松软地层高压灌浆封孔浆体研制及应用论证

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。

Development and application demonstration of stemming slurry materials for high-pressure grouting in soft stratum

For the impervious construction in soft stratum,there are various technical problems,such as easy collapse of boreholes,vertical lift induced by difficultly pressed grouting,large waste led by easy grouting leakage,and difficult grouting control.The traditional methods of "sleeve valve pipe grouting","embedded screen pipe tube" and "orifice closed grouting" are difficult to meet the design requirements in deep soft ground.To reduce cost and to improve efficiency,a new construction method,high pulsating pressure grouting from below with stemming slurry materials,is put forward,and one of the key techniques,slurry sealing technique,is described.For the construction requirements,a kind of low-intensity,rapidly solidified and hard plastic-like sealing slurry is developed,and its performance parameters are obtained.It is enough to stem grouting and to consume energy by filling slurry materials between grouting pipe and bore hole pipe wall based on the grouting mechanism.The bottom-up pulling force which provides the basis for choosing pulling machines for construction is calculated.In addition,if you turn the grouting pipe continuously during the process of grouting,the work efficiency can be improved and the grouting pipe can be smoothly promoted to avoid locking accidents even in deep borehole cases without pipe drawing machines.Through the tests on the deep soft stratum in the bay area of Tuokou Hydropower Station,the slurry materials achieve the desired effect.Theoretical study and engineering practice show that it’s feasible to adopt slurry sealing technology and to implement high-pressure grouting in soft stratum,and that the construction techniques by means of stemming slurry material can meet requirements.