The sinking speed can be controlled by the current monitoring meter of the motor, and the working current shall not be greater than the rated current.
If the error (%) of slurry consumption of single pile is less than 1, check the construction records.
The number of core drilling shall not be less than 2% of the total number of piles and shall not be less than 5.
2.
The weight ratio method is used to control the mixing of cement slurry, and computer batching is used.
Repeated mixing: the number of repeated mixing shall meet the design requirements.
5.
4.
After passing the quality inspection, the supervising engineer shall fill in the field quality inspection report form of wet jet grouting pile.
When the cement mixing pile machinery is in place, the deviation and verticality of the machinery shall meet the design and specification requirements.
Before excavation, the pile quality shall be tested by core drilling method, and the number of cores shall meet the design and specification requirements.
Observe with theodolite or plumb hammer to ensure the verticality of the drilling rig.
3.
Unconfined compressive strength (MPA) of pile body shall not be less than 2 ‰ of design value..
If it does not meet the design requirements, the construction process shall be adjusted in time.
4.
5.
When the mixer is lifted to the design top elevation, the cement slurry in the collecting hopper shall be just emptied.
The verticality accuracy of mixing pile shall not be less than 1 / 200.
4.
The uniaxial compressive strength of cement mixing pile at the age of 28d shall not be less than 1.0MPa, and five groups of tests shall be conducted, with no less than three pieces in each group.
The uniaxial compressive strength of cement mixing pile at the age of 28 days shall meet the requirements of design and specifications.
2.
2) When mixing, add water first, then add cement according to the mix proportion of the laboratory and put it into the mixer (see Figure 2 below).
3.
2.
Cleaning: inject an appropriate amount of hot water into the collecting hopper, start the mortar pump, clean the residual cement slurry in all pipelines until it is basically clean, and clean the sundries adhered to the mixing head.
5.
Before moving, see the situation of the front, rear, left and right positions.
If there is any deviation, it shall be corrected in time, and the pile position deviation shall not be greater than 50mm.
The surveyors shall carry out the survey and setting out work related to the mixing pile position, original ground elevation and orifice elevation according to the design and construction drawings, and make the survey and setting out records and pile layout drawings.
The pile driver shall be in place stably and straightly.
The pumping pressure of cement mixing pile shall meet the design requirements, and the pumping flow shall be constant.
After moving, check the positioning situation.
3、 Trench excavation 1.
The pumping pressure of cement mixing pile is 0.3MPa, and the pumping flow shall be constant.
Before construction, they shall report to Party A and the supervising engineer for review, fill in the survey and setting out inspection form, which shall be reviewed and signed by Party A and the supervising engineer.
For cement mixing pile, excavation inspection shall be carried out within one week after construction or pile quality shall be checked by means of drilling and coring.
When the specific gravity of cement slurry is lower than the design specific gravity, the cement slurry of this batch shall be discarded.
Construction flow chart of cement mixing pile I.
3.
3.
When the mixing head sinks to the design depth, the verticality of the machine shall be checked and adjusted again.
2.
The steel plate and road base plate shall be laid under the pile driver.
6.
Preparing cement slurry and slurry 1) for each batch of cement mobilized at the construction site, the supervisor, Party A and the construction unit shall jointly weigh the cement tank truck to ensure the dual control of the weight of cement mobilized.
When the cement mixing pile machinery is in place, the maximum deviation shall not be greater than 2cm, and the verticality of the leveling machinery shall not be greater than 1% of the pile length.
6.
Set pile position marks every 5m on the pile positioning control line to ensure that the overlapping between piles meets the specifications and design regulations.
The pile length (mm) shall not be less than the design, and the construction records shall be checked.
Lifting shotcrete mixing: after the mixer sinks to the design depth, start the mortar pump, press the cement slurry into the foundation, spray and rotate, and lift the mixer in strict accordance with the lifting speed determined in the design.
2.
3.
5.
Generally, the slurry is mixed on site.
The cement used for cement mixing pile, cement content in active area, cement content in passive area, water cement ratio of cement slurry and admixture shall meet the design and specification requirements.
In the process of trench excavation, the construction unit is required to have a special person responsible for on-site guidance.
Case: design requirements for cement mixing pile of Wenzhou Guoxi project 1.
In order to mix the soil and cement slurry evenly, it is generally necessary to mix for many times.
There is a digital display screen in the control room to display the weight of water and cement added each time (see Figure 1 below).
II Before setting out of pile position, the traverse points and benchmarks handed over by the planning and surveying unit shall be rechecked and used after confirmation.
6) The Mud Hydrometer shall be placed on the construction site for easy inspection at any time.
Before the operation of pile machine, the on-site supervisor and Party A shall check whether the mixing pile machine reaches the operation position.
The drilling and lifting speed of the drilling rig shall meet the design requirements.
5.
According to the construction plan of cement soil mixing pile, the positioning control line of pile shall be set at the edge of the trench.
Pre mixing sinking: after the cooling water circulation of the mixer is normal, start the mixer motor, loosen the crane steel wire rope, and make the mixer mix and cut soil along the guide frame to sink.
Depth deviation (mm) ≤ 50, spot check 2%.
The construction of cement mixing pile shall adopt the mixing process of three times up and down of the mixing head.
In order to prevent the uplift of cement soil during the construction of cement mixing pile from affecting the construction, the construction groove shall be excavated according to the contour line of cement soil mixing pile on site, and the depth of the groove shall be determined according to the amplitude and length of the pile.
The foundation pit excavation can only be carried out when the strength of cement mixing piles reaches the age of at least 28 days.
4.
When the mixing head sinks to the design depth, the verticality of the machine shall be checked and adjusted again.
According to the construction drawing, the construction contour of cement mixing pile shall be measured on site as the boundary of trench excavation.
7.
The cement mixing pile adopts 42.5 ordinary portland cement, the cement content in the active area is 15%, the cement content in the passive area is 15%, the cement slurry water cement ratio is 0.45, and 0.05% triethanolamine and 0.2% lignin are added; 2.
According to the construction experience in Wenzhou, the lifting (or sinking) speed during spraying is 0.8 ~ 1.0m/min.
Before excavation, the pile quality shall be tested by core drilling method.
Inclination (%) ≤ 1.5, check the construction records.
5、 Requirements for design parameters of cement mixing 1.
Test preparation: raw materials shall be sampled and submitted for inspection as required, and put into use after passing the retest.
When the drill pipe is lifted, check whether all the cement slurry is injected.
Pile position deviation (mm) ≤ 50, spot check 2%.
9.
Scheme preparation: prepare relevant construction schemes and submit them to the owner and the supervisor for approval before implementation.
The foundation pit excavation can only be carried out when the strength of cement mixing pile reaches the age of at least 28 days.
The inspection items, quality standards, inspection methods and frequency shall meet the specification requirements.
3.
5.
Disclosure preparation: hold a meeting of all personnel of the project department to make construction technology and safety technology disclosure to the construction personnel and operators, so that the employees can understand the design intention, master the construction essentials, key processes and safety operation procedures, and achieve clear division of labor and clear responsibilities.
Before construction, the ponding in the trench must be removed to prevent the ponding from infiltrating and affecting the pile strength of cement soil mixing pile.
8.
4.
Displacement: repeat the above steps 1-4 before the construction of the next pile.
The construction mixing times, lifting (or sinking) speed during spraying and pumping pressure of cement mixing pile shall meet the design and specification requirements.
3) Put it into the cement slurry storage tank after full mixing (see Figure 3 below); 4) The cement used for cement mixing pile, the cement content in the active area, the cement content in the passive area, the water cement ratio of cement slurry and additives shall meet the design and specification requirements.
construction preparation 1.
5) The supervisor and Party A shall supervise the whole process during the backstage construction.
4、 The construction worker and the pile driver shall command the pile driver to be in place.
If any obstacle is found, it shall be removed in time.
4.
6、 Mixing into piles 1.
7.
Site preparation, survey preparation, pile test, etc.
7、 Construction quality requirements for cement mixing pile 1.
The pile diameter (mm) shall not be less than the design, and 2% shall be spot checked.
Construction drawing preparation: be familiar with and master the design and construction drawings, fully understand the design intention, and communicate with the design unit in time if there is any doubt.
