1. 1 earthwork excavation

Overview 1. 1. 1

Scope and content of work 1. 1. 1

The excavation of this project mainly includes foundation cleaning excavation and culvert excavation. Among them, the foundation is cleaned and excavated m3, and the culvert is excavated m3. See table 3- 1 for the statistics of quantities.

Table 3- 1 Statistics of Earthwork Excavation

Project name Total amount of earthwork excavation

Clear foundation excavation

Culvert gate excavation

total

The earthwork excavation of this project mainly includes the foundation excavation of the newly-built dike body and the earthwork excavation of the tank intake sluice. Earthwork excavated in this project, if it meets the requirements of filling soil materials, can be used to fill the new embankment, and then transported to the backfill yard for future embankment filling. If it does not meet the requirements of filling, it shall be transported to the designated place according to the requirements of the supervision engineer.

1. 1. 1.2 main technical requirements

(1) The vegetation clearing scope is the maximum excavation boundary shown in the design drawings approved by the project or the horizontal distance of 3m outside the building foundation;

(2) Unqualified dirt and sundries on the foundation surface must be removed;

(3) A proper protective layer must be left above the foundation surface, which can only be leveled by manual excavation, and the undisturbed soil of the foundation cannot be protected by mechanical excavation;

(4) Waste soil, sundries, waste residue, etc. Materials for foundation cleaning, excavation and removal shall be piled up at the designated place;

(5) The actual excavation contour must meet the requirements of design drawings or the opening line, horizontal size and elevation specified by the supervision engineer on site, and the final excavation contour shall not be under-excavated.

(6) When excavating earthwork near residential areas, take effective measures to ensure the safety of residents and construction workers, and provide effective temporary access roads or temporary bridges for the lives of nearby residents.

1. 1.2 construction layout

1. 1.2. 1 wind, water and electricity layout in the construction area

The lighting for earthwork excavation construction is planned to be dominated by floodlights, supplemented by iodine tungsten lamp and incandescent lamps in some areas, and waterproof high-pressure sodium lamps will be used for roads during construction; The production water consumption of excavation construction is small, so it can be directly extracted from the river by submersible pump and connected to the water working face by hose.

See the general layout of construction for details of water supply and power supply arrangement in the construction area.

1. 1.2.2 Construction road layout

The temporary road for the whole earthwork excavation construction of this contract project is planned to adopt a mud-rock pavement with a width of 6m. See the general layout of construction for details of road layout.

1. 1.3 earthwork construction sequence

Earthwork excavation of this project shall be carried out in sections according to the construction site. During the construction of each section, according to the length of the excavation unit, the strip method is used for division and cleaning, and one section is excavated after cleaning. After the excavation section of a construction unit is completed, follow-up works such as slope protection will be carried out, and the excavation construction will be moved to the next unit section. Each unit shall be excavated downward layer by layer according to the excavation section.

According to the site survey and the progress plan of this tender document, the earthwork construction and earthwork allocation shall be arranged reasonably, and the excavated materials shall be directly used for filling as far as possible, and the excavation and filling shall be constructed in parallel as far as possible, so as to reduce the construction process of filling materials.

1. 1.4 construction preparation

1. 1.4. 1 survey and sideline lofting

According to the layout of the survey control network, the total station, theodolite and level are used for putright. First, the total station and theodolite are used to release the construction baseline, and then all the control sideline lines are released according to the relevant dimensions on the design drawings. The elevation is controlled by level, that is, the adjacent elevation points arranged in the front are taken as the rear viewpoint, and the elevation control lines are released respectively.

Before the excavation, the original topographic survey report should be submitted to the engineer, and after the excavation is completed, the application for completion survey should be submitted to the supervision engineer for review.

1. 1.4.2 technical preparation

Before construction, according to the supervision instructions and construction drawings, prepare the construction measures plan of this project and submit it to the supervision engineer for review.

Before construction, make technical disclosure, get a detailed understanding of engineering geological structure, topography and hydrogeology, and take preventive and protective measures and emergency measures for possible landslides and collapses.

According to the requirements of the schedule and construction measures plan, organize the construction equipment and construction personnel to enter the site, and prepare and implement the material supply plan. According to the requirements of the site and the bidding documents, arrange the construction transportation roads reasonably, and do a good job in site planning, soil material balance planning, soil material transportation routes and night construction lighting. Before the construction of each part, detailed and feasible earthwork construction measures or construction schemes should be formulated.

1. 1.5 earthwork excavation

1. 1.5. 1 earthwork open-cut construction scheme

1.1.5.1.1vegetation cleaning and topsoil removal

Before excavation, clean up the vegetation in the excavation area, that is, remove roots, weeds, garbage, waste residue and other obstacles designated by the supervisor. Trees and weeds in the excavation area should be cut down manually and transported to the place designated by the supervision engineer for treatment. The scope of vegetation cleaning shall be at least 3.0m away from the outside of the excavation or backfill sideline. Vegetation cleaning mainly adopts 1.5m3 hydraulic backhoe, supplemented by manual cleaning in some areas.

Before topsoil cleaning, clean the surface sundries first, then clean the topsoil with 1.5m3 hydraulic backhoe, load the waste materials with backhoe, and transport them to the spoil ground with dump truck, so as to restore the environment after completion. At the same time, some wastes can be used as backfill materials to fill and reinforce ponds.

① The excavated organic soil should be piled up in the designated area (spoil ground) to prevent the soil from being washed away.

② The stored organic soil can be used for environmental protection and soil protection of the project.

1. 1.5. 1.2 earthwork excavation scheme

Earthwork excavation in this project adopts downward excavation layer by layer, which is carried out by layers according to the excavation section, and the height of layers is controlled below 5m. Earthwork excavation adopts 1.5m3 backhoe for direct excavation and transportation by dump truck. First, use backhoe to reserve 10 ~ 20 cm protective layer for mechanical slope repair, and then use manual excavation to repair the protective layer, so as to ensure that the earthwork of the slope is undisturbed, the slope is beautiful, and the slope and smoothness required by the construction drawings can be met.

All unused materials are transported to the spoil ground by excavator 15t dump truck, which can be directly transported to the backfill rolling area or transported to the excavation material preparation site outside the excavation area for temporary storage.

1. 1.5. 1.3 culvert foundation excavation

Special equipment should be arranged for culvert construction, and it can also be arranged to be interspersed with embankment earthwork construction under the condition of meeting the requirements of construction progress.

1. 1.6. 1 slag tapping, slag yard planning and slag utilization

1. 1.6. 1+0 slagging.

The slag is loaded by backhoe excavator, transported by dump truck, and leveled by bulldozer.

Excavated materials cannot be transported to the designated slag yard during unloading, those that can be used and can be directly used can be directly transported to the backfill area, and those that cannot be directly used can be transported to the material preparation yard.

1. 1.6. 1.2 Slag yard planning

According to the bidding documents and site survey, the slag yard is arranged at the place designated by the owner or supervision engineer.

1. 1.6. 1.3 slag yard protection measures

Do a good job in slag yard planning, slag abandonment planning and drainage facilities planning.

All excavated materials shall be directly transported to the place of use, and classified into material preparation yard, slag disposal yard or used for site leveling according to the drawings or the instructions of the supervision engineer. It is forbidden to pile soil near the opening line of adjacent slopes.

Slag should be stacked in layers, and dumping is strictly prohibited.

The stacking of materials in the material preparation yard should be carried out in layers according to the design requirements or the instructions of the supervision engineer, and this part of materials should be taken out and used smoothly. It is forbidden to mix selected materials with waste materials.

When the slag pile in the slag yard is getting higher and higher, and the effective area at the top of the slag yard is getting smaller and smaller, it is considered to build a masonry retaining wall around the slag yard, increase the slag pile in the slag yard, and restrict the slag yard within the specified range. Drainage holes are left on the retaining wall. Slag should be paved, stacked and lifted in layers to control the slope safety.

In order to ensure the drainage of the slag yard during the construction period, before filling, a slab culvert or a circular culvert covered with mortar stone shall be built in the ravine of the slag yard area, and the running water in the ravine shall be led to the river course or natural drainage ditch to ensure that the water collected by the mountain will not wash away the waste slag when backfilling the slag yard.

1. 1.6. 1.4 slag utilization rate

In this project, except for the surface cleaning of the dike slope, the waste soil needs to be transported to the waste soil field, and the rest of the excavated earth and stone need to be used to fill the dike body.

1. 1.7 construction drainage

1. 1.7. 1 temporary drainage for construction

Before excavation, intercepting ditches and drainage ditches should be excavated around the excavation area, and the running water formed by rainfall should be excluded from the excavation area. According to the precipitation in the construction area and the number of drainage ditches on site, the section size of drainage ditches is determined. Initially, it is trapezoidal, with slope ratio 1: 1, bottom width of 0.2m and depth of more than 0.3m. ..

During slope excavation, in order to protect the excavated slope from rain, before slope excavation, the upper intercepting ditch should be excavated as required. After being approved by the supervision engineer, it shall be implemented before slope excavation.

1. 1.7.2 Removing groundwater

In the process of site excavation, temporary ground drainage facilities should be provided, and the excavated ground should form a certain drainage slope, and temporary drainage pits and troughs should be set up to remove ground water to ensure earthwork excavation in dry land.

1. 1.7.3 geological treatment measures for foundation surface

(1) If there is a weak interlayer in the foundation surface, it should be reported to the supervisor and the design geological representative in time, and handled according to the opinions of the design and supervision. In general, the weak interlayer should be pried manually until it meets the design requirements.

(2) For the faults in the excavation area, professional and technical personnel should be sent to monitor, discover and report in time, and assist the design geological representative and supervision engineer to understand the site geological conditions, formulate treatment plans in time, and deal with them as required. The general solution is manual grooving, which is 1.5 times the fault width.

1. 1.7.4 excavation quality control

(1) The specification requires that survey and setting-out control should be carried out before, during and after excavation, so as to ensure that the excavation is carried out according to the design requirements of the construction drawing, avoid unnecessary overbreak and ensure the designed excavation contour;

(2) After the foundation surface is excavated to the design elevation, the cushion concrete shall be poured in time to ensure that the foundation surface is free from pollution and weathering;

(3) After excavation, report the unfavorable geological conditions on the foundation surface to the supervision engineer in time;

(4) The excavated slope shall be smooth and stable without steep slope. Regularly check whether the slope is stable, take necessary treatment measures when signs of possible collapse are found, and report to the supervision engineer to avoid slope collapse.

1. 1.7.5 Slope protection measures

(1) Manual excavation or clay woven bag shall be used to form intercepting ditch at 1 ~ 5m outside the excavation boundary to ensure that the slope will not be washed away by rain.

(2) The earthwork slope is pre-trimmed with backhoe, and the protective layer of 10cm is reserved. Finally, the slope is manually trimmed to ensure that the undisturbed soil is not disturbed.

(3) During the construction period, observe the slope at fixed points on a regular basis, find problems in time, and report to the supervisor to take timely measures to deal with them. Treatment measures must be approved by the supervisor before implementation.

(4) When seepage occurs on the slope, PVC pipes are used for diversion to control the erosion of seepage on the slope, resulting in landslides and collapses.

1. 1.7.6 Basic surface protection measures

(1) Take necessary measures for construction water or leakage to prevent it from soaking the foundation surface; The flood dike shall be excavated for a period of time, and the filling shall be accepted in time. In rainy days, it shall be protected by colored strips, so that it can be filled in time after rain.

(2) 10cm shall be reserved for the foundation surface, which shall be trimmed manually to ensure that it meets the design requirements;

(3) The foundation shall be delivered unit by unit, so as not to affect the subsequent construction.

1. 1.7.7 Construction measures in winter rainy season

1. 1.7.8 winter construction measures

In winter construction, when the unfinished earth embankment foundation and foundation pit are started, the surface of the excavation surface will be loose for 30-40cm, and raked flat as the insulation layer to prevent freezing; After the excavation, the surface layer shall be pre-covered with soil or covered with straw bags to loosen the soil, which shall be removed when the construction continues. Immediately after earthwork excavation, the superstructure shall be constructed to prevent the basement from freezing; In case of process intermittence, it shall be treated as winter protective measures. The amount of loose frozen soil at a time should be determined according to the digging ability and climatic conditions, and it should be continuously excavated and transported with the digging to avoid freezing again. Soil insulation should be carried out when backfilling the foundation pit to prevent the soil around the foundation and foundation pit from freezing.

When the construction temperature is low in winter, transportation has a great influence on the construction progress of earthwork excavation. Too low temperature will affect the normal use of vehicles and equipment and reduce the working efficiency of equipment. Special measures must be taken to ensure normal construction in winter. Construction roads are also the main factors affecting traffic. In winter construction, it is necessary to strengthen the maintenance of construction roads and take corresponding measures to ensure the smooth flow of construction roads.

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