Deep foundation pit supporting construction units should achieve fine management, no matter excavating soil, retaining soil, enclosure, precipitation and other construction links may lead to major safety accidents, especially the collection, sorting and analysis of geological survey reports and monitoring data, need to be seriously implemented to ensure the safe and orderly operation of the project construction.
Definition of deep foundation pit engineering:
1, the excavation depth exceeds5m(containing5m)The foundation pit (slot)Earthwork excavation, support and precipitation engineering.
2The excavation depth has not exceeded5m, but the geological conditions, surrounding environment and underground pipelines are complex, or affect the adjacent buildings(To construct )Safe foundation pit(slot)Earthwork excavation and support.
deepFoundation pit supporting Construction form
1, row pile support
It is usually composed of retaining pile, support (or soil anchor) and impermeable curtain. The pile row can be divided into cantilever support structure, pull-anchor support structure, inner bracing support structure and bolt support structure according to the construction situation.
Applicable conditions: foundation pit sidewall safety level for the first, second, third; It is suitable for foundation pit with dewatering or water stop curtain.
2Soil nailing wall support
Soil darn wall is made of natural soil reinforced in situ through soil darn wall and combined with jet darn to form a gravity-like retaining darn to resist the earth pressure behind the wall. In order to maintain the stability of the excavation face, this soil retaining wall is called soil nail wall. Soil nail wall is set by drilling, inserting reinforcement, grouting, generally called mortar bolt, can also be directly driven into Angle steel, thick steel to form soil nail.
3, bolt support
Bolt support is a kind of reinforcement and support method used in surface engineering such as slope, deep foundation pit and underground chamber construction such as tunnel and stope. Use of the polymer and metal parts, wood or other material, pole into the surface of the rock mass or cavern surrounding rock mass in the drilled holes in advance, to use its head, the special structure of the rod body and tail plate (or not), or depends on the bonding together and stability of rock mass surrounding rock and suspension effect, effect of composite beams, the effect of reinforcement, in order to achieve the purpose of supporting. It has the advantages of low cost, good supporting effect, simple operation, flexible use and less construction clearance.
4, retaining pile and soil anchor combined support
No anchor pile or tie rod shall be set at the pile top.Instead, it is dug to a certain depth, and anchors are driven diagonally into the back of the pile every certain distance. When the strength is reached, the transverse support is installed, the tension is fixed, and the soil is dug in the middle of the pile until the design depth is suitable for large deep foundation pit, the construction period is long, and the adjacent buildings are not allowed to support, and the adjacent foundation is not allowed to have subsidence displacement.
5Steel sheet pile support
Steel sheet pile is a type of steel with a lock, and its section has straight plate shape, groove shape andZShape, available in various sizes and interlocking forms. The common ones are Larsen style, Lackawanna style, etc. Its advantages are: high strength, easy to drive into the hard soil; Can be used in deep water construction, if necessary, diagonal support to become a enclosure. Good waterproof performance; Cofferdam can be composed of various shapes according to needs, and can be repeatedly used, so it has a wide range of uses.
6, underground diaphragm wall support
Underground continuous wall is a foundation engineering on the ground using a chamfered machinery, along the deep excavation engineering around the axis, under the condition of slurry-supported excavation of a long and narrow deep groove, after the qing tank, sling the reinforcing cage in the tank, and then placing underwater concrete by catheter method a unit slot, so piecewise, underground built a continuous reinforced concrete wall, As a water intercept, seepage, bearing, water retaining structure.
7, retaining wall,＋Stay within the supporting
When the depth of the foundation pit is large, the strength and deformation of the cantilever retaining wall cannot meet the requirements, and the reliability of the anchor pulling outside the pit is low, the inner support can be used in the pit. It is suitable for all kinds of foundation soil, the disadvantage is that the inner support will occupy a certain construction space, but according to the development of technology, now the occupation of the inner support will not affect the excavation and construction of the foundation pit. The newly developed prefabricated steel support, steel tube inner support and reinforced concrete frame inner support are commonly used.
(1) Prefabricated steel support (occupying minimum pit construction space)
(2)Steel pipe support
(3)Reinforced concrete support
deepFoundation pit supportingConstruction units should achieve fine management, no matter excavating, retaining, enclosure, precipitation and other construction links may lead to major safety accidents, especially the collection, sorting and analysis of geological prospecting reports and monitoring data, need to be conscientiously implemented to ensure the safe and orderly operation of the project construction.
Shanghai Qiangqiang Foundation Engineering Co., LTD. 's business covers foundation pit engineering, pile foundation engineering, land and waterFoundation treatment, slope treatment and other engineering fields. around "Excellent technology, reliable process, fast construction" technical requirements, is to provide customers with land, water foundation engineering technical consultation, construction services and other comprehensive solutions of the entity enterprise. Contact Number:400-100-2850
