盾构隧道微扰动注浆对土体强度和衬砌横向收敛的影响

Influence of Perturbation Grouting of Shield Tunnel on Soil Strength and Transverse Convergence of Tunnel Linings

摘要:

软土盾构隧道横向变形直接关系到结构安全，常采用微扰动注浆方法控制。为研究隧道微扰动注浆效果，针对一段隧道双侧微扰动注浆加固后的地层，开展了静力触探试验，分析注浆对隧道周围土体的影响规律；对现场获取的土样开展了室内K₀固结不排水伸长剪切实验，获得了注浆前后土体伸长剪切强度s_u和刚度E₅₀的变化量；采用线性模型拟合注浆量和收敛值比值数据，建立了可描述相对注浆量与注浆前后收敛值比值关系的方程式，分析了注浆对收敛值降低的效果。研究结果表明，注浆使锥尖阻力提高了110.8%（注浆中心区）和97.6%（注浆边缘区），注浆加固效果呈现非均匀性；注浆后土体的s_u比注浆前提高了约112%，E₅₀提高了约132%；注浆使隧道的横向收敛累计值平均降低了约24%。利用得到的结果，可根据浆液用量对隧道横向收敛的恢复进行估算，为后续设计微扰动注浆方案治理软土盾构隧道的横向收敛提供借鉴。

Abstract:

The transverse deformation of shield tunnels in soft soils may ultimately threaten the safety of tunnel structure and is often controlled by using the perturbation grouting method. To study the effect of perturbation grouting around a tunnel， cone penetration tests were conducted to analyze the influence of grouting on the soil around two sides of a tunnel and reinforced through grouting. K0 consolidated undrained extensive shearing triaxial tests were performed on standard samples made from the soil obtained from field， and， as a result， the undrained extensive shear strength and the secant modulus were computed. A linear model was used to fit the data of grouting volume and horizontal convergence of the tunnel， and thus， an equation was built to describe the relationship between the normalized convergence value and the relative grouting volume. The effect of grouting on reducing horizontal convergence was analyzed using the built equation. The results show that perturbation grouting improves the ps by 110.8% of the soil at the grouting center and 97.6% of the soil at the edge of the grouting region， and the grouting reinforcement effect is non-uniform. In addition， the su of the soil after grouting is increased by about 112% and the E50 by about 132%. The cumulative horizontal convergence of the tunnel is reduced by about 24% after grouting measures are adopted. Using the obtained results， the recovery extent of the transverse deformation of a tunnel can be estimated according to the amount of grout， which can provide reference for subsequent design of perturbation grouting schemes to treat the transverse deformation of the soft soil shield tunnels.