In-Situ Monitoring on Frost Heave Force during Cross-Passage Construction by Ground Freezing Method

The artificial ground freezing method is widely used in the construction of cross-passage of shield tunnel. The excessive frost heave force may induce damage of the segments around the cross-passage. However, due to lack of in-situ monitoring data, no suitable frost heave force is specified in the tunnel design codes. In this paper, a careful in-situ monitoring was carried out with new PAD type earth pressure gauge in Shanghai Yangtze River Tunnel. First, the main characteristics of PAD type earth pressure gauge and the installation method were introduced. Then, the automatic data logging system and the layout of measure points were described. The careful installation ensures good working of all 5 gauges and that reliable data were obtained. The data showed that the maximum measured frost heave force of Shanghai Yangtze River Tunnel was much smaller than expected. It should be related to the countermeasure of pressure release hole, which reduced the heave pressure dramatically.