A double-machine cooperative pile-forming method for construction waste backfill layer and seepage stratum

Abstract

The application discloses a double-machine cooperative pile-forming method for building waste backfill layers and seepage strata, and belongs to the technical field of building construction. The method comprises the following steps: flattening and compacting a construction site, measuring and lofting to determine a pile position, using a rotary drilling machine to pre-form a hole at the pile position, sinking a steel casing into the pre-formed hole to a stable stratum, injecting wall protection mud between the steel casing and the hole wall to form a composite wall protection structure, using a long spiral drilling machine to drill in the composite wall protection structure to a design depth, continuously pressing and pouring concrete through a hollow drill rod, using an intelligent monitoring system to link and control the drilling and pouring processes, and synchronously lifting the drill rod during the pressing and pouring process; after the concrete pouring is completed, using a vibrating inserter to implant a steel reinforcement cage into the concrete to form a reinforced concrete cast-in-place pile; the double-machine cooperative pile-forming method for building waste backfill layers and seepage strata is used, and the construction efficiency, pile-forming quality, economic benefits and environmental friendliness are comprehensively improved.

Description

A dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata. Background Technology

[0002] As urban renewal projects expand into the transformation of existing sites, pile foundation construction increasingly traverses complex geological environments where backfill layers of construction waste intertwine with strata containing seeping groundwater. These strata contain numerous hard obstacles such as concrete blocks and gravel of varying sizes, accompanied by active groundwater activity, posing a severe challenge to traditional pile-forming techniques. Currently, construction methods using single equipment (such as long spiral drilling rigs) perform poorly in these strata: they are prone to jamming and machine shutdowns when facing large-diameter obstacles; after drilling, the risk of borehole instability and collapse is high due to groundwater seepage and inter-process intervals; and during subsequent grouting, inaccurate parameter control often leads to problems such as pile diameter reduction. These drawbacks collectively result in low construction efficiency, unstable pile quality, long single-pile construction time, and a need to increase the proportion of Class I piles. Therefore, a construction method is needed that can effectively address the dual challenges of construction waste obstacles and groundwater seepage, achieving efficient and high-quality pile formation. Summary of the Invention

[0003] The purpose of this invention is to provide a dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides a dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata, comprising the following steps:

[0005] S1. Level and compact the construction site, set up drainage ditches around the site, and measure and set out the pile positions.

[0006] S2. A rotary drilling rig is used to pre-drill holes at the pile location, with the hole diameter enlarged to 1.1-1.3 times the designed pile diameter, in order to break up large-diameter obstacles in the construction waste backfill layer and form a guide hole. The drilling parameters of the rotary drilling rig are collected and controlled in real time by an intelligent monitoring system. The intelligent monitoring system is used to collect drilling parameters and establish a control model.

[0007] S3. Sink a steel casing into the pre-drilled hole to a stable formation, and inject wall-protecting mud between the steel casing and the hole wall to form a composite wall-protecting structure for stabilizing the hole wall of the seepage formation.

[0008] S4. A long spiral drilling rig is used to drill to the designed depth inside the composite wall structure. At the same time, concrete is continuously pressure-poured through its hollow drill rod. The drilling and grouting process is controlled in conjunction with an intelligent monitoring system. The drill rod is lifted synchronously during the pressure-pouring process.

[0009] S5. After the concrete pouring is completed, a vibratory inserter is used to insert the reinforcing cage into the concrete that has not yet set, forming a reinforced concrete cast-in-place pile.

[0010] Preferably, the rotary drilling rig in S2 is equipped with a rock-socketed cutting tooth drill bit with a high torque of 360 kN·m, and the pre-drilled hole diameter is increased to 1.2 times the designed pile diameter.

[0011] Preferably, when the rotary drilling rig in S2 drills into the construction waste backfill layer, it uses a rock-embedded cutting tooth drill bit and the drilling speed is controlled to be no more than 0.5 m / min; when the rotary drilling rig drills into the original soil layer under the construction waste backfill layer, it switches to an ordinary alloy drill bit and the drilling speed is increased to no more than 1.2 m / min.

[0012] Preferably, the specific operation of sinking the steel casing in S3 is as follows: a hydraulic vibratory hammer with an excitation force of not less than 650kN is used to sink the steel casing, so that the lower end of the steel casing sinks into the stable stratum to a depth of not less than 1.5m.

[0013] Preferably, the wall-protecting slurry injected in S3 is bentonite slurry with a specific gravity of 1.18-1.22 g / cm³. 3 The viscosity is 25-30s.

[0014] Preferably, the intelligent monitoring system in S4 achieves final hole drilling by controlling the drilling pressure and rotation speed of the long spiral drilling rig, wherein the drilling pressure is controlled at 80-120 kPa and the rotation speed is controlled at 18±2 rpm.

[0015] Preferably, the intelligent monitoring system in S4 dynamically adjusts the drilling speed using the following formula:

[0016] ;

[0017] in, To increase drilling speed, For pumping volume, Where is the drill pipe radius. The filling coefficient is set between 1.1 and 1.3.

[0018] The intelligent monitoring system can intelligently adjust the drilling speed and pumping volume with a synchronization rate of no less than 95%.

[0019] Preferably, the concrete used for pressure grouting in S4 is C30 fine aggregate concrete with a spread of 550±50mm and a grouting pressure of 3.0-4.0MPa.

[0020] Preferably, the excitation force of the vibratory inserter in S5 is 50-80kN, and the insertion speed of the reinforcing cage is no more than 0.3m / min.

[0021] Preferably, the maximum particle size of obstacles in the construction waste backfill layer is no greater than 1.5m, and the permeability coefficient of the seepage stratum is 1×10⁻⁶. -4 ~5×10 -3 cm / s.

[0022] Therefore, the present invention employs the above-mentioned dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata, which has the following beneficial effects:

[0023] (1) Through the dual-machine collaborative mechanism of "rotary drilling pre-obstacle breaking" and "long spiral relay pressure grouting", the large-torque rotary drilling rig first breaks and removes large-diameter obstacles, and then the long spiral drilling rig simultaneously completes the final hole and concrete grouting in the protected cavity. Combined with the "steel casing + mud" composite wall protection technology, it blocks and balances groundwater seepage, thereby reducing the risk of stuck drill and hole collapse commonly found in traditional processes.

[0024] (2) The dual-machine relay realizes the close connection and optimization of the process, which helps to increase the daily number of piles; at the same time, the intelligent monitoring system is used to control the core parameters such as drilling pressure, rotation speed, grouting pressure and drilling speed, ensuring the continuity and compactness of concrete grouting, and providing an effective means to improve the proportion of pile integrity (Class I piles).

[0025] (3) By combining the graded hole-forming process (pre-drilling and enlarging the diameter to reserve operating space for subsequent construction, and precise diameter control in the final hole stage) with the parameter linkage model, it is helpful to control the pile-forming accuracy (such as pile diameter deviation) within a better range. This construction method forms a set of technical solutions with clear parameters and clear process, providing a new solution for pile foundation construction under similar complex geological conditions.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 is a flowchart of a dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to the present invention. Detailed Implementation

[0028] The following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] Example

[0030] As shown in Figure 1, this invention provides a dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata, comprising the following steps:

[0031] This embodiment takes a cast-in-place pile with a diameter of 800mm and a length of 28m as an example in an urban renewal project.

[0032] S1. Level the construction site where construction waste is piled up, and use a road roller to compact it to ensure that the site compaction degree is not less than 93% and the foundation bearing capacity is not less than 180kPa, so as to meet the requirements of stable operation of heavy drilling rigs; set up drainage ditches around the site to prevent water accumulation; then, use high-precision measuring instruments (such as RTK equipment) to lay out the pile positions, with the layout accuracy controlled within ±5mm, and use steel bar ends and red paint to clearly mark the pile positions.

[0033] S2. Position a high-torque rotary drilling rig (e.g., an XR400E model with a torque of not less than 360 kN·m) at the pile location. The core of this step is to remove obstacles and form an enlarged guide hole. The drilling parameters of the rotary drilling rig are collected and controlled in real time by an intelligent monitoring system. The intelligent monitoring system is used to collect drilling parameters and establish a control model. In this embodiment, the intelligent monitoring system used is the DMS-500 drilling detection system.

[0034] The drilling rig is equipped with a rock-socketed cutting tooth drill bit (tooth tip hardness HRC62-65). It first drills into the upper construction waste backfill layer (7-10m thick). In this layer, to effectively break up obstacles such as concrete blocks with a maximum particle size not exceeding 1.5m, the drilling speed must be controlled within 0.5m / min, and the verticality must be checked every 1m of drilling to ensure the deviation does not exceed 0.5%. The diameter of the pre-drilled hole formed at this stage needs to be expanded to 1.2 times the designed pile diameter (i.e., Φ800mm pile expanded to Φ960mm) to reserve sufficient space for obstacle avoidance and drilling margin for the subsequent long auger drilling rig. When drilling through the construction waste layer and entering the lower undisturbed soil layer, a regular alloy drill bit can be switched to, and the drilling speed appropriately increased to no more than 1.2m / min, until a depth approximately 500mm deeper than the designed pile depth is reached to ensure space for sediment. After drilling, the sediment thickness at the bottom of the hole should not exceed 30mm.

[0035] S3. To address seepage into the strata below the groundwater level (5m deep in this embodiment) (permeability coefficient approximately 3×10⁻⁶) -4 To mitigate the risk of borehole collapse (cm / s), a composite wall protection structure was immediately installed within the pre-drilled borehole to stabilize the borehole wall in the seepage formation.

[0036] First, a hydraulic vibratory hammer with a high excitation force (not less than 650kN) is used to vibrate and sink a steel casing with a diameter of 1200mm and a wall thickness of 10mm into the stable undisturbed soil layer. The lower end of the casing is buried at a depth of not less than 1.5m to rigidly block the seepage path of shallow groundwater. Simultaneously with the installation of the casing, a specially formulated wall-protecting slurry is injected through the annular gap between the casing and the borehole wall. This slurry is bentonite slurry with a specific gravity controlled at 1.18-1.22 g / cm³. 3 The viscosity is controlled at 25-30s, thereby forming a dense mud cake on the borehole wall. The liquid column pressure of the mud column flexibly balances the external water and soil pressure, forming a stable composite wall protection structure that combines rigidity and flexibility together with the steel casing.

[0037] S4. Under the protection of the composite wall, a long spiral drilling rig (such as the ZY-120 type) is used for final hole drilling and concrete pouring. After the drilling rig is in place, the DMS-500 drilling monitoring system is activated. This system establishes a linkage model between drilling pressure, rotation speed, and pouring pressure. During the drilling process to the design depth (28m), the drilling pressure is intelligently controlled at 80-120kPa, and the rotation speed is controlled at 18±2rpm, thereby accurately controlling the final hole diameter and effectively controlling the pile diameter deviation within an excellent level of +50mm / -30mm. When the design depth is reached, concrete is continuously poured through the hollow drill rod without lifting the drill. The entire pouring process is controlled by the DMS-500 drilling monitoring system: the system monitors the concrete pumping volume in real time and dynamically calculates and adjusts the drill rod lifting speed based on the following formula:

[0038] ;

[0039] in, The drilling speed is measured in m / min. Pumping volume (m) 3 / h), Where is the radius of the drill pipe (m). The filling coefficient is set to 1.1-1.3.

[0040] The DMS-500 drilling monitoring system ensures a high-precision match between the drilling speed and the concrete filling speed by adjusting the drill rod lifting speed. Practice shows that its synchronization rate can reach over 95%. C30 fine aggregate concrete (coarse aggregate size 5-15mm) is used, with a spread of 550±50mm. The grouting pressure is precisely controlled in stages: in the initial grouting stage (pile depth 0-5 meters), a lower pressure of 2.5-3.0MPa is used to avoid dispersing sediment at the bottom of the hole or disturbing the hole wall; in the normal grouting stage (pile depth 5-25 meters), the pressure is maintained at 3.0-3.5MPa to effectively compact the soil around the pile; in the final grouting stage (pile depth over 25 meters to the pile top), the pressure is increased to 3.5-4.0MPa to ensure the concrete at the pile top is fully compacted and to prevent the formation of laitance or loose layers.

[0041] S5. After the concrete pouring is completed and before the initial setting of the concrete, a vibratory inserter (excitation force 50-80kN) is used to vertically vibrate and insert the precast steel cage into the pile body; the insertion speed is controlled within 0.3m / min, and the verticality deviation is ensured to be no more than 1%; after the concrete has cured to the required age, a complete reinforced concrete cast-in-place pile is formed.

[0042] In the project described in this embodiment, a total of 1268 piles were constructed using the method described in this embodiment. After comparison and statistics, the following comprehensive benefits were achieved:

[0043] Efficiency and quality have been significantly improved: the average number of piles completed per day has reached 19, which is about 137.5% more efficient than the traditional process used at the site; the quality of the piles has been significantly improved, with Class I piles accounting for 98.7% as tested by the low strain method.

[0044] Significant economic benefits and material savings: the average construction time for a single pile is reduced by 58.3%; due to effective control of hole formation quality, the concrete filling coefficient remains stable at a low level of 1.08-1.12, saving about 18% of concrete materials compared to traditional processes, and reducing the mechanical failure rate by 74%, resulting in direct economic benefits.

[0045] The project offers significant environmental and social benefits: construction noise is reduced by approximately 25 dB(A), minimizing its impact on surrounding communities; the comprehensive recovery rate of drilling slag exceeds 90%, reducing solid waste emissions; and the overall construction period is shortened by 35%, reducing the long-term disruption of construction activities to urban traffic and the environment.

[0046] Therefore, the present invention adopts the above-mentioned dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata, which systematically solves the technical problem of pile formation in construction waste backfill layers and seepage strata, and simultaneously achieves a comprehensive improvement in construction efficiency, pile quality, economic benefits and environmental friendliness, providing an efficient and reliable solution for pile foundation engineering under similar complex geological conditions.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata, characterized in that, Includes the following steps: S1. Level and compact the construction site, set up drainage ditches around the site, and measure and mark out the pile positions; S2. Use a rotary drilling rig to pre-drill holes at the pile positions, with the hole diameter enlarged to 1.1-1.3 times the design pile diameter, to break up large-diameter obstacles in the construction waste backfill layer and form a guide hole. The drilling parameters of the rotary drilling rig are collected and controlled in real time by an intelligent monitoring system, which is used to collect drilling parameters and establish a control model; S3. Sink a steel casing into the pre-drilled hole to a stable stratum, and inject wall-protecting mud between the steel casing and the hole wall to form a composite wall-protecting structure for stabilizing the hole wall of the seepage stratum; S4. Use a long spiral drilling rig to drill to the design depth within the composite wall-protecting structure, while continuously pressurizing concrete through its hollow drill rod, and use the intelligent monitoring system to control the drilling and grouting process in a coordinated manner, simultaneously lifting the drill rod during the pressurization process; the intelligent monitoring system dynamically adjusts the drilling speed using the following formula: ;in, To increase drilling speed, For pumping volume, Where is the drill pipe radius. The filling coefficient is set at 1.1-1.3; the intelligent monitoring system adjusts the drilling speed and pumping volume with a synchronization rate of no less than 95%; S5, after the concrete pouring is completed, a vibratory inserter is used to insert the reinforcing cage into the concrete that has not yet set, forming a reinforced concrete cast-in-place pile.

2. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 1, characterized in that: The rotary drilling rig in the S2 is equipped with a rock-socketed cutting bit with a high torque of 360 kN·m, and the pre-drilled hole diameter is increased to 1.2 times the design pile diameter.

3. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 2, characterized in that: When drilling into the backfill layer of construction waste, the rotary drilling rig in S2 uses a rock-embedded cutting tooth drill bit and controls the drilling speed to no more than 0.5 m / min. When drilling into the original soil layer under the backfill layer of construction waste, the rotary drilling rig switches to a regular alloy drill bit and increases the drilling speed to no more than 1.2 m / min.

4. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 1, characterized in that, The specific operation for sinking the steel casing in S3 is as follows: a hydraulic vibratory hammer with an excitation force of not less than 650kN is used to sink the steel casing, so that the lower end of the steel casing sinks into the stable stratum to a depth of not less than 1.5m.

5. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 1, characterized in that: The wall-protecting slurry injected in S3 is bentonite slurry with a specific gravity of 1.18-1.22 g / cm³. 3 The viscosity is 25-30s.

6. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 1, characterized in that: The intelligent monitoring system in S4 achieves final hole drilling by controlling the drilling pressure and rotation speed of the long spiral drilling rig, with the drilling pressure controlled at 80-120 kPa and the rotation speed controlled at 18±2 rpm.

7. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 1, characterized in that: The concrete used for pressure grouting in S4 is C30 fine aggregate concrete with a spread of 550±50mm and a grouting pressure of 3.0-4.0MPa.

8. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 1, characterized in that: The excitation force of the vibratory inserter in S5 is 50-80kN, and the insertion speed of the reinforcing cage is no more than 0.3m / min.

9. The dual-machine collaborative pile-forming method for construction waste backfill layers and seepage strata according to claim 1, characterized in that: The maximum particle size of obstacles in the construction waste backfill layer is no greater than 1.5m, and the permeability coefficient of the seepage stratum is 1×10⁻⁶. -4 ~5×10 -3 cm / s.

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