A method and device for intelligent grouting of aeolian sand composite roadbed resources

Abstract

The application belongs to the technical field of road engineering and foundation treatment, and provides a wind-sand composite roadbed resource intelligent grouting construction method and equipment, which comprises the following steps: after the foundation is leveled, wind-sand is used as the main filler to carry out layered paving and compaction of embankment and lower roadbed; grouting point positions are laid out on the lower roadbed layer; high-performance slurry is used to carry out pressure grouting, and based on the real-time collection results of the compaction degree, the penetration pressure-depth curve, the grouting flow, the lifting speed and the grouting amount per unit depth, the opening and closing of the grouting valve, the grouting pressure and the lifting speed are interlocked controlled or adaptively adjusted to form a continuous and uniform cement column reinforced body; the column top is controlled to be higher than the top surface of the lower roadbed to form a protruding section and is maintained until the preset strength is reached; then, geogrid is laid to make the column top protruding section penetrate and embed in the grid mesh, and the upper roadbed and the pavement structure are continuously constructed; the application takes into account the resource utilization of wind-sand, the collaborative utilization of industrial solid waste and the intelligent control in the construction process.

Description

Technical Field

[0001] This invention belongs to the field of road engineering and foundation treatment technology, specifically relating to a resource-based intelligent grouting construction method and equipment for aeolian sand composite roadbed. Background Technology

[0002] Aeolian sand is widely distributed in arid and semi-arid regions of Northwest my country, with abundant reserves and convenient access, providing a solid foundation for engineering applications. In areas where high-quality fill materials are insufficient and transportation costs are high, using aeolian sand as roadbed fill material can help reduce material transportation costs and improve the utilization rate of local materials.

[0003] However, aeolian sand itself has fine particles, a loose structure, and weak interparticle cohesion, resulting in problems such as difficulty in compaction, low bearing capacity, and insufficient resistance to deformation, making construction quality control quite challenging. Due to material performance limitations, existing aeolian sand subgrades are mostly used in low subgrade and gentle slope conditions. For projects with higher requirements for stability and bearing capacity, such as high subgrade and steep slopes, it is usually necessary to install support structures such as cement arches, which increases construction procedures and project costs. In addition, existing aeolian sand subgrade construction often uses methods such as water settling to improve compaction, but these methods lack unified and clear standards and specifications for construction parameter control, quality inspection, and acceptance evaluation, resulting in insufficient stability and controllability of project quality, making it difficult to fully meet the requirements of high-grade highways for subgrade bearing capacity, deformation, and durability.

[0004] Against this backdrop, how to fully utilize the advantages of locally sourced aeolian sand and further combine it with resource-based materials such as industrial solid waste to form a composite roadbed structure that balances load-bearing capacity, deformation control, and long-term durability has become a pressing technical problem in this field. In particular, a construction method and supporting equipment are needed that can first compact the aeolian sand in layers, and then perform grouting reinforcement at appropriate locations to form a composite roadbed structure where the compacted aeolian sand layer and the grouting reinforcement work together. This would improve the overall performance of the roadbed while simultaneously utilizing local materials and recycling solid waste. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a resource-based intelligent grouting construction method and equipment for aeolian sand composite roadbed, thereby solving the problems in the prior art. The technical solution adopted by this invention is as follows: A resource-efficient intelligent grouting construction method for aeolian sand composite roadbed includes the following steps: Step 1: Level and treat the foundation surface; Step 2: Use aeolian sand as filler to spread and compact the embankment and subgrade in layers, so that the aeolian sand forms a compacted layer that meets the construction requirements; Step 3: Mark out the grouting points on the lower subgrade and determine the reinforcement depth hx, column diameter D, and spacing S of the grouting columns. Step 4: Drive the grouting needle at each grouting point to penetrate from the top surface of the lower subgrade to the reinforcement depth hx, input cement grout into the grouting needle and perform pressure grouting during penetration or lifting, while controlling the lifting speed v and grouting flow rate of the grouting needle to keep the grouting amount q per unit depth within the set range, thereby forming a cement column reinforcement body with a column diameter of D in the lower subgrade. Step 5: Control the top elevation of the cement column reinforcement so that the top of the column forms a protruding section relative to the top surface of the lower subgrade. After the grouting is completed, seal and moisturize the cement column reinforcement until it reaches the preset strength. Step 6: Lay geogrid on the top surface of the lower subgrade, so that the protruding section of the cement column reinforced body passes through and falls into the mesh of the geogrid, thereby forming a pore-embedded connection between the geogrid and the cement column reinforced body. Step 7: Continue construction of the upper subgrade and pavement structure on the geogrid.

[0006] Furthermore, the reinforcement depth hx is the effective reinforcement depth of the grouting column from the top of the lower subgrade downwards.

[0007] Furthermore, the aeolian sand filler is laid in layers, with each layer having a thickness of 30cm. After laying, it is compacted to form a compacted layer.

[0008] Furthermore, cement slurry includes cement, mineral admixtures, and additives.

[0009] Furthermore, before step 4, the procedure also includes determining the grouting construction acceptance conditions by testing the compaction degree of the subgrade layer, including: Representative points were selected to test the compaction degree Ki of the lower roadbed, and the penetration pressure variation curve P(h) at different depths was collected simultaneously during the grouting needle penetration process; a fitting relationship between compaction degree Ki and penetration pressure P(hj) was established at discrete depth points hj: P(hj)=αj+βj·Ki; Using the penetration pressure corresponding to the target compaction degree K0 as the entry threshold, the pressure threshold curve Pmin(h) is obtained; the penetration pressure is collected in real time at the grouting point, and when the penetration pressure is not lower than the pressure threshold of the corresponding depth, the grout outlet valve is opened to perform pressure grouting.

[0010] Furthermore, in step 4, during the pressure grouting process, adaptive control is adopted, including: based on the real-time collected compaction degree Ki, penetration pressure variation curve P(h) with depth, grouting flow rate Q, lifting speed v, and grouting volume per unit depth q, the current construction conditions are identified online, and the grouting flow rate, grouting pressure, and lifting speed are dynamically adjusted so that the grouting volume per unit depth q and grouting pressure remain constant or within the set fluctuation range.

[0011] Furthermore, the grouting points are arranged in a grid or quincunx pattern to form a group of cement-reinforced columns.

[0012] A resource-based intelligent grouting construction equipment for aeolian sand composite roadbed, employing the aforementioned resource-based intelligent grouting construction method for aeolian sand composite roadbed, includes: a vehicle body, a control system, a power system, a grouting system, and a mixing system; The grouting system includes a steel frame, hydraulic rods, and grouting needles. The steel frame is connected to the hydraulic rods. The steel frame is installed on the vehicle body. The output end of the hydraulic rods is connected to the grouting needles. The grouting needle tube includes a tube body with a one-way baffle at the lower end. The one-way baffle is bolted to the tube body. When the grouting needle tube penetrates the roadbed downwards, the one-way baffle is tightly fitted to the lower end of the tube body and seals the grout outlet under the upward reaction force of the roadbed. When the grouting needle tube is lifted upwards, the one-way baffle rotates around the hinge point under its own weight, causing the lower end of the tube body to open.

[0013] A wind-blown sand composite roadbed structure, based on the aforementioned intelligent grouting construction method for wind-blown sand composite roadbed, includes a subgrade, a group of cement-reinforced columns set inside the subgrade, a geogrid laid on the top surface of the subgrade and embedding the protruding sections of the cement columns, and an upper roadbed set on the geogrid.

[0014] The present invention has the following beneficial effects: (1) Controllable column quality: By matching the lifting speed with the grouting flow rate, the grouting volume per unit depth is controlled, so that the column is continuous and uniform, reducing dispersion and rework rate; (2) Reliable interface connection: The column top protrusion is inserted into the geogrid mesh to form a pore-embedded connection, which improves the joint stress-bearing capacity of column-grid-superstructure and weakens interlayer slippage; (3) Adapt to the desert construction environment: Grouting is carried out after the subgrade is formed, which reduces the dependence on construction water supply and wet curing conditions. Combined with closed moist curing and early strength assessment, it is conducive to fast construction and quick entry into the next process. (4) Regional optimization: The transition area between the wheel track and the shoulder can be densely arranged to enhance the load-bearing capacity and deformation resistance of key stress areas and improve the economic efficiency of the structure. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view of the roadbed structure designed in this invention; Figure 2 This is a flowchart of the roadbed construction process; Figure 3 This is a schematic diagram of an intelligent control system; Figure 4 This is a structural schematic diagram of the integrated compaction degree detection and grouting construction machinery of the present invention; Figure 5 This is a schematic diagram of the steel frame structure of the integrated construction machinery of the present invention; Figure 6 This is a schematic diagram of the grouting system structure of the integrated construction machinery of the present invention; Figure 7 This is a partial schematic diagram of the grouting needle of the present invention; In the diagram: 1 Geogrid; 2 Cement grout consolidation and reinforcement column; 41 Mixing cylinder; 42 Discharge valve; 43 Mixing propeller; 44 Cement grout conduit; 51 Pressurization device; 52 Conduit; 61 Electric leveling foot screw; 62 Hydraulic rod; 63 Pressure sensor; 64 Grouting disc; 65 Grouting needle; 66 Grout inlet; 67 Laser positioner; 8 Control room; 81 Steel frame; 82 Guide rail; 83 Pulley; 9 Power system; 10 Driver's cab. Detailed Implementation

[0016] The following will be described in conjunction with embodiments of the present invention. Figures 1-7 The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0017] like Figure 2 , Figure 3 This invention proposes a resource-based intelligent grouting construction method for aeolian sand composite roadbed, comprising: Step 1: First, level and treat the foundation surface; Step 2: Use aeolian sand as filler to spread and compact the embankment and subgrade in layers, so that the aeolian sand forms a compacted layer that meets the construction requirements; Step 3: Mark out the grouting points on the lower roadbed and determine the reinforcement depth hx, column diameter D and arrangement spacing S of the grouting columns according to the target bearing capacity, deformation control index or roadbed design parameters. Step 4: Drive the grouting needle at each grouting point to penetrate from the top surface of the lower subgrade to the reinforcement depth hx, input high-performance cement grout into the needle, and perform pressure grouting during the penetration or lifting process. At the same time, control the lifting speed v and grouting flow rate of the grouting needle to keep the grouting amount q per unit depth within the set range, thereby forming a cement column reinforcement body with a column diameter of D in the lower subgrade. Step 5: Control the top elevation of the cement column reinforcement so that the top of the column is slightly higher than the top surface of the lower subgrade and forms a protruding section. After the grouting is completed, seal and moisturize the cement column reinforcement until the cement column reinforcement reaches the preset early strength required for laying the geogrid. Step 6: Lay a geogrid on the top surface of the lower roadbed, so that the protruding section of the cement column reinforcement body passes through and falls into the mesh of the geogrid, thereby forming a pore-embedded connection between the geogrid and the cement column reinforcement body. Step 7: Continue the construction of the upper subgrade and pavement structure on the structural layer after the geogrid has been laid.

[0018] Furthermore, the aeolian sand filler is laid in layers, with each layer being 30cm thick. After laying, it is compacted to form a compacted layer. The compaction process is carried out in accordance with the relevant national standards, including but not limited to dry compaction and vibration compaction.

[0019] Furthermore, the reinforcement depth hx is the effective reinforcement depth of the grouting column from the top of the lower roadbed downwards, and is determined by the target bearing capacity or deformation control index.

[0020] Furthermore, the column diameter D is the equivalent diameter of the cement column formed by grouting, which is determined by the bearing deformation control index and the grouting point layout parameters. The layout parameters include at least the column spacing and layout form; and D is jointly controlled by the grout mix ratio, grouting pressure, aeolian sand pore conditions and grouting volume q per unit depth.

[0021] Furthermore, the high-performance cement slurry includes cement, mineral admixtures, and additives; at least a portion of the mineral admixtures are industrial solid waste resource recovery materials, including one or more of fly ash, granulated blast furnace slag powder, steel slag powder, desulfurized gypsum, and modified red mud powder; the additives include one or more of water-reducing agents, micro-expansion components, and crack-resistant fibers to improve the early strength, crack resistance, and resource utilization level of the slurry.

[0022] Furthermore, before construction in step 4, the process includes determining the grouting construction access conditions by detecting the compaction degree of the subgrade. Specifically, representative points are selected to detect the subgrade compaction degree Ki, and the penetration pressure variation curve P(h) at different depths is simultaneously collected during the grouting needle penetration process. A fitting relationship between compaction degree Ki and penetration pressure P(hj) is established at discrete depth points hj: P(hj) = αj + βj·Ki. The penetration pressure corresponding to the target compaction degree K0 is used as the access threshold to obtain the pressure threshold curve Pmin(h). P(h) is collected in real time at the grouting point. Pressure grouting can only be implemented by opening the grout outlet valve when P(h) is not lower than Pmin(h) at the corresponding depth.

[0023] Furthermore, this invention employs adaptive control, meaning the control system identifies the current construction conditions online based on real-time collected parameters such as compaction degree Ki, penetration pressure versus depth curve P(h), grouting flow rate Q, lifting speed v, and grouting volume per unit depth q. It then dynamically adjusts the grouting flow rate, grouting pressure, and lifting speed to maintain the grouting volume per unit depth q and grouting pressure at a constant or within a set fluctuation range, thereby improving the continuity, uniformity, and construction quality stability of the columnar reinforced body. The grouting volume per unit depth satisfies q = Q / v.

[0024] Preferably, at sampling time k, the data acquisition module acquires the compaction degree Ki, grouting depth hk, penetration pressure P(k), grouting flow rate Q(k), and lifting speed v(k), and calculates the grouting volume per unit depth q(k) = Q(k) / v(k). The working condition identification module determines the current construction state based on the working condition parameter vector θk = [Ki, hk, ΔP(k), η(k)], where ΔP(k) = P(k) - Pmin(hk) is the pressure margin relative to the pressure threshold curve, and η(k) is the grout state parameter. The control system determines the target grouting volume per unit depth q*(k), target pressure P*(k), and corresponding control gains a1(θk), a2(θk), b1(θk), and b2(θk) based on the working condition parameter vector θk.

[0025] When the compaction degree Ki is lower than the set threshold or the measured penetration pressure P(k) is lower than the pressure threshold curve Pmin(hk) at the corresponding depth, the system interlocks and closes the grout outlet valve; after the access conditions are met, the deviation of the grouting volume per unit depth and the pressure deviation are respectively: eq(k)=q*(k)-q(k); eP(k)=P*(k)-P(k) And update the execution quantity according to the following formula: Q(k+1)=sat[Q(k)+a1(θk)·eq(k)+a2(θk)·eP(k)] v(k+1)=sat[v(k)-b1(θk)·eq(k)-b2(θk)·eP(k)] Where sat(x) = min(max(x, xmin), xmax), xmin and xmax are the upper and lower limits within the allowable range of the equipment; at the same time, the rate of change of the grouting flow rate and the lifting speed are limited, satisfying: |Q(k+1)-Q(k)|≤ΔQmax |v(k+1)-v(k)|≤ΔVmax This is to avoid abrupt changes in control parameters and improve the consistency of column formation quality. Through the above methods, the control system can adjust the grouting flow rate and lifting speed online according to different compaction states, grouting depths, and construction conditions, achieving a synergistic effect between interlocking control and adaptive control.

[0026] As an alternative implementation, the control system may also employ a constrained model predictive control method, with grouting flow rate Q and lifting speed v as control variables, and grouting volume per unit depth q and grouting pressure P as control targets. The control quantity is continuously optimized in the prediction time domain to keep q and P within the set range, while simultaneously meeting the equipment's allowable range and rate of change limits.

[0027] Furthermore, the sealing and moisturizing maintenance in step S5 includes covering with moisturizing material and spraying or sprinkling water for moisturizing; the preset early strength is determined by the strength of the specimen under the same conditions, or by the penetration resistance or rebound index reaching a set threshold.

[0028] Furthermore, the protrusion height of the top of the cement column solidified body relative to the top surface of the lower subgrade is Δh, and Δh is used to allow the top of the column to pass through the geogrid mesh and form an embedded connection.

[0029] Furthermore, the mesh size of the geogrid is matched with the column diameter D, so that the protruding section of the cement column reinforcement can pass through the mesh and the geogrid ribs form a mechanical interlock with the outer side of the column along the column circumference.

[0030] Furthermore, the grouting points are arranged in a grid or quincunx pattern to form a group of cement-reinforced columns, with the spacing between any two adjacent reinforced columns being 0.8 to 1.5 meters. The grouting is appropriately densified in areas of greater stress, including the transition zone between the wheel track and the shoulder; the column spacing Sw in the wheel track area is smaller than the column spacing So in the non-wheel track area.

[0031] like Figures 4-7The present invention also provides a resource-based intelligent grouting construction equipment for aeolian sand composite roadbed. This equipment is a special integrated equipment for high-performance cement grouting aeolian sand roadbed construction. The whole consists of a vehicle body, control system, power system 9, grouting system and mixing system. Each system is modularly arranged to meet the mobility and precision requirements of aeolian sand roadbed on-site construction.

[0032] The vehicle body is equipped with a control system, a power system 9, a grouting system and a mixing system, a control room 8, and a driver's cab 10; The grouting system includes a steel frame 81, hydraulic rods 62, and grouting needles 65. The steel frame 81 and the hydraulic rods 62 are connected by three electric leveling screws 61. By adjusting the electric leveling screws, the grouting needles 65 are kept perpendicular to the construction surface. The four corners of the steel frame 81 are equipped with pulleys 83, which slide in cooperation with the slide rails 82 on the top surface of the vehicle body, allowing the steel frame 81 to move back and forth along the slide rails and achieve positioning and locking. The grouting needles 65 are inserted into the bottom of the grouting plate 64, and the grouting plate 64 is connected to the hydraulic rods 62 through a pressure sensor 63. The drive system is used to drive the grouting needle tube 65 to penetrate and lift, and the lifting speed v can be adjusted; A metering control system and an intelligent control system are used to control the grouting flow rate and link it with the lifting speed v to keep the grouting volume q per unit depth within a set range. The intelligent control system includes a data acquisition module, a parameter identification module, a control decision module, and an execution module. The control decision module calculates the grouting volume q per unit depth in real time based on a parameter prediction model formed by a preset threshold curve, a rule base, or historical construction data, and performs closed-loop adjustment of the grouting flow rate Q and the lifting speed v.

[0033] The mixing system includes a mixing cylinder 41, a mixing propeller 43, a pressurizing device 51, and a cement slurry conduit 44. The bottom of the mixing cylinder 41 is provided with a discharge valve 42. After the qualified cement slurry is discharged through the discharge valve 42, it is pressurized by the pressurizing device 51 and then transported to the grouting plate 64 along the cement slurry conduit 44, and injected into the underground roadbed through the grouting needle tube.

[0034] The grouting plate 64 is a cuboid with a length and width of approximately 1.5m and a height of approximately 0.2±0.05m. The upper center of the grouting plate is connected to a pressure sensor 63, and a grout inlet 66 is located at the upper edge and connected to a guide tube 52. A laser locator 67 is located at the lower center of the grouting plate 64 to ensure the grouting point is positioned, and grouting needles 65 are located at the four lower corners of the grouting plate 64.

[0035] The grouting needle tube 65 is a hollow tube with a pointed lower end. The grouting needle tube 65 is composed of several tubes 65a with a length of 0.5m connected by threads. Its overall length and inner diameter are adjustable. The outer wall of the tube is provided with length graduations to facilitate real-time observation and control of the insertion depth.

[0036] The grouting needle tube 65 includes a tube body 65a, and a one-way baffle 65c is provided at the lower end of the tube body 65a. The one-way baffle 65c is bolted to the tube body. When the grouting needle tube penetrates downward into the roadbed, under the upward reaction force of the roadbed, the one-way baffle 65c fits tightly with the lower end of the tube body, sealing the grout outlet. When the grouting needle tube 65 is lifted upward, the one-way baffle 65c rotates around the hinge point under its own weight, causing the lower end of the tube body 65a to open automatically, thereby realizing the opening and sealing of the grouting channel.

[0037] like Figure 1 The present invention also provides a wind-blown sand composite roadbed structure, comprising, from bottom to top, a lower roadbed layer, a group of cement-reinforced columns disposed within the lower roadbed layer, a geogrid 1 laid on the top surface of the lower roadbed with its mesh openings embedded and the protruding sections of the cement columns embedded therein, and an upper roadbed / reinforcement layer disposed on the geogrid 1. The cement-reinforced columns 2 can be arranged in a grid pattern or a staggered pattern, and can be densely arranged in the transition zone between the wheel track and the shoulder to meet the stress difference.

[0038] The features and parameters of this invention are defined as follows: Subgrade layer: Located above the roadbed, the subgrade layer of the roadbed bears the main impact of vehicle load diffusion. It is formed by layering and compacting aeolian sand.

[0039] Reinforcement depth hx: The effective reinforcement depth of the cement column from the top of the subgrade downwards, determined by the target bearing capacity or deformation control index.

[0040] Column diameter D: The equivalent diameter formed by the cement column solidification within the subgrade.

[0041] Lifting speed v: The speed at which the grouting needle is lifted vertically during the grouting process.

[0042] Grouting flow rate Q: The volumetric flow rate of grout injected into the grouting needle per unit time.

[0043] Grouting volume per unit depth q: The volume of grout injected per unit lifting length, which can be calculated from the grouting flow rate Q and the lifting speed v, satisfying q=Q / v (after unit conversion, it can be obtained as L / m or m). 3 / m).

[0044] Protrusion height Δh: The height of the column top above the top surface of the subgrade, used to allow the protruding section of the column top to penetrate the geogrid mesh and form a fixed structure.

[0045] Encryption spacing Sw, conventional spacing So: respectively corresponding to the column spacing in the wheel belt / shoulder transition area and other areas, satisfying Sw < So.

[0046] Compaction degree Ki: the measured compaction degree of the lower roadbed layer at the i-th representative point.

[0047] Penetration pressure curve P(h): the curve formed by the penetration force or cylinder pressure of the grouting needle pipe varying with the depth h when it penetrates into the lower roadbed, used to characterize the compaction state in different depth ranges of the lower roadbed.

[0048] Discrete depth point hj: the discrete depth position selected during the sampling and fitting of the penetration pressure curve.

[0049] Pressure threshold curve Pmin(h): the minimum allowable pressure curve corresponding to different depths of the grouting needle pipe when the target compaction degree condition is met, used to determine whether to allow the opening of the slurry outlet valve to implement pressure grouting.

[0050] αj, βj: the fitting intercept and fitting slope obtained when establishing the relationship between the compaction degree Ki and the penetration pressure P(hj) at the discrete depth point hj.

[0051] The present invention provides the following specific embodiments: (1) Foundation treatment and formation of the lower roadbed: After leveling the foundation surface, aeolian sand is used for layered paving and compacted to form the lower roadbed layer; the single-layer paving thickness can be 20 - 30 cm. The compaction can be carried out by dry compaction, vibratory compaction or other compaction methods that meet the engineering requirements.

[0052] (2) Lofting and parameter determination: Determine the cement column reinforcement depth hx according to the road structure design and bearing / deformation control requirements; determine the column diameter D, the point layout form and spacing. The plane layout is preferably grid-shaped or plum blossom-shaped; moderate densification is carried out in the wheel belt and shoulder transition area to form a differential layout of S < So. w Different layout with < So.

[0053] (3) Composition of the high-performance slurry: The high-performance slurry includes cement, mineral admixtures and additives; the mineral admixtures may include one or more of fly ash, slag powder, steel slag micropowder, desulfurized gypsum, tailing micropowder; the additives may include one or more of water reducers, micro-expansion components and anti-cracking fibers to improve the pumpability, early strength, volume stability and anti-cracking performance of the slurry.

[0054] (4) Method for determining the proportion of the high-performance slurry: The mix proportion of high-performance grout can be determined by a combination of indoor trial mixing, performance evaluation and field trial injection. That is, based on the project's requirements for grout pumpability, flow stability, early strength, column integrity and volume stability, cement, mineral admixtures and additives are selected for mix proportion optimization, and the grout mix proportion suitable for the current construction conditions is determined by combining test results and field adaptability feedback.

[0055] (5) Grouting to form a column: The determined high-performance grout is prepared by a mixing and supply device and then transported to the grouting needle. At the layout point, the needle is driven to penetrate to the reinforcement depth hx, the grout outlet valve is opened for pressure grouting and the needle is lifted simultaneously. By linking and controlling the lifting speed v and the grouting flow rate Q, the grouting amount q per unit depth is kept within the set range, thereby forming a continuous and uniform cement column reinforcement in the lower subgrade.

[0056] (6) Intelligent access control and process control: Before grouting and column formation, the compaction degree of the subgrade is tested. Grouting entry is only allowed after the compaction degree reaches a set threshold. To establish the correspondence between compaction degree and penetration pressure, in this embodiment, eight representative points are selected to test the compaction degree Ki of the subgrade, and the penetration pressure P(h) at different depths is collected simultaneously during the grouting needle penetration process. The corresponding data of compaction degree and penetration pressure are shown in Table 1.

[0057] Table 1 shows the data corresponding to point compaction degree and penetration pressure at different depths.

[0058] At discrete depth point h j At this point, the compaction degree Ki and the penetration pressure P(h) are related. j Linear fitting was performed on each side, and the following fitting relationship was established: P(h j )=α j +βj·Ki Where, α j For depth h j The fitting intercept at β j For depth h j The fitting slope at h = 0.2m, 0.4m, 0.6m, and 0.8m. For this embodiment, the following results were obtained at h = 0.2m, 0.4m, 0.6m, and 0.8m: P(0.2) = -5.993 + 8.401·Ki P(0.4) = -6.346 + 8.955·Ki P(0.6) = -6.616 + 9.314·Ki P(0.8) = -6.929 + 9.697·Ki The correlation coefficient R of the above fitting equation2 The values ​​are 0.979, 0.982, 0.983, and 0.984, respectively, indicating that the compaction degree Ki and the penetration pressure P(h) have a good linear correlation at each discrete depth point.

[0059] In this embodiment, the target compaction degree K0 = 0.950 is used to determine the pressure threshold curve Pmin(h). In this embodiment, the pressure threshold corresponding to each discrete depth point is: Pmin(0.2) = 1.955 MPa Pmin(0.4) = 2.128 MPa Pmin(0.6) = 2.199 MPa Pmin(0.8) = 2.250 MPa Therefore, the penetration pressure curve P(h) is collected in real time at the actual grouting point. When the real-time penetration pressure P(h) at the corresponding depth is not lower than the pressure threshold Pmin(h), the control system allows the grout outlet valve to be opened to implement pressure grouting; otherwise, the control system keeps the grout outlet valve closed and prompts to continue compaction or adjust the process parameters, thereby realizing the access control of the foundation state before column formation and the consistency control of process quality.

[0060] For ease of engineering application, the pressure threshold curve Pmin(h) can also be approximated as follows within the range of h = 0.2 to 0.8 m: Pmin(h) = 1.894 + 0.478·h Furthermore, after the access conditions are met and the grout outlet valve is opened, the control system calculates the grouting volume q per unit depth based on the real-time collected grouting flow rate Q, lifting speed v, and penetration pressure P(h), satisfying q=Q / v, and adjusts the grouting flow rate and lifting speed in conjunction with the working parameters to maintain the continuity and stability of the grouting process.

[0061] (7) Column top protrusion and leveling: When approaching the top surface of the lower subgrade, the grouting and lifting are adjusted to form a protruding section at the top of the column that is higher than the top surface of the lower subgrade, with a protrusion height of Δh. The surface of the lower subgrade is then leveled as necessary to ensure the flatness and positioning of the grid installation.

[0062] (8) Maintenance steps: The formed cement column solidification is sealed and moisturized by covering it with moisturizing material and spraying or sprinkling water until the cement column solidification reaches the preset early strength required for laying the geogrid; the preset early strength can be determined by the strength of the specimen under the same conditions or the field penetration resistance and rebound index reaching a set threshold.

[0063] (9) Laying geogrid and forming a fixed connection: Geogrid is laid on the top surface of the subgrade, allowing the protruding section of the cement column to pass through and fall within the geogrid mesh. Through the mechanical interlocking between the mesh and the outside of the column and the positioning restriction of the protruding section at the top of the column, the pore embedment connection is achieved.

[0064] (10) Construction of the superstructure: The upper subgrade, reinforcement layer and other subgrade structural layers are constructed on the geogrid to form a composite stress system composed of compacted aeolian sand layer, cement column reinforced solid column group and upper geogrid.

[0065] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, alterations, alterations, or substitutions made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A resource-based intelligent grouting construction method for aeolian sand composite roadbed, characterized in that, Includes the following steps: Step 1: Level and treat the foundation surface; Step 2: Use aeolian sand as filler to spread and compact the embankment and subgrade in layers, so that the aeolian sand forms a compacted layer that meets the construction requirements; Step 3: Mark out the grouting points on the lower subgrade and determine the reinforcement depth hx, column diameter D, and spacing S of the grouting columns. Step 4: Drive the grouting needle at each grouting point to penetrate from the top surface of the lower subgrade to the reinforcement depth hx, input cement grout into the grouting needle and perform pressure grouting during penetration or lifting, while controlling the lifting speed v and grouting flow rate of the grouting needle to keep the grouting amount q per unit depth within the set range, thereby forming a cement column reinforcement body with a column diameter of D in the lower subgrade. Step 5: Control the top elevation of the cement column reinforcement so that the top of the column forms a protruding section relative to the top surface of the lower subgrade. After the grouting is completed, seal and moisturize the cement column reinforcement until it reaches the preset strength. Step 6: Lay geogrid on the top surface of the lower subgrade, so that the protruding section of the cement column reinforced body passes through and falls into the mesh of the geogrid, thereby forming a pore-embedded connection between the geogrid and the cement column reinforced body. Step 7: Continue construction of the upper subgrade and pavement structure on the geogrid.

2. The intelligent grouting construction method for aeolian sand composite roadbed according to claim 1, characterized in that, The reinforcement depth hx is the effective reinforcement depth of the grouting column from the top of the lower subgrade downwards.

3. The intelligent grouting construction method for aeolian sand composite roadbed according to claim 1, characterized in that, The aeolian sand filler is laid in layers, with each layer being 30cm thick. After laying, it is compacted to form a compacted layer.

4. The intelligent grouting construction method for aeolian sand composite roadbed according to claim 1, characterized in that, Cement grout includes cement, mineral admixtures, and additives.

5. The intelligent grouting construction method for aeolian sand composite roadbed according to claim 1, characterized in that, Step 4, prior to construction, also includes determining the grouting construction access conditions by testing the compaction degree of the subgrade layer, including: Representative points were selected to test the compaction degree Ki of the lower roadbed, and the penetration pressure variation curve P(h) at different depths was collected simultaneously during the grouting needle penetration process; a fitting relationship between compaction degree Ki and penetration pressure P(hj) was established at discrete depth points hj: P(hj)=αj+βj·Ki; Using the penetration pressure corresponding to the target compaction degree K0 as the entry threshold, the pressure threshold curve Pmin(h) is obtained; the penetration pressure is collected in real time at the grouting point, and when the penetration pressure is not lower than the pressure threshold of the corresponding depth, the grout outlet valve is opened to perform pressure grouting.

6. The intelligent grouting construction method for aeolian sand composite roadbed according to claim 5, characterized in that, In step 4, during the pressure grouting process, adaptive control is adopted, including: based on the real-time collected compaction degree Ki, penetration pressure variation curve P(h) with depth, grouting flow rate Q, lifting speed v, and grouting volume per unit depth q, the current construction conditions are identified online, and the grouting flow rate, grouting pressure, and lifting speed are dynamically adjusted so that the grouting volume per unit depth q and grouting pressure remain constant or within the set fluctuation range.

7. The intelligent grouting construction method for aeolian sand composite roadbed according to claim 1, characterized in that, Grouting points are arranged in a grid or quincunx pattern to form a group of cement-reinforced columns.

8. A resource-based intelligent grouting construction device for aeolian sand composite roadbed, employing the resource-based intelligent grouting construction method for aeolian sand composite roadbed as described in any one of claims 1-7, characterized in that, include: Vehicle body, control system, power system, grouting system, and mixing system; The grouting system includes a steel frame (81), hydraulic rods (62), and grouting needles (65). The steel frame (81) is connected to the hydraulic rods (62). The steel frame (81) is installed on the vehicle body. The output end of the hydraulic rods (62) is connected to the grouting needles (65). The grouting needle tube (65) includes a tube body (65a), and a one-way baffle (65c) is provided at the lower end of the tube body (65a). The one-way baffle (65c) and the tube body (65a) are bolted together. When the grouting needle tube (65) penetrates the roadbed downwards, under the action of the upward reaction force of the roadbed, the one-way baffle (65c) fits tightly with the lower end of the tube body and seals the grout outlet. When the grouting needle tube (65) is lifted upwards, the one-way baffle (65c) rotates around the hinge point under its own weight, so that the lower end of the tube body (65a) opens.

9. A wind-blown sand composite roadbed structure, based on the resource-based intelligent grouting construction method for wind-blown sand composite roadbed according to any one of claims 1-7, characterized in that, It includes a subgrade, a group of cement-reinforced columns installed inside the subgrade, a geogrid laid on the top surface of the subgrade and embedded with the protruding sections of the cement columns, and an upper subgrade installed on the geogrid.

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