Rectangular working well with preset pipe jacking hole and sliding back wall in water-rich stratum and construction method thereof

A construction method of a rectangular working well with a preset pipe jacking hole and a sliding back wall in a water-rich stratum, comprising steps of:

• (I) designing functional requirements for the rectangular working well, comprising steps of:
• (1) collecting relevant data to determine a plane size, a depth, and a treatment method of a working well bottom cover, so as to satisfy well operation requirements;
• (2) determining a height and a diameter of the preset pipe jacking hole according to a position, a diameter, a material and a connection method of a proposed pipeline, wherein a quantity of the preset pip jacking hole is at least one;
• and
• (3) calculating and drawing a structure of the rectangular working well:
• using comparative calculation analysis of a rod system element method and numerical simulation to obtain an optimal supporting structure composition of the rectangular working well, and then drawing to complete functional requirement design for the rectangular working well;
• (II) constructing a caisson of an enclosing structure of the rectangular working well, comprising steps of:
• (1) preparing before construction of the caisson:
• comprising site leveling, laying out, excavating earth of a first layer, compacting a foundation, leveling and laying out, inspecting lines, laying a sand cushion, forming cutting edge formwork, binding steel bars, forming well body formwork, pouring concrete, curing, and demoulding;
• (2) constructing the caisson by sections:
• comprising preparing, installing a vertical transportation machinery and drainage pumps, observing, correcting, sinking to a designed elevation by sections, and verifying the elevation;
• (3) setting a thin concrete wall having a cavity along a vertical axis where the preset pipe jacking hole is located during pouring the caisson by sections, and inserting a sandwich concrete slab wall into the thin concrete wall having the cavity;
• and
• (4) using reinforced concrete or steel members as a material of the enclosing structure of the rectangular working well, and performing anticorrosive measures;
• (III) constructing an edge protector:
• setting embedded parts during construction the caisson of the enclosing structure of the rectangular working well, and connecting the edge protector and the embedded parts by bolts;
• (IV) excavating earthwork of the rectangular working well:
• during construction of the caisson, directly excavating the earthwork above water, and excavating the earthwork below the water by high-pressure water gun loosening, hydraulic grabbing or reverse circulation pumping;
• (V) forming a bottom cover for the rectangular working well, and pre-embedding a sliding track, a pull ring and a back wall anchor:
• in order to meet needs of subsequent construction, using concrete to treat the bottom cover of the rectangular working well;
• using plain concrete for anti-floating stability before connecting a caisson wall with reinforced concrete;
• simultaneously pre-embedding the sliding track, the pull ring and the back wall anchor during pouring the reinforced concrete bottom cover;
• (VI) installing a ladder for entering the rectangular working well:
• according to needs of subsequent maintenance, designing the ladder which is installed on an internal wall of the rectangular working well by planting bars;
• (VII) preventing joint leakage:
• using a polymer material for leakage control at joints of the rectangular working well and side walls of the caisson of the enclosing structure;
• (VIII) installing a water-proof pressure plate at an entrance of the preset pipe jacking hole:
• fixing the water-proof pressure plate at the entrance through expansion bolts according to a position of the preset pipe jacking hole;
• (IX) constructing the sliding back wall:
• according to a calculation result of a pipe jacking thrust, hoisting the sliding back wall, and fixing the sliding back wall by the back wall anchor;
• installing a pull rod between the back wall anchor and the pull ring;
• for different pipe jacking positions, adjusting a position of the sliding back wall through the pull rod and starting pipe jacking again after fixing;
• (X) lifting the sandwich concrete slab wall at a top of the preset pipe jacking hole:
• lifting the sandwich concrete slab wall to form the thin concrete wall having the cavity at the preset pipe jacking hole, so as to reduce a resistance when a pipe jacking machinery passes through the preset pipe jacking hole;
• and
• (XI) performing pipe jacking:
• after the pipe jacking machinery is installed in place, continuously passing through the thin concrete wall having the cavity at the preset pipe jacking hole under a hydraulic jacking thrust for normal pipe jacking construction.