the length of the blind hole is the same as the length of the clamping head; the upper pressing protrusion of the upper pressing head 8 is arranged in the preparation cavity after passing through the upper pressing through hole, the hemispherical head on the upper pressing protrusion is coaxially arranged in the preparation cavity, the upper pressing protrusion can slide along the upper pressing through hole, and a through hole which is coaxial with the blind hole and has the same inner diameter as the inner layer shielding tube 11 is arranged in the middle of the upper die sleeve 10, and the diameter of the through hole is 0.1mm larger than that of the plug column 9;

[0059] The blind hole is used for placing the second inner shielding tube 4, and the plug column 9 is used for being inserted into the second inner shielding tube 4 after passing through the through hole from top to bottom, so as to prevent the second inner shielding tube 4 from being blocked when the protective soil core is prepared.

[0060] The thickness of the gasket ring 13 is 1 / 3-1 / 2 of the height of the protective soil core 5 to be prepared, and the thickness of the gasket ring 13 is the height of the protective soil core 5 to be ejected during demolding; if the thickness is too small, the demolding of the protective soil core 5 may not be sufficient, and it is difficult to take out; if the thickness is too large, the protective soil core 5 may fall off and be easily damaged.

[0061] Based on the above structure, the application provides a preparation method of a loading assembly for a spherical wave loading sample of soil material, the diameter of the explosive ball 6 used in the embodiment is 5mm, the diameter of the detonating cord 1 is 1mm, the outer diameter of the first inner shielding tube 3 and the second inner shielding tube 4 is 2mm, the inner diameter is 1.2mm, the outer diameter of the outer layer shielding tube 2 is 4mm, and the inner diameter is 2.5mm; the radii of the upper and lower end surfaces of the circular truncated cone-shaped protective soil core 5 to be prepared are 8mm and 10mm respectively, the height is 10mm, the diameter of the central through hole is slightly larger than 2mm, and the diameter of the hemispherical hole at the bottom is 5mm; the total mass of the required soil mixture is 6.1g, and the specific steps are as follows:

[0062] Step 1: preparing the protective soil core by the protective soil core preparation device

[0063] 1.1, Put the second inner shielding tube 4 into the blind hole of the lower pressing head 14, and put the plug column 9 into the second inner shielding tube 4 to prevent the earth sand mixture particles from entering during the manufacturing process;

[0064] 1.2, The installation gasket ring 13 and the lower mold sleeve 12 are coaxially sleeved on the lower pressing head 14 in sequence, and the upper mold sleeve 10 is coaxially bolted on the upper end surface of the lower mold sleeve 12;

[0065] 1.3, Pour 6.1g of earth sand mixture into the inner hole of the upper mold sleeve 10, install the upper pressing head 8, so that the upper pressing protrusion is arranged in the upper pressing through hole, the plug column 9 passes through the through hole in the center of the upper pressing head 8, that is, the through hole in the center of the pressing head, the hemispherical head protruding from the lower end of the pressing head, and the blind hole in the center of the pressing head of the lower mold sleeve 12 is coaxial;

[0066] 1.4, Put the installed protective earth core preparation device into the pressing equipment for pressing, so as to ensure that the stress in the protective earth core 5 is uniform, and stop pressing until the upper pressing head 8 and the upper mold sleeve 10 are completely attached;

[0067] 1.5, Remove the upper pressing head 8, the lower pressing head 14, the gasket ring 13 and the plug column 9 in sequence, then install the lower pressing head 14 in the lower mold sleeve 12, and use the pressing equipment and the lower pressing head 14 to eject the protective earth core 5 to realize demolding and obtain the protective earth core.

[0068] Step 2: The first inner shielding tube 3 is arranged above the second inner shielding tube 4, one end of the detonating cord 1 passes through the first inner shielding tube 3, the second inner shielding tube 4 and the semicircular notch in sequence from top to bottom, and is fixed and pasted on the explosive ball 6, and the detonating cord 1 is pulled until the explosive ball 6 is fixed in the semicircular notch of the protective earth core 5;

[0069] Step 3: The outer shielding tube 2 is sleeved outside the first inner shielding tube 3 and the second inner shielding tube 4, and the lower end of the outer shielding tube 2 is connected with the upper surface of the protective earth core 5, and the preparation of the loading assembly is completed.

[0070] In this embodiment, the connection mode between the components in the loading assembly can adopt gluing.

[0071] Based on the above loading assembly, the application further provides a loading system for a spherical wave loading sample of soil material, which comprises the above loading assembly for the spherical wave loading sample of soil material and a particle velocity meter 7.

[0072] The particle velocity meter 7 is arranged in the sample to be measured 15 and is sleeved outside the loading assembly.

[0073] The use method of the application is as follows:

[0074] The sample 15 to be tested is divided into two layers, after the lower layer is pressed, a semispherical groove with the same diameter as the explosive ball 6 is pressed in the middle of the lower layer, then the loading assembly is arranged on the surface of the lower layer, the explosive ball 6 is kept arranged in the semispherical groove, and is fixed by using double-sided adhesive, the particle velocity meter 7 is sleeved outside the loading assembly, and the particle velocity meter 7 is fixed with the lower layer structure, then the upper layer is continuously pressed until the upper layer is pressed.

[0075] The protective earth core 5 is added in the loading assembly, the explosive ball 6 is better protected, and a positioning interface is provided, so that the safety in the sample preparation process is ensured, the shape and position of the explosive ball are not changed, the sand particles are prevented from piercing the surface of the explosive ball 6, the originally regular spherical shape of the explosive ball 6 is prevented from being damaged, and the safety problem is avoided.

[0076] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A loading assembly for spherical wave loading of a sample of earth material, for placement in a sample (15) to be tested, characterised in that: The loading assembly comprises a detonating cord (1), an outer shielding tube (2), an inner shielding tube (11), a protective soil core (5) and an explosive ball (6); The inner diameter of the inner shielding tube (11) is greater than the diameter of the detonating cord (1), and the density of the protective soil core (5) is the same as that of the sample (15) to be tested; The lower end of the protective soil core (5) is coaxially provided with a semicircular notch matched with the size of the explosive ball (6), and the area above the semicircular notch of the protective soil core (5) is coaxially provided with a through hole communicated with the semicircular notch, the diameter of the through hole is matched with the outer diameter of the inner shielding tube (11), one end of the inner shielding tube (11) is arranged in the through hole, and the other end is located above the protective soil core (5), the outer shielding tube (2) is sleeved outside the inner shielding tube (11) and there is a gap between the two, the lower end of the outer shielding tube (2) is arranged on the protective soil core (5), and the upper end is located outside the sample (15) to be tested; The upper half of the explosive ball (6) is arranged in the semicircular notch, the lower end of the detonating cord (1) is connected with the explosive ball (6), and the upper end of the detonating cord (1) is arranged outside after passing through the inner shielding tube (11), and the lower half of the explosive ball (6) is arranged in the sample of the soil material to be tested.

2. The loading assembly for the spherical wave loading test of the soil material according to claim 1, wherein: The inner shielding tube (11) comprises a first inner shielding tube (3) and a second inner shielding tube (4) which are coaxially arranged and the inner diameter of which is greater than that of the detonating cord (1); One end of the second inner shielding tube (4) is arranged in the through hole, and the other end is located in the outer shielding tube (2), one end of the first inner shielding tube (3) is located in the outer shielding tube (2) and is communicated with the second inner shielding tube (4), and the other end passes out of the upper end of the outer shielding tube (2); the other end of the detonating cord (1) is sequentially arranged outside after passing through the second inner shielding tube (4) and the first inner shielding tube (3); The diameters of the first inner shielding tube (3) and the second inner shielding tube (4) are the same, and the length of the second inner shielding tube (4) is less than that of the first inner shielding tube (3).

3. The loading assembly for the spherical wave loading test of the soil material according to claim 2, wherein: The protective soil core (5) is in a circular truncated cone structure, and the upper end of the outer shielding tube (2) is provided with external threads for cooperation with a sample preparation mold.

4. A method for manufacturing a loading assembly for a spherical wave loading test specimen of a soil material according to any one of claims 1 to 3, characterized in that, The preparation method comprises the following steps: Step 1: preparing the protective soil core by a protective soil core preparation device; Step 2: fixing one end of the detonating cord (1) on the explosive ball (6), and sequentially arranging the other end from the lower end to the upper end through the semicircular notch of the protective soil core, the inner shielding tube (11) and outside, and fixing the explosive ball (6) in the semicircular notch of the protective soil core (5); Step 3: sleeving the outer shielding tube (2) outside the inner shielding tube (11), and keeping the lower end of the outer shielding tube (2) connected with the upper surface of the protective soil core (5) to complete the preparation of the loading assembly.

5. The preparation method of the loading assembly for the spherical wave loading test of the soil material according to claim 4, wherein: In step 1, the protective soil core preparation device comprises an upper pressing piece, a lower pressing piece and a plug column (9). The upper pressing member comprises an upper pressing head (8) and an upper die sleeve (10), the upper die sleeve (10) is provided with an upper pressing through hole in the middle part, which is matched with the shape of the lower end of the protective soil core (5), the lower end of the upper pressing head (8) is provided with an upper pressing protrusion, which is matched with the shape and size of the upper pressing through hole, and a semisphere with the same size as the explosive ball (6) is coaxially arranged in the middle part of the lower end of the upper pressing protrusion; The lower pressing member comprises a lower die sleeve (12), a lower pressing head (14) and a gasket ring (13), the lower die sleeve (12) is provided with a preparation cavity and a clamping hole which are arranged in sequence and communicated in the axial direction, the structure and size of the preparation cavity are the same as those of the protective soil core (5) when it is inverted, the upper end surface of the lower die sleeve (12) is coaxially connected with the upper die sleeve (10), the gasket ring (13) is coaxially arranged on the lower end surface of the lower die sleeve (12), and the middle part of the lower pressing head (14) is provided with a clamping head which is matched with the clamping hole, and the axial length of the clamping head is the sum of the axial lengths of the gasket ring (13) and the clamping hole; The clamping head of the lower pressing head (14) is arranged in the clamping hole after passing through the middle part of the gasket ring (13) and can slide along the clamping hole, and a blind hole is arranged in the middle part of the clamping head; the semisphere on the upper pressing protrusion of the upper pressing head (8) is coaxially arranged in the preparation cavity after passing through the upper pressing through hole, and the upper pressing protrusion can slide along the upper pressing through hole, and the middle part of the upper die sleeve (10) is provided with a through hole which is coaxial with the blind hole and has the same inner diameter as the inner layer shielding pipe (11); The blind hole is used for arranging the inner layer shielding pipe (11), and the plug column (9) is used for being inserted into the inner layer shielding pipe (11) after passing through the through hole from top to bottom, so that the inner layer shielding pipe (11) is prevented from being blocked during preparation of the protective soil core.

6. The preparation method of the loading assembly for the spherical wave loading sample of soil material according to claim 5, wherein: The height of the gasket ring (13) is 1 / 3-1 / 2 of the height of the protective soil core (5).

7. The preparation method of the loading assembly for the spherical wave loading sample of soil material according to claim 6, wherein: An annular boss is arranged on the lower end surface of the upper die sleeve (10), an annular groove which is matched with the annular boss is arranged on the upper end surface of the lower die sleeve (12), and the annular boss is arranged in the annular groove.

8. The preparation method of the loading assembly for the spherical wave loading sample of soil material according to any one of claims 5-7, wherein: The upper die sleeve (10) and the lower die sleeve (12) are fixed by at least two screws; A plurality of stepped holes which are the same in number as the screws and one-to-one corresponding are uniformly arranged on the circumference of the upper die sleeve (10), a plurality of mounting holes which are the same in number as the stepped holes and one-to-one corresponding are uniformly arranged on the circumference of the lower die sleeve (12), and one end of the screw passes through the stepped hole and is threadedly connected with the corresponding mounting hole.

9. The method according to claim 8, wherein Step 1 is specifically: 1.1 The inner layer shielding pipe (11) is arranged in the blind hole of the lower pressing head (14), and the plug column (9) is arranged in the inner layer shielding pipe (11); 1.2 The gasket ring (13), the lower die sleeve (12) and the upper die sleeve (10) are sequentially arranged on the lower pressing head (14); 1.3 Pour the required soil-sand mixture into the upper pressing hole of the upper die sleeve (10), and install the upper pressing head (8) so that the plug column (9) passes through the through hole in the center of the upper pressing head (8); 1.4 Put the protective soil core preparation device with the soil-sand mixture and the inner shielding tube (11) into the pressing equipment for pressing until the upper pressing head (8) completely matches the upper die sleeve (10) to stop pressing; 1.5 Remove the upper pressing head (8), the lower pressing head (14), the gasket ring (13) and the plug column (9) in sequence, then install the lower pressing head (14) in the lower die sleeve (12), and pressurize the lower pressing head (14) by using the pressing equipment to eject the protective soil core (5) from the lower die sleeve (12) to obtain the protective soil core.

10. A loading system for spherical wave loading of a sample of soil material, characterized by: The loading assembly and the particle velocity meter (7) for loading the spherical wave test sample of the soil material according to any one of claims 1-3; The particle velocity meter (7) is arranged in the sample (15) to be tested and is sleeved outside the loading assembly.

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