Long-Distance Pipe Jacking in Complex Urban Geological Environment

A steel underground pipeline with a diameter of 2.4 m and a total length of 3,617 m (plate thickness of 26 mm) has been constructed in a city in central Hubei, and the engineering, procurement, and construction (EPC) project has been lifted from the upstream channel to supplement water to the downstream lake inside the city. Through preliminary geological survey data, site topographic and geomorphic survey, urban construction, as well as the requirements of the construction party, the preliminary arrangement of working wells and receiving wells as well as the selection and customization of pipe jacking machines have been proposed. Frequency conversion motor and remote monitoring technology are adopted for geotechnical change and long-distance pipe jacking. Through detailed survey, the rock and soil change section as well as gradual change conditions have been determined, the accuracy of construction mechanics calculation and construction operation control have improved, the basis and analysis basis are provided, and some experiences in construction operation are summarized.

The Numerical Analysis of Tunnel Traversing Piles and Its Seismic Response in Deep Soft Soil

The Ou River estuary deposits deep soft silt and silt clay, the pipe-jacking tunnel departures from Qidu island, then passes underneath north levee road, viewing platform, Ou River and Ou River road, finally reaches the received well. The net distance between tunnel segment and the viewing platform piles is only 230mm. In order to analyze the negative influence of large diameter pipe-jacking tunnel traversing piles of viewing platform, the numerical model is established, and the levee road settlement value is found which matches with observed settlement very well. The dynamic analysis is also conducted by EI Centro seismic wave, and the result reveals that the max displacement occurs on the segment between the rear row piles of viewing platform, and the max displacement reaches 68.6mm in the earthquake.

Analysis on Surrounding Environment Influence Induced by Rectangular Pipe Jacking and the Control Scheme

Based on rectangular pipe jacking project of the No.1 entrance of Qingshi Road station on Wuxi metro Line 4, to analysis how different treating methods work in the aspect of vertical deformation of the pile foundation around the pipe jacking tunnel and the ground settlement during pipe-jacking construction process, a 3-D finite element simulation model which simulate the process of rectangular pipe jacking crossing under viaduct is established. Some conclusions is drawn as follow: (1) the combination of isolation piles and shallow soils grouting reinforcements can constrain the vertical and horizontal deformation of the pile foundation and ground settlement caused by rectangular pipe jacking. (2) Both the maximum ground settlement and maximum ground heave can meet the requirement of special monitoring. (3) The result of the simulation is basically consistent with on-site monitoring data, which can prove the availability of the simulation and the treatment scheme.

Measurement and Analysis of Settlement Induced by Rectangular Pipe Jacking in Silt Stratum

The large-scale rectangular pipe jacking technology has attracted more and more attention in the construction of urban underground pipe galleries, especially the problem of prediction and control of the surface settlement. Taking the pipe gallery project of Chengbei Road in Suzhou as an example, the settlement values of three groups of monitoring sections under the conditions of natural settlement and synchronous grouting are monitored, and the measured settlement values are compared with Peck formula and random medium theory. The results show that the Peck formula is more accurate in predicting the natural settlement within 1.5 times the pipe jacking width, while the stochastic medium theory is more accurate in predicting the settlement beyond the width. By comparing the field test and theory, the suggestions on the prediction of ground settlement of rectangular pipe jacking of large scale are put forward. The results of this study provide a basis for subsequent related research work and engineering applications.