|
|
|
| Research on the Tunnel Engineering Characteristics and Construction Technology of the Tertiary Water Rich Sand |
| ZHANG Min - qing，HE Zhi - jun，XIAO Guang - zhi, REN Cheng – min |
| (China Railway Corporation，Beijing 100844, China) |
|
|
|
|
Abstract Abstract：Research purposes： When the tunnel passes through the tertiary water rich sand layer， because of high formation water content，the excavation stability is very poor，the surrounding rock deformation，collapse and flow sand are extremely serious，the construction difficulty is very large， and the security risks are high. This paper studies the dewatering measures to reduce the formation moisture content， and improve the formation stability， at the same time， takes horizontal jet grouting reinforcement stratum to improve supporting ability， or use partial excavation method to achieve the purpose of "quick dig，quick support，quick close"，to ensure the safety of the tunnel construction. Research conclusions:( 1 ) The rich water layer is a new class of special rock and soil， with the engineering characteristics of " bad water stability， poor groutability，poor uniformity and large deformation"， during tunnel construction water inrush and sand inrush disaster is extremely easy to occur， engineering difficulty and safety risk are very great. (2) The tertiary water rich sand natural water content is about 4% , the plastic limit water content is about 11%，water content of liquid limit is about 18%. After taking the dewatering measures, the formation water content can be stabilized at about 4% , so as to maintain its stability. (3) Using a combination of dewatering - segment excavation method, combination of dewatering - horizontal rotary jet grouting reinforcement method can guarantee the tunnel construction safety in the tertiary water rich sand layer. Accumulated deformation during CRD excavation is 15 ?20 cm， accumulated deformation during double column stratification method excavation for 10 ?15 cm，accumulated deformation during the excavation of double heading method for 5 ?10 cm，the accumulated deformation during the excavation of horizontal rotary jet grouting reinforcement method is 3 ?5 cm, overall, horizontal rotary jet grouting reinforcement method and double heading method are relatively safer. (4) For the rich sand water tunnel, monthly progress is 10 ? 15 m by combination of dewatering - segment excavation method, and using combination of dewatering - horizontal rotary jet grouting reinforcement method monthly schedule is 15 ?20 m. (5 ) The research results can be a reference for the design and construction for the similar tertiary water rich sand tunnel.
|
|
Received: 07 January 2016
|
|
|
|
|
|
|
2016, Vol. 33 
