Abstract:  Data collected from the entire tunneling process of the passageway project at the portal of Zhongzhou avenue station on Zhengzhou metro line 3 are analyzed to investigate the influence of tunnel in silty or silty clay strata constructed by pipe roof and cross diaphragm(CRD) methods on settlement of surface or pipelines. Results reveal the following: (1) Tunneling by pipe roof and CRD methods can be roughly divided into six stages. The influence of pipe roofing on the surface settlement is the most significant. (2) The influence range of surface settlement caused by pipe roofing is more than three times the tunnel span, and the stratum loss rate is more than 3%. (3) Surface uplifts caused by three times of surface grouting reinforcement account for 22.43%, 28.25%, and 49.32% of the total uplift, respectively, and the surface falling back amounts after each grouting account for 19.62%, 23.03%, and 5.86% of each uplift, respectively. (4) The influence range of surface uplift caused by fullface grouting ranges from the tunnel axial line to both sides (as much as 1.6 times the tunnel span). Therefore, it is suggested that grouting should be timely synchronized behind the wall of the steel sleeve, the grouting pressure should be strictly controlled to prevent pipe blocking, the grouting rate of the upper haft crosssection should be reasonably adjusted according to surface settlement, the grouting rate of the lower haft crosssection can adopt the recommended values, the excavation face of each guide tunnel should be spaced about one times the tunnel height, and the grouting rate should not exceed 6% during the construction of strata reinforcement.

Key words: mined tunnel, silty clay stratum, pipe roof method; cross diaphragm method, grouting reinforcement, surface settlement