Displacement Monitoring during the Excavation and Support of Deep Foundation Pit in Complex Environment

Abstract

Taking a super large deep foundation pit project as an example, the horizontal displacement of crown beam and driveway, surface settlement, axial force of anchor cable, and underground water level in the construction process of the foundation pit are dynamically monitored and analyzed. The excavation deformation rule of the deep foundation pit and the influence of excavation on surrounding buildings are analyzed. The results show that, with the excavation of the foundation pit, the crown beam and driveway of the foundation pit incline towards the direction of the pit and eventually tend to be stable. The variation of axial force of the prestressed anchor cable in the first layer of the foundation pit is basically consistent with the variation of horizontal displacement time history. The variation trend of the groundwater level at each side of the foundation pit is different but tends to be stable in a short time. In the whole monitoring period, the cumulative settlement value of each area of the foundation pit is within the controllable range, but the surface settlement of the north side of the foundation pit and a surrounding building has not reached stability, so it is suggested to extend the monitoring time of settlement in the relevant area.

Experimental Study on the Flexural Behavior of Connected Precast Concrete Square Piles

“…Te foundation pit support technologies in China mainly include cast-in place pile, prestress anchor, diaphragm wall, inner support, (composite) soil nail wall, and SMW construction method. According to incomplete data statistics, the above traditional support forms [1][2][3][4][5] are chosen by more than 95% of foundation pits. However, with the development of society and the progress of technology, the problems of high cost, large construction space, long construction period, high energy consumption, and serious environment pollution of traditional support forms have become increasingly prominent.…”

A hybrid method to determine optimal design axial forces of servo steel struts in excavations with high deformation requirements

“…Furthermore, the distances between pits and nearby sensitive buildings or structures have decreased due to the reduction in available urban spaces (Hwang and Moh, 2007;Ding et al, 2018;Beyzaei et al, 2019;Xiao et al, 2019;Wang et al, 2020). Due to the pre-stress loss in ordinary steel struts, it is difficult to control the deformation of pits with adjacent sensitive buildings or structures in soft soil areas if the retaining structures are supported by ordinary steel and concrete struts (Finno et al, 2007;Ma et al, 2008;Wang et al, 2010Wang et al, , 2012Li, 2021).…”

Monitoring and Prediction of Horizontal Displacement of Underground Enclosure Piles in Subway Foundation Pits

“…The excavation of subway station pits easily disturbs the surrounding soil and changes the soil stress field and displacement field, which is very likely to cause secondary disasters such as underground pipe network damage, surface building tilt, cracks, and even collapse. − At present, the popular precautions and regulations to reduce disaster risk are increasing the underground enclosure piles during excavation, which would reduce the deformation of surrounding strata and impact on surface buildings . Therefore, carrying out stability monitoring and dynamic risk warning of underground enclosure piles is a key issue to ensure the safety of foundation pits, guarantee the implementation of underground space engineering, and achieve rapid urban development …”

“…9 Therefore, carrying out stability monitoring and dynamic risk warning of underground enclosure piles is a key issue to ensure the safety of foundation pits, guarantee the implementation of underground space engineering, and achieve rapid urban development. 10 Both domestic and international scholars have unveiled the deformation law of the foundation pit. In the 1940s, Peck and Terzaghil established the total stress calculation method for predicting slope stability and internal support load magnitude.…”