Concrete water permeability resistance test device and test method

Abstract

The embodiment of the present application provides a concrete water permeability test device and test method, which are used to test the water permeability of a cylindrical concrete specimen with a water injection cavity. The concrete water permeability test device includes: a water pressure loading device and an external load loading device; the water pressure loading device includes an automatic pressurizing machine, and a first cover plate assembly and a second cover plate assembly sealed and connected to both ends of the concrete specimen, and the first cover plate assembly has a water injection channel; the external load loading device includes a first clamping plate, a second clamping plate, a guide, a push mechanism, a mounting plate and a displacement sensor; the first clamping plate is fixedly connected to the guide, and the second clamping plate is slidably connected to the guide; the mounting plate is fixedly connected to the guide, and the push mechanism is mounted on the mounting plate. The concrete water permeability test device and test method of the embodiment of the present application can efficiently and accurately test and evaluate the water pressure penetration resistance of the concrete lining of the tunnel under the action of external loads.

Description

Technical Field

[0001] The invention relates to the field of concrete water permeability resistance test, and in particular to a concrete water permeability resistance test device and a test method. Background Art

[0002] The current concrete water permeability test is based on Darcy's law of fluid mechanics, which regards concrete as a porous solid material and uses the permeability coefficient to evaluate the concrete's impermeability, which is called the permeability coefficient method. The permeability coefficient method refers to a method of studying the permeability of concrete by using the principle that the fluid gradually penetrates from one end to the other through the pores of the object under certain pressure conditions. In my country, in order to take into account the convenience of actual engineering applications, the qualitative impermeability label method is mainly used to evaluate the impermeability of concrete. Specifically, six standard impermeability test pieces (upper bottom surface 175mm, lower bottom surface 185mm) are made according to the specifications, and after sealing the sides, they are placed on the impermeability testing machine for step-by-step pressurization. Each level of water pressure is stable for 8 hours until three of the six test pieces leak and the test is stopped, and the impermeability grade is calibrated according to the water pressure at the time of leakage. In addition, the water seepage height method and the relative permeability coefficient method can also be used. The test method is similar to the impermeability label method, and both can directly or indirectly express the approximate relative permeability coefficient.

[0003] However, the relevant test methods cannot efficiently and accurately test and evaluate the water pressure penetration resistance of the tunnel's concrete lining under external loads. Summary of the invention

[0004] In view of this, the main purpose of the embodiments of the present application is to provide a concrete water permeability resistance testing device and testing method that can efficiently and accurately test and evaluate the water pressure penetration resistance of the concrete lining of a tunnel under external loads.

[0005] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0006] An embodiment of the present application provides a concrete water permeability resistance test device, which is used to perform a water permeability resistance test on a cylindrical concrete specimen, wherein the concrete specimen has a water injection cavity that penetrates the concrete specimen along the axial direction, and includes:

[0007] A hydraulic loading device, the hydraulic loading device comprising an automatic pressurizing machine, and a first cover plate assembly and a second cover plate assembly respectively connected to both ends of the concrete specimen in a sealed manner, the first cover plate assembly having a water injection channel for connecting the automatic pressurizing machine and the water injection cavity;

[0008] An external load loading device, the external load loading device includes a first clamping plate, a second clamping plate, a guide member, a pushing mechanism, a mounting plate and a displacement sensor; the first clamping plate is fixedly connected to the guide member, the second clamping plate is slidably connected to the guide member, the first clamping plate and the second clamping plate are used to clamp the concrete specimen from both radial sides of the concrete specimen; the mounting plate is fixedly connected to the guide member and is located on the side of the second clamping plate away from the first clamping plate, the pushing mechanism is installed on the mounting plate, and the telescopic pushing part of the pushing mechanism faces the second clamping plate; the displacement sensor is connected to the first clamping plate and the second clamping plate, and is used to detect the displacement of the second clamping plate during the process of the pushing mechanism pushing the second clamping plate.

[0009] In one embodiment, the first cover plate assembly includes a first cover plate having the water injection channel, and a first sealing ring arranged on one side of the first cover plate, wherein the first sealing ring is located around the water outlet of the water injection channel; the first sealing ring is used to seal and contact with the end face of one end of the concrete specimen;

[0010] The second cover plate assembly includes a second cover plate and a second sealing ring arranged on one side of the second cover plate; the second sealing ring is used for sealing contact with the end surface of the other end of the concrete specimen.

[0011] In one embodiment, one side of the first cover plate has a first positioning groove for matching with one end of the concrete specimen, the water injection channel is communicated with the first positioning groove, and the first sealing ring is disposed in the first positioning groove;

[0012] One side of the second cover plate has a second positioning groove for matching with the other end of the concrete specimen, and the second sealing ring is arranged in the second positioning groove.

[0013] In one embodiment, the first cover plate assembly includes a first cover plate, the water inlet of the water injection channel is arranged on the side wall of the first cover plate, and the water outlet of the water injection channel is arranged on an end surface of one side of the first cover plate.

[0014] In one embodiment, the water injection channel includes a threaded connection section and an extension section connected to one end of the threaded connection section, the opening of the threaded connection section away from the end of the extension section is the water inlet, and the opening of the extension section away from the end of the threaded connection section is the water outlet.

[0015] In one embodiment, the first cover plate assembly is firmly connected to the second cover plate assembly.

[0016] In one embodiment, a portion of the structure of the second clamping plate protrudes outward to form an abutment boss; when the concrete specimen is clamped between the first clamping plate and the second clamping plate, the abutment boss abuts against the concrete specimen.

[0017] In one embodiment, the guide member is a pull rod, and the first clamping plate and the second clamping plate are both inserted into the pull rod.

[0018] In one embodiment, the number of the pull rods is two, the two pull rods are arranged in parallel and spaced apart, and a specimen accommodating space is formed between the two pull rods;

[0019] One of the two pull rods is inserted through one end of the first clamping plate and the second clamping plate, and the other of the two pull rods is inserted through the other end of the first clamping plate and the second clamping plate.

[0020] In one embodiment, the two pull rods are arranged in parallel and spaced apart in the vertical direction, the first cover plate assembly comprises a first cover plate, the first cover plate has a first loading avoidance opening and a second loading avoidance opening, and the second cover plate has a third loading avoidance opening and a fourth loading avoidance opening;

[0021] When the concrete specimen is clamped between the first clamping plate and the second clamping plate, and the two ends of the water injection cavity are respectively sealed and connected to the first cover plate assembly and the second cover plate assembly, the first loading avoidance port and the third loading avoidance port avoid the first clamping plate, and the second loading avoidance port and the fourth loading avoidance port avoid the second clamping plate.

[0022] Another embodiment of the present application further provides a concrete water permeability resistance test method, which is implemented using the concrete water permeability resistance test device described above, and the method comprises the following steps:

[0023] Divide a plurality of cylindrical concrete specimens with water injection cavities into three groups, the three groups of concrete specimens are respectively a first group of specimens, a second group of specimens and a third group of specimens, the concrete specimens in the first group of specimens are concrete specimens one, the concrete specimens in the second group of specimens are concrete specimens two, and the concrete specimens in the third group of specimens are concrete specimens three;

[0024] The first cover plate assembly and the second cover plate assembly are respectively sealed and connected to the two ends of the water injection cavity of the concrete specimen one; the water reaching a preset water pressure is loaded into the water injection cavity of the concrete specimen one by the automatic pressurizing machine until the water seeps out from the outer wall of the concrete specimen one; according to the loading data recorded by the automatic pressurizing machine during the water pressure loading process, the variation law of the concrete permeability coefficient under stress-free action is obtained; wherein the loading data includes the loading water amount corresponding to different time points of the automatic pressurizing machine during the water pressure loading process;

[0025] The second concrete specimen is clamped between the first clamping plate and the second clamping plate, and the second clamping plate is pushed by the pushing mechanism until the second concrete specimen is subjected to compression and bending failure; in the process of the pushing mechanism pushing the second clamping plate, the magnitude of the pushing force loaded by the pushing mechanism and the displacement of the second clamping plate under the action of different magnitudes of pushing forces are recorded, and the variation law of the elastic modulus under the action of no water pressure is obtained according to the obtained pushing force loaded by the pushing mechanism and the corresponding displacement of the second clamping plate, and the peak value of the pushing force loaded by the pushing mechanism is determined;

[0026] The two ends of the water injection cavity of the concrete specimen three are sealed and connected to the first cover plate assembly and the second cover plate assembly respectively, and the sealed concrete specimen three is clamped between the first clamping plate and the second clamping plate; within a preset time, the water reaching a preset water pressure is loaded into the water injection cavity of the concrete specimen three by using the automatic pressurizing machine, and the second clamping plate is pushed by the pushing mechanism, wherein the maximum value of the pushing force loaded by the pushing mechanism is less than the peak value of the pushing force loaded by the pushing mechanism obtained in the test on the concrete specimen two; according to the loading data recorded by the automatic pressurizing machine during the water pressure loading process, the variation law of the concrete permeability coefficient under the action of the external load is obtained; wherein the loading data includes the amount of water loaded by the automatic pressurizing machine at different time points during the water pressure loading process;

[0027] The obtained variation law of the concrete permeability coefficient under the external load is compared with the variation law of the concrete permeability coefficient under the stress-free condition to determine the influence of concrete mechanical damage under the external load on concrete permeability.

[0028] The embodiment of the present application provides a concrete water permeability resistance test device and test method. By using a water pressure loading device and an external load loading device to conduct a water permeability resistance test on a cylindrical concrete specimen with a water injection cavity, the anti-permeability performance of the concrete lining of the tunnel under different external loads and water pressures can be analyzed, and then the water pressure penetration resistance performance of the concrete lining of the tunnel under the action of external loads can be efficiently and accurately tested and evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A front view of a concrete water permeability resistance test device provided by an embodiment of the present application, showing a concrete test piece, and in order to show the matching relationship between the first clamping plate, the second clamping plate and the concrete test piece, a part of the bolts connecting the first clamping plate and the second clamping plate are omitted in the figure;

[0030] Figure 2 for Figure 1 A top view of

[0031] Figure 3 for Figure 1 Left view of;

[0032] Figure 4 for Figure 1 Schematic diagram of the connection relationship between the first cover plate assembly, the second cover plate assembly and the concrete specimen shown in ;

[0033] Figure 5 for Figure 1 A schematic structural diagram of the first splint shown in ;

[0034] Figure 6 for Figure 1 A schematic diagram of the structure of the second splint shown in ;

[0035] Figure 7 for Figure 1 A schematic structural diagram of the first cover plate assembly shown in ;

[0036] Figure 8 for Figure 7 AA section view in;

[0037] Fig. 9 for Figure 1 A schematic structural diagram of the second cover plate assembly shown in ;

[0038] Fig.10 for Fig. 9 BB section view in;

[0039] Fig.11 A flowchart of a concrete water permeability resistance test method provided in one embodiment of the present application.

[0040] Reference numerals:

[0041] Concrete water permeability resistance test device 100; hydraulic pressure loading device 110; first cover plate assembly 111; first cover plate 1111; first positioning groove 1111a; first loading avoidance opening 1111b; second loading avoidance opening 1111c; first sealing ring 1112; water injection channel 111a; water inlet 111b; water outlet 111c; threaded connection section 111d; extension section 111e; second cover plate assembly 112; first Second cover plate 1121; second positioning groove 1121a; third loading avoidance opening 1121b; fourth loading avoidance opening 1121c; second sealing ring 1122; bolt 113; external load loading device 120; first clamping plate 121; second clamping plate 122; abutment boss 1221; guide member 123; pushing mechanism 124; telescopic pushing part 1241; mounting plate 125; concrete specimen 200; water injection chamber 200a. DETAILED DESCRIPTION

[0042] It should be noted that, in the absence of conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other, and the detailed description in the specific implementation method should be understood as an explanation of the purpose of the present application and should not be regarded as an improper limitation on the present application.

[0043] In the description of this application, the "vertical direction" orientation or position relationship is based on the attached Figure 1 Regarding the orientation or positional relationship shown, it should be understood that these orientation terms are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0044] An embodiment of the present application provides a concrete water permeability resistance test device 100, which is used to perform a water permeability resistance test on a cylindrical concrete specimen 200. Figures 1 to 4 The concrete specimen 200 has a water injection cavity 200 a that penetrates the concrete specimen 200 along the axial direction. The concrete water permeability resistance testing device 100 includes: a water pressure loading device 110 and an external load loading device 120 .

[0045] The hydraulic loading device 110 includes an automatic pressurizing machine (not shown), and a first cover plate assembly 111 and a second cover plate assembly 112 respectively sealed and connected to both ends of the concrete specimen 200. The first cover plate assembly 111 has a water injection channel 111a for connecting the automatic pressurizing machine and the water injection chamber 200a. That is, after the first cover plate assembly 111 and the second cover plate assembly 112 are respectively sealed and connected to both ends of the water injection chamber 200a, the automatic pressurizing machine can load water into the water injection chamber 200a through the water injection channel 111a.

[0046] The external load loading device 120 includes a first clamping plate 121, a second clamping plate 122, a guide member 123, a pushing mechanism 124, a mounting plate 125 and a displacement sensor (not shown). The first clamping plate 121 is fixedly connected to the guide member 123, and the second clamping plate 122 is slidably connected to the guide member 123. The first clamping plate 121 and the second clamping plate 122 are used to clamp the concrete specimen 200 from both sides of the radial direction of the concrete specimen 200. The mounting plate 125 is fixedly connected to the guide member 123 and is located on the side of the second clamping plate 122 away from the first clamping plate 121. The pushing mechanism 124 is mounted on the mounting plate 125, and the telescopic pushing portion of the pushing mechanism 124 faces the second clamping plate 122. That is, when the concrete specimen 200 is clamped between the first clamping plate 121 and the second clamping plate 122, the pushing mechanism 124 pushes the second clamping plate 122, so that the first clamping plate 121 and the second clamping plate 122 can apply radial pressure P to the concrete specimen 200, that is, the concrete specimen 200 can be loaded with an external load through the pushing mechanism 124. The displacement sensor is connected to the first clamping plate 121 and the second clamping plate 122, and is used to detect the displacement of the second clamping plate 122 when the pushing mechanism 124 pushes the second clamping plate 122.

[0047] Specifically, the geometric dimensions of the cylindrical concrete specimen 200 selected in this embodiment are an inner diameter of 75 mm, an outer diameter of 150 mm, and a height of 150 mm. In other implementations, the geometric dimensions of the concrete specimen 200 can be adjusted as needed.

[0048] The automatic pressurizing machine can maintain the water pressure at a preset water pressure when loading water into the water injection chamber 200a of the concrete specimen 200, so as to avoid the water pressure drop in the water injection chamber 200a during the process of penetrating into the side wall of the concrete specimen 200, thereby affecting the test results. Specifically, the automatic pressurizing machine of this embodiment can load and stabilize the water pressure in the range of 0-15MPa. In addition, the automatic pressurizing machine can also automatically record the amount of loaded water corresponding to different time points during the water pressure loading process, so as to facilitate the collection of test data.

[0049] The pushing mechanism 124 can be a mechanism with a pushing function such as a jack, a hydraulic cylinder, etc. In this embodiment, the guide member 123 and the mounting plate 125 are designed according to the strength requirement of a maximum load of 30t.

[0050] The concrete water permeability test described in this embodiment simplifies the loading mode used in the test according to the load mode of the tunnel. Specifically, the load on the concrete lining of the tunnel is mainly divided into three parts: vertical pressure, horizontal pressure, and base reaction force, wherein the vertical pressure includes the pressure generated by the deadweight of the overlying soil, the arching effect, and the water pressure, and the horizontal pressure is obtained by multiplying the vertical pressure by a lateral pressure coefficient less than 1. For different stratum conditions, the lateral pressure coefficient is different, but all are less than 1. In addition, since the lateral soil pressure can constrain the deformation of the stratum structure, it is actually beneficial to the structural stress, and the concrete water permeability test described in this embodiment mainly considers the adverse effect of external loads on the permeability of the concrete lining, therefore, the horizontal pressure can be ignored. The base reaction force is composed of vertical pressure and structural deadweight. It can be seen that among the vertical pressure, horizontal pressure, and base reaction force on the concrete lining, the vertical pressure is the main part of the external load on the concrete lining, and is also the main factor causing the concrete lining to crack during the use of the tunnel.

[0051] See also Figure 1 In order to ensure the efficiency and economy of the test process, the concrete water permeability resistance test described in this embodiment ignores the horizontal load on the concrete lining, and adopts a set of radial pressures P to simulate the load characteristics of the concrete lining in the vertical direction. Specifically, the first clamping plate 121 fixedly connected to the guide member 123 can prevent the concrete specimen 200 from moving when the pushing mechanism 124 pushes the second clamping plate 122, thereby enabling the first clamping plate 121 and the second clamping plate 122 to apply radial pressure P to the concrete specimen 200, thereby simulating the load characteristics of the concrete lining in the vertical direction.

[0052] For traditional test methods such as permeability coefficient method and impermeability number method, there are several obvious limitations:

[0053] 1. The traditional test method is to use a solid cylindrical specimen for permeability test. Water penetrates upward from the bottom of the solid cylindrical specimen, that is, the permeability surface of the solid cylindrical specimen is the bottom of the solid cylindrical specimen. The penetration depth is measured during the penetration process, and the permeability coefficient is calculated using the penetration depth. This test method often requires more than one week of pressurization time, which is long and inefficient, and often no obvious permeability phenomenon occurs. In addition, affected by the hydration process of concrete, the test results have large errors;

[0054] 2. The traditional test method requires a ruler to measure the water penetration height. When the water seepage is very small, the water penetration height is very small, and the ruler will cause a large error when measuring;

[0055] 3. The traditional test method is to measure the water seepage of concrete in the final state by splitting the specimen, etc. However, this test method cannot obtain the relationship between the water seepage and time, nor can it reflect the change law of concrete permeability over time. Therefore, the conclusions obtained by using the traditional test method have certain limitations;

[0056] 4. As the tensile strength of concrete is extremely low, it is often in a working state with cracks during the actual service of the material. Under the action of external water pressure, these cracks will become the main channels for water to penetrate into the concrete. Traditional test methods cannot take into account the crack damage phenomenon caused by concrete materials in the actual working process, so it is impossible to measure the concrete permeability suitable for actual engineering durability evaluation.

[0057] As for the concrete water permeability test device 100 of the present embodiment, firstly, the water pressure loading device 110 of the present embodiment loads water into the water injection cavity 200a of the concrete specimen 200, that is, the water penetrates from the inner wall of the water injection cavity 200a to the outside. Compared with the method of penetrating water from the bottom of the solid cylindrical specimen upwards adopted in the traditional test method, the test device of the present embodiment changes the penetration direction of the concrete specimen 200 from the original bottom-to-top penetration to the inside-to-out penetration based on the principle that the water pressure is equal in all directions, thereby increasing the hydraulic gradient in the concrete specimen 200. At the same time, since the water seepage surface of the concrete specimen 200 is changed from the bottom surface to the radial side surface, the test device of the present embodiment can not only greatly improve the penetration efficiency and prevent the concrete specimen 200 from being affected by the hydration process, but also ensure that the obvious penetration phenomenon can be observed from the outer wall of the concrete specimen 200, and the accuracy of the test result is high. In addition, in the traditional test method, since the penetration direction of the solid cylindrical specimen is from bottom to top, a large amount of sealing is required on the side of the solid cylindrical specimen. The sealing workload is not only large, but also often causes test failure due to water leakage. In this embodiment, only the first cover plate assembly 111 and the second cover plate assembly 112 need to be sealed with the two ends of the water injection cavity 200a, thereby not only reducing the amount of sealing material used and effectively reducing the difficulty of sealing, but also reducing the possibility of water leakage due to insufficient sealing measures.

[0058] Secondly, since the automatic pressurizing machine can automatically record the amount of water loaded corresponding to different time points during the hydraulic loading process, and the amount of water loaded is actually equivalent to the amount of water seepage of the concrete specimen 200, when the amount of water seepage of the concrete specimen 200 is very small, the amount of water seepage of the concrete specimen 200 can also be known based on the amount of water loaded recorded by the automatic pressurizing machine. The method of obtaining the amount of water seepage is simple and convenient, and the measurement accuracy of the amount of water seepage can be guaranteed. In addition, according to the amount of water loaded corresponding to different time points automatically recorded by the automatic pressurizing machine, the relationship between the amount of water seepage and time can be obtained, and then the law of change of concrete permeability over time can be reflected.

[0059] Finally, since the external load loading device 120 of this embodiment can apply radial pressure P to the concrete specimen 200 to simulate the load characteristics of the concrete lining in the vertical direction, the test device of this embodiment can simulate the cracking phenomenon generated by the concrete material in the actual working process, and then, the concrete permeability suitable for actual engineering durability evaluation can be measured.

[0060] It can be seen that by using the concrete water permeability resistance testing device 100 of this embodiment, the anti-permeability performance of the concrete lining of the tunnel under different external loads and water pressures can be analyzed, and the water pressure penetration resistance performance of the concrete lining of the tunnel under external loads can be efficiently and accurately tested and evaluated.

[0061] See also Figure 1 , Figure 4 , Figures 7 to 10 In this embodiment, the first cover plate assembly 111 includes a first cover plate 1111 having a water injection channel 111a, and a first sealing ring 1112 disposed on one side of the first cover plate 1111, and the first sealing ring 1112 is located around the water outlet 111c of the water injection channel 111a. The first sealing ring 1112 is used to seal with the end surface of one end of the concrete specimen 200. The second cover plate 1121 The second cover plate assembly 112 includes a second cover plate 1121, and a second sealing ring 1122 disposed on one side of the second cover plate 1121. The second sealing ring 1122 is used to seal with the end surface of the other end of the concrete specimen 200.

[0062] Specifically, when the first cover plate assembly 111 and the second cover plate assembly 112 are respectively sealed and connected to the two ends of the concrete specimen 200, the first sealing ring 1112 is sandwiched between the first cover plate 1111 and the end surface of one end of the concrete specimen 200, the water outlet 111c of the water injection channel 111a is connected to the water injection cavity 200a, and the second sealing ring 1122 is sandwiched between the second cover plate 1121 and the end surface of the other end of the concrete specimen 200, thereby, a good sealing effect can be achieved for the water injection cavity 200a. Since the inner diameter of the cylindrical concrete specimen 200 selected in this embodiment is 75mm, the first sealing ring 1112 and the second sealing ring 1122 can both be selected from full-circle sealing rubber rings with an inner diameter of 75mm and a line diameter of 3mm. In other embodiments, sealing rings of other specifications can also be selected as long as they can seal the water injection cavity 200a.

[0063] For further information, see Figure 4 , Figures 7 to 10 In this embodiment, one side of the first cover plate 1111 has a first positioning groove 1111a for cooperating with one end of the concrete specimen 200, the water injection channel 111a is connected to the first positioning groove 1111a, and the first sealing ring 1112 is arranged in the first positioning groove 1111a. One side of the second cover plate 1121 has a second positioning groove 1121a for cooperating with the other end of the concrete specimen 200, and the second sealing ring 1122 is arranged in the second positioning groove 1121a. That is, when the first cover plate assembly 111 and the second cover plate assembly 112 are respectively sealed and connected to the two ends of the water injection cavity 200a, one end of the concrete specimen 200 is located in the first positioning groove 1111a, and the other end of the concrete specimen 200 is located in the second positioning groove 1121a. The first positioning groove 1111a and the second positioning groove 1121a can not only play a role in positioning the concrete specimen 200, but also improve the sealing effect.

[0064] It is understandable that in other embodiments, only the first cover plate 1111 may be provided with the first positioning groove 1111a, and the second cover plate 1121 may not be provided with the second positioning groove 1121a; only the second cover plate 1121 may be provided with the second positioning groove 1121a, and the first cover plate 1111 may not be provided with the first positioning groove 1111a; or the first cover plate 1111 may not be provided with the first positioning groove 1111a, and the second cover plate 1121 may not be provided with the second positioning groove 1121a. In other embodiments, the first cover plate assembly 111 and the second cover plate assembly 112 may also be sealed and connected to both ends of the water injection chamber 200a in other ways, as long as the two ends of the water injection chamber 200a can be sealed.

[0065] In addition, during the test, in order to prevent the first cover plate assembly 111 and the second cover plate assembly 112 from loosening and causing sealing failure, after the first cover plate assembly 111 and the second cover plate assembly 112 are respectively sealed and connected to the two ends of the water injection cavity 200a, the first cover plate assembly 111 and the second cover plate assembly 112 can also be fastened and connected, for example, see Figures 1 to 3 In this embodiment, six bolts 113 are used to fasten the first cover plate 1111 and the second cover plate 1121. The specification of the bolts 113 may be M16×200. In other embodiments, the number and specification of the bolts 113 may be adjusted as needed. In other embodiments, the first cover plate assembly 111 and the second cover plate assembly 112 may not be fastened together.

[0066] See also Figure 1 , Figure 3 , Figure 4 , Figure 7 and Figure 8 In this embodiment, the water inlet 111b of the water injection channel 111a is arranged on the side wall of the first cover plate 1111, and the water outlet 111c of the water injection channel 111a is arranged on the end surface of one side of the first cover plate 1111. That is to say, when the automatic pressurizing machine is connected to the water inlet 111b of the water injection channel 111a, the water loaded by the automatic pressurizing machine flows from the water inlet 111b to the water outlet 111c, and flows into the water injection chamber 200a through the water outlet 111c. The water inlet 111b of the water injection channel 111a is arranged on the side wall of the first cover plate 1111, which can facilitate the connection of the water inlet 111b with the automatic pressurizing machine. In other embodiments, the water inlet 111b of the water injection channel 111a can also be arranged on the end surface of one side of the first cover plate 1111, and the water outlet 111c of the water injection channel 111a can be arranged on the end surface of the other side of the first cover plate 1111.

[0067] See also Figure 4 and Figure 8 In this embodiment, the water injection channel 111a includes a threaded connection section 111d and an extension section 111e connected to one end of the threaded connection section 111d. The opening of the threaded connection section 111d away from the end of the extension section 111e is the water inlet 111b, and the opening of the extension section 111e away from the end of the threaded connection section 111d is the water outlet 111c. The threaded connection section 111d can be used for threaded connection with the water outlet end of the automatic pressurizing machine, and can also be used for threaded connection with the adapter, and the adapter is connected to the water outlet end of the automatic pressurizing machine. The provision of the threaded connection section 111d is convenient for connecting the water injection channel 111a with the automatic pressurizing machine, and can also prevent water from overflowing from the connection between the water injection channel 111a and the automatic pressurizing machine during the process of the automatic pressurizing machine loading water into the water injection chamber 200a, thereby ensuring the accuracy of the test results.

[0068] See also Figure 1 and Figure 2 In this embodiment, the guide member 123 is a pull rod, and the first clamping plate 121 and the second clamping plate 122 are arranged on the pull rod, wherein the first clamping plate 121 is fixedly connected to the pull rod, and the second clamping plate 122 can slide on the pull rod. The pull rod has a simple structure and good guiding performance, which is convenient for production and manufacturing and can also save production costs.

[0069] In other embodiments, the guide member 123 may also be other guide structures. For example, the guide member 123 may be a guide rail having a guide surface, and the second clamping plate 122 may slide along the guide surface. Alternatively, the guide member 123 may also be a slide rail having a slide groove, and a portion of the structure of the second clamping plate 122 extends into the slide groove so that the second clamping plate 122 can slide along the slide groove. In short, it is sufficient as long as the second clamping plate 122 can be slidably connected to the guide member 123.

[0070] See also Figure 1 , Figure 5 and Figure 6 In this embodiment, part of the structure of the second clamping plate 122 protrudes outward to form an abutting boss 1221. When the concrete specimen 200 is clamped between the first clamping plate 121 and the second clamping plate 122, the abutting boss 1221 abuts against the concrete specimen 200.

[0071] Specifically, since the second clamping plate 122 can slide along the guide member 123 under the pushing of the pushing mechanism 124, the displacement of the second clamping plate 122 can be ensured to be within a controllable range by providing the abutting boss 1221 on the second clamping plate 122, and the maximum deformation of the concrete specimen 200 can be controlled by controlling the maximum displacement of the second clamping plate 122. For example, refer to Figure 6 In this embodiment, the height H1 of the abutment boss 1221 of the second clamping plate 122 is 10 mm, which means that during the process in which the first clamping plate 121 and the second clamping plate 122 apply radial pressure P to the concrete specimen 200, the maximum allowable displacement of the second clamping plate 122 is 10 mm, and correspondingly, the maximum allowable deformation of the concrete specimen 200 is also 10 mm.

[0072] See also Figure 1, the number of tie rods in this embodiment is two, the two tie rods are arranged in parallel and spaced apart, and a specimen accommodating space is formed between the two tie rods. In this embodiment, the two tie rods are arranged in parallel and spaced apart in the vertical direction, that is, when the concrete specimen 200 is clamped between the first clamping plate 121 and the second clamping plate 122, the two tie rods are actually located at the two ends of the axial direction of the concrete specimen 200, respectively. Therefore, the distance between the two tie rods in this embodiment needs to ensure that at least the concrete specimen 200 can be accommodated after being sealed and connected with the first cover plate assembly 111 and the second cover plate assembly 112. In other embodiments, when the concrete specimen 200 is clamped between the first clamping plate 121 and the second clamping plate 122, the two tie rods can also be located at the radial sides of the concrete specimen 200, respectively. In this case, the distance between the two tie rods only needs to be greater than the outer diameter of the concrete specimen 200. One of the two tie rods is inserted through one end of the first clamping plate 121 and the second clamping plate 122, and the other of the two tie rods is inserted through the other end of the first clamping plate 121 and the second clamping plate 122. Providing two pull rods can ensure that the second clamping plate 122 can slide more smoothly, thereby making it easier for the first clamping plate 121 and the second clamping plate 122 to apply radial pressure P to the concrete specimen 200 .

[0073] In other implementations, the number of pull rods may also be adjusted as needed, as long as at least one pull rod is ensured.

[0074] See also Figure 1 , Figures 7 to 10 In this embodiment, the first cover plate 1111 has a first loading avoidance opening 1111b and a second loading avoidance opening 1111c, and the second cover plate 1121 has a third loading avoidance opening 1121b and a fourth loading avoidance opening 1121c. When the concrete specimen 200 is clamped between the first clamp plate 121 and the second clamp plate 122, and the two ends of the water injection cavity 200a are sealed and connected to the first cover plate assembly 111 and the second cover plate assembly 112 respectively, the first loading avoidance opening 1111b and the third loading avoidance opening 1121b avoid the first clamp plate 121, and the second loading avoidance opening 1111c and the fourth loading avoidance opening 1121c avoid the second clamp plate 122.

[0075] Since the two pull rods of this embodiment are arranged in parallel and spaced apart in the vertical direction, by setting the first loading avoidance port 1111b and the second loading avoidance port 1111c on the first cover plate 1111, and setting the third loading avoidance port 1121b and the fourth loading avoidance port 1121c on the second cover plate 1121, the first clamping plate 121 and the second clamping plate 122 can be prevented from contacting the first cover plate 1111 and the second cover plate 1121 and affecting the test results during the process in which the first clamping plate 121 and the second clamping plate 122 apply radial pressure P to the concrete specimen 200.

[0076] Another embodiment of the present application also provides a concrete water permeability resistance test method, which is implemented using the concrete water permeability resistance test device 100 provided in the above embodiment. Fig.11 , the method mainly comprises the following steps:

[0077] S301: Divide a plurality of cylindrical concrete specimens with water injection cavities into three groups, the three groups of concrete specimens being a first group of specimens, a second group of specimens and a third group of specimens, the concrete specimens in the first group of specimens being concrete specimen one, the concrete specimens in the second group of specimens being concrete specimen two, and the concrete specimens in the third group of specimens being concrete specimen three;

[0078] Specifically, the geometric dimensions of the concrete specimens 200 of this embodiment are all 75 mm in inner diameter, 150 mm in outer diameter, and 150 mm in height. Before the test, the concrete specimens 200 can be manufactured and cured according to the mix ratio of the tunnel concrete material under study and in accordance with the provisions of Chapter 3 of the Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete (GB / T50082-2009). The test method of this embodiment prepares a total of six concrete specimens 200, two concrete specimens 200 in each group, and the test methods used for the concrete specimens 200 in the same group of specimens are exactly the same. For the convenience of description, in this embodiment, the concrete specimens 200 in the first group of specimens are collectively referred to as concrete specimen one. However, in order to facilitate the distinction between the two concrete specimens one in the first group of specimens, one of the concrete specimens one can be marked as No. 1 and the other concrete specimen one can be marked as No. 2. Similarly, the concrete specimens 200 in the second group of specimens are collectively referred to as concrete specimen two, one of the two concrete specimens two is marked as No. 3 and the other is marked as No. 3. The concrete specimens 200 in the third group of specimens are collectively referred to as concrete specimen three, one of the two concrete specimens three is marked as No. 5 and the other is marked as No. 6.

[0079] It is understandable that the number of concrete specimens 200 is not limited to six. In other embodiments, the number of concrete specimens 200 can be adjusted as needed, but it is necessary to ensure that there is at least one concrete specimen 200 in each of the first group of specimens, the second group of specimens and the third group of specimens.

[0080] S302: The first cover plate assembly and the second cover plate assembly are respectively sealed and connected to the two ends of the water injection cavity of the concrete specimen 1; water reaching a preset water pressure is loaded into the water injection cavity of the concrete specimen 1 by an automatic pressurizing machine until the water seeps out from the outer wall of the concrete specimen 1; according to the loading data recorded by the automatic pressurizing machine during the water pressure loading process, the variation law of the concrete permeability coefficient under stress-free action is obtained; wherein the loading data includes the loading water amount corresponding to different time points during the water pressure loading process of the automatic pressurizing machine;

[0081] Specifically, in this embodiment, the concrete specimen one is subjected to water pressure loading, but no external load is applied. Therefore, the variation law of the concrete permeability coefficient obtained using the concrete specimen one is the variation law of the concrete permeability coefficient under no stress.

[0082] See also Figure 4 In this embodiment, when installing the concrete specimen 1, first place one end of the concrete specimen 1 into the second positioning groove 1121a of the second cover plate 1121, and ensure that the second sealing ring 1122 extends into the water injection cavity 200a and is in sealing contact with the side wall of the water injection cavity 200a. Then, add water into the water injection cavity 200a of the concrete specimen 1 to remove air. When the water surface is flush with the end face of the other end of the concrete specimen 1, cover the end face of the other end of the concrete specimen 1 with the first cover plate, and ensure that the first sealing ring 1112 extends into the water injection cavity 200a and is in sealing contact with the side wall of the water injection cavity 200a. Then, the first cover plate 1111 and the second cover plate 1121 are fastened and connected by bolts 113.

[0083] It should be noted that, since the concrete specimen one is subjected to water pressure loading but not external load loading, the concrete specimen one does not need to be clamped between the first clamping plate 121 and the second clamping plate 122 .

[0084] After the first cover plate assembly 111 and the second cover plate assembly 112 are sealed and connected to the two ends of the water injection cavity 200a of the concrete specimen 1, the automatic pressurizer is connected to the water injection channel 111a on the first cover plate 1111, and the automatic pressurizer is turned on to gradually increase the water pressure to the preset water pressure. The automatic pressurizer of this embodiment can load and stabilize the water pressure in the range of 0-15MPa. The specific preset water pressure required corresponds to the water pressure in the water environment where the concrete lining of the studied tunnel is located. Optionally, the preset water pressure can be set to 0.4Mpa, 0.8Mpa and 1.2Mpa, and then the concrete specimen 1 is hydraulically loaded until the outer wall of the water concrete specimen 1 seeps out. During the entire hydraulic loading process, the automatic pressurizer can automatically record the amount of water loaded every once in a while, for example, every 30 minutes, so that the amount of water loaded corresponding to different time points can be obtained, and the amount of water loaded is equivalent to the amount of water seepage of the concrete specimen 1. Therefore, according to the amount of water loaded corresponding to different time points, the variation law of the concrete permeability coefficient under stress-free action can be obtained. It should be noted that the specific calculation method of the concrete permeability coefficient is common knowledge in the art and will not be repeated here.

[0085] In addition, the total duration of water pressure loading of the automatic pressurizing machine can also be determined as needed.

[0086] S303: clamping the second concrete specimen between the first clamping plate and the second clamping plate, and using the pushing mechanism to push the second clamping plate until the second concrete specimen is subjected to compression and bending failure; in the process of the pushing mechanism pushing the second clamping plate, recording the magnitude of the pushing force loaded by the pushing mechanism and the displacement of the second clamping plate under the action of different magnitudes of the pushing force, and obtaining the variation law of the elastic modulus without water pressure according to the obtained pushing force loaded by the pushing mechanism and the corresponding displacement of the second clamping plate, and determining the peak value of the pushing force loaded by the pushing mechanism;

[0087] Specifically, in this embodiment, mainly based on the finite element method, a beam-spring model or a shell-spring model is used to calculate the bending moment and axial force of the concrete lining vault of the tunnel under study, and the compressive stress of the vault is calculated according to the eccentric compression theory of concrete. Subsequently, a finite element model or an elastic mechanics model of the concrete specimen 200 is established to calculate the variation law of the vault compressive stress under different radial pressures P. Finally, the radial pressure P to be applied in the test, that is, the jacking force loaded by the jacking mechanism 124, is obtained through the compressive stress equivalence.

[0088] In this embodiment, only external load is applied to the concrete specimen 2, but no water pressure is applied. Therefore, the variation law of the elastic modulus of the concrete specimen 2 without water pressure is obtained by using the concrete specimen 2.

[0089] It should be noted that, since the concrete specimen 2 is only subjected to external load but not water pressure loading, the concrete specimen 2 does not need to be sealed and connected to the first cover plate assembly 111 and the second cover plate assembly 112 .

[0090] In this embodiment, the thrust force applied by the thrust mechanism 124 to the second clamping plate 122 is gradually increased, and the thrust mechanism 124 can set the thrust force to the size required for the test. Each time the thrust mechanism 124 loads the thrust force, the magnitude of the thrust force loaded is recorded, as well as the corresponding displacement of the second clamping plate 122, which is measured by a displacement sensor. According to the thrust force loaded by the thrust mechanism 124 and the corresponding displacement of the second clamping plate 122, a pressure-displacement curve can be drawn, and then the change law of the elastic modulus under the action of no water pressure and the peak value of the thrust force loaded by the thrust mechanism 124 can be obtained.

[0091] In addition, as required, the length and width of the cracks generated in the concrete specimen 2 under the action of jacking forces of different magnitudes can also be recorded to obtain the crack variation law of the concrete specimen 2.

[0092] It should be noted that there is no order of precedence between step S302 and step S303, and the two steps can be interchanged.

[0093] S304: sealingly connecting the two ends of the water injection cavity of the concrete specimen three to the first cover plate assembly and the second cover plate assembly respectively, and clamping the sealed concrete specimen three between the first clamping plate and the second clamping plate; within a preset time, using an automatic pressurizing machine to load water reaching a preset water pressure into the water injection cavity of the concrete specimen three, and using a pushing mechanism to push the second clamping plate, wherein the maximum value of the pushing force loaded by the pushing mechanism is less than the peak value of the pushing force loaded by the pushing mechanism obtained in the test on the concrete specimen two; according to the loading data recorded by the automatic pressurizing machine during the water pressure loading process, obtaining the variation law of the concrete permeability coefficient under the action of the external load; wherein the loading data includes the amount of water loaded by the automatic pressurizing machine at different time points during the water pressure loading process;

[0094] Specifically, since the concrete specimen 3 is subjected to water pressure loading and external load loading at the same time, the variation law of the concrete permeability coefficient obtained using the concrete specimen 3 is the variation law of the concrete permeability coefficient under the external load.

[0095] For concrete specimen three, the entire test time is determined as needed. For example, the preset time can be 12 hours. During the test of concrete specimen three, the thrust applied by the jacking mechanism 124 to the second clamping plate 122 is gradually increased. However, the maximum value of the thrust loaded by the jacking mechanism 124 is smaller than the peak value of the thrust loaded by the jacking mechanism 124 obtained in the test on concrete specimen two. That is to say, concrete specimen three does not need to be destroyed under the action of external load.

[0096] In this step, the loading data recorded by the automatic pressurizing machine during the water pressure loading process is obtained in the same manner as in step S302, and the variation law of the concrete permeability coefficient under the external load is obtained based on the obtained loading data.

[0097] In addition, as required, the same method as in step S303 may be used to obtain the variation law of the elastic modulus under the action of water pressure.

[0098] S305: Compare the variation law of the concrete permeability coefficient under the external load obtained with the variation law of the concrete permeability coefficient under no stress to determine the influence of the concrete mechanical damage under the external load on the concrete permeability.

[0099] Furthermore, as required, after the above test is completed, the concrete specimen three may be split radially to observe the difference in permeability of different parts of the concrete specimen three.

[0100] Since the structure and load form of the concrete test piece 200 of this embodiment are similar to those of the concrete lining of a tunnel, the test results can be used to evaluate the permeability of the concrete lining of a tunnel in a high water pressure environment.

[0101] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A concrete water permeability test device, used for testing the water permeability of a cylindrical concrete specimen, wherein the concrete specimen has a water injection cavity that penetrates the concrete specimen axially, and is characterized in that: include: A hydraulic loading device, the hydraulic loading device comprising an automatic pressurizing machine, and a first cover plate assembly and a second cover plate assembly respectively connected to both ends of the concrete specimen in a sealed manner, the first cover plate assembly having a water injection channel for connecting the automatic pressurizing machine and the water injection cavity; An external load loading device, the external load loading device includes a first clamping plate, a second clamping plate, a guide member, a pushing mechanism, a mounting plate and a displacement sensor; the first clamping plate is fixedly connected to the guide member, the second clamping plate is slidably connected to the guide member, the first clamping plate and the second clamping plate are used to clamp the concrete specimen from both radial sides of the concrete specimen; the mounting plate is fixedly connected to the guide member and is located on the side of the second clamping plate away from the first clamping plate, the pushing mechanism is installed on the mounting plate, and the telescopic pushing part of the pushing mechanism faces the second clamping plate; the displacement sensor is connected to the first clamping plate and the second clamping plate, and is used to detect the displacement of the second clamping plate during the process of the pushing mechanism pushing the second clamping plate.

2. The concrete water permeability resistance testing device according to claim 1, characterized in that: The first cover plate assembly comprises a first cover plate having the water injection channel, and a first sealing ring arranged on one side of the first cover plate, wherein the first sealing ring is located around the water outlet of the water injection channel; the first sealing ring is used to seal and contact with the end surface of one end of the concrete specimen; The second cover plate assembly includes a second cover plate and a second sealing ring arranged on one side of the second cover plate; the second sealing ring is used for sealing contact with the end surface of the other end of the concrete specimen.

3. The concrete water permeability resistance testing device according to claim 2, characterized in that: One side of the first cover plate has a first positioning groove for matching with one end of the concrete specimen, the water injection channel is communicated with the first positioning groove, and the first sealing ring is arranged in the first positioning groove; One side of the second cover plate has a second positioning groove for matching with the other end of the concrete specimen, and the second sealing ring is arranged in the second positioning groove.

4. The concrete water permeability resistance testing device according to claim 1, characterized in that: The first cover plate assembly includes a first cover plate, the water inlet of the water injection channel is arranged on the side wall of the first cover plate, and the water outlet of the water injection channel is arranged on an end surface of one side of the first cover plate.

5. The concrete water permeability resistance testing device according to claim 4, characterized in that: The water injection channel includes a threaded connection section and an extension section connected to one end of the threaded connection section. The opening of the threaded connection section away from the end of the extension section is the water inlet, and the opening of the extension section away from the end of the threaded connection section is the water outlet.

6. The concrete water permeability resistance testing device according to claim 1, characterized in that: The first cover plate assembly is firmly connected to the second cover plate assembly.

7. The concrete water permeability resistance testing device according to claim 1, characterized in that: Part of the structure of the second clamping plate protrudes outward to form an abutment boss; When the concrete specimen is clamped between the first clamping plate and the second clamping plate, the abutting boss abuts against the concrete specimen.

8. The concrete water permeability resistance testing device according to claim 7, characterized in that: The guide member is a pull rod, and the first clamping plate and the second clamping plate are both inserted into the pull rod.

9. The concrete water permeability resistance testing device according to claim 8, characterized in that: There are two pull rods, which are arranged in parallel and spaced apart, and a specimen accommodating space is formed between the two pull rods; One of the two pull rods is inserted through one end of the first clamping plate and the second clamping plate, and the other of the two pull rods is inserted through the other end of the first clamping plate and the second clamping plate.

10. The concrete water permeability resistance testing device according to claim 9, characterized in that: The two pull rods are arranged in parallel and spaced apart in the vertical direction, the first cover plate assembly comprises a first cover plate, the first cover plate has a first loading avoidance opening and a second loading avoidance opening, and the second cover plate has a third loading avoidance opening and a fourth loading avoidance opening; When the concrete specimen is clamped between the first clamping plate and the second clamping plate, and the two ends of the water injection cavity are respectively sealed and connected to the first cover plate assembly and the second cover plate assembly, the first loading avoidance port and the third loading avoidance port avoid the first clamping plate, and the second loading avoidance port and the fourth loading avoidance port avoid the second clamping plate.

11. A method for testing concrete water permeability resistance, implemented by using the concrete water permeability resistance testing device according to any one of claims 1 to 10, characterized in that: The method comprises the following steps: Divide a plurality of cylindrical concrete specimens with water injection cavities into three groups, the three groups of concrete specimens are respectively a first group of specimens, a second group of specimens and a third group of specimens, the concrete specimens in the first group of specimens are concrete specimens one, the concrete specimens in the second group of specimens are concrete specimens two, and the concrete specimens in the third group of specimens are concrete specimens three; The first cover plate assembly and the second cover plate assembly are respectively sealed and connected to the two ends of the water injection cavity of the concrete specimen one; the water reaching a preset water pressure is loaded into the water injection cavity of the concrete specimen one by the automatic pressurizing machine until the water seeps out from the outer wall of the concrete specimen one; according to the loading data recorded by the automatic pressurizing machine during the water pressure loading process, the variation law of the concrete permeability coefficient under stress-free action is obtained; wherein the loading data includes the loading water amount corresponding to different time points of the automatic pressurizing machine during the water pressure loading process; The second concrete specimen is clamped between the first clamping plate and the second clamping plate, and the second clamping plate is pushed by the pushing mechanism until the second concrete specimen is subjected to compression and bending failure; in the process of the pushing mechanism pushing the second clamping plate, the magnitude of the pushing force loaded by the pushing mechanism and the displacement of the second clamping plate under the action of different magnitudes of pushing forces are recorded, and the variation law of the elastic modulus under the action of no water pressure is obtained according to the obtained pushing force loaded by the pushing mechanism and the corresponding displacement of the second clamping plate, and the peak value of the pushing force loaded by the pushing mechanism is determined; The two ends of the water injection cavity of the concrete specimen three are sealed and connected to the first cover plate assembly and the second cover plate assembly respectively, and the sealed concrete specimen three is clamped between the first clamping plate and the second clamping plate; within a preset time, the water reaching a preset water pressure is loaded into the water injection cavity of the concrete specimen three by using the automatic pressurizing machine, and the second clamping plate is pushed by the pushing mechanism, wherein the maximum value of the pushing force loaded by the pushing mechanism is less than the peak value of the pushing force loaded by the pushing mechanism obtained in the test on the concrete specimen two; according to the loading data recorded by the automatic pressurizing machine during the water pressure loading process, the variation law of the concrete permeability coefficient under the action of the external load is obtained; wherein the loading data includes the amount of water loaded by the automatic pressurizing machine at different time points during the water pressure loading process; The obtained variation law of the concrete permeability coefficient under the external load is compared with the variation law of the concrete permeability coefficient under the stress-free condition to determine the influence of concrete mechanical damage under the external load on concrete permeability.

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