Osmotic pressure monitoring structure and construction method thereof

Abstract

The invention provides an osmotic pressure monitoring structure and a construction method thereof.The osmotic pressure monitoring structure comprises a drill hole, the drill hole extends downwards from the upper surface of a toe board, penetrates through the toe board and extends into a rock mass below the foundation plane of the toe board, and the drill hole is integrally formed in the downstream side of an anti-seepage curtain; an osmometer is arranged at the bottom of the drill hole, a filling material is poured upwards from the bottom surface of the drill hole, a preset distance is formed between the top surface of the filling material and the toe board basic surface, the osmometer is arranged in the filling material, and a plugging body is arranged above the filling material; the plugging body comprises three sections of plugging structures which are sequentially arranged from bottom to top, specifically, a first in-hole plugging structure which is arranged on a drilling section in a rock body below a toe board foundation plane and upwards spans the toe board foundation plane to extend into the drilling section in a toe board; the second in-hole plugging structure is arranged on the drilling section in the toe board; and the external pressing and plugging structure is pressed and covered outside the drilling hole opening. The osmotic pressure monitoring device is installed on the toe board on the upstream of the dam body, drilling does not need to penetrate through special cushion materials, and potential quality hazards are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy and hydropower engineering building monitoring facilities, and particularly relates to a seepage pressure monitoring structure and a construction method thereof. BACKGROUND

[0002] Seepage pressure monitoring is an important means to master the seepage state of dam body and dam foundation during dam operation and to ensure the safe operation of the project. Conventional seepage pressure monitoring instruments are usually arranged on the downstream side of the anti-seepage structure, i.e. under the dam body and dam foundation downstream of the toe slab, so as to obtain seepage information of the key parts.

[0003] The construction process of the existing seepage pressure monitoring device is usually as follows: after the construction of the toe slab is completed, rockfill is filled downstream of the toe slab, and panel pouring and curtain grouting operations are simultaneously carried out on the rockfill. After the curtain grouting is completed, drilling for seepage pressure gauge installation needs to be carried out under the dam body and dam foundation, and the drilling needs to be plugged. The drilling needs to penetrate through the special cushion material, and after the installation is completed, the special cushion material needs to be repaired, but this process easily disturbs the cushion structure and causes quality problems. In addition, in some projects, grouting is carried out simultaneously with panel pouring, and if the seepage pressure gauge installation is not arranged properly, process conflicts are easily caused, which affects the construction and monitoring effect of the structure. SUMMARY

[0004] In view of the deficiencies in the prior art, a first object of the present application is to provide a seepage pressure monitoring structure. The present application installs the seepage pressure monitoring device on the toe slab upstream of the dam body, and the drilling does not need to penetrate through the special cushion material, thereby reducing the quality problems.

[0005] In the first aspect, the present application provides a seepage pressure monitoring structure, comprising a drilling hole, the drilling hole extends downward from the upper surface of the toe slab, penetrates through the toe slab and extends into the rock mass below the base surface of the toe slab, and the drilling hole is arranged on the downstream side of the anti-seepage curtain; a seepage pressure gauge is arranged at the bottom of the drilling hole, and a filling material is filled upward from the bottom surface of the drilling hole, the top surface of the filling material has a predetermined distance from the base surface of the toe slab, the seepage pressure gauge is arranged in the filling material, and a plugging body is arranged above the filling material;

[0006] The plugging body comprises three sections of plugging structures arranged in sequence from bottom to top, specifically:

[0007] A first in-hole plugging structure, arranged in the drilling hole segment in the rock mass below the base surface of the toe slab and extending upward to the drilling hole segment inside the toe slab;

[0008] A second in-hole plugging structure, arranged in the drilling hole segment inside the toe slab;

[0009] An external pressure plugging structure, pressure-plugged outside the drilling hole.

[0010] In an embodiment, the first in-hole sealing structure comprises a first pre-shrunk mortar layer and a first SR plastic filler layer arranged from bottom to top, the first pre-shrunk mortar layer is filled to a position below the toe base surface and close to the toe base surface, and the first SR plastic filler layer extends from the borehole section in the rock mass to the borehole section inside the toe, forming a closed layer across the toe base surface.

[0011] In an embodiment, the second in-hole sealing structure comprises a second pre-shrunk mortar layer and a second SR plastic filler layer arranged from bottom to top.

[0012] In an embodiment, the thickness of the second SR plastic filler layer is 3cm-5cm.

[0013] In an embodiment, the external overburden sealing structure is a cast-in-situ concrete overburden block overburdened on the borehole opening.

[0014] In an embodiment, the data line of the osmometer passes through the first in-hole sealing structure, the second in-hole sealing structure, and the external overburden sealing structure, and is arranged in a multi-layer annular structure inside the external overburden sealing structure.

[0015] In an embodiment, the borehole is arranged away from the anti-seepage curtain, and the arrangement type of the borehole comprises an arrangement in a downward downstream direction or a vertical arrangement.

[0016] In an embodiment, a protection pipe is arranged in the borehole section of the rock mass, and the osmometer, part of the filling material, and part of the structure of the first in-hole sealing structure are arranged inside the protection pipe.

[0017] In an embodiment, the filling material comprises a first fine sand layer, a gravel layer, a second fine sand layer, and a clay layer arranged in sequence from the bottom of the borehole upwards, and the osmometer is arranged in the first fine sand layer.

[0018] In a second aspect, a second object of the present application is to provide a construction method of the osmotic pressure monitoring structure according to any one of the above-mentioned embodiments, the construction method comprising the following steps:

[0019] S1, positioning the borehole position on the toe surface according to the design requirements, and drilling to the designed depth in the predetermined direction;

[0020] S2, placing the osmometer at the bottom of the borehole, and sequentially filling fine sand, gravel, fine sand, and clay to complete the arrangement of the filling material around and above the osmometer;

[0021] When the geological conditions are poor and the borehole has a risk of hole collapse, a protection pipe is arranged in the borehole section below the toe base surface after the borehole is completed;

[0022] S3, mixing the quick-setting and slightly-expanding mortar, and filling the borehole to close to the toe base surface on the top of the filling material;

[0023] S4, after the initial setting of the first pre-shrinkage mortar layer, continue to fill SR plastic filler on the upper part thereof, and use an end flat tool to layer and compact, the filling height of the SR plastic filler exceeds the toe plate base surface;

[0024] S5, mix micro-expansion mortar, continue to fill the toe plate section hole, and approach the hole;

[0025] S6, chisel the surface of the toe plate in the area where the cast-in-place concrete weight block is arranged, and arrange a plurality of inserted reinforcement;

[0026] S7, lay a layer of SR plastic filler on the surface of the hole, and compact and seal;

[0027] S8, after the formwork is set in the area where the cast-in-place concrete weight block is arranged, pour and compact the concrete;

[0028] S9, the data line of the osmotic pressure meter is introduced after the osmotic path is appropriately extended in the structure inside the cast-in-place concrete weight block.

[0029] The osmotic pressure monitoring structure and the construction method thereof provided by the application have the following beneficial effects:

[0030] The osmotic pressure monitoring device is installed on the toe plate upstream of the dam body, the drilling does not need to penetrate through special cushion material, and the quality hidden danger is reduced. By arranging the segmented plugging structure below and above the toe plate base surface, including the pre-shrinkage mortar layer and the SR plastic filler layer, and arranging the cast-in-place concrete weight block at the drilling hole, the sealing stability and the overall anti-seepage performance of the osmotic pressure monitoring hole are significantly improved, the risk of external water seepage along the hole is reduced, and the service life of the structure is prolonged.

[0031] Further, the osmotic pressure meter installation process of the application is after the panel pouring and curtain grouting operation, which does not cause process conflict, affects the structure construction and monitoring effect, and the construction organization is more flexible.

[0032] The application sets a protection pipe in the rock mass section drilling hole, effectively deals with complex geological conditions such as hole collapse, and improves the stability of the drilling structure. By arranging the drilling hole on the downstream side of the anti-seepage curtain, and selecting inclined or vertical drilling arrangement form according to the width of the toe plate, the drilling hole is away from the center line of the curtain, avoids interference or structural damage to the anti-seepage curtain caused by drilling deviation or vibration during construction, reduces the construction interference risk from the source, and enhances the overall safety of the dam. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to make the technical solutions in the embodiments of the present application clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and other accompanying drawings can be obtained by those skilled in the art without any creative effort on the basis of these accompanying drawings.

[0034] Figure 1 A typical structure diagram of the seepage pressure monitoring structure without a protective pipe provided in the embodiments of the present application is shown in the figure.

[0035] Figure 2 A typical structure diagram of the seepage pressure monitoring structure with a protective pipe provided in the embodiments of the present application is shown in the figure.

[0036] Figure 3 A typical structure diagram of the prior art is shown in the figure.

[0037] Reference signs: 1, toe slab; 2, anti-seepage curtain; 3, drilling hole; 4, seepage pressure gauge; 5, first fine sand layer; 6, gravel layer; 7, clay layer; 8, first pre-shrunk mortar layer; 9, first SR plastic filler layer; 10, second pre-shrunk mortar layer; 11, cast-in-place concrete weight block; 12, embedded bar; 13, data line; 14, peripheral joint water stop; 15, protective pipe; 16, second SR plastic filler layer; 17, second fine sand layer; 18, face plate; 19, special bedding material; 20, toe slab foundation surface. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the technical solutions of the present application, the preferred embodiments of the present application will be described in combination with specific embodiments, but it should be understood that the accompanying drawings are only used for illustrative description and cannot be understood as a limitation on the present application; in order to better illustrate the embodiments, some components in the accompanying drawings will be omitted, enlarged or reduced, and do not represent the actual product size; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings can be omitted. The positional relationship described in the accompanying drawings is only used for illustrative description and cannot be understood as a limitation on the present application.

[0039] The present application will be further described in combination with the accompanying drawings and embodiments, but it is not used as a basis for limiting the present application.

[0040] As Figure 3 shown in the figure, in the prior art, the installation drilling hole 3 of the seepage pressure gauge 4 is arranged below the dam body and dam foundation, so it needs to penetrate the face plate 18 and the special bedding material 19, and this process is easy to disturb the bedding structure, causing quality hidden troubles.

[0041] Therefore, in view of the above problems, the present application provides a seepage pressure monitoring structure, as Figures 1 to 2As shown, it comprises a borehole 3 extending downward from the upper surface of the toe slab 1, penetrating the toe slab 1 and extending into the rock mass below the foundation surface of the toe slab, the borehole 3 being arranged on the downstream side of the impervious curtain 2; a piezometer 4 is arranged at the bottom of the borehole 3, the piezometer 4 being 10 cm away from the bottom of the borehole, and a filling material is poured upward from the bottom surface of the borehole 3, the top surface of the filling material being a predetermined distance from the foundation surface of the toe slab 20, and the piezometer 4 being arranged in the filling material, and a blocking body being arranged above the filling material.

[0042] In the present embodiment, the predetermined distance is not less than 20 cm, ensuring that there is a blocking section in the borehole 3 in the rock mass, which can improve the blocking effect and observation effect, otherwise the contact surface of the toe slab and the foundation may be affected by leakage and the borehole, causing problems such as grouting, which affects the monitoring effect.

[0043] The blocking body comprises three blocking structures arranged in sequence from bottom to top, specifically:

[0044] A first in-hole blocking structure arranged in the borehole section in the rock mass below the foundation surface 20 of the toe slab and extending upward to the borehole section inside the toe slab 1 across the foundation surface 20 of the toe slab;

[0045] A second in-hole blocking structure arranged in the borehole section inside the toe slab 1;

[0046] An external pressure covering blocking structure covering the outside of the borehole opening for enhancing the stability of the closure of the borehole opening.

[0047] The first in-hole blocking structure comprises a first pre-shrunk mortar layer 8 and a first SR plastic filler layer 9 arranged in sequence from bottom to top, the first pre-shrunk mortar layer 8 being filled to a position close to the foundation surface 20 of the toe slab below the foundation surface 20 of the toe slab, and the first SR plastic filler layer 9 extending from the borehole section in the rock mass to the borehole section inside the toe slab 1, forming a closed layer across the foundation surface 20 of the toe slab, the thickness of the first SR plastic filler layer 9 being 5 cm ~ 10 cm, and the required thickness of the first SR plastic filler layer 9 arranged in the borehole section in the rock mass being 3 ~ 5 cm.

[0048] The second in-hole blocking structure comprises a second pre-shrunk mortar layer 10 and a second SR plastic filler layer 16 arranged in sequence from bottom to top.

[0049] The thickness of the second SR plastic filler layer 16 is 3 cm ~ 5 cm.

[0050] The external pressure covering blocking structure is a cast-in-situ concrete weight block 11 covering the borehole opening, and a dowel bar 12 is arranged around the borehole 3, avoiding the peripheral joint pre-embedded water stop 14. The concrete strength and impervious grade of the cast-in-situ concrete weight block 11 are the same as those of the toe slab 1.

[0051] The data line 13 of the osmometer 4 passes through the first hole inner sealing structure, the second hole inner sealing structure and the outer pressure covering sealing structure, wherein the outer pressure covering sealing structure is arranged in a multi-layer annular structure inside the outer pressure covering sealing structure to prolong the seepage path of the external water around the osmometer 4 through the data line 13.

[0052] The drill hole 3 is arranged away from the anti-seepage curtain 2 to reduce the risk of interference or damage to the anti-seepage structure during the construction of the drill hole 3; the arrangement mode of the drill hole 3 includes an inclined arrangement in a downstream direction or a vertical arrangement.

[0053] Specifically, the drill hole 3 has a diameter of 100 mm, and the horizontal distance of the opening position from the center line of the anti-seepage curtain 2 is not less than 2 meters. In order to reduce the risk of interference of the drill hole 3 deflection on the curtain structure, the drill hole 3 is usually arranged in a downstream inclined manner to maximize the avoidance of the anti-seepage curtain 2 area. When the toe plate 1 is wide, causing the opening point to be more than 4 meters away from the center line of the anti-seepage curtain 2, a vertical drill hole 3 mode can be selected according to the actual engineering conditions.

[0054] A protection pipe 15 is arranged in the drill hole section of the rock mass, and the osmometer 4, part of the filling material and part of the structure of the first hole inner sealing structure are arranged inside the protection pipe 15. It is used to provide structural support and protection for the osmotic pressure monitoring system in the case of poor geological conditions or the risk of hole collapse.

[0055] In this embodiment, the protection pipe 15 is a steel pipe, which is placed in the drill hole 3 for protection when the drill hole 3 has poor geological conditions and hole collapse occurs. The protection range of the steel pipe is limited to the drill hole 3 in the rock mass, and the drill hole section in the range of the toe plate 1 shall not be provided with the steel pipe. The steel pipe has a diameter of 5 cm, the osmometer 4 is placed at the bottom, and the filling material and the hole sealing material are arranged between the steel pipe and the drill hole 3 and inside the steel pipe. The steel pipe is drilled with holes in the range of the first fine sand layer 5 and the gravel layer 6 at the bottom to form a flower pipe section.

[0056] The filling material includes the first fine sand layer 5, the gravel layer 6, the second fine sand layer 17 and the clay layer 7 arranged in the drill hole 3 from bottom to top in sequence, and the osmometer 4 is arranged in the first fine sand layer 5. The gravel size of the gravel layer 6 is 5mm~10mm.

[0057] The main purpose of the first fine sand layer 5 is to protect the osmometer 4, and it also has a certain water permeability to ensure that the osmometer 4 is in communication with the pore water of the drill hole 3. The depth of this section is generally 20 cm, and it wraps the entire osmometer 4.

[0058] The gravel layer 6 is a water permeable layer, which can prevent hole collapse during the operation of the drill hole 3. The hole depth of this section is generally 3m.

[0059] The second fine sand layer 17 and the clay layer 7 are a layer-by-layer transition, which are used as an isolation layer of the first pre-shrunk mortar layer 8.

[0060] The application further provides a construction method of the osmotic pressure monitoring structure.

[0061] S1, positioning the position of the drill hole 3 on the surface of the toe plate 1 according to the design requirements, and drilling in the predetermined direction to the designed depth;

[0062] S2, placing the osmotic pressure gauge 4 at the bottom of the drill hole 3, and sequentially filling fine sand, gravel, fine sand and clay to complete the arrangement of the filling material around and above the osmotic pressure gauge 4;

[0063] Wherein, the osmotic pressure gauge 4 should be soaked for not less than 2 hours before installation to keep saturated state, and the accumulated water in the hole should be pumped out before filling;

[0064] When the geological condition is poor and the drill hole 3 has the risk of hole collapse, the protection pipe 15 is arranged in the drill hole section below the toe plate base surface 20 after the completion of the drill hole 3;

[0065] S3, mixing the quick-setting micro-expansion mortar, and filling the drill hole 3 on the top of the filling material to approach the toe plate base surface 20;

[0066] S4, after the initial setting of the first pre-shrunk mortar layer 8, the SR plastic filler is continuously filled on the upper part thereof, and the layer is compacted by using the tool with flat end, and the filling height of the SR plastic filler exceeds the toe plate base surface 20;

[0067] S5, mixing the micro-expansion mortar, and continuously filling the drill hole 3 of the toe plate 1 section to approach the hole mouth;

[0068] S6, performing the chiseling treatment on the surface of the toe plate 1 in the area where the cast-in-situ concrete weight block 11 is arranged, and arranging 4 insertion bars 12;

[0069] S7, laying a layer of SR plastic filler on the surface of the hole mouth, and compacting and sealing;

[0070] S8, after the formwork is erected in the area where the cast-in-situ concrete weight block 11 is arranged, the concrete is poured and vibrated and compacted, and the reinforcement mesh is laid near the base surface to enhance the crack resistance and anti-seepage performance of the weight cover structure;

[0071] S9, the data line 13 of the osmotic pressure gauge 4 is led out after being appropriately extended in the osmotic path in the structure inside the cast-in-situ concrete weight block 11.

[0072] According to the description and drawings of the application, those skilled in the art can easily manufacture or use the osmotic pressure monitoring structure and the construction method thereof, and can produce the positive effects recorded in the application.

[0073] Unless otherwise defined, all terms used in disclosing aspects of the application, such as professional terms and technical terms, have the meanings as commonly understood by one of ordinary skill in the art to which this application belongs. By way of non-limiting example, the following definitions are provided.

[0074] Unless otherwise defined, all terms used in disclosing aspects of the application, such as professional terms and technical terms, have the meanings as commonly understood by one of ordinary skill in the art to which this application belongs. By way of non-limiting example, the following definitions are provided.

[0075] The above description is only the preferred embodiment of the application, not any form of limitation on the application, any simple modification and equivalent change of the above embodiment according to the technical essence of the application shall fall within the protection scope of the application.

Claims

1. A seepage pressure monitoring structure, characterized in that: The system includes a borehole extending downward from the upper surface of the toe plate, penetrating the toe plate and extending into the rock mass below its foundation surface. The borehole is arranged entirely on the downstream side of the seepage barrier. A piezometer is installed at the bottom of the borehole, and filling material is injected upward from the bottom of the borehole. The top surface of the filling material is at a predetermined distance from the foundation surface of the toe plate. The piezometer is located inside the filling material, and a sealing body is installed above the filling material. The sealing body comprises three sealing structures arranged sequentially from bottom to top, specifically: The first hole sealing structure is arranged in the borehole section of the rock mass below the toe plate foundation surface and extends upward across the toe plate foundation surface into the borehole section inside the toe plate. The second hole sealing structure is arranged in the drilling section inside the toe plate; An external pressure sealing structure is applied to the outside of the borehole opening.

2. The seepage pressure monitoring structure according to claim 1, characterized in that: The first borehole sealing structure includes a first pre-shrink mortar layer and a first SR plastic filler layer arranged from bottom to top. The first pre-shrink mortar layer fills to a position below and close to the toe plate foundation surface. The first SR plastic filler layer extends from the borehole section in the rock mass into the borehole section inside the toe plate, forming a sealing layer that spans the toe plate foundation surface.

3. The seepage pressure monitoring structure according to claim 1, characterized in that: The second hole sealing structure includes a second pre-shrink mortar layer and a second SR plastic filler layer arranged from bottom to top.

4. The seepage pressure monitoring structure according to claim 3, characterized in that: The thickness of the second SR plastic filler layer is 3cm to 5cm.

5. The seepage pressure monitoring structure according to claim 1, characterized in that: The external pressure sealing structure is a cast-in-place concrete weight block that is pressed onto the borehole opening.

6. The seepage pressure monitoring structure according to any one of claims 1 or 5, characterized in that: The data cable of the piezometer passes through the first hole sealing structure, the second hole sealing structure, and the external pressure sealing structure, wherein it is wrapped in a multi-layered ring structure inside the external pressure sealing structure.

7. The seepage pressure monitoring structure according to claim 1, characterized in that: The boreholes are arranged away from the seepage prevention curtain, and the arrangement of the boreholes includes either inclined downstream or vertical.

8. The seepage pressure monitoring structure according to claim 1, characterized in that: A protective pipe is installed inside the borehole section of the rock mass, and the piezometer, part of the filling material, and part of the sealing structure in the first borehole are installed inside the protective pipe.

9. The seepage pressure monitoring structure according to claim 1, characterized in that: The filling material includes a first fine sand layer, a gravel layer, a second fine sand layer, and a clay layer arranged sequentially from the bottom of the borehole upwards, and the piezometer is located in the first fine sand layer.

10. A construction method for a seepage pressure monitoring structure as described in any one of claims 1 to 9, characterized in that, The construction method includes the following steps: S1. Locate the drilling position on the surface of the toe plate according to the design requirements, and drill to the design depth in the predetermined direction; S2. Place the piezometer at the bottom of the borehole and fill it with fine sand, gravel, fine sand and clay in layers to complete the filling material arrangement around and above the piezometer. When geological conditions are poor and there is a risk of borehole collapse, a protective pipe should be installed in the borehole section below the toe slab foundation surface after the borehole is completed. S3. Mix quick-setting micro-expansion mortar and fill the drill holes on top of the filling material to near the toe slab foundation surface; S4. After the mortar of the first pre-shrink mortar layer has initially set, continue to fill the upper part with SR plastic filler and compact it in layers with a tool with flat ends. The filling height of SR plastic filler exceeds the foundation surface of the toe slab. S5. Mix the micro-expansion mortar and continue filling the drilled holes in the toe plate section until it is close to the hole opening; S6. Within the area where the cast-in-place concrete counterweight blocks are installed, the surface of the toe slab is roughened and multiple reinforcing bars are installed. S7. Lay a layer of SR plastic filler on the surface of the orifice and compact and seal it; S8. After setting up the formwork in the area where the cast-in-place concrete counterweight blocks are placed, pour concrete and vibrate it to compact it. S9. After appropriately extending the seepage path by wrapping the data cable of the piezometer inside the cast-in-place concrete counterweight structure, lead it out.

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