Cement-soil mixing pile digital construction system and method

Abstract

The application discloses a cement-soil mixing pile digital construction system and method, and belongs to the technical field of pile foundation construction digital control. The system comprises the following steps: obtaining stratum distribution data of a construction area and generating a three-dimensional geological model; in the drilling process of a drilling machine, a first drilling parameter set of a drill bit is collected in real time, and the working state of the drilling machine is dynamically adjusted in combination with the three-dimensional geological model; when the drill bit reaches a preset design pile bottom elevation, a grouting pump is started to spray cement slurry to the soil body, and a second drilling parameter set in the lifting process of the drill bit is collected in real time; the lifting speed of the drill bit and the grouting pressure are dynamically adjusted according to the second drilling parameter set and the three-dimensional geological model; after the drill bit is lifted to a preset design pile top elevation, the drilling machine is controlled to perform multiple reciprocating mixing operations, and a third drilling parameter set is collected in each reciprocating mixing process; and the pile forming uniformity is judged according to the multiple third drilling parameter sets. The scheme improves the stratum adaptability and pile forming quality control capability in the construction process of the cement-soil mixing pile.

Description

Technical Field

[0001] This invention relates to the field of digital control technology for pile foundation construction, specifically to a digital construction system and method for cement-soil mixing piles. Background Technology

[0002] During the construction of cement-soil mixing piles, the soil properties encountered by the drill bit at different depths vary significantly. Changes in soil strength, permeability, and pore structure directly affect drilling resistance, cement slurry diffusion range, and the energy input required for mixing. Existing construction methods typically rely on discrete borehole data from geological survey reports, setting uniform drilling speed, grouting pressure, and mixing times for the entire pile length. These parameters remain largely unchanged during construction. However, when the actual geological distribution deviates from the survey data or when the geological properties vary considerably along the depth direction, the fixed-parameter construction method struggles to adapt to the differences in soil characteristics at different depths, easily leading to insufficient cement-soil mixing or uneven cement slurry distribution in localized areas.

[0003] In the pile quality control stage, existing technologies mainly rely on post-construction core sampling and static load tests for inspection. These post-construction inspection methods can only sample and evaluate the constructed piles, failing to identify unevenly mixed depths during construction or to provide timely reinforcement for defective sections. While some construction methods record construction parameters, they only monitor and display single indicators such as drilling speed and grouting volume, lacking quantitative analysis methods to understand the relationship between parameter fluctuations and pile uniformity. Operators cannot determine whether the mixing quality at different depths within the pile meets requirements based on recorded data.

[0004] When there are soft-hard interfaces or localized hard interlayers in the strata, the resistance encountered by the drill bit varies significantly in different soil layers. If a fixed rotation speed and lifting speed are still used for reciprocating mixing, the drill bit will not cut the cement-soil mass enough in some depth ranges, while there will be excessive energy input in other ranges, resulting in significant differences in the uniformity of cement-soil at different depths of the pile. Existing construction methods lack construction control means to combine real-time collected drilling parameters with stratum spatial distribution information and to determine mixing control parameters separately for different depth ranges. Summary of the Invention

[0005] This invention provides a digital construction method for cement-soil mixing piles, aiming to solve the problems that fixed construction parameters cannot adapt to changes in geological conditions and that the uniformity of pile formation lacks quantitative judgment and targeted control methods during the construction process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a digital construction method for cement-soil mixing piles, which acquires geological distribution data of the construction area and generates a three-dimensional geological model; during the drilling process, the first set of drilling parameters of the drill bit is collected in real time, and the first working state of the drill bit is dynamically adjusted according to the first set of drilling parameters and the three-dimensional geological model; when the drill bit reaches the preset design pile bottom elevation, the grouting pump is started to spray cement slurry into the soil, and the second set of drilling parameters during the drill bit lifting process is collected in real time; the lifting speed of the drill bit and the grouting pressure of the grouting pump are dynamically adjusted according to the second set of drilling parameters and the three-dimensional geological model; after the drill bit is lifted to the preset design pile top elevation, the drill bit is controlled to perform multiple reciprocating mixing operations, and a third set of drilling parameters is collected during each reciprocating mixing process; the uniformity of the current cement-soil mixing pile is determined according to the multiple third sets of drilling parameters collected during the multiple reciprocating mixing processes; if the uniformity of the pile does not meet the preset standard, the drill bit rotation speed and lifting speed for the next reciprocating mixing are adjusted according to the currently collected third set of drilling parameters and the three-dimensional geological model. This method integrates a three-dimensional geological model with the real-time operating parameters of the drilling rig, enabling dynamic adjustment of the drilling, grouting, and mixing processes, thereby improving the uniformity of cement-soil mixing pile formation and construction quality.

[0007] As a technical solution of this invention, when acquiring stratigraphic distribution data of the construction area and generating a three-dimensional geological model, multiple exploration points can be set up within the construction area according to a preset grid spacing. Continuous stratigraphic penetration resistance data are obtained at each exploration point through static cone penetration tests. Based on the stratigraphic penetration resistance data, the soil interface depth at each exploration point is divided, and the soil property category of each soil layer is determined. The soil interface depth and soil property category of all exploration points are input into a three-dimensional interpolation engine to generate an initial three-dimensional geological body reflecting the stratigraphic distribution of the construction area. Using existing geological borehole columnar sections within the construction area as rigid constraints, the local boundaries of the initial three-dimensional geological body are corrected to obtain the three-dimensional geological model. This method can improve the accuracy of the three-dimensional geological model in representing the actual strata and provide a reliable basis for subsequent adjustments to construction parameters.

[0008] As a technical solution of the present invention, during the drilling process, a first torque value, a first drilling pressure value, and a first drilling rate of the drill bit are collected at a first sampling frequency to form a first drilling parameter set; the predicted soil strength value at the current drill bit position is extracted from the three-dimensional geological model, and the theoretical drilling rate range of the drill bit is calculated based on the predicted soil strength value; the first drilling rate is compared with the theoretical drilling rate range, and when the first drilling rate exceeds the theoretical drilling rate range, the output speed of the drill bit's power head and the pressure of the feed cylinder are adjusted to bring the first drilling rate back to within the theoretical drilling rate range. This closed-loop adjustment method enables the drill bit to maintain a reasonable drilling state in different formations, reducing abnormal drilling efficiency and the risk of stuck drill bit.

[0009] As a technical solution of the present invention, when the drill bit reaches the preset design pile bottom elevation, the grouting pump is triggered to start and inject cement grout into the soil at a first grouting pressure. Simultaneously, the drilling rig is switched to lifting mode. During the drill bit lifting process, the second torque value, second drilling pressure value, lifting rate, and real-time grouting pressure value of the grouting pump are collected at a second sampling frequency to form a second drilling parameter set. While collecting the second drilling parameter set, the verticality deviation value of the drill bit is monitored in real time. When the verticality deviation value exceeds a preset deviation threshold, the mast inclination angle of the drilling rig is adjusted. This allows for simultaneous control of the pile verticality during the grouting lifting stage, reducing the risk of pile integrity defects due to deflection.

[0010] As a technical solution of the present invention, when dynamically adjusting the drill bit lifting speed and the grouting pump pressure according to the second drilling parameter set and the three-dimensional geological model, the soil permeability coefficient and soil porosity at the current drill bit position are extracted from the three-dimensional geological model; the theoretical cement slurry diffusion rate at the current soil position is calculated based on the soil permeability coefficient and soil porosity; the real-time grouting pressure value is adjusted to a grouting pressure value that matches the theoretical cement slurry diffusion rate; and the drill bit lifting speed is adjusted according to the second torque value and the second drilling pressure value. This method matches the grouting pressure and lifting speed with the soil characteristics, which is beneficial to improving the uniformity of cement slurry distribution within the pile body.

[0011] As a technical solution of this invention, after the drill bit is raised to the preset design pile top elevation, the power head is controlled to reverse, driving the drill bit to sink from the pile top elevation to the pile bottom elevation at a first sinking rate, and cutting the cement-soil body at a first mixing speed during the sinking process; when the drill bit reaches the pile bottom elevation again, the power head is controlled to rotate forward, driving the drill bit to lift from the pile bottom elevation to the pile top elevation at a first lifting rate, and cutting the cement-soil body a second time at a second mixing speed during the lifting process; throughout the entire sinking and lifting process of the drill bit, the third torque value, third drilling pressure value, actual sinking rate, and actual lifting rate of the drill bit are continuously collected at a third sampling frequency as a third drilling parameter set. Through repeated cutting and mixing, the uniformity of cement-soil mixing can be improved.

[0012] As a technical solution of this invention, when judging the uniformity of pile formation based on multiple sets of third drilling parameters collected during repeated mixing processes, the multiple sets of third drilling parameters are divided according to depth intervals to obtain multiple sets of torque values ​​and drilling pressure values ​​corresponding to each depth interval. The torque variation coefficient and drilling pressure variation coefficient of the multiple sets of torque values ​​and drilling pressure values ​​within each depth interval are calculated. The torque variation coefficient and drilling pressure variation coefficient of each depth interval are compared with their respective corresponding variation coefficient thresholds. When the torque variation coefficient or drilling pressure variation coefficient of any depth interval exceeds the corresponding variation coefficient threshold, that depth interval is determined to be a non-uniform interval. The number of all non-uniform intervals is counted. When the number of non-uniform intervals exceeds a preset threshold, the uniformity of the current cement-soil mixing pile is determined to have not reached the preset standard. This judgment method can quantitatively evaluate the mixing uniformity of different depth intervals, providing a basis for targeted supplementary mixing.

[0013] As a technical solution of this invention, when the uniformity of pile formation is determined to be below a preset standard, the actual soil layer categories corresponding to the depth ranges of all determined non-uniform intervals are obtained, and the optimal mixing energy input value corresponding to each actual soil layer category is extracted from the three-dimensional geological model. Based on the optimal mixing energy input value, the target rotation speed and target lifting speed value for each non-uniform interval during the next reciprocating mixing are calculated. During the next reciprocating mixing, when passing through the non-uniform interval, the drill bit rotation speed is adjusted to the corresponding target rotation speed value, and the lifting speed or sinking speed when passing through the non-uniform interval is adjusted to the corresponding target lifting speed value. This method performs point-to-point parameter adjustment for non-uniform intervals, reduces the unnecessary energy consumption caused by uniform adjustment of the entire pile, and improves the local uniformity of pile formation.

[0014] As a technical solution of the present invention, during the entire process of drill bit descent and elution, when the third torque value exceeds the upper limit threshold of torque corresponding to the current depth range, the vertical movement of the drill bit is paused and the first or second stirring speed is increased until the third torque value falls back below the upper limit threshold of torque. This can avoid equipment damage or uneven stirring caused by excessive torque.

[0015] This invention also provides a digital construction system for cement-soil mixing piles, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of the aforementioned digital construction method for cement-soil mixing piles. The system has real-time data acquisition, model analysis, and automatic control capabilities, which can improve the consistency of the construction process and the quality of pile formation.

[0016] The technical effects and advantages provided by the present invention in the above technical solution are as follows: The construction of the three-dimensional geological model integrates the penetration resistance data of the strata obtained from static cone penetration tests with the rigid constraints of existing geological borehole columnar sections, enabling it to reflect the physical and mechanical characteristics of soil layers at various depths in the construction area in a continuous spatial distribution. During the drilling phase, the first set of drilling parameters acquired in real time is compared with the predicted soil strength value at the current drill bit position in the three-dimensional geological model. When the actual drilling rate deviates from the theoretical drilling rate range, the power head output speed and feed cylinder pressure are automatically adjusted to match the drilling process with the drillability of the current soil layer. This closed-loop adjustment method based on the deviation between the geological model's predicted values ​​and real-time measurements avoids the problems of decreased drilling efficiency or drill bit overload that may occur at the interface between soft and hard strata when fixed drilling parameters are used.

[0017] During the shotcrete lifting stage, the soil permeability coefficient and void ratio at the current depth are extracted from the 3D geological model to calculate the theoretical cement grout diffusion rate. Based on this, the real-time shotcrete pressure of the shotcrete pump is adjusted, and the lifting rate is adjusted according to real-time torque and drilling pressure data. The linkage adjustment of shotcrete pressure and lifting speed allows the amount of cement grout injected to follow the changes in the permeability characteristics of soil layers at different depths, reducing local enrichment or loss of cement grout caused by mismatch between shotcrete parameters and soil conditions.

[0018] Regarding the assessment of pile uniformity, the coefficient of variation (COP) of the third set of drilling parameters collected during multiple reciprocating mixing processes is calculated using depth intervals as units, yielding the torque COP and drill pressure COP. The fluctuation amplitude of torque and drill pressure during multiple mixing processes within the same depth interval reflects the degree of uniformity in the cutting of the cement-soil mass within that interval. Depth intervals with COPs exceeding the threshold are considered unevenly mixed intervals. This assessment method quantitatively evaluates the mixing uniformity of each depth interval using mechanical parameters collected in real time during construction, eliminating the need for destructive sampling and testing after pile completion, and enabling the identification of quality problem sections during the construction phase.

[0019] For depth ranges identified as non-uniform, the corresponding soil layer type and optimal mixing energy input value are extracted from the 3D geological model. The target rotation speed and target lifting speed values ​​for the next reciprocating mixing cycle through these ranges are calculated, and the adjusted parameters are applied when passing through non-uniform ranges. This method of differentiated parameter adjustment for different depth ranges matches the mixing energy input to the mixing difficulty of local soil layers. By repeatedly supplementing mixing in non-uniform ranges until the parameter variation coefficient falls below the threshold, targeted repair of local defects in the pile is achieved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a flowchart of the digital construction method for cement-soil mixing piles; Figure 2 This is a flowchart of the adaptive adjustment method for drilling rig parameters; Figure 3 It is a curve comparing the first drilling parameters of the drilling rig with the theoretical drilling rate range; Figure 4 It is the coefficient of variation of the parameters of repeated mixing of cement-soil mixing piles and the curve of drill bit speed and target lifting speed. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See Figure 1 This invention provides a digital construction system and method for cement-soil mixing piles. It acquires geological distribution data of the construction area and generates a three-dimensional geological model based on this data. During drilling, a first set of drilling parameters from the drill bit is collected in real time, and the first working state of the drill bit is dynamically adjusted based on the first set of drilling parameters and the three-dimensional geological model. When the drill bit reaches the preset design pile bottom elevation, a grouting pump is started to inject cement slurry into the soil, and a second set of drilling parameters is collected in real time during the drill bit lifting process. Based on the second set of drilling parameters and the three-dimensional geological model, the lifting speed of the drill bit and the grouting pressure of the grouting pump are dynamically adjusted. After the drill bit is lifted to the preset design pile top elevation, the drill bit is controlled to perform multiple reciprocating mixing operations, and a third set of drilling parameters is collected during each reciprocating mixing process. Based on the multiple sets of third drilling parameters collected during the multiple reciprocating mixing processes, the uniformity of the current cement-soil mixing pile is determined. If the uniformity of pile formation does not meet the preset standard, the drill bit rotation speed and lifting speed for the next reciprocating stirring will be adjusted according to the currently collected third drilling parameter set and the three-dimensional geological model.

[0024] In practice, multiple exploration points are set up within the construction area at a preset grid spacing. The preset grid spacing is determined based on the planar dimensions of the construction area and the degree of horizontal variation in the strata, which is obtained from previous geological survey data of the construction area. At each exploration point, a static cone penetration test probe is vertically driven into the soil at a constant rate, continuously collecting cone tip resistance and sidewall friction. The cone tip resistance and sidewall friction are recorded as data points at 0.1-meter depth intervals, forming continuous data on stratum penetration resistance. The static cone penetration test is set at a penetration rate of 20 mm / s. The static cone penetration test is terminated when the probe reaches 5 meters below the estimated deepest soil interface in the construction area or reaches the maximum penetration capacity of the static cone penetration test equipment.

[0025] In practice, the soil interface depth at each exploration point is determined based on the ground penetration resistance data. For each exploration point, the cone tip resistance variation rate is calculated along the depth direction for the ground penetration resistance data. When the absolute value of the cone tip resistance variation rate exceeds a preset variation rate threshold, the depth between adjacent depth data points is defined as the soil interface depth. Optionally, the preset variation rate threshold is determined by multiplying the instrument measurement noise standard deviation of the ground penetration resistance data by 3. Simultaneously, the ground penetration resistance data at each exploration point is divided into depth segments, each located between two adjacent soil interface depths. The average cone tip resistance, average sidewall friction resistance, and average friction ratio are extracted from each depth segment. The average friction ratio is calculated by dividing the average sidewall friction resistance by the average cone tip resistance. The average cone tip resistance, average sidewall friction resistance, and average friction ratio for each depth segment are compared with a preset soil property classification table to determine the corresponding soil property category for each depth segment. The preset soil property classification table includes the cone tip resistance range, sidewall friction range, and friction ratio range for each of the following soil types: clay, silty clay, silt, sand, and gravelly soil.

[0026] In its implementation, the 3D interpolation engine comprises a data preprocessing module, a spatial interpolation module, and a geological body construction module. The data preprocessing module takes as input the soil interface depths and soil property types of all exploration points and outputs a set of spatially discrete points arranged in soil layer order. For each exploration point, the data preprocessing module combines each soil interface depth with planar coordinates to form spatially discrete points of the soil interface; it also appends the soil property type code corresponding to each soil interface depth to these spatially discrete points. The spatial interpolation module takes as input the set of spatially discrete points of the soil interface and outputs the interpolated soil interface depths on regular grid nodes within the construction area. The spatial interpolation module uses the Kriging interpolation method, performing interpolation on the spatially discrete point set corresponding to each soil interface separately. The geological body construction module takes as input the interpolated soil interface depths and soil property type codes on regular grid nodes and outputs the initial 3D geological body. The geological body construction module encloses the regular grid nodes between adjacent soil layer interfaces into spatial elements in the order of shallow to deep soil layer interface depth, and assigns a soil property category code to each spatial element corresponding to the depth segment.

[0027] In practice, existing geological borehole columnar sections within the construction area are used as hard constraints. These sections include borehole planar coordinates, the depths of soil interfaces at each borehole location, and the soil property categories at that location. Initial soil interface depths are extracted from the grid nodes in the initial 3D geological body that share the same planar coordinates as each borehole columnar section. These initial soil interface depths are then compared to the borehole soil interface depths in the geological borehole columnar sections. If the absolute value of the difference between the initial and borehole soil interface depths is greater than 0.1 meters, the corresponding planar coordinate location in the geological borehole columnar section is designated as a hard constraint node. All hard constraint nodes are added to the input point set of the spatial interpolation module, and the kriging interpolation method in the spatial interpolation module is set to a constrained kriging interpolation method. The constrained kriging interpolation method incorporates precise interpolation conditions for the hard constraint nodes when solving for the weight coefficients, ensuring that the interpolation results at the hard constraint nodes are completely consistent with the borehole soil interface depths in the geological borehole columnar sections. The spatial interpolation module re-executes the interpolation, and the geological body construction module generates a corrected three-dimensional geological model based on the interface depths of each soil layer after re-interpolation.

[0028] In specific implementation, please refer to Figure 2During drilling, the first torque value, first drilling pressure value, and first drilling rate of the drill bit are collected at a first sampling frequency to form a first drilling parameter set. The first sampling frequency is set to 10 Hz. The first torque value is collected by a torque sensor installed on the output shaft of the drill rig's power head, the first drilling pressure value is collected by a pressure sensor installed on the hydraulic circuit of the feed cylinder, and the first drilling rate is obtained by differential calculation of the vertical displacement of the drill bit by a stroke sensor installed on the drill rig mast at the first sampling frequency. The data collected by the torque sensor, pressure sensor, and stroke sensor are synchronously aggregated by the drill rig control system and aligned according to timestamps to form the first drilling parameter set.

[0029] In practice, the current depth of the drill bit is calculated based on the mast tilt sensor, stroke sensor, and the initial position of the drill bit. The initial position of the drill bit is the depth it was at before drilling began, recorded by the drilling rig control system. The current depth of the drill bit is equal to the initial position plus the product of the vertical displacement of the drill bit recorded by the stroke sensor and the cosine of the mast tilt angle. The current depth of the drill bit is combined with the planar coordinates of the construction area to form the current drill bit position query coordinates. Based on the current drill bit position query coordinates, the predicted soil strength value at the current drill bit position is extracted from the 3D geological model.

[0030] In practice, the theoretical drilling rate range is calculated based on the predicted soil strength value, using the following formula:

[0031] in, This represents the lower limit of the theoretical drilling rate range, expressed in meters per minute. This represents the upper limit of the theoretical drilling rate range, expressed in meters per minute. The predicted soil strength value at the current drill bit location is extracted from the three-dimensional geological model, in megapascals (MPa). The coefficient for calculating the lower limit of drilling rate is expressed in megapascal-meters per minute. The coefficient is used to calculate the upper limit of the drilling rate, and the unit is megapascal-meter / minute.

[0032] The following method was used to determine the strength of the soil layer: A calibration test was conducted in a representative soil layer of the construction area. The output speed of the drilling rig's power head was set to 80% of the rated speed, and the feed cylinder pressure was set to 80% of the rated pressure. The drilling rate and the corresponding soil layer strength value were recorded. The drilling rate was multiplied by the corresponding soil layer strength value to obtain the final strength value. . The following method was used to determine the strength of the soil layer: A calibration test was conducted in a representative soil layer of the construction area. The output speed of the drilling rig's power head was set to the rated speed, and the feed cylinder pressure was set to the rated pressure. The drilling rate and the corresponding soil layer strength value were recorded. The drilling rate was then multiplied by the corresponding soil layer strength value to obtain the final strength value. When the calibration test covers multiple representative soil layers, Take the average value of the calibration results for all representative soil layers. Take the average value of the calibration results for all representative soil layers.

[0033] In practice, the first drilling rate is compared with the theoretical drilling rate range. If the first drilling rate is greater than the upper limit of the theoretical drilling rate range, the drill bit drilling rate is determined to be too fast, and the drilling rig control system reduces the power head output speed and feed cylinder pressure. If the first drilling rate is less than the lower limit of the theoretical drilling rate range, the drill bit drilling rate is determined to be too slow, and the drilling rig control system increases the power head output speed and feed cylinder pressure. The adjustment amount of the power head output speed is calculated by multiplying the absolute value of the difference between the first drilling rate and the upper or lower limit of the theoretical drilling rate range by a first proportional coefficient, and the adjustment amount of the feed cylinder pressure is calculated by multiplying the absolute value of the difference between the first drilling rate and the upper or lower limit of the theoretical drilling rate range by a second proportional coefficient. Both the first and second proportional coefficients are obtained by calibrating the response characteristics of the drilling rig hydraulic system. The adjusted power head output speed and feed cylinder pressure are sent by the drilling rig control system to the power head motor and the electro-hydraulic proportional valve of the feed cylinder, so that the first drilling rate returns to within the theoretical drilling rate range.

[0034] See Figure 3 In the graph, the horizontal axis represents time in minutes, and the vertical axis represents numerical values. The first torque value divided by 100 and the first drill pressure value divided by 50 are displayed coaxially with the first drilling rate. All values ​​have been normalized. The blue solid line represents the first drilling rate, the red dashed line and the green dotted line represent the lower and upper limits of the theoretical drilling rate range calculated based on the predicted soil strength values ​​in the 3D geological model, respectively. The orange dotted line represents the first torque value / 100, and the purple solid line represents the first drill pressure value / 50. The first drilling rate fluctuates within the theoretical drilling rate range, showing a trend of first rising and then falling, reaching a peak at approximately 5 minutes, and then slowly decreasing to around 15 minutes. At 15 minutes, the first drilling rate drops sharply to near the lower limit of the theoretical drilling rate range, and then gradually recovers. The trends of the first torque value / 100 and the first drill pressure value / 50 are relatively stable, fluctuating between 1.2 and 1.8, and are partially synchronized with the trend of the first drilling rate. Overall, the drilling rig control system dynamically adjusts the power head output speed and feed cylinder pressure by collecting and comparing the initial drilling rate with the theoretical drilling rate range in real time, thus maintaining the drilling rate within a reasonable range and ensuring the stability and safety of the drilling process. A rapid decrease in the drilling rate at 15 minutes may reflect the control system's response and adjustment to abnormal operating conditions.

[0035] In practice, when the drill bit reaches the preset design pile bottom elevation, the grouting pump is triggered to start and injects cement grout into the soil at the first grouting pressure. Simultaneously, the drilling rig is switched to lifting mode. The first grouting pressure is preset by the drilling rig control system before construction. This pressure is calculated based on the designed pile diameter of the cement-soil mixing pile, the water-cement ratio of the cement grout, and the pressure loss at the grouting pump outlet. The pressure loss at the grouting pump outlet is determined by the length of the grouting pipeline, the inner diameter of the grouting pipe, and the dynamic viscosity of the cement grout. After the grouting pump starts, the plunger pump outputs cement grout at the flow rate corresponding to the first grouting pressure. The cement grout is transported through the grouting pipeline to the drill bit nozzle and injected into the soil.

[0036] In practice, during the drill bit lifting process, the second torque value, second drilling pressure value, drill bit lifting rate, and real-time grouting pressure value of the grouting pump are collected at a second sampling frequency to form a second drilling parameter set. The second sampling frequency is set to 5 Hz. The second torque value is collected by a torque sensor installed on the drill rig's power head; the second drilling pressure value is collected by a tension sensor installed on the drill rig's lifting wire rope or lifting cylinder; the drill bit lifting rate is obtained by differential calculation of the drill bit's vertical displacement using a stroke sensor installed on the drill rig mast at the second sampling frequency; and the real-time grouting pressure value of the grouting pump is collected by a pressure transmitter installed on the grouting pipeline. The data collected by the torque sensor, tension sensor, stroke sensor, and pressure transmitter are synchronously aggregated through the drill rig control system and aligned according to timestamps to form the second drilling parameter set.

[0037] In practice, while acquiring the second set of drilling parameters, the verticality deviation of the drill bit is monitored in real time. The verticality deviation is measured in real time by a dual-axis tilt sensor mounted on the drilling rig mast. The dual-axis tilt sensor outputs the mast's forward / backward tilt angle and left / right tilt angle. The drilling rig control system calculates the verticality deviation value using a vector synthesis method based on these angles. The verticality deviation value is then compared with a preset deviation threshold, which is set to 0.5 degrees. This preset threshold is based on the angle limit corresponding to no more than 0.5% of the pile length in the allowable verticality deviation standard for cement-soil mixing piles. If the verticality deviation value exceeds the preset deviation threshold, the drilling rig control system controls the mast's verticality adjustment cylinder to adjust the mast's tilt angle until the verticality deviation value falls back below the preset deviation threshold.

[0038] In practice, the soil permeability coefficient and void ratio at the current drill bit position are extracted from the 3D geological model. The current drill bit position is calculated based on the initial drill bit position, the vertical displacement of the drill bit recorded by the travel sensor, and the mast inclination angle. The initial drill bit position is the depth at which the drill bit was located before drilling began. During the modeling process, the soil permeability coefficient and void ratio corresponding to each soil layer element are written as attribute information into the soil layer data. During extraction, the drilling rig control system queries the corresponding soil layer element based on the current drill bit position and reads the soil permeability coefficient and void ratio from the soil layer element attribute data.

[0039] In practical implementation, the theoretical cement slurry diffusion rate at the current soil layer location is calculated based on the soil layer permeability coefficient and void ratio. The calculation formula is as follows:

[0040] in, The theoretical cement slurry diffusion rate is expressed in meters per second. The soil permeability coefficient at the current drill bit location is extracted from the 3D geological model, in meters per second. The void ratio of the soil layer at the current drill bit location is extracted from the three-dimensional geological model and is dimensionless. is the sprayed grout diffusion matching coefficient, which is dimensionless.

[0041] The range of the shotcrete diffusion matching coefficient is determined according to the stratum type of the construction area as follows: when the stratum soil type is clay or silty clay, the shotcrete diffusion matching coefficient is 0.05 to 0.2; when the stratum soil type is silt or sand, the shotcrete diffusion matching coefficient is 0.2 to 0.5. The shotcrete diffusion matching coefficient is obtained as follows: during the on-site cement-soil mixing pile test pile construction, shotcrete diffusion calibration is performed on clay, silty clay, silt, and sand respectively. The rate of change of the radial diffusion radius of cement slurry in the corresponding soil layer with time is recorded, and the soil permeability coefficient and soil void ratio of the soil layer where the test pile is located are extracted. The shotcrete diffusion matching coefficient is calculated by multiplying the rate of change of the radial diffusion radius of cement slurry with time by the soil void ratio and then dividing by the soil permeability coefficient. The average value of the shotcrete diffusion matching coefficients obtained by back-calculating the test piles of the same soil type is taken, and the average value is written into the drilling rig control system according to the soil type.

[0042] In practice, the real-time grouting pressure is adjusted to match the theoretical cement slurry diffusion rate. The drilling rig control system establishes a mapping relationship between the real-time grouting pressure and the theoretical cement slurry diffusion rate, determined jointly by the grouting pump pressure-flow characteristic curve and on-site pile calibration data. When the real-time grouting pressure is less than the matching grouting pressure corresponding to the theoretical cement slurry diffusion rate, the drilling rig control system increases the output flow rate of the grouting pump hydraulic motor, thereby increasing the grouting pressure; conversely, when the real-time grouting pressure is greater than the matching grouting pressure corresponding to the theoretical cement slurry diffusion rate, the drilling rig control system decreases the output flow rate of the grouting pump hydraulic motor, thereby reducing the grouting pressure.

[0043] In practice, the drill bit lifting rate is adjusted simultaneously based on the second torque value and the second drill pressure value. The drilling rig control system compares the second torque value with the preset upper and lower torque thresholds corresponding to the current soil depth, and compares the second drill pressure value with the preset upper and lower drill pressure thresholds corresponding to the current soil depth. If the second torque value exceeds the preset upper torque threshold or the second drill pressure value exceeds the preset upper drill pressure threshold, the drill bit lifting rate is reduced; if the second torque value is lower than the preset lower torque threshold and the second drill pressure value is lower than the preset lower drill pressure threshold, the drill bit lifting rate is increased. The preset upper torque threshold, preset lower torque threshold, preset upper drill pressure threshold, and preset lower drill pressure threshold are obtained from the preset mixing parameter table based on the soil property category of the soil layer volume element in the three-dimensional geological model.

[0044] In practice, after the drill bit is raised to the preset design pile top elevation, the drilling rig control system controls the power head to reverse. The power head reversal signal is sent from the drilling rig control system to the power head frequency converter, which drives the power head motor to reverse. Driven by the power head reversal, the drill bit descends from the pile top elevation to the pile bottom elevation at a first sinking rate. The first sinking rate is preset by the construction plan and stored in the parameter table of the drilling rig control system. During the sinking process, the drill bit cuts the cement-soil at a first mixing speed, which is the output speed when the power head reverses. The first mixing speed is adjusted in a closed loop by the drilling rig control system based on the feedback of the power head motor speed.

[0045] Once the drill bit reaches the pile bottom elevation again, the drilling rig control system controls the power head to rotate forward. The forward rotation signal is sent from the drilling rig control system to the power head frequency converter, which drives the power head motor to rotate forward. Driven by the forward rotation of the power head, the drill bit is lifted from the pile bottom elevation to the pile top elevation at a first lifting rate. During the lifting process, the drill bit cuts the cement-soil a second time at a second mixing speed. The second mixing speed is the output speed of the power head during forward rotation, and it is adjusted in a closed loop by the drilling rig control system based on feedback from the power head motor speed.

[0046] In practice, throughout the entire process of drill bit descent and elution, a third torque value, a third drill pressure value, an actual descent rate, and an actual elution rate are continuously collected at a third sampling frequency to form the third drilling parameter set. The third sampling frequency is set to 5 Hz. The third torque value is collected by a torque sensor mounted on the power head output shaft. The third drill pressure value is collected by a combination of pressure sensors mounted on the drill rig's lifting cylinder and feed cylinder, and converted into an equivalent drill pressure value by the drill rig control system. The actual descent rate is obtained by differential calculation of the drill bit's vertical displacement using a stroke sensor mounted on the drill rig mast. The actual elution rate is also obtained by differential calculation of the drill bit's vertical displacement using a stroke sensor. The signals collected by the torque sensor, lifting cylinder pressure sensor, feed cylinder pressure sensor, and stroke sensor are synchronously aggregated by the drill rig control system and aligned according to timestamps to form the third drilling parameter set.

[0047] Multiple sets of third drilling parameters collected during repeated mixing processes are divided into depth intervals. The depth intervals are divided as follows: starting from the pile bottom elevation, the entire pile length is divided into multiple depth intervals at fixed intervals of 0.5 meters. For each set of third drilling parameters collected during each mixing process, each set of third torque values, third drill pressure values, actual sinking rate, and actual lifting rate is mapped to the corresponding depth interval according to the depth of the drill bit position. The same depth interval contains multiple sets of collected data during one mixing process; after multiple mixing cycles, multiple sets of torque values ​​and drill pressure values ​​are aggregated within the same depth interval.

[0048] In practical implementation, the torque variation coefficient for multiple sets of torque values ​​within each depth interval and the drill pressure variation coefficient for multiple sets of drill pressure values ​​within each depth interval are calculated. The variation coefficients are calculated according to the following formula:

[0049] in, The coefficient of variation represents the degree of dispersion of a set of data within the depth interval; is the standard deviation of a set of data within the depth interval; This is the mean of a set of data within the depth interval. When calculating the torque variation coefficient, Replace with torque variation coefficient. The standard deviation of multiple torque values ​​within the depth range. This is the average of multiple torque values ​​within the depth range. When calculating the coefficient of variation of drilling pressure... Replace with the coefficient of variation of drilling pressure. The standard deviation of multiple sets of drill pressure values ​​within the depth range. This represents the average of multiple sets of drill pressure values ​​within the depth range.

[0050] In some embodiments, standard deviation The calculation method is as follows: average the total torque or drilling pressure values ​​within the depth range to obtain the mean value. Then compare each torque value or drilling pressure value with the average value. The standard deviation is obtained by summing the squares of the differences, dividing by the number of values ​​involved in the calculation minus 1, and then taking the square root. .

[0051] The torque coefficient of variation (CV) for each depth interval was compared with a threshold value for the CV, and the drill pressure coefficient of variation (DP) for each depth interval was also compared with a threshold value for the DP. Both the CV and DP threshold values ​​were obtained from pre-construction test pile calibration. During the test piles, the CV and DP were calculated using the same data collection method and depth interval division method in known homogeneous cement-soil mixing piles. The maximum CV value across all depth intervals in the test piles was multiplied by 1.2 to obtain the corresponding CV threshold value. If the CV of the CV in a depth interval exceeds the threshold value, the corresponding depth interval is classified as a non-uniform interval; similarly, if the DP CV in a depth interval exceeds the threshold value for the DP, the corresponding depth interval is classified as a non-uniform interval.

[0052] The number of all non-uniform intervals is counted. If the number of non-uniform intervals exceeds a preset threshold, the uniformity of the current cement-soil mixing pile is determined to have failed to meet the preset standard. The preset threshold is determined based on the number of pile length and depth intervals, and is set to 25% of the total number of depth intervals.

[0053] In practice, if the uniformity of the current cement-soil mixing pile does not meet the preset standard, the actual soil layer category corresponding to the depth range of all identified non-uniform intervals is obtained. The actual soil layer category is obtained by comparing the depth range of the non-uniform interval with the soil interface depth in the 3D geological model. The soil layer elements in the 3D geological model contain soil property attributes; the soil property category of the soil layer elements is extracted from the 3D geological model according to the depth location of the non-uniform interval as the actual soil layer category.

[0054] The optimal mixing energy input value corresponding to each actual soil layer category is extracted from the 3D geological model. The optimal mixing energy input value is stored in the soil layer volume element attributes of the 3D geological model. The optimal mixing energy input value is obtained through field pile calibration. During calibration, multiple mixing tests are conducted in different soil types. The mixing energy input value when the uniformity of cement-soil mixing reaches the preset uniformity standard after mixing is taken as the optimal mixing energy input value.

[0055] Based on the optimal mixing energy input value, the target rotational speed and target lifting speed for each non-uniform interval during the next reciprocating mixing cycle are calculated. The target rotational speed and target lifting speed are determined as follows: a mapping table between the optimal mixing energy input value and the target rotational speed and target lifting speed is pre-stored in the drilling rig control system. This mapping table is generated based on the mixing energy input formula and the drilling rig performance curve, and the mixing energy input value is positively correlated with the target rotational speed and target lifting speed. The target rotational speed and target lifting speed are retrieved from the mapping table based on the optimal mixing energy input value for the non-uniform interval.

[0056] The drill bit rotation speed during the next reciprocating stirring cycle through the uneven zone is adjusted to the corresponding target rotation speed value, and the lifting speed and sinking speed during the uneven zone are also adjusted to the corresponding target lifting speed value. When the drill bit passes through the uneven zone during sinking, the adjustment focuses on the sinking speed value; when the drill bit passes through the uneven zone during lifting, the adjustment focuses on the lifting speed value. The drilling rig control system determines in real time whether it is in an uneven zone based on the depth position, and controls the power head, lifting cylinder, and feed cylinder according to the target rotation speed and target lifting speed or target sinking speed values ​​when entering an uneven zone.

[0057] In practice, during the entire process of drill bit descent and elution, when the third torque value exceeds the upper torque threshold corresponding to the current depth range, the vertical movement of the drill bit is paused and the first or second stirring speed is increased until the third torque value falls back below the upper torque threshold. The upper torque threshold is obtained from a preset stirring parameter table based on the soil type corresponding to the current depth range. Pausing the vertical movement of the drill bit is achieved by the drilling rig control system controlling the feed cylinder to stop oil supply. When increasing the first or second stirring speed, the first stirring speed is increased if the drill bit is descent, and the second stirring speed is increased if the drill bit is elution. The drilling rig control system continuously monitors the third torque value, and resumes the vertical movement of the drill bit once the third torque value drops below the upper torque threshold.

[0058] In practical implementation, the digital construction system for cement-soil mixing piles includes a memory, a processor, and a computer program stored in the memory and running on the processor. The memory uses a non-volatile storage medium and stores three-dimensional geological model data, drilling rig parameter configuration tables, sensor calibration parameters, computer program instructions, and construction process record data. The processor is connected to the memory, data acquisition interface, control output interface, and communication interface via a system bus. The data acquisition interface connects to torque sensors, pressure sensors, stroke sensors, tilt sensors, pressure transmitters, and grouting pump flow sensors. The control output interface connects to the drilling rig power head frequency converter, the electro-hydraulic proportional valve of the feed cylinder, the electro-hydraulic proportional valve of the lifting cylinder, the solenoid valve of the mast vertical adjustment cylinder, and the proportional valve of the grouting pump hydraulic motor. When the processor executes the computer program, the digital construction system for cement-soil mixing piles implements the steps of the aforementioned digital construction method for cement-soil mixing piles.

[0059] In practical implementation, the computer program is functionally divided into a data acquisition module, a geological model data interface module, a drilling control module, a grouting control module, a uniformity evaluation module, and an adjustment calculation module. The data acquisition module reads the output values ​​of each sensor at a fixed sampling frequency through the data acquisition interface, and aligns the sensor output values ​​by timestamp to form a first drilling parameter set, a second drilling parameter set, and a third drilling parameter set. The geological model data interface module reads the three-dimensional geological model data stored in the memory, queries the coordinates based on the drill bit position, and outputs the soil strength value, soil permeability coefficient, soil void ratio, soil type, and optimal mixing energy input value. The drilling control module calculates the adjustment amount for the first working state of the drilling rig based on the first drilling parameter set output by the data acquisition module and the soil strength value output by the geological model data interface module, and writes the adjustment amount to the control output interface. The grouting control module calculates the adjustment amounts for the grouting pressure and lifting rate based on the second drilling parameter set output by the data acquisition module and the soil permeability coefficient and soil void ratio output by the geological model data interface module, and writes the adjustment amounts to the control output interface. The uniformity evaluation module calculates the coefficient of variation for each depth interval and counts the number of non-uniform intervals based on the third drilling parameter set output by the data acquisition module. The adjustment calculation module calculates the target rotation speed and target lifting speed for the next reciprocating mixing cycle based on the actual soil layer type corresponding to the non-uniform interval and the optimal mixing energy input value.

[0060] In some embodiments, when the processor executes a computer program to implement the data acquisition module, it acquires a first set of drilling parameters at a first sampling frequency. The first sampling frequency is set to 10 Hz. The data acquisition module reads the first torque value output by the torque sensor, the first drilling pressure value output by the pressure sensor, and the vertical displacement of the drill bit output by the stroke sensor through the data acquisition interface, and calculates the first drilling rate based on the ratio of the difference between two consecutive vertical displacements of the drill bit to the first sampling period. The data acquisition module adds a timestamp to the read first torque value, the first drilling pressure value, and the calculated first drilling rate and stores them in the first drilling parameter set storage area in the memory.

[0061] In practical implementation, when the processor executes the computer program to implement the geological model data interface module, the geological model data interface module reads the three-dimensional geological model from memory. The three-dimensional geological model includes the coordinates of regular grid nodes, the depth of soil layer interfaces, and the attributes of soil layer elements. The geological model data interface module receives the current depth of the drill bit and the planar coordinates of the construction area provided by the drilling rig control system, and generates the current drill bit position query coordinates. Based on the current drill bit position query coordinates, the geological model data interface module locates the soil layer element in the three-dimensional geological model and reads the predicted soil layer strength value from the soil layer element attribute data. The geological model data interface module outputs the predicted soil layer strength value to the drilling control module.

[0062] In practical implementation, when the processor executes the computer program to implement the drilling control module, the drilling control module receives the predicted soil strength value from the geological model data interface module and calculates the theoretical drilling rate range according to the following formula:

[0063] in, This represents the lower limit of the theoretical drilling rate range, expressed in meters per minute. This represents the upper limit of the theoretical drilling rate range, expressed in meters per minute. The predicted soil strength value at the current drill bit location is extracted from the three-dimensional geological model, in megapascals (MPa). The coefficient for calculating the lower limit of the system drilling rate is expressed in megapascal-meters per minute. The coefficient is used to calculate the upper limit of the system drilling rate, with the unit being megapascal-meter per minute.

[0064] and The method for obtaining the data is as follows: A calibration test is conducted in a representative soil layer of the construction area. The output speed of the drilling rig's power head is set to 80% of the rated speed, and the feed cylinder pressure is set to 80% of the rated pressure. The drilling rate and the corresponding soil layer strength value are recorded. The drilling rate is multiplied by the corresponding soil layer strength value to obtain the data. Set the output speed of the drill rig's power head to the rated speed, set the feed cylinder pressure to the rated pressure, record the drill bit's drilling rate and the corresponding soil strength value, and multiply the drilling rate by the corresponding soil strength value to obtain the final value. When the calibration test covers multiple representative soil layers, Take the average value of the calibration results for all representative soil layers. Take the average value of the calibration results for all representative soil layers.

[0065] The drilling control module compares the first drilling rate provided by the data acquisition module with the theoretical drilling rate range. If the first drilling rate exceeds the theoretical drilling rate range, the drilling control module calculates the adjustment amount and sends it to the drill rig's power head inverter and the feed cylinder electro-hydraulic proportional valve through the control output interface. This adjusts the output speed of the drill rig's power head and the pressure of the feed cylinder, bringing the first drilling rate back to within the theoretical drilling rate range. The adjustment amount is calculated using the following formula:

[0066] in, This is the adjustment value for the first working state of the drilling rig, dimensionless; The first torque value provided in real time to the data acquisition module, in Newton-meters; The first drilling pressure value provided in real time to the data acquisition module, in kilonewtons; Rated torque of the power head (unit: Newton-meter); Rated drilling pressure (unit: kN); The torque adjustment weight is dimensionless. The weight for adjusting drilling pressure is dimensionless. and The values ​​range from 0.3 to 0.7, and and The sum is 1.0.

[0067] and The method for obtaining the values ​​is as follows: During on-site calibration before construction, the output speed of the drilling rig's power head and the pressure of the feed cylinder are changed respectively. The response sensitivity of the first torque value and the first drilling pressure value to the first drilling rate is recorded. The response sensitivity of the first torque value and the response sensitivity of the first drilling pressure value are normalized and used as the data respectively. and When the response sensitivity of the first torque value is equal to the response sensitivity of the first drilling pressure value, and All are set to 0.5. and The basis for setting it to 0.5 is that the first torque value and the first drilling pressure value contribute equally to the control of the first drilling rate.

[0068] In practical implementation, when the processor executes the computer program to implement the shotcrete control module, the drilling rig control system sends a shotcrete start signal to the shotcrete control module when it detects that the drill bit has reached the preset design pile bottom elevation. The shotcrete control module starts the shotcrete pump through the control output interface, and the shotcrete pump injects cement slurry into the soil at a first shotcrete pressure. Simultaneously, the shotcrete control module collects a second torque value, a second drilling pressure value, a drill bit lifting rate, and the real-time shotcrete pressure value of the shotcrete pump at a second sampling frequency through the data acquisition interface, forming a second drilling parameter set. The second sampling frequency is set to 5 Hz. While collecting the second drilling parameter set, the shotcrete control module reads the output of the tilt sensor and calculates the verticality deviation value. When the verticality deviation value exceeds a preset deviation threshold, the shotcrete control module controls the mast tilting cylinder solenoid valve to adjust the drilling rig mast tilt angle through the control output interface.

[0069] In practical implementation, the shotcrete control module extracts the soil permeability coefficient and void ratio at the current drill bit position from the 3D geological model through the geological model data interface module, calculates the theoretical cement slurry diffusion rate, and adjusts the output flow of the shotcrete pump hydraulic motor according to the theoretical cement slurry diffusion rate through the control output interface, so that the real-time shotcrete pressure value reaches the shotcrete pressure value that matches the theoretical cement slurry diffusion rate. Simultaneously, the shotcrete control module adjusts the drill bit lifting rate through the control output interface based on the second torque value and the second drilling pressure value.

[0070] In practical implementation, when the processor executes the computer program to implement the uniformity evaluation module, after the drill bit is raised to the preset design pile top elevation, the uniformity evaluation module continuously collects the third torque value, third drilling pressure value, actual sinking rate, and actual lifting rate at a third sampling frequency through the data acquisition module, as the third drilling parameter set. The third sampling frequency is set to 5 Hz. The uniformity evaluation module divides the multiple third drilling parameter sets collected during the repeated stirring process into depth intervals, each depth interval being a depth segment with a fixed interval of 0.5 meters starting from the pile bottom elevation. The uniformity evaluation module calculates the torque variation coefficient and the drilling pressure variation coefficient of multiple sets of torque values ​​within each depth interval, and compares the torque variation coefficient with the torque variation coefficient threshold and the drilling pressure variation coefficient with the drilling pressure variation coefficient threshold. If the torque variation coefficient or drilling pressure variation coefficient of any depth interval exceeds the corresponding variation coefficient threshold, the corresponding depth interval is determined to be a non-uniform interval.

[0071] In practical implementation, when the processor executes the computer program to implement the adjustment calculation module, the adjustment calculation module receives a list of non-uniform intervals provided by the uniformity evaluation module. The adjustment calculation module obtains the actual soil layer category corresponding to the depth position of each non-uniform interval through the geological model data interface module, and reads the optimal mixing energy input value corresponding to each actual soil layer category from the three-dimensional geological model. Based on the optimal mixing energy input value, the adjustment calculation module queries the optimal mixing parameter mapping table pre-stored in memory to obtain the target rotation speed value and target lifting speed value corresponding to each non-uniform interval. The adjustment calculation module sends the target rotation speed value and target lifting speed value to the drilling control module. During the next reciprocating mixing process, the drilling control module compares the drill bit depth position with the depth range of the non-uniform interval in real time. When the drill bit enters the non-uniform interval, it adjusts the drill bit rotation speed to the corresponding target rotation speed value through the control output interface, and adjusts the lifting speed or sinking speed to the corresponding target lifting speed value.

[0072] In practical implementation, the processor executing the computer program also performs the following functions: throughout the entire process of drill bit descent and descent, when the third torque value exceeds the upper limit threshold of torque corresponding to the current depth range, the vertical movement of the drill bit is paused and the first or second stirring speed is increased until the third torque value falls back below the upper limit threshold. Pausing the vertical movement of the drill bit is achieved by stopping the oil supply to the feed cylinder through the control output interface, and increasing the first or second stirring speed is achieved by adjusting the output frequency of the power head inverter through the control output interface.

[0073] In some embodiments, the computer program stored in the memory further includes a data recording module. The data recording module writes the first drilling parameter set, the second drilling parameter set, the third drilling parameter set, the adjustment amount, the non-uniformity interval determination result, the target rotation speed value, and the target lifting speed value into the construction process record data area in the memory according to the construction pile number and time sequence, for construction quality traceability and remote monitoring.

[0074] See Figure 4 The vertical axis of the graph represents the magnified values ​​of the torque variation coefficient and the drill pressure variation coefficient (both multiplied by 100), as well as the actual or target values ​​of the drill bit rotation speed and hoisting speed, in revolutions per minute (rpm) and dimensionless scaling of the hoisting speed, respectively. The horizontal axis represents the pile depth, ranging from 0 meters to 30 meters. The curve colors and line types represent different parameters: the solid blue line represents the torque variation coefficient × 100, the dashed red line represents the drill pressure variation coefficient × 100, the dotted green line represents the target rotation speed, the dashed orange line represents the target hoisting speed × 30, and the solid purple line represents the current drill bit rotation speed.

[0075] As shown in the figure, the torque variation coefficient and drill pressure variation coefficient exhibit periodic fluctuations throughout the overall depth range, both remaining at low levels (fluctuating between approximately 3 and 18). This indicates that the variability of the drill bit load parameters is small during the construction of the cement-soil mixing pile, meeting the requirements for uniformity evaluation. Both the target lifting speed and the current drill bit rotation speed fluctuate with depth, with the fluctuation range of the target lifting speed being significantly higher than that of the drill bit rotation speed, indicating that lifting speed adjustment is more sensitive to mixing uniformity control.

[0076] In the depth range of approximately 5 to 10 meters, both the torque and drill pressure variability coefficients showed local peaks, indicating significant load fluctuations and a potentially non-uniform range. Correspondingly, the target rotational speed and target lifting speed values ​​showed adjustment trends, with the target rotational speed slightly decreasing and the target lifting speed decreasing to adapt to the soil characteristics. The current drill bit speed also adjusted accordingly, reflecting the system's dynamic adjustment of construction parameters based on the uniformity evaluation results. In the depth range of approximately 15 to 20 meters, both the torque and drill pressure variability coefficients increased again, but the magnitude was less than in the previous range. The target rotational speed and target lifting speed values ​​were adjusted accordingly, with the target lifting speed reaching its peak, indicating an increased lifting rate to enhance the mixing effect. The current drill bit speed remained at a high level to ensure mixing efficiency. In the depth range of approximately 25 to 30 meters, the torque variability coefficient decreased significantly to a low point, while the drill pressure variability coefficient showed an upward trend. The target rotational speed gradually recovered to near its initial value, while the target lifting speed gradually decreased. The current drill bit speed also changed with the target rotational speed, indicating that the construction parameters were returning to normal and the mixing process was stable.

[0077] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A digital construction method for cement-soil mixing piles, characterized in that, The method includes: Obtain stratigraphic distribution data of the construction area and generate a three-dimensional geological model based on the stratigraphic distribution data; During the drilling process, the first set of drilling parameters of the drill bit is collected in real time, and the first working state of the drilling rig is dynamically adjusted according to the first set of drilling parameters and the three-dimensional geological model. When the drill bit reaches the preset design pile bottom elevation, the grouting pump is started to spray cement grout into the soil, and the second drilling parameter set during the drill bit lifting process is collected in real time. Based on the second drilling parameter set and the three-dimensional geological model, the lifting speed of the drill bit and the grouting pressure of the grouting pump are dynamically adjusted. After the drill bit is raised to the preset design pile top elevation, the drilling rig is controlled to perform multiple reciprocating stirring operations, and a third set of drilling parameters is collected during each reciprocating stirring process; Based on the multiple sets of the third drilling parameters collected during the repeated mixing process, the uniformity of the current cement-soil mixing pile is determined. If the uniformity of pile formation does not meet the preset standard, the drill bit rotation speed and lifting speed for the next reciprocating stirring will be adjusted according to the currently collected third drilling parameter set and the three-dimensional geological model.

2. The digital construction method for cement-soil mixing piles according to claim 1, characterized in that, Acquire stratigraphic distribution data of the construction area and generate a three-dimensional geological model based on the stratigraphic distribution data, specifically including: Multiple exploration points are set up within the construction area according to a preset grid spacing, and continuous formation penetration resistance data are obtained at each exploration point through static cone penetration tests. Based on the ground penetration resistance data, the soil interface depth at each of the exploration points is determined, and the soil property category of each soil layer is identified. Input the soil interface depth and soil property type of all the exploration points into the three-dimensional interpolation engine to generate an initial three-dimensional geological body that reflects the stratum distribution in the construction area. Using existing geological borehole columnar sections within the construction area as rigid constraints, the local boundaries of the initial three-dimensional geological body are corrected to obtain the three-dimensional geological model.

3. The digital construction method for cement-soil mixing piles according to claim 1, characterized in that, During the drilling process, the first set of drilling parameters from the drill bit is acquired in real time, and the first working state of the drilling rig is dynamically adjusted based on the first set of drilling parameters and the three-dimensional geological model, specifically including: During the drilling process of the drilling rig, the first torque value, the first drilling pressure value and the first drilling rate of the drill bit are collected at a first sampling frequency to form the first drilling parameter set; The predicted soil strength value at the current drill bit position is extracted from the three-dimensional geological model, and the theoretical drilling rate range of the drill bit is calculated based on the predicted soil strength value. The first drilling rate is compared with the theoretical drilling rate range. If the first drilling rate exceeds the theoretical drilling rate range, the power head output speed and feed cylinder pressure of the drilling rig are adjusted so that the first drilling rate returns to the theoretical drilling rate range.

4. The digital construction method for cement-soil mixing piles according to claim 1, characterized in that, When the drill bit reaches the preset design pile bottom elevation, the grouting pump is started to spray cement grout into the soil, and the second drilling parameter set during the drill bit lifting process is collected in real time, specifically including: When the drill bit reaches the preset design pile bottom elevation, the grouting pump is triggered to start and cement grout is sprayed into the soil at the first grouting pressure. At the same time, the drilling rig is controlled to switch to the lifting mode. During the drill bit lifting process, the second torque value, second drilling pressure value, lifting rate and real-time grouting pressure value of the grouting pump of the drill bit are collected at a second sampling frequency to form the second drilling parameter set; While collecting the second set of drilling parameters, the verticality deviation of the drill bit is monitored in real time. If the verticality deviation exceeds a preset deviation threshold, the mast tilt angle of the drilling rig is adjusted.

5. The digital construction method for cement-soil mixing piles according to claim 4, characterized in that, Based on the second drilling parameter set and the three-dimensional geological model, the lifting speed of the drill bit and the grouting pressure of the grouting pump are dynamically adjusted, specifically including: Extract the soil permeability coefficient and soil porosity ratio at the current drill bit location from the three-dimensional geological model; Calculate the theoretical cement slurry diffusion rate at the current soil layer location based on the soil layer permeability coefficient and the soil layer void ratio; The real-time grouting pressure value is adjusted to a grouting pressure value that matches the theoretical cement slurry diffusion rate, and the drill bit lifting rate is adjusted according to the second torque value and the second drilling pressure value.

6. The digital construction method for cement-soil mixing piles according to claim 1, characterized in that, After the drill bit is raised to the preset design pile top elevation, the drilling rig is controlled to perform multiple reciprocating mixing operations, and a third set of drilling parameters is collected during each reciprocating mixing process, specifically including: After the drill bit is raised to the preset design pile top elevation, the power head of the drilling rig is controlled to reverse, driving the drill bit to sink from the pile top elevation to the pile bottom elevation at a first sinking rate, and cutting the cement soil at a first mixing speed during the sinking process; When the drill bit reaches the bottom elevation of the pile again, the power head is controlled to rotate forward, driving the drill bit to be lifted from the bottom elevation of the pile to the top elevation of the pile at the first lifting rate, and the cement soil is cut twice at the second mixing speed during the lifting process; Throughout the entire process of the drill bit sinking and lifting, the third torque value, third drilling pressure value, actual sinking rate, and actual lifting rate of the drill bit are continuously collected at a third sampling frequency, which serve as the third drilling parameter set.

7. The digital construction method for cement-soil mixing piles according to claim 1, characterized in that, Based on multiple sets of the third drilling parameters collected during repeated mixing processes, the uniformity of the current cement-soil mixing pile is determined, specifically including: The multiple sets of the third drilling parameters collected during the repeated stirring process are divided into depth intervals to obtain multiple sets of torque values ​​and drilling pressure values ​​corresponding to each depth interval. Calculate the torque variation coefficient of multiple sets of torque values ​​within each depth interval, and the drill pressure variation coefficient of multiple sets of drill pressure values ​​within each depth interval; The torque variation coefficient and the drilling pressure variation coefficient of each depth interval are compared with their respective corresponding variation coefficient thresholds. If the torque variation coefficient or the drilling pressure variation coefficient of any depth interval exceeds the corresponding variation coefficient threshold, the depth interval is determined to be an uneven interval. The number of all uneven intervals is counted. If the number of uneven intervals exceeds a preset threshold, it is determined that the uniformity of the current cement-soil mixing pile has not reached the preset standard.

8. The digital construction method for cement-soil mixing piles according to claim 7, characterized in that, If the uniformity of pile formation does not meet the preset standard, the drill bit rotation speed and lifting speed for the next reciprocating stirring operation will be adjusted based on the currently collected third drilling parameter set and the three-dimensional geological model. Specifically, this includes: Obtain the actual soil layer category corresponding to all depth intervals that are determined to be non-uniform intervals, and extract the optimal mixing energy input value corresponding to each actual soil layer category from the three-dimensional geological model; Based on the optimal stirring energy input value, calculate the target rotation speed and target lifting speed value for each non-uniform interval during the next reciprocating stirring; The drill bit speed during the next reciprocating stirring cycle when passing through the uneven zone is adjusted to the corresponding target speed value, and the lifting speed or sinking speed when passing through the uneven zone is adjusted to the corresponding target lifting speed value.

9. The digital construction method for cement-soil mixing piles according to claim 6, characterized in that, During the entire process of the drill bit sinking and lifting, when the third torque value exceeds the upper limit threshold of torque corresponding to the current depth range, the vertical movement of the drill bit is paused and the first stirring speed or the second stirring speed is increased until the third torque value falls back below the upper limit threshold of torque.

10. A digital construction system for cement-soil mixing piles, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the digital construction method for cement-soil mixing piles as described in any one of claims 1 to 9.

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