In-situ test apparatus and test method for simulating the stress failure characteristics of gravity dams

Abstract

This invention discloses an in-situ testing device and method for simulating the stress-induced failure characteristics of gravity dams, belonging to the field of hydraulic engineering testing technology. The technical solution adopted in this invention includes an in-situ testing device comprising a mold for casting concrete to create gravity dam specimens and a crack preparation device for creating cracks in the gravity dam specimens, as well as a multi-stage stress loading device and a hydraulic loading device. This invention, employing a multi-stage stress loading device and a loading method with multiple loading points, solves the technical problem that traditional methods cannot achieve stress testing on gravity dams with cracks having azimuth angles, and addresses the previous limitation that a single loading point could not simulate the stress experienced when a crack exists above that loading point, thus achieving the simulation of the stress-induced failure characteristics of real gravity dams.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic engineering testing technology, specifically relating to an in-situ testing device and method for simulating the stress failure characteristics of gravity dams. Background Technology

[0002] With the development of my country's water conservancy and hydropower industry, a large number of water conservancy projects have been built, making significant contributions to hydropower generation, ecological construction, flood control, and drainage. Among these, concrete gravity dams, as a commonly used dam type, are widely used in water conservancy projects, such as the Three Gorges Dam and the Xin'anjiang Dam. However, concrete gravity dams are known for their tendency to crack, as factors such as temperature and humidity can cause varying degrees of surface cracking during the concrete pouring process. These cracks can become potential channels for water seepage from upstream reservoirs, posing a significant potential threat to the safety and stability of the concrete gravity dams.

[0003] Experimental research is an important means to obtain the stress failure characteristics of gravity dams and study their failure mechanism. For the simulation of upstream reservoir water pressure, equivalent load is often applied. However, existing research has the following shortcomings: (1) Traditional gravity dam tests adopt the operation of first pouring, then positioning, anchoring, and loading. First, the positioning is easy to be inaccurate, resulting in the difference between the stress characteristics of gravity dam and the actual situation; second, the later anchoring requires destructive anchoring of gravity dam specimens, which leads to stress concentration at the anchoring point during the loading process, and cracks extend from there, thus affecting the actual test results; third, the anchoring point and gravity dam specimen are not a whole, resulting in uneven stress; (2) Existing large gravity dam specimens are different from small-scale regular specimens, and it is difficult to prefabricate cracks using the traditional pre-embedded steel plate method, especially cracks with different orientations and angles. These cracks with different orientation characteristics are This is also a real situation in actual gravity dams. The literature "Experimental Study on Damage Characteristics of Non-through Cracked Concrete" also mentions that concrete strength, deformation failure and internal damage are closely related to the crack inclination angle; (3) Most existing gravity dam specimens adopt a single-point loading mode (i.e., the loading position is located at 1 / 3 of the normal water level). In the stress test of gravity dam specimens in the laboratory, for example, the literature "Comparative Analysis of Deformation Model Tests of Gravity Dam and Gravel Dam" does not consider the crack characteristics of gravity dams. If the crack characteristics of gravity dams are to be considered, when the crack is located above the equivalent load, the equivalent load has no effect on the stress of the crack. However, the actual water pressure is continuously distributed on the upstream surface of the gravity dam specimen. The crack is subjected to bending moment from the water pressure above it and water pressure within it. However, under the equivalent load, considering the crack's location above the equivalent load's stress point, the crack will not experience the corresponding bending moment from the water pressure due to the equivalent load. The literature "Deformation Analysis of Gravity Dam Hydraulic Splitting Failure Structure" considers the cracks and loads in a gravity dam and uses a high-stiffness distribution beam to apply force to the dam, enabling crack propagation tests. However, the load is not equivalent to the actual water level. Furthermore, due to the randomness of crack distribution in a gravity dam, the cracks are not necessarily horizontal and have a certain azimuth angle, while the applied force in this literature... The force method cannot be used to conduct stress tests on cracks with azimuth angles. Because the cracks have azimuth angles and span in the gravity direction of the gravity dam, existing distribution beams cannot be used to apply stress within the span of the cracks. Even if the size of the distribution beams can be adapted to the different characteristic parameters of the cracks, each crack with different characteristic parameters requires the fabrication of a suitable distribution beam, making the test process cumbersome and costly. In addition, applying internal water pressure to the cracks also presents technical difficulties. For example, the sealing of the water pressure inside the cracks is easily affected by the distribution beams. Since the distribution beams are custom-made, the opening positions of the distribution beams need to be consistent with the crack positions during the test, which presents alignment difficulties. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an in-situ test device for simulating the stress failure characteristics of a gravity dam; another purpose of this invention is to provide a test method for the in-situ test device for simulating the stress failure characteristics of a gravity dam.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an in-situ test device for simulating the stress failure characteristics of a gravity dam, comprising a mold for casting concrete to make a gravity dam specimen and a crack preparation device for creating cracks in the gravity dam specimen, further comprising a multi-stage stress loading device and a hydraulic loading device; the mold comprises a mold base plate, and ribs are installed on the inner wall of the mold base plate; the crack preparation device comprises a crack maker and a moving positioning component for moving and positioning the crack maker; the moving positioning component comprises a moving frame, a telescopic rod disposed inside the moving frame, two sliding hinges hinged to the two ends of the telescopic rod, and a moving frame groove provided on the inner wall of the moving frame for sliding of the sliding hinges; the crack maker is slidably mounted on the telescopic rod.

[0006] The test method using the above-mentioned in-situ test apparatus for simulating the stress and failure characteristics of a gravity dam includes the following steps:

[0007] (1) Pour concrete into the mold to make a gravity dam specimen;

[0008] (2) Determine the characteristic parameter values ​​of the crack, which are the location of the crack center point, the crack length, and the crack azimuth angle; use a crack fabrication device to fabricate cracks on the gravity dam specimen;

[0009] (3) Determine the number of stress loading points, the location of each loading point, and the load value of each loading point; use a multi-stage stress loading device to apply load values ​​to the gravity dam specimen at each loading point, and at the same time use a water pressure loading device to apply internal water pressure values ​​to the cracks.

[0010] (4) Use a high-speed camera to record the failure process of the gravity dam specimen until the end of the test.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] (1) The in-situ test device is equipped with ribs, which can realize the in-situ casting of gravity dam specimens, solve the positioning problem of traditional gravity dam specimens, and avoid the use of anchor bolts, which would damage the integrity of gravity dam specimens. The anchoring device of the present invention is an integral part of the gravity dam specimen, and the force is uniform, which can reflect the true stress state of the gravity dam specimen.

[0013] (2) By moving and positioning the crack maker arbitrarily, the crack maker can be made to correspond to each position of the stress surface of the gravity dam specimen, and cracks with arbitrary characteristic parameters that conform to the actual working conditions can be made.

[0014] (3) By adopting a multi-stage stress loading device and a loading method with multiple loading points, the technical problem that traditional methods cannot realize the stress test of gravity dams with cracks with azimuth angles is solved. This solves the problem that a single loading point cannot simulate the stress of cracks existing above the loading point, and realizes the simulation of the stress failure characteristics of real gravity dams. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the mold base plate and the rib platform;

[0016] Figure 2 This is a schematic diagram of the mold structure;

[0017] Figure 3 Axonometric view of the structure of the fracture fabrication device;

[0018] Figure 4 A schematic front view of the structure of the fracture fabrication device;

[0019] Figure 5 Axonometric view of the structure of a fracture fabricator;

[0020] Figure 6 A schematic front view of the structure of the fracture fabricator;

[0021] Figure 7 A rear view showing the structure of a fracture fabricator;

[0022] Figure 8 This is a schematic assembly drawing of the telescopic rod.

[0023] Figure 9 A schematic diagram of the telescopic rod and the slit fabricator;

[0024] Figure 10 A schematic diagram showing the positions of the crack fabrication device and the mold;

[0025] Figure 11 This is an isometric view of the structure of the crack sealing device;

[0026] Figure 12 This is an isometric view of the in-situ test loading device.

[0027] Figure 13 This is a schematic front view of the in-situ test loading device.

[0028] Figure 14 Locating the location and size of the crack on the upstream face of the gravity dam;

[0029] Figure 15 This is a schematic diagram of a level four load.

[0030] Figure 16 This is a schematic diagram of a three-level load.

[0031] Figure 17 This is a schematic diagram of the application of a secondary load.

[0032] Figure 18 This is a schematic diagram of the application of a Class I load.

[0033] Among them, 1 is the mold base plate, 2 is the rib platform, 3 is the groove of the mold base plate, 4 is the mold side plate, 5 is the pouring gate, 6 is the moving frame, 7 is the moving frame slide groove, 8 is the sliding hinge, 9 is the bottom fixing platform, 10 is the bottom fixing platform bolt, 11 is the strong magnet, 12 is the telescopic rod, 12-1 is the slide rod, 12-2 is the slide rod groove, 13 is the narrow hole, 14 is the crack positioning groove, 15 is the anchor, 16 is the spacer rod, and 17 is the crack control... 18 is the positioning bolt for the fracture maker, 19 is the anchor bolt, 20 is the positioning bolt hole for the fracture maker, 21 is the boss of the sliding rod, 22 is the groove of the sliding rod, 23 is the gravity dam specimen, 24 is the sealing bolt, 25 is the sealing strip, 26 is the water outlet, 27 is the moving column, 28 is the moving frame, 29 is the hydraulic rod, 30 is the force transmitter, 31 is the water pressure loading device, 32 is the base plate of the moving column, and 33 is the water supply pipe. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] The in-situ test apparatus for simulating the stress failure characteristics of a real gravity dam according to the present invention includes a mold for casting concrete to make a gravity dam specimen and a crack preparation device for making cracks in the gravity dam specimen, and also includes a multi-stage stress loading device and a hydraulic loading device.

[0036] like Figure 1 and Figure 2As shown, the mold used for casting concrete to make a gravity dam specimen includes a mold base plate 1 and mold side plates 4 that form an inner cavity with the mold base plate 1. The shape of the inner cavity is the same as the shape of the gravity dam specimen. Ribs 2 are installed on the mold base plate 1. The mold base plate 1 has a mold base plate groove 3. The mold side plates 4 are installed in the mold base plate groove 3. The upper end of the mold has a pouring port 5, which is used to pour concrete into the inner cavity to form the gravity dam specimen 23. Multiple ribs 2 are arranged in an array. The ribs 2 are made of high-strength steel and consist of an upper large-diameter cylinder and a lower small-diameter cylinder. The ribs are made of high-strength steel to ensure that the gravity dam specimen does not break under stress. The lower small-diameter cylinder and the upper large-diameter cylinder provide strong anchoring for the gravity dam specimen, preventing it from detaching from the mold base plate under stress. The cast-in-place anchoring feature ensures that the ribs 2 and the gravity dam specimen 23 are a single unit, bearing stress as a whole without significant stress concentration. To facilitate demolding, lubricating oil is applied to the inner wall of the mold side plate 4, and then the mold side plate 4 is installed in the groove 3 of the base plate. Concrete is poured into the cavity through the pouring port 5. After 28 days, the mold side plate 4 is removed, thus forming the in-situ cast-in-place gravity dam specimen 23 with good stress characteristics.

[0037] like Figures 3-4 As shown, the fracture fabrication device includes a fracture fabricator 17 and a moving positioning assembly for moving and positioning the fracture fabricator 17. The moving positioning assembly includes a moving frame 6, a telescopic rod 12 disposed inside the moving frame 6, two sliding hinges 8 hinged to both ends of the telescopic rod 12, and a moving frame groove 7 provided on the inner wall of the moving frame 6 for sliding the sliding hinges 8. The fracture fabricator 17 is slidably mounted on the telescopic rod 12. The moving frame groove 7 includes a straight groove provided on the inner wall of the side of the moving frame 6 and an arc-shaped groove provided on the inner wall of the corner of the moving frame 6. The moving frame 6 is fixed to the bottom fixing platform 9 by bottom fixing platform bolts 10.

[0038] like Figure 5 and Figure 6 As shown, the telescopic rod 12 consists of a slide rod 12-1 and a slide rod groove 12-2. The slide rod 12-1 has a slide rod boss 21, and the slide rod groove 12-2 has a slide rod groove 22 corresponding to the slide rod boss 21. The slide rod 12-1 can move along the slide rod groove 12-2, and the length of the telescopic rod 12 can freely extend or retract. When the two sliding hinges 8 move on the inner wall of the moving frame, the telescopic rod 12 can freely extend and retract according to the change in distance between the two sliding hinges 8, thus adapting to various deformation requirements to achieve positioning of different crack orientations. Figure 3 As shown, the sliding hinge 8 is made of stainless steel and can be positioned by adsorption using a strong magnet 11. It is worth noting that the shape and size of the movable frame 6 can be changed to accommodate different crack locations.

[0039] like Figures 7-10 As shown, the fracture maker 17 has a fracture positioning groove 14 inside for inserting a motor drill bit to create fractures; the fracture maker is slidably mounted on the telescopic rod 12, and the telescopic rod 12 has a narrow hole 13 along its length. One end of the spacer 16 passing through the narrow hole 13 is fixedly connected to the fracture maker 17, and the other end is fixedly connected to the anchor 15 through the anchor bolt 19. The spacer 16 is located inside the narrow hole 13 and slides inside the narrow hole 13 so that the fracture maker 17 can slide on the telescopic rod 12. The fracture maker 17 is fixed to the telescopic rod 12 through the fracture maker positioning bolt 18 and the fracture maker positioning bolt hole 20 on the telescopic rod 12, realizing the real-time positioning operation of the fracture maker 17 to create fractures on the gravity dam specimen 23.

[0040] The water pressure loading device 31 applies water pressure to the surface test cracks of the gravity dam specimen; such as Figure 11 As shown, the crack sealing device includes a sealing bolt 24 and a sealing strip 25. The sealing strip 25 is fixed to the surface of the gravity dam specimen 23 by the sealing bolt 24 to seal the crack. The sealing strip 25 has a water passage hole 26, which allows the water pressure from the water pressure loading device 31 to flow from the water supply pipe 33 into the crack through the water passage hole 26.

[0041] like Figure 12 and Figure 13 As shown, the multi-stage stress loading device includes multiple sliding frames 28, hydraulic rods 29 connected to the sliding frames 28, and force transmitters connected to the hydraulic rods 29. A sliding column 27 is mounted on a sliding column base plate 32, and the sliding frames 28 are mounted on the sliding columns 27. The sliding frames 28 can be moved up and down along the sliding columns 27 via a hydraulic device. Preferably, four sliding frames 28 are used, allowing for position adjustment during testing to flexibly load different points on the upper part of the gravity dam specimen. The hydraulic rods 29 are mounted on the sliding frames 28 and can move horizontally towards the gravity dam specimen 23 along the horizontal direction of the sliding frames 28 to achieve the function of loading horizontal stress. The force transmitter 30 is mounted on the hydraulic rods 29 and can apply uniform stress to the upstream dam surface of the gravity dam specimen 23.

[0042] The test method using the above-mentioned in-situ test apparatus simulating the stress and failure characteristics of a real gravity dam includes the following steps:

[0043] (1) Pour concrete into the mold to make a gravity dam specimen;

[0044] (2) Determine the characteristic parameters of the crack, namely crack length, center point coordinates and crack azimuth angle; use a crack fabrication device to fabricate cracks on the gravity dam specimen;

[0045] (3) Determine the number of stress loading points, the location of each loading point, and the load value of each loading point; use a multi-stage stress loading device to apply load values ​​to the gravity dam specimen at each loading point, and at the same time use a water pressure loading device to apply internal water pressure values ​​to the test cracks.

[0046] (4) Use a high-speed camera to record the failure process of the gravity dam specimen until the end of the test.

[0047] In step (1), the size of the gravity dam specimen is based on the actual gravity dam. To facilitate demolding, lubricating oil is applied to the inner wall of the mold side plate 4, and then the mold side plate 4 is installed in the groove 3 of the bottom plate. Concrete is poured through the pouring port 5 to fill the inner cavity. After 28 days, the mold side plate 4 is removed, and a gravity dam specimen 23 with good stress characteristics can be formed by in-situ casting.

[0048] In step (2), the characteristic parameters of the test cracks are determined. Based on the actual field survey of the gravity dam, the distribution of cracks on the upstream dam face of the gravity dam is statistically analyzed. The characteristic parameters are the length of the crack, the coordinates of the center point, and the azimuth angle of the crack.

[0049] Step (2), the method for creating test cracks on gravity dam specimens using a crack-making device, includes the following steps:

[0050] (21) Adjust the bottom fixing platform 9 and the bottom fixing platform bolt 10 to position the crack making device in a suitable position according to the size of the gravity dam specimen 23.

[0051] (22) Adjust the position of the sliding hinge 8 so that the telescopic rod 12 and the position of the crack are parallel in the plane;

[0052] (23) Move the crack maker 17 so that the crack positioning groove 14 on the crack maker 17 completely coincides with the position of the crack.

[0053] (24) The electric drill bit is inserted into the crack positioning groove 14 and drills to the corresponding depth to complete the initial crack positioning;

[0054] (25) Remove the crack-making device and use a grinding pestle to grind the inside of the initial crack to complete the crack making.

[0055] In step (3), the multi-stage stress loading device is equipped with four sliding frames, capable of handling first-stage, second-stage, third-stage, and fourth-stage loads; for example... Figure 14As shown, the height h of the gravity dam specimen and the characteristic parameters of the crack are: the coordinates of the center point (xp, yp), the length lf of the crack (the crack length lf is extremely small compared to the dam size), and the azimuth angle β of the crack; the coordinates of point A (xp+1 / 2lf·cosβ, yp+1 / 2lf·sinβ) and point B (xp-1 / 2lf·cosβ, yp-1 / 2lf·sinβ) of the two ends of the crack; the range of β is 0°~180°, because 180°~360° is a symmetrical case; considering the water pressure... The increased length of the loading device is considered in this invention. Specifically, the coordinates of point A on the outermost edge of the hydraulic loading device are (xp + 1 / 2lf·cosβ + he·cosβ, yp + 1 / 2lf·sinβ + he·sinβ), and the coordinates of point B are (xp - 1 / 2lf·cosβ - he·cosβ, yp - 1 / 2lf·sinβ - he·sinβ), where he is the increased length of the hydraulic loading device. When the ordinate of the corrected point A is less than the equivalent load position of the first-level load, i.e. When determining the first-level load, the number of loading points for the first-level load is 1, and the location of the first-level loading point is... The load value is Where ρ is the density of water, and g is the acceleration due to gravity; when At that time, determine the secondary load, tertiary load, and quaternary load.

[0056] The number of loading points for the secondary load is 2. The method for determining the secondary load is as follows: At that time, and When using a two-stage load, starting from top to bottom, the location of the first-stage loading point is determined as l1, and its value range is... Right now The load value is The location of the second-level loading point is determined as follows: The load value is in

[0057] The number of loading points for the third-level load is 3. The method for determining the third-level load is as follows: At that time, and When using a three-level load, starting from top to bottom, the location of the first-level loading point is determined as l1, and its value range is... Right now The load value is The location of the second-stage loading point is determined to be l2, and its value range is... Right now The load value is in The location of the third-level loading point is determined as follows The load value is in

[0058] The number of loading points for the fourth-level load is 4. The method for determining the fourth-level load is when yp + 1 / 2lf·sinβ + he·sinβ < h, and At that time, a four-level load was adopted. From top to bottom, the position of the first-level loading point was determined as l1, and its value range was yp+1 / 2lf·sinβ+he·sinβ<h-l1<h, i.e., 0<l1<h-(yp+1 / 2lf·sinβ+he·sinβ). The load value was... The location of the second-stage loading point is determined to be l2, and its value range is... Right now The load value is in The location of the third-level loading point is determined to be l3, and its value range is... The load value is in The location of the fourth-level loading point is determined as follows The load value is in

[0059] (I) For the loading method of level four load, i.e., four stress loading points, such as Figure 15 As shown.

[0060] Determine the position l1 of the first-stage loading point from top to bottom. The position of the first-stage loading point is the equivalent stress location of the triangular load. Since the load at the first-stage loading point is a triangular load, the length of its vertical side is... The load value of the equivalent water pressure is Therefore, the key to adjustment is to first determine the location l1 of the first-level stress loading point, and then determine its equivalent water pressure load value:

[0061] The load at the second-level loading point from top to bottom is a trapezoidal load. First, determine the position l2 of the second-level loading point. Then, the equivalent load of the trapezoidal load is located at the length of its vertical side: The formula for the equivalent load of a trapezoid is: Among them, h t Let be the right-angled side of the right trapezoid, 'a' be the upper base, and 'b' be the lower base. According to the equivalent load formula for a trapezoid, the vertical length h1 of the trapezoidal load is calculated as follows:

[0062]

[0063] The equivalent water pressure load value at the second-stage loading point is: Therefore, the key to adjustment is to first determine the location l2 of the second-level stress loading point, and then determine the equivalent water pressure load value:

[0064] The load at the third loading point from top to bottom is a trapezoidal load. First, determine the position l3 of the third loading point. Then, the equivalent load of the trapezoidal load is located at the length of its vertical side: According to the equivalent load formula for a trapezoid, the vertical length h2 of the trapezoidal load is calculated as follows:

[0065]

[0066] The equivalent water pressure load value at the third loading point is: Therefore, the key to adjustment is to first determine the location l3 of the third-level loading point, and then determine the equivalent water pressure load value:

[0067] The load at the fourth loading point from top to bottom is a trapezoidal load, and the vertical side h3 of the trapezoidal load is completely determined. Based on the equivalent load formula for a trapezoid, the location of the fourth-level stress loading point can be calculated. At the same time, its equivalent water pressure load value can be determined as follows: Therefore, the key to adjustment is to first calculate and determine the location of the fourth-level stress loading point: Then, the equivalent water pressure load value is determined as follows:

[0068] (II) For the three-level load method, i.e., three stress loading points, such as Figure 16 As shown.

[0069] Determining the position l1 of the first-stage loading point from top to bottom, the location of the stress loading point is the equivalent stress location of the triangular load. Since the load at the first-stage loading point is a triangular load, the length of its vertical side is... The equivalent water pressure load value is Therefore, the key to adjustment is to first roughly determine the location l1 of the first-level stress loading point, and then determine its equivalent water pressure load value:

[0070] Determining the second level as a trapezoidal load from top to bottom, first determine the location l2 of the second level stress loading point. Then, the equivalent load of the trapezoidal load is located at the length of its vertical side: According to the equivalent load formula for a trapezoid, the vertical length h1 of the trapezoidal load is:

[0071]

[0072] The equivalent water pressure load value at the second-stage loading point is: Therefore, the key to adjustment is to first determine the location l2 of the second-level stress loading point, and then determine its equivalent water pressure load value:

[0073] The load at the third loading point, determined from top to bottom, is a trapezoidal load. The vertical side h2 of this trapezoidal load is now fully determined. Based on the equivalent load formula for a trapezoid, the location of the third-level stress loading point can be calculated. At the same time, its equivalent water pressure load value can be determined as follows: Therefore, the key to adjustment is to first calculate and determine the location of the third-level stress loading point: Then, its equivalent water pressure load value is determined as follows:

[0074] (III) For the loading method of secondary load, i.e., two stress loading points, such as Figure 17 As shown.

[0075] From top to bottom, the position of the first-stage loading point, l1, is the equivalent stress location of the triangular load. Since the load at the first-stage loading point is a triangular load, the length of its vertical side is... The equivalent water pressure load value is Therefore, the key to adjustment is to first determine the location l1 of the first-level stress loading point, and then determine its equivalent water pressure load value:

[0076] From top to bottom, the load at the second-level loading point is a trapezoidal load, and the vertical side h1 of the trapezoidal load is completely determined. The location of the second-level stress loading point can be calculated. At the same time, its equivalent water pressure load value can be determined as follows:

[0077] (IV) For the loading method of Level 1 load, i.e., one stress loading point, such as... Figure 18 As shown.

[0078] The location of the first-level stress loading point is determined as follows: The equivalent water pressure load value is:

[0079] Depending on the experimental requirements and the location of the precast cracks, the load levels, i.e., the number of loading points, can be flexibly selected. Therefore, it can effectively adapt to different crack locations to simulate the stress conditions of cracks in real concrete gravity dams. After determining the load levels and equivalent water pressure load values, based on the location of the crack, the height h at its center is calculated. c Based on, hc =h-yp The water pressure applied inside is defined as: ρgh c .

[0080] Example 1

[0081] The actual gravity dam has a height of 181m. After being scaled down proportionally, the dimensions of the gravity dam specimen in this embodiment are h = 150cm and xl = 200cm. The characteristic parameters of the crack are: the location of the crack center point is (xp, yp) = (60, 30), the crack length lf = 10cm, and the crack azimuth angle β = 30°. The added length he of the hydraulic loading device is taken as 5cm.

[0082] yp + 1 / 2lf·sinβ + he·sinβ = 30 + 1 / 2 × 10 × sin30° + 5 × sin30° = 35cm < 1 / 3h = 50cm. Therefore, according to our newly added judgment condition 1), we determine the first-level load at this time. The number of loading points for the first-level load is 1, and the location of the loading point is... The load value is The water pressure inside the fracture is determined to be ρgh. c =1000×10×(1.5-0.3)=12000Pa.

[0083] Example 2

[0084] The actual gravity dam has a height of 181m. After being scaled down proportionally, the dimensions of the gravity dam specimen in this embodiment are h = 150cm and xl = 200cm. The characteristic parameters of the crack are: the location of the crack center point is (xp, yp) = (60, 120), the crack length lf = 10cm, and the crack azimuth angle β = 30°. The added length he of the hydraulic loading device is taken as 5cm.

[0085] Since 1 / 3h = 50cm < yp + 1 / 2lf·sinβ + he·sinβ = 120 + 1 / 2 × 10 × sin30° + 5 × sin30° = 125cm < h = 150cm, and yp - 1 / 2lf·sinβ - he·sinβ = 120 - 1 / 2 × 10 × sin30° - 5 × sin30° = 115cm > 3 / 4 × h = 112.5cm, a level four load is determined, and the number of loading points for the level four load is 4.

[0086] The position of the first loading point from top to bottom is l1. The range of l1 is 0 < l1 < h - (yp + 1 / 2lf·sinβ + he·sinβ), that is, 0 < l1 < 25cm. We take l1 = 20cm, and the load value is...

[0087] The second loading point from top to bottom is located at l2, and the value range of l2 is... That is, 15cm < l2 < 55cm, so we take l2 = 30cm. The load value is

[0088] The third loading point from the top is located at l3, and the value range of l3 is... That is, 37.5cm < l3 < 75cm, so we take l3 = 50cm.

[0089] The load value is

[0090]

[0091] The position of the fourth level loading point from top to bottom is:

[0092] The load value is

[0093] The water pressure inside the fracture is determined to be ρgh. c =1000×10×(1.5-1.2)=3000Pa.

[0094] Example 3

[0095] The actual gravity dam has a height of 181m. After being scaled down proportionally, the dimensions of the gravity dam specimen in this embodiment are h = 150cm and xl = 200cm. The characteristic parameters of the crack are: the location of the crack center point is (xp, yp) = (60, 50), the crack length lf = 10cm, and the crack azimuth angle β = 30°. The added length he of the hydraulic loading device is taken as 5cm.

[0096] Since 1 / 3h = 50cm < yp + 1 / 2lf·sinβ + he·sinβ = 50 + 1 / 2 × 10 × sin30° + 5 × sin30° = 55cm < And yp-1 / 2lf·sinβ-he·sinβ=50-1 / 2×10×sin30°-5×sin30=45cm> The secondary load is determined, and the number of loading points for the secondary load is 2.

[0097] The position of the first loading point from top to bottom is l1, and the range of values ​​for l1 is... That is, 75cm < l1 < 95cm, so we take l1 = 80cm; the load value is

[0098] The location of the second-level loading point from top to bottom is...

[0099] The water pressure inside the fracture is determined to be ρgh. c =1000×10×(1.5-0.5)=10000Pa.

Claims

1. A test method for an in-situ test device based on simulated gravity dam stress failure characteristics, characterized in that, The experimental apparatus includes a mold for casting concrete to create gravity dam specimens and a fracture preparation device for creating fractures in the gravity dam specimens. It also includes a multi-stage stress loading device and a hydraulic loading device. The mold includes a mold base plate with ribs mounted on its inner wall. The fracture preparation device includes a fracture maker and a movable positioning assembly for moving and positioning the fracture maker. The movable positioning assembly includes a movable frame, a telescopic rod inside the movable frame, two sliding hinges hinged to the ends of the telescopic rod, and a movable frame groove on the inner wall of the movable frame for sliding the sliding hinges. The fracture maker is slidably mounted on the telescopic rod. The method includes the following steps: (1) Pour concrete into the mold to make a gravity dam specimen; (2) Determine the characteristic parameter values ​​of the crack, which are the location of the crack center point, the crack length, and the crack azimuth angle; use a crack fabrication device to fabricate cracks on the gravity dam specimen; (3) Determine the number of stress loading points, the location of each loading point, and the load value of each loading point; use a multi-stage stress loading device to apply load values ​​to the gravity dam specimen at each loading point, and at the same time use a water pressure loading device to apply internal water pressure values ​​to the cracks. (4) The failure process of the gravity dam specimen was recorded using a high-speed camera until the end of the test; In step (3), the height h of the gravity dam specimen, the characteristic parameters of the crack are the center point coordinates (xp, yp), the crack length lf, the crack azimuth angle β, the coordinates of point A (xp+1 / 2lf·cosβ, yp+1 / 2lf·sinβ) and point B (xp-1 / 2lf·cosβ, yp-1 / 2lf·sinβ) of the two ends of the crack, and the range of β is 0°~180°. Considering the increased length of the hydraulic loading device, the modified A of the outermost part of the hydraulic loading device. The coordinates of point A are (xp+1 / 2lf·cosβ+he·cosβ, yp+1 / 2lf·sinβ+he·sinβ), while the corrected coordinates of point B are (xp-1 / 2lf·cosβ-he·cosβ, yp-1 / 2lf·sinβ-he·sinβ), where he is the length of the added hydraulic loading device; when the corrected ordinate of point A is less than the equivalent load position of the first-level load, i.e., yp+1 / 2lf·sinβ+he·sinβ < When the first-order load is determined, the number of loading points for the first-order load is 1; when yp+1 / 2lf·sinβ+he·sinβ> At that time, determine whether it is a level 2 load, level 3 load, or level 4 load.

2. The test method according to claim 1, characterized in that, The number of loading points for the secondary load is 2, and the method for determining the secondary load is as follows: when yp + 1 / 2lf·sinβ + he·sinβ < At that time, and yp-1 / 2lf·sinβ-he·sinβ> When the load is applied, a secondary load is used; the number of loading points for the tertiary load is 3, and the method for determining the tertiary load is as follows: when yp + 1 / 2lf·sinβ + he·sinβ < At that time, and yp-1 / 2lf·sinβ-he·sinβ> When the load is applied, a three-level load is used; the number of loading points for the four-level load is 4, and the method for determining the four-level load is as follows: when yp + 1 / 2lf·sinβ + he·sinβ < At that time, and yp-1 / 2lf·sinβ-he·sinβ> At that time, a level four load was applied.

3. The test method according to claim 1, characterized in that, The multiple ribs are arranged in an array; each rib consists of an upper large-diameter cylinder and a lower small-diameter cylinder.

4. The test method according to claim 1, characterized in that, The fracture maker has a fracture positioning groove inside for inserting a motor drill bit to create fractures.

5. The test method according to claim 1, characterized in that, The sliding groove of the moving frame includes a straight sliding groove provided on the inner wall of the side of the moving frame and an arc-shaped sliding groove provided on the inner wall of the corner of the moving frame.

6. The test method according to claim 1, characterized in that, The telescopic rod includes a sliding rod and a sliding rod groove. During the movement of the sliding hinge, the sliding rod can move along the sliding rod groove to extend or retract the length of the telescopic rod.

7. The test method according to claim 1, characterized in that, The multi-stage stress loading device includes multiple sliding frames, each of which is connected to a hydraulic rod, and the hydraulic rod is connected to a force transmitter.

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