Construction method applied to frozen shaft safe and rapid excavating large and thick expansive clay layer

Abstract

Disclosed is a construction method applied to frozen shaft safe and rapid excavating large and thick expansive clay layer. According to a design drawing, main and auxiliary shaft centers and periphery are determined and are marked by lime. Data including arranged circle diameters, hole number, hole spacing and the like of main drain holes, middle drain holes and rip spalling resistance holes are arranged by main and auxiliary shaft freezing holes, and drilling position is determined. In the process of carrying out freezing, the salt water temperature and the salt water cycling speed are controlled, and the frozen wall expansion speed, thickness and shaft wall temperature are controlled to achieve freezing infirmly and excavating safely. The main drain holes are used for ensuring the frozen wall to meet the requirements that circular part connection perfectly is achieved and a bedrock weathering section is frozen, and at the same time, play the roles of increasing the thickness of the frozen wall, lowering the average temperature of the frozen wall, enhancing the intensity and stability of the frozen wall with the middle drain hole collectively, and the middle drain hole also plays the role of enhancing the stability of the shaft wall under the rip spalling resistance holes. Thus, the shaft excavation speed is increased, the construction efficiency is improved significantly, the construction period is greatly shorten, the expense is saved and the economy is good.

Description

technical field [0001] The invention relates to a new technology for freezing construction of extremely thick and large expansive clay layers of shafts, in particular to a new technology for safe and rapid excavation of frozen shafts through extremely thick and large expansive clay layers. Background technique [0002] Frozen vertical shafts pass through extremely thick layers of large expansive clay, such as the main shaft and auxiliary shaft of Litang Mine in Fengxian County, Jiangsu Province. The depth of the well is -320.5~-422.0m, and the depth of the auxiliary well is -323.2~-423.8m. The thickness of the continuous clay layer reaches 101.5m and 100.6m respectively. Viscous, the natural expansion rate is 105% to 115%, the frost heaving force is 0.4 to 0.5MPa, and the frost heaving rate is 2.09% to 2.65%. The quality of freezing control is very important. Too solid freezing can guarantee construction safety, but the excavation speed is too slow and the cost will increas...

AI Technical Summary

Problems solved by technology

After the frozen wall is thawed, the well wall is stressed and the stress structure is complex

Images