Seek the construction scheme of high-pressure jet grouting pile?

High-pressure jet grouting pile is to inject cement slurry into the soil layer by using high-pressure rotary nozzle and mix it with soil to form continuous overlapping cement and solid. The construction occupies less land, has little vibration and low noise, but it is easy to pollute the environment and has high cost, so it is not suitable for special soil that cannot be solidified by shotcrete.

1. Scope of application (1) The high-pressure jet grouting method is suitable for treating silt, muddy soil, flowing plastic, soft plastic or plastic cohesive soil, silty soil, sandy soil, loess, plain fill and crushed stone soil. (2) When the soil contains a large number of large-size stones, hard clay, a large number of plant roots or too much organic matter, the applicability of silt, peat soil and collapsible loess foundation reinforcement should be determined according to the field test results. Its applicability and technical parameters should be determined by high-pressure jet grouting test. (3) High-pressure jet grouting method should be used with caution in foundation projects with excessive groundwater velocity and large water inflow, for the stratum with pebble, block and boulder skeleton structure in bedrock and gravel soil. (4) The high-pressure jet grouting method can be used for foundation reinforcement of existing buildings and new buildings, water-stop curtain of deep foundation pit, retaining soil or water on slopes, foundation pit bottom reinforcement, prevention of piping and uplift, plugging and reinforcement of underground large-diameter pipelines, soil layer reinforcement or waterproofing of subway projects, reservoir dams, seawalls, river dikes, dam foundation seepage prevention and dam interception of underground reservoirs. 2. Basic provisions (1) The design and construction of high-pressure jet grouting foundation engineering should be adapted to local conditions, and the factors such as foundation type and nature, groundwater conditions, superstructure form, load, site environment, construction equipment performance, etc. should be comprehensively considered to ensure the engineering quality. (2) The grouting forms of high-pressure jet grouting method are divided into three categories: rotary jet grouting, swing jet grouting and fixed jet grouting. According to the engineering needs and equipment conditions, single pipe method, double pipe method and three pipe method can be used respectively, and the three-dimensional shape can be divided into cylindrical, fan-shaped block, wall and plate. (3) High-pressure jet grouting, fixed jet grouting, swing jet grouting, large-angle swing jet grouting and rotary jet grouting are suitable for loose stratum, gravel stratum and bedrock eluvial layer with particle sizes not more than 20mm, 60mm and 100mm respectively. (4) When formulating the high-pressure jet grouting scheme, we should master the engineering geology, hydrogeology and architectural structure design data of the site. For existing buildings, relevant historical and current information, adjacent buildings and underground buried objects should be collected. (5) After the scheme of high-pressure jet grouting is determined, field test and pilot construction should be carried out in combination with the engineering situation, or the construction parameters and technology should be determined according to the engineering experience. (6) The test site of high-pressure jet grouting should be selected in the representative section of the whole project, and the test can reflect the reinforcement or anti-seepage effect of high-pressure jet grouting on foundation treatment engineering. 6.9.2 Construction preparation: 1. Requirements for re-inspection of materials, finished products, semi-finished products and components (1) The grouting materials used in the high-pressure jet grouting method are mainly cement and water, and a small amount of additives are added when necessary. (2) The variety and label of cement used in high-pressure jet grouting should be determined according to the environment and engineering needs. Generally, ordinary portland cement should be adopted, and its strength grade should not be lower than 32.5. When grouting with other cement, design permission shall be obtained. (3) Cement for grouting shall comply with the provisions of Portland Cement and Ordinary Portland Cement GB175-1999. (4) Cement for high-pressure jet grouting must meet the quality standards, and be strictly moisture-proof to shorten the storage time. Sampling inspection shall be conducted during construction, and expired and caked cement shall not be used. (5) The water used for mixing cement slurry shall conform to the Standard for Concrete Mixing Water (JGJG63-89). (6) High pressure jet grouting generally adopts pure cement slurry. Under special geological conditions or special requirements, according to the engineering needs, different types of grout can be adopted through field grouting test. Such as cement mortar. (7) Additives such as fine sand, fly ash, early strength agent, accelerator and water glass can be added to the cement slurry as required. 2. Main construction machinery and equipment (1) High-pressure jet grouting construction machinery and equipment include domestic equipment and imported equipment. The main equipment used in the construction are: geological pore-forming equipment, stirring pulping equipment, gas supply, water supply and slurry supply equipment, jet grouting equipment and control measurement and testing equipment. 1) Geological pore-forming equipment: geological drilling rig, down-the-hole drilling rig, impact rotary drilling rig, water well grinding disc drilling rig, vibroflotation equipment, etc. 2) Mixing pulping equipment: mixing irrigation machine, mixer, mortar mixer, slurry mixer, high-speed pulping equipment, etc. 3) Gas supply, water supply and pulp supply equipment: air compressor, high-pressure water pump, high-pressure pulp pump, medium-pressure pulp pump, grouting pump, etc. 4) Jet grouting equipment: high-pressure rotary jet machine, rotary swing fixed jet lifting device, jet pipe nozzle device, etc. 5) Control measuring and test equipment: measuring instruments, measuring rulers, level meters, inclinometers, densimeters, pressure gauges, flowmeters, etc. (2) Select the construction machinery and equipment according to the engineering needs and site geological conditions. 3. The construction site (operating conditions) requires (1) leveling the site, removing movable obstacles on the ground and underground, and taking measures to prevent the construction machinery from becoming unstable. (2) Set up temporary construction facilities, such as water supply, power supply, roads, temporary houses, workstations, material warehouses, etc. (3) The construction platform should be smooth and solid, and special pipes and lines for wind, water and electricity should be set. (4) The construction unit shall formulate environmental protection measures, and the construction site shall be equipped with wastewater and waste slurry treatment and recovery systems. (5) Mud drainage ditch and mud collection pit should be set up on the construction site for excavation. (6) Before construction, the positions of underground pipelines and structures on the site should be measured. (7) Check and properly protect the baseline, leveling points, axis pile position and design hole position. (8) Mechanical assembly and debugging shall comply with the provisions of safety operation procedures. (9) Safety signs and safety protection measures shall be set before construction. 4. Technical preparation (1) Before construction, the construction, design and supervision units shall make technical disclosure to the construction unit and provide the following documents and materials: 1) Engineering design report and foundation and foundation construction drawing. 2) Engineering geological and hydrogeological data of the construction site. 3) Information of ground high-voltage lines, telephone lines and various pipelines on the construction site. 4) Information about underground pipelines and existing underground structures on the construction site. 5) Necessary load test and other relevant test data. 6) Construction technical requirements, including quality standards and inspection methods. 7) Complete relevant test reports before construction. 8) Standards and related documents used in construction. 9) Four-way and One-leveling survey datum data of the construction site. (2) Before construction, the construction unit shall do the following work: 1) Prepare the construction organization design. 2) Establish a quality assurance system. 3) Formulate safety operation procedures. 4) Formulate labor protection and civilized construction measures. 5) Organize construction personnel to carry out technical disclosure and training. 6) Organize the study of national safety production laws and regulations. 7) Various forms used in the construction records shall meet the specification requirements. 6.9.3 Construction technology 1. Construction technology of high-pressure jet grouting (1) The construction technology of high-pressure jet grouting should be carried out in rows of holes first, and each row of holes should be constructed in sequence. When single-hole grouting has no influence on adjacent holes, it can be constructed in turn. Construction of single-pipe independent jet grouting pile without casing in turn. (2) High-pressure jet grouting rotates, swings and fixes the jet structure, and sequentially constructs socket, lap, connection and "welding" holes. 2. Operation flow (1) Measuring and setting-out: Measure the setting-out construction axis according to the design and construction drawing and coordinate network points. (2) Determine the hole position: determine the hole position on the construction axis, code the pile number, hole number and serial number, and measure the ground elevation of each orifice according to the datum point. (3) Drilling with drilling rig: rotary drilling with mud wall protection, impact casing drilling and impact rotary casing drilling can be used. 1) The main drill pipe of the drilling rig should be aligned with the hole position, and the horizontal and vertical axes of the fuselage should be measured with a level meter. The drilling rig should be firmly and firmly padded. 2) The aperture should be 20 ~ 50 mm larger than the outside diameter of grouting pipe, so as to ensure normal slurry return and bubbling during grouting. 3) Before spudding, the technical team of the project department shall issue a spudding notice and report it to the supervision engineer for approval before spudding. 4) Measure the horizontal and vertical axes of the fuselage 1 time with a level every 5m to ensure the verticality of the borehole. 5) In order to prevent hole collapse during drilling, mud is used to protect the wall. The bulk density of clay mud is generally1.1~1.25g/cm3. 6) Pay attention to formation changes at any time during drilling, and record the hole depth, hole collapse and slurry leakage in detail. 7) When the measured data of the construction site is unknown, arrange a pilot hole every 20m to check the stratum change when the hole is finally formed. 8) The final hole depth of drilling should be 0.5 ~ 1.0m greater than the blowout depth, so as to meet the distance between a small amount of rock powder deposition and the front end of the nozzle. 9) After the hole is formed, remove the residual core and rock powder from the hole for replacement, and replace it with new mud to ensure the smooth operation of the high-pressure jet pipe. 10) After the hole depth reaches the design depth, measure the hole inclination. When the hole depth is less than 30m, the hole inclination is not more than 65438 0%. 1 1) Cover the orifice in time after drilling to prevent sundries from falling into the hole. 12) The drilling records shall be clearly and neatly filled in, signed by the supervisor, the quality inspector and the builder, and submitted to the technical team on the same day. 13) When casing and casing drilling methods are adopted, the holes should be filled with high-quality wall protection mud before pulling out the casing. 14) When vibroflotation immersed tube is adopted, the verticality between the frame and immersed tube (jet tube) shall be ensured to meet the design requirements. (4) Measuring hole depth: when drilling the final hole, measure the length of drill pipe and drilling tool; When the hole depth is more than 20m, the hole inclination is measured. (5) Lower the jet pipe: high-pressure jet grouting can be carried out only after the drilling experience is qualified. Check the following items before lowering the nozzle. 1) Measure the length of the injection pipe, and measure whether the center line of the nozzle is consistent with the direction arrow of the injection pipe, and the injection pipe should be marked with dimensions. 2) Place the nozzle near the high-pressure water pump, the pressure test pipeline should be less than 20m, and the pressure test injection should be adjusted to the design injection pressure. 3) During construction, try to spray the ground water, gas and slurry first, and then spray the pipeline, that is, the designed injection pressure+pipeline pressure. 4) Design the injection pressure+pipeline pressure as the standard injection pressure for construction, and readjust it when replacing the nozzle. 5) Before lowering the jet pipe in swing jet construction, field test should be conducted to adjust the jet direction and swing angle. 6) After passing the local interview, measures should be taken to prevent the nozzle from clogging when entering the injection tube. 7) When there is a lot of sediment in the hole, clay mud should be prepared in advance, and the injection tube should be lowered while rushing into the mud. 8) When drilling with casing wall protection, after lowering the injection pipe, pull out the casing wall protection. 9) When vibroflotation immersed tube is used, the above requirements must be met. 10) When grouting pipe goes down to the design depth and is approved by the supervision engineer, it is ready to start grouting. (6) Stirring pulping: The rotating speed and stirring capacity of the mixer should be adapted to the type of slurry being stirred and the displacement of grouting pump respectively, and the slurry should be uniformly and continuously stirred. Ensure the continuous supply of slurry for high-pressure jet grouting. 1) Mix cement slurry according to the designed water-cement ratio, and the common water-cement ratio is 1. 2) Cement slurry shall be stirred for at least 60s with a high-speed mixer; Use an ordinary mixer not less than 180s. 3) The mixing and storage time of pure cement slurry should be less than 2.5h 4) Cement slurry should be sieved before use, and its density should be tested regularly. 5) Pulping materials can be weighed by mass or volume, and the error should not be greater than 5%. 6) During construction in hot summer, heat and sun protection measures should be taken, and the slurry temperature should be kept at 5 ~ 40℃. 7) During construction in cold season, it is necessary to do a good job of cold protection and warmth preservation for the machine room and high-pressure jet grouting pipeline. 8) If hot water is used for pulping, the water temperature shall not exceed 40℃. 9) Before using the slurry, check the slurry conveying pipeline and pressure gauge to ensure that the slurry is smoothly sprayed into the stratum through the slurry conveying pipeline. 10) Cement slurry needs to be added with proper amount of additives and admixtures to form composite slurry, which should be determined by experiments. (7) Water supply and gas supply: the flow and pressure of high-pressure water and compressed gas for construction shall meet the engineering design requirements. 1) single pipe method, the density, flow and pressure of high-pressure cement slurry for construction shall meet the design requirements. 2) During the two-pipe construction, the flow and pressure of high-pressure cement slurry and compressed gas should meet the design requirements. 3) Three-pipe method, the flow and pressure of high-pressure water and compressed gas for construction shall meet the design requirements. (8) Jet grouting: The high-pressure jet grouting method is a continuous operation from bottom to top. Nozzle can be divided into single nozzle, double nozzle and multi-nozzle. 1) When grouting pipe goes down to the design depth and the nozzle reaches the design elevation, jet grouting can be started. 2) Blow in water, gas and mud that meet the design requirements, and start lifting after the mud returns to the orifice normally. 3) In the process of high-pressure jet grouting, if the pressure suddenly drops or rises, the reason must be found out and handled in time. 4) When the nozzle is dismantled during the spraying process, the falling overlapping spraying should be adopted, and the overlapping length should not be less than 0.2m. 5) When the spraying process is interrupted for some reason, the spraying should be resumed, and the overlapping length should not be less than 0.5m. 6) When the spraying interruption time exceeds the initial setting time of the slurry, the hole should be swept. When spraying is resumed, the overlapping length of re-spraying should not be less than1m. 7) In the process of injection, slurry leaks in the hole, and lifting is stopped until slurry does not leak, and lifting is continued. 8) In the process of grouting, if there is serious slurry leakage in the hole, grouting should be stopped, grouting pipe should be put forward, and sealing measures should be taken. 9) For grouting holes with special requirements, secondary grouting can be used to increase the grouting length and strength. 10) During the injection process, the whole construction time of each high-pressure injection grouting hole shall be recorded. (9) Slurry leakage: The amount of slurry leakage at the orifice of high-pressure jet grouting can reflect the grouting effect of the stratum cut by jet grouting. Whether the outlet slurry can be recycled depends on the engineering design and slurry quality, and recycled slurry should be used as much as possible in the project. 1) single-tube method and two-tube method, and the slurry from the orifice is not recycled. 2) Single tube method and double tube method. During grouting, it is normal that the amount of slurry leakage is less than 20% of the grouting amount. When the slurry leakage exceeds 20% or does not occur at all, the following measures should be taken: a. When there is a large gap in some layers, an appropriate amount of accelerator can be mixed into the slurry to shorten the consolidation time, so that the slurry can solidify in a certain soil layer, or the slurry leakage can be increased in the gap area. B when the slurry leakage is too large, the slurry leakage can be reduced by increasing the injection pressure or accelerating the injection lifting speed. 3) Three-tube method does not leak slurry when grouting, and the slurry leakage in the hole is serious. The following measures can be taken: a. When a small amount of slurry returns to the orifice, the lifting speed should be reduced, and when the orifice does not return to the slurry, the lifting should be stopped immediately. B. increase the concentration of cement slurry or cement mortar, and add a small amount of accelerator. C, reducing the grouting pressure and flow, and performing in-situ grouting. 4) Three-pipe method, according to the engineering design requirements, mud can be recovered from the orifice. A. Carry out high-pressure jet grouting in the stratum with less clay particles, and the slurry from the orifice can only be used after precipitation treatment. B grouting should not be recycled in cohesive soil or muddy soil layer from soft plastic to flowing plastic. (10) Rotary swing lifting: single nozzle swings 360 for rotary spraying; Less than 360 is arc spraying; Less than or equal to 180 is arch spraying; Less than or equal to 90 degrees for swing spraying; When the swing angle is 0, it is unidirectional fixed injection. The coaxial double-nozzle nozzle swings180 for rotary spraying; Less than 180 is bidirectional arch spraying; When the temperature is less than or equal to 90 degrees, it is a two-way swing spray; When the swing angle is 0, it is a two-way fixed spray. Non-coaxial double-nozzle nozzle has an included angle of 90,120 and150, which can be used for oscillating spray and fixed spray. Multi-nozzle nozzle has not been widely used in China at present. Pendulum is a mechanical pendulum and an artificial pendulum in special environment. 1) High-pressure jet grouting cuts a circle of soil, with slow swing and lifting speed, long jet radius and large pile diameter. 2) High-pressure swing jet cutting soil has slow swing and lifting speed, large jet radius and large curing volume. 3) High-pressure fixed jet cuts the soil, resulting in slow lifting speed, long jet radius and long solidified body length. 4) The lifting speed should be matched with the grouting quantity, which should meet the requirements of speed increase, and the speed increase should meet the length of injection radius. And 5) high-pressure rotary spraying machinery rotates to form a regular solidified body, and manual rotation forms an irregular solidified body. 6) In the process of rotating and swinging injection, the pile in the injection direction should be fixed, so as to check and prevent the displacement in the injection direction at any time. 7) Check the spraying direction when unloading and changing pipes during spraying to prevent the spraying direction from shifting. 8) Swing the jet according to the design requirements, lift it to the design elevation from bottom to top, stop the jet, and put forward the jet pipe. 9) Rotary jet grouting is suitable for fine-grained and coarse-grained loose formations, and fixed jet grouting is suitable for fine-grained loose formations. A. Fixed spraying: suitable for cohesive soil, silt and sandy soil with loose particles. B swing spraying: it is suitable for the stratum with loose particles in cohesive soil, silt, sand and gravel. C, jet grouting: suitable for cohesive soil, silt, sandy soil, gravel, pebble coarse-grained loose stratum. (1 1) Pile-forming and wall-forming: The solidified body by high-pressure jet grouting can be formed into the shape required by the design, for example, the rotary jet can be formed into a cylindrical shape and a disk shape, the oscillating jet can be formed into a fan shape, a bell shape, a trapezoid shape, a cone shape and a wall shape, and the fixed jet can be formed into a plate shape. (12) Filling and reinjection: After the completion of high-pressure jet grouting in each hole, the cement slurry in the hole will settle quickly, so it should be filled and grouted in time until it is full, and the slurry surface at the orifice will no longer sink. Filling and grouting after final injection is a very important work, and the quality of recharge will directly affect the quality of the project, so it is necessary to do a good job of filling and recharge. 1) Insert the slurry conveying pipe 2m below the slurry surface in the hole, and input the slurry for filling and grouting. 2) Filling grouting needs to be repeated many times, and the recharge standard is: until it is full, the slurry surface at the orifice will not sink again. 3) When high-pressure jet grouting solidified body has high strength requirements, it is forbidden to use grouting and slurry return for filling and reinjection. 4) When the high-pressure jet grouting solidified body only requires impermeability, grouting reinjection can be used for filling reinjection. 5) Recharge time, times, grouting quantity, cement dosage and recharge quality shall be recorded. (13) Completion of cleaning: After the completion of high-pressure jet grouting for each hole, the grouting pump and the slurry conveying pipeline should be cleaned in time to prevent the slurry from settling and caking in the slurry conveying pipeline due to untimely and incomplete cleaning, blocking the slurry conveying pipeline and nozzle and affecting the construction of the next hole. 6.9.4 Quality standard 1. Measuring and setting out of process index (1): According to the design and construction drawing, the allowable deviation is 10mm, and when the length is more than 60m, the allowable deviation is15mm ... (2) Determine the hole position: the allowable deviation of the ground elevation of the measuring orifice shall not exceed 65438±0cm, and the allowable deviation of the hole position shall not exceed 2cm. (3) Drilling with drilling rig: When the drilling rig is in place, the allowable deviation of the central axis of the main drill pipe is less than 5cm. 1) drilling diameter: the opening diameter shall not be larger than the outer diameter of the injection pipe 10cm, and the final drilling diameter shall be larger than the outer diameter of the injection pipe by 2cm. 2) Wall protection: mud is used to protect the wall, and the density of clay mud is1.1~1.25g/cm3. 3) Drill pilot holes: arrange a pilot hole every 20m, and core at 1m to determine the lithology at the bottom of the hole. 4) Drilling depth: the final hole depth is 0.5 ~ 1.0m greater than the designed blowout depth. 5) Borehole inclinometer: When the hole depth is less than 30m, the hole inclination should not be greater than 1%, and the rest should not be greater than 1.5%. (4) Measuring hole depth: Measure the length of drill pipe and drilling tool when drilling the final hole, and the allowable deviation shall not exceed 5cm. (5) Lower the injection pipe: the allowable deviation from the injection pipe to the designed opening depth shall not exceed 10cm. 1) nozzle: the allowable error is less than 2% when measuring the total length of the nozzle, and the nozzle size is marked every 0.5m 2) directional arrow: the allowable error between the centerline of the measuring nozzle and the directional arrow of the nozzle is less than 1. 3) Debugging nozzle: When determining the design injection pressure, the pressure test pipeline should not exceed 20m, and it should be debugged again when replacing the nozzle. 4) Injection pressure: the standard injection pressure for construction is equal to the design injection pressure plus the pipeline pressure. 5) Injection direction: ensure that the allowable deviation of injection direction does not exceed 1. (6) stirring and pulping: stirring with a high-speed stirrer for at least 60 seconds; ; Use an ordinary mixer not less than 180s. 1) Single pipe method and double pipe method, the common water cement ratio is 1, and the density is 1.35 ~ 1.5g/cm3. 2) Three-tube method, the common water-cement ratio is 0.6 ~ 0.8, and the density is 1.6 ~ 1.7g/cm3. 3) The weighing error of pulping materials is not more than 5%, and the weighing density deviation is not more than 0. 1g/cm3. 4) The mixing and storage time of pure cement slurry shall not exceed 2.5h, and the slurry temperature shall be kept at 5 ~ 40℃. 5) The cement entering the site shall be sampled and tested every 400 tons 1 time, and the stability and strength indexes of the cement shall be tested. 6) Cement shall be used in turn according to the factory date and batch number. Unqualified cement is strictly prohibited. (7) Water supply and gas supply: the pressure of high-pressure (slurry) water is not less than 20MPa, and the gas pressure is controlled at 0.5 ~ 0.8 MPa. 1) high-pressure slurry: the pressure deviation of high-pressure slurry for construction shall not exceed 1MPa, and the flow deviation shall not exceed 1l/min. 2) High-pressure water: the pressure deviation of high-pressure water for construction shall not exceed 1MPa, and the flow deviation shall not exceed 1l/min. 3) compressed gas: the pressure deviation of compressed gas for construction shall not exceed 0. 1MPa, and the flow deviation shall not exceed 1l/min. (8) Jet grouting: After high-pressure jet grouting starts, the cement slurry will return to the orifice and start lifting. If the pressure suddenly drops or rises during the injection, the reason must be found out and handled in time. During the spraying process, mud leaks into the hole and the lifting stops. 1) Check nozzles: unqualified nozzles, nozzles and gas nozzles are prohibited from being used. 2) Overlap of re-spraying: If it is interrupted for 0.5h, 1h and 4h, it will overlap by 0.2m, 0.5m and 1.0m respectively. 3) The normal working pressure of three-pipe grouting is 0. 1 ~ 0.3 MPa. 4) In order to increase the length and intensity of injection, the nozzle of the injection pipe must be lowered to the original position of injection. (9) Grouting: Three-tube method, in which high-pressure jet grouting is used for sand and gravel layer, and the slurry from the orifice can be used after filtration and precipitation, and the density of recycled slurry is 1.2 ~ 1.3g/cm3. (10) Swing lifting: When the gravel soil is a skeleton structure, the construction technology of high-pressure jet grouting should be carefully adopted. 1) rotary spray: the allowable deviation of the number of rotary swings (rotary spray speed r/min) shall not exceed 0.5r/min of the design value. 2) Swing spray: The allowable deviation of swing times (swing spray speed times/minute) should not exceed 1 time/minute of the design value. 3) Lifting: the lifting speed of rotating, swinging and fixed spraying, and the allowable deviation shall not exceed 65438 0 cm/min of the design value. (1 1) Pile formation and wall formation: rotary jet grouting, swing jet grouting and fixed jet grouting, and the geometric dimensions shall meet the design requirements. (12) Filling and reinjection: After the last grouting is put forward from grouting pipe, the hole shall be filled and grouted in time until it is full. 1) Insert the slurry conveying pipe 2m below the slurry surface in the hole, and input the slurry for filling and grouting. 2) Filling grouting needs to be repeated many times, and the recharge standard is: until it is full, the slurry surface at the orifice will not sink again. (13) End of cleaning: After grouting is completed in each hole, grouting pump and slurry conveying pipeline shall be thoroughly washed with clean water. 2. Finished product quality (1) The technical indexes of piles, walls and slabs formed by high-pressure jet grouting should meet the design requirements: 1) The diameter of jet grouting pile should be greater than or equal to the design pile diameter, and its strength and impermeability indexes should meet the design requirements. 2) The average thickness of the swing shotcrete wall should be greater than or equal to the design wall thickness, and its strength and impermeability index should meet the design requirements. 3) The minimum thickness of nozzle plate should be greater than or equal to the design thickness, and its strength and impermeability index should meet the design requirements. (2) In the foundation reinforcement project, the bearing capacity of the foundation after high-pressure jet grouting treatment must meet the design requirements. 3. The quality of high-pressure jet grouting foundation shall comply with the provisions of Table 6.9.4.3. Table 6.9.4.3 High-pressure Jet Grouting Foundation Quality Inspection Standard Item Sequence Inspection Item Allowable Deviation Allowable Value Inspection Method

unit value

The main control items 1 cement and additives meet the factory requirements. Check the product certificate or sample for inspection.

2 cement dosage design requirements check the cement slurry flow table and water cement ratio.

3 according to the provisions, check the design requirements of pile strength or integrity.

4 The design requirements of foundation bearing capacity shall conform to the prescribed methods.

General project 1 drilling depth mm ≤ 50 steel rule quantity

2 Borehole verticality% ≤ 1.5 theodolite to measure drill pipe or actual measurement.

3 hole depth plus or minus ±200mm measured with steel rule.

4 Check the grouting pressure of the pressure gauge according to the specified parameters.

5 steel straightedge measurement of pile body mm > 200

⑥ Dig with steel ruler after the pile diameter is mm≤50.

7 allowable deviation of pile center

After excavation ≤ 0.2D, measure 500mm below the pile top with a steel ruler, where d is the pile diameter.

6.9.5 Construction test plan 1. Parameter Determination (1) Before construction, select the sections with similar engineering conditions in the site, conduct field tests, and determine the construction process parameters. (2) To prepare for the overall construction of the project, first select a few parts of the project for trial construction and determine the construction process parameters. (3) When there are problems with the technical parameters used in the construction, the construction process parameters should be corrected and adjusted in time. 2. Construction test (1) According to the pre-construction test required by the project, categories such as rotary spray, swing spray and fixed spray can be selected. (2) The jet grouting pile, swinging jet wall, single jet belt fixed jet plate, connection or surrounding well test can be selected as the jet form and structure. 6.9.6 Safe and civilized construction 1. Work safety (1) Seriously study the Law of People's Republic of China (PRC) on Work Safety. Abide by the national laws and regulations on safety production, strengthen the management of safety production, and conscientiously implement the policy of "safety first, prevention first". Establish a safe production system to ensure safe production. (2) Based on the national laws, regulations, rules and decisions on production safety, and in accordance with the objectives and requirements of the competent department of production safety management, the principle of compartmentalization and hierarchical management is implemented, and construction safety is put in the first place to ensure construction production safety. (3) Strengthen the publicity and education of safety production, improve the awareness of safety production, and focus on the following aspects of safety education: 1) Violation safety education. 2) Owner's sense of responsibility and safety first education. 3) Education on basic knowledge and skills of production safety. 4) Abide by rules and regulations and post standardization education. (4) Establish and improve the safety production guarantee system, implement the responsibility system for safety posts, define the division of labor, and assign responsibilities to people. (5) In order to ensure the safe and smooth progress of the project, the construction site should be equipped with enough safety personnel, equipment and tools. (6) Hang construction safety slogans at the construction site, and set up safety signs and safety protection measures. 1) All power supply systems on the construction site are equipped with leakage protection devices, and there is enough lighting for construction at night. 2) The construction work area, office area and living area should be equipped with sufficient lighting facilities to meet the needs. 3) Set up standby power supply in the construction work area, office area and living area. 4) Installation of lightning rods for electrical appliances, temporary buildings and construction equipment that are vulnerable to lightning strikes. (7) Establish safety production organization, formulate protective measures and formulate corresponding safety production operation procedures. 1) Strengthen the education of workers' safety in production, and organize workers to seriously study and implement safety operation procedures. 2) Construction personnel must wear safety helmets when entering the site, and aerial work personnel must fasten their safety belts. 3) Non-electromechanical personnel are forbidden to use electromechanical equipment, and non-electricians are not allowed to repair electrical equipment. 4) Water vapor pumping station, mixing station and distribution box must be equipped with canopy or rain cover according to regulations. 5) Strengthen the control and treatment of dust, noise, waste water and waste gas in the construction site. 6) Adhere to the "three firsts" principle of material transportation and site occupation, and establish a good corporate image. 7) Strengthen the ideological and disciplinary education of employees, and put an end to public security incidents such as fighting.