A ring-shaped cofferdam and temporary pit excavation structure using tapered square pipes includes a plurality of tapered square pipes a trapezoidal cross-section, in which the plurality of tapered square pipes each have a coupling protrusion or a coupling groove formed in a longitudinal direction on a first side, the plurality of tapered square pipes each have a coupling protrusion or a coupling groove formed in the longitudinal direction on a second side, the plurality of tapered square pipes are assembled by coupling the coupling protrusions and the coupling grooves, a long side of two parallel sides of the trapezoid is disposed outside, and a short side is disposed inside.

A wall sinking construction method comprises retaining structures are first formed on two sides, corresponding to a groove body, of the wall body; then a section of wall body of a certain height is produced on the ground, and jacks and a supporting pile body are installed on the two sides of the bottom of the wall body that is supported by the jacks and the supporting pile body, the bottom of the wall body is suspended to form an excavation working space with a certain height; an underwater excavator is controlled remotely to excavate rock and soil in the groove body layer by layer; an elastic support having rollers is sandwiched between the retaining structures on the two sides of the wall body and the groove body to transfer and balance rock and soil pressure.

A wall sinking construction method comprises retaining structures are first formed on two sides, corresponding to a groove body, of the wall body; then a section of wall body of a certain height is produced on the ground, and jacks and a supporting pile body are installed on the two sides of the bottom of the wall body that is supported by the jacks and the supporting pile body, the bottom of the wall body is suspended to form an excavation working space with a certain height; an underwater excavator is controlled remotely to excavate rock and soil in the groove body layer by layer; an elastic support having rollers is sandwiched between the retaining structures on the two sides of the wall body and the groove body to transfer and balance rock and soil pressure.

A concrete inside interface processing structure for secant pile construction, including secant concrete pile, formed plain concrete pile, rotary jet grouting piles, steel mesh sheet, ribbed steel bar, Y-shaped connecting piece, reinforced concrete pile, and U-shaped connecting piece; drilled holes are arranged at intervals along axis of the formed plain concrete pile; the ribbed steel bar is anchored in each drilled hole; the steel mesh sheet is formed by connecting longitudinal bars and transverse bars, and driven into a soil body between the formed plain concrete piles; the concrete layer is formed by spraying concrete on the steel mesh sheet; the reinforced concrete pile is cast at outside of the formed plain concrete pile, and tangent to the formed plain concrete pile, and interlocked with the rotary jet grouting piles; the rotary jet grouting piles are tangent to the formed plain concrete pile or secant concrete pile.

A concrete inside interface processing structure for secant pile construction, including secant concrete pile, formed plain concrete pile, rotary jet grouting piles, steel mesh sheet, ribbed steel bar, Y-shaped connecting piece, reinforced concrete pile, and U-shaped connecting piece; drilled holes are arranged at intervals along axis of the formed plain concrete pile; the ribbed steel bar is anchored in each drilled hole; the steel mesh sheet is formed by connecting longitudinal bars and transverse bars, and driven into a soil body between the formed plain concrete piles; the concrete layer is formed by spraying concrete on the steel mesh sheet; the reinforced concrete pile is cast at outside of the formed plain concrete pile, and tangent to the formed plain concrete pile, and interlocked with the rotary jet grouting piles; the rotary jet grouting piles are tangent to the formed plain concrete pile or secant concrete pile.

A method for constructing an assembled recyclable rectangular working well with preset detachable door openings comprises steps of: (I) designing according to functional requirements for a rectangular working well; (II) constructing by supporting piles; (III) installing prefabricated top beam; (IV) edge protection construction; (V) alternate construction of earthwork excavation, retaining slabs and internal support breast beams; (VI) installing the ladder entering the rectangular working well; (VII) rectangular working well back cover; (VIII) demolition of the detachable subsection support piles in the door part and completing the construction of the assembled recyclable rectangular working well in the preset detachable door hole; (IX) after the operation in the well is completed, during the backfilling process of the rectangular working well, gradually recovering the working well components such as the retaining slab, the internal support girder, the prefabricated crown beam and the supporting piles.

A method for constructing an assembled recyclable rectangular working well with preset detachable door openings comprises steps of: (I) designing according to functional requirements for a rectangular working well; (II) constructing by supporting piles; (III) installing prefabricated top beam; (IV) edge protection construction; (V) alternate construction of earthwork excavation, retaining slabs and internal support breast beams; (VI) installing the ladder entering the rectangular working well; (VII) rectangular working well back cover; (VIII) demolition of the detachable subsection support piles in the door part and completing the construction of the assembled recyclable rectangular working well in the preset detachable door hole; (IX) after the operation in the well is completed, during the backfilling process of the rectangular working well, gradually recovering the working well components such as the retaining slab, the internal support girder, the prefabricated crown beam and the supporting piles.

A portable cofferdam system for isolating a working area from water such as a culvert. The portable cofferdam system generally includes a first sidewall and a second sidewall each having an interior side, an exterior side, an upper edge, a lower edge and a rear edge. A middle wall is connected to the sidewalls opposite of the rear edges of the sidewalls forming a substantially U-shaped structure. An opening formed between the rear edges of the first sidewall and the second sidewall to allow for positioning about or near the inlet of an object or area to be kept dry such as the inlet of a culvert.

A portable cofferdam system for isolating a working area from water such as a culvert. The portable cofferdam system generally includes a first sidewall and a second sidewall each having an interior side, an exterior side, an upper edge, a lower edge and a rear edge. A middle wall is connected to the sidewalls opposite of the rear edges of the sidewalls forming a substantially U-shaped structure. An opening formed between the rear edges of the first sidewall and the second sidewall to allow for positioning about or near the inlet of an object or area to be kept dry such as the inlet of a culvert.

The method is used for strutting brace legs in a quadrangular setup of a rim of brace legs. The method consists in that a spreader (3) is attached to one end of each brace leg (2), while an extendable tensioning unit (4) is attached to the other end of the same brace leg (2). Next, the brace legs (2) are set inside the excavation in such a manner that, in the excavation corners, the ends of the brace legs (2) terminated with spreaders (3) become coupled with the ends of the subsequent brace legs (2) terminated with tensioning units. Once all the brace legs (2) have been coupled with each other, the ends of the brace legs (2), with the spreaders (3) attached to them, are pressed against the sheet piles (1) in the excavation corners by means of tensioning units (4) attached to subsequent brace legs (2).