隧道白云岩砂化段帷幕注浆处理技术

Curtain Grouting Technique in Dolomite Sandification Zone in Tunnel

为研究隧道白云岩砂化段帷幕注浆处理技术,通过计算、数值模拟和工程实践方法研究了处理技术的四种关键影响因子,即注浆压力、注浆材料、注浆厚度和注浆工艺。结果表明:在全强砂化白云岩粉细砂层中帷幕注浆应采用高压劈裂注浆,注浆终压建议为4~5 MPa;通过数值模拟确定双液浆最适合白云岩砂化段注浆处理工程;经过公式计算和数值模拟对比,注浆厚度公式可采用经验公式计算,方便简单,一般地层中可取开挖半径值;注浆顺序原则为:由外到内、由下到上、间隔跳孔,分三序孔施工;前进式注浆工艺能够较好地解决成孔质量问题,但应结合现场条件合理调整分段长度,白云岩砂化段分段长度以0.5~1 m为宜;注浆过程中可以先进行双液浆灌注形成维护圈,再进行超细水泥的局部补强。可见,这些成果可为类似隧道帷幕注浆工程提供借鉴,保障安全掘进和工程质量。

To study the curtain grouting treatment technology of sand-filled dolomite section in tunnel. Calculation, numerical simulation, and engineering practice were conducted to investigate four key influencing factors of treatment technique, namely, grouting pressure, material selection, grouting thickness, and grouting process. Results show that high-pressure splitting grouting should be used in the filling cavity of dolomite sanded section silt fine sand, and the final grouting pressure should be 4~5 MPa. Using the ANSYS modeling analysis, it is concluded that the double liquid slurry is the most suitable for the curtain grouting project of the sand-filled dolomite. The grouting thickness formula can be calculated by empirical formula, which is convenient and simple, and the excavation radius value can be obtained. The grouting is carried out from outside to inside, from bottom to top, and interval drilling. The progressive grouting technology can better solve the problem of hole-forming quality, but the length of segments should be adjusted reasonably according to the site conditions. The progressive sectional grouting technology is adopted for dolomite sanding section, and the length of segments is 0.5~1 m. In specific projects, double grouting should be performed first to form a maintenance circle, and local reinforcement with superfine cement is carried out. The results provide a reference for similar grouting project in tunnel.