Capillary drainage gravel pipe pile for collapsible aeolian sand foundation in Sagomean area and construction method

Abstract

The invention discloses a capillary drainage gravel pipe pile for a collapsible aeolian sand foundation in a Sagomei district and a construction method, the capillary drainage gravel pipe pile comprises a porous pipe pile buried in sandy soil, micropores are uniformly formed in the porous pipe pile, gravel is filled outside the porous pipe pile to form a hollow gravel pile, and the hollow gravel pile is filled with water. A capillary drainage permeable pipe is arranged in the porous pipe pile; the construction method comprises the following steps that a construction area is cleaned, the vibroflot is hoisted through a crane to sink into a soil layer, then the outer-layer steel sleeve is installed outside the vibroflot and sinks into a preset depth together with the vibroflot, the porous pipe pile is installed inside the outer-layer steel sleeve, the space between the porous pipe pile and the outer-layer steel sleeve is filled with gravel, and a hollow gravel pile is formed; and meanwhile, the vibroflot is lifted, then water is injected and pumped into the porous pipe pile, the foundation is pre-settled, and finally the capillary drainage permeable pipe is installed in the porous pipe pile. The method can reduce the later settlement of the foundation, improve the construction quality, improve the bearing capacity of the foundation and enhance the anti-seismic property of the foundation.

Description

Technical Field

[0001] The present invention relates to the field of wind and photovoltaic energy transmission technology, and in particular to a capillary drainage gravel pipe pile and a construction method for collapsible aeolian sand foundation in Shagohuang area. Background Art

[0002] Deserts, Gobi and wasteland areas are rich in solar and wind energy resources and are hot spots for new energy development. However, the foundations in desert areas often suffer from collapsible settlement problems due to loose soil, low water content and uneven soil quality.

[0003] In the construction of projects in the Shagohuang area, existing foundation reinforcement technologies are currently widely used, such as tamping, geotextile laying, gravel piles, concrete piles, etc. In addition, patent document CN117005333A proposes a sandstorm protection system and protection method for Shagohuang area, which can effectively reduce the sand burial and wind erosion hazards encountered in photovoltaic construction in Shagohuang area, and provide technical guarantee for the safe operation of photovoltaic power fields in such areas; in addition, patent document CN222206318U proposes a composite bearing structure with grouting around prefabricated pipe piles, which is suitable for the lower structure with prefabricated pipe piles as assembled structures.

[0004] The above-mentioned existing technologies can improve foundation performance to a certain extent, but the effects are limited in long-term settlement control and moisture regulation. In addition, traditional drainage equipment is difficult to adapt to the dynamic moisture content changes in the desert. Therefore, for the collapsible aeolian sand foundation in the Shagohuang area, an innovative solution that comprehensively considers foundation reinforcement and drainage performance improvement is urgently needed. Summary of the invention

[0005] The object of the present invention is to provide a capillary drainage gravel pipe pile and a construction method for collapsible aeolian sand foundation in Shagohuang area, so as to solve the problems and defects mentioned in the above background technology.

[0006] In order to achieve the above purpose, the following technical solutions are provided:

[0007] A capillary drainage gravel pipe pile for collapsible aeolian sand foundation in Shagohuang area comprises a porous pipe pile buried in sand, the porous pipe pile is evenly provided with micropores, the porous pipe pile is filled with gravel outside to form a hollow gravel pile, and a capillary drainage permeable pipe is arranged inside the porous pipe pile.

[0008] Preferably, the porosity of the porous pipe pile is not less than 20%, and the compressive strength is not less than 30 MPa, so as to ensure the formation of a smooth drainage channel and increase the overall stability of the pile structure.

[0009] Preferably, the matrix suction of the capillary drainage pipe is not less than 100 kPa, and the compressive strength is not less than 1 MPa, so as to ensure the stability of the foundation in an unsaturated state.

[0010] Preferably, the crushed stone has a mud content of no more than 5%, a maximum particle size of no more than 4 cm, and a crushed stone density of no less than 2.5 g / cm 3 , the particle hardness is not less than 50Mpa to ensure the density and uniformity of the crushed stone.

[0011] A capillary drainage gravel pipe pile construction method for collapsible aeolian sand foundation in Shagohuang area comprises the following steps:

[0012] Step S1: Preparation before construction, including comprehensive cleaning of loose sand and soil on the surface of the construction area to ensure that the foundation construction surface is flat and free of debris, and then accurately locate the center of the pile according to the construction drawings, use a crane to lift the vibrator and align it with the center of the pile, start the submersible motor to drive the eccentric block to generate high-frequency vibration, and at the same time start the water pump to spray high-pressure water through the nozzle, so that the vibrator sinks into the soil layer under the action of vibration and impact, and the sinking depth shall not be less than 1 meter;

[0013] Step S2: After the vibrator is sunk into the soil layer, an outer steel casing is installed outside the vibrator, and the vibrator is started again to make the vibrator and the outer steel casing sink together, and the vibrator is lifted after sinking to a predetermined depth;

[0014] Step S3: installing a porous pipe pile inside the outer steel casing, wherein the porous pipe pile is evenly provided with pores, the porous pipe pile is sunk to the same depth as the outer steel casing, and is aligned with the central axis of the outer steel casing;

[0015] Step S4: gravel is filled between the outer steel casing and the porous pipe pile. After the gravel is filled, a hollow impact hammer is installed and its vibration function is activated to perform multi-stage impact compaction on the gravel material, while the outer steel casing is slowly lifted, so as to finally form a hollow gravel pile;

[0016] Step S5: injecting water into the porous pipe pile to make the deep part of the foundation immersed in water for pre-settlement, wherein the water injection depth is not greater than 80% of the designed pile length, and the water injection rate is controlled within 500L / min. After the water injection is completed, the water in the porous pipe pile is pumped out by a vacuum pump, and the saturated water state is retained for no less than 24 hours after the pumping to ensure stable settlement;

[0017] Step S6: After ensuring that the settlement is stable, a capillary drainage pipe is installed in the porous pipe pile.

[0018] Preferably, in step 2, when the vibrator and the outer steel casing are sinking together, the sinking action needs to be paused and the vibration needs to be maintained for 30 seconds every time the sinking depth reaches 1m. The sinking speed must not exceed 3m / min, and during the sinking process, the verticality of the pile needs to be continuously checked to ensure that the verticality deviation of the outer steel casing is not greater than 1 / 100.

[0019] Preferably, in step 4, the impact energy of the hollow impact hammer is not less than 2 kJ, and the vibration frequency is not less than 30 Hz.

[0020] Preferably, when lifting the outer steel casing, the hollow impact hammer needs to maintain continuous vibration for no less than 1 minute, and the lifting speed of the outer steel casing is controlled within the range of 1.2 to 1.5 m / min to prevent loosening of the pile structure or uneven stress due to excessively rapid pulling out of the pipe.

[0021] Preferably, in step 5, the water injection rate is controlled within 500 L / min, and the water pumping rate is controlled within 300 L / min. The water injection and pumping rates are strictly controlled to ensure that the foundation can reach a saturated water state, which is beneficial to subsequent pre-settlement.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) In the present invention, during the foundation construction process, the structural design of the porous pipe piles and the operations of water injection and pumping are used to achieve simultaneous pre-settlement of the shallow and deep parts of the foundation, significantly reducing the later settlement and improving the construction quality;

[0024] (2) In the present invention, by replacing capillary drainage pipes with different suction forces according to soils with different moisture contents, the matrix suction and moisture content of different soils can be effectively controlled, thereby improving the bearing capacity of the foundation;

[0025] (3) In the present invention, a good drainage channel is formed inside the pile, which can significantly reduce the excess pore water pressure that may occur during an earthquake and enhance the seismic resistance of the foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall longitudinal section structure of a capillary drainage gravel pipe pile used for collapsible aeolian sand foundation in Shagohuang area of ​​the present invention;

[0027] Figure 2 It is a schematic diagram of the overall transverse cross-sectional structure of a capillary drainage gravel pipe pile used for a collapsible aeolian sand foundation in a Shagohuang area according to the present invention;

[0028] Figure 3 This is a schematic diagram of the outer steel casing structure of a capillary drainage gravel pipe pile used for collapsible aeolian sand foundation in Shagohuang area of ​​the present invention;

[0029] Figure 4 It is a schematic diagram of a porous pipe pile structure of a capillary drainage gravel pipe pile used for collapsible aeolian sand foundation in Shagohuang area of ​​the present invention;

[0030] Figure 5 It is a schematic diagram of the structure of a capillary drainage permeable pipe of a capillary drainage gravel pipe pile used for a collapsible aeolian sand foundation in a Shagohuang area according to the present invention;

[0031] Figure 6 It is a schematic diagram of the construction method of capillary drainage gravel pipe piles for collapsible aeolian sand foundation in Shagohuang area according to the present invention;

[0032] Figure numerals: 1. vibrator; 2. outer steel casing; 3. porous pipe pile; 31. micropore; 4. hollow impact hammer; 5. hollow gravel pile; 6. capillary drainage head pipe; 7. sand. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings, and several embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0035] like Figures 1 to 5 As shown, a capillary drainage gravel pipe pile for collapsible aeolian sand foundation in Shagohuang area includes a porous pipe pile 3 buried in sand 7, micropores 31 are evenly arranged on the porous pipe pile 3, the outside of the porous pipe pile 3 is filled with gravel to form a hollow gravel pile 5, and a capillary drainage permeable pipe 6 is arranged inside the porous pipe pile 3.

[0036] The porosity of the porous pipe pile 3 is not less than 20%, and the compressive strength is not less than 30 MPa, so as to ensure the formation of a smooth drainage channel and increase the overall stability of the pile structure.

[0037] The matrix suction of the capillary drainage pipe 6 is not less than 100 kPa, and the compressive strength is not less than 1 MPa, so as to ensure the stability of the foundation in an unsaturated state.

[0038] The mud content of the crushed stone shall not exceed 5%, the maximum particle size shall not exceed 4cm, and the density of the crushed stone shall not be less than 2.5g / cm 3, the particle hardness is not less than 50Mpa to ensure the density and uniformity of the crushed stone.

[0039] like Figure 6 As shown, a construction method of capillary drainage gravel pipe piles for collapsible aeolian sand foundation in Shagohuang area specifically comprises the following steps:

[0040] Step S1: Before the construction begins, the surface loose sand 7 of the construction area is thoroughly cleaned to ensure that the foundation construction surface is flat and free of debris. The center position of the pile is accurately located according to the design drawings, and the pile position deviation is required to be no more than 60mm. For the pile layout requirements of different foundation forms, the following deviation limits must be strictly followed: the pile position deviation of the full-floor pile foundation shall not exceed 0.4 times the pile diameter; the pile position deviation of the strip foundation shall not exceed 0.25 times the pile diameter; the pile position deviation of the single-row pile shall not exceed 60mm. After the positioning is completed, the vibrator 1 is lifted by a crane, and the submersible motor is started to drive the eccentric block to generate high-frequency vibration. At the same time, the water pump is turned on, and the vibrator 1 is gradually sunk into the soil layer under the combined action of vibration and water flow impact through high-pressure water jets, and the minimum sinking depth shall not be less than 1m. Among them, the vibration frequency of the vibrator 1 is required to be no less than 50Hz, and the eccentric force is no less than 30kN.

[0041] Step S2: Install the outer steel casing 2 on the outside of the vibrator 1, start the vibrator 1 again, and sink the vibrator 1 and the outer steel casing 2 to a predetermined depth through the combined effect of high-frequency vibration and high-pressure water jet. During the sinking process, the sinking action needs to be paused and the vibration needs to be maintained for 30 seconds for every 1m of sinking depth to further compact the surrounding soil layer. The sinking speed needs to be strictly controlled to not exceed 3m / min to avoid deviations during the construction process. During the entire sinking process, the verticality of the pile needs to be continuously tested to ensure that the verticality deviation of the outer steel casing 2 is not greater than 1 / 100. Among them, the outer steel casing 2 requires a wall thickness of not less than 10mm and a diameter tolerance of not more than ±2mm.

[0042] Step S3: Install the porous pipe pile 3 inside the outer steel casing 2. The porous pipe pile 3 is a prefabricated pipe pile. During installation, it is necessary to ensure that the porous pipe pile 3 is accurately sunk to a predetermined depth and aligned with the central axis of the outer steel casing 2. The pore design of the porous pipe pile 3 is intended to ensure the subsequent formation of a smooth drainage channel and increase the overall stability of the pile structure. The porous pipe pile 3 is required to have a porosity of not less than 20% and a compressive strength of not less than 30 MPa.

[0043] Step S4: Fill the area between the outer steel casing 2 and the porous pipe pile 3 with crushed stones. The filling material must meet the following quality requirements: the mud content shall not exceed 5%, the maximum particle size shall not exceed 4 cm, and the crushed stone density shall not be less than 2.5 g / cm 3, the particle hardness is not less than 50MPa. After the filling is completed, the hollow impact hammer 4 is installed, and its vibration function is started to perform multi-stage compaction on the crushed stone material. The impact energy of the hollow impact hammer 4 is required to be not less than 2kJ, and the vibration frequency is not less than 30Hz. When lifting the outer steel casing 2, the hollow impact hammer 4 needs to maintain continuous vibration for not less than 1min to ensure the density and uniformity of the crushed stone. During the lifting of the outer steel casing 2, the lifting speed should be strictly controlled within the range of 1.2 to 1.5m / min to prevent the loosening of the pile structure or uneven stress due to excessively fast pulling out of the pipe. Finally, the hollow gravel pile 5 is formed, and the actual porosity of the hollow gravel pile 5 must reach or exceed 1.1 times the designed minimum porosity ratio, so as to meet the dual requirements of bearing capacity and drainage performance.

[0044] Step S5: After the pile construction is completed, first, water is injected into the porous pipe pile 3 to allow the deep part of the foundation to be immersed in water for pre-settlement. During the water injection process, it is necessary to ensure that the water injection depth is no more than 80% of the designed pile length, and the water injection rate is controlled within 500L / min; then, the hole is pumped, and the pumping rate is controlled within 300L / min. After the pumping is completed, the saturated water state is retained for no less than 24 hours to ensure stable settlement.

[0045] Step S6: After waiting for the settlement to stabilize, install the capillary drainage pipe 6 inside the porous pipe pile 3. The capillary drainage pipe 6 absorbs and removes the moisture in the sand through capillary action, forming a stable reverse drainage system, thereby significantly reducing the soil moisture content and enhancing the overall stability of the pile foundation. The capillary drainage pipe 6 must meet the following performance indicators: the matrix suction is not less than 100kPa, and the capillary drainage pipe 6 with different matrix suction is replaced according to different soils to control the matrix suction and moisture content; the compressive strength is not less than 1MPa to ensure the stability of the foundation in an unsaturated state.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A capillary drainage gravel pipe pile for collapsible aeolian sand foundation in Shagohuang area, characterized in that: The invention comprises a porous pipe pile (3) buried in sand (7), micropores (31) are evenly arranged on the porous pipe pile (3), gravel is filled outside the porous pipe pile (3) to form a hollow gravel pile (5), and a capillary drainage pipe (6) is arranged inside the porous pipe pile (3).

2. A capillary drainage gravel pipe pile for collapsible aeolian sand foundation in Shagohuang area, characterized in that: The porosity of the porous pipe pile (3) is not less than 20%, and its compressive strength is not less than 30 MPa.

3. A capillary drainage gravel pipe pile for collapsible aeolian sand foundation in Shagohuang area, characterized in that: The matrix suction of the capillary drainage pipe (6) is not less than 100 kPa, and the compressive strength is not less than 1 MPa.

4. A capillary drainage gravel pipe pile for collapsible aeolian sand foundation in Shagohuang area, characterized in that: The mud content of the hollow gravel pile (5) shall not exceed 5%, the maximum particle size shall not exceed 4 cm, and the density of the gravel shall not be less than 2.5 g / cm 3 , particle hardness is not less than 50MPa.

5. A construction method for capillary drainage gravel pipe piles for collapsible aeolian sand foundation in Shagohuang area, characterized in that: The following steps are involved: Step S1: Pre-construction preparation, including comprehensive cleaning of the loose sand and soil on the surface of the construction area to ensure that the foundation construction surface is flat and free of debris, and then accurately locate the center position of the pile according to the construction drawings, use a crane to lift the vibrator (1) and align it with the center position of the pile, start the submersible motor to drive the eccentric block to generate high-frequency vibration, and at the same time start the water pump to spray high-pressure water through the nozzle, so that the vibrator (1) sinks into the soil layer under the action of vibration and impact, and the sinking depth shall not be less than 1 meter; Step S2: After the vibrator (1) sinks into the soil layer, an outer steel casing (2) is installed outside the vibrator (1), and the vibrator (1) is started again, so that the vibrator (1) and the outer steel casing (2) sink together, and the vibrator (1) is lifted after sinking to a predetermined depth; Step S3: installing a porous pipe pile (3) inside the outer steel casing (2), wherein the porous pipe pile (3) is evenly provided with pores, and the porous pipe pile (3) is sunk to the same depth as the outer steel casing (2) and aligned with the central axis of the outer steel casing (2); Step S4: gravel is filled between the outer steel casing (2) and the porous pipe pile (3). After the gravel is filled, a hollow impact hammer (4) is installed and its vibration function is activated to perform multi-stage impact compaction on the gravel material, while the outer steel casing (2) is slowly lifted, and finally a hollow gravel pile (5) is formed; Step S5: injecting water into the porous pipe pile (3) to make the deep part of the foundation undergo water immersion pre-settlement, wherein the water injection depth is not greater than 80% of the designed pile length, and the water injection rate is controlled within 500L / min. After the water injection is completed, the water in the porous pipe pile is pumped out using a vacuum pump, and the saturated water state is retained for no less than 24 hours after the pumping to ensure stable settlement; Step S6: After ensuring that the settlement is stable, a capillary drainage pipe (6) is installed in the porous pipe pile (3).

6. The construction method of capillary drainage gravel pipe piles for collapsible aeolian sand foundation in Shagohuang area according to claim 5 is characterized in that: In the second step, when the vibrator (1) and the outer steel casing (2) are sinking together, the sinking action needs to be paused and the vibration needs to be maintained for 30 seconds every time the sinking depth reaches 1m. The sinking speed must not exceed 3m / min. During the sinking process, the verticality of the pile needs to be continuously checked to ensure that the verticality deviation of the outer steel casing (2) is not greater than 1 / 100.

7. The construction method of capillary drainage gravel pipe piles for collapsible aeolian sand foundation in Shagohuang area according to claim 6 is characterized in that: In the step 4, the impact energy of the hollow impact hammer (4) is not less than 2 kJ, and the vibration frequency is not less than 30 Hz.

8. The construction method of capillary drainage gravel pipe piles for collapsible aeolian sand foundation in Shagohuang area according to claim 7, characterized in that: When lifting the outer steel casing (2), the hollow impact hammer (4) needs to maintain continuous vibration for no less than 1 minute, and the lifting speed of the outer steel casing (2) is controlled within the range of 1.2 to 1.5 m / min.

9. The construction method of capillary drainage gravel pipe piles for collapsible aeolian sand foundation in Shagohuang area according to claim 5, characterized in that: In step 5, the water injection rate is controlled within 500 L / min, and the water extraction rate is controlled within 300 L / min.

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