Draining pile and draining method for deep and thick liquefied soil layer

Abstract

The application relates to the technical field of liquefied soil layer drainage, and discloses a drainage pile and a drainage method for deep thick liquefied soil layers, the drainage pile comprising: a gravel pile body arranged in the liquefied soil layer; a composite water collecting pipe arranged in the gravel pile body, comprising an inner pipe and an outer pipe arranged at the outer periphery of the inner pipe, the side wall of the outer pipe being provided with a plurality of water passing holes, an annular water collecting cavity being formed between the inner pipe and the outer pipe, and the bottom of the inner pipe being provided with a through hole communicated with the water collecting cavity; a negative pressure generating device communicated with the water collecting cavity and used for generating a negative pressure environment in the water collecting cavity; a drainage device with one end extending into the inner pipe and used for draining water in the inner pipe; and a water level monitoring device arranged in the inner pipe and connected with the controller of the negative pressure generating device, which triggers the negative pressure generating device to start when the water level in the inner pipe rises to a first position. The drainage pile and the drainage method combine negative pressure pumping and drainage with automatic control, realize the rapid collection and efficient drainage of pore water in deep liquefied soil.

Description

Technical Field

[0001] This invention relates to the field of drainage technology for liquefied soil layers, specifically to a drainage pile and drainage method for deep liquefied soil layers. Background Technology

[0002] Deep, saturated sandy and silty soils are prone to liquefaction under seismic loads. The main mechanism lies in the rapid accumulation of excess pore water pressure within the soil during seismic vibrations, leading to a significant reduction in effective stress. This, in turn, causes a decrease in soil strength and stiffness, resulting in engineering disasters such as foundation settlement, lateral displacement, and even overall instability. Currently, crushed stone piles are widely used in liquefaction foundation treatment projects because they combine the functions of enhancing foundation bearing capacity and drainage consolidation. When an earthquake causes soil liquefaction, crushed stone piles can act as drainage channels to promote the dissipation of excess pore water pressure, thereby improving the liquefaction resistance of the foundation soil. Therefore, the efficiency of pore water pressure dissipation after liquefaction largely depends on the drainage performance of the crushed stone piles.

[0003] However, traditional crushed stone pile drainage technology still has shortcomings in deep liquefiable soil layers. The drainage path in deep soil layers is long, and the drainage resistance in deeper areas is significant, leading to a marked decrease in drainage efficiency. Furthermore, traditional drainage methods mainly rely on the natural seepage field formed between the soil and the crushed stone piles for drainage. However, deep liquefiable soil layers typically have low permeability coefficients, and gravity seepage alone is insufficient to rapidly release excess pore water pressure, failing to meet the need for rapid post-earthquake recovery of foundation stability. Simultaneously, existing drainage piles generally lack active drainage capabilities and intelligent response mechanisms, making it difficult to promptly initiate the drainage process after liquefaction occurs, and unable to precisely control the drainage intensity based on changes in groundwater level. This can easily lead to insufficient drainage or excessive precipitation, thereby affecting the foundation treatment effect and potentially causing risks to the surrounding environment.

[0004] Therefore, there is an urgent need to develop a new type of drainage structure that can achieve active pumping, intelligent control and efficient drainage, so as to improve the dissipation efficiency of excess pore water pressure in deep liquefiable soil layers and the liquefaction resistance of the foundation. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a drainage pile and drainage method for deep liquefiable soil layers. By combining active negative pressure pumping with automatic control, it achieves rapid collection and efficient discharge of pore water in deep liquefiable soil, thereby improving the bearing capacity and liquefaction resistance of the foundation.

[0006] According to one embodiment of the present invention, a drainage pile for a deep liquefiable soil layer is provided, comprising: a crushed stone pile body disposed in the liquefiable soil layer; a composite water collection pipe disposed in the crushed stone pile body, including an inner pipe and an outer pipe disposed around the outer periphery of the inner pipe, the side wall of the outer pipe having a plurality of water passage holes, an annular water collection cavity being formed between the inner pipe and the outer pipe, and a through hole communicating with the water collection cavity being provided at the bottom of the inner pipe; a negative pressure generating device connected to the water collection cavity for generating a negative pressure environment in the water collection cavity; a drainage device extending one end into the inner pipe for discharging water from the inner pipe; and a water level monitoring device disposed in the inner pipe and connected to the controller of the negative pressure generating device, wherein the negative pressure generating device is triggered to start when the water level in the inner pipe rises to a first position.

[0007] In one embodiment, the composite water collection pipe is vertically arranged at the center of the crushed stone pile.

[0008] As one implementation, a check valve is provided at the through hole, which controls the water flow from the water collection chamber to the inner pipe in one direction.

[0009] In one embodiment, the negative pressure generating device includes a suction pipe, a vacuum pump, an AC contactor, and a switch. One end of the suction pipe is connected to the vacuum pump, and the other end is connected to the upper end of the water collection chamber.

[0010] In one embodiment, the water level monitoring device includes a float that swings up and down at the first position. The upper end of the float is connected to the gate valve. When the float moves up, it closes the gate valve, and when the float moves down, it opens the gate valve.

[0011] In one embodiment, the water level monitoring device includes a liquid level sensor connected to the drainage device, the liquid level sensor being disposed at a second position in the inner pipe, and the drainage device being configured to initiate drainage when the water level in the inner pipe reaches the second position.

[0012] In one embodiment, the drainage device includes a siphon pipe and a solenoid valve mounted on the siphon pipe. One end of the siphon pipe is submerged in the water within the inner pipe, and the other end extends beyond the drainage pile at a height lower than the second position. The liquid level sensor is connected to the controller of the solenoid valve. When the water level in the inner pipe is higher than the second position, the controller controls the solenoid valve to open; when the water level in the inner pipe is lower than the second position, the controller controls the solenoid valve to close.

[0013] In one implementation, the second position is lower than the first position.

[0014] According to one embodiment of the present invention, a drainage method is provided, which employs the drainage piles for deep liquefiable soil layers as described above, and includes the following steps: S1, monitoring the water level in the inner pipe, and when the water level in the inner pipe is higher than a second position, activating the drainage device to discharge the water in the inner pipe outward; S2, when the water level in the inner pipe continues to rise and exceeds a first position, activating the negative pressure generating device to generate a negative pressure environment in the water collection chamber, accelerating the collection of water around the drainage pile into the water collection chamber; S3, when the water level in the inner pipe is equal to or lower than the second position, shutting off the drainage device.

[0015] In one implementation, when the water level in the inner pipe is higher than the first position, the drainage rate of the drainage device is a first rate; when the water level in the inner pipe is higher than the second position and lower than the first position, the drainage rate of the drainage device is a second rate; the first rate is greater than the second rate.

[0016] Based on the above description and practical application, this invention combines negative pressure drainage technology with a crushed stone pile drainage structure, constructing a composite water collection pipe inside the crushed stone pile to achieve directional collection and efficient discharge of groundwater in deep liquefied soil layers. Compared to traditional drainage methods that rely on natural seepage, this invention can significantly shorten drainage time and increase the dissipation rate of excess pore water pressure.

[0017] Furthermore, by incorporating a water level monitoring device and an automatic control mechanism, this invention enables the drainage device and negative pressure generating device to automatically start and stop based on changes in the water level within the liquefiable soil layer. This provides excellent intelligent response capabilities, avoiding the problems of manual intervention and excessive precipitation. This technology effectively solves the problems of low drainage efficiency and difficulty in accurately controlling drainage volume in deep liquefiable soil layers using traditional drainage piles. It enables continuous, rapid, and safe release of deep pore water pressure, significantly improving the liquefaction resistance and post-earthquake stability of the foundation soil.

[0018] Furthermore, the drainage piles of this invention have a simple structure, compact layout, and high degree of automation, and have good engineering applicability and promotion value. They can be widely used in the fields of foundation reinforcement and disaster prevention engineering in earthquake liquefaction zones. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a drainage pile for a deep liquefiable soil layer according to one embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the crushed stone pile in a drainage pile for a deep liquefied soil layer, according to one embodiment of the present invention.

[0021] Figure 3 This is a schematic flowchart of a drainage method according to one embodiment of the present invention.

[0022] The attached figures are labeled as follows: 1. Crushed stone pile body; 2. Composite water collection pipe; 21. Inner pipe; 22. Outer pipe; 23. Water collection chamber; 24. Water passage hole; 25. Through hole; 26. Check valve; 31. Suction pipe; 32. Vacuum pump; 33. AC contactor; 34. Knife gate; 41. Siphon pipe; 42. Solenoid valve; 51. Float ball; 52. Liquid level sensor. Detailed Implementation

[0023] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0024] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. It should be noted that in this disclosure, the terms "comprising," "configured with," and "set in" are used to indicate an open-ended inclusion, meaning that additional elements / components / etc. may exist besides those listed; the terms "first," "second," etc., are used only as labels and are not intended to limit the number or order of objects; the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the 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, and therefore should not be construed as a limitation of the invention.

[0025] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] like Figure 1 and Figure 2 As shown in the figure, in this embodiment, a drainage pile for a deep liquefiable soil layer is disclosed, including a crushed stone pile body 1, a composite water collection pipe 2, a negative pressure generating device, a drainage device and a water level monitoring device.

[0027] The crushed stone pile 1 is installed in the liquefiable soil layer and serves as the main structure of the drainage pile. It is filled with crushed stone and has good permeability and a certain bearing capacity. The crushed stone pile 1 forms a drainage channel in the liquefiable soil layer, allowing excess pore water in the liquefied soil layer to seep into the interior of the crushed stone pile 1 through the pores between the crushed stones.

[0028] The composite water collection pipe 2 is vertically positioned at the center of the crushed stone pile body 1, comprising an inner pipe 21 and an outer pipe 22 surrounding the inner pipe 21. The diameter of the outer pipe 22 is larger than that of the inner pipe 21, and the outer pipe 22 is fitted around the outer circumference of the inner pipe 21, forming an annular water collection cavity 23 between them. Several water passage holes 24 are provided on the side wall of the outer pipe 22, allowing water seeping into the crushed stone pile body 1 from the liquefiable soil layer to enter the water collection cavity 23 through the water passage holes 24. A through hole 25 communicating with the water collection cavity 23 is provided at the bottom of the inner pipe 21, allowing water collected in the water collection cavity 23 to flow into the inner pipe 21 through the through hole 25. The composite water collection pipe 2, vertically positioned at the center of the crushed stone pile body 1, can uniformly collect water seeping into the soil layer from all directions, and, with the help of the structure of the water collection cavity 23 and the inner pipe 21, achieve graded collection and directional flow of groundwater. In addition, the composite water collection pipe 2 is set vertically in the center of the crushed stone pile 1, and can also support the crushed stone pile 1 with the help of the outer pipe 22, which can improve the radial compressive strength of the crushed stone pile 1 to a certain extent.

[0029] In this embodiment, a check valve 26 is provided at the through hole 25. The check valve 26 controls the water flow from the water collection chamber 23 to the inner pipe 21 in one direction, preventing the water collected in the inner pipe 21 from flowing back to the water collection chamber 23 and the outside of the crushed stone pile 1 due to pressure changes, thus ensuring the stability and one-wayness of the drainage process.

[0030] In this embodiment, the through hole 25 is provided on the lower end face of the inner tube 21. When the water level in the water collection chamber 23 is low, the water collection chamber 23 and the inner tube 21 can still be connected through the through hole 25 at the bottom of the inner tube 21, ensuring that the water in the water collection chamber 23 can be continuously discharged into the inner tube 21, thereby improving drainage efficiency.

[0031] The negative pressure generating device is connected to the water collection chamber 23 to create a negative pressure environment within the chamber, accelerating the collection of water from the liquefied soil surrounding the drainage pile. The drainage device discharges the water collected in the inner pipe 21 outside the drainage pile. A water level monitoring device is located in the inner pipe 21 to monitor the water level. This device is connected to the controller of the negative pressure generating device for coordinated control of its opening and closing.

[0032] When the drainage pile used in the deep liquefiable soil layer is working, when the water level in the inner pipe 21 rises to the preset first position, the water level in the inner pipe 21 is high, indicating that the water content around the drainage pile is large. At this time, the negative pressure generating device is triggered to start, forming a negative pressure environment in the water collection chamber 23. The pressure difference is used to accelerate the water in the soil layer to gather into the composite water collection pipe 2, which can actively improve the drainage efficiency.

[0033] In this embodiment, the negative pressure generating device includes a suction pipe 31, a vacuum pump 32, an AC contactor 33, and a switch 34. One end of the suction pipe 31 is connected to the vacuum pump 32, and the other end is connected to the upper end of the water collection chamber 23. The vacuum pump 32, the AC contactor 33, and the switch 34 are arranged in the same circuit. When the switch 34 is closed, the vacuum pump 32 is energized and starts, drawing gas out of the water collection chamber 23 through the suction pipe 31, creating a negative pressure environment in the water collection chamber 23. This drives the excess pore water in the surrounding liquefied soil layer to accelerate and seep into the water collection chamber 23 along the pressure gradient direction. The AC contactor 33 and the switch 34 are used to control the start and stop of the vacuum pump 32, which is triggered by the water level monitoring device to achieve automatic control.

[0034] Specifically, in this embodiment, the water level monitoring device includes a float 51 that swings up and down at a first position in the inner pipe 21. The upper end of the float 51 is connected to a gate 34. When the water level in the inner pipe 21 rises to the first position, the float 51 moves up with the water surface, causing the gate 34 to close, which in turn energizes the AC contactor 33, drives the vacuum pump 32 to start, generates negative pressure in the water collection chamber 23, and accelerates the collection of water from the surrounding soil layer into the water collection chamber 23. When the water level drops, the float 51 moves down, the gate 34 opens, the vacuum pump 32 stops working, and the drainage rate is reduced, which can prevent the soil water level from dropping excessively.

[0035] Furthermore, in this embodiment, the water level monitoring device also includes a liquid level sensor 52. The liquid level sensor 52 is located at the second position of the inner pipe 21 and is connected to the drainage device. It is used to detect whether the water level in the inner pipe 21 has reached the second position and accordingly control the opening and closing of the drainage device, thus achieving automatic start and stop of the drainage device. Specifically, the drainage device is configured to start drainage when the water level in the inner pipe 21 is higher than or equal to the preset second position; and to shut off drainage when the water level in the inner pipe 21 is lower than the preset second position, to prevent excessive reduction in the soil water level.

[0036] In this embodiment, the drainage device includes a siphon pipe 41 and a solenoid valve 42 mounted on the siphon pipe 41. One end of the siphon pipe 41 is submerged in the water of the inner pipe 21, and the other end extends outside the drainage pile, with the outlet height lower than a preset second position to maintain siphon drainage. A level sensor 52 is connected to the controller of the solenoid valve 42. When the water level in the inner pipe 21 is higher than or equal to the second position, the controller controls the solenoid valve 42 to open, allowing the water in the inner pipe 21 to drain to the outside of the pile via the siphon pipe 41 using the siphon principle. When the water level in the inner pipe 21 is lower than the second position, the controller controls the solenoid valve 42 to close, stopping drainage and preventing environmental risks such as uneven foundation settlement caused by excessive rainfall. In other embodiments, the drainage device can also use equipment such as a water pump for active drainage.

[0037] In this embodiment, the second position is lower than the first position. When the water level in the inner pipe 21 is low and above the second position but not reaching the first position, the drainage device discharges the water in the inner pipe 21 at a second rate. At this time, the crushed stone pile 1 relies on natural seepage to complete the drainage of the surrounding soil layer. When the water level in the inner pipe 21 continues to rise and reaches the first position, the negative pressure generating device is activated, forming a negative pressure in the water collection chamber 23 to accelerate the convergence of excess pore water in the surrounding soil layer to the water collection chamber 23. At the same time, the drainage device drains water at a first rate, which is greater than the second rate, and can quickly reduce the water content of the soil layer around the drainage pile, thereby achieving rapid response and control of the liquefaction process.

[0038] like Figure 3 As shown, in this embodiment, a drainage method is also disclosed, employing the aforementioned drainage piles for deep liquefiable soil layers, comprising the following steps: S1. Monitor the water level in the inner pipe 21. When the water level in the inner pipe 21 is higher than the second position, start the drainage device to discharge the water in the inner pipe 21 to the outside.

[0039] Specifically, when the water level in the inner pipe 21 is higher than the second position, the liquid level sensor 52 in the water level monitoring device sends a signal, the controller controls the solenoid valve 42 of the drainage device to open, the drainage device starts, and the water in the inner pipe 21 is discharged outward through the siphon pipe 41 at the second rate.

[0040] S2. Continuously monitor the water level in the inner pipe 21. When the water level in the inner pipe 21 continues to rise above the first position, activate the negative pressure generating device to generate a negative pressure environment in the water collection chamber 23, accelerating the water around the drainage pile to gather in the water collection chamber 23.

[0041] Specifically, when the water level in the inner pipe 21 continues to rise above the first position, the float 51 in the water level monitoring device moves upward, causing the gate 34 to close. The negative pressure generating device starts, and the vacuum pump 32 generates a negative pressure environment in the water collection chamber 23 through the suction pipe 31, accelerating the collection of excess pore water in the liquefied soil around the drainage pile into the water collection chamber 23, and then flowing into the inner pipe 21 through the through hole 25 at the bottom of the inner pipe 21. At this time, the drainage rate of the drainage device increases to the first rate, and the second rate is less than the first rate to match the larger inflow volume, ensuring that the water level in the inner pipe 21 is effectively controlled.

[0042] S3. When the water level in the inner pipe 21 is equal to or lower than the second position, close the drainage device.

[0043] As drainage proceeds, the water level in the inner pipe 21 gradually decreases. When the water level is equal to or lower than the second position, the level sensor 52 sends a signal, the controller controls the solenoid valve 42 to close, and the drainage device stops draining to prevent excessive water loss. At the same time, the water level is also lower than the first position, the float ball 51 has moved down, the gate 34 is disconnected, and the negative pressure generating device stops working.

[0044] When liquefaction occurs in the soil surrounding the drainage piles and the excess pore water pressure rises sharply, this drainage method utilizes negative pressure to accelerate the collection of water in the soil. Working in conjunction with the drainage device, it can quickly drain the water, thereby rapidly dissipating the deep excess pore water pressure, restoring the effective stress of the foundation, and thus improving the liquefaction resistance and post-earthquake stability of the foundation soil. Under normal operating conditions, the drainage piles drain water naturally at a conventional rate, avoiding unnecessary energy consumption.

[0045] The drainage pile of the present invention improves the drainage efficiency and pore water pressure dissipation rate in deep liquefiable soil layers by constructing a composite water collection pipe 2 inside the crushed stone pile body 1, combined with an active negative pressure pumping and automatic water level monitoring mechanism, while avoiding the risk of excessive precipitation, and has broad engineering application prospects.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A drainage pile for deep liquefiable soil layers, characterized in that, include: The crushed stone piles are installed in the liquefiable soil layer; A composite water collection pipe is installed in the crushed stone pile body, including an inner pipe and an outer pipe provided on the outer periphery of the inner pipe. The side wall of the outer pipe is provided with several water passage holes. An annular water collection cavity is formed between the inner pipe and the outer pipe. The bottom of the inner pipe is provided with a through hole communicating with the water collection cavity. A negative pressure generating device is connected to the water collection chamber and is used to generate a negative pressure environment in the water collection chamber. A drainage device, one end of which extends into the inner pipe, is used to drain water from the inner pipe; A water level monitoring device is installed in the inner pipe and connected to the controller of the negative pressure generating device. When the water level in the inner pipe rises to the first position, the negative pressure generating device is triggered to start.

2. The drainage pile for deep liquefiable soil layers as described in claim 1, characterized in that, The composite water collection pipe is vertically installed at the center of the crushed stone pile.

3. The drainage pile for deep liquefiable soil layers as described in claim 1, characterized in that, A check valve is provided at the through hole, and the check valve controls the water flow from the water collection chamber to the inner pipe in one direction.

4. The drainage pile for deep liquefiable soil layers as described in claim 1, characterized in that, The negative pressure generating device includes a suction pipe, a vacuum pump, an AC contactor, and a switch. One end of the suction pipe is connected to the vacuum pump, and the other end is connected to the upper end of the water collection chamber.

5. The drainage pile for deep liquefiable soil layers as described in claim 4, characterized in that, The water level monitoring device includes a float that swings up and down at the first position. The upper end of the float is connected to the switch. When the float moves up, it closes the switch; when the float moves down, it opens the switch.

6. The drainage pile for deep liquefiable soil layers as described in claim 1, characterized in that, The water level monitoring device includes a liquid level sensor connected to the drainage device. The liquid level sensor is located at a second position in the inner pipe. The drainage device is configured to start drainage when the water level in the inner pipe reaches the second position.

7. The drainage pile for deep liquefiable soil layers as described in claim 6, characterized in that, The drainage device includes a siphon pipe and a solenoid valve installed on the siphon pipe. One end of the siphon pipe is placed in the water in the inner pipe, and the other end of the siphon pipe extends outside the drainage pile and is lower than the second position. The liquid level sensor is connected to the controller of the solenoid valve. When the water level in the inner tube is higher than the second position, the controller controls the solenoid valve to open. When the water level in the inner tube is lower than the second position, the controller controls the solenoid valve to close.

8. The drainage pile for deep liquefiable soil layers as described in claim 7, characterized in that, The second position is lower than the first position.

9. A drainage method employing drainage piles for deep liquefiable soil layers as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Monitor the water level in the inner pipe. When the water level in the inner pipe is higher than the second position, start the drainage device to discharge the water in the inner pipe to the outside. S2. When the water level in the inner pipe continues to rise and exceeds the first position, the negative pressure generating device is activated to generate a negative pressure environment in the water collection chamber, accelerating the water around the drainage pile to gather in the water collection chamber. S3. When the water level in the inner pipe is equal to or lower than the second position, close the drainage device.

10. The drainage method as described in claim 9, characterized in that, When the water level in the inner pipe is higher than the first position, the drainage rate of the drainage device is the first rate; when the water level in the inner pipe is higher than the second position but lower than the first position, the drainage rate of the drainage device is the second rate; the first rate is greater than the second rate.

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