Influence of differential frictional resistance around rectangular pipe jacking on longitudinal horizontal displacement of strata

Abstract

In the process of rectangular box jacking, the friction resistance around the pipe is an important factor that causes the disturbance of the surrounding soil. To predict the influence of rectangular pipe jacking construction on stratum displacement more accurately, the calculation formula of horizontal displacement of soil is established based on the Mindlin solution of elastic mechanics, assuming the state of 'U' shaped mud sleeve combined with the stress analysis of pipe joint and the law of mud movement, and the vertical-horizontal displacement of stratum caused by additional stress on the front and friction resistance around the pipe is calculated. Finally, it is compared with the measured values of a rectangular box jacking project in Suzhou. The results show that before the pipe jacking head passes through a certain fracture, the effect of the additional stress on the surrounding soil is greater than the differential friction resistance around the pipe.However, after crossing the section, the cumulative effect of the latter is gradually greater than the former due to the increase inthe number of pipe segments and the "pull" effect of the friction resistance around the pipe jacking that haspassed through. The calculated value in the case of differential friction resistance is closer to the measured value than that in the case of uniform friction resistance, and the prediction effect is better.

Keywords

• rectangular pipe jacking
• pipe soil contact interface
• differential frictional resistance around pipe jacking
• mindlin solution
• longitudinal horizontal displacement of strata