盾构隧道渗漏灾害中堵漏浆材作用机制试验研究

Experimental Study on Leakage Sealing Mechanism of Slurry in Shield Tunnels

注浆堵漏常用于盾构隧道渗漏事故的抢险过程中,合理的注浆能够有效封堵渗漏点,避免险情进一步恶化。为研究不同地层中隧道渗漏后不同堵漏材料的作用机制,基于不同地层侵蚀状态下盾构隧道发生渗漏险情后的发展特征,提出渗流型和空洞型2种渗漏事故类型;进一步考虑注浆材料物理化学性质的差异,将堵漏浆材划分为膨胀型和黏结型2种不同类型,从而通过模型试验研究不同类型浆液在不同渗漏事故类型中的作用机制。研究表明:1)注浆封堵的机制是浆液固化物通过膨胀性或者黏结性在接触面上形成较强的正应力,当接触面正应力超过水压力时,外部流水无法进入隧道内部,堵漏成功;2)渗流型地层中浆液扩散距离主要受到浆液凝结时间、地层渗透系数、浆液黏度、注浆压力、水力梯度等因素的影响,并通过试验给出浆液扩散距离的经验公式;3)渗流型地层中,油性聚氨酯反应生成固化物膨胀挤压周边地层,通过挤压力抵抗外水压力,水性聚氨酯的接触面挤压力小于油性聚氨酯,通过包水性消耗孔隙水,同时结合挤压力实现堵漏;4)空洞型地层中,油性聚氨酯固化物以自密封的形式、水性聚氨酯以黏结力和自密封共同作用的形式实现堵漏效果;5)空洞型地层中,堵漏注浆的浆液扩散过程受浆液及其生成物密度的影响,针对不同渗漏位置需要选用不同的浆液类型。

Grouting is commonly used in shield tunnels to stop water and sand inrushes by effectively sealing leakage points to prevent their further deterioration.To investigate the mechanism of different sealing materials for tunnel leakage in various strata,leakage accidents are divided into"seepage type"and"cave type"based on the deterioration characteristics of shield tunnels under various erosion stages of strata.Furthermore,the sealing grout is divided into"expansion type"and"bonding type"according to the chemical properties of the grouting materials.The working mechanisms of different types of slurries for various leakage issues are investigated through modeling tests.Results reveal the following.(1)The consolidated material exerts high positive stress on the contact surface through expansion or adhesion.When this positive stress on the contact surface exceeds the water pressure,the external flow of water cannot enter the tunnel,thereby stopping the leakage.(2)In the seepage-type strata,the spreading distance of slurry is primarily affected by the condensation time of slurry,permeability coefficient of strata,viscosity of slurry,grouting pressure,and hydraulic gradient.The empirical formula for the spreading distance of the slurry is given by tests.(3)In the seepage-type strata,the expansion of oil-based polyurethane generates a large positive stress that resists the external water pressure.The pressure on the contact surface of waterborne polyurethane is lower than that on oil-based polyurethane.This is because waterborne polyurethane consumes pore water and achieves leakage sealing under expansion pressure.(4)In the cave-type strata,oil-based polyurethane stops leakage by self-sealing,while waterborne polyurethane stops leakage by the combined action of adhesion and self-sealing.(5)In the cave-type strata,slurry diffusion is affected by the density of the slurry and its products.Further,appropriate slurries should be selected based on leakage locations.