Construction Optimization Study of Double Sidewall Heading Method for Shallow Buried Oversized Variable Section Tunnel
In the construction of rail transit engineering,the double sidewall heading method is often used to construct the super-large section in the tunnel body.However,this method has some engineering problems such as difficult transformation of construction technology,difficult excavation and big security risks in the variable section tunnel,so it is urgent to be improved.This study relies on the construction of double sidewall heading method for the access section interval tunnel with 24 m wide large-span variable section in the first phase of Chongqing Rail Transit Line 24,and based on the geological structure characteristics of the tunnel site area,the optimization is carried out in the aspects of guide tunnel leading,core soil support form,temporary vertical support and temporary lateral support.Through the application of the above optimization measures,the monitoring measurement and internal force monitoring data in the process of tunnel excavation and support construction are stable and reliable,and the force system is stable,which can provide reference for the construction of double sidewall diversion with large span and variable section of similar tunnel body.
double sidewall heading methodlarge-span variable sectionthe pilot hole goes firstcore soil support formoptimization
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