模袋袖阀管压密注浆的注浆压力理论计算方法研究

针对常规注浆施工中串浆、跑浆严重,对地层加固效果不理想的现状,模袋袖阀管注浆技术开始在隧道超前注浆施工中得到应用,但目前模袋注浆压力的确定多以经验为主。考虑模袋在注浆过程中始终保持柱形扩张,同时在周围被挤密土体中形成一个由弹性区和塑性区组成的应力影响区。基于弹塑性理论,考虑在周围土体的塑性影响区内采用非关联流动法则,推导得到了表征模袋注浆过程中浆体初始半径R0、浆体现时半径Ru和土体塑性区半径Rp之间关系的表达式,由此可以解出模袋注浆压力P的理论计算公式。参数分析结果表明:模袋注浆压力值受土体弹性模量、内摩擦角、黏聚力和初始应力的影响显著。将所得的模袋注浆压力理论计算公式应用于人民会堂站的模袋袖阀管注浆工程中,由浆体扩张半径Ru随注浆压力P的变化规律可以得出:当浆液对周围土体的挤密效果最佳时,模袋注浆压力P=2.0 MPa,浆体最终扩张半径R’=20 cm。注浆效果检验结果表明:模袋注浆膨胀构造的止浆岩盘成功实现了对浆液扩散的控制,达到了预期的控域注浆效果。

Study on theoretical calculation method of grouting pressure for compaction grouting of mold bag sleeve valve tube

In view of the serious cross grouting and overflows grouting in the construction of conventional grouting technology, and the unsatisfactory effect of stratum reinforcement, the grouting technology of mold bag sleeve valve tube is often used in advance grouting construction of tunnels. But at present, the selection of mold bag grouting pressure is mostly based on experience. In this paper, it is considered that the mold bag keeps cylindrical expansion during grouting and forms a stress-affected zone consisting of elastic and plastic zones in the surrounding compacted soil. Based on the elastic-plastic theory and considering the non-correlative flow rule in the plastic influence zone of surrounding soil, the expressions of the relationship between the initial radius R0 of grouting, the radius Ru of grouting reflection and the radius Rp of plastic zone of soil during the mold bag grouting process are derived, and the theoretical formula for calculating the mold bag grouting pressure P can be derived. The results of parameter analysis show that the grouting pressure is significantly affected by the elastic modulus, internal friction angle, cohesion and initial stress of the soil. The theoretical formula of mold bag grouting pressure was applied to the grouting project of the sleeve valve tube of the People's Hall Station. From the variation rule of grouting expansion radius Ru with grouting pressure P, it can be concluded that when the grouting effect on the surrounding soil is the best, the grouting pressure of the mold bag is 2.0 MPa and the final expansion radius of the grouting body is 20 cm. The test results of grouting effect show that the sealing batholite of mold bag grouting expansion has successfully controlled the grouting diffusion, and achieves the expected effect of controlling grouting area.