ground settlement
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Geosciences ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 41
Author(s):  
Md Shariful Islam ◽  
Magued Iskander

A parametric study that examines the ground surface settlement due to the excavation of shallow offset arrangement twin tunnels is presented. Offset arrangement tunnels are those that run parallel to each other, but at different elevations. The study focuses on the influence of both the construction sequence and various geometric parameters on the induced soil settlement. A series of three-dimensional finite element analyses was carried out to investigate the settlement behavior and interactions between offset arrangement twin tunnels excavated in clay using a simplified mechanized excavation method. Analyses were carried out for three cover-to-diameter (C/D) ratios, three possible construction sequences, five angular relative positions, and five angular spacings. In addition, settlement data were also investigated by varying horizontal and vertical spacings while keeping the angular spacing constant. The total settlement of the excavated twin tunnels and the settlement induced solely by the new second tunnel are both presented, and special attention was paid to identifying the dominant geometric parameters. The observed data trends from this study are generally consistent with the limited data available in the literature. This study confirmed a few perceived behaviors. First, angular relative position better describes the settlement behavior in comparison to angular spacing. Second, the effect of the vertical distance is noticeably more significant than that of the horizontal distance between the two tunnels. Third, excavation of the lower tunnel at first induces higher total ground settlement than when the upper tunnel is excavated first or when both tunnels are excavated concurrently. Fourth, settlement due to the construction of the newer tunnel decreases with the increase in the cover depth. In addition, two design charts have been proposed to calculate the settlement induced from a new second tunnel excavation and the eccentricity of the maximum total settlement relative to the center of the new tunnel.


2022 ◽  
Vol 2022 ◽  
pp. 1-11
Author(s):  
Xuepeng Zhang ◽  
Yujing Jiang ◽  
Yue Cai ◽  
Xin Li ◽  
Naser Golsanami ◽  
...  

Stochastic medium (SM) theory is a practical method in ground settlement prediction, while its nonintegrable double integral form makes the solution process complicated. A simplified analytical solution based on the SM theory is developed to predict the ground movement in tunneling excavation. With the simplified solution, the ground movement for single tunnel and twin tunnels could be predicted based on the gap parameter G and influence angle β. A feasible approach is developed to estimate these two parameters using the maximum ground settlement Smax and tunnel design parameters, including tunnel depth H and diameter R. The proposed approach can be used to predict the ground movement curve for both circular and noncircular cross section tunnels. To validate its accuracy, the results predicted by the simplified procedure are compared with those obtained by the SM theory and measured in situ. The comparisons show that the current results agree well with those obtained by the SM theory and measured in situ. The comparison of five tunnels in literature illustrates that the simplified method can provide a more reasonable prediction for the ground movement induced by tunneling.


2021 ◽  
Vol 12 (1) ◽  
pp. 129
Author(s):  
Weizheng Liu ◽  
Tianxiong Li ◽  
Jiale Wan

A complete case record of a deep foundation pit with pile-anchor retaining structure excavated in red sandstone stratum is presented in this study. The horizontal displacement of pile top, the horizontal displacement at various depths, the axial force of anchor cable, and ground settlement during construction are measured. A three-dimensional numerical model is established to analyze the additional stress and deformation induced by the excavation and the accuracy of the FEM model is verified by comparing with field measured results. Both the measured and numerical simulation results show that the deformation of the pile-anchor supported deep excavation is significantly affected by the spatial effect. The results show that the deformation in the middle of the foundation pit is greater than the pit angle and that the deformation of the long side is greater than that of the short side and gradually decreases from the middle to the pit angle. The deformation and stress in the middle of the long side of the foundation pit are the largest, which is the most unfavorable part. With the increase of vertical excavation depth, the spatial effects tend to increase, and the influence scope of spatial effects is about five times the vertical excavation depth in the red sandstone stratum. The ground settlement outside the pit is mainly distributed in a groove shape, and the maximum settlement occurs about 8.5 m away from the pit edge. Finally, parametric studies of reinforcement parameters indicated that 1.5–2.0 times the initial elastic modulus and cohesive force of soil should be used for reinforcement. It is recommended that the ranges for pile diameter, pile spacing, anchor cable prestressing and inclination angle should be selected as 0.8–1.2 m, 1.4–2.0 m, 100–150 kN, and 10°–20°, respectively.


2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Nhat Luan VO ◽  
Thi Nu NGUYEN ◽  
Minh Toan DO

Urban metro line No. 2 from An Suong station to Thu Thiem is one of the six metro lines thatis planned to be built in Ho Chi Minh City (HCMC). The metro line goes through the area in which thestratigraphy consists of many units, distributed from 20-80 m. The hydrogeology mainly has 2 aquifers,namely Holocene, and Pleistocene which affecting the deep excavation. During construction, there willbe some problems that will affect the work on the surface such as settlement, cracking, and damage. Byfinite element method on Plaxis software, the article forecasts the surface settlement during this metroline No.2. The results show that the ground settlement is relatively large in areas with soft groundstructures. The settlement results depend on the geological structure characteristics, hydrogeologicalcharacteristics, and the shape and size of the tunnels.


UKaRsT ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 252
Author(s):  
Wellyanto Wijaya ◽  
Paulus Pramono Rahardjo ◽  
Aswin Lim

Cisumdawu Tunnel is a twin tunnel 472 m long located in Sumedang. Twin tunnel construction can cause additional ground settlement and tunnel deformation. The tunnel construction method used is the New Austrian Tunneling Method (NATM) and umbrella grouting protection system. The principle of NATM is to maximize surrounding soil capacity to support its weight and balance the stresses around the tunnel. Investigation of tunnel deformation is important to know tunnel structure behavior and avoid possible failure. This research aims to know tunnel deformation and the effect of twin tunnel construction on the deformation and ground settlement. The data used such as tunnel geometry, monitoring data, pressuremeter test, and the drilling test. The 3D analysis will be performed for a single tunnel and twin tunnel using Midas GTS-NX, and monitoring data will be used for verification analysis. The 3D FEM help to model the soil condition and construction stage according to the actual condition. The analysis results show the maximum tunnel deformation that occurs from the beginning of the tunnel construction is 12.64cm. If the deformation starts to be calculated following the monitoring reading time, after the excavation at the monitoring point, the maximum deformation of the analysis results is 3.3&4.4cm, where the monitoring shows maximum deformation of 3.3&4.3cm. Through the results, it can be said that the analysis using 3D FEM with pressuremeter test parameter represents actual conditions. Twin tunnel construction side-by-side increases ground settlement and lateral tunnel deformation significantly. Hence, it shows that tunnel analysis using 3D FEM recommends for future investigation of tunnel deformation.


2021 ◽  
Vol 13 (24) ◽  
pp. 13696
Author(s):  
Uiseok Kim ◽  
Byungchan Min ◽  
Junghoon Kim ◽  
Hangseok Choi ◽  
Sangwoo Park

The development of underground spaces in urban areas plays a crucial role in the regeneration and sustainability of cities. However, the conventional underground excavation works in metropolises limit the use of the ground facilities owing to stability, noise, and vibration problems, which may cause huge economic damage. In this study, a method of pre-constructing slabs of underground facilities was analyzed to improve the stability of the floating and underground extension method, even during the use of the target building. First, a numerical simulation was conducted to compare the stability of the top-down method with slab pre-construction with that of the conventional top-down method. Then, the stability of the test bed was checked by applying this construction method to the field. As a result, the top-down method with slab pre-construction significantly improved the stability of the target building by preventing the buckling of the columns and supporting members. The increase in the displacement of existing columns and supporting members was controlled after the pre-construction of the slab. In addition, the crack width and ground settlement were stable within the management standards at the field. Thus, this construction method is expected to be crucial in pursuing urban regeneration and sustainability through the efficient development of underground spaces.


2021 ◽  
pp. 327-341
Author(s):  
Chiranjib Sarkar ◽  
Sibapriya Mukherjee ◽  
N. Kumar Pitchumani

2021 ◽  
Author(s):  
Fei Wang ◽  
Songxian Huang ◽  
Wen Chen

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.


2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Jun Tang ◽  
Shengcai Li ◽  
Yongfu Zhu

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.


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