A method and system for intelligent prediction of high-pressure jet grouting pile strength

Abstract

The invention discloses an intelligent prediction method and system for the strength of a high-pressure rotary jet grouting pile. The method comprises: S0100, dividing the soil layer at the construction site of the high-pressure rotary jet grouting pile; S0200, testing the relationship curve between the strength of standard cement test blocks in different soil layers and the cement content; S0300, obtaining the EDTA titration standard curve of the return grout under different cement content; S0400, sampling the cement soil return grout at the return grout port of the high-pressure rotary jet grouting pile to determine the cement mass in the quantitative cement soil return grout sample; S0500, monitoring the on-site construction grouting flow rate and the return grout flow rate to determine the actual depth of the return grout sampling sample; S0600, measuring the density of the cement soil return grout sample; S0700, obtaining the mass of the cement soil return grout sample after drying; S0800, obtaining the cement mass in the pile body; S0900, obtaining the cement content in the pile body, and predicting the unconfined compressive strength of the pile body at the age; S1000, analyzing the sedimentation effect of the cement soil mixture to predict the pile strength within a range of 3m below the pile top. The problem of inaccurate strength prediction results has been solved.

Description

Technical Field

[0001] The present invention belongs to the field of geotechnical engineering technology, and more specifically, relates to an intelligent prediction method and system for the strength of high-pressure jet grouting piles. Background Art

[0002] High-pressure rotary jet grouting technology is an important method for foundation treatment and underground continuous wall construction. It uses high-pressure jetting of cement slurry or other curing agent mixtures to reinforce soil structure. It is widely used in building foundation engineering, dam protection, tunnel support and other fields. At present, with the advancement of engineering technology and the intelligent upgrading of construction equipment, the construction efficiency and quality control capabilities of high-pressure rotary jet grouting technology have been significantly improved. With the continuous deepening of urban infrastructure construction and the improvement of environmental protection requirements, high-pressure rotary jet grouting piles will occupy a more important position in the future foundation treatment industry due to their low construction noise, low pollution and strong adaptability. It is expected that with the development of new materials and the innovation of construction technology, this technology will play a greater role in engineering scenarios with greater depth and more complex geological conditions.

[0003] Although there are a large number of successful cases of high-pressure jet grouting piles in various industries, the traditional drilling and coring method is still used to test the strength of the pile body after the pile is formed. The core sampling test recommended by the specification generally needs to wait until the pile is 28 days old or reaches a certain age, and the pile body reaches a certain strength. If it is found that the strength of the pile body does not meet the design requirements at this time, rework will inevitably lead to a substantial increase in construction costs. At present, there is a method for predicting the strength of the pile body. Based on the results of the grouting test at the construction site, combined with the calculation and analysis of the on-site grouting construction parameters, grouting volume monitoring, grouting specific gravity, grouting moisture content, and grouting EDTA titration test data, the cement quality (or cement content) of the pile body can be accurately measured. Combined with the strength curves of the test blocks with different cement contents, the age strength of the pile body can be predicted, and the rapid prediction of the quality of the pile body can be achieved. However, this method does not take into account the delayed effect of the return slurry of the cement-soil mixture of the high-pressure jet grouting pile, that is, after the cement slurry sprayed by the high-pressure jet grouting pile machine is mixed with the soil under the ground, it takes a certain amount of time to reach the surface; for example, when the drill spray rod is constructed at a depth of 50m below the ground, the return slurry obtained at the ground return slurry port may actually be a cement-soil mixture 55m below the ground. Due to different depths and different stratum lithology, the test block strength curves used in predicting strength are different, and the final predicted pile body strength is different.

[0004] In addition, during the construction of high-pressure jet grouting piles, high-pressure cement slurry hydraulically cuts the original soil. After the original soil is broken, the original soil with different particle sizes and different particle sizes are combined with cement slurry. Before the cement-soil mixture begins to set, it will slowly settle downward under the action of gravity. According to the results of on-site coring, it was found that within 3m of the pile top, the strength of the pile body was lower than that of the rest of the pile body, and according to the designed construction parameters, it is very likely that the construction effect will not meet the requirements. The industry often adopts the super-spraying method, that is, when the drilling and spraying rod reaches the designed pile top, it continues to construct 1~2m upward. After the subsequent foundation pit is excavated to the bottom, it needs to be broken again, which increases the amount of work.

[0005] Therefore, a method and system for predicting the strength of high-pressure rotary jet grouting piles is needed. The sedimentation effect theory is introduced to consider the particle sedimentation within 3m below the pile top and its influence on the strength of the pile body. By improving the construction parameters, the strength within 3m below the pile top can be improved. There is no need for over-spraying and subsequent excavation and demolition, which can further save construction costs and promote the advancement of industry technology. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a method and system for intelligent prediction of the strength of high-pressure rotary jet grouting piles. On the basis of the existing method for predicting the strength of high-pressure rotary jet grouting piles based on the grouting test at the construction site, the delayed effect of the grouting of the cement-soil mixture of the high-pressure rotary jet grouting piles and the sedimentation effect of the cement slurry particles within 3m below the top of the pile are taken into account, thereby solving the problem of inaccurate strength prediction results.

[0007] To achieve the above objectives, according to a first aspect of an embodiment of the present invention, a method for intelligently predicting the strength of high-pressure jet grouting piles is provided, comprising the following steps:

[0008] S0100. Divide the soil layers at the construction site of high-pressure jet grouting piles according to the geological survey results;

[0009] S0200, test the relationship curve between the strength of standard cement test blocks and cement content in different soil layers;

[0010] S0300, obtain the standard curve of EDTA titration of slurry at different cement dosages through experiments;

[0011] S0400, take cement soil grouting samples at the grouting port of high-pressure jet grouting piles to determine the corresponding cement mass in the quantitative cement soil grouting samples. ;

[0012] S0500, monitoring of on-site construction shotcrete flow and return flow , determine the actual depth of the return slurry sampling sample;

[0013] S0600, measure the density of cement soil slurry samples ;

[0014] S0700, dry the quantitative cement soil slurry sample to obtain the mass of the dried cement soil slurry sample. ;

[0015] S0800, according to the parameters and curves in steps S0200-S0700, obtain the cement mass in the pile body ;

[0016] S0900, according to the cement quality in the pile , get the cement content in the pile and predict the unconfined compressive strength of the pile at a certain age;

[0017] S1000, analyze the sedimentation effect of cement-soil mixture and predict the pile strength within 3m below the pile top.

[0018] Furthermore, step S0500 specifically includes the following steps:

[0019] S0501. Determine the saturation of deep foundation reinforcement soil, that is, the volume of shotcrete is equal to the volume of return slurry, and set the shotcrete flow rate constant to , the drilling lifting speed is constant ;

[0020] S0502, measure the height of the nozzle from the ground , the diameter of the pile , The volume of the return grout from the actual grouting depth to the surface of the ground ;

[0021] S0503. Calculate the actual depth of the slurry return from the nozzle height based on the measured data , thus obtaining the actual depth of the slurry sampling sample.

[0022] Furthermore, in step S0503, the actual depth of the slurry return is the distance from the nozzle height for:

[0023] ,

[0024] in, It is the time taken for the sample to return from the actual grouting depth to the surface, specifically:

[0025] ,

[0026] Among them, the volume of the return slurry sample from the actual grouting depth to the surface Specifically:

[0027] ,

[0028] Then the actual depth of the slurry return from the nozzle height is obtained by combining for:

[0029] .

[0030] Furthermore, the actual depth of the slurry return is proportional to the nozzle height. The buried depth of the pile represented by the back-slurry sampling sample is: .

[0031] Furthermore, step S1000 specifically includes the following steps:

[0032] S1001. Conduct theoretical analysis and establish a particle size distribution and compactness sedimentation model for high-pressure jet grouting cement-soil mixtures to determine the apparent cement slurry pore structure and strength.

[0033] S1002. Use indoor tests to verify the theoretical derivation above and study the data related to soil particle size and high-pressure jet grouting pile strength, including training sets and test sets;

[0034] S1003, normalizing the data of cement soil particle size and pile strength to meet the input requirements of the neural network;

[0035] S1004, establish a BP neural network model, and set the corresponding number of hidden layer nodes according to the data situation;

[0036] S1005, using the training set data to train the BP neural network model, and adjusting the network parameters until a predetermined error target is reached;

[0037] S1006. Calculation of relative error and determination coefficient of the particle size distribution and compactness sedimentation model of high-pressure jet grouting pile cement soil mixture , evaluate the predictive performance of the model;

[0038] S1007. Predict the strength of the pile within 3m below the pile top and adjust the construction parameters to ensure that the pile strength meets the design requirements.

[0039] Furthermore, in step S1001, the particle size distribution compactness deposition model of the high-pressure jet grouting pile cement soil mixture is specifically:

[0040] ,

[0041] in, Particle size The cumulative sieve residue fraction, is the soil particle size, is the particle size of the smallest particle in the system, is the size of the largest particle in the system, is the distribution modulus.

[0042] Furthermore, in step S1007, when predicting the strength of the pile within 3 m below the pile top, the influence of the hydration reaction rate and heat release on the pile strength is introduced. Specifically:

[0043] ;

[0044] in, and is a constant related to the type of cement,

[0045] is the influencing factor related to porosity,

[0046] is the initial porosity over time,

[0047] is the function of heat release rate on porosity change,

[0048] is the heat release rate,

[0049] is the function of the heat release rate on the pile strength,

[0050] is the temperature correction factor,

[0051] For time,

[0052] is the reaction rate constant,

[0053] is the exponential factor,

[0054] The degree of hydration.

[0055] Furthermore, the heat release rate for:

[0056] ,

[0057] in, For the cumulative heat release,

[0058] is the maximum heat release,

[0059] is the degree of hydration, .

[0060] Furthermore, the temperature correction factor for:

[0061] ,

[0062] in, is a constant,

[0063] is the activation energy,

[0064] is the gas constant,

[0065] For temperature.

[0066] According to a second aspect of an embodiment of the present invention, there is provided a high-pressure jet grouting pile strength intelligent prediction system, comprising:

[0067] Survey module: used to divide the soil layers at the construction site of high-pressure jet grouting piles according to geological survey results;

[0068] Test module: used to test the relationship curve between the strength and cement content of standard cement test blocks in different soil layers;

[0069] Experimental module: used to obtain the EDTA titration standard curve of slurry at different cement dosages through experiments;

[0070] Sampling module: used to sample cement soil slurry at the slurry port of high-pressure jet grouting piles and determine the corresponding cement mass in the quantitative cement soil slurry sample. ;

[0071] Monitoring module: used to monitor the spraying flow rate during on-site construction and return flow , determine the actual depth of the return slurry sampling sample;

[0072] The first measurement module: used to measure the density of cement soil slurry samples ;

[0073] Drying module: used to dry the quantitative cement soil slurry sample and obtain the quality of the dried cement soil slurry sample. ;

[0074] The second measurement module is used to obtain the cement quality in the pile body according to the parameters and curves in steps S0200-S0700. ;

[0075] The first prediction module is used to predict the quality of cement in the pile. , get the cement content in the pile and predict the unconfined compressive strength of the pile at a certain age;

[0076] The second prediction module is used to analyze the sedimentation effect of cement-soil mixture and predict the pile strength within 3m below the pile top.

[0077] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0078] 1. The intelligent prediction method for the pile strength of high-pressure rotary jet grouting piles of the present invention, based on the existing high-pressure rotary jet grouting pile strength prediction method based on the construction site grouting test, takes into account the delayed effect of the grouting of the cement-soil mixture of the high-pressure rotary jet grouting piles and the sedimentation effect of the cement slurry particles within 3m below the pile top, thereby solving the problem of inaccurate strength prediction results.

[0079] 2. The intelligent prediction method for the strength of high-pressure rotary jet grouting piles of the present invention overcomes the deficiency of the traditional coring method that the quality of high-pressure rotary jet grouting piles can only be detected after the age is reached. The prediction can be carried out during the construction of high-pressure rotary jet grouting piles. When problems are found, the construction parameters can be adjusted in time to ensure the construction quality.

[0080] 3. The intelligent prediction method for the pile strength of high-pressure rotary jet grouting piles of the present invention groups and normalizes the soil particle size and the high-pressure rotary jet grouting pile strength data, creates a BP neural network, and performs grid training, which significantly improves the accurate prediction of the pile strength of high-pressure rotary jet grouting piles. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 A schematic diagram of a process for intelligently predicting the strength of a high-pressure jet grouting pile according to an embodiment of the present invention;

[0082] Figure 2 This is a specific flow chart of step S0200 of a method for intelligently predicting the strength of high-pressure jet grouting piles according to an embodiment of the present invention;

[0083] Figure 3 This is a specific flow chart of step S0400 of a method for intelligently predicting the strength of high-pressure jet grouting piles according to an embodiment of the present invention;

[0084] Figure 4 This is a specific flow chart of step S0500 of a method for intelligently predicting the strength of high-pressure jet grouting piles according to an embodiment of the present invention;

[0085] Figure 5 This is a specific flow chart of step S1000 of a method for intelligently predicting the strength of high-pressure jet grouting piles according to an embodiment of the present invention. DETAILED DESCRIPTION

[0086] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0087] Example 1

[0088] like Figure 1 The embodiment of the present invention provides a method for intelligently predicting the strength of high-pressure jet grouting piles, which specifically includes the following steps:

[0089] S0100. Conduct geological survey on the construction site of the high-pressure jet grouting column, and divide the high-pressure jet grouting pile into layers in depth according to the surveyed strata results;

[0090] S0200. Take original soil samples on site, make standard cement soil test blocks with different soil layers and different cement content, and test the relationship curve between the strength of different soil layers at 28 days and cement content;

[0091] S0300. Using original soil samples from different soil layers, an improved EDTA titration test was carried out to obtain the EDTA titration standard curve of the slurry at different cement dosages.

[0092] S0400, take cement soil grouting samples at the grouting port of high-pressure jet grouting piles, and perform EDTA titration of the cement content in the grouting on site to determine the corresponding cement mass in the quantitative cement soil grouting sample. ;

[0093] S0500, monitoring of on-site construction shotcrete flow and return flow , carry out the analysis of the delayed effect of the slurry return, record the depth of the drill nozzle during the slurry return sampling, and determine the actual depth of the slurry return sampling sample through theoretical deduction;

[0094] S0600, conduct on-site slurry specific gravity test to measure the density of cement soil slurry samples ;

[0095] S0700, dry the quantitative cement soil slurry sample to obtain the mass of the dried cement soil slurry sample. ;

[0096] S0800, according to the parameters and curves in steps S0200-S0700, obtain the cement mass in the pile body ;

[0097] S0900, according to the cement quality in the pile , obtain the cement content in the pile body, consult the strength test block configuration and strength test curve of different cement content obtained in step S0200, predict the unconfined compressive strength of the pile body at the age, and determine whether it meets the design requirements;

[0098] S1000. Identify the strata within 3m below the pile top, analyze the sedimentation effect of cement-soil mixture, evaluate the relationship between the particle composition after initial setting and the pile strength, and predict the pile strength within 3m below the pile top.

[0099] like Figure 2 As shown, step S0200 specifically includes the following steps:

[0100] S0201. Before the construction of high-pressure jet grouting piles on site, drill and take original soil samples, take original soil samples representing each soil layer, and prepare cement-soil mixture according to the designed cement content ±20%, with 5% as the change value, and the water-cement ratio in the construction parameters;

[0101] S0202. After each soil layer and each cement-soil mixture is stirred evenly, it is placed into at least two triple plastic mortar test molds (size 70.7mm×70.7mm×70.7mm), vibrated evenly with a vibrating rod, and then placed in a standard curing room for curing to obtain multiple test blocks;

[0102] S0203. After reaching the age of 28 days, use a pressure testing machine to test the strength of the test blocks. After taking the average value of the strength data, draw a relationship curve between the strength of each soil layer at 28 days and the cement content.

[0103] In step S0300, 300g of undisturbed soil is taken for titration test, and the disodium EDTA consumed is within 3mL, while the EDTA consumption of 300g of pure cement is above 250mL, so the calcium ions that undergo chemical reaction during titration are mainly present in cement. When the mass of pure cement powder is within 40g, the standard curve is linear, and the corresponding cement mass can be calculated by back-calculating the EDTA consumption. For this reason, when configuring the on-site standard curve, the mass of the cement-soil mixture is determined to be 100g, and the cement powder mass is calculated by back-calculation according to the on-site construction parameters. At this time, the mass of the cement powder is within 40g.

[0104] The specific steps include:

[0105] (1) Preparation of test instruments and equipment

[0106] 1) Burette (acid type): 50mL, 1 piece.

[0107] 2) Titration stand: 1 piece.

[0108] 3) Burette clamp: 1 pc.

[0109] 4) Large-bellied pipettes: 10mL, 50mL, 10 pieces.

[0110] 5) Conical flask (i.e. triangular flask): 200mL, 20 pcs.

[0111] 6) Beaker: 2000mL (or 1000mL), 1 pc; 300mL, 10 pcs.

[0112] 7) Volumetric flask: 1000mL, 1 piece.

[0113] 8) Enamel cup: capacity greater than 1200mL, 10 pieces.

[0114] 9) Stainless steel rods (or thick glass rods): 10 pieces.

[0115] 10) Measuring cylinder: 100mL and 5mL, 1 each; 50mL, 2 pcs.

[0116] 11) Brown wide-mouth bottle: 60mL, 1 piece (for calcium red indicator).

[0117] 12) Electronic balance: range not less than 1500g, sensitivity 0.01g.

[0118] 13) Stopwatch: 1 piece.

[0119] 14) Surface dish: Φ9cm, 10 pieces.

[0120] 15) Mortar: Φ12~13cm, 1 piece.

[0121] 16) Ear cleaning bulb: 1 pc.

[0122] 17) Precision test paper: pH 12~14.

[0123] 18) Polyethylene barrels: 20L (filled with distilled water, ammonium chloride and disodium EDTA standard solution), 3 pieces; 5L (filled with sodium hydroxide), 1 piece; 5L (wide-mouth barrel), 10 pieces.

[0124] 19) Brush, scouring powder, suction tube, plastic spoon, special pencil, centimeter paper.

[0125] 20) Washing bottle (plastic): 500mL, 1 piece.

[0126] (2) Experimental drugs

[0127] 1) 0.1 mol / m 3Disodium ethylenediaminetetraacetate (Disodium EDTA) standard solution (abbreviated as Disodium EDTA standard solution); accurately weigh 37.23g of disodium EDTA (analytical grade), dissolve it in 40-50°C carbon dioxide-free distilled water, and after it is completely dissolved and cooled to room temperature, dilute to 1000mL. If there are many test samples, you can weigh them in multiples and dilute to a multiple of 1000mL. When not in use, it needs to be stored in a closed environment at room temperature and avoid direct sunlight.

[0128] 2) 10% ammonium chloride (NH4Cl) solution: Place 500g of ammonium chloride (analytical or chemically pure) in a 10L polyethylene barrel, add 4500mL of distilled water, and shake thoroughly to dissolve the ammonium chloride completely. You can also prepare it in batches in a 1000mL beaker, then pour it into a plastic barrel and shake well. To avoid a decrease in the concentration of the ammonium chloride solution, try to use the ammonium chloride solution prepared on the same day.

[0129] 3) 1.8% sodium hydroxide (containing triethanolamine) solution: Use an electronic balance to weigh 18g of sodium hydroxide (NaOH) (analytical grade), put it into a clean and dry 1000mL beaker, add 1000mL of distilled water to dissolve it completely, after the solution cools to room temperature, add 2mL of triethanolamine (analytical grade), stir well and store in a plastic bucket.

[0130] 4) Calcium red indicator: 0.2g of calcium reagent sodium carboxylate (molecular formula C 21 H 13 N2NaO7S, molecular weight 460.39) was mixed with 20g of potassium sulfate which had been previously dried in an oven at 105°C for 1h. Put them together in a mortar, grind them into a very fine powder, and store them in a brown wide-mouth bottle to prevent moisture absorption.

[0131] (3) Standard curve configuration

[0132] 1) Sampling and testing of undisturbed soil: Before construction, drill holes and take cores at the construction site. The soil samples within the scope of the pile body to be constructed are divided according to the strata, and the natural moisture content of each layer of the undisturbed soil is tested. The soil is classified and placed into sampling buckets (soil from different strata is placed in different sampling buckets), sealed and stored in a cool place;

[0133] 2) Assuming that the designed cement content is A%, and the water-cement ratio is the water-cement ratio B in the design construction parameters, prepare a mixture of cement + water + undisturbed soil according to the designed cement content A±20%, with a change value of 5%. After stirring evenly, take 100g of each mixture and put it into the corresponding enamel cup marked with the designed cement content;

[0134] 3) Add 600 mL of 10% ammonium chloride solution to an enamel cup and stir with a glass rod for 3 minutes (110-120 times per minute). After stirring, let it settle for 10 minutes, then transfer the upper clear liquid to a 300 mL beaker, stir well, and cover with a watch glass for testing;

[0135] 4) Use a pipette to draw 10.0mL of the upper layer (1-2cm below the liquid surface) of the suspension into a 200mL conical flask, use a measuring tube to measure 50mL of 1.8% sodium hydroxide (containing triethanolamine) solution and pour it into the conical flask. At this time, the pH value of the solution is 12.5-13.0 (can be tested with pH12-14 precision test paper), then add calcium red indicator (mass is about 0.2g), shake well, and the solution will be rose red. Record the volume V1 of the disodium EDTA standard solution in the burette, then titrate with the disodium EDTA standard solution, shake well while titrating, and observe the color of the solution carefully; when the color of the solution turns purple, slow down the titration speed and shake well; until the pure blue is the end point, record the volume V2 of the disodium EDTA standard solution in the burette (in mL, read to 0.1mL). Calculate V1-V2, which is the consumption of the disodium EDTA standard solution;

[0136] 5) Test the samples in the other sampling barrels in the same way and record the consumption of the respective disodium EDTA standard solutions;

[0137] 6) Use the average consumption (mL) of disodium EDTA standard solution of the same cement material as the ordinate and the cement content as the abscissa to draw a graph. If the cement batch is changed during construction, the standard curve must be redone.

[0138] like Figure 3 As shown, step S0400 specifically includes the following steps:

[0139] S0401. Cement slurry sampling: Take cement soil slurry per meter at the slurry outlet of high-pressure jet grouting piles. Pay attention to the representativeness of the sampling and select fresh undiluted cement soil slurry samples;

[0140] S0402. After the slurry is stirred evenly, 100 g is weighed and put into an enamel cup, and then an EDTA titration operation is performed. According to the standard curve drawn in step S0300 and the consumption of disodium EDTA standard solution, the corresponding cement mass in 100 g of cement soil slurry sample is determined.

[0141] In step S0402, since the consumption of disodium EDTA standard solution brought by pure soil in 100g cement soil slurry sample is negligible relative to the consumption of cement, the consumption of disodium EDTA standard solution can be considered to be consumed by cement. After checking the standard curve, the quality of cement can be determined.

[0142] like Figure 4 As shown, step S0500 specifically includes the following steps:

[0143] S0501. Determine the saturation of deep foundation reinforcement soil, that is, the volume of shotcrete is equal to the volume of return slurry, and set the shotcrete flow rate constant to , the drilling lifting speed is constant ;

[0144] S0502, measure the height of the nozzle from the ground , the diameter of the pile , The volume of the return grout from the actual grouting depth to the surface of the ground ;

[0145] S0503. Calculate the actual depth of the slurry return from the nozzle height based on the measured data , thus obtaining the actual depth of the slurry sampling sample.

[0146] In step S0503, the actual depth of the slurry return is for:

[0147] ,

[0148] in, It is the time taken for the sample to return from the actual grouting depth to the surface, specifically:

[0149] ,

[0150] Among them, the volume of the return slurry sample from the actual grouting depth to the surface Specifically:

[0151] ,

[0152] Then the actual depth of the slurry return from the nozzle height is obtained by combining for:

[0153] .

[0154] The actual depth of the slurry backflow is the distance from the nozzle height The buried depth of the pile represented by the back-slurry sampling sample is: .

[0155] Step S0800 specifically includes the following steps:

[0156] S0801. Combined with the EDTA titration test of cement content in the field, determine the mass of cement dry powder in every 100g of cement soil slurry mixture. m1. The product of cement hydration is (1+Y%) m 1 (A large number of indoor tests have shown that the mass of cement will increase during hydration reaction. Assuming that the increase percentage is Y%, after drying, there will be Y% of the cement mass of water absorbed by the cement and cannot be dried. From the existing technical data, the increase percentage can be taken as 25%). The mass after drying is m 2, then the mass of soil particles is m 3= m 2-(1+Y%) m 1. Moisture content of original soil w It is known that the mass of the original soil in 100g of cement soil slurry is (1+ w ) m 3. Quality of added water m 4= 100- m 1-(1+ w ) m 3. Cement content is m 1 / (1+ w ) m 3;

[0157] S0802. Assume that the original soil is saturated soil and the voids are filled with water;

[0158] S0803, according to the lifting speed of the shotcrete rod v (cm / min), calculate the time required to lift the shotcrete rod 1 meter t= 100 / V ( min );

[0159] S0804. Assuming that the pile body is uniform within each meter, the cement slurry spraying flow rate measured in step 4 is Q ( L / min), calculate the cumulative amount of cement slurry sprayed per meter V 1= Q / 10× v (m 3 );

[0160] S0805. According to step S0400, the amount of cement slurry mixture returned per meter is obtained as follows: V 2. When considering the overall return slurry volume, it is necessary to consider the volume of cement slurry in the return slurry channel. Assuming that the diameter of the return slurry hole is d 1 and the depth of the return hole h , calculate the volume of cement slurry mixture in the return hole V 3 = 0.25 × 3.14 × d 1× d 1× h The total slurry volume is V返浆 = V 2+ V 3;

[0161] S0806. According to the process test before large-scale construction, the pile diameter is designed and verified according to the design construction parameters. d 2. Calculate the volume of pile per meter V 4=0.25×3.14× d 2× d 2;

[0162] S0807. Calculate the density of cement slurry based on the water-cement ratio B of cement slurry. , then the mass of cement powder per meter of shotcrete is ;

[0163] S0808, per meter of slurry, according to the measured slurry density , back slurry volume V 2. Calculate the total mass of slurry per meter ;

[0164] S0809. Calculate the mass of undisturbed soil per meter of undisturbed soil based on the mass percentage of undisturbed soil per 100g of slurry in the titration test. M 3= m 6×(1+ w ) m 3 / 100, the mass of the original soil left in the pile is ;

[0165] S0810. Calculate the cement mass per meter of return slurry based on the percentage of cement mass per 100g of return slurry in the titration test. M 5= m 6× m 1 / 100, the mass of cement remaining in the pile is calculated to be M 6= m 5- M 5。

[0166] like Figure 5 As shown, step S1000 specifically includes the following steps:

[0167] S1001. Conduct theoretical analysis and establish a particle size distribution and compactness sedimentation model for high-pressure jet grouting cement-soil mixtures to determine the apparent cement slurry pore structure and strength.

[0168] S1002. Use indoor tests to verify the theoretical derivation above and study the data related to soil particle size and high-pressure jet grouting pile strength, including training sets and test sets;

[0169] S1003, normalizing the data of cement soil particle size and pile strength to meet the input requirements of the neural network;

[0170] S1004, establish a BP neural network model, and set the corresponding number of hidden layer nodes according to the data situation;

[0171] S1005, using the training set data to train the BP neural network model, and adjusting the network parameters until a predetermined error target is reached;

[0172] S1006. Calculation of relative error and determination coefficient of the particle size distribution and compactness sedimentation model of high-pressure jet grouting pile cement soil mixture , evaluate the predictive performance of the model;

[0173] S1007. Predict the strength of the pile within 3m below the pile top and adjust the construction parameters to ensure that the pile strength meets the design requirements.

[0174] Furthermore, in step S1001, the particle size distribution compactness deposition model of the high-pressure jet grouting pile cement soil mixture is specifically:

[0175] ,

[0176] in, Particle size The cumulative sieve residue fraction, is the soil particle size, is the particle size of the smallest particle in the system, is the size of the largest particle in the system, is the distribution modulus.

[0177] Furthermore, in step S1007, when predicting the strength of the pile within 3 m below the pile top, the influence of the hydration reaction rate and heat release on the pile strength is introduced. Specifically:

[0178] ;

[0179] in, and is a constant related to the type of cement,

[0180] is the influencing factor related to porosity,

[0181] is the initial porosity over time,

[0182] is the function of heat release rate on porosity change,

[0183] is the heat release rate,

[0184] is the function of the heat release rate on the pile strength,

[0185] is the temperature correction factor,

[0186] For time,

[0187] is the reaction rate constant,

[0188] is the exponential factor,

[0189] The degree of hydration.

[0190] Furthermore, the heat release rate for:

[0191] ,

[0192] in, For the cumulative heat release,

[0193] is the maximum heat release,

[0194] is the degree of hydration, .

[0195] Furthermore, the temperature correction factor for:

[0196] ,

[0197] in, is a constant,

[0198] is the activation energy,

[0199] is the gas constant,

[0200] For temperature.

[0201] The effect of heat release rate on porosity change Specifically:

[0202] ,

[0203] in, for The porosity change at extremely low levels,

[0204] is the maximum porosity change,

[0205] is the steepness control coefficient of the curve,

[0206] for The heat release rate at which the porosity change reaches half.

[0207] The effect of heat release rate on pile strength Specifically:

[0208] ,

[0209] in, and is a constant determined based on experimental data.

[0210] According to a second aspect of an embodiment of the present invention, there is provided a high-pressure jet grouting pile strength intelligent prediction system, comprising:

[0211] Survey module: used to divide the soil layers at the construction site of high-pressure jet grouting piles according to geological survey results;

[0212] Test module: used to test the relationship curve between the strength and cement content of standard cement test blocks in different soil layers;

[0213] Experimental module: used to obtain the EDTA titration standard curve of slurry at different cement dosages through experiments;

[0214] Sampling module: used to sample cement soil slurry at the slurry port of high-pressure jet grouting piles and determine the corresponding cement mass in the quantitative cement soil slurry sample. ;

[0215] Monitoring module: used to monitor the spraying flow rate during on-site construction and return flow , determine the actual depth of the return slurry sampling sample;

[0216] The first measurement module: used to measure the density of cement soil slurry samples ;

[0217] Drying module: used to dry the quantitative cement soil slurry sample and obtain the quality of the dried cement soil slurry sample. ;

[0218] The second measurement module is used to obtain the cement quality in the pile body according to the parameters and curves in steps S0200-S0700. ;

[0219] The first prediction module is used to predict the quality of cement in the pile. , get the cement content in the pile and predict the unconfined compressive strength of the pile at a certain age;

[0220] The second prediction module is used to analyze the sedimentation effect of cement-soil mixture and predict the pile strength within 3m below the pile top.

[0221] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for intelligently predicting the strength of high-pressure jet grouting piles, characterized in that: The following steps are involved: S0100. Divide the soil layers at the construction site of high-pressure jet grouting piles according to the geological survey results; S0200, test the relationship curve between the strength of standard cement test blocks and cement content in different soil layers; S0300, obtain the EDTA titration standard curve of slurry at different cement dosages through experiments; S0400, take cement soil grouting samples at the grouting port of high-pressure jet grouting piles to determine the corresponding cement mass in the quantitative cement soil grouting samples. ; S0500, monitoring of on-site construction shotcrete flow and return flow , determine the actual depth of the return slurry sampling sample; S0600, measure the density of cement soil slurry samples ; S0700, dry the quantitative cement soil slurry sample to obtain the mass of the dried cement soil slurry sample. ; S0800, according to the parameters and curves in steps S0200-S0700, obtain the cement mass in the pile body ; S0900, according to the cement quality in the pile , get the cement content in the pile and predict the unconfined compressive strength of the pile at a certain age; S1000, analyze the sedimentation effect of cement-soil mixture and predict the pile strength within 3m below the pile top; Step S0500 specifically includes the following steps: S0501. Determine the saturation of deep foundation reinforcement soil, that is, the volume of shotcrete is equal to the volume of return slurry, and set the shotcrete flow rate constant to , the drilling lifting speed is constant ; S0502, measure the height of the nozzle from the ground , the diameter of the pile , The volume of the return grout from the actual grouting depth to the surface of the ground ; S0503. Calculate the actual depth of the slurry return from the nozzle height based on the measured data , thus obtaining the actual depth of the return slurry sampling sample; In step S0503, the actual depth of the slurry return is for: ， in, It is the time taken for the sample to return from the actual grouting depth to the surface, specifically: ， Among them, the volume of the return slurry sample from the actual grouting depth to the surface Specifically: ， Then the actual depth of the slurry return from the nozzle height is obtained by combining for: ； The actual depth of the slurry backflow is the distance from the nozzle height The buried depth of the pile represented by the back-slurry sampling sample is: .

2. The intelligent prediction method for the strength of high-pressure jet grouting piles according to claim 1 is characterized in that: In step S1000, the following steps are specifically included: S1001. Conduct theoretical analysis and establish a sedimentation model for the particle size distribution and compactness of cement-soil mixtures of high-pressure jet grouting piles for the apparent pore structure and strength of cement slurry; S1002. Use indoor tests to verify the theoretical derivation above and study the data related to soil particle size and high-pressure jet grouting pile strength, including training sets and test sets; S1003, normalizing the data of cement soil particle size and pile strength to meet the input requirements of the neural network; S1004, establish a BP neural network model, and set the corresponding number of hidden layer nodes according to the data situation; S1005, using the training set data to train the BP neural network model, and adjusting the network parameters until a predetermined error target is reached; S1006. Calculation of relative error and determination coefficient of the particle size distribution and compactness sedimentation model of high-pressure jet grouting pile cement soil mixture , evaluate the predictive performance of the model; S1007. Predict the strength of the pile within 3m below the pile top and adjust the construction parameters to ensure that the pile strength meets the design requirements.

3. The intelligent prediction method for the strength of high-pressure jet grouting piles according to claim 2 is characterized in that: In step S1001, the particle size distribution compactness deposition model of the high-pressure jet grouting pile cement soil mixture is specifically: ， in, Particle size The cumulative sieve residue fraction, is the soil particle size, is the particle size of the smallest particle in the system, is the size of the largest particle in the system, is the distribution modulus.

4. The intelligent prediction method for the strength of high-pressure jet grouting piles according to claim 3 is characterized in that: In step S1007, when predicting the strength of the pile within 3 m below the pile top, the influence of the hydration reaction rate and heat release on the pile strength is introduced. Specifically: ； in, and is a constant related to the type of cement, is the influencing factor related to porosity, is the initial porosity over time, is the function of heat release rate on porosity change, is the heat release rate, is the function of the heat release rate on the pile strength, is the temperature correction factor, For time, is the reaction rate constant, is the exponential factor, The degree of hydration.

5. The intelligent prediction method for the strength of high-pressure jet grouting piles according to claim 4 is characterized in that: The heat release rate for: ， in, For the cumulative heat release, is the maximum heat release, is the degree of hydration, .

6. The intelligent prediction method for the strength of high-pressure jet grouting piles according to claim 5 is characterized in that: The temperature correction factor for: ， in, is a constant, is the activation energy, is the gas constant, For temperature.

7. A high-pressure jet grouting pile strength intelligent prediction system, used to implement a high-pressure jet grouting pile strength intelligent prediction method as claimed in any one of claims 1 to 6, characterized in that: include: Survey module: used to divide the soil layers at the construction site of high-pressure jet grouting piles according to geological survey results; Test module: used to test the relationship curve between the strength and cement content of standard cement test blocks in different soil layers; Experimental module: used to obtain the EDTA titration standard curve of slurry at different cement dosages through experiments; Sampling module: used to sample cement soil slurry at the slurry port of high-pressure jet grouting piles and determine the corresponding cement mass in the quantitative cement soil slurry sample. ; Monitoring module: used to monitor the spraying flow rate during on-site construction and return flow , determine the actual depth of the return slurry sampling sample; The first measurement module: used to measure the density of cement soil slurry samples ; Drying module: used to dry the quantitative cement soil slurry sample and obtain the quality of the dried cement soil slurry sample. ; The second measurement module is used to obtain the cement quality in the pile body according to the parameters and curves in steps S0200-S0700. ; The first prediction module is used to predict the quality of cement in the pile. , get the cement content in the pile and predict the unconfined compressive strength of the pile at a certain age; The second prediction module is used to analyze the sedimentation effect of cement-soil mixture and predict the pile strength within 3m below the pile top.

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