富水残积土输水隧洞水平旋喷桩和超前小导管组合支护技术研究

Study on Combined Support Technology of Horizontal Jet Grouting Pile and Advanced Small Conduit for Water Conveyance Tunnel in Water-rich Residual Soil

为了研究水平旋喷桩配合超前小导管组合支护设计参数对不良地质输水隧洞预加固效果的影响,依托广西黄章水库富水残积土输水隧洞,研究了超前小导管管径、注浆加固圈厚度、外插角、环向间距、水平旋喷桩桩径、桩间距对富水残积土地层输水隧洞拱顶竖向沉降、拱腰水平变形以及掌子面变形的影响规律,并采用局部敏感性分析方法研究了支护参数的敏感性。研究结果表明:隧洞内的拱顶竖向沉降、拱腰水平收敛、掌子面位移与超前小导管和水平旋喷桩相关参数有关;小导管外插角对拱顶竖向沉降影响最大,注浆加固圈厚度次之,小导管环向间距的影响最小;小导管注浆加固圈厚度对拱腰水平位移影响最大,小导管外插角次之,小导管管径的影响最小。利用超前小导管+水平旋喷桩组合支护对富水残积土输水隧洞进行支护时,应综合考虑各参数影响,寻求最安全经济的支护参数,确保隧洞施工安全性。

To investigate the influence of the design parameters of horizontal jet grouting pile cooperating with advanced small conduit combined support on the pre-reinforcement effect of water conveyance tunnel in poor geological conditions,based on the water-rich residual soil water conveyance tunnel of the Huangzhang Reservoir in Guangxi Zhuang Autonomous Region,the influence of the diameter of the advanced small conduit,the thickness of the grouting reinforcement ring,the external angle,the circumferential spacing,the diameter of the horizontal jet grouting pile and the pile spacing on the vertical settlement of the vault,the horizontal deformation of the arch waist and the deformation of the tunnel face of the water conveyance tunnel in the water-rich residual soil strata are studied,and the sensitivity of the support parameters is studied by the local sensitivity analysis method.The results show that the vertical settlement of the vault in the tunnel,the horizontal convergence of the arch waist,and the displacement of the tunnel face are related to the relevant parameters of the advanced small conduit and the horizontal jet grouting pile.The extrapolation angle of the small conduit has the greatest influence on the vertical settlement of the vault,followed by the thickness of the grouting reinforcement ring,and the circumferential spacing of the small conduit has the least influence.The thickness of the small conduit grouting reinforcement ring has the greatest influence on the horizontal displacement of the arch waist,followed by the small conduit extrapolation angle,and the small conduit diameter has the least influence.When using the combined support of advanced small conduit+horizontal jet grouting pile to support the water-rich residual soil water conveyance tunnel,the influence of various parameters should be comprehensively considered to seek the safest and most economical support parameters to ensure the safety of tunnel construction.