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December 06, 2019


“This article is a general knowledge about the micro tunneling specially designed for the safety officers in the field. The requirement and process may vary to be contingent on the site environment and circumstances. The below information is meant for general knowhow.”

Micro-tunneling is a digging process that uses a remotely controlled micro tunnel boring machine combined with the pipe jack-and-bore method to directly install pipes underground in a single pass.
Understand the process of micro-tunneling
This is a process often called pipe jacking and is repeated until the Micro-tunneling machine reaches the reception shaft. As the machine advances, more tunnel liner or pipe is pushed from the starting shaft, through the entry eye. Thus, the speed of the advancing machine is controlled by the speed at which the pipe is inserted into the entry eye via the extension of the hydraulic rams in the jacking frame.
These small diameters tunnels make it impossible to have an operator driving the machine itself.

Instead, the micro tunnel boring machine must be operated remotely from a control room
Micro tunnel boring machines are very like normal tunnel boring machines (TBMs) but on a smaller scale.

These machines generally vary from 0.61 to 1.5 meters (2 ft. into 4 ft. 11 in) but smaller and larger machines have existing today.

Usually, the operator controls the machine from a control room on the surface. The Micro-tunneling machine and jacking frame are set up in a shaft at the required depth.

The operator is given constant feedback about the machine’s location, orientation and hydraulic devices via a computer console or CCTV camera.

Most machines also have video cameras set up to enable the operator to monitor activities in the jacking shaft and at the separation plant.

The operator controls the MTBM and the jacking frame from the safety of the control room which is usually situated on the surface, next to the jacking shaft.

In addition to the jacking frame, smaller jacks, called “interjects”, may be inserted between sections of tunnel liner. These push the two sections of liner apart. Friction on the liner sections between the inter jack and the tunnel entrance helps to prevent the liner from sliding out backwards. So, while the liner behind the inter jack does not move, those sections in front of it receive additional pushing force.

Micro-tunneling shaft

The shaft is an excavation the requirement of how deep the tunnel to be made. The shaft act as entry eye of the micro tunnel and the tunnel boring machines.

The diameter of the shaft depends on the size of the tunnel boring machines and its mechanism this also includes:
The safe movement of the operatives as they often go to the shaft for the periodic inspection, maintenance, any emergency to attend, etc.

Adequate space for lifting operations for lower pipes, man baskets, materials and equipment required for the process of micro tunneling.

The shaft space to be adequate for all the mechanical pipe such as slurry and water pipe, hydraulic connection, air ducts or mechanical ventilation etc.

The shaft must have permanent access till to completion of work etc. are the main factor to be considered when making a shaft for the micro tunneling.

Micro Tunnel Boring Machine (MTBM)

A Micro tunnel boring machine, also known as a “mole”, is a machine used to excavate tunnels with a circular cross-section through a variety of soil and rock layers. They can bore through anything from hard rock to sand to clay. Tunnels of less than a meter are characteristically done using trenchless construction methods or horizontal directional drilling (HDD) rather than TBMs.


Components of tunnel boring machine

Micro-tunneling operations are managed by an operator in an above-ground control container alongside the shaft. Soil excavation takes place by way of infusing the soil with slurry at the face of the bore and cuttings are forced into slurry inlet holes in the MTBM’s crushing cone for circulation to and from a separation plant through a closed system.

A complete slurry micro-tunneling system usually includes a pipe specific MTBM
Control container
Guidance system programs
Remote hydraulic power pack and its connection components
Keyhole jacking frame
A series of pumps
Water cooling tank
Slurry and additional lines
A slurry separation plant.
Generator and backup generator

Associate activity for the setting up of micro tunnelling:
This section details the general setting up of micro tunnelling equipment and control system.

What shall a safety officer to be aware before the setting up of micro tunnelling are; a design, procedure, method statement, risk assessment and job safety analysis. The documentation shall be prepared by the construction management team and safety team to be familiar with the procedure and shall review for any missing item. The information below will help to give you a general knowledge of micro tunnelling but are not limited to for improvement safe practices.
Associated activities for the setting up of micro tunnelling: 
All the associated activities have discussed here for the setting up of micro tunnelling which gives you an insight into the hazards and the risk involved in the setting up process. The bellow information could be used for the preparation of method statement and risk assessment. This section mainly focused on the process nor discussing any hazards and risk involved.
Excavation of shaft for the boring entry and exit pit. The depth of the excavation is depending on the depth of tunnelling to be started. General excavation safety measures which must consist of the soil condition to adopt the suitable protection form edge collapse. The size of the excavation shall be decided considering safe access (preferably stairs), adequate space for liftings, Mechanical ventilation (Ducts), pipes and hoses etc.
Lifting process comprises setting up of crane, equipment, control cabin, panel, tanks, pumps, pipe, generators and other supporting items operated around the excavation (soil stability and a safe distance to be upheld from the excavation before installing). And lifting and lowering of tunnelling equipment, components and other items for micro tunnelling to the shaft. Selection of crane shall be the weight to be lifted in view of its angle, radius and total weight while it safe positioning at the edge of the excavation. Lifting and lowering into shaft will continue till the completion of micro tunnelling this might embrace the use of man basket.
Entry into the excavation/shaft. Excavation is considered as confide space considering depth, width, the equipment used in and around the shaft. Mistily the shaft for the entry of tunnelling bore is made very deep up to 20 meters or more to bypass all other underground utilities. Change of oxygen deficiency and build-up of toxic substance and fumes are unavoidable since all the procedural requirement and best practices to adhere to. Further, once the tunnelling process is started there could be continuous visits for installation, inspection, maintenance or any emergency to attend.
Assemble and installation of equipment and networks in and around the shaft which required moving and fixing of heavy machinery, manual handling, hot works, night works, movement of plant and equipment, electrical and mechanical installations, erection of structured, etc. Subsequently, the installation process will continue in the shaft for the tunnelling placing the heavy machines. This process will last to the end of tunnelling works for installing heavy tunnel ring, periodic maintenance and repairers (recommend a dynamic risk assessment).
Work at heigh to the shaft mostly requires here for the installation of slurry pipes, hydraulic hoses, Ducs, access etc consisting the use of scaffold a working platform and for short and light works using man basket and lifting. The work at height covers the erection of access of shaft.
Terjemahan bebas:

Kegiatan asosiasi untuk pengaturan terowongan mikro:
Bagian ini merinci pengaturan umum peralatan terowongan mikro dan sistem kontrol.

Apa yang harus diperhatikan oleh petugas keselamatan sebelum pemasangan terowongan mikro adalah; desain, prosedur, pernyataan metode, penilaian risiko dan analisis keselamatan kerja. Dokumentasi harus disiapkan oleh tim manajemen konstruksi dan tim keselamatan agar terbiasa dengan prosedur dan harus meninjau setiap item yang hilang. Informasi di bawah ini akan membantu memberi Anda pengetahuan umum tentang terowongan mikro tetapi tidak terbatas pada untuk meningkatkan praktik yang aman.

Kegiatan terkait untuk pemasangan terowongan mikro:
Semua aktivitas terkait telah dibahas di sini untuk pengaturan terowongan mikro yang memberi Anda wawasan tentang bahaya dan risiko yang terlibat dalam proses pengaturan. Informasi di bawah ini dapat digunakan untuk penyusunan pernyataan metode dan penilaian risiko. Bagian ini terutama berfokus pada proses atau membahas bahaya dan risiko apa pun yang terlibat.

Penggalian poros untuk lubang masuk dan lubang keluar yang membosankan. Kedalaman penggalian tergantung pada kedalaman terowongan yang akan dimulai. Tindakan keselamatan penggalian umum yang harus terdiri dari kondisi tanah untuk mengadopsi perlindungan yang sesuai dari keruntuhan tepi. Ukuran penggalian harus diputuskan dengan mempertimbangkan akses yang aman (lebih disukai tangga), ruang yang memadai untuk pengangkatan, Ventilasi mekanis (Saluran), pipa dan selang, dll.

Proses pengangkatan terdiri dari pemasangan crane, peralatan, kabin kontrol, panel, tangki, pompa, pipa, generator dan barang-barang pendukung lainnya yang dioperasikan di sekitar galian (stabilitas tanah dan jarak aman yang harus dijaga dari galian sebelum dipasang). Dan mengangkat dan menurunkan peralatan tunneling, komponen dan item lainnya untuk tunneling mikro ke poros. Pemilihan crane adalah beban yang akan diangkat dilihat dari sudut, radius, dan berat totalnya selama posisinya aman di tepi galian. Pengangkatan dan penurunan ke dalam poros akan berlanjut sampai selesainya terowongan mikro, ini mungkin mencakup penggunaan keranjang manusia.

Masuk ke dalam galian/poros. Penggalian dianggap sebagai ruang curhat dengan mempertimbangkan kedalaman, lebar, peralatan yang digunakan di dalam dan di sekitar poros. Mistly poros untuk masuknya lubang terowongan dibuat sangat dalam hingga 20 meter atau lebih untuk melewati semua utilitas bawah tanah lainnya. Perubahan kekurangan oksigen dan penumpukan zat beracun dan asap tidak dapat dihindari karena semua persyaratan prosedural dan praktik terbaik harus dipatuhi. Selanjutnya, setelah proses pembuatan terowongan dimulai, mungkin ada kunjungan berkelanjutan untuk pemasangan, inspeksi, pemeliharaan, atau keadaan darurat apa pun yang harus dihadiri.

Merakit dan memasang peralatan dan jaringan di dalam dan di sekitar poros yang memerlukan pemindahan dan pemasangan alat berat, penanganan manual, pekerjaan panas, pekerjaan malam, pemindahan pabrik dan peralatan, instalasi listrik dan mekanik, pemasangan struktur, dll. Selanjutnya, proses instalasi akan dilanjutkan di poros untuk penempatan tunneling mesin-mesin berat. Proses ini akan berlangsung hingga akhir pekerjaan tunneling untuk pemasangan cincin terowongan berat, perawatan berkala dan perbaikan (merekomendasikan penilaian risiko dinamis).

Pekerjaan di ketinggian hingga poros sebagian besar membutuhkan di sini untuk pemasangan pipa bubur, selang hidrolik, Duc, akses dll yang terdiri dari penggunaan perancah platform kerja dan untuk pekerjaan pendek dan ringan menggunakan keranjang dan pengangkatan manusia. Pekerjaan di ketinggian meliputi pemasangan akses poros.


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