Long spiral secant pile construction method for water conservancy anti-seepage complex geological conditions

Abstract

The invention relates to the technical field of pile foundation construction, in particular to a long spiral secant pile construction method under water conservancy anti-seepage complex geological conditions, and the construction method comprises the steps that a long spiral pile driver is provided with a first power head and a second power head, a sleeve is pressed downwards through the second power head, and then the first power head is used for driving a drill rod to drill; the sleeve and the drill rod drill down synchronously until the drill bit drills to the elevation of the bed rock surface to form a pile hole; the sleeve is left in the pile hole, the rotary drilling rig is used for drilling the bed rock, a drill rod of the long spiral pile driver is put down to the bottom of the pile hole, concrete is pumped into the pile hole, and when the concrete is poured to the bed rock surface, the drill rod and the sleeve are lifted while the concrete is pumped into the pile hole till pressure pouring is completed. In a complex stratum with a huge thick loose high-permeability sandy gravel covering layer and ultrahigh-strength hard bed rock coexisting, high-precision stable hole forming and collapse prevention are achieved at the same time, hard rock is reliably and accurately drilled to reach the designed depth, and it is ensured that concrete secant piles are tightly engaged to form a continuous and effective diaphragm wall.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of pile foundation construction, in particular to a long spiral interlocking pile construction method for water conservancy seepage prevention under complex geological conditions. BACKGROUND

[0002] In the construction of cutoff walls in the fields of water conservancy and hydropower, deep foundation pit support, etc., a kind of extremely challenging complex stratum structure is often encountered. Its typical characteristics are as follows: the upper cover layer is a deep (often tens of meters) loose, large particle size, high permeability sand and gravel layer. Such stratum structure is extremely unstable, with large pores, and is prone to hole collapse, slurry leakage and even drill burying, which poses a great threat to the hole wall stability and verticality control during the hole forming process. The lower part is directly a high-strength hard rock (such as granite, diabase, quartzite, etc.) with a saturated uniaxial compressive strength standard value far exceeding 20 MPa (often up to 40 MPa or more). The design of the cutoff wall requires that the pile body must be reliably embedded in this hard rock layer to the specified depth to form an effective end water-blocking barrier. This "extremely unstable upper part and extremely hard lower part" geological combination poses almost contradictory dual requirements for the construction technology: strong wall protection measures are needed to maintain the stability of the hole type in the upper part, and strong rock breaking capacity is needed to achieve accurate rock penetration in the lower part.

[0003] For the complex stratum with both thick, high-permeability sand and gravel cover layer and super-high-strength bedrock, the existing cutoff wall construction technology cannot meet the requirements of hole stability and verticality during rock penetration: the technology that can effectively maintain the stability and verticality of the deep hole in the upper sand and gravel layer (usually relying on strong physical wall protection) is severely restricted or even completely unable to implement effective drilling in the lower hard rock, which cannot meet the requirement of rock penetration depth. On the contrary, the technology that can effectively drill into the hard rock cannot reliably form and maintain a deep hole for hard rock drilling in the upper part of such loose and unstable stratum. SUMMARY

[0004] In order to simultaneously achieve high-precision stable hole forming without collapse, reliable and accurate rock drilling to the designed depth in the complex stratum with both thick, loose, high-permeability sand and gravel cover layer and super-high-strength hard bedrock, and ensure the tight interlocking of the concrete interlocking piles to form a continuous and effective cutoff wall, the application provides a long spiral interlocking pile construction method for water conservancy seepage prevention under complex geological conditions.

[0005] The long spiral interlocking pile construction method for water conservancy seepage prevention under complex geological conditions provided by the application adopts the following technical solution: A long spiral interlocking pile construction method for water conservancy seepage prevention under complex geological conditions, comprising the following steps: Constructing a guide wall at the target pile position to locate the hole position; The long spiral pile driver is provided, which is configured as double power, has a first power head and a second power head, the first power head is connected with a drill rod for driving the drill rod to drill, the drill rod is connected with a drill bit, and the second power head is detachably connected with a sleeve arranged outside the drill rod for pressing the sleeve downward; The drill bit is aligned with the hole position, the sleeve is pressed downward to a preset depth by the second power head, and then the drill rod is driven to drill by the first power head, the sleeve and the drill rod are synchronously lowered, the bottom surface of the sleeve is always located below the drill bit, and the drill bit is drilled to the bedrock surface level to form a pile hole; After the drilling is completed, the drill rod is lifted, the second power head is separated from the sleeve, and the sleeve is left in the pile hole; The bedrock is drilled from the pile hole by a rotary drilling rig until the target depth of the bedrock is reached; After the rotary drilling is completed, the rotary drilling rig is removed, the drill rod of the long spiral pile driver is lowered to the bottom of the pile hole, and the concrete is pumped into the pile hole by a concrete pump, when the concrete is pumped to the bedrock surface, the drill rod and the sleeve are lifted at the same time until the pressure filling is completed.

[0006] Optionally, the step of "constructing a guide wall at the target pile position to position the hole position" comprises the following steps: The guide wall trench is mechanically excavated at the target pile position; The guide wall reinforcement is arranged in the guide wall trench; The guide wall formwork is installed outside the guide wall reinforcement; The concrete is poured into the guide wall formwork, and after the concrete strength meets the requirements, the guide wall formwork is removed to form the guide wall positioning hole position.

[0007] Optionally, the concrete pumped into the pile hole is super slow setting concrete, and the initial setting time is 24-30h; and / or During the synchronous drilling of the sleeve and the drill rod, the bottom surface of the sleeve is always located below the drill bit, and the distance is 0.5-1m.

[0008] Optionally, the step of "pumping the concrete into the pile hole by the concrete pump, when the concrete is pumped to the bedrock surface, the drill rod and the sleeve are lifted at the same time until the pressure filling is completed" comprises the following steps: The concrete is pumped into the drill rod; After the drill rod is filled with concrete and reaches a preset pressure, the drill rod is started to be pulled up, and the pulling speed is matched with the concrete pumping speed; When the concrete is pumped to the bedrock surface, the drill rod and the sleeve are pulled up while the concrete is pumped, the drill rod and the sleeve are lifted while the concrete is being pressed, the bottom surface of the sleeve is always below the drill bit during the lifting process, and the distance is 0.5-1 m.

[0009] Optionally, the sleeve wall is provided with a grouting channel, the top of the sleeve is provided with a grouting port in communication with the grouting channel, the lower end of the sleeve is provided with a plurality of slurry outlets in communication with the grouting channel, the plurality of slurry outlets are arranged in a circumferential interval around the sleeve and are provided with one-way valves, and the slurry outlets are at the same height as the drill bit after the sleeve is lowered. When the concrete is pumped into the pile hole by using a concrete delivery pump, when the concrete is pumped to the bedrock surface, the drill rod and the sleeve are lifted while the concrete is pumped, and the thick mud slurry containing the accelerator is injected into the sleeve wall through the grouting port to make the thick mud slurry be injected outside the sleeve.

[0010] Optionally, when the sleeve is pressed down by using the second power head, the thin mud slurry containing the lubricant is injected into the sleeve wall through the grouting port to make the thin mud slurry be injected outside the sleeve.

[0011] Optionally, when the sleeve is pressed down to 1-2 m above the bedrock surface, the injection of the thin mud slurry is stopped, and the thick mud slurry is injected instead, the thick mud slurry is injected while the sleeve is pressed down, and the drill bit drills to the bedrock surface.

[0012] Optionally, the slurry outlets at the lower part of the sleeve are arranged obliquely downward, the slurry outlets at the middle part are arranged in a horizontal direction, and the slurry outlets at the upper part are arranged obliquely upward.

[0013] Optionally, the plurality of slurry outlets are distributed in a spiral line around the sleeve to form a spiral grouting track.

[0014] Optionally, after the pressing and pouring are completed, the operation is repeated to form a plurality of a type of pile bodies arranged in an interval, a rotary drilling rig is used to drill between adjacent a type of pile bodies before the a type of pile bodies are initially set, and a middle pile hole is formed by hard cutting the a type of pile bodies and the soil bodies. A second type of pile body is formed by pouring concrete into the middle pile hole, and the second type of pile body is formed between every adjacent two a type of pile bodies, so that each a type of pile body and each second type of pile body are arranged in one-to-one occlusion.

[0015] In summary, the present application includes at least one of the following beneficial technical effects: 1. The sleeve of the double power head long spiral pile driver forms immediate support for the upper loose and collapsible stratum, solving the problem of hole collapse and drill burying when using rotary drilling machine alone; at the same time, the strong rock-embedding capacity of the rotary drilling machine is used for drilling in high-strength hard rock, making up for the deficiency of insufficient cutting capacity of the long spiral pile driver in hard rock, realizing continuous and stable construction from the upper loose stratum to the lower hard rock, and meeting the requirements of the cutoff wall design on the depth of rock penetration.

[0016] 2. Through the cooperative operation of the double power head long spiral pile driver and the rotary drilling machine, the problems of high construction difficulty and low efficiency caused by the use of rotary drilling machine alone are avoided, and the limitations of the use of long spiral pile driver alone are also reduced; at the same time, the occurrence of accidents such as hole collapse and drill burying is reduced, the equipment wear and tear and rework cost are reduced, the construction progress is improved as a whole, and the unity of economic benefit and safety benefit is realized under the premise of ensuring construction quality.

[0017] 3. The guide wall provides a precise positioning reference for the hole site, and the verticality of the drill pipe and the sleeve is controlled cooperatively by the double power head, effectively reducing the hole site deviation and the verticality deviation of the pile body; the continuous supporting effect of the sleeve during the hole forming and concrete pouring process avoids accidents such as hole collapse and pile breakage, ensures the tight engagement of the pile body, reduces the leakage risk caused by poor engagement, and lays a foundation for forming a continuous and complete anti-seepage structure. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a flowchart of the long spiral engagement pile construction method in the water conservancy anti-seepage complex geological conditions in embodiment 1 of the present application; Figure 2 is a structural diagram of the synchronous down pressure drilling of the sleeve and the drill pipe in embodiment 1 of the present application; Figure 3 is a structural diagram of the drill bit drilling to the bedrock surface in embodiment 1 of the present application; Figure 4 is a structural diagram of the synchronous upward movement of the sleeve and the drill pipe in embodiment 2 of the present application; Figure 5 is Figure 4 is a partial enlarged diagram of position A in Figure 6 is a structural diagram of the synchronous down pressure drilling of the sleeve and the drill pipe in embodiment 3 of the present application; Figure 7 is Figure 6 is a partial enlarged diagram of position B in

[0019] MARKING OF THE DRAWINGS: 1. Drill pipe; 2. Drill bit; 3. Sleeve; 31. Grouting channel; 32. Grouting port; 33. Slurry outlet. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings Figures 1-7 The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings

[0021] With reference to Figure 1 The embodiments of the present application disclose a construction method of long spiral interlocking pile under complex geological conditions for water conservancy seepage prevention, comprising the following steps: A guide wall is constructed at the target pile position to position the hole position of the first type of pile body and ensure the stability of subsequent hole forming construction, specifically comprising the following steps: The guide wall trench is mechanically excavated at the target pile position. The site of the first type of pile body construction area is leveled, and surface debris, obstacles and floating soil are removed to ensure the flatness of the construction surface. The axis of the guide wall is accurately positioned according to the design pile position coordinates, and the axis control pile and the elevation control point are arranged along the axis direction. According to the diameter of the first type of pile body, the overlap width and the design requirements of the guide wall structure, the excavation range of the guide wall trench (including width, length and depth) is calculated and determined, and the trench boundary is marked on the ground with lime line. The guide wall trench is excavated along the marked lime line by using a hydraulic excavator.

[0022] The guide wall reinforcement is arranged in the guide wall trench, and the guide wall formwork is installed outside the guide wall reinforcement. The guide wall formwork adopts a combined steel formwork, the formwork height is consistent with the design height of the guide wall, the formwork splicing part is connected by bolts, and sponge strips are pasted at the joint part to prevent slurry leakage. The formwork needs to be cleaned, rusted and brushed with release agent before installation. The outside of the formwork adopts a steel pipe scaffold as a support system to ensure that the formwork does not deform and displace during concrete pouring.

[0023] The guide wall formwork is poured with concrete, and after the concrete strength meets the requirements, the guide wall formwork is removed to form the guide wall to position the hole position.

[0024] The guide wall is formed by pouring concrete into the template and removing the template after the strength of the concrete meets the requirements. This method can accurately position the hole and strictly control the verticality deviation of the subsequent first-type pile body, effectively constrain the deformation of the upper loose and collapsible stratum, prevent accidents such as hole collapse and drill burying during the hole forming process, provide a stable operation reference for long spiral piling machines and other equipment, reduce the problem of poor pile engagement caused by hole deviation, and thus provide protection for the accuracy and safety of subsequent first-type pile construction and lay a foundation for forming a continuous and complete anti-seepage structure.

[0025] The long spiral piling machine is available from Wenzhou Zhenzhong Foundation Engineering Machinery Technology Co., Ltd. To adapt to the construction requirements of complex strata, the long spiral piling machine is configured with double power, has a first power head and a second power head, and the double power heads are cooperatively driven.

[0026] The first power head is fixedly connected with the upper end of the drill rod 1 through a high-strength coupling, the drill rod 1 is connected with a drill bit 2, is provided with a high-power hydraulic motor (with a rated power not less than 110 kW) and a reduction box, can output an adjustable rotating speed of 0-9.44 r / min and a torque of 40 T·m, and can drive the drill rod 1 to drive the drill bit 2 to realize cutting and mixing operations on the soil layer. The rod body of the drill rod 1 has a diameter of 300-600 mm, the outer wall is welded with continuous spiral blades, and the edges of the blades are inlaid with wear-resistant alloy strips, so that the overall rigidity of the drill rod 1 can be ensured to resist the drilling reaction force, and the cuttings can be upwardly conveyed through the spiral blades; the drill bit 2 is a pick drill, which can drill into soft rock with a saturated uniaxial compressive strength standard value of 15 MPa-20 MPa. The second power head is independently installed on the machine body guide frame, is connected with the top of a sleeve 3 sleeved on the outside of the drill rod 1 through a detachable connecting mechanism, is provided with a double-hydraulic-cylinder driving system, can provide an auxiliary rotating speed of 0-9.34 r / min and an axial downward pressure, is used for driving the sleeve 3 to follow synchronously, the sleeve 3 can cut into the stratum under the downward pressure of the second power head to form instant support for the hole wall. The detachable connecting mechanism can be quickly locked and released to complete the connection or separation of the second power head and the sleeve 3, and meet the operation requirements of leaving and recycling the sleeve 3 during construction. The double power heads are respectively provided with independent hydraulic control systems and sensors, the rotating speed, torque and downward pressure can be real-time adjusted and monitored through an operation table, the cooperative action accuracy of the drill rod 1 and the sleeve 3 during drilling is ensured, and equipment foundation is provided for the stability and verticality control of hole forming in complex strata. This is prior art and will not be described in detail.

[0027] The long spiral pile driver is moved to the guide groove, the drill bit 2 is aligned with the hole position, the drill rod 1 is slowly lowered until the steel wire rope of the first power head is no longer stressed, the drill bit 2 is inserted into the ground, and the verticality of the pile driver mainframe is adjusted to meet the requirements. The sleeve 3 is pressed down to a preset depth by the second power head, and the preset depth is determined according to the thickness of the upper loose stratum, and is usually 0.5-1 m into the upper loose stratum.

[0028] The drill rod 1 is driven to drill by the first power head, and the sleeve 3 is lowered into the hole synchronously with the drill rod 1, and the bottom surface of the sleeve 3 is always located below the drill bit 2 until the drill bit 2 drills into the surface of the lower hard bedrock to form a pile hole. Referring to Figure 2 and Figure 3 , Figure 2 is a structural schematic view of synchronous pressing drilling of the sleeve 3 and the drill rod 1 in the embodiment 1 of the present application, Figure 3 is a structural schematic view of drilling of the drill bit 2 to the bedrock surface in the embodiment 1 of the present application, wherein the dashed line in the drawing is the contact surface of the loose stratum and the hard bedrock, that is, the surface of the hard bedrock.

[0029] The first power head outputs the drilling torque to drive the drill bit 2 to cut the stratum, and the spiral blade transports the muck along the drill rod 1 upwards and discharges it outside the hole; the second power head synchronously provides the axial pressing force and the auxiliary rotating force to drive the sleeve 3 to follow the drilling, and instant support is formed through the close contact between the inner wall of the sleeve 3 and the hole wall.

[0030] In the process of synchronous drilling of the sleeve 3 and the drill rod 1, the bottom surface of the sleeve 3 is always located below the drill bit 2, and the distance is 0.5-1 m. The distance is set to be able to utilize the sleeve 3 to constrain the upper loose stratum in advance, prevent the hole wall from collapsing after the drill bit 2 cuts, and also reserve enough cutting operation space for the drill bit 2 to avoid interference between the sleeve 3 and the drill bit 2.

[0031] After the drilling is completed, the first power head lifts the drill rod 1, the second power head is disconnected from the sleeve 3, the sleeve 3 is left in the pile hole relying on its own gravity and the friction force with the hole wall, the sleeve 3 continues to support the upper loose stratum to prevent the pile hole from collapsing.

[0032] Subsequently, the rotary drilling rig is moved to the hole position, a matching drill bit 2 is selected according to the bedrock properties, the drill bit 2 of the rotary drilling rig is slowly lowered to the hard bedrock at the bottom of the pile hole through the inner hole of the sleeve 3, the rotary drilling rig is used to drill into the bedrock from the pile hole, the bedrock is broken through the impact extrusion and cutting action of the drill bit 2, until the target depth of the bedrock is drilled, at which time the drilling is stopped, and a complete hole body is formed, which is supported by the sleeve 3 in the upper part and embedded in the bedrock in the lower part.

[0033] After the rotary drilling is completed, the rotary drilling rig is first moved to a safe operation distance, and the site around the pile hole is cleaned to ensure the space for positioning the long spiral pile driver. The long spiral pile driver is operated to reposition, and the drill rod 1 is slowly lowered to the bottom of the pile hole. During the lowering process, the drill rod 1 is prevented from colliding with the inner wall of the sleeve 3 until the drill bit 2 touches the bottom rock surface of the hole. At this time, the top end of the drill rod 1 is connected to the inlet of the concrete delivery pump through a high-pressure hose. Pumping concrete into the drill rod 1 can form a closed delivery channel through the drill rod 1, avoiding the direct contact of the concrete with loose rock-soil during the delivery of the concrete in the complex stratum hole, thereby preventing segregation and bleeding of the concrete, and ensuring the workability and strength uniformity of the concrete.

[0034] The concrete is pumped into the pile hole by using a concrete delivery pump. The concrete is super-retarded concrete. By mixing with a high-efficiency retarding agent, the initial setting time is 24-30 h. The concrete is injected into the bottom of the hole through the discharge port at the bottom of the drill rod 1. After the drill rod 1 is completely filled with concrete and the pump pressure reaches the preset value, the first power head is started to pull up the drill rod 1 at a constant speed. The pulling-up speed of the drill rod 1 is strictly matched with the concrete pumping speed. The concrete can be fully filled in the bottom space of the hole and initially compacted through pressure, and the formation of negative pressure or cavities in the hole due to too fast pulling-up of the drill rod 1 can be avoided, thereby preventing defects such as pile breaking and necking, and ensuring the integrity of the pile body.

[0035] When the concrete is poured to the bedrock surface, the second power head of the long spiral pile driver is reconnected to the top of the sleeve 3, and then the synchronous lifting stage is entered. While continuously pumping concrete, the first power head and the second power head are coordinately controlled to simultaneously lift the drill rod 1 and the sleeve 3. During the lifting process, the bottom surface of the sleeve 3 is always located below the drill bit 2, and the distance between them is stably maintained at 0.5-1 m. On the one hand, the sleeve 3 can continue to support the upper part of the hole wall of the un-solidified concrete section, resist the lateral pressure of the loose stratum, and prevent the concrete from being squeezed out laterally or the hole wall from collapsing due to pressure imbalance. On the other hand, the distance setting can cause the drill bit 2 to moderately extrude the just-injected concrete during the lifting process, thereby further enhancing the compactness of the pile body. The drill rod 1 and the sleeve 3 are continuously lifted while the concrete is continuously pumped, until the pressure-pumping is completed. The delayed initial setting property of the super-retarded concrete can ensure that the concrete of the pile body remains plastic after the sleeve 3 is removed, thereby avoiding cracking caused by too fast early strength growth, reserving sufficient biting operation time for subsequent adjacent pile body construction, and finally ensuring the effective biting of the first-type pile body and the adjacent pile body, and improving the anti-seepage performance and mechanical stability of the overall structure.

[0036] After the pressure-pumping is completed, the operation is repeated to form a plurality of first-type pile bodies arranged in an interval. The first-type pile body is made of super-retarded concrete. Before the first-type pile body is initially set, the rotary drilling rig is used to drill between the adjacent first-type pile bodies to form a middle pile hole by hard cutting the adjacent first-type pile bodies and the soil. The concrete is poured into the middle pile hole to form a second type of pile body, and the concrete can be plain concrete, plastic concrete, reinforced concrete, etc. The second type of pile body is formed between each adjacent two first type of pile bodies, so that each first type of pile body and each second type of pile body are arranged in one-to-one corresponding engagement.

[0037] The continuous anti-seepage barrier is formed by the alternative engagement of the first type of pile body and the second type of pile body, which completely solves the problem of seepage in complex strata. The first type of pile body uses super-retarded concrete, which is hard cut by the second type of pile body before initial setting, so that the two types of concrete are directly embedded (the engagement surface has no joint). The super-retarded concrete used in the first type of pile body provides sufficient cutting window for the construction of the second type of pile body. The rotary drilling rig can accurately cut when the first type of pile body is still plastic, avoiding the problems of "cutting difficulty" and "pile body cracking" caused by the high strength of the first type of pile body in traditional engagement piles.

[0038] The sleeve 3 support and grouting technology for the construction of the first type of pile body has solved the problem of hole collapse in the upper loose stratum, and the construction of the second type of pile body can directly rely on the lateral restraint of the first type of pile body, without the need for repeated wall support, thereby improving the efficiency of single pile construction. At the same time, this method is suitable for complex geology such as sand and gravel layers and soft and hard alternating strata, and is especially suitable for engineering scenarios such as anti-seepage walls and foundation pit support.

[0039] This construction method can accurately position the hole and provide a stable reference for subsequent construction by constructing a guide wall at the target pile position, effectively controlling the verticality deviation of the pile body; the long spiral pile driver with double power heads cooperates the first power head to drive the drill rod 1 to drill and the second power head to press the sleeve 3 downward, so that the sleeve 3 is lowered into the hole with the drill rod 1 and is always located below the drill bit 2, which can provide immediate support for the upper complex loose stratum, avoiding accidents such as hole collapse and drill bit burying, and solving the problem of hole formation in loose stratum by using rotary drilling rig alone; after drilling to the bedrock surface, the sleeve 3 is left to support the wall, and the rotary drilling rig is switched to drill into the bedrock, fully utilizing the strong rock-embedding capability of the rotary drilling rig to meet the rock penetration depth requirement of hard rock stratum, making up for the deficiency of the long spiral pile driver in cutting hard rock; finally, the long spiral pile driver pumps concrete and synchronously lifts the drill rod 1 and the sleeve 3, which can not only ensure continuous filling of the hole body to avoid empty holes or broken piles, but also ensure the integrity of the pile body with the help of the continuous supporting effect of the sleeve 3 during the pouring process. Combined with the cooperation of each step, the unification of stable hole formation in the upper part of the complex stratum, accurate verticality control and efficient rock penetration in the lower part is achieved, which significantly improves the construction quality and efficiency of the first type of pile body, enhances the integrity and anti-seepage effect of the anti-seepage structure formed by the pile engagement, and reduces the construction cost and safety risk.

[0040] Embodiment 2 The difference between this embodiment and embodiment 1 is that the first type of pile body is replaced by a second type of pile body, and the second type of pile body is replaced by a first type of pile body. Figure 4 and Figure 5The sleeve 3 has a grouting channel 31 on its wall, a grouting port 32 communicating with the grouting channel 31 at its top, and multiple grout outlets 33 communicating with the grouting channel 31 at its lower end. These outlets 33 are arranged at intervals around the sleeve 3 and are equipped with one-way valves. After drilling is completed, the grout outlets 33 are at the same height as the drill bit 2 (e.g., ...). Figure 4 (As shown).

[0041] When concrete is pumped into the pile hole using a concrete pump, and when it reaches the bedrock surface, simultaneously with the pumping of concrete, the first and second power heads are started to synchronously lift the drill rod 1 and the sleeve 3. At the same time, a thick slurry containing a quick-setting agent is injected into the wall of the sleeve 3 through the grouting port 32, allowing the slurry to be injected outside the sleeve 3. A high-efficiency aluminate-based quick-setting agent can be selected to meet the requirement of rapid support strength formation.

[0042] As drill pipe 1 and sleeve 3 are continuously and synchronously raised, the grout outlet 33 rises with sleeve 3. Thick mud is continuously injected into the annular gap outside sleeve 3 through multiple circumferentially spaced grout outlets 33 via grouting channel 31. The injected thick mud solidifies rapidly due to the action of the quick-setting agent, forming a temporary rigid support layer tightly attached to the outer wall of sleeve 3. This layer immediately replaces sleeve 3 to provide constraint, preventing ground collapse from damaging the pile forming quality and ensuring construction safety.

[0043] During this process, the one-way valve automatically closes when grouting is paused or the pressure decreases, effectively preventing water, slag, or uncured concrete in the stratum from flowing back into the grouting channel 31, ensuring the continuous and stable operation of the grouting system. Grouting stops when the drill rod 1 and sleeve 3 are completely pulled out of the pile hole, at which point the thick mud slurry has formed a complete solidified support structure on the outside of the pile body.

[0044] The rapidly setting, thick mud can tightly bond with the surrounding strata (sand, gravel, loose soil, etc.), serving as a "transition layer" between the pile and the strata, significantly increasing the contact area and friction between the pile and the strata. In complex strata, this enhanced bonding force can effectively resist lateral displacement or settlement of the pile during subsequent stress processes, making it particularly suitable for areas with uneven geology, providing more stable mechanical support for the seepage-proof structure formed by a certain type of pile.

[0045] The solidified mud layer is dense and adheres tightly to the strata and pile concrete, forming an additional sealing barrier. For upper high-permeability gravel strata or loose layers with fissures, this mud layer can fill stratum pores, seal fissures, and block the seepage path of groundwater along the outside of the pile or stratum gaps.

[0046] Example 3 The difference between this embodiment and Embodiment 2 is that, referring to... Figure 6 and Figure 7When the second power head is used to press down the sleeve 3, a thin mud slurry containing lubricant is injected into the sleeve 3 through the grouting port 32, so that the thin mud slurry is injected to the outside of the sleeve 3.

[0047] Before starting the second power head to drive the sleeve 3 downwards, the grouting pump is first turned on for "pre-grouting," allowing the thin mud slurry to fill the grouting channel 31 and overflow slightly from the outlet 33, ensuring no air remains in the channel. Then, the second power head is started to drive the sleeve 3 downwards, while the grouting pump continues to operate: the grouting pressure is slightly higher than the lateral pressure of the formation, ensuring that the slurry can effectively penetrate to the gap between the outer wall of the sleeve 3 and the formation, while avoiding excessive pressure that could disturb the loose formation; the grouting flow rate is dynamically matched with the downward speed of the sleeve 3 to ensure that the outer wall of the sleeve 3 is always covered with a continuous mud film. The injection of thin mud slurry is stopped when the sleeve 3 is driven 1-2 meters above the bedrock surface.

[0048] During the pressing process of sleeve 3, injecting a thin mud slurry containing lubricant into the outer periphery of sleeve 3 can significantly reduce the frictional resistance between sleeve 3 and the formation, improving pressing efficiency and equipment safety. In complex formations (such as sand and gravel layers, hard clay layers), direct cutting of sleeve 3 can easily generate huge frictional resistance due to the interlocking of formation particles and the adsorption of clay, which may lead to overload of the second power head, deformation of sleeve 3, or pressing stagnation. However, the thin mud slurry containing lubricant forms a continuous lubricating film on the outer wall of sleeve 3 through the slurry outlet 33, which can reduce the coefficient of friction, allowing sleeve 3 to cut into the formation more smoothly, reducing equipment energy consumption and failure risk.

[0049] Complex strata often contain sharp gravel, rock fragments, or hard nodules. When the sleeve 3 is pressed down directly, friction and collision can easily cause wear on the outer wall (especially at the lower cutting edge). The lubricating film formed by the thin mud can isolate the sleeve 3 from the hard particles in the strata, reducing scratching and impact damage caused by direct contact. At the same time, the thin mud can form a protective film on the surface of the sleeve 3, slowing down the erosion of the sleeve 3 by groundwater or corrosive media in the strata, and extending the service life of the sleeve 3.

[0050] The loose strata consist of loose sand or silt layers. Rapid pressing of sleeve 3 can easily trigger sand inrush or collapse of the surrounding soil. After the thin mud is injected, it can penetrate into the gaps between the strata and temporarily cement the loose particles to form a "buffer layer". This reduces the squeezing and disturbance of the strata caused by the pressing of sleeve 3 and fills the pores created by the cutting of sleeve 3, preventing the surrounding soil from becoming unstable.

[0051] After the thin mud is injected, some of it will remain in the gap between the sleeve 3 and the formation. Even when the sleeve 3 is stationary, it can maintain a certain degree of lubrication, which can reduce the starting resistance when the sleeve 3 is lifted synchronously in the future. This makes the coordinated lifting of the drill rod 1 and the sleeve 3 more stable, and indirectly ensures the control accuracy of the verticality of the pile during the concrete pouring process.

[0052] Furthermore, when the sleeve 3 is pressed down to 1-2m above the bedrock surface, the injection of thin mud is stopped, and thick mud is injected instead, while pressing down and injecting thick mud until the drill bit 2 reaches the bedrock surface. The second power head is disengaged from the sleeve 3, the long spiral pile driver is removed, and the rotary drilling rig is positioned. When the rotary drilling rig begins drilling into the bedrock, the injected thick mud enters the static solidification stage. In the annular gap at the interface between the gravel layer and the bedrock, the thick mud gradually loses its fluidity, and the cement and quick-setting agent play their role, solidifying to form a transitional reinforcement layer around the borehole wall. For the weak section at the interface between loose strata and bedrock, which is prone to borehole collapse, the transitional reinforcement layer is formed by injecting thick mud in advance, and the mud is allowed to initially solidify during the rotary drilling time, enhancing the stability of the borehole wall at the interface.

[0053] The interface between loose strata and bedrock, due to abrupt geological changes (loose upper layer, hard lower layer), is the most prone to borehole collapse during drilling. The sand and gravel lack cohesion, and when the constraint from the underlying bedrock suddenly weakens, they are easily collapsed into the borehole under drilling disturbances, especially under the influence of groundwater, which can easily lead to "sand inrush and drill bit burial." The pre-injected thick mud can fully fill the gaps between sand and gravel particles and the annular space between the sleeve 3 and the strata. The reinforcement layer formed after its initial setting can bind the loose sand and gravel into a whole, while also tightly adhering to the underlying bedrock surface, forming a rigid transition barrier to resist lateral pressure from the strata and reduce the risk of borehole collapse at the interface. During rotary drilling, the mud can complete the transition from flowing to initial setting without additional waiting time; the set reinforcement layer provides a stable working boundary for the rotary drill bit 2, preventing interface instability caused by drilling vibrations.

[0054] like Figure 7 As shown, on sleeve 3, the lower grout outlet 33 is angled downwards, the middle grout outlet 33 is horizontal, and the upper grout outlet 33 is angled upwards. This allows the thick mud slurry to both cover the bottom of the sand and gravel layer upwards and penetrate downwards to near the bedrock surface, forming an "umbrella-shaped" reinforcement zone. This expands the grouting protection range without additional equipment and enhances the sealing of the upper and lower interfaces of the transition section. When injecting thin mud slurry downwards and thick mud slurry upwards, the different injection directions allow for a more uniform distribution of the mud slurry within the formation.

[0055] Multiple grout outlets 33 are spirally distributed around the sleeve 3, forming a spiral grouting trajectory. The spiral grouting trajectory allows the thick mud to form a continuous annular reinforcement layer in the transition section, avoiding grouting blind spots, achieving uniform coverage of the mud around the borehole wall, and improving the filling effect on complex formation fissures.

[0056] The spiral-shaped slurry outlets 33 rotate with the sleeve 3, and the slurry continuously spreads along the 360° spiral trajectory, which can cover all angle areas around the borehole wall. Even in complex strata (such as sand and gravel layers with irregular fractures), it can ensure that the thick mud slurry fills each gap evenly.

[0057] In complex strata, fractures and pores are often irregularly distributed (such as oblique fractures and intersecting pores). The fixed diffusion direction of grout from traditional straight grout outlets is difficult to adapt to irregular gaps. However, the spiral trajectory of the grout has the characteristic of "multi-angle penetration": the downward and upward sloping grouting at the bottom can track the oblique fractures on the bedrock surface, the horizontal grouting in the middle can cover the transverse gaps, and the continuity of the spiral line allows the filling areas at different angles to connect with each other, forming a "seamless" reinforcement network.

[0058] The spiral trajectory, through "continuous grouting + rotational diffusion," can cover a larger area with the same grouting volume. At the same time, the spiral distribution reduces the "grouting repair" process caused by localized missed grouting, shortens the grouting time per pile, and reduces overall construction costs.

[0059] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0060] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application 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 this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0061] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A construction method for long spiral interlocking piles under complex geological conditions for water conservancy seepage prevention, characterized in that, Includes the following steps: Construct a guide wall at the target pile location to locate the borehole position; A long spiral pile driver is provided, which is configured as a dual-powered machine with a first power head and a second power head. The first power head is connected to a drill rod (1) and is used to drive the drill rod (1) to drill. The drill rod (1) is connected to a drill bit (2). The second power head is detachably connected to a sleeve (3) sleeved outside the drill rod (1) and is used to press down the sleeve (3). Align the drill bit (2) with the hole position, use the second power head to press down the sleeve (3) to a preset depth, and then use the first power head to drive the drill rod (1) to drill. The sleeve (3) and the drill rod (1) are drilled down synchronously. The bottom surface of the sleeve (3) is always below the drill bit (2) until the drill bit (2) drills to the bedrock surface elevation to form a pile hole. After drilling is completed, the drill rod (1) is lifted to disengage the second power head from the sleeve (3), leaving the sleeve (3) inside the pile hole; A rotary drilling rig is used to drill into the bedrock from the pile hole until the target depth of the bedrock is reached; After the rotary drilling is completed, the rotary drilling rig is removed, and the drill rod (1) of the long spiral pile driver is lowered to the bottom of the pile hole. Concrete is pumped into the pile hole using a concrete pump. When the concrete reaches the bedrock surface, the drill rod (1) and the sleeve (3) are lifted while pumping concrete until the pressure grouting is completed.

2. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention as described in claim 1, characterized in that, "Constructing a guide wall at the target pile location to locate the borehole" includes the following steps: Mechanically excavate the guide wall trench at the target pile location; Guide wall reinforcement bars are arranged in the guide wall trench; Install guide wall formwork outside the guide wall reinforcement; Concrete is poured into the guide wall template. After the concrete strength meets the requirements, the guide wall template is removed to form the guide wall positioning holes.

3. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention according to claim 1, characterized in that, The concrete pumped into the pile hole is ultra-retarded concrete with an initial setting time of 24–30 hours; and / or During the synchronous drilling process of the sleeve (3) and the drill rod (1), the bottom surface of the sleeve (3) is always located below the drill bit (2), with a distance of 0.5 to 1m.

4. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention according to claim 1, characterized in that, "Using a concrete pump to pump concrete into the pile hole, when the concrete reaches the bedrock surface, while pumping the concrete, raise the drill rod (1) and the sleeve (3) until the pressure grouting is completed" includes the following steps: Concrete is pumped into the drill rod (1); After the drill rod (1) is filled with concrete and reaches the preset pressure, the drill rod (1) is pulled up, and the drilling speed is matched with the concrete pumping speed. When the concrete is pumped into the bedrock surface, the drill rod (1) and the sleeve (3) are pulled up at the same time. While pumping concrete, the drill rod (1) and the sleeve (3) are lifted. During the lifting process, the bottom surface of the sleeve (3) is always below the drill bit (2) and the distance between them is 0.5 to 1m.

5. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention according to claim 1, characterized in that, The sleeve (3) has a grouting channel (31) on its wall. The top of the sleeve (3) has a grouting port (32) that communicates with the grouting channel (31). The lower end of the sleeve (3) has multiple grouting ports (33) that communicate with the grouting channel (31). The multiple grouting ports (33) are arranged circumferentially around the sleeve (3) and are equipped with one-way valves. After the sleeve (3) is drilled down, the grouting ports (33) are at the same height as the drill bit (2). When concrete is pumped into the pile hole using a concrete pump, and when it reaches the bedrock surface, while pumping the concrete, the drill rod (1) and the sleeve (3) are lifted. At the same time, thick mud containing a quick-setting agent is injected into the sleeve (3) wall through the grouting port (32), so that the thick mud is injected outside the sleeve (3).

6. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention according to claim 5, characterized in that, When the second power head is used to press down the sleeve (3), a thin mud slurry containing lubricant is injected into the sleeve (3) through the grouting port (32), so that the thin mud slurry is injected outside the sleeve (3).

7. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention according to claim 6, characterized in that, When the sleeve (3) is pressed down to 1-2m above the bedrock surface, stop injecting the thin mud and start injecting the thick mud. Continue injecting the thick mud while pressing down until the drill bit (2) drills to the bedrock surface.

8. The construction method for long spiral interlocking piles under complex geological conditions for water conservancy seepage prevention according to claim 7, characterized in that, On the sleeve (3), the slurry outlet (33) located at the lower part is obliquely downward, the slurry outlet (33) located in the middle part is horizontal, and the slurry outlet (33) located at the upper part is obliquely upward.

9. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention according to claim 8, characterized in that, Multiple grout outlets (33) are arranged in a spiral pattern around the sleeve (3), forming a spiral grouting trajectory.

10. The construction method for long spiral interlocking piles under complex geological conditions for hydraulic seepage prevention according to claim 1, characterized in that, After the pressure grouting is completed, the operation is repeated to form multiple piles of the same type arranged at intervals. Before the initial setting of the piles of the same type, the rotary drilling rig is used to drill between adjacent piles of the same type to cut the adjacent piles of the same type and the soil to form a central pile hole. Concrete is poured into the central pile hole to form a second type of pile body. A second type of pile body is formed between each two adjacent first type pile bodies, so that each first type pile body and each second type pile body are arranged in a one-to-one interlocking manner.

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