Construction scheme of airport surcharge preloading

Special scheme for subgrade surcharge preloading construction

catalogue

I. Compilation Basis 1

II. Project Overview 1

Three. Design requirements for surcharge preloading 1

Fourth, the purpose of surcharge preloading 2

Verb (abbreviation for verb) resource allocation 2

5. 1 Staffing 2

5.2 Mechanical Configuration 2

5.3 Material Preparation 3

VI. Duration 3

Seven, the construction of surcharge preloading 3

7. 1 Construction of Pollution Prevention Layer 3

7.2 Construction of surcharge preloading soil 5

Eight. Settlement observation of surcharge preloading 6

8. 1 Embedding of settlement observation pile 6

8.2 Settlement observation 6

8.3 Analysis and Evaluation of Settlement Data 6

8.4 Dynamic Control Report of Settlement Observation 7

Nine. Unloading and settling filling 7

9. 1 uninstall 7

9.2 Settlement Filling 7

X. Safety assurance measures 8

XI。 Environmental protection measures

Twelve. Quality control measures for overload preloading 9

I. Basis for compilation

1, general subgrade drawing (construction drawing of Xinlan New Second Double Line);

2. New Lanxin second double-line process control standardization manual;

3. Interim Standard for Acceptance of Construction Quality of Railway Subgrade Works for Passenger Dedicated Lines (Tie Jian [2005] 160).

4. Relevant documents of Gan Qing Company;

5, subgrade worksite design, related bridge and culvert worksite design.

Second, the project overview

1, scope and quantity of preloading subgrade:

According to the design requirements, the subgrade of Bid Section 4 of the pipeline section of this shelf team needs to be pre-pressed. According to the latest design requirements, all transition sections (roads and bridges, culverts, embankments and cuttings, roads and tunnels) also need to be preloaded, and there are 23 transition sections in this section that need to be preloaded. The total length of subgrade surcharge preloading is 2356.74m, the subgrade section of surcharge preloading section is embankment and shallow cutting, and the foundation treatment measures are impact rolling.

Length of mileage section of preloading subgrade m Remarks on amount of preloading soil m3 in subgrade table

Dk706+700.00 ~ Dk707+546.1846.1low embankment 296 13

Dk707+613.9 ~ Dk710+199.17 2585.27 The design of high embankment is undecided.

Dk710+858.31+dk71+247.71389.40 high embankment 13629.

Dk712+367.42 ~ Dk713+009.81.642.39 High embankment +072 17.

Dk713+171.15 ~ dk713+650.00 478.85 low embankment 16760.

2. Overview of overload preloading

After subgrade treatment, embankment filling should be carried out. When filling the bottom of subgrade bed (with 5cm interlayer), according to the design requirements, preloading, deformation observation and subgrade settlement analysis and evaluation are carried out. After the subgrade settlement is stable, unload the precompressed soil, and carry out the construction of subgrade bed surface graded macadam.

Third, the design requirements of surcharge preloading

After the construction of the bottom layer of embankment foundation bed is completed, surcharge preloading measures should be taken to accelerate the settlement. In general sections, the earthwork for surcharge preloading adopts trapezoidal section, with a top width of 8m, a height of 3m and a slope of 1: 1. Before preloading, a layer of composite geotextile (> 150 g/m2, CRB bursting strength not less than 2.0KN) should be laid on the top surface of the bottom of subgrade bed. During construction, geotextile should be prevented from being damaged, so as to prevent surface precipitation from infiltrating into the bottom of foundation bed. After preloading is completed, its surface is covered with geotextile to prevent soil erosion. The surcharge preloading soil should be properly compacted to ensure the stability of the surcharge preloading soil. The unit weight of precompressed soil shall not be less than 18KN/m3. During surcharge preloading, settlement observation should be strengthened, "settlement-time" curve should be drawn, and settlement prediction and post-construction settlement budget should be made well. Unloading can only be carried out when the calculated post-construction settlement meets the requirements.

The precompression length of the transition section is required to be 5m longer than that of the transition section.

Fourth, the purpose of surcharge preloading

Train and track loads account for a considerable proportion in post-construction settlement calculation. Without surcharge preloading, the subgrade is under-loaded, and after adding the upper track structure and train load, the subgrade will inevitably settle. Because the ballastless track has strict requirements on the post-construction settlement of subgrade, the reliability of theoretical calculation is not high. In order to effectively control the post-construction settlement and accurately determine the track laying time, it is necessary to carry out preloading and settlement observation on the ballastless track subgrade.

Verb (abbreviation for verb) resource allocation

The resources of the surcharge preloading construction plan in this work area are as follows:

5. 1 staffing

Set up two subgrade stacking construction teams, including two team leaders, two technical directors, two construction site technicians and 1 settlement observation team, to be responsible for the construction of subgrade stacking engineering. In addition to all kinds of mechanical operators, the operators are also equipped with 10 skilled workers who are familiar with geotextile laying and 20 other ordinary workers, who are responsible for preventing the laying and removal of contaminated layers, trimming the stacking surface and removing the parts that need manual operation during preloading.

5.2 mechanical configuration

List of construction machinery and equipment for surcharge preloading soil

Serial number mechanical name specification unit quantity

1 excavator PC400 sets 4

Two ZL50 loaders and two loaders.

3 bulldozer t 140 2 sets

PY 180 motor grader 4 sets 2

5 Roller 25t Platform 2

6 20 m3 dump trucks 15

7 Measuring Instrument Sleeve 2

5.3 Material preparation

Two-cloth and one-cloth composite geotextile for surcharge preloading has been put in place and passed the test, with a consumption of 73982m2. Heap preloading soil is excavated and abandoned on both sides of subgrade, and soil is taken temporarily, with the dosage of 772 19 m3.

Six, time limit for a project arrangement

According to the completion time of subgrade filling and the end time of beam transportation, the construction period is arranged as follows:

Number unit project name planning time limit for a project

1dk 706+700.00-dk 707+546. 1 20 10. 12. 10-20 10. 12.20

2dk 7 10+858.3 1-dk 7 1 1+247.7 1 20 10. 1. 1. 15-20 10. 1.20

3dk 7 12+367.42-dk 7 13+009.8 1 20 10. 1. 15-20 10. 1 1.20

4dk 7 13+ 17 1. 15-dk 7 13+650.00 20 10. 1. 15-20 10. 1.20

Seven, the construction of surcharge preloading

7. 1 construction of pollution prevention layer

7. 1. 1 top surface treatment of foundation bed bottom

After inspection, the elevation, width, transverse slope and smoothness of the embankment shall be measured when the bottom layer of the subgrade is filled to the top layer, and the sub-project table of the bottom layer of the subgrade shall be filled after completion. After the self-inspection is qualified, it shall be reported to the supervision engineer for inspection and acceptance, and the surcharge preloading construction shall be carried out after the acceptance is qualified.

Clean up the top surface of the bottom layer of qualified foundation bed, and sweep away the hard objects protruding from the surface to make the surface of foundation bed smooth, smooth and free of potholes. Local potholes or irregularities should be corrected manually to make it smooth.

7. 1.2 Laying impervious geotextile

Before preloading filling construction, a layer of geotextile with two cloths and one cloth shall be laid on the top surface of subgrade to prevent preloading soil from polluting the bottom of subgrade and preventing surface precipitation from infiltrating into the bottom of subgrade. At the same time, it also provides a demarcation basis for unloading after the expiration of preloading, preventing the disturbance of subgrade bottom structure during unloading and ensuring the integrity and stability of subgrade. Geotextiles for surcharge preloading shall be tested and meet the design requirements (> 150g/m2, CRB bursting strength not less than 2.0KN).

Geotextiles are laid immediately after the top surface of subgrade bottom layer is treated, generally from one side of subgrade to the other side along the cross-sectional direction of subgrade. The longitudinal and transverse joints of geotextile shall be overlapped, and the overlapping length shall not be less than 10cm. The overlapping direction should be consistent, and the side in the direction of preloading soil should be placed on it. Geotextiles should be laid flat and straight, without wrinkles, distortion, damage, etc. At the same time, we should pay attention to reducing joints as much as possible to avoid excessive stretching and damaging the performance of geotextile. When the slopes overlap, geotextiles should be properly stitched manually. Both sides of the top surface of precompressed soil are covered with 2m, and the soil is pressed to prevent it from being blown by the wind.

10cm10cm10cm

Composite geotextile

Loading and expansion direction of preloading soil

Relationship between overlapping and laminating methods of geotextiles and preloading soil load

7.2 Construction of surcharge preloading soil

The sequence of preloading construction technology is: laying geotextile → filling preloading soil in layers → placing settlement plate and observing → unloading after passing the test.

For the construction process, see "Block Diagram of Heap Preloading Construction Process".

According to the design requirements, after the subgrade is filled to the bottom of the subgrade bed, the preloading soil boundary line is measured and the preloading soil construction is started. Pre-pressed soil shall be excavated at the designated borrow yard near the excavation section, and silt soil or fillers containing garbage and sundries shall not be used. The piled soil is filled into a trapezoidal section, with a trapezoidal top width of 8m, a trapezoidal bottom width of 14m, a height of 3m and a slope of1:1; The transition section adopts sand bag preloading, and the preloading section is the same as that of the adjacent subgrade; The gradient of the longitudinal slope at the end of the construction site is 1: 2, and the bridgehead extends to the bridge with the gradient of 1: 2. The top surface of surcharge preloading soil should be made into a 2% cross slope, and corresponding drainage measures should be taken.

When filling, soil shall be loaded by excavator or loader, transported by dump truck, spread by bulldozer, leveled by grader with people, and compacted by loader' tires or excavator tracks'. The layer thickness of layered filling shall not be greater than 1m, and the average bulk density of the compacted fill shall not be less than 18kn/m3. The density of each layer is detected by irrigation method, and the actual bulk density of the pile soil is calculated as follows:

Soil bulk density r = soil density ρ× gravity acceleration g.

Namely: r =ρ×g The unit of bulk density is kN/m3, and the unit of density is kg/m3.

G = 9.8m/s 2

Therefore, the compaction density of preloading soil is not less than ρ =18kn/m3/9.8m/S2 =1.84g/cm3.

After each layer of pile soil is compacted, the compactness of this layer is measured by irrigation method. When the density is not less than 1.84g/cm3, the next layer shall be filled after the test is qualified, meets the design requirements and is approved by the supervisor.

When stacking, the loading speed should be strictly controlled, and the soil should be kept flat. In the process of filling preloading soil, the observation frequency of subgrade settlement observation plate and lateral displacement observation pile should meet the requirements of the code to ensure the stability of subgrade under various loads. When the rate of land subsidence of the center line of the embankment is greater than 10mm/ day and night, and the horizontal displacement rate of the slope toe is greater than 5mm day and night, the filling shall be stopped immediately, and the filling shall be carried out after the observed value is restored to the limit value. After filling, the surface should be smooth, and the cross slope should not be less than 2%, so as to prevent water accumulation on the surface and scour the subgrade. When the preloading earthwork reaches the designed filling height, it begins to enter the static preloading period.

Before preloading soil is filled, surveyors will put the settlement plate in place according to the design requirements. During the filling process, 1m× 1m× 1m steel bar protection frame will be used to protect the settlement observation equipment from entering the site, and artificial tamping will be used around the settlement observation equipment.

Eight. Settlement observation of surcharge preloading

8. 1 Embedding of settlement observation piles According to the requirements of design drawings, settlement observation piles are set up, and settlement and displacement of the whole subgrade line are observed according to the design section. When preloading soil is loaded, the measuring rod of the line center settlement observation plate should be connected to 10cm above the top surface of preloading soil. At the same time, a temporary settlement plate is set on the top surface of the bottom of the foundation bed, and the measuring rod of the temporary settlement plate and the filling height of the preloading soil are connected to the top surface of the preloading soil. The top surface of preloading soil shall not be greater than 10cm. The specific layout is: there are 1 * * 3 temporary settlement plates on the left, middle and right of each section, and the middle temporary settlement plate and foundation settlement plate are located in the center of subgrade. It is stipulated that the middle temporary settlement plate should be set at the basement settlement plate 1m and marked with red paint to observe the settlement of subgrade surface. When loading soil, protect the settlement observation tube. Surround the settlement observation tube with soil first, and then load the remaining soil to prevent mechanical collision with the settlement observation tube.

8.2 Settlement observation

During the layered filling of preloading soil and the preloading period after filling, detailed settlement observation should be carried out according to the frequency required by the design. After the specified preloading time (at least 6 months) is reached, the post-construction settlement is analyzed, the settlement is analyzed and evaluated, and the unloading is carried out after the requirements are met. The settlement observation group is responsible for settlement observation. From the beginning of loading construction, the observation frequency of settlement observation during preloading period is as required: the first month 1 time/week, the second and third months 1 time/week, and the third month 1 time/month.

8.3 Analysis and evaluation of settlement data

According to the design documents, combined with the actual settlement of subgrade and the requirements of the whole project period, the preloading period of surcharge is not less than 6 months. The unloading time of surcharge preloading shall be determined by the design, supervision and construction unit of the construction unit according to the observation data and the calculation results of post-construction settlement. If the settlement deformation of subgrade still does not converge at the settlement expiration date, contact the supervisor, designer and owner in time, and negotiate with them to take corresponding measures such as extending the preloading period, so that the post-construction settlement can finally meet the requirements of track laying.

After sorting out the original data of field investigation, list calculation, and then analyze the calculation results. When the settlement is stable, it can be unloaded. On the contrary, if the settlement is unstable, it is necessary to continue preloading. Unloading can be carried out after preloading is stable.

8.4 Dynamic Control Report of Settlement Observation

During preloading, the measured data should be carefully analyzed and compared according to the settlement observation results of each month, and the dynamic control report of settlement observation should be submitted. The contents of the report include: the progress of the project, the standard working state of settlement, the analysis of settlement observation results and the relationship curve between filling process and settlement of foundation treatment methods in typical working geological sections. Through the conclusion of the report, fully understand the current project progress and the implementation of preloading section, determine the unloading section and non-unloading section, and control the construction of preloading section in time. At the same time, through the analysis of the settlement process of typical sections, the settlement and stability process of the subgrade of the whole preloading section can be grasped in time and accurately.

Nine, unloading and settlement filling

9. 1 uninstall

After the settlement data is evaluated, the preloading soil can be unloaded, then loaded with loaders and transported to the dump by dump trucks. During mechanical construction, the thickness of 20cm shall be reserved, and the rest shall be removed manually to prevent pollution and damage the integrity and stability of the bottom bed. Finally, clean the geotextile.

9.2 settlement filling

Measure the top surface of the bottom layer of the foundation bed from which the preloading soil has been removed, and compare the measurement results with the design elevation. If the height difference after settlement is above 10cm, group B can be used for filling. When the height difference after settlement is within 10cm, Group B materials shall not be used for filling, sand cushion isolation layer shall be built, and the height difference part shall be filled with bed surface graded macadam.

X. Safety protection measures

10. 1, strengthen the concept of safety legal system, strictly implement the written disclosure of safety work recognized by both parties, and adhere to the system of holding safety operation certificates for special types of work.

10.2, the use of construction machinery in strict accordance with the relevant provisions, irrelevant personnel are strictly prohibited.

10.3, strengthen the safety assessment of construction management personnel, enhance safety awareness and avoid illegal command.

10.4, assign a special person to command the mechanical operation, and the dump truck should follow a unified route when walking.

10.5, all on-site electrical equipment is used as leakage protection device, and the distribution line adopts three-phase five-wire system.

10.6, and adequate lighting equipment shall be provided for night construction.

1 1.7. A safety fence should be built around the borrow pit, and corresponding safety warning signs should be set.

XI。 Environmental protection measures

1 1. 1. Comply with national and local regulations on soil and water conservation and take necessary measures to prevent the pollution of rivers, lakes, ponds and reservoirs by harmful substances such as fuel, oil, asphalt, sewage, waste and garbage during construction.

1 1.2. Arrange the working procedures reasonably, make full use of subgrade waste, reduce the amount of soil taken, reduce soil erosion, and do a good job in slope protection to prevent landslides and collapses.

1 1.3, the preloading soil shall be filled as far as possible to avoid the rainy season. If the rainy season can't be staggered, the rain situation should be grasped in time during construction, and protective measures should be taken before it rains, so as to avoid easy erosion or the newly dug exposed surface being directly washed by rain; Prevent soil erosion caused by rain erosion.

1 1.4. The site selection of the spoil ground should be negotiated with the local government and combined with the unified land reclamation plan. Generally, we choose to avoid the large catchment valley on the hillside and the wasteland with gentle slope, build ballast retaining works in advance, and arrange intercepting and discharging facilities. During the construction period, rivers, waterways and existing irrigation and drainage systems shall not be damaged, occupied or disturbed. When the pressure must be occupied, the consent of the competent department should be obtained first, and necessary protective and alternative measures should be taken. Prevent the earth and stone excavated in the construction process from silting up or blocking the drainage systems such as rivers, waterways and irrigation canals.

1 1.5. When dumping soil and slag, the retaining wall (dam) and drainage facilities should be built first, then the slag should be discarded, and plant measures should be arranged after dumping.

Twelve, surcharge preloading quality control measures

12. 1 The preloading load should not be less than the design value;

12.2 The width and slope of precompressed soil shall meet the design requirements;

12.3 preloading soil should strictly control the loading rate, and the layered (horizontal) load should be in accordance with the design requirements to ensure the stability of the foundation under various loads. During preloading, the British side should bulldoze the soil and flatten it, and the local stacking load should not be too high;

12.4 take effective measures in strict accordance with the design requirements to prevent the preloading fill from polluting the subgrade during preloading filling;

12.5 During preloading, the settlement observation device should be well protected, and it should be repaired in time if it is damaged.

12.6 when the settlement of the pre-pressed subgrade meets the design requirements, the materials can be unloaded;

12.7 settlement observation shall be carried out with observation instruments meeting the accuracy requirements, and the curve of "filled soil height-time-settlement" shall be compiled and drawn for each observation result. During the construction period, the settlement should be observed once a day, and 2-3 times a day when the settlement increases sharply. After the embankment is filled in layers to reach the preloading height, it shall be observed every 5 days 2-3 months before the preloading period, every 7- 15 days after 3 months, and every 6 months thereafter until the preloading period ends.

12.8 surcharge rate control. When the rate of land subsidence of the center line of the embankment is greater than 10mm/ day and night, and the horizontal displacement of the toe of the slope is greater than 5mm day and night, the filling shall be stopped immediately, and the filling shall be carried out after the observed value is restored to the limit.

(See the next page for the construction process block diagram of surcharge preloading)

Block diagram of surcharge preloading construction technology

Gansu-Qinghai Section of Lanzhou-Xinjiang Railway Newly Built by China Railway No.9 Bureau

road

basis

many

load

advance

press

carry out

worker

square

situation

Gan Qing Section Project Manager Department of Lanzhou-Xinjiang Railway Newly Built by China Railway No.9 Bureau

20 10 year1October 3rd

Second Double-track Project of Newly-built Lanzhou-Xinjiang Railway (Gan Qing Section)

TA 1-3 construction organization design (scheme) submission form

Project name: construction contract of Gan Qing section of the second double line of newly-built Lanzhou-Xinjiang Railway: LXS- 13No. ：

To: Fourth Sub-station of Supervision Station of Gan Qing Section of Beijing-Lan Xin Railway:

According to the relevant provisions of the construction contract, our unit has completed the subgrade surcharge preloading construction organization design (scheme) of DK704+505.75438+0-DK715+750, and it has been reviewed and approved by the technical director of our unit. Please review it.

Contractor (seal)

project management

date

Supervision substation opinion:

Deputy Director of Supervision/Professional Supervision Engineer

date

Opinion of monitoring station:

Supervision Station (Seal)

Chief supervision engineer

date

Note: 1, this form is in quadruplicate, 2 for the contractor, 1 for the supervisor and 1 for the headquarters for reference.

2. This form is applicable to the examination and approval of construction organization design of general units in this bid section.

The second double-track project of the newly-built Lanzhou-Xinjiang Railway

Construction scheme of subgrade surcharge preloading in DK7 17+345-DK732+300 section

20 10 10 month

Construction unit: Project Management Department of Gan Qing Section of Lanzhou-Xinjiang Railway newly built by China Railway No.9 Bureau.

Prepared by:

Reviewed by:

Examiner:

Approver:

FYI