Research On Key Technology Of Freeze Sinking Method For Alluvium With Thickness And Its Application

Freeze sinking method for alluvium with thickness exceeding 500m is a major technical difficulty attracting many researchers at home and abroad, and still at the exploratory stage. Aiming at the key problem of freeze sinking method for alluvium with extra thickness in Zhaogu mining area, theoretical calculation, laboratory test, numerical simulation and field measurement were employed.The computing formula for the thickness of the freezing wall of alluvium with extra thickness and its key parameters were proposed, and the computation system of the thickness design of the freezing wall of alluvium with extra thickness was established solving the problem of the freezing wall design of alluvium with thickness exceeding 500m, and the new scientific technology with several circles of freeze holes was proposed. High-efficiency and high-strength concrete of 80-90MPa compressive strength was developed using the field materials solving the problem of the high-performance concrete used in the freeze sinking method for alluvium with extra thickness as shaft wall.By using FLAC3D, modeling the construction steps of 512m clay layer controled,three-dimensional numerical calculations for the freezing wall stability were carried out. forecasts the freezing wall stability and instructs the design and construction,also, the displacement of especially thick alluvium freezing wall, the freezing wall temperature, shaft lining temperature and the actual freezing pressure research were launched. The form characteristic of the multi-circle hole freezing wall was grasped,proposes grouting theory before freezing wall and the calculation mothed of inner well wall thickness according to grouting pressure.obtains the value of freezing pressure in the condition of different depth, succeeds the application and the technical economic efficiency is remarkable.