A kind of construction method of sealing space enclosing structure of soft foundation building foundation pit
Technical field
The present invention relates to a kind of construction method of foundation pit enclosure structure, especially a kind of construction method of sealing space enclosing structure of soft foundation building foundation pit.
Background technology
At present in building foundation pit soil excavation engineering, generally forming one continuous body of wall around the edge of foundation ditch with engaged cement mixing pile or high-pressure rotary jet grouting pile makes water-stop curtain, cement mixing pile or high-pressure rotary jet grouting pile start from ground to enter the hypotonicity argillic horizon under foundation ditch downwards, make the fluid-tight space of the inner formation of foundation ditch.
The basic execution conditions of cement mixing pile or high-pressure rotary jet grouting pile are that levelling of the land, the soil body are even, neither too hard, nor too soft, cannot on the rock ballast layer that has the foreign material such as ratchel, construct; And in the construction place of the soft foundation such as marsh, coastal tidal land, argillic horizon is deep, physical features is low and groundwater table is high, while making construction land, need to build the thicker rock ballast layer of the ground backfill at place, place and building to raise the absolute altitude in place, thereby provide condition for construction.Carry out with this understanding in the excavation construction process of building foundation pit the effect of the water-stop curtain particular importance that seems.But because cement mixing pile or high-pressure rotary jet grouting pile almost cannot be at such field constructions, therefore such soft foundation building foundation pit suitable water stop curtain structure without comparison.
Summary of the invention
Technical problem to be solved by this invention is to provide the construction method of the sealing space enclosing structure of the soft foundation building foundation pit of a kind of convenient construction and energy conservation.
The present invention solves the problems of the technologies described above adopted technical scheme: a kind of construction method of sealing space enclosing structure of soft foundation building foundation pit, comprises the following steps:
it is the rock ballast layer of 2m ~ 6m that thickness is set on the soft foundation that needs construction foundation pit;
the edge of the foundation ditch of constructing around needs excavates groove downwards from the surface of rock ballast layer, until the degree of depth of institute's digging groove reaches hypotonicity argillic horizon;
in groove, fill homogeneous clay formation clay water-stop curtain;
in clay water-stop curtain, retaining wall in foundation pits is installed, the inner side of retaining wall in foundation pits and outside are fixed by the compacting of homogeneous clay;
in the foundation ditch being surrounded by retaining wall in foundation pits, horizontal support is set, completes the construction of sealing space enclosing structure.
Described groove is inverted trapezoidal structure.Prevent the sidewall generation avalanche of groove.
The bottom of described groove is 0.5m ~ 1.0m to the vertical distance of the bottom of described rock ballast layer, and the outside of described retaining wall in foundation pits is 0.6m ~ 1.2m to the horizontal range of the bottom outside of described groove.The bottom that guarantees groove is arranged in hypotonicity argillic horizon, makes the clay water-stop curtain between retaining wall in foundation pits outside and trenched side-wall play good stagnant water effect.
The slope angle of the sidewall of described groove is 45 ° to 75 °.Effectively prevent the sidewall generation avalanche of groove.
Described retaining wall in foundation pits is made up of the steel sheet pile of the edge setting of multiple foundation ditches around needs constructions or concrete drilling bored concrete pile or precast concrete pile.Adopt homogeneous clay as clay water-stop curtain, for the retaining wall in foundation pits of existing various species provides favourable construction environment, convenient and quick construction.
Compared with prior art, the invention has the advantages that the degree of depth of groove reaches hypotonicity argillic horizon, guaranteed that the clay water-stop curtain between retaining wall in foundation pits outside and trenched side-wall plays good stagnant water effect; Clay water-stop curtain does not need maintenance operation after construction, constructs completely just can produce stagnant water effect at once, meanwhile, and excavation groove and to fill the work progress of homogeneous clay convenient rapidly, the construction period shortens greatly; Homogeneous clay can, from excavating on the spot near job site, without using extra power, reduce construction cost.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention.
The specific embodiment
Below in conjunction with accompanying drawing, embodiment is described in further detail the present invention.
Embodiment mono-: a kind of construction method of sealing space enclosing structure of soft foundation building foundation pit, comprises the following steps:
it is the rock ballast layer 1 of 6m that thickness h is set on the soft foundation that needs construction foundation pit.
the edge of the foundation ditch of constructing around needs excavates from the surface of rock ballast layer 1 groove that is inverted trapezoidal structure downwards, until the degree of depth of institute's digging groove reaches hypotonicity
argillic horizon 2, the bottom of groove is 0.5m to the vertical distance d of the bottom of rock ballast layer 1, and the slope angle of the sidewall of groove is 45 °.
in groove, fill homogeneous clay formation clay water-
stop curtain 3.
retaining wall in foundation pits 4 is installed in clay water-
stop curtain 3, the inner side of retaining wall in foundation pits 4 and outside are fixed by the compacting of homogeneous clay, the outside of retaining wall in foundation pits 4 is 0.9m to the horizontal range s of the bottom outside of groove, and retaining wall in foundation pits 4 is made up of the precast concrete pile of the edge setting of multiple foundation ditches around needs construction.
horizontal support 5 is set in the foundation ditch being surrounded by retaining wall in foundation pits 4, completes the construction of sealing space enclosing structure.
Embodiment bis-: remainder is identical with embodiment mono-, its difference is that the thickness h of rock ballast layer 1 is 2m, the bottom of groove is 1.0m to the vertical distance d of the bottom of rock ballast layer 1, the slope angle of the sidewall of groove is 75 °, the outside of retaining wall in foundation pits 4 is 1.1m to the horizontal range s of the bottom outside of groove, and retaining wall in foundation pits 4 is made up of the concrete drilling bored concrete pile of the edge setting of multiple foundation ditches around needs construction.
Embodiment tri-: remainder is identical with embodiment mono-, its difference is that the thickness h of rock ballast layer 1 is 4m, the bottom of groove is 0.7m to the vertical distance d of the bottom of rock ballast layer 1, the slope angle of the sidewall of groove is 60 °, the outside of retaining wall in foundation pits 4 is 0.6m to the horizontal range s of the bottom outside of groove, and retaining wall in foundation pits 4 is made up of the steel sheet pile of the edge setting of multiple foundation ditches around needs construction.