Diversion shield tunnel traversing new sea dyke and foundation treatment method thereof

Abstract

The invention relates to a pilot shield tunnel which crosses a newly-built seawall and a ground treatment method. The pilot shield tunnel is formed by that a plurality of duct pieces are assembled by bolts in a circumferential mode; the corresponding positions of the duct pieces are preinstalled with consolidated filling injection ports and operating ports of a high-pressure jet grouting pile; a plurality of high-pressure jet grouting piles are arranged at a certain distance from the bottom part of the duct pieces and form a transition layer; a reinforcing layer is formed by the consolidated filling injection in the sludge of the pilot shield tunnel which is formed by the duct pieces; the ground treatment method comprises: a plastic draining board is adopted to carry out ground foundation; the corresponding positions of the duct pieces are preinstalled with consolidated filling injection ports and operating ports of the high-pressure jet grouting pile; when the pilot shield tunnel crosses at the lower part of the foundation of the seawall, the construction of high-pressure jet grouting pile is carried out in the soft soil of a lower horizontal layer of the tunnel through the operating ports of the high-pressure jet grouting pile; the bottom of the high-pressure jet grouting pile enters a holding layer; after the construction of the high-pressure jet grouting pile is completed, consolidated filling injection is adopted at the periphery of the shield tunnel, thus having the characteristics of effectively reducing after-construction settlement of the shield tunnel which encounters the lower horizontal layer of the deep soft soil when crossing the newly-built seawall so as to prevent the tunnel from being tension fracture in the lengthways direction and further have influence of taking and draining water, and effectively improving the transverse forced state of the shield tunnel so as to prevent damage caused by the concentrated force on a single duct piece.

Description

technical field [0001] The invention relates to a foundation treatment method for a water diversion shield tunnel crossing a newly built seawall used in conjunction with a seaside power plant, which can solve the post-construction problems that occur when the shield tunnel crosses a newly built seawall and encounters a deep and thick soft soil underlying layer. Settlement and stress concentration problems. Background technique [0002] At present, the economy in the east coast of my country is developing rapidly, and the demand for electricity is large. In order to meet the requirements of economic development in the region and improvement of people's living standards, the country needs to invest huge sums of money every year in the construction of large-scale thermal power plants. The site selection of large-scale thermal power plants should fully consider the convenience and economy of coal transportation, water intake and drainage, as well as factors such as land conserva...

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Problems solved by technology

[0003] Tidal flat mud has the characteristics of low foundation bearing capacity, high compressibility, low permeability coefficient, and slow consolidation speed. Building seawalls on it often results in large post-construction settlements. The key technology of crossing is how to eliminate the longitudinal fracture of the tunnel caused by the post-construction settlement of the seawall, thus affecting the normal water intake of the power plant

At present, the technical measure often used to solve this problem is to carry out grouting reinforcement in the underlying layer of the tunnel to reduce post-construction settlement. However, this solution is often applicable to shallow silt layers. When the silt is deep, the grouting effect is poor, and it is urgent to find a better foundation treatment method

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