3.
(3) When a bulldozer is used to excavate a large foundation pit (groove), the soil shall generally be pushed from both ends or top (longitudinal) to push the soil to the middle or top; Pile up temporarily, and then push the soil laterally away from both sides of the pit (groove).
Operation process flow: determine the excavation sequence and slope → excavate evenly in sections and layers → trimming and bottom cleaning (1) determination of slope: 1) when excavating foundation pit (groove) and pipe trench in naturally humid soil, when the excavation depth does not exceed the following values, there can be no slope and support.
If the geological conditions are good, the soil (rock) quality is relatively uniform, and the height is within 10m, the slope gradient of the temporary excavation slope shall be determined according to table 1-312.
(a) Dense and medium dense sand or gravel soil (filled with sand) – 1.0m; (b) Hard plastic and plastic light loam and loam – 1.25m; (c) Hard plastic and plastic clay and gravel soil (filled with cohesive soil) – 1.5m (d) hard clay – 2.0m.
(4) When excavating a large foundation pit (groove) with a scraper, it shall be excavated vertically in branches and layers and downward according to the slope line, but the central section of each layer shall be slightly higher than both sides to prevent ponding.
(5) When backhoe and dragline excavator are used to excavate the foundation pit (groove) or pipe trench, there are two construction methods: 1) end excavation method: the excavator excavates from the end of the pit (groove) or pipe trench in a backward way.
(2) When excavating the foundation pit (groove) or pipe trench, the excavation sequence, route and excavation depth shall be reasonably determined, and then the excavation shall be carried out in sections and layers.
(3) During night construction, there shall be sufficient lighting facilities: obvious signs shall be set in dangerous sections, and the excavation sequence shall be reasonably arranged to prevent wrong excavation or over excavation.
(2) The location of buildings or structures or the positioning control line (pile) of the site, the standard horizontal pile and the gray line size of slotting must pass the inspection, and the pre inspection procedures must be completed.
Main machines and tools (1) earth moving machinery: excavator, bulldozer, scraper, dump truck, etc.
2) Lateral excavation method: one side of the excavator moves along the pit (groove) side or one side of the pipe trench, and the dump truck loads the soil on the other side.
(5) The roads, bridges and unloading facilities passed by construction machinery entering the site shall be inspected in advance, and preparations such as reinforcement or widening shall be made if necessary.
2) When the depth exceeds the above specified depth and is within 5m, when the soil has natural humidity, uniform structure, good hydrogeological conditions, and there is no groundwater, the foundation pit (groove) and pipe trench without support must be sloped.
1.
Category of soil in the item: slope gradient (height: width) no load on the top of the slope, static load on the top of the slope, 1 medium dense sandy soil on the top of the slope, 1:1.001:1.251:1.502 medium dense gravelly soil (filled with sandy soil), 1:0.751:1.001:1.253 hard plastic light loam, 1:0.671:0.751:1.004 medium dense gravelly soil (filled with cohesive soil) 1: 0.501:0.671:0.755 hard plastic loam, clay 1:0.331:0.501:0.676 old loess 1:0.101:0.251:0.337 soft soil (after well point precipitation) 1:1.00 – note: when there is mature construction experience, it may not be limited by this table.
(6) The selection of earth moving machinery shall be comprehensively considered according to the terrain and operating conditions of the construction area, soil type and thickness, total quantities and construction period, so as to give full play to the efficiency of construction machinery, and prepare the construction scheme.
2.
(7) The layout of the operation route in the construction area shall be determined according to the size of the work area, mechanical performance, transportation distance and topographic relief.
(6) When the excavator moves along the excavation edge, the width of the machine from the upper edge of the slope shall not be less than 1 / 2 of the depth of the foundation pit (groove) and pipe trench.
(8) Where mechanical construction cannot be carried out, slope trimming and cleaning shall be carried out manually.
4) When the excavation passes through different types of soil (rock) layers or the depth exceeds 10m, the slope can be made into broken line shape or step shape.
The steepest slope of the slope shall comply with the provisions in table 1-311.
The dump truck is configured on both sides of the excavator to load soil.
(4) When excavating the foundation pit (groove) and pipe trench with underground water level, measures shall be taken to reduce the underground water level according to the local engineering geological data.
3) The slope gradient of temporary earth excavation slope used for a long time shall be determined according to the engineering geology and slope height and in combination with the stable slope value of local similar soil mass.
Operating conditions (1) before earth excavation, the underground and aboveground obstacles in the construction area shall be removed and treated according to the requirements of the construction scheme.
Excavation slope gradient of various soils ＾ table 1-312 classification of soil ＾ slope gradient (height: width) 1 sandy soil (excluding fine sand and silt): hard 1:1.25 ~ 1:1.51:0.75 ~ 1:1.002 general cohesive soil; Hard plastic filling hard and hard plastic cohesive soil 1:1.00 ~ 1:1.151:0.50 ~ 1:1.003 gravel soil: filling sand 1:1.00 ~ 1:1.50 note: when there is mature construction experience, it may not be limited by this table.
(2) general machines have Spades (two kinds of shovel and flat head), trolley, small white line or 20 lead wire and 2m steel tape, slope ruler, etc.
Generally, it shall be lowered to 0.5m lower than the excavation surface before excavation.
(7) During excavation, the state of groove wall and slope shall be checked at any time..
If the excavation depth exceeds 5m, it shall be determined according to the professional construction scheme.
Mechanical excavation this technical disclosure is applicable to large foundation pits (grooves), pipe trenches, large-area leveling sites and other earthworks of industrial and civil buildings and structures.
