This collection of reviewed papers covers a wide range of tunnelling practice, from deep excavations in Singapore to the construction of a new metro line in Barcelona. The international scope of the contributors makes this a truly comprehensive collection of work on the geotechnical aspects of soft ground excavation. Amsterdam, the Netherlands, June The effects of tunnelling on existing structures. Mitigating measures for underground construction in soft ground. Deep excavations. Threedimensional numerical simulation of tunnelling effects on an existing pile.
Settlement behaviour of a shield tunnel constructed in subsiding reclaimed area. Influences of physical grout flow around bored tunnels. Centrifuge experiments on stability of tunnel face in sandy ground. Geotechnical centrifuge tests to verify the longterm behaviour of a bored tunnel. Analytical stability models for tunnels in soil. Then, the ground above and between the shield tunnels is excavated from its surface after the tunnel has been installed with internal supports to prevent defor- mation of the segment due to the excavation.
The top slab, bottom slab and center wall are constructed while the ground between the tunnels is being excavated.
Finally, the parts of the steel segments are removed. In this procedure, since the excavation with the shield machine still continues after it passed by the section, as seen in Step 1, the work of cut-and- cover excavation with cutting the steel segments as seen in Steps 2 to 6 is carried out simultaneously with segment supply and other works. Currently, further development of the shield enlargement method by trenchless method has been developed, since the depth of enlargement section is very deep and there exist many structures on the ground.
The cross section of the enlarged portion is shown in Figure From various trenchless methods, the mountain tunneling method is employed for enlargement of the shield tunnels for this site because the ground with high self-sustainability where the shields are located is composed of Neogene Pliocene. Construction procedure for the ramp and junction section.
It is confirmed that the entire area of the face and above the face of the ground are an elastic state through all the construction steps. And safety factor Fs for collapses of the surrounding ground after completion of lower half excavation is cal- culated by Mohr-Coulomb yield criterion. It is verified that Fs of entire area surrounding ground and the center pillar are 1. Therefore, it is determined that the ground improvement is not necessary. However, the exploration to check the cavity and significant loosening of the ground between two tunnels from the inside of the shield tunnel is carried out since the center pillar is very impor- tant to secure the stability of entire tunnel during enlargement.
The results of measurements such as displacement of the ground, the stress of steel arch support, sprayed mortar and steel segment are less than design and calculated values. For the projects such as road and railway, deep underground space is expected to be more utilized in the future since effective utilization of urban space and reducing environmental impact will be required.
Those projects may need tunnel construction into the unconsolidated ground under high water pressure so that it is required to develop further advancement of shield tunneling technology and the lining design. In addition, the innovative shield tunnel enlarge- ment method will be more employed for the con- struction of merging and diverging section with the trenchless method.
In order to achieve the construction described above, further study on load such as earth pressure,. The tunnel covering this segment will be three lanes on each side and the largest shield road tunnel in Japan. As a contacting facility, it has been planned to build Oizumi junction, Chuo junction and Tomei junction, connecting with Kan-Etsu Expressway, Chuo Expressway, and Tomei Expressway respec- tively.
In addition, it has been planned to build Mejiro-Dori avenue interchange connecting with Mejiro-Dori avenue, Tohachi-Doro avenue inter- change connecting with Tohachi-Doro avenue and Ome-Kaido avenue interchange connecting with. Overall plan and the arterial highway. Ome-Kaido avenue. In the Law on Special Measures related to Public Use of Deep Underground, it is possible to set usage rights for Deep Underground projects with- out prior compensation for public interest projects of roads, rivers, railway, telecommunications, elec- tricity, gas, water, sewerage and other lifelines that are closely related to daily life.
The construction project is the second applica- tion case in Japan and the first case as roads based on Law on Special Measures related to Public Use of Deep Underground. East Nippon Expressway Co. Central Nippon Expressway Co. Each company ordered two shield machines. One starts from Oizumi junction and the other from Tomei junction. Now, the shield machines are. The soil stratum along the shield tunnel pre- sented in Figure 17 is very hard as Kazusa-So- Gun soft rock. From Tomei junction to Oizumi junction, the cohesive soil layer Kita Tama layer , sand layer Higashi Kurume layer and alternation of strata containing pebble, sand and cohesive soil.
Considering the construction requirements of the tunnel and the expectation for early operation, the social adverse impact will be large if the risk becomes obvious. Therefore, in order to achieve this safety, the start of tunnel boring from two portal sides are adopted Tomei junction and Oizumi junction. In addition, in the case of unforeseen trouble during tunneling,. The water permeability of ground around the enlargement of underground at Chuo junction and Ome-Kaido avenue interchange is higher than at Tomei junction.
Because there is the enlargement of underground at Chuo junction and Ome-Kaido avenue interchange under the low autonomy ground, it is required to work more technical and difficult construction.
Bloggat om Geotechnical Aspects of Underground Const...
Therefore, the construc- tion method will be decided after discussing and inspecting the technical issue further. Deep underground according to the Law. JR-Sobu Line is an important Railway for Tokyo metropolitan area, so a stop of the com- mercial line due to construction and allowing down of the driving speed are impossible. Fur- ther, the road shape constraints, it is not possible to deepen the depth of the road structures.
In order to build a.
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Geologic map along the route. Longitudinal cross section of main shield tunnel and diversions. However, for the renovation of the viaduct, it is necessary to construct it in the night, when a train operation has ended. There- fore, the construction cost and the necessary time period increase.
In this project, to do the under- pinning the existing viaduct and to renovate the long span viaduct, the new box culvert is con- structed within the ground. A completion image is shown in Figure A four-lane Expressway at an underground part and a three-lane ordinary road above a ground part are planned to be constructed in the section.
An underground structure is box culverts of 1 layer and 3 spans. Figure 20 shows the geological features at the construction site. The top 1. Underlying fills are an alluvial sand layer of 4. The groundwater level is around G. Figure 21 presents an overview of the con- struction. The summarized construction steps are listed:. Step large-scale box culverts After that, existing pillars were cut and removed Figure 23 ; and Step after the replacement of the load of via- ducts, we built a box culvert in the central part by inverted lining method.
Subse- quently, 3 box culverts were connected and the tunnel structure was completed Figures 24 and Step connecting the three boxes. The completed structure. The Chuo Shinkansen is planned to be built as a new line between Tokyo and Osaka by maglev linear. It is opening the train track lines between Tokyo and Osaka in There are 2 reasons for the construction of Chuo Shinkansen.
The first is that the substitution line of Tokaido Shinkansen is needed, which passes an expected disaster area of the Nankai Trough massive earthquake. The second is that Tokaido Shinkansen needs the reconstruction with a long suspension. A characteristic of a Chuo Shinkansen is using a run system of maglev linear, and for a special quality, a run route is to pass through Southern Alps Mountains earth covering m, length of 25 km approximately of mountain tunnel as straight as possible, also it uses the deep under- ground basically at Tokyo area and Aichi area.
Route longitudinal view between Tokyo and Nagoya is shown in Figure Chuo Shinkansen with the extension of km and the tunnel part of km, includes the long mountain tunnel and the deep underground shield tunnel. Urban tunnel of the Chuo Shinkansen is in the Tokyo area that leads to the left bank of Sagamihara, Kanagawa from Shinagawa terminal station and in the Aichi area that leads to the terminal station of Nagoya from Aichi interval. The Urban tunnel is planned to be constructed mainly by the shield TBM methods, except terminal station and the underground station in Kanagawa.
Soft ground focus for geotechnical symposium
Based on the special law mentioned in the Gaikan project, it is characterized in that passing through the underground 40 m deeper except for around the station unit. That structure is expected to be the starting and the arrival shaft for the shield tunnel construction. Standard sectional view of the shield tunnel is shown in Figure On the other hand, inside the emergency exit, placing the ventilation facilities for performing ventilation in the tunnel.
In the ventilation facili- ties, placing a porous plate as a countermeasure to the micro-pressure waves and low-frequency sound, in addition to the ventilation equipment and the sound reduction equipment. Also, placing the opening and closing facili- ties for wind pressure measures at the time of the train pass, and installing a refuge for the elevator and the stairs of the abnormality, and placing the elevator and stairs for the evacuation of the emer- gency.
Overview of this emergency exit is shown in Figure Many of the mountain tunnels are planned to penetrate the steep mountains with a deeply carved valley. In the Southern Alps and the Central Alps Moun- tains, the extension length is planned to be more than 20 km. Standard sectional view of the shield tunnel. Standard sectional view of a mountain tunnel is shown in Figure Southern Alps tunnel is planned to be an exten- sion of about 25 km. Geology is a Shimanto layer group and the Chichibu raw layer made of the sandstone and slate. The mechanical nature of the steep mountain is difficult to detect directly.
Therefore, it is planned to drill a pilot tunnel that precedes the main pit. During the construction, the high-pressure spring water around the fracture zone and the rock extrusion by a huge rock stress are expected to be faced. This connecting line will be used for through line operation that alternates between the Sotetsu line and the JR line.
The construction project was approved in October Almost all of the 2. This connecting line will be used for through line operation that alternates between the Sotetsu line and the Tokyu line. These two routes are intended to form a wide- area railway network that directly connects the western part of Yokohama City with a central area of Kanagawa Prefecture and the center of Tokyo and to provide enhanced functions.
When service begins, it will reduce travel time and the number of transfers needed, improving railway convenience and providing stimulation to the region and so on. It will also improve access to the bullet train and help further development in the Shin-Yokohama subcenter and other areas.
SENS is used in two tunnels on these two lines. In the first one is Nishiya tunnel on the Sotetsu-JR through the line, and the other is the Hazawa tunnel on the Sotetsu-Tokyu through the line. This chapter reports character- istics of SENS tunneling. Shield machine SENS. View after primary lining concrete placement. SENS is a tunnel support system in which, while the ground is being initially excavated using a sealed earth pres- sure balance type shield tunneling machine with the face being stabilized at the same time , concrete is pressurized at the shield tail section and placed to provide Extruded Concrete Lining ECL that will serve as the primary lining to support the tunnel, concurrently with the shield tunneling excavation.
Figure 32 shows the status after placement of the primary lining concrete. Subsequently, the sta- bility of the primary lining is confirmed by taking measurements, and at the same time the New Aus- trian Tunneling Method is used to construct the secondary lining to complete the tunnel. The Nishiya tunnel is a double-track railway tun- nel of total length 1, m located between the.
Hazawa station tentative and the shaft near Nishiya station. The earth covering of the tun- nel varies between 6 m and 46 m. One of the characteristics of SENS is that the primary lining is made of cast-in-place con- crete, so the earth pressure at the face and concrete placement pressure could cause displacement of the ground surface. The Nishiya tunnel crosses under an arterial road Route 16 with overburden of approximately 6. Route 16 has heavy traf- fic approximately 25, vehicles daily. Also, as shown in Figure 33 , there are numerous utilities beneath the Route Widespread ground displacement would have an extremely large social impact, so, in this case, it was necessary to set appropriate limits for the earth pressure at the face and the concrete place- ment pressure in order to avoid affecting such facilities.
Therefore, the method for setting control values for the earth pressure at the face and con- crete placement pressure was determined based on the construction results in a trial zone provided within the starting yard. Figure 34 shows the results for the two points with the largest displacement from manual meas- urements and the measurements made using set- tlement rods. Plan and cross-section view of Route The Hazawa Tunnel is a double-track railway tunnel of total length 3, m located between the shaft near Hazawa Station tentative and the Shin-Yokohama Station tentative.
From Hazawa shaft there will be m of cut and cover tunnel, and 3, m of circular tunnel. The circular tunnel section will be excavated by the mud pressure shield method, and both SENS and shield method segments were adopted as the lining. This tunnel approaches to closer than 1D to the foundations of the overpass of the Daisan- Keihin highway, the foundations of the viaduct and the piled foundations of the overpass on No.
From the geology through which the tunnel passes is the same as Nishiya tunnel, it has been judged that the SENS can be applied to Haz- awa tunnel. Also, the shield that was used on the Nishiya tunnel will be used on this tunnel to achieve further cost reductions. Hazawa tunnel is a combination of cast-in- place lining and segments.
Because, investigation of lining load resistance in reaching the side, as a result of the nearby effect analysis in the starting side, so it was not applicable in the cast-in-place lining. Accordingly, since the segment sections are on the starting side up to m and m from the arrival side, the SENS section is the remaining 2, m.
Adopting segments for a part of the lin- ing, so it is necessary to change a part of the shield device hereafter referred to as the conversion. Figure 35 shows the jack positions during exca- vation both SENS and shield method. The instal- lation positions of the inner form and the segments are different, so it is necessary that the advance jack be compatible with both.
Therefore, by ena- bling the spreader positions on the rod head of the advance jack to be changed, it is possible to use it for both inner form and segments. SENS and shield method. The construc- tion will be carried out by paying great care not to adversely affect the important structures nearby. Tokyo Metro Co. The Tokyo Metro Tozai Line traverses the city center on the The line began running in its entirety in and is used by an average of 1. Through train services with two other railway companies are available from the Tozai Line, as shown in Figure The number of passengers has increased each year as development progresses around stations of both the Tozai Line and the through train service lines.
Tokyo Metro is proactively revising schedules, introducing wide-door trains, expanding platforms. Minami-sunamachi Station was built during a period of high economic growth in Japan. At the time, the surrounding area was an industrial zone, but the station was built there with future urban planning in mind. Renovation work to improve passenger services, namely adding entrances and establishing Barrier Free access routes from ground level to underground facilities, has been imple- mented sequentially since the station opened. The station is located in the delta region of the Sumidagawa River, Arakawa River and Edogawa River, which comprises a deeply stratified and widespread alluvium deposit due to the effects of the rivers.
Figure 37 is a standard cross-section that includes geological conditions. The layer from ground level to roughly four meters below consists of fill dirt, but below that is an extremely soft, cohesive alluvium deposit with N-values between 0 and 1. The pneumatic caisson method was used to con- struct the station because it was located beneath the Susaki-gawa, a canal that connected to the former coastline.
However, development around the station progressed and the canal was reclaimed in as part of a strategy for more effective land use. Now Minami-sunamachi Station lies beneath roads and privately owned land. The following measures will be taken under this renovation plan in an effort to improve transporta- tion on the Tozai Line and mitigate congestion on the station platform see Figure Relocate platform stairways: relocate and increase the number of stairways in the center of the platform to disperse the passengers climbing and descending them in an effort to.
Presently, Minami-sunamachi Station comprises one platform between two tracks, and station. Relocate station spaces: relocate passenger wait- ing areas, restrooms, and other station spaces to the center of the station and expand facilities in an effort to improve services; and. Functionality to mitigate delays. Add one platform and track: total of two plat- forms and three tracks as shown in Figure 40 , in an effort to equip the station to absorb delays, accomplished by reconfiguring the station such that the succeeding train can enter the station during delays caused by the time required for passengers to exit and board the preceding train.
This renovation work involves using the open-cut method within an extremely soft, cohesive alluvium deposit. The ground improvement work under the exist- ing structure is being performed from inside the structure with the small ground improvement machine shown in Figure 42 to retain the weight of the earth above the existing frame in an effort to keep the existing structure from rising and skewing the track alignment or damaging the structure. However, the fact that the ground improvement is being performed with a machine located inside the existing structure limits the working hours to the two-hour, minute period from to when trains are not operating.
Construction for this renovation work is in progress. The goal is to complete it in time to put the new structure into service in At present, the reinforced concrete diaphragm wall is being built in preparation for excavation, and the ground improvement work beneath the structure is under way. Further excavation of extremely soft ground.
This paper summarizes the geotechnical aspects of current underground construction activities in Japan, which are amazing the international geo- technical engineers with wide open eyes. Included are the MAODC, the expansion and the production of the underground expressway, Chuo Shinkansen bullet train, the connection of the new urban train system and the renovation of the existing subway station, in order to demonstrate the active underground construction for the Tokyo Olympics in The followings are the conclud- ing remarks on the listed underground construction. MAODC has been built with the large under- ground shrine cave and been utilized to reduce the flood damage of the north of Tokyo area.
Metropolitan expressways have been built with the large diameter shield TBM and the in-situ. Gaikan expressway project will be finished with the large diameter shield TBM tunneling and the large underground space production with the underpinning. Pneumatic caisson method: a construction condition was seriously severe because the separation was only 2.
Afterward, we confirmed the influence on the viaduct by 2D Finite Element Method in advance and a counter- measure based on the consideration results was devised, and then the construction works were completed safely. Isolation barrier wall was constructed between the viaduct and the box culvert in order to reduce the nega- tive influence.
Also, the heads of the protection work were connected each other to prevent the ground surface settle- ment during the caisson work. Four press-in ground anchors were used together to prevent the inclination and loosening of the ground and to improve the construction accuracy. Underpinning: the 52 oil jacks were distrib- uted on newly-built girders and piers and then load supported by the existing piers were replaced with new ones step by step. Rubber shoe and stopper were set on each shoe seat and after the girder structure was completed, the piers of the viaduct were cut and removed.
Geotechnical Aspects of Underground Construction in Soft Ground
During the replacement work, we could restrain the displacement of the existing viaduct within the range of the allowed value in train operation. SENS tunneling method has been utilized for the underground construction of urban train track system, which connects the existing train systems. Tunnel group construction of Chuo Shinkansen is quite difficult, when viewed from the tunnel construction achievements in Japan and includes the long shield tunnel in the urban areas and the mountain tunnel.
The development of the future of the construction plan, using the latest technology related to measurement evaluation and construction methods as much as possible will reduce the impact on the environment and achieve the safety and economic efficiency. Old existing subway system has been renovated with the underground geotechnical construc- tion technology in soft ground.
In Japan, lots of larger cross-section, longer span and deeper underground construction projects are. These geotechnical engineering experiences mentioned here and the geotechnical engineers are sure to contribute the development of worldwide underground construction projects in soft ground. The original draft for this second Fujita lecture was prepared by the members of the Japanese national committee for TC, supported by the Japanese Geotechnical Society. The names of the committee members are listed below and highly appreciated. The author is greatly grateful to their excellent contribution to this second Fujita lecture in IS Sao-Paulo, and to Mr.
Alireza Afshani Waseda University for his revis- ing the manuscript. Iida, H. Cast-in-place support system using shield machine in an unconsolidated mountain area contain- ing water, Waseda University Dissertations. Miyao, H, Kamoshita, Y. Nakanishi, K. Sakata, A. Read Free For 30 Days. Flag for inappropriate content.
For Later. Related titles. Carousel Previous Carousel Next. Jump to Page. Search inside document. Conselho Nacional de Desenvolvimento. Figure 1. Overall length 6. Figure 3. Table 1. Specification of banks. Horizontal cotter type joint. With this method,. C-type metallic material. When assembling a segment, H-type met allic material is inserted from. Overall structures of ramp section. Bending moment : M. Shear Force : S.
Axia I Force : N. Skin Plate. Upper Slab of. However, there. STEP I. Construction of SM W earth retai nin g walls. ST EP2. Internal reinforcement of tunnel and. S TEPJ. Construction of the top slab of t he. Th e ground excavate d to the floor depth of. Construction of b otto m s lab of frame. B ack filling. Safety factor for collapse of the ground and. Completion image. Geological features. Overview of the construction. Pneumatic cai sson.
Step pneumatic caisson method. About 13m. Yamamtshi te nninal. Kanagawa te rminal. C'Ji l'u Lem 1ina l. Nagoya tem1 ina l. Route map. Perforated panel. Silencing equipment. Overview of this emergency exit. Standard sectional view of the mountain. The jack positions during excavation both. Tozai line overview. Present state. S :Ticket machines. After completion. Before Renovation. After Renovation. Comparison of standard cross-section. Une 1. I stirring method. Ground improvement work within existing. Sreejith Reddy Sree.