Ground Response to Tunnel Construction for Jakarta MRT

Started: January 2016
Supervisor: Standing, J.R.
Funding: Indonesia Endowment Fund for Education

Background

One of the important issues in urban areas in developing countries is transportation. Jakarta, for instance, a province with a total population of over 10 million and 13 million during the day, has congested transport networks. In order to reduce congestion on major roads, there is an increasing demand for sustainable transportation because of the wide extensive growth of the capital city which therefore necessitates an increase number in underground infrastructure. The Jakarta Mass Rapid Transit (MRT) has been proposed to relieve traffic on some of the major congested roads. This project consists of two corridors, namely a 25km north to south (NS) corridor with 21 stations and an 87km east to west (EW) corridor with 87 stations. The NS corridor, connecting Lebak Bulus in the south to Jakarta Kota in the north, has been divided into two phases which are a 15km NS Line 1 and a 10km NS Line 2. In general, the NS Line 1 consists of two types of structure: an elevated section from Lebak Bulus to Sisingamangaraja Station, and underground structures from a transition zone immediately north of Sisingamangaraja Station to Bundaran Hotel Indonesia (HI). One part of the NS Line 1 project involves tunnelling beneath major roads in the centre of Jakarta. The northbound and southbound tunnels of the NS Line 1 have a total length of 4 km excavated by earth-pressure-balance machines (EPBMs) with an outer diameter of 6.65 m. The entire length of the tunnel alignment, based on the geological map for Jakarta (Turkandi, et.al. 1992), is within superficial deposits which typically comprise alluvial fan deposits (Qav) of beds of fine tuff and sandy tuff interbedded with conglomerate tuff, underlying alluvial deposits (Qa) of clay, silt, gravel, cobbles and boulders. Nine stratigraphic units were identified during geological studies on the site for which an extensive set of boreholes were drilled. According to these studies, the tunnel alignment is mostly located in soft to firm alluvial clay overlying stiff to hard alluvial, and dilluvial clay.

The tunnel alignment passes close to multi-storey buildings and beneath major bridges. Tunnelling-induced ground movements along the major roads with high-rise buildings and other important structures such as bridges are of substantial concern. It is necessary to prepare a prognosis of ground behaviour for instance vertical and horizontal displacements during excavation to control and limit damage to existing buildings or other structures (e.g. bridges, a 2m water main, and river walls) near to the new tunnels. Standing & Burland, (2006) stated there are three primary quantities that control the settlement and its extent, namely depth to the tunnel axis z, trough width parameter K, and volume loss VL.

In practice, empirical methods are commonly used to predict surface settlement profiles which can be expressed and idealized by a Gaussian distribution curve (Peck, 1969; O’Reilly and New 1982). In order to determine horizontal displacement profiles, Attewell, et al. 1986 suggested using a point sink assumption, which results in the derived maximum horizontal displacement occurring at the point of inflection. Some researchers have attempted to relate maximum surface settlement (wmax) to maximum settlement at the crown (wc), i.e. sub-surface movements (Cording et al. 1976; Clough & Schmidt, 1981; Ward & Pender, 1981). Sub-surface vertical displacements are generally well predicted using the approach suggested by Mair, et al., 1993.

Many empirical methods for predicting tunnelling-induced ground movements have been developed but most of them apply to greenfield conditions. A key input is the volume loss which is dependent on several factors. Large differences in volume loss were recorded during the construction of the Jubilee Line Extension (JLE) in the vicinity of Westminster. Standing and Burland (2006) observed that the maximum vertical settlement in the transverse direction of the westbound JLE tunnel was 20.4 mm and the volume loss VL of this profile was 3.3%. This measured VL was much larger than the value used in the design, for which a volume loss of 2% was adopted. Their studies revealed that the method of tunnelling and construction control, and the geological conditions made a significant contribution to the large volume losses recorded. These findings could be equally applicable to sub-surface infrastructure projects such as the Jakarta MRT.

This research project focuses on tunnelling-induced ground movements and monitoring of the ground and structures along the route of the Jakarta MRT construction.

The main objectives of this research can be described as follows.

  1. Analysing geology and ground condition along the alignment of the Jakarta project.
  2. Understanding mechanisms of tunnelling–induced ground movement in the short and long term.
  3. Analysing the construction methods and the control of ground movements.
  4. Predicting short- and long-term ground movements implementing empirical models.
  5. Collecting and analysing monitoring data of horizontal and vertical ground displacements close the structures, e.g. high-rise buildings and bridges.
  6. Comparing predicted and actual ground movement profiles.
  7. Analysing and determining factors influencing volume loss.
  8. Performing back-analyse for the determination of representative ground parameters.

References:

  1. Standing, J.R. and Burland J.B. (2006). Unexpected tunnelling volume losses in the Westminster area, London. Geotechnique 56, No. 1, 11–26.
  2. Mair, R.J., Taylor, R.N. & Bracegirdle, A. (1993). Subsurface settlement profiles above tunnels in clay. Geotechnique 43, No. 2, 315–320, http://dx.doi.org/10.1680/geot.1993.43.2.315.
  3. Turkandi, T., Sidarto, Agustyanto, D.A. & Hadiwidjoyo, M.M.P. (1992). Geological map of Jakarta and Kepulauan Seribu Quadrangles, Jawa. Quadrangle: 1209-4 &1210-1. Scale: 1:100,000. Geological Research Centre.
  4. Attewell, P.B., Yeates, J. & Selby, A.R. (1986). Soil movements induced by tunnelling and their effects on pipelines and structures, Blackie Glasgow.
  5. O'Reilly, M.P. and New, B.M. (1982). Settlements above tunnels in the United Kingdom - their magnitude and prediction. In: Proceedings of Tunnelling 82, Brighton. 173-181.
  6. Clough, G.W. & Schmidt, B. (1981). Design and performance of excavations and tunnels in soft clay. In: E.W. Brand & R.P. Brenner, (eds), Soft Clay Engineering. Elsevier Scientific Publication Company, Amsterdam, Chapter 8.
  7. Ward, W.H. & Pender, M.J. (1981). Tunnelling in soft ground - General Report. In: Proceedings of the 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 4, 261-276.
  8. Cording, E. J. & Hansmire, W.H. (1975). Displacements around soft ground tunnels. In: Proceedings of the 5th Pan American Conference on Soil Mechanics and Foundation Engineering, Buenos Aires, 4, 571-633.
  9. Peck, R.B. (1969). Deep Excavations and Tunnelling in Soft Ground (State of the Art Report). In: Pro. VIIth ICSMFE, Mexico, vol. 7 (3), pp. 225–290.

HOANG NGUYEN

Hendarto HendartoPhD Candidate - Geotechnics 
Department of Civil & Environmental Engineering 
Imperial College London SW7 2AZ 
h.hendarto15@imperial.ac.uk