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| Field test of static pressure pile group based on high precision automatic monitoring system |
| WEI Limin，DU Meng，HE Qun，LIAO Pengqing，LI Shuanglong |
| (School of Civil Engineering，Central South University，Changsha，Hunan 410075，China) |
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Abstract The squeezing effect of prestressed high-strength concrete pipe piles is one of the most concerned issues in geotechnical engineering. Based on the connection-subgrade project of Qufudong station in Lunan High-speed Railway，a field test of jacked pile group was carried out on the east side of the newly railway line. A high precision automatic monitoring system was established to all-weather monitor the development of the surface horizontal and vertical displacement，deep horizontal displacement，excess pore water pressure and groundwater level caused by soil compaction effect of jacked pile group with high frequency. The test results in area IV and VI，and control effect of the pre-drilled hole and isolation effect of the front piles were analyzed. Results show that：(1) Taking 1.5 mm as the boundary value，the influence range of surface horizontal displacement of jacked pile group in area IV and VI are 50.0 m and 37.0 m，respectively；(2) The squeezing effect of the rear piles can be effectively isolated by the first 5–8 rows of piles；(3) The squeezing effect can be effectively reduced by pre-drilled hole. Taking the measurement point of 5 m from the test area boundary as an example，the maximum horizontal displacement in the test area with pre-drilled holes of 20 m is 74% of that with pre-drilled holes of 15 m，and the maximum horizontal displacement in the test area with pre-drilled holes of 15 m is 25.8% of that of without pre-drilled hole under the same reinforcement width.
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2020, Vol. 39 
