Drainage Anti-Slide Pipe Pile Suitable for Open Channel Project of Expansive Soil in Cold and Arid Regions and Construction Method Thereof

This application is based upon and claims priority to Chinese Patent Application No. 202410350399.X, filed on Mar. 26, 2024, the entire contents of which are incorporated herein by reference.

The present invention belongs to the technical field of water conservancy project construction, and specifically relates to a drainage anti-slide ecological pipe pile suitable for an open channel project of expansive soil in cold and arid regions and a construction method thereof, which are suitable for preventing landslide disasters of expansive soil slopes in water conservancy project construction, and is particularly suitable for expansive soil slopes in cold and arid regions.

The seasonal changes in Xinjiang region of China are very obvious: hot in summer, cold in winter, rapid temperature increase in spring, and rapid temperature decrease in autumn. Especially in northern Xinjiang, the adverse effects of climate factors on the construction, operation and maintenance of water conservancy project are more obvious. In the changing seasons of the year, after the end of summer, the shutdown period comes, the channel water level drops rapidly and eventually empties, the temperature drops rapidly in autumn and reaches the lowest in winter, and the operational period begins again in the middle of the following spring. Expansive soil channels located in cold and arid regions also experience significant dry-wet-freeze-thaw cycles under the influence of climate.

The instability failure mechanism of the expansive soil slope is as follows: during the annual operational period, the seepage water infiltrates the channel slope and makes the expansive soil saturated with water, showing an expansion trend; and with the end of the operational period, the seepage water level gradually decreases, and the shrinkage of the expansive soil due to water loss can easily lead to cracks in the shallow soil. However, due to the slow discharge of seepage water behind the channel slope and the rapid decrease in temperature during the shutdown period in autumn and winter, the seepage water still remained in the channel slope is easy to freeze into ice crystals, which further expands the soil body from the saturated state, destroys the original structure of the soil body, and reduces the strength of the soil body framework. Finally, before the end of winter and the beginning of the operational period in spring, the frozen ice crystals melt and are discharged in the form of seepage water, but the shallow and deep cracks in the soil body of the channel slope that have been caused cannot be repaired, and continue to develop in several cycles, eventually leading to the destruction of the channel slope structure. It can be seen from the failure mechanism that the slope problems induced by a dry-wet cycle, a freeze-thaw cycle, and a dry-wet-freeze-thaw cycle are all related to the water level of the seepage water behind the membrane, which is crucial to the control and drainage of the seepage water level behind the membrane for an open channel project. Although a box culvert water collection structure has been provided at the bottom of the channel for the seepage channel project behind the canal, the effect is poor. Therefore, there is a need for a drainage anti-slide ecological pile suitable for expansive soil slopes in cold and arid regions to solve the project problems and to greatly avoid the occurrence of shallow landslides and frost heave damage to expansive soil channels.

An anti-slide pile, as a retaining structure that has been widely used in slope anti-slide treatment for a long time, is the main measure for landslide control. The anti-slide pile is buried in the stable slide bed, transfer the landslide thrust to the stable stratum by relying on the mutual clamping effect between the piles and the rock (soil) around the piles, and stabilizes the landslide by the anchoring effect and anti-slide force of the pile body embedded in the stable rock stratum. After many scholars conducted targeted research and improvements on anti-slide piles, various types of drainage anti-slide piles were proposed. Compared with conventional anti-slide piles, drainage anti-slide piles have solved the problem of soil infiltration and drainage to a certain extent, while also retaining the landslide control function of anti-slide piles. Although different types of drainage anti-slide piles have been proposed and improved, most of which are based on composite foundation design. There is a lack of drainage anti-slide pile design suitable for open channel water transfer projects, and the problem of water seepage behind the slope is still an unresolved problem.

To overcome the defects in the prior art, the present invention provides a drainage anti-slide ecological pipe pile suitable for an open channel project of expansive soil in cold and arid regions and a construction method thereof, which can improve the stability of the channel slope by timely pumping out seepage water behind the channel slope to control the water level behind the slope.

To achieve the foregoing objective, the present invention adopts the following technical solutions.

A drainage anti-slide pipe pile suitable for an open channel project of expansive soil in cold and arid regions includes a pile body, wherein the pile body is provided with a dewatering section and an embedded section arranged up and down, a wall of the dewatering section of the pile body is provided with a plurality of drainage channels for consolidation drainage; and the embedded section of the pile body is embedded in a solid rock stratum to provide an anti-slide effect.

Further, a pile cover is arranged on one side of the dewatering section of the pile body far away from the embedded section, so as to prevent soil particles from entering the interior of the pipe pile.

Further, the dewatering section, the embedded section and the pile cover of the pile body are all cast with steel slag concrete.

Further, a geomembrane is attached to an inner wall of the pile body.

Further, a water pumping channel is arranged at one end of the dewatering section of the pile body close to the embedded section.

Further, a ratio of the total area of the plurality of drainage channels to the side area of the pile body is less than 0.03; the plurality of drainage channels are arranged along the long direction of the pile body at a spacing of 0.5 m; and a diameter of the drainage channel is 1/10 of an outer diameter of the pile body.

Further, when arranged at the top of a channel slope, the drainage anti-slide pipe pile further includes an automatic water pumping and drainage device, the automatic water pumping and drainage device includes a water pumping and drainage pipe positioned in the pile body, one end of the water pumping and drainage pipe extends to the embedded section, and the other end of the water pumping and drainage pipe extends to an outer side of the pile body and is connected to a water pump.

Further, a plurality of water level sensors are arranged from top to bottom on an inner side wall of the dewatering section of the pile body, the plurality of water level sensors are electrically connected to a water level controller, and the water level controller is electrically connected to the water pump.

A construction method of a drainage anti-slide pipe pile suitable for an open channel project of expansive soil in cold and arid regions is a construction method of the drainage anti-slide pipe pile suitable for the open channel project of expansive soil in cold and arid regions according to any one of the above aspects in the middle of a channel slope, and includes the following steps:

S: performing on-site surveying and mapping, and determining a piling location and a length of a drainage anti-slide ecological pile according to the on-site water level and channel slope data during an operational period;

S: according to the determined piling position, drilling a hole by rotary drilling, the hole extending to a water pumping pipe of a box culvert structure at the bottom of the channel, then hoisting the pile to the drilling position, slowly piling, lowering the embedded section and the dewatering section of the pile body in sections, hoisting the embedded section of the pipe pile body to align with a construction hole, checking a verticality of the pipe pile body during the piling process, controlling a vertical deviation to be less than or equal to 0.5% when a first section of the pile body and the embedded section are inserted into the ground, starting to press the pile after the requirements are met, stopping the pile delivering when the embedded section is lowered to 1000 mm above the soil body, and completing the laying of a geomembrane on the inner wall of the pipe pile in advance before sinking the pipe pile;

S: hoisting the dewatering section of the pipe pile body to the piling position, welding the dewatering section and the embedded section into an integral structure after checking the verticality of the pile body, checking the verticality of the welded integral pile body, and completing the pile delivering process; and

S: after the pile delivering process is completed, connecting a pre-buried drainage pipe with the hole of the dewatering section, pouring steel slag concrete into the pipe pile, and mounting the pile cover made of the steel slag concrete after the short pile is poured and cured.

A construction method of a drainage anti-slide pipe pile suitable for an open channel project of expansive soil in cold and arid regions is a construction method of the drainage anti-slide pipe pile suitable for the open channel project of expansive soil in cold and arid regions according to any one of the above aspects in the top of a channel slope, and includes the following steps:

S: performing on-site surveying and mapping, and determining a piling location and a length of a drainage anti-slide ecological pile according to the on-site water level and channel slope data during an operational period;

S: arranging a water level sensor on the inner wall of the dewatering section of the pipe pile in advance before pile delivering, and connecting the other end of the sensor with the water level controller;

S: according to the determined piling position, drilling a hole by rotary drilling, the hole extending to a water pumping pipe of a box culvert structure at the bottom of the channel, then hoisting the pile to the drilling position, slowly piling, lowering the embedded section and the dewatering section of the pile body in sections, hoisting the embedded section of the pipe pile body to align with a construction hole, checking a verticality of the pipe pile body during the piling process, controlling a vertical deviation to be less than or equal to 0.5% when a first section of the pile body and the embedded section are inserted into the ground, starting to press the pile after the requirements are met, stopping the pile delivering when the embedded section is lowered to 1000 mm above the soil body;

S: hoisting the dewatering section of the pipe pile body to the piling position, welding the dewatering section and the embedded section into an integral structure after checking the verticality of the pile body, checking the verticality of the welded integral pile body, and completing the pile delivering process; and

S: after the pile delivering process is completed, connecting a pre-buried drainage pipe with the hole of the dewatering section, pouring steel slag concrete into the pipe pile, and mounting the pile cover made of the steel slag concrete after the short pile is poured and cured. The beneficial effects of the present invention are as follows.

1. Compared with the conventional drainage anti-slide pile, the present invention is more targeted at the expansive soil channel project in cold and arid regions, which can effectively control seepage water level behind a channel slope in an operational period, quickly reduces lagging dewatering level behind the slope in the initial stage of a shutdown period, and improves the stability of the entire slope.

2. The concrete doped steel slag adopted by the drainage pipe pile of the present invention is a byproduct in the steel-making process, and the concrete doped steel slag is recycled to manufacture the drainage anti-slide pipe pile, so that the on-site environment-friendly disposal and recycling of steel slag waste are achieved, and the ecological protection effect is achieved.

3. The automatic water pumping and drainage device adopted by the present invention is used to quickly reduce the lagging seepage water level behind the channel slope in the initial stage of a shutdown period, can also be used to control the seepage water level behind the channel slope in the operational period, which can greatly reduce the adverse effect of the seepage water behind the channel slope on the stability of the channel slope.

In the drawings,: dewatering section;: embedded section;: pile body;: pile cover;: PVC drainage pipe;: geomembrane of dewatering section;: geomembrane of embedded section;: drainage channel;: water level sensor;: pile top water pumping port;: water pumping channel;: water pumping and drainage pipe; and: automatic water pumping and drainage device.

The present invention provides a drainage anti-slide pipe pile suitable for an open channel project of expansive soil in cold and arid regions and a construction method thereof. The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings, so as to make the technical solutions easier to understand and grasp.

Referring to, a drainage anti-slide pipe pile suitable for an open channel project of expansive soil in cold and arid regions includes a pile body, wherein the pile bodyis provided with a dewatering sectionand an embedded sectionarranged up and down, a wall of the dewatering sectionof the pile bodyis provided with a plurality of drainage channelsfor consolidation drainage; and the embedded sectionof the pile bodyis embedded in a solid rock stratum to provide an anti-slide effect.

In this embodiment, a pile coveris arranged on one side of the dewatering sectionof the pile bodyfar away from the embedded section, so as to prevent soil particles from entering the interior of the pipe pile.

In this embodiment, the dewatering section, the embedded sectionand the pile coverof the pile bodyare all cast with steel slag concrete.

The dewatering sectionand the embedded sectionof the pile bodyare welded into an integrated structure, wherein the length of the dewatering sectionmay be cut according to the actual working conditions of the channel.

Preferably, the connection between the dewatering sectionand the embedded sectionof the pile bodyand the connection between the dewatering sectionsare prefabricated with welding connectors.

The embedded sectionof the pile bodyis a short pile cast with steel slag concrete. The steel slag concrete is cast after the embedded sectionis driven into the soil, and the entire pile body is embedded through the consolidation effect of the steel slag concrete during the pile forming process.

In this embodiment, steel slag concrete is used for casting, so that the problem of waste treatment in the production of a part of steel products is solved, and the ecological protection function is achieved.

In this embodiment, a geomembrane is attached to an inner wall of the pile body.

Specifically, the pile wall of the dewatering sectionof the pile bodyis attached with a geomembraneof the dewatering sectionclose to the inner wall of the pile body, and the pile wall of the embedded sectionof the pile bodyis attached with a geomembraneof the embedded sectionclose to the inner wall of the pipe pile, as so to prevent soil particles from flowing into the pile body.

In this embodiment, a water pumping channelis arranged at one end of the dewatering sectionof the pile bodyclose to the embedded section.

Specifically, a PVC drainage pipeis provided on the water pumping channel.

In this embodiment, a ratio of the total area of the plurality of drainage channelsto the side area of the pile bodyis less than 0.03; the plurality of drainage channelsare arranged along the long direction of the pile bodyat a spacing of 0.5 m; and a diameter of the drainage channelis 1/10 of an outer diameter of the pile body.

Specifically, the opening ratio of drainage channelin the pile body should be limited according to the pile body bearing capacity requirements. The actual opening ratio value may be limited according to different actual project requirements, but it is recommended to be controlled within 3.0% based on construction experience, that is, the ratio of the total opening area to the side area of the pipe pile is controlled within 0.03. The opening diameter is reduced and the number of opening layers is increased under the condition of controlling the total opening area. The opening positions are evenly and symmetrically arranged along the pipe pile of the dewatering section. The drainage channelis opened every 0.5 m along the pile length, that is, starting from the pile end, the channels are arranged in sequence along the pile length of 0.5 m, 1.0 m, 1.5 m, 2.0 m, and the like. According to construction experience, the opening diameter is selected as 1/10 of the outer diameter of the pipe pile, that is, the hole diameter is 100 mm.

The drainage anti-slide pipe piles provided by this embodiment are arranged at the top and the middle of the channel slope according to the drainage function and the setting position.

When the pipe pile is arranged in the middle of the channel slope, the water collected in the pipe piles is discharged into the box culvert at the bottom of the channel by gravity.

When arranged at the top of the channel slope, the drainage anti-slide pipe pile provided by this embodiment further includes an automatic water pumping and drainage device, the automatic water pumping and drainage deviceincludes a water pumping and drainage pipepositioned in the pile body, one end of the water pumping and drainage pipeextends to the embedded section, and the other end of the water pumping and drainage pipe extends to an outer side of the pile bodyand is connected to a water pump; and the pumping and drainage is performed by the automatic water pumping and drainage device.

The pile coveris provided with a pile top water pumping portin advance for the water pumping and drainage pipeto pass through.

A plurality of water level sensorsare arranged from top to bottom on an inner side wall of the dewatering sectionof the pile body, the plurality of water level sensorsare electrically connected to a water level controller, and the water level controller is electrically connected to the water pump.

Specifically, the automatic water pumping and drainage devicecan sense the water level in the pipe pile through the water level sensor, and automatically pump and drain after reaching the set drainage level, which can intelligently maintain the water level in the pipe pile so as to control the seepage water level behind the channel slope.