Experimental study on influencing factors of performance of equal thickness soil-cement cut-off curtain in composite strata of coal mine area

Abstract

In order to study the influence of cement content, comprehensive water-cement ratio, formation characteristics and other factors on the performance of equal thickness soil-cement cut-off curtain in coal mine, the principle analysis of equal thickness soil-cement curtain, the influencing factors of curtain performance analysis, the test and performance test of equal thickness soil-cement curtain were carried out, the key influencing factors were determined, the parameters of soil-cement of equal thickness in composite strata were obtained, and the field demonstration application was carried out. The results show that: the main factors affecting the performance of equal thickness soil-cement curtain were rock (soil) body properties, groundwater characteristics, cement cementitious materials, mixing process and curing conditions. Rock (soil) body properties and cement content were the direct factors affecting wall quality; water-cement ratio and curing period were the key factors to ensure wall quality. The ground layer had higher strength and better grain gradation, so the strength of soil-cement of equal thickness was higher and the permeability coefficient was smaller. According to the influencing factors, the cement content of the demonstration project was determined to be 25%, the comprehensive water-cement ratio was 1.2:1, and the formation was composite formation material. The treatment results of the complex formation leakage section of the gentle slope inclined shaft in Luotuoshan Coal Mine showed that the three-step construction process was used to construct the outer water cutting curtain wall of the inclined shaft with good quality. The 28 d compressive strength of the field samples was 5.3—31.8 MPa, and the permeability coefficient was 0.005×10−7—0.2403×10−7 cm/s. Wellbore water inflow decreased from 16.8 m3/h to about 1.6 m3/h, which was reduced by about 90.5% compared with before treatment.

Keywords

• cut-off curtain
• equal thickness cement soil
• composite strata
• deviated well bore
• leakage of water
• water prevention and control