Control Measures for Existing Railway Line Underpassed By Baojixia Diversion Tunnel
In order to analyze the impacts of newly constructed tunnels on the underpass of existing railway embank-ments,against the backdrop of the Baojixia Diversion Tunnel passing under the Longhai Railway,numerical simulation method was adopted,the settlement law of railway subgrade and the mechanical response of shield segment was system-atically analyzed,the law was included with formation deterioration degree,shield construction parameters,reinforce-ment measures.The results are as follows.The settlement of the railway subgrade was increased by approximately 16%,due to the deterioration coefficient of surrounding rock was reduced to 0.7.The tensile and compressive stresses within the lining was enlarged by 4%and 9%respectively.The increase in shield earth pressure and thrust contributed to the reduction of the subgrade settlement by approximately 79%and 4%,respectively.While the tensile stress in the lining was expanded by about 55%and 44%,respectively.With the increase of grouting pressure,the settlement of the subgrade was reduced by approximately 26%.With the increase of advance grouting ring thickness,the controlled settlement was reduced by 19%.The higher the type of D-type construction beam,the smaller the settlement of the railway roadbed,the lowest dropped to 2.8 mm.To ensure the operational safety of the existing railway line.To ensure the safety of existing railway lines,excessive formation disturbance and power loss of shield machine was avoided dur-ing the shield tunneling.The thickness of reinforcement ring for advance grouting was controlled within 2 m,or the ex-isting railway line was reinforced with D20 type construction beams.
万方数据
维普
