REINFORCEMENT STRUCTURE FOR ENTRY AND EXIT OF LARGE-DIAMETER JACKING PIPE GROUP IN WATER-RICH SAND STRATUM, AND CONSTRUCTION METHOD

A reinforcement structure for entry and exit of a large-diameter jacking pipe group in a water-rich sand stratum, and a construction method. The structure comprises underground diaphragm walls (2) and high-pressure jet grouting piles (5); the underground diaphragm walls (2) are arranged at edge positions of a launch shaft (9) and a reception shaft (10); the depths of the underground diaphragm walls (2) are below a bottom elevation of a pipe jacking machine; bored piles (4) are provided at the middles on the insides of the launch shaft (9) and the reception shaft (10); the depths of the bored piles (4) are the same as those of the underground diaphragm walls (2); cross braces (3) are used between the underground diaphragm walls (2) for support; the cross braces (3) are fixedly connected to the bored piles (4); the high-pressure jet grouting piles (5) are provided at the entry and exit of a jacking pipe group and the outside of the underground diaphragm walls (2); the high-pressure jet grouting piles (5) are ar