Results and analysis Midas Tunnel Pile set up.rar

The Earth Pressure Balance (EPB) tunnel boring in combination of piling and sequential excavation method (SEM) is used to discuss the influence of piled tunnel lining that under crosses an existing tunnel along the Zhongshan Road. Soil investigation data and numerical simulation was applied to analyze the model. The Mohr -Coulomb (MC) model in MIDAS GTS NX software is used to simulate the settlement levels of semicircular tunnel lining and soil against various pile set ups in order to obtain the best set up for ground improvement. Results indicate a substantial variation in vertical settlement. The. designed 5x4 pile set up has the highest crown settlement but optimal lining uplift control by 138-165% while substantially increasing crown displacement by 32-47%. The 4x4 pile performs all-round by reducing uplift by 184-194 % and less volatile settlement by -12% to -47% to within 5-10mm. The 4x4 pile is more reliable and less volatile in both settlement and uplift. Uniform pile set provides a better settlement trough than non-uniform pile setups. Proposed formulas based on Gaussian function reliably uses n and k parameters to predict settlement for greenfield conditions and project behavior for tunnel under-crossings. The green field prediction function is verified using 12 existing projects and n values are estimated at prediction while back-calculation gives values close to known settlements.

本研究采用结合桩基与顺序开挖法（Sequential Excavation Method，SEM）的土压平衡（Earth Pressure Balance，EPB）盾构隧道施工方案，探讨沿中山路下穿既有隧道的桩基式隧道衬砌的影响。本次研究依托岩土勘察数据与数值模拟方法开展模型分析，采用MIDAS GTS NX软件中的莫尔-库仑（Mohr-Coulomb，MC）本构模型，模拟不同桩基布置方案下半圆形隧道衬砌与土体的沉降特性，以寻求最优的土体加固布置方案。研究结果显示竖向沉降存在显著差异。设计的5×4桩基布置方案拱顶沉降量最大，但衬砌上浮控制效果最优，控制幅度达138%~165%，不过该方案会使拱顶位移增幅达32%~47%。4×4桩基布置方案综合性能优异：其衬砌上浮控制幅度达184%~194%，沉降波动率降低12%~47%，可将沉降控制在5~10mm范围内。该方案在沉降与上浮控制方面均更可靠，且波动幅度更小。均匀桩基布置方案相较于非均匀桩基布置方案，可形成更优的沉降槽形态。本次研究提出的基于高斯函数的预测公式，通过n与k参数可可靠预测未开发场地工况下的沉降，以及隧道下穿工程的响应特性。通过12个既有工程案例对未开发场地工况的预测函数进行验证，预测过程中可估算n参数值，反演得到的参数值与实测沉降值较为吻合。