Papers by Keyword: Manual Freezing Method

Abstract: With the aim of solving technical problems existing in the rehabilitation construction of butt-joint sect works with manual level freezing undermining method, under Huangpu River of Shanghai Underground Subway 4^# between Nanpu Bridge station and Pudong South Road Station, Group of large-scaled physical model tests had been performed adopting the Manual Level Freezing Undermining Method (MLFM in brief) in constructing double track tunnel. Firstly, the model design and test system integration were made; afterward, through model tests, the paper systematically studied the laws of stratum frost heaving, melting sedimentation rule and stratum displacement variations etc, during the undermining construction of tunnel being frozen. The results indicate: the Maximum displacement of frost heaving measured at the top of freezing wall during up line freezing process was 1.36mm, which is equivalent to actual work quantity of 29.92mm; the strata melting sedimentation displacement during forceful thawing is 54% less than what was during natural thawing, which illuminates that adopting forcing thawing can reduce melting sedimentation of soil blocks.

Abstract: The authors conducted research aimed at developing a new type of permeable concrete material with enhanced structural strength. This paper presents and discusses the results of their investigation on the unaxial compressive stress-strain relationship of porous concrete made with two different mix designs with constant water to cement ratio. The concrete mixes were designed with a target compressive strength between 15-25 MPa and target porosity between 10-15% to study the effect of pore sizes on the stress-strain curve. The average pore space was increased by increasing the relative amount of large aggregate. The reduction in the relative amount of fine aggregate increased the average pore space and resulted in a reduction in mix stiffness and a marginal increase in ultimate strength.