Soil nailing wall
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The collapsed building 7 is located near the street of section 7 of Wanghe Road, Gaoping District
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On the morning of August 3, the property and relevant units have been treated
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” On the afternoon of August 3, the reporter came to yujingwan community where Mr
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Considering the internal support conditions and the depth of the foundation pit, layered excavation must be carried out without special conditions, and the layered thickness shall be less than 2m
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At this time, the left soil slope can form a passive earth back pressure zone for the surrounding retaining structure, so as to enhance the stability of the retaining structure
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2.3 key points of lower layer earthwork excavation: after the strength of the first support reaches 80% of the design strength (the construction shall be carried out according to the instructions if there are independent requirements in the drawings), the lower layer earthwork excavation shall be started
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After the construction of concrete cushion, foundation or basement structure in the middle part is completed, use horizontal support or diagonal support to support the surrounding retaining structure, and suddenly excavate the soil in some passive soil areas in the surrounding retaining structure
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The slope excavation shall be provided with measures to reduce the water level in the pit and prevent the backflow of water outside the pit
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04 process flow ▲ earthwork excavation construction process flow ▲ general layered method construction process flow ▲ support layered method construction process flow ▲ reverse method earthwork excavation construction process flow ▲ central island excavation method construction process flow ▲ basin excavation method construction process flow 05 construction key points 1
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” The owners said that the collapse led to the rupture of sewage pipes and other pipelines
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However, the owners are more worried about the potential safety hazards such as foundation exposure caused by the collapse, which has not been replied yet“ What we can see is that the construction site pushes the soil back, but it has little effect
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1
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Basin excavation is to excavate the earthwork in the middle of the foundation pit in layers, and the soil within a certain range around the foundation pit will not be excavated temporarily, so as to produce basin effect
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The excavation sequence can be parallel excavation from one side of the foundation pit to the other, symmetrical excavation from both ends of the foundation pit, or parallel and symmetrical excavation from the middle of the foundation pit to both sides, or alternatively layered excavation, which can be determined according to the working face and soil conditions
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The first support and enclosure top ring beam are constructed along with the excavation to form an excavation trestle
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The soil within the whole foundation pit is excavated in a large area from the natural ground to the support bottom elevation in the first layer
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Supporting pile; 2
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In contrast to basin excavation, the central island excavation is to excavate the earthwork around the foundation pit first, and the earthwork in the center of the foundation pit is temporarily retained, so as to form an island soil pier at the central fulcrum
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The siege of the street section is under closed construction
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3
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General layered method construction key points 1.1 draw key points diagram and number construction key points: (1) site leveling elevation ；（ 2) Excavated platform（ 3) Excavated slope（ 4) Design excavation elevation
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The reporter contacted the Gaoping District Emergency Management Bureau, and the staff on duty said, “after the incident, the site has found geological disaster experts to investigate and demonstrate, and also made treatment plans such as overweight sandbags, cement pouring, pile driving and reinforcement.” Key points of earthwork excavation 01 overview the common methods of earthwork excavation include general layered method, support layered method, basin excavation method, central island excavation method and reverse method earthwork excavation, which can be selected according to specific conditions in the project
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Waist beam; 5
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Design elevation surface 2.2 key points of support surface excavation: in the earthwork excavation of foundation pit with internal support
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02 preparation instruction 03 construction preparation (1) check the axis and corresponding coordinates in the drawing, the layout of central line and horizontal base point is reasonable, and the axis setting out and elevation measurement meet the construction requirements（ 2) Laser measuring instrument shall be equipped, and elevation and dimension measurement shall be done in time before and during excavation（ 3) Before the construction of foundation pit works, carefully check the survey data of foundation pit design according to the construction design drawings, such as topography, landform, engineering geology, hydrogeology, drilling charts, etc（ 4) Find out the conditions of the project site, including transportation roads, adjacent buildings, pipelines, cable pit foundations, air raid shelters, obstacles and deposits within the construction scope on the ground, water supply, power supply, communication, flood control and drainage system, so as to provide reliable data and data for construction planning and preparation（ 5) Study and formulate the construction scheme of site leveling and foundation pit engineering; Prepare the general construction layout plan and foundation pit earthwork drawing, and determine the excavation route, sequence, scope, design elevation, slope gradient, drainage ditch, sump location, and excavated earthwork stacking place; Put forward plans for construction machines and tools, labor and promotion of new technologies
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We hope to carry out reinforcement treatment such as cement pouring as soon as possible
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Same as retaining wall; 4
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Gravity type; 5
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The grading value shall meet the specification requirements
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2.4 key points of excavation surface sealing construction: the excavation methods of lower support and soil are the same as those of upper inner support surface
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1.4 key points of excavated equipment construction: select appropriate mechanical supporting operation for excavated equipment according to the slope surface, speed up the construction progress, ensure excellent equipment performance and improve construction efficiency
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Under the soft soil foundation, it is not suitable to dig too deep, which is generally controlled at about 6 ~ 7m, and the hard soil layer is not subject to this restriction
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The foundation of a slope building in a community in Nanchong, Sichuan collapsed
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Construction key points of support layered method 2.1 draw the key points map and number the construction key points: the soil wall with internal support can be excavated vertically downward without a large site around the foundation pit, which can be used in the situation of narrow site and poor soil quality
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2
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The slope gradient of foundation pit shall be determined according to soil quality, foundation pit depth, excavation method, retention time, slope load, drainage and site size
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Key construction points of central island excavation method 4.1 draw key construction points and number them: this method can be used when the foundation pit area is small and the surrounding environment and soil can be anchored or supported
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Li, the owner of yujingwan community, Gaoping District, Nanchong City, reported to the media that the foundation and platform in the west of building 7 of the community collapsed twice from the evening of the 2nd to the early morning of the 3rd, resulting in the collapse of the wall at the bottom of the building, the protective fence and a green platform about 5m long
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“Collapse and landslide occurred outside the West platform and slope of building 7 in our community.” On the morning of August 3, Mr
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Soil anchor rod; 4
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1.2 key points of layered thickness Construction: soft soil foundation shall be controlled within 2m; The hard soil can be controlled within 5m
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Attention shall be paid to the process support, and the excavation surface of the current layer shall be closed in time
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“The sewage pipeline was also broken
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Support for subsequent construction; 4
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Construction method: 1
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Excavation surface of the first layer; 3
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Construction method: 1
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After excavation to the base elevation, the bottom slab concrete cushion shall be poured immediately
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The collapsed soil is still scattered at the foot of the slope, with cement blocks in the soil and scattered bicycles faintly visible
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Supports or engineering piles; 3
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Support one layer of horizontal top support for each excavation layer until the pit bottom, and finally pour the structural concrete of this part
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Mound
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Pull anchor type; 3
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1.3 key points of slope gradient construction: when slope excavation is adopted, the foundation pit slope is required to remain stable during construction
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3.2 key points of basin slope construction: during excavation, the slope can be made according to the soil conditions
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4
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Trestle; 2
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At the same time, after the underground structure is completed, the workload of foundation pit earthwork backfilling is also small
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Li is located
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Cantilever type; 2
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Key construction points of basin excavation method 3.1 key construction points of drawing key drawing: basin excavation method is suitable for foundation pit with large foundation pit area, difficult support or anchor pulling operation and unable to slope
Now the foundation is directly exposed, and some foundations are still suspended, It’s dangerous
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The first layer of earth excavation is generally excavated by large excavator
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At the bottom of building 7, some pipelines are exposed, the foundation of the collapsed building is exposed, and there are no warning signs around“ After the collapse, the property and the street community where the community is located conducted a visit and investigation for the first time, and the relevant departments also came to investigate
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” According to the construction announcement of road closure in Section 7 of Wanghe Road, the construction site at the collapse is the construction site of emergency material reserve in Gaoping District
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4.2 key points of layered thickness Construction: the reserved earthwork in the middle can be used as a fulcrum to set up a trestle, the excavator can use the trestle to go down to the foundation pit for soil excavation, and the soil transporting vehicle can also use the trestle to enter the foundation pit for soil transportation, which can effectively speed up the speed of soil excavation and transportation.
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