Composite drainage system within rock slopes

Abstract

This invention relates to a composite drainage system for rock slopes, belonging to the field of geotechnical engineering technology. It includes a deep drainage device (1), a siphon drainage device (3), and a slope toe water collection device (4). Based on the groundwater distribution characteristics of the rock slope, the deep drainage device (1) is installed in the middle and upper parts of the slope, and the siphon drainage device (3) is installed in the lower part. The deep drainage device (1) and the siphon drainage device (3) are optimized by opening rectangular permeable holes on the surface of the outer pipe and inserting an inner pipe wrapped with filter cloth inside the outer pipe. The groundwater discharged by the deep drainage device (1) and the siphon drainage device (3) flows into the slope toe water collection well (41) of the slope toe water collection device (4). This invention solves the problems of easy collapse of the borehole wall, easy blockage of the pipe, and poor durability in traditional deep drainage and siphon drainage systems, and optimizes the disadvantages of easy interruption of the siphon effect during siphon drainage.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering technology and relates to a composite drainage system for rock slopes that combines deep drainage and siphon drainage. Background Technology

[0002] The stability of high rock slopes is greatly influenced by groundwater, and timely drainage of groundwater from the slope is crucial to ensuring slope safety. Due to recharge from atmospheric precipitation and groundwater channels, groundwater in the middle and upper parts of rock slopes is often stored in localized areas such as rock strata and joint fissures, while a relatively stable water level or a larger water storage area exists only in the lower part of the slope. Currently, the traditional method for draining groundwater from within the slope is through the installation of deep drainage holes or siphon drainage pipes.

[0003] Traditional deep drainage holes often exhibit the following problems when used on high rock slopes:

[0004] 1. When the rock mass is relatively fractured, longer drainage holes are prone to collapse during construction, making it impossible to effectively install the drainage pipe to the intended position and affecting the drainage of deep groundwater on the slope. Therefore, it is necessary to use steel pipes for pipe-following drilling to ensure that the hole wall does not collapse. However, the cross-sectional design of deep drainage pipes generally requires drilling holes in the upper semicircle for water collection, while the lower semicircle is designed to be without holes for drainage. During the drilling process, the pipe rotates, and its rotation shape cannot be controlled, often resulting in the inability to finally install the perforated part of the hole wall in the upper semicircle, affecting the water collection and drainage effect.

[0005] Second, the geotextile wrapped around the outside of the pipe is prone to deformation or damage during installation, which fails to achieve the purpose of preventing pipe blockage. As a result, many drainage holes become clogged with mud and sand during use, affecting the drainage effect.

[0006] Third, slopes are easily deformed due to internal and external forces such as rock creep, unloading, and water pressure, which can cause local damage to the pipes in the rock strata and affect their durability.

[0007] Fourth, for drainage in the lower part of the slope, the use of inclined deep drainage holes often requires a very long length to reach the ideal drainage position, and the groundwater in the area below the drainage hole cannot be discharged.

[0008] However, traditional siphon drainage pipes often encounter the following problems when used on high rock slopes:

[0009] 1. Similar to deep drainage holes, there are problems such as hole collapse, deformation and damage of geotextile and permeable pipes, which affect durability and drainage effect;

[0010] Second, based on the characteristics of rock slopes, there is often no stable groundwater level in the middle and upper parts of the slope. Groundwater is generally stored in joints or fissures or local areas of the rock layer. The drainage effect of siphon pipes on local water storage zones is not as good as that of deep drainage pipes.

[0011] Third, due to seasonal factors, the middle and upper parts of the slope may experience water shortages outside the rainy season, thus interrupting the siphon effect. During the rainy season, artificial methods are needed to restore the siphon effect, which presents management difficulties and safety hazards.

[0012] IV. According to relevant research, the head of a siphon pipe is generally no more than 10m, which limits its application in drainage of deep water storage zones on rock slopes. Furthermore, when the head of the siphon pipe exceeds 9.3m, it is prone to blockage by sand particles in the water. Obvious air bubbles appear at a vertical height of 3.5m above the water surface, and strings of air bubbles appear at a vertical height of 5.4m. When the diameter of the siphon pipe is greater than 4mm, air bubble accumulation inside the pipe easily occurs, potentially interrupting the siphon effect. Conversely, siphon pipes that are too small have limited drainage capacity. Therefore, the use of siphon pipes in high rock slopes is constrained by many factors. Summary of the Invention

[0013] In view of this, the purpose of this invention is to provide a composite drainage system for rock slopes that combines deep drainage and siphon drainage to solve the problem of drainage within rock slopes.

[0014] To achieve the above objectives, the present invention provides the following technical solution:

[0015] A composite drainage system for rock slopes is installed on the slope surface, including a deep drainage device and a siphon drainage device. The siphon drainage device is located below the deep drainage device. A slope intercepting ditch is connected to one end of the deep drainage device near the slope surface. A slope toe water collection device is connected below the siphon drainage device. The drainage from the slope intercepting ditch is introduced into the slope toe water collection device.

[0016] Optionally, the deep drainage device includes an inclined drainage hole with a first outer pipe inside, a first inner pipe inside the first outer pipe, and a first filter cloth wrapped around the outside of the first inner pipe. The connected first outer pipes are connected by a connecting sleeve. Groundwater can be filtered by the first filter cloth, allowing pure groundwater free of silt to enter the pipe, preventing silt from clogging the pipe.

[0017] Optionally, the siphon drainage device includes an inclined drainage hole with a second outer pipe inside, and a siphon pipe inside the second outer pipe.

[0018] Optionally, a second inner tube is provided inside the second outer tube, and a second filter cloth is wrapped around the outside of the inner tube, and the siphon tube is disposed inside the second inner tube.

[0019] Optionally, a first rectangular permeable hole is provided on the first outer pipe within the semicircular area of ​​its cross-section; a permeable hole is provided on the first inner pipe within the semicircular area of ​​its cross-section, through which groundwater can enter the pipe.

[0020] Optionally, the second outer pipe includes a closed section and an open section connected together. The closed section is located at the end of the second outer pipe away from the slope, and the part of the second outer pipe other than the closed section is the open section. At the location of the open section, a second rectangular permeable hole is formed within the semi-circular area of ​​the cross-section of the second outer pipe. Groundwater enters the pipe through the permeable hole of the open section and can be stored in the closed section. Therefore, the closed section can be used as a bottom water storage area.

[0021] Optionally, the semicircular range of the cross-section includes an upper semicircle and a lower semicircle. Within the same semicircular range of the cross-section, only the upper semicircle range or the lower semicircle range is set, and the upper semicircle range and the lower semicircle range intersect each other.

[0022] Optionally, both the first outer pipe and the second outer pipe are drilled into the inclined drain hole and the downward drain hole using a pipe-following drilling method.

[0023] Optionally, the siphon pipe connects the closed section and the slope toe water collection device; the siphon pipe can draw groundwater stored in the closed section into the slope toe water collection device, which is beneficial to the continuity and stability of the siphon effect.

[0024] Optionally, the slope toe water collection device includes a slope toe water collection well connected to the slope intercepting drainage ditch, and a road drainage connection pipe connected to the slope toe water collection well. Several slope toe water collection wells are set according to the location of the deep drainage device and the siphon drainage device. The groundwater discharged by the deep drainage device enters the slope toe water collection well through the slope intercepting drainage ditch. When the water level in the slope toe water collection well is higher than the bottom of the road drainage connection pipe, the groundwater enters the municipal drainage system through the road drainage connection pipe to prevent groundwater from overflowing onto the road surface.

[0025] Optionally, the first outer tube and the second outer tube are made of stainless steel.

[0026] Optionally, the first inner tube and the second inner tube may be selected from one or more of PVC pipe, PE pipe or plastic corrugated pipe.

[0027] Optionally, the first and second filter cloths may be made of geotextile.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) This invention systematizes deep drainage and siphon drainage systems to form a composite slope drainage system for rock slopes. First, it leverages the advantage of deep drainage holes in draining groundwater from local water storage zones in the middle and upper parts of the slope, avoiding the drawbacks of excessively long pipes and the inability to drain water from areas below the holes when using deep drainage holes for drainage in the lower part of the slope. Second, it leverages the advantage of siphon pipes in lowering relatively stable groundwater levels or draining large areas of stored water. Third, it leverages the advantage of siphon pipes in lowering the water level without requiring long pipes, avoiding the drawbacks of easily interrupted siphon action and limited head when used in the middle and upper parts of rock slopes.

[0030] (2) Connect the drainage ditches in the middle and upper parts of the slope with the water collection well of the siphon pipe at the foot of the slope to realize the water level compensation of the water collection well, which is conducive to the siphon pipe forming a continuous and stable siphon effect, and can be quickly and conveniently operated when restarting the siphon effect that has been temporarily interrupted.

[0031] (3) By combining internal and external pipelines and using self-advancing pipe drilling technology, the problems of easy collapse of the hole wall, easy blockage of the pipeline and poor durability of deep drainage holes and siphon drainage holes when used on rock slopes have been solved.

[0032] (4) The outer pipe of the deep drainage hole is set up with holes drilled around the perimeter of the pipe wall and drilled along with the pipe. After completion, the inner pipe with holes drilled in the upper half circle of the pipe wall is installed inside by insertion. This solves the problem that the part with holes drilled in the pipe wall is finally installed in the upper half circle area when the pipe rotation process is uncontrollable during the drilling of a single pipe.

[0033] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0035] Figure 1 This is a schematic diagram of a combined drainage system within a rock slope.

[0036] Figure 2 This is a schematic diagram of the cross-section of the combined drainage system within a rock slope.

[0037] Figure 3 This is a schematic diagram of the siphon drainage system within the slope.

[0038] Figure 4 Schematic diagram of the elevation of a deep drainage stainless steel pipe;

[0039] Figure 5 This is a schematic diagram of the cross-section of a deep drainage hole;

[0040] Figure 6 A schematic diagram of the elevation of a stainless steel siphon drainage pipe;

[0041] Figure 7 This is a schematic diagram of the cross-section of the siphon drainage hole.

[0042] Figure reference numerals: 1 Deep drainage device, 11 First outer pipe, 12 Inclined drainage hole, 13 First inner pipe, 14 First filter cloth, 15 First rectangular permeable hole, 16 Connecting sleeve, 2 Slope intercepting drainage ditch, 3 Siphon drainage device, 31 Second outer pipe, 32 Inclined drainage hole, 33 Second inner pipe, 34 Second filter cloth, 35 Second rectangular permeable hole, 36 Siphon pipe, 37 Bottom water storage area, 38 Closed section, 39 Open section, 4 Slope toe water collection device, 41 Slope toe water collection well, 42 Road drainage connecting pipe, 5 Slope, 6 Groundwater level within the slope, 7 Controlled water level within the slope, 8 Newly built road surface. Detailed Implementation

[0043] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0044] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0045] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention 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 positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0046] Please see Figures 1 to 7 This is a composite drainage system for rock slopes, comprising a deep drainage device 1 and a siphon drainage device 3. The deep drainage device 1 is installed in the middle and upper parts of the rock slope, and the siphon drainage device 3 is installed in the lower part of the rock slope. At least two deep drainage devices 1 are arranged in parallel, and each deep drainage device 1 is connected to a slope intercepting ditch 2 at the end closest to the slope surface. The groundwater discharged from the deep drainage device 1 is introduced into the slope toe collection well 41 of the slope toe collection device 4 through the slope intercepting ditch 2, thereby compensating for the water level in the collection well and facilitating the formation of a continuous and stable siphon effect. When the siphon drainage is interrupted and needs to be restarted, the water in the slope toe collection well 41 is appropriately pumped back to the water storage section of the siphon pipe 36 to restore the siphon effect.

[0047] The deep drainage device 1 includes a first outer pipe 11, an inclined drainage hole 12, and a first inner pipe 13. The inclined drainage hole 12 is located in the middle and upper part of the rock slope, and its inclination direction is outward. The bottom of the hole is lower than the groundwater level 6 inside the slope. The first outer pipe 11 is drilled into the inclined drainage hole 12 by a self-drilling drilling device. If the inclined drainage hole 12 is long, multiple first outer pipes 11 are connected to the bottom of the inclined drainage hole 12. The segments of the connected first outer pipes 11 are fixedly connected by threaded connecting sleeves 16. After the first outer pipe 11 is installed, a first filter cloth 14 is wrapped around the outer layer of the first inner pipe 13, and then the first inner pipe 13 is inserted into the first outer pipe 11. The first filter cloth 14 not only prevents underground sediment from entering the first inner pipe 13 and blocking the pipe channel.

[0048] The above installation method can solve the problem that when drilling a single pipe, the part of the pipe wall that is drilled is finally installed in the upper semi-circular area because the rotation of the pipe cannot be controlled, which is beneficial to the release of groundwater.

[0049] First rectangular permeable holes 15 are staggered on the surface of the first outer pipe 11. The opening range of the first rectangular permeable holes 15 is within a 180° range of the semicircle of the cross-section of the first outer pipe 11. In some embodiments of the present invention, two first rectangular permeable holes 15 are opened within a 180° range of the semicircle of the cross-section of the first outer pipe 11, and the angle range of the first rectangular permeable holes 15 is α. Using rectangular permeable holes can increase the area of ​​the openings on the outer pipe, so that more groundwater can enter the pipe within a certain period of time, thereby improving the drainage efficiency.

[0050] The first rectangular water-permeable hole 15 can be opened within the upper semicircle 180° range or the lower semicircle 180° range of the cross-section of the first outer pipe 11, with the upper semicircle range and the lower semicircle range of the cross-section intersecting each other.

[0051] Water-permeable holes are provided within the upper semicircle of the first inner tube 13 within a 180° range.

[0052] In some embodiments of the present invention, the first outer tube 11 is made of stainless steel, the first inner tube 13 can be made of PVC pipe, PE pipe or corrugated pipe, etc., and the first filter cloth 14 is made of geotextile. In field implementation, other materials with the same function can be selected for replacement according to the actual situation.

[0053] Groundwater in the middle and upper parts of the rock slope flows into the inclined drainage hole 12, enters the pipe through the first rectangular permeable hole 15 on the first outer pipe 11, and then passes through the first filter cloth 14. The sediment is filtered out of the first filter cloth 14, and the groundwater without sediment passes through the permeable hole on the first filter cloth 14 and the first inner pipe 13 and enters the first inner pipe 13. The groundwater can then be discharged outside the slope through the pipe of the first inner pipe 13. The groundwater discharged outside the slope is then introduced into the slope toe water collection device 4 through the slope intercepting drainage ditch 2 until the groundwater level 6 in the slope reaches the control water level 7 in the slope, thus completing the deep drainage process.

[0054] The siphon drainage device 3 includes a second outer pipe 31, an inclined drainage hole 32, and a second inner pipe 33. The inclined drainage hole 32 is located in the lower part of the rock slope, with its inclination direction being inward. Its head is no more than 10m, and the bottom of the hole is lower than the groundwater level 6 in the slope. The second outer pipe 31 is drilled into the inclined drainage hole 32 using a self-drilling drilling device. After the second outer pipe 31 is installed, the second inner pipe 33 can be installed inside the second outer pipe 31 according to the actual slope conditions and specific needs. Before installing the second inner pipe 33, a second filter cloth 34 is wrapped around the outer layer of the second inner pipe 33, and then the second inner pipe 33 is inserted into the second outer pipe 31 to filter out the silt in the groundwater and prevent the silt from clogging the pipe.

[0055] The second outer pipe 31 is divided into a closed section 38 and an open section 39. The closed section 38 is located near the bottom of the inclined drainage hole 32 and serves as the bottom water storage area 37. In the open section 39, the surface of the second outer pipe 31 is provided with second rectangular permeable holes 35 at intervals. The opening range of the second rectangular permeable holes 35 is within a 180° range of the semicircle of the cross-section of the second outer pipe 31. In some embodiments of the present invention, two second rectangular permeable holes 35 are opened within a 180° range of the semicircle of the cross-section of the second outer pipe 31, and the angle range of the second rectangular permeable holes 35 is α. Using rectangular permeable holes can increase the area of ​​the opening on the outer pipe, allowing more groundwater to enter the pipe within a certain time and improving the drainage efficiency.

[0056] The second rectangular water-permeable hole 35 can be opened within the upper semicircle 180° range or the lower semicircle 180° range of the cross-section of the second outer pipe 31, with the upper semicircle range and the lower semicircle range of the cross-section intersecting each other.

[0057] The second inner pipe 33 is provided with multiple siphon pipes 36. In some embodiments of the present invention, the diameter of the siphon pipes 36 is 4 mm. When the second outer pipe 31 is not provided with the second inner pipe 33, multiple siphon pipes 36 are directly provided inside the second outer pipe 31. The bottom water storage area 37 is connected to the slope toe water collection device 4 through the siphon pipes 36. The groundwater in the bottom water storage area 37 can enter the slope toe water collection device 4 through the siphon effect of the siphon pipes 36 until the groundwater level 6 in the slope reaches the control water level 7 in the slope, thus completing the siphon drainage process.

[0058] Generally, when the rock mass of the slope is relatively broken, the second inner pipe 33 is installed. Through the filtration of the second inner pipe 33, groundwater without silt can enter the siphon pipe 36 without clogging the pipe, thus extending the service life of the drainage device and reducing the frequency of maintenance and repair.

[0059] In some embodiments of the present invention, the second outer tube 31 is made of stainless steel, and the second inner tube 33 can be made of PVC pipe, PE pipe or corrugated pipe, etc.; in field implementation, other materials with the same function can be selected for replacement according to the actual situation.

[0060] The lower part of the rock slope enters the pipe through the second rectangular permeable hole 35 on the second outer pipe 31, flows into the water storage area 37 at the bottom of the hole, and is then filtered by the second filter cloth 34. The groundwater, which does not contain silt, is discharged outside the slope through the siphon effect of the siphon pipe 36 in the second inner pipe 33 and enters the slope toe water collection device 4. The second filter cloth 34 is made of geotextile. In actual implementation, other materials with the same function can be selected for replacement according to the actual situation.

[0061] The slope toe water collection device 4 is set at the junction of the rock slope surface 5 and the newly built road surface 8, that is, at the toe of the rock slope. It includes a slope toe water collection well 41 and a road drainage connection pipe 42. The slope toe water collection well 41 is connected to the slope intercepting drainage ditch 2 and the road drainage connection pipe 42 respectively. Several slope toe water collection wells 41 are set according to the location of the deep drainage device 1 and the siphon drainage device 3. The road drainage connection pipe 42 is connected to the municipal drainage system.

[0062] The groundwater discharged by the deep drainage device 1 and the siphon drainage device 3 flows into the slope foot collection well 41. When the water level in the slope foot collection well 41 is higher than the bottom of the road drainage connection pipe 42, the water in the slope foot collection well 41 will flow into the municipal drainage system through the road drainage connection pipe 42 to prevent the water level in the slope foot collection well 41 from being too high and overflowing onto the road surface.

[0063] The composite drainage system for rock slopes of this invention replaces the previous single drainage method with a composite one. Deep drainage is used in the middle and upper parts of the rock slope, while siphon drainage is used in the lower part. Finally, the two drainage methods are connected, and the groundwater discharged from the deep drainage holes is introduced into the collection well of the siphon drainage hole at the toe of the slope through the intercepting drainage ditch on the slope surface, so that the siphon drainage can form a continuous and stable siphon effect.

[0064] Example:

[0065] A combined deep-water drainage and siphon drainage system for rock slopes is disclosed. It includes a deep-water drainage device 1 and a siphon drainage device 3. The deep-water drainage device 1 is installed in the middle and upper parts of the rock slope, while the siphon drainage device 3 is installed in the lower part. At least two deep-water drainage devices 1 are arranged side-by-side, and each deep-water drainage device 1 is connected to a slope intercepting ditch 2 at its end closest to the slope surface. Groundwater discharged from the deep-water drainage device 1 is introduced into the slope toe collection well 41 of the slope toe collection device 4 through the slope intercepting ditch 2, achieving water level compensation in the collection well and facilitating a continuous and stable siphon effect. When the siphon drainage is interrupted and needs to be restarted, the water in the slope toe collection well 41 is appropriately pumped back to the water storage section of the siphon pipe 36 to restore the siphon effect.

[0066] like Figure 2As shown: The mountain slope is a rock slope. In rock slopes, groundwater is mainly distributed in the upper and middle rock strata, joints and fissures, and the bottom area of ​​the slope. Drainage is carried out in the upper part of the slope using inclined drainage holes 12 with a diameter of 250mm and a length of 25-50m. The inclined drainage holes 12 are all inserted into the slope to control the water level below 7. The drainage holes are arranged with a horizontal spacing of 4.0m and a vertical spacing of 8.0m, with a slope of 5% outward. A 250mm first outer pipe 11 is installed inside the inclined drainage hole 12. The pipe is drilled with a self-drilling device. The first outer pipe 11 is made of stainless steel with a wall thickness of 5mm. The surface of the first rectangular permeable hole 15 with a diameter of 100×20mm is opened. The permeable holes are staggered at 100mm intervals. The opening range is within 180° of the semicircle of the cross-section of the first outer pipe 11. This range includes the upper and lower semicircles of the cross-section. The first rectangular permeable hole 15 is located in the upper or lower semicircle of the cross-section, with the upper and lower semicircles of the cross-section intersecting each other. The angle range of the first rectangular permeable hole 15 is α = 65°. Because the rock mass in the upper and middle parts of the rock slope is relatively fractured, a first inner pipe 13 with a diameter of 200mm needs to be installed inside the first outer pipe 11. Water-permeable holes are provided within a 180° range of the upper semicircle above the horizontal line of the center of the cross-section of the first inner pipe 13. In this embodiment, the first inner pipe 13 is made of PVC pipe, and the first outer pipe 11 is made of stainless steel pipe. The outer sheath of the first inner pipe 13 has a weight of 300g / m². 2 The first filter cloth 14 is made of geotextile to filter out the silt in the groundwater, allowing only the filtered groundwater without silt to enter the inner pipe, thus preventing silt from clogging the pipe; the rectangular permeable holes are used to increase the passage of groundwater into the pipe and accelerate the discharge of groundwater.

[0067] A siphon drainage device 3 is used for drainage at the lower part of the rock slope. The device's inclined drainage holes 32 are arranged 2m below the lowest row of inclined drainage holes 12 on the slope surface 5. A row of inclined drainage holes 32 is set on the slope surface 5, with a horizontal spacing of 4m, a hole diameter of 180mm, and a vertical height of 10m. The hole angle is approximately perpendicular to the slope surface 5. A second outer pipe 31 with a diameter of 180mm is installed inside the inclined drainage holes 32. The second outer pipe 31 is drilled using a self-drilling device. Its wall thickness is 5mm, and it is divided into a closed section 38 and an open section 39. The bottom 2m of the second outer pipe 31 is the closed section 38, and the rest is the open section 39. The bottom closed section 38 is used as a bottom water storage area 37. The top of the bottom water storage area 37 needs to be lower than the surrounding area. The water level 7 is controlled within the slope to ensure the stability of the water level in the storage area and maintain the siphon effect. A second rectangular permeable hole 35 of 80×16mm is opened on the surface of the opening section 39. The permeable holes are arranged alternately with a spacing of 100mm. The opening range is within 180° of the semicircle of the cross-section of the second outer pipe 31. This range includes the upper semicircle and the lower semicircle of the cross-section. The second rectangular permeable hole 35 is set in the upper semicircle or the lower semicircle of the cross-section, wherein the upper semicircle and the lower semicircle of the cross-section are interleaved, and the angle range of the second rectangular permeable hole 35 is a=65°. In this embodiment, the second outer pipe 31 is made of stainless steel. The rectangular permeable hole can increase the channel for groundwater to enter the pipe and accelerate the discharge of groundwater.

[0068] Because the rock mass at the bottom of the rock slope is relatively fractured, a second inner pipe 33 with a diameter of 160mm is installed inside the second outer pipe 31. In this embodiment, the second inner pipe 33 is made of PVC pipe, and the outer sheath of the second inner pipe 33 has a weight of 300g / m³. 2 The second filter cloth 34 is made of geotextile. The second inner pipe 33 also contains six siphon pipes 36 with a diameter of 4mm, which connect to the slope toe water collection device 4. Simultaneously, groundwater discharged from the deep drainage device 1 is introduced into the slope toe water collection well 41 of the slope toe water collection device 4 through the slope intercepting drainage ditch 2 arranged on the slope, thus compensating for the water level in the well. Furthermore, the slope toe water collection well 41 is connected to both the slope intercepting drainage ditch 2 and the road drainage connection pipe 42, which is connected to the municipal drainage system. When the water level in the slope toe water collection well 41 is higher than the bottom of the road drainage connection pipe 42, the water overflows into the municipal drainage system. After the implementation of this composite drainage system, the groundwater level on the slope is significantly reduced, effectively improving slope stability and suppressing slope seepage and deformation.

[0069] In summary, in this embodiment, the technical solution of the present invention effectively solves the shortcomings of deep drainage hole walls being prone to collapse and blockage, having poor durability, and being unable to drain water in the area below the hole. At the same time, it solves the defects of siphon drainage being prone to interruption and having limited head. It systematizes deep drainage and siphon drainage into a composite slope drainage system for rock slopes. The water discharged from the deep drainage holes is used to compensate for the water level in the collection well, which facilitates the formation of a continuous and stable siphon effect by the siphon pipe 36.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A composite drainage system for rock slopes, installed on the slope surface (5), comprising a deep drainage device (1) and a siphon drainage device (3), characterized in that: The siphon drainage device (3) is located below the deep drainage device (1). The deep drainage device (1) is connected to a slope intercepting drainage ditch (2) at one end near the slope (5). A slope foot water collection device (4) is connected below the siphon drainage device (3). The drainage from the slope intercepting drainage ditch (2) is introduced into the slope foot water collection device (4). The deep drainage device (1) includes an inclined drainage hole (12), inside which a first outer pipe (11) is installed by drilling. A first inner pipe (13) is installed inside the first outer pipe (11), and a first filter cloth (14) is wrapped around the outside of the first inner pipe (13). A first rectangular water-permeable hole (15) is opened in the semi-circular area of ​​the cross-section of the first outer pipe (11). A water-permeable hole is opened in the semi-circular area of ​​the cross-section of the first inner pipe (13). The siphon drainage device (3) includes an inclined drainage hole (32), inside which a second outer pipe (31) is provided, and a siphon pipe (36) is provided inside the second outer pipe (31); the second outer pipe (31) includes a closed section (38) and an open section (39) connected together, the closed section (38) is provided at one end of the second outer pipe (31) away from the slope (5), and is used as a bottom water storage area (37); a second inner pipe (33) is provided inside the second outer pipe (31), and a second filter cloth (34) is wrapped around its outside, and the siphon pipe (36) is provided inside the second inner pipe (33), and the bottom water storage area (37) is connected to the slope foot water collection device (4) through the siphon pipe (36); the water discharged by the inclined drainage hole (12) is used to compensate the water level of the slope foot water collection device (4), so that the siphon pipe (36) can form a continuous and stable siphon effect.

2. The composite drainage system within a rock slope according to claim 1, characterized in that: The first inner tube (13) is selected from one or more of PVC pipe, PE pipe or plastic corrugated pipe.

3. The composite drainage system within a rock slope according to claim 1, characterized in that: The second inner tube (33) is a group formed by any one or more of PVC pipe, PE pipe or plastic corrugated pipe.

4. The composite drainage system within a rock slope according to claim 1, characterized in that: At the opening section (39), a second rectangular water-permeable hole (35) is provided within the semi-circular cross-section of the second outer tube (31).

5. The composite drainage system within a rock slope according to claim 4, characterized in that: The drainage in the siphon (36) is introduced from the closed section (38) to the slope foot water collection device (4).

6. The composite drainage system within a rock slope according to claim 1, characterized in that: The slope toe water collection device (4) includes a slope toe water collection well (41) connected to the slope intercepting drainage ditch (2), and also includes a road drainage connection pipe (42) connected to the slope toe water collection well (41); the drainage in the slope toe water collection well (41) is introduced into the external drainage system through the road drainage connection pipe (42).

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