Testing device for axial force loss and anchoring force deterioration of pre-stressed anchor cable under dry-wet cycle

Abstract

The utility model provides a pre-stressed anchor cable axial force loss and anchoring force deterioration test device under dry-wet cycle, which comprises a test water tank for accommodating a standard rock mass test block; the water injection and drainage device is arranged on the test water tank and used for controlling water level change in the water tank; the anchoring structure is composed of an anchor cable implanted into a preset hole channel of the rock mass test block and a grouting body poured between the preset hole channel and the anchor cable; the strain gauges are arranged at intervals in the axial direction of the anchoring section of the anchor cable; the pressure gauge is sleeved on the anchor cable; the plurality of hygrometers are buried in the grouting body; the strain gauges, the hygrometer and the pressure meter are connected with the data acquisition instrument through cables; and the heating assembly is arranged in the rock mass test block and the test water tank and is used for simulating a temperature change environment. According to the invention, the simulation of the dry-wet cycle working environment of the rock mass test block is realized, the drying process of the rock mass test block is accelerated through the heating assembly, the test time consumption is shortened, meanwhile, the hygrometer is matched to accurately control the dry-wet index of the test sample, and the accurate and controllable test variable is realized.

Description

Technical Field

[0001] This utility model relates to the field of engineering support technology, specifically to a test device for axial force loss and anchorage force deterioration of prestressed anchor cables under wet-dry cycles. Background Technology

[0002] Due to its advantages such as strong adaptability, short construction period, and high economy, anchor cable support has been widely used in geotechnical engineering fields such as slope protection and underground caverns. Prestressed anchor cables, by applying pre-tension, can effectively improve the stress distribution of the soil and rock mass, reduce deformation, and enhance overall stability.

[0003] The construction of hydropower dams alters the original hydrogeological environment of the reservoir bank area. For example, during the operation of the power station, reservoir slopes and other engineering projects will be affected by the periodic rise and fall of the reservoir water level. This periodic water level fluctuation will cause the reservoir bank rock mass to be in a long-term wet-dry cycle environment. For reservoir slope engineering projects using anchor cable support, the long-term wet-dry cycle can easily cause the anchoring performance of the anchor cables to deteriorate, affecting the support effect. The safety and durability of the anchor cable support system are the foundation for ensuring the safe and stable operation of the project and are crucial to the safe operation of the project.

[0004] Wet-dry cycles refer to the repeated drying and wetting processes that occur in natural environments. These environmental conditions can alter the internal structure of the soil and rock, reducing their strength and consequently weakening the anchoring force of the anchor cables. Under wet-dry cycles, the interface between the grouting material and the soil and rock in the anchoring section is prone to physicochemical changes, such as decreased interfacial bonding and crack propagation. This leads to a gradual degradation of anchoring performance, a gradual loss of prestress, and ultimately affects the long-term stability of the support structure.

[0005] Currently, the degradation characteristics of prestressed anchor cable anchoring force under long-term wet-dry cycle conditions are mainly calculated using load distribution theory based on the degradation characteristics of the mechanical properties of the rock mass or grouting body. However, engineering practice and experimental verification are lacking. Therefore, inventing a simple, economical, and effective testing device to obtain the prestress loss and anchoring force degradation characteristics of prestressed anchor cables under long-term wet-dry cycle conditions would provide an important means for evaluating the long-term stability of reservoir slopes. Utility Model Content

[0006] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a test device for the axial force loss and anchorage force deterioration of prestressed anchor cables under dry and wet cycles.

[0007] This utility model provides a test apparatus for the axial force loss and anchorage force deterioration of prestressed anchor cables under wet and dry cycles, including:

[0008] The test water tank is used to hold standard rock mass test blocks;

[0009] A water inlet / outlet device is installed on the test water tank to control the water level changes in the tank.

[0010] The anchoring structure consists of anchor cables implanted in pre-set ducts in rock mass test blocks and grout injected between the pre-set ducts and anchor cables.

[0011] Multiple strain gauges are arranged at intervals along the axial direction of the anchoring section of the anchor cable;

[0012] A pressure gauge is fitted onto the anchor cable;

[0013] Multiple humidity meters are embedded in the grouting body;

[0014] The strain gauge, hygrometer, and pressure gauge are connected to the data acquisition instrument via cables.

[0015] Heating components are installed inside the rock mass specimen and the test water tank to simulate temperature change environments.

[0016] In one embodiment, the upper part of the rock mass test block is provided with a lower pressure plate, a hydraulic jack and an upper pressure plate in sequence. The hydraulic jack is placed between the lower pressure plate and the upper pressure plate and is pressurized by a servo loading control system. The anchor cable passes through the lower pressure plate and the upper pressure plate in sequence.

[0017] In one embodiment, the bottom of the test water tank is provided with permeable stones.

[0018] In one embodiment, the heating assembly includes a heating rod and a heating plate, the heating rod being inserted into the rock mass specimen and the heating plate being disposed inside the test water tank and around the rock mass specimen.

[0019] In one embodiment, the water inlet and outlet device includes an inlet valve and an outlet valve. The inlet valve is located at the top of the test water tank, and the outlet valve is located at the bottom of the test water tank. Both the inlet valve and the outlet valve are connected to an external water pipe.

[0020] In one embodiment, a locking device is provided on the anchor cable above the pressure gauge.

[0021] In one embodiment, the side of the anchor cable is provided with a slot, and a plurality of strain gauges are arranged in the slot, with the strain gauges spaced apart along the axial direction of the anchoring section of the anchor cable.

[0022] The beneficial effects of the test device for prestressed anchor cable axial force loss and anchorage force deterioration under dry and wet cycles provided in this embodiment of the invention are as follows:

[0023] This invention simulates the wet-dry cycle working environment of rock mass test blocks through a water injection and drainage device, accelerates the drying process of rock mass test blocks through a heating component, shortens the test time, and is equipped with a hygrometer to accurately control the wet-dry index of the test samples, so as to achieve precise control of test variables.

[0024] The experimental apparatus of this invention is simple in structure, easy to operate, and economical. Using this apparatus, axial force loss tests and anchorage force degradation tests can be conducted, thereby quantitatively revealing the relationship between axial force loss, ultimate anchorage force, and the bond strength between the rock mass and grouting body interface and the number of wet-dry cycles in prestressed anchor cables. This provides a basis for the design of engineering anchor cable support and the evaluation of long-term stability. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the experimental device structure provided in an embodiment of the present invention;

[0027] Figure 2 A three-dimensional structural schematic diagram of the experimental apparatus provided in the embodiments of the present invention;

[0028] Figure 3 A top view of the test apparatus provided in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the anchor cable provided in an embodiment of the present invention.

[0030] Figure reference numerals: 1-Test water tank; 11-Inlet valve; 12-Drain valve; 2-Rock block; 21-Permeable stone; 22-Preset channel; 23-Heating hole; 3-Hydraulic jack; 31-Lower pressure plate; 32-Upper pressure plate; 33-Servo loading control system; 4-Anchor cable; 41-Slotted; 42-Strain gauge; 43-Grouting body; 51-Heating rod; 52-Heating plate; 53-Temperature controller; 6-Data acquisition instrument; 61-Hygrometer; 62-Pressure gauge; 71-Locking device; 72-Tensioning device. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of this utility model, the preferred embodiments of this utility model are described below in conjunction with specific examples. However, it should be understood that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the present utility model. For better illustration of this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable that some well-known structures and their descriptions may be omitted in the drawings for those skilled in the art. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present utility model.

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0033] like Figures 1 to 4 As shown, the test device for axial force loss and anchorage force deterioration of prestressed anchor cables under wet-dry cycles includes: a test water tank 1, which is welded from steel plates and has an open top to accommodate standard rock mass specimens 2; a water injection and drainage device, installed on the test water tank 1, for controlling the water level changes in the test water tank 1; an anchorage structure, consisting of anchor cables 4 implanted in preset channels 22 of the rock mass specimen 2 and grout 43 injected between the preset channels 22 and the anchor cables 4; multiple strain gauges 42, arranged at intervals along the axial direction of the anchorage section of the anchor cables 4; a pressure gauge 62, sleeved on the anchor cables 4; multiple hygrometers 61, embedded in the grout 43, for detecting wet-dry indices during the wet-dry cycle; the strain gauges 42, hygrometers 61, and pressure gauges 62 are connected to a data acquisition instrument 6 via cables; and a heating component, installed inside the rock mass specimen 2 and the test water tank 1, for simulating temperature change environments.

[0034] The upper part of the rock mass test block 2 is sequentially equipped with a lower pressure plate 31, a hydraulic jack 3, and an upper pressure plate 32. At least two hydraulic jacks 3 are provided, symmetrically arranged on both sides of the anchor cable 4. The hydraulic jacks 3 are placed between the lower pressure plate 31 and the upper pressure plate 32, and the pressure is controlled by a servo loading control system 33, which drives the upper pressure plate 32 to move upward, applying a pull-out force to the anchor cable 4. The lower pressure plate 31 and the upper pressure plate 32 have circular holes in their centers, and the anchor cable 4 passes through the lower pressure plate 31 and the upper pressure plate 32 in sequence. The side of the anchor cable 4 is provided with a slot 41, in which multiple strain gauges 42 are arranged. The multiple strain gauges 42 are arranged at intervals along the axial direction of the anchoring section of the anchor cable 4 within the slot 41.

[0035] A locking device 71 is installed on the anchor cable 4 above the pressure gauge 62, and the initial prestress is applied to the anchor cable by the tensioning device 72. The prestress is locked at the design tension load by the locking device 71.

[0036] The bottom of the test water tank 1 is equipped with a permeable stone 21, which can accelerate the drainage of water from the bottom of the test block.

[0037] The heating assembly includes a heating rod 51 and a heating plate 52. The heating rod 51 is inserted into the heating hole 23 of the rock mass specimen 2, and the heating plate 52 is placed inside the test water tank 1 and around the rock mass specimen 2. When simulating the drying process, the heating rod 51 is placed in the heating hole 23, and the heating plate 52 is placed on the four sides of the test block 2. The power supply is connected, and the heating temperature is controlled by the temperature controller 53 to quickly dry the rock mass specimen 2.

[0038] The water inlet and outlet device includes an inlet valve 11 and an outlet valve 12. The inlet valve 11 is located at the upper part of the test water tank 1, and the outlet valve 12 is located at the lower part of the test water tank 1. Both the inlet valve 11 and the outlet valve 12 are connected to an external water pipe.

[0039] The wet and dry treatment steps are as follows: Close the drain valve 12 at the bottom of the test water tank 1, and inject water into the test water tank 1 through the inlet valve 11 to ensure that the rock mass specimen 2 is completely submerged in water. The rock mass specimen 2 is then immersed in water to saturate it. The saturation level of the specimen is monitored in real time by the hygrometer 61 until the value no longer increases, at which point it can be considered completely saturated. Then, the drain valve 12 is opened to drain the water from the test water tank 1. The heating rod 51 is inserted into the heating hole 23, and the heating plate 52 is placed around the specimen. The rock mass specimen 2 is heated by the temperature controller to promote its rapid drying. The moisture content is monitored by the hygrometer 61 until it no longer changes, at which point the rock mass specimen 2 can be considered completely dry.

[0040] Based on the description and drawings of this utility model, those skilled in the art can easily manufacture or use the test device for axial force loss and anchorage force deterioration of prestressed anchor cables under wet and dry cycles, and can produce the positive effects described in this utility model.

[0041] Unless otherwise specified, in this utility model, terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe orientation or positional relationships in this utility model are for illustrative purposes only and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood in conjunction with the accompanying drawings and according to the specific circumstances.

[0042] Unless otherwise expressly specified and limited, the terms "set up," "connected," and "linked" in this utility model should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A device for testing the loss of axial force and the deterioration of anchoring force of a prestressed anchor cable under wet-dry cycles, characterized in that: include: The test water tank is used to hold standard rock mass test blocks; A water inlet / outlet device is installed on the test water tank to control the water level changes in the tank. The anchoring structure consists of anchor cables implanted in pre-set ducts in rock mass test blocks and grout injected between the pre-set ducts and anchor cables. Multiple strain gauges are arranged at intervals along the axial direction of the anchoring section of the anchor cable; A pressure gauge is fitted onto the anchor cable; Multiple humidity meters are embedded in the grouting body; The strain gauge, hygrometer, and pressure gauge are connected to the data acquisition instrument via cables. Heating components are installed inside the rock mass specimen and the test water tank to simulate temperature change environments. 2.The device for testing the loss of the axial force and the deterioration of the anchoring force of the prestressed anchor cable under the dry-wet cycle according to claim 1, characterized in that: The upper part of the rock mass test block is provided with a lower pressure plate, a hydraulic jack and an upper pressure plate in sequence. The hydraulic jack is placed between the lower pressure plate and the upper pressure plate and is pressurized by a servo loading control system. The anchor cable passes through the lower pressure plate and the upper pressure plate in sequence. 3.The device for testing the loss of the axial force and the deterioration of the anchoring force of the prestressed anchor cable under the dry-wet cycle according to claim 1, characterized in that: The bottom of the test water tank is equipped with permeable stones. 4.The device for testing the loss of the axial force and the deterioration of the anchoring force of the prestressed cable under the dry-wet cycle according to claim 1, characterized in that: The heating assembly includes a heating rod and a heating plate. The heating rod is inserted into the rock mass specimen, and the heating plate is placed inside the test water tank and around the rock mass specimen. 5.The device for testing the loss of the axial force of the prestressed cable and the deterioration of the anchoring force under the dry-wet cycle according to claim 1, characterized in that: The water inlet and outlet device includes an inlet valve and an outlet valve. The inlet valve is located at the top of the test water tank, and the outlet valve is located at the bottom of the test water tank. Both the inlet valve and the outlet valve are connected to an external water pipe. 6.The device for testing the loss of the axial force and the deterioration of the anchoring force of the prestressed cable under the dry-wet cycle according to claim 1, characterized in that: A locking device is installed on the anchor cable above the pressure gauge. 7.The device for testing the loss of the axial force and the deterioration of the anchoring force of the prestressed cable under the dry-wet cycle according to claim 1, characterized in that: The anchor cable has a slot on its side, and multiple strain gauges are arranged in the slot. The multiple strain gauges are arranged at intervals along the axial direction of the anchoring section of the anchor cable.

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