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在松软地层进行防渗工程施工时,存在钻孔易塌孔,灌浆难起压易导致垂向挤密抬动,灌浆易漏浆串浆导致耗浆量大,灌浆过程难控制等技术难题。传统的“袖阀管灌浆法”、“预埋花管法”、“孔口封闭灌浆法”等工法在深厚松软地层的施工中很难达到设计要求。为降低成本、提高工效,研究提出一种“自下而上,浆体封闭,高压脉动灌浆”新工法,介绍其中的“浆体封闭技术”成果。针对施工工艺要求,研制出低强度快凝硬塑状封孔浆体,通过实验得到性能参数;基于浆体封闭力学机理,对封孔效果进行论证,结果表明,在灌浆过程中,封孔浆体材料具备足够的止浆、耗能作用;对灌浆所需的最低注浆压力进行了计算,为选择注浆设备提供依据;另外,对自下而上灌浆施工中,提管所需的拔管力进行了计算,为提高工效、避免灌浆管出现抱死事故,提出边灌边转工艺方法,可使灌浆管顺利提升,即使在深孔情况下也无需使用拔管机。通过在怀化托口水电站河湾地块深厚松软红层进行原型试验,验证研制的封孔浆体的应用效果,分别在浅孔全段注入、深孔(最大达120 m)孔底以上20 m深注入封孔浆体材料,实施“自下而上,浆体封闭,高压脉动灌浆”。试验中8 m深松软层达到1.5 MPa以上的灌浆压力,120 m深可达到近8 MPa的灌浆压力(均为孔口压力),地层抬动仅为12 mm,灌后效果达到设计要求,表明在高压灌浆情况下,封孔浆体使用效果良好;建议在深孔注浆过程中,灌浆管边灌边转,无需使用拔管机,工艺更便捷、高效。理论研究和工程实践表明,在松软地层实施高压灌浆,采用浆体封闭技术是可行的,研制的封孔浆体性能能满足施工工艺要求。
During the seepage control construction in the soft ground, there are some technical problems such as easily collapsible holes in the borehole, difficult grouting to easily cause vertical crushing and raising, easily grouting to cause the slurry to be consumed, and difficult to control the grouting process. Traditional “sleeve valve grouting method”, “embedded pipe method”, “hole closed grouting method” and other methods in the construction of deep and soft formations is difficult to meet the design requirements. In order to reduce costs and improve work efficiency, a “bottom-up, closed, high-pressure pulsation grouting” new method was introduced and the “slurry sealing technology” was introduced. According to the requirements of construction technology, the low strength and fast setting hard plastic sealing slurry was developed, and the performance parameters were obtained through experiments. Based on the mechanical properties of the slurry, the sealing effect was demonstrated. The results showed that in the filling process, The material of the body has sufficient stopping and energy dissipation functions; the minimum grouting pressure required for grouting is calculated to provide the basis for selecting the grouting equipment; in addition, for the bottom-up grouting construction, In order to improve the work efficiency and prevent the occurrence of locking accidents, a method of edge irrigation was proposed to improve the grouting pipe smoothly without using a pipe pulling machine even in deep holes. Through the prototype test on deep, soft and red layer in Hewan block of Huokua Tuokou Hydropower Station, the application effect of the developed sealing slurry was verified. The full-thickness shallow hole was filled with full thickness of 20 m Deep injection of plugging slurry material, the implementation of “bottom-up, slurry closed, high-pressure pulsating grouting ”. In the experiment, the grouting pressure of 8 m deep soft layer reaches 1.5 MPa or more, and the grouting pressure of nearly 8 MPa can be reached at 120 m depth (both of them are orifice pressure). The lift of the formation is only 12 mm and the effect after irrigation reaches the design requirement In the case of high-pressure grouting, sealing the slurry with a good effect; proposed in the process of deep hole grouting, grouting pipe edge irrigation, without the use of tube pulling machine, the process more convenient and efficient. Theoretical research and engineering practice show that it is feasible to apply high-pressure grouting in soft ground and to use slurry sealing technology. The performance of the developed sealing slurry can meet the requirements of construction technology.