Test method for determining aperture of high-pressure jet grouting pre-drilling hole
Through sensor monitoring and mathematical model adjustment of the guide hole diameter, the problem of selecting the guide hole diameter in high-pressure rotary spray construction is solved, the smoothness and quality assurance of rotary spray construction is achieved, and the construction cost is reduced.
Patent Information
- Application Number
- CN202411368418.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2025-01-07
AI Technical Summary
In high-pressure rotary spraying construction, it is difficult to balance the rotary spraying effect and construction cost when the diameter of the guide hole is selected. Too small leads to excessive pressure in the ground and collapse of soil. Too large increases the construction cost and affects the quality of the pile body.
Sensors are used to monitor the pressure, flow rate and pore water pressure during the rotary spraying process, and adjust the diameter of the guide holes through mathematical models to ensure the smoothness and quality of the rotary spraying construction.
By quantifying the monitoring and adjusting the diameter of the guide hole, the smoothness of the rotary spray construction and the quality of the pile body are ensured, while reducing construction costs.
Smart Images
Figure CN119266299A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of pile foundation construction, and in particular relates to a test method for determining the aperture of a high-pressure rotary jet pre-drilled hole. Background Art
[0002] High-pressure jet grouting construction technology uses a rotating nozzle to spray high-speed fluid while cutting the soil and mixing cement slurry with the chopped soil. After chemical reaction, a solid reinforced soil column is formed with a strength of more than several megapascals. This method was invented by Dr. Nakanishi Shigeki of NIT in Japan. It was originally a simple single-tube method (also known as the CCP method), and then the double-tube method and triple-tube method were developed. The single-tube method only sprays cement slurry; the double-tube method uses compressed air to coaxially wrap high-pressure cement slurry to cut the soil and mix the two, so that the diameter of the reinforced body is greatly increased compared with the single-tube method; the triple-tube method uses compressed air to coaxially wrap high-pressure water flow to first cut the soil, forming a larger diameter of the broken soil gap, and then injects cement slurry with a mud pump to fill and mix, so that the diameter of the reinforced body is greatly increased compared with the first two methods. Later, super jet grouting technology, double high-pressure jet grouting technology, cross-jet jet grouting technology, double-liquid jet grouting technology, etc. were developed to make the diameter of the generated pile larger and larger. Since my country successfully developed the high-pressure rotary grouting construction technology in the late 1970s, this method has been widely used in many engineering fields in China, such as anti-seepage walls of water conservancy projects, urban underground projects, slope stability, docks, bridge foundations, etc.
[0003] During the construction of jet grouting piles, it is often necessary to use a hole-drawing device for hole-drawing construction. During the jet grouting construction process, slurry and gas are sprayed in the form of high pressure to break the surrounding soil, resulting in an increase in deep ground pressure. Part of the slurry and gas are discharged to the ground along the hole-drawing, thereby reducing the increase in ground pressure caused by the jet grouting. Therefore, the diameter of the hole-drawing directly affects the effect of the grouting. If the diameter is too small, the grouting effect is not good, resulting in excessive ground pressure causing the collapse of the upper soil of the jet grouting pile, and excessive pressure penetrating the surrounding soil into the surrounding unsolidified pile body, affecting the overall quality of the pile body. However, the hole-drawing cannot be increased infinitely. If the hole-drawing diameter is too large, it will cause local collapse in the hole, and a large aperture will also increase the construction cost. Therefore, it is important to reasonably select the diameter of the hole-drawing according to the parameters of the jet grouting construction. Based on this, the present invention proposes a test method for determining the aperture of a high-pressure jet grouting pre-drilled hole. Summary of the invention
[0004] In view of the above technical problems existing in the prior art, the present invention proposes a test method for determining the diameter of a high-pressure jet grouting pre-drilled hole, which overcomes the shortcomings of the prior art. The sensor quantifies the impact on the surrounding area during the jet grouting process, thereby reflecting the suitability of the lead hole diameter in the jet grouting process. By adjusting the lead hole diameter, the jet grouting construction is smooth, and thus no problems with the pile quality are caused.
[0005] In order to achieve the above object, the present invention adopts the following technical solution: A test method for determining the hole diameter of a high-pressure jet grouting pre-drilled hole is constructed using jet grouting equipment, including a drill rod, a drilling rig, and monitoring equipment including a pressure sensor, a pore water pressure sensor, a flow meter, and an inclinometer tube. The pressure sensor is installed around the nozzle at the lower end of the drill rod, and the pore water pressure sensor and the inclinometer tube are installed around the designed pile diameter of the jet grouting pile. The specific test method is as follows: Step 1: Drilling hole construction The diameter of the pilot hole is set according to the diameter of the drill rod. The initial pilot hole diameter is 1.2-1.5 times the diameter of the drill rod to ensure the verticality of the pilot hole and the pilot hole depth reaches the designed depth of the jet grouting pile. Step 2: Sensor Installation Install pore water pressure sensors and inclinometers around the designed location of the jet grouting piles, set flow meters at the orifices of the lead holes, and check the access conditions of the sensors; Step 3: Spraying construction The construction is carried out according to the designed jet grouting parameters. During the construction process, the pressure sensors and flow meters are continuously measured. As the jet grouting construction proceeds, all pore water pressure sensors at the jet grouting pile construction depth and within the range of 2-3m above and below are continuously measured in real time. The changes in deep horizontal displacement are detected by the inclinometer. The detection range is the jet grouting pile construction depth and within the range of 2-8m above and below. Step 4: Monitoring data determination The suitability of the initial borehole diameter is determined based on the monitoring data of the pressure sensor, pore water pressure sensor, flow meter, and inclinometer. The four specific determination conditions are as follows: Judgment condition 1: Assume that the monitoring data of the pressure sensor is a. When a is greater than 10% of the static pressure of the mud at the depth, it is scored as 1. For every 1% increase, the score increases by 1. Judgment condition 2: Assuming that the monitoring data of the flow meter is b, when b is less than 80% of the grouting volume, it is recorded as a score of 1. Compared with 80% of the grouting volume, for every 5% decrease, the score increases by 1. Judgment condition three: Assuming that the monitoring data of the pore water pressure sensor is c, when c is greater than N times the normal pressure head pressure at the depth, it is recorded as a score of 1. Compared with N times the normal pressure head pressure, the score increases by 1 for every 0.1 times increase; Judgment condition 4: Assuming that the monitoring data of deep horizontal displacement is d, when d is greater than the initial measurement value of 30mm before rotary grouting construction, it is scored as 1. Compared with the deep horizontal displacement of 30mm, the score increases by 1 for every increase of 1mm; Conduct sensitivity analysis on the monitoring data of the four judgment conditions to determine the weight values of different monitoring data. The weights of judgment conditions one to four are A, B, C, and D respectively. Then the mathematical model of the comprehensive evaluation value is N=A*a+B*b+C*c+Dd; Step 5: Initial hole diameter adjustment The initial lead hole diameter is adjusted according to the evaluation score of the mathematical model. When the mathematical model score is less than 4, the initial lead hole diameter is not adjusted; when the mathematical model score is greater than or equal to 4 and less than 6, the initial lead hole diameter is adjusted to 1.1-1.2 times the original diameter; when the mathematical model score is greater than or equal to 6 and less than 8, the initial lead hole diameter is adjusted to 1.3-1.4 times the original diameter; when the mathematical model score is greater than or equal to 8 and less than 10, the initial lead hole diameter is adjusted to 1.5-1.6 times the original diameter; when the mathematical model score is greater than or equal to 10, the initial lead hole diameter is adjusted to 2.0 times the original diameter; Step 6: Verification and optimization of the hole diameter adjustment results In the same construction site, use the adjusted hole diameter for construction work, use the designed jet grouting parameters for construction, and make judgments and adjustments according to the adjustment method in step five until the jet grouting diameter does not need to be adjusted.
[0006] Preferably, N times the atmospheric head pressure is determined based on field measurements, and the range of N under different geological conditions is 1.0-3.0.
[0007] Preferably, the installation positions of the pore water pressure sensors are as follows: from a top view, the installation positions are arranged in a circle around the designed pile diameter of the jet grouting pile, the installation positions are 0.8-2.0 times the pile diameter away from the pile center, and 2-4 installation positions are evenly arranged around each jet grouting pile; from a cross-sectional view, a pore water pressure sensor is arranged at each installation position every 0.5m-2.0m along the construction depth of the jet grouting pile.
[0008] Preferably, the installation position of the inclinometer tube is as follows: from a top view, the installation positions are arranged in a ring around the designed pile diameter of the rotary jet pile, the installation positions are 0.8-2.0 times the pile diameter away from the pile center, and 2-4 installation positions are evenly arranged around each rotary jet pile; from a cross-sectional view, an inclinometer tube is installed at each installation position along the construction depth of the rotary jet pile, and the installation positions of the inclinometer tube and the pore water pressure sensor are on the same circular ring, and the two are arranged crosswise.
[0009] Beneficial technical effects brought by the present invention: The sensor is used to quantify the impact of the jet grouting process on the surrounding area, and then reflect the suitability of the guide hole diameter in the jet grouting process. By adjusting the guide hole diameter, the jet grouting construction is smooth, and there will be no problems with the pile quality. The core parameters of the jet grouting pile are pressure, flow, and acceleration, and the corresponding ones are pressure sensors, pore water pressure sensors, flow meters, and inclinometers. Therefore, the core parameters of the jet grouting are systematically quantified to more intuitively show the impact of the design parameters on the surrounding area. However, in order to achieve the designed pile diameter, the jet grouting parameters must not be reduced. Therefore, the slurry channel has a particularly significant impact on the pile quality, and the most direct return slurry channel is the guide hole diameter. Therefore, by adjusting the guide hole diameter through this kind of monitoring, both the quantification purpose is achieved and the construction quality of the jet grouting pile is guaranteed. In addition, from the perspective of the mechanism of jet grouting, the larger the diameter of the guide hole, the smoother the slurry return, but the larger the diameter, the higher the construction cost, and it has a greater impact on the jet grouting diameter. If the slurry return is too smooth, the ability of the slurry to maintain a stable pressure will be reduced, and the in-situ soil cannot be continuously fractured and crushed. Therefore, finding a suitable guide hole diameter through the present invention can not only ensure the quality of the jet grouting, but also reduce the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 A cross-sectional schematic diagram of the overall structure of a test method for determining the aperture of a high-pressure jet-jet pre-drilled hole according to the present invention; Figure 2 A schematic top view of the relationship between the installation positions of the pore water pressure sensor and the inclinometer tube and the position of the jet grouting pile in a test method for determining the aperture of a high-pressure jet grouting pre-drilled hole according to the present invention; Figure 3 A schematic cross-sectional view of the relationship between the installation position of a pore water pressure sensor and the position of a jet grouting pile in a test method for determining the aperture of a high-pressure jet grouting pre-drilled hole according to the present invention; Figure 4 It is a cross-sectional schematic diagram of the relationship between the installation position of the inclinometer tube and the position of the jet grouting pile in a test method for determining the aperture of a high-pressure jet grouting pre-drilled hole of the present invention; Among them, 1-drill pipe, 2-pressure sensor, 3-flow meter, 4-pore water pressure sensor, 5-inclinometer tube, 6-rotational jet slurry cluster flow. DETAILED DESCRIPTION
[0011] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Embodiment 1:
[0012] like Figure 1-4As shown, a test method for determining the hole diameter of a high-pressure jet grouting pre-drilling hole is constructed using jet grouting equipment, including a drill rod 1, a drilling rig, and monitoring equipment including a pressure sensor 2, a pore water pressure sensor 4, a flow meter 3, and an inclinometer tube 5, wherein the pressure sensor 2 is installed around the nozzle at the lower end of the drill rod 1, and the pore water pressure sensor 4 and the inclinometer tube 5 are both installed around the designed pile diameter of the jet grouting pile. The specific test method is as follows: Step 1: Drilling hole construction The diameter of the pilot hole is set according to the diameter of the drill rod 1. The initial pilot hole diameter is 1.2-1.5 times the diameter of the drill rod 1 to ensure the verticality of the pilot hole and the pilot hole depth reaches the design depth of the jet grouting pile. Step 2: Sensor Installation Install pore water pressure sensors 4 and inclinometer tubes 5 around the designed position of the jet grouting pile, set a flow meter 3 at the orifice of the lead hole, and check the passage of the sensors; Step 3: Spraying construction The construction is carried out according to the designed jet grouting parameters. During the construction process, the pressure sensor 2 and the flow meter 3 are continuously measured. As the jet grouting construction proceeds, all pore water pressure sensors 4 at the jet grouting pile construction depth and within the range of 2-3m above and below are continuously measured in real time. The change of deep horizontal displacement is detected by the inclinometer 5. The detection range is the jet grouting pile construction depth and within the range of 2-8m above and below. Step 4: Monitoring data determination The suitability of the initial borehole diameter is determined based on the monitoring data of the pressure sensor 2, the pore water pressure sensor 4, the flow meter 3, and the inclinometer tube 5. The specific four determination conditions are as follows: Judgment condition 1: Assume that the monitoring data of pressure sensor 2 is a. When a is greater than 10% of the static pressure of mud at the depth, it is recorded as score 1. For every 1% increase, the score increases by 1. Judgment condition 2: Assuming that the monitoring data of flow meter 3 is b, when b is less than 80% of the grouting volume, it is recorded as a score of 1. Compared with 80% of the grouting volume, for every 5% decrease, the score increases by 1. Judgment condition three: Assuming that the monitoring data of the pore water pressure sensor 4 is c, when c is greater than N times the normal pressure head pressure at the depth, it is recorded as a score of 1, and the score increases by 1 for every 0.1 times increase compared to N times the normal pressure head pressure; Judgment condition 4: Assuming that the monitoring data of deep horizontal displacement is d, when d is greater than the initial measurement value of 30mm before rotary grouting construction, it is scored as 1. Compared with the deep horizontal displacement of 30mm, the score increases by 1 for every increase of 1mm; Conduct sensitivity analysis on the monitoring data of the four judgment conditions to determine the weight values of different monitoring data. The weights of judgment conditions one to four are A, B, C, and D respectively. Then the mathematical model of the comprehensive evaluation value is N=A*a+B*b+C*c+Dd; Step 5: Initial hole diameter adjustment The initial lead hole diameter is adjusted according to the evaluation score of the mathematical model. When the mathematical model score is less than 4, the initial lead hole diameter is not adjusted; when the mathematical model score is greater than or equal to 4 and less than 6, the initial lead hole diameter is adjusted to 1.1-1.2 times the original diameter; when the mathematical model score is greater than or equal to 6 and less than 8, the initial lead hole diameter is adjusted to 1.3-1.4 times the original diameter; when the mathematical model score is greater than or equal to 8 and less than 10, the initial lead hole diameter is adjusted to 1.5-1.6 times the original diameter; when the mathematical model score is greater than or equal to 10, the initial lead hole diameter is adjusted to 2.0 times the original diameter; Step 6: Verification and optimization of the hole diameter adjustment results In the same construction site, use the adjusted hole diameter for construction work, use the designed jet grouting parameters for construction, and make judgments and adjustments according to the adjustment method in step five until the jet grouting diameter does not need to be adjusted.
[0013] Preferably, N times the atmospheric head pressure is determined based on field measurements, and the range of N under different geological conditions is 1.0-3.0.
[0014] Preferably, the installation position of the pore water pressure sensor 4 is as follows: from a top view, the installation positions are arranged in a ring around the designed pile diameter of the rotary jet pile, the installation positions are 0.8-2.0 times the pile diameter away from the center of the pile, and 2-4 installation positions are evenly arranged around each rotary jet pile; from a cross-sectional view, a pore water pressure sensor 4 is arranged at each installation position every 0.5m-2.0m along the construction depth of the rotary jet pile.
[0015] Preferably, the installation position of the inclinometer tube 5 is as follows: from a top view, the installation positions are arranged in a ring around the designed pile diameter of the jet grouting pile, the installation positions are 0.8-2.0 times the pile diameter away from the pile center, and 2-4 installation positions are evenly arranged around each jet grouting pile; from a cross-sectional view, an inclinometer tube 5 is installed at each installation position along the construction depth of the jet grouting pile, and the installation positions of the inclinometer tube 5 and the pore water pressure sensor 2 are both on the same circular ring, and the two are arranged crosswise. Embodiment 2:
[0016] like Figure 1-4 As shown, a test method for determining the hole diameter of a high-pressure jet grouting pre-drilling hole is constructed using jet grouting equipment, including a drill rod 1, a drilling rig, and monitoring equipment including a pressure sensor 2, a pore water pressure sensor 4, a flow meter 3, and an inclinometer tube 5, wherein the pressure sensor 2 is installed around the nozzle at the lower end of the drill rod 1, and the pore water pressure sensor 4 and the inclinometer tube 5 are both installed around the designed pile diameter of the jet grouting pile. The specific test method is as follows: Step 1: Drilling hole construction The diameter of the pilot hole is set according to the diameter of the drill rod 1. The initial pilot hole diameter is 1.3 times the diameter of the drill rod 1 to ensure the verticality of the pilot hole and the pilot hole depth reaches the design depth of the jet grouting pile. From the perspective of the mechanism of jet grouting, the larger the diameter of the guide hole, the smoother the slurry return, but the larger the diameter, the higher the construction cost, and it has a greater impact on the diameter of the jet grouting. If the slurry return is too smooth, the ability of the slurry to maintain a stable pressure will be reduced, and the in-situ soil cannot be continuously fractured and crushed. Therefore, finding a suitable guide hole diameter through the present invention can not only ensure the quality of the jet grouting, but also reduce the construction cost.
[0017] Step 2: Sensor Installation Install pore water pressure sensors 4 and inclinometer tubes 5 around the designed position of the jet grouting pile, set a flow meter 3 at the orifice of the lead hole, and check the passage of the sensors; Step 3: Spraying construction The construction is carried out according to the designed jet grouting parameters. During the construction process, the pressure sensor 2 and the flow meter 3 are continuously measured. As the jet grouting construction proceeds, all pore water pressure sensors 4 are continuously measured at the jet grouting pile construction depth and within the range of 3m above and below in real time. The change of deep horizontal displacement is detected by the inclinometer 5. The detection range is the jet grouting pile construction depth and within the range of 5m above and below. The core parameters of the rotary jet pile are pressure, flow rate, and acceleration, and the corresponding ones are pressure sensor 2, pore water pressure sensor 4, flow meter 3, and inclinometer tube 5. Therefore, the core parameters of the rotary jet are systematically quantified, and the influence of the design parameters on the surrounding area is more intuitively displayed. However, in order to achieve the designed pile diameter, the rotary jet parameters must not be reduced. Therefore, the slurry channel has a particularly significant impact on the pile body quality, and the most direct return slurry channel is the guide hole diameter. Therefore, by adjusting the guide hole diameter through this kind of monitoring, the purpose of quantification is achieved and the construction quality of the rotary jet pile is guaranteed.
[0018] Step 4: Monitoring data determination The suitability of the initial borehole diameter is determined based on the monitoring data of the pressure sensor 2, the pore water pressure sensor 4, the flow meter 3, and the inclinometer tube 5. The specific four determination conditions are as follows: Judgment condition 1: Assume that the monitoring data of pressure sensor 2 is a. When a is greater than 10% of the static pressure of mud at the depth, it is recorded as score 1. For every 1% increase, the score increases by 1. Judgment condition 2: Assuming that the monitoring data of flow meter 3 is b, when b is less than 80% of the grouting volume, it is recorded as a score of 1. Compared with 80% of the grouting volume, for every 5% decrease, the score increases by 1. Judgment condition three: Assuming that the monitoring data of the pore water pressure sensor 4 is c, when c is greater than N times the normal pressure head pressure at the depth, it is recorded as a score of 1, and the score increases by 1 for every 0.1 times increase compared to N times the normal pressure head pressure; Judgment condition 4: Assuming that the monitoring data of deep horizontal displacement is d, when d is greater than the initial measurement value of 30mm before rotary grouting construction, it is scored as 1. Compared with the deep horizontal displacement of 30mm, the score increases by 1 for every increase of 1mm; Conduct sensitivity analysis on the monitoring data of the four judgment conditions to determine the weight values of different monitoring data. The weights of judgment conditions one to four are A, B, C, and D respectively. Then the mathematical model of the comprehensive evaluation value is N=A*a+B*b+C*c+Dd. Because the sensitivity of each judgment condition is different, in order to reduce the impact of sensitivity on the comprehensive evaluation value, the weight of the parameter with high sensitivity is lowered, and the weight of the parameter with low sensitivity is increased. For example, the monitoring value of the pressure sensor directly reflects the state of the slurry return, and its sensitivity is significantly higher than the other three parameters. The specific weight algorithm can adopt factor analysis, binomial coefficient method, entropy value method, regression analysis method, etc.
[0019] Step 5: Initial hole diameter adjustment The initial lead hole diameter is adjusted according to the evaluation score of the mathematical model. When the mathematical model score is less than 4, the initial lead hole diameter is not adjusted; when the mathematical model score is greater than or equal to 4 and less than 6, the initial lead hole diameter is adjusted to 1.1-1.2 times the original diameter; when the mathematical model score is greater than or equal to 6 and less than 8, the initial lead hole diameter is adjusted to 1.3-1.4 times the original diameter; when the mathematical model score is greater than or equal to 8 and less than 10, the initial lead hole diameter is adjusted to 1.5-1.6 times the original diameter; when the mathematical model score is greater than or equal to 10, the initial lead hole diameter is adjusted to 2.0 times the original diameter; Step 6: Verification and optimization of the hole diameter adjustment results In the same construction site, use the adjusted hole diameter for construction work, use the designed jet grouting parameters for construction, and make judgments and adjustments according to the adjustment method in step five until the jet grouting diameter does not need to be adjusted.
[0020] Preferably, N times the atmospheric head pressure is determined based on field measurements, and the range of N under different geological conditions is 1.0-3.0.
[0021] Preferably, the installation position of the pore water pressure sensor 4 is as follows: from a top view, the installation positions are arranged in a circle around the designed pile diameter of the jet grouting pile, the installation positions are 2.0 times the pile diameter away from the center of the pile, and 4 installation positions are evenly arranged around each jet grouting pile; from a cross-sectional view, a pore water pressure sensor 4 is arranged at each installation position every 1.0 m along the construction depth of the jet grouting pile.
[0022] Preferably, the installation position of the inclinometer tube 5 is as follows: from a top view, the installation positions are arranged in a ring around the designed pile diameter of the jet grouting pile, the installation positions are 2.0 times the pile diameter away from the center of the pile, and 4 installation positions are evenly arranged around each jet grouting pile; from a cross-sectional view, an inclinometer tube 5 is installed at each installation position along the construction depth of the jet grouting pile, and the installation positions of the inclinometer tube 5 and the pore water pressure sensor 2 are both on the same circular ring, and the two are arranged crosswise.
[0023] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper" and "lower" and the like is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "set" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood by specific circumstances.
[0024] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention also fall within the protection scope of the present invention.
Claims
1. A test method for determining the diameter of a high-pressure jet-jet pre-drilled hole, characterized in that: The construction is carried out using jet grouting equipment, including drill pipes, drilling rigs, and monitoring equipment including pressure sensors, pore water pressure sensors, flow meters, and inclinometers. The pressure sensor is installed around the nozzle at the lower end of the drill pipe, and the pore water pressure sensor and inclinometer are installed around the designed pile diameter of the jet grouting pile. The specific test method is as follows: Step 1: Drilling hole construction The diameter of the pilot hole is set according to the diameter of the drill rod. The initial pilot hole diameter is 1.2-1.5 times the diameter of the drill rod to ensure the verticality of the pilot hole and the pilot hole depth reaches the designed depth of the jet grouting pile. Step 2: Sensor Installation Install pore water pressure sensors and inclinometers around the designed location of the jet grouting piles, set flow meters at the orifices of the lead holes, and check the access conditions of the sensors; Step 3: Spraying construction The construction is carried out according to the designed jet grouting parameters. During the construction process, the pressure sensors and flow meters are continuously measured. As the jet grouting construction proceeds, all pore water pressure sensors at the jet grouting pile construction depth and within the range of 2-3m above and below are continuously measured in real time. The changes in deep horizontal displacement are detected by the inclinometer. The detection range is the jet grouting pile construction depth and within the range of 2-8m above and below. Step 4: Monitoring data determination The suitability of the initial borehole diameter is determined based on the monitoring data of the pressure sensor, pore water pressure sensor, flow meter, and inclinometer. The four specific determination conditions are as follows: Judgment condition 1: Assume that the monitoring data of the pressure sensor is a. When a is greater than 10% of the static pressure of the mud at the depth, it is scored as 1. For every 1% increase, the score increases by 1. Judgment condition 2: Assuming that the monitoring data of the flow meter is b, when b is less than 80% of the grouting volume, it is recorded as a score of 1. Compared with 80% of the grouting volume, for every 5% decrease, the score increases by 1. Judgment condition three: Assuming that the monitoring data of the pore water pressure sensor is c, when c is greater than N times the normal pressure head pressure at the depth, it is recorded as a score of 1. Compared with N times the normal pressure head pressure, the score increases by 1 for every 0.1 times increase; Judgment condition 4: Assuming that the monitoring data of deep horizontal displacement is d, when d is greater than the initial measurement value of 30mm before rotary grouting construction, it is scored as 1. Compared with the deep horizontal displacement of 30mm, the score increases by 1 for every increase of 1mm; Conduct sensitivity analysis on the monitoring data of the four judgment conditions to determine the weight values of different monitoring data. The weights of judgment conditions one to four are A, B, C, and D respectively. Then the mathematical model of the comprehensive evaluation value is N=A*a+B*b+C*c+Dd; Step 5: Initial hole diameter adjustment The initial lead hole diameter is adjusted according to the evaluation score of the mathematical model. When the mathematical model score is less than 4, the initial lead hole diameter is not adjusted; when the mathematical model score is greater than or equal to 4 and less than 6, the initial lead hole diameter is adjusted to 1.1-1.2 times the original diameter; when the mathematical model score is greater than or equal to 6 and less than 8, the initial lead hole diameter is adjusted to 1.3-1.4 times the original diameter; when the mathematical model score is greater than or equal to 8 and less than 10, the initial lead hole diameter is adjusted to 1.5-1.6 times the original diameter; when the mathematical model score is greater than or equal to 10, the initial lead hole diameter is adjusted to 2.0 times the original diameter; Step 6: Verification and optimization of the hole diameter adjustment results In the same construction site, use the adjusted hole diameter for construction work, use the designed jet grouting parameters for construction, and make judgments and adjustments according to the adjustment method in step five until the jet grouting diameter does not need to be adjusted.
2. A test method for determining the diameter of a high-pressure jet-jet pre-drilled hole according to claim 1, characterized in that: N times the atmospheric head pressure is determined based on field measurements, and the range of N under different geological conditions is 1.0-3.
0.
3. A test method for determining the diameter of a high-pressure jet-jet pre-drilled hole according to claim 1, characterized in that: The installation positions of the pore water pressure sensors are as follows: from a top view, the installation positions are set in a circle around the designed pile diameter of the jet grouting pile, the installation positions are 0.8-2.0 times the pile diameter away from the pile center, and 2-4 installation positions are evenly set around each jet grouting pile; from a cross-sectional view, a pore water pressure sensor is set at each installation position every 0.5m-2.0m along the construction depth of the jet grouting pile.
4. A test method for determining the diameter of a high-pressure jet-jet pre-drilled hole according to claim 1, characterized in that: The installation positions of the inclinometer tubes are as follows: from a bird's eye view, installation positions are set in a circle around the designed pile diameter of the jet grouting pile. The installation positions are 0.8-2.0 times the pile diameter away from the pile center, and 2-4 installation positions are evenly set around each jet grouting pile. From a cross-sectional view, an inclinometer tube is installed at each installation position along the construction depth of the jet grouting pile. The installation positions of the inclinometer tube and the pore water pressure sensor are both on the same circular ring, and the two are arranged crosswise.