Temporarily arrange two sets of equipment to complete the pile test within the time specified by the owner (equipment can be added if appropriate).
(8) After the main coordinate control points are measured, the plane control network of the whole construction site shall be established.
Lay out the survey control system, establish the survey control network according to the control and benchmark provided by the owner, and set coordinates and elevation control points outside the influence range of pile driving on the construction site, which can be put into use only after being checked and confirmed by relevant units such as planning, design and supervision.
Characteristic value of foundation bearing capacity FAK = 400kPa; (4) Moderately weathered marl: 5-10m thick, greenish gray, grayish black, moderately weathered.
Argillaceous structure, layered structure.
Characteristic value of foundation bearing capacity FAK = 2000kN.
The geological conditions below the original ground of the case project are as follows: (1) plain fill: the layer thickness is 0.60-14.5m, yellowish brown, grayish brown, loose and slightly wet.
The lifting point shall be set at 0.29l (L is the pile length) (as shown in the figure below).
It can be used only after passing the acceptance.
▲ schematic diagram of two-point lifting ▲ schematic diagram of one-point lifting is the same for the pile lifting operation by the winch provided by the pile machine.
The rock mass is relatively complete and hard, and the core is columnar and short columnar.
In order to prevent the self weight of the pile driver from squeezing the soil when the pile driver is in place and causing the displacement of the measured pile position, the correctness shall be rechecked after the pile driver is in place and before formal pile pressing, and the pile positioning deviation shall be controlled within 20mm.
Characteristic value of foundation bearing capacity FAK = 200kp; (3) Strongly weathered marl: 0.6-19.9m thick, grayish brown, grayish black and strongly weathered.
(2) Eluvial silty clay: 1.2-27m thick, yellowish brown, grayish black, plastic, medium dry strength, medium toughness, no shaking response, slightly shiny.
It is mainly clayey soil, containing a small amount of block stones, plant roots, etc., which is newly artificially filled.
All pile foundations and hybrid foundations are proposed to use prestressed pipe piles with a diameter of φ 400、 φ 500 prefabricated pipe piles, and the models of prefabricated pipe piles are phc-400a95 and phc-500a100 prestressed pipe piles respectively.
The pipe pile joints under the same bearing platform shall be staggered from each other.
(1) It is preferred to learn the general layout, engineering characteristics and design intention of the project through the study of the general layout and design drawings of the case project.
And understand the location and coordinates of red line points in the project area, surrounding environment, site terrain, etc.
The process procedure is as follows: (a) prepare to press the first section of pile; (b) Connect the second section of pile; (c) Connect the third section of pile; (d) Flatten the whole pile to the ground; (e) 1 – the first section of pile is completed by sending and connecting pressure pile; 2 – second section pile; 3 – third section pile; 4 – pile delivery; 5 – pile joint; 6 – ground line; 7 – operation platform line of pile pressing frame 4.2.
4、 Construction process and method 4.1 selection of construction process through the analysis of the engineering design drawings and the geological data provided, the careful understanding of the engineering design drawings, and the comprehensive evaluation of the performance of the existing equipment, the static pressure construction process is adopted for the case project, The construction process is as follows: Surveying and setting out → pile driver in place → rechecking the pile position → hanging the pile steel wire rope → lifting the pile → two-way correction of pile tip into the soil and stabilizing the pile → preliminary pressurization → checking the verticality of the pile body → formal pile pressing → observing and correcting the verticality of the pile body → when pressing to 1m from the pile top to the ground, Then lift the pile in place → weld the pile → continue to press the pile → record the pressure value → pile forming → move the next pile to press the pile.
(5) According to the coordinates provided on the general drawing, the distance and angle required for measurement are calculated, and the plane control network is measured after being converted into polar coordinates through coordinate inverse calculation.
The construction can be carried out only after the pile position is measured and set out and reviewed by the supervision unit.
(2) The quality inspection personnel shall jointly inspect and accept the prestressed pipe pile with the on-site supervisor.
Calcareous argillaceous structure, layered structure, and the basic quality grade is grade III.
See the drawings of each building for the elevation.
Pile driving is 18# required for the case project.
If any nonconformity is found during acceptance, it shall be marked and returned in time.
The location of the test pile shall be based on the coordinate points provided by the owner.
See the drawings of each building for the elevation of the top of the test pile, see the drawings of each building and the geological report for the pile length.
4.2.2 acceptance of precast piles (1) when precast piles leave the factory and arrive at the construction site, the factory certificate of precast piles shall be checked and received in batches.
4.2.4 for vertical pile and inserted pile, the pile position shall be rechecked by rectangular coordinate method according to the set control points, and the first section of pile shall be lowered after it is correct, and the deviation between the center point of the pile tip of the first section of pile and the pile position shall be controlled within 20mm..
During the lifting and transfer of piles, the operators shall follow the safety operation procedures for lifting.
Measure and set out the pile position, set the building axis and corner pile according to the control point, measure and set out the pile position according to the pile position layout, and mark the center of the pile position with reinforcement or bamboo stick.
The pile end entering the bearing layer is greater than or equal to the pile length and penetration control.
(7) After each measurement with rectangular coordinates, it shall be checked.
Click the blue font above to subscribe for free! 1、 Case project overview the case project adopts three types of foundations, namely pile foundation, mixed Foundation (pile foundation combined with excavation foundation) and natural shallow foundation.
During pile test, measures shall be taken to ensure the lateral stability of pile body.
(9) The building axis and main control points are measured and set out to prepare for pile foundation setting out.
It is mechanically pushed and filled.
2、 Purpose of pile test after the completion of pile test, determine the design, construction and other parameters of pile foundation engineering through the static load test of pile, select the bearing layer of pile foundation, determine the possibility of pile sinking, select the static pressure value, and determine the pressure stop standard during pile driving construction.
The elevation of ± 0.000m is equivalent to the absolute elevation of 105m-107m.
(3) After retesting the elevation and coordinates of the benchmark provided by the bidding unit, the visa handover procedures shall be handled in time.
3、 Pile test selection, pile test sequence and progress.
Weathering cracks are developed, and the rock core is massive.
Dry drilling is not easy to drill.
The main coordinate control points shall be protected as necessary.
Construction methods of main projects 4.2.1 surveying and setting out and pile positioning 1.
The bearing capacity of single pile is finally determined according to the on-site static load test.
2.
The engineering pile can be constructed only after the bearing capacity of the engineering test pile meets the design requirements.
The rock mass is broken and soft.
(2) Be familiar with and understand the layout, positioning basis, positioning conditions and main axes of ground buildings.
According to the relevant drawings and relevant national specifications provided by the owner, the number of test piles for the case project is 54.
According to the actual situation, if the earthwork is not in place and some drawings are incomplete, at the request of the owner, test 18#, 15#, 14#, 13#, 12#, and then test the pile from south to north.
(6) During surveying and setting out, the measured coordinate points on the construction site shall be checked first, and then the coordinate points on the layout plan shall be measured according to the measured coordinate points, and each coordinate point shall be distributed in the construction site.
This layer is a weathered residual layer of marl.
The estimated characteristic values of vertical bearing capacity of single pile shall not be greater than 570kn and 820kn respectively.
The pile bottom elevation difference of adjacent piles shall not exceed 1 / 10 of the length of adjacent piles and the adjacent center distance.
(4) On the basis of knowing and mastering all pile foundation design drawings, check whether the positioning coordinates and dimensions marked on the general drawing are accurate by calculating the closed traverse method.
(10) The surveying accuracy shall be ensured during the surveying and setting of horizontal control network, and the closed adjustment shall be carried out after the surveying and setting of control network.
4.2.3 the method of two lifting points shall be adopted for pile lifting and in place pile on-site lightering, and one lifting point shall be adopted for pile feeding.
During the lifting process, the lower part of the pile shall be stabilized with supporting rope, the crane shall minimize the elevation angle of the boom (and the length of the boom as far as possible), slowly drag the pile close to the pile crane, and then start vertical hook lifting, Feed the pile smoothly into the pile machine holder.
The basic quality of rock mass is registered as grade v.
