Ritom Pumped-Storage Plant Project – Tunneling under extreme conditions

thank you May 2019 lager returned to Chino Marty subsidiary albertek is installing a construction water purification plant at the Lake's retaining wall the plant needs to be flown in so it has to be small as well as Innovative it will purify the water of the tunnel construction site on a highly efficient basis it's actually a good example of successful nature conservation but later when building the tunnel the conditions deep in the mountain were extremely difficult greatly complicating The Tunnel construction project in every way imaginable that's what this film is about the project spb's retom Hydro Power Station built more than 100 years ago is to be expanded and have its output quadrupled in order to improve the power supply to the godhard rail line the pressure line to Lago riton which is around 800 meters higher was rooted partially above ground but must be relocated completely underground as it's being greatly enlarged but the three exploratory balls on the tunnel axis made in advance showed that the rock is tricky to deal with down to a depth of around 200 meters and is crisscrossed by poor estrata that are also aquiferous in part so conditions are pretty bad for Tunnel construction so the first step is to build a gallery into deeper regions of rock that are presumably easier to work with only here is the slope shaft to begin rising to the lake level to remain as deep as possible the shaft is also being built with an inflection in its root as well as two different slopes the shaft has a diameter of 3. 2 meters it will be excavated using a tunnel boring machine that Martian manufacturer Heron connect developed especially for this project the difficult Rock and the slope of nearly 45 degrees present extreme challenges but more on that later [Music] the sloped shaft is roughly 1400 meters long and ends in an arrival Cavern created in advance known as the slide chamber from here the Headwater Gallery will lead into the lake work on the project begins in January 2019 with the construction of the lower pressure gallery [Music] after blasting loose Rock has broken off and the tunnel profile is excavated the tunnel is lined with a shot grate and reinforced with steel arches where necessary the gallery is used to cross the aquiferous rock strata and as the driving operations progress ice cold Alpine Water becomes a constant companion for the miners about 250 blasting stages are planned with more than 20 000 holes for explosive charges working under these conditions is an extreme Challenge for the body as well as the will to persevere danger is not posed by the water because the water entering the construction site is only under low pressure and the special explosive charges perform perfectly even under wet conditions the tunnel is on their way to work also hope that after about 400 meters of driving operations they would pass through the fissured and aquiferous Rock area and reach rock that was largely dry as per the geologists forecast however it was here that enormous problems arose after another blast there was a strong Ingress of water under high pressure of 10 bar corresponding to a water column of 100 meters in height under such conditions it would be irresponsible to venture further into unknown Rock for this reason an exploratory boar was drilled by Marty's subsidiary stump BTE which specializes in geologically deep Drlling during retraction of the drill string to recover the cause water repeatedly entered the borehole at flow rates of up to 100 liters per second not a good sign after the Martyr geologists evaluated the Dual cause of the exploratory boar and the five unsuccessfully dual drainage boreholes it became clear contrary to the original forecast some of the rock they were dealing with was highly fragmented as well as quite aquiferous in part this jeopardized the continuation of construction as well as the entire project it was clear to Marty that to continue construction it would be necessary to use injection Shields to seal the area this process involves injection material being injected through poreholes to seal the aquiferous fishes first to protect the existing structure the last 10 meters of the gallery were backfilled with a concrete plug and the last tunnel section was sealed the concrete plug prevented the injection material that was pressed into the boreholes from leaking into the tunnel under the protection of the previously created Shield the plug was then broken up again now 20 meter injection shields were created on a periodic basis followed by the excavation of 15 meter tunnels due to the substantial flows of water in the Rock which according to Conventional wisdom is close to impossible to stop a hybrid injection of a conventional cement and a pure resin developed by Marty subsidiary renesco was used each injection began with cement if Rock areas with relatively small aquiferous fractures and minor flow are injected cement injections are adequate as very little cement is washed out after the borehole is backfilled the pressure in the hole increases the cement penetrates the fishes also against the water pressure and closes the fissure system around the hole however if Rock areas were the large fishes and a major water flow are injected the cement is largely washed away the pressure in the borehole does not increase and no injection takes place that's why pure resin was automatically added to the cement of the pressure did not increase or was too low the now greatly increased viscosity of the material did not allow for penetration into fine fishes but washing out of the injected medium was prevented leading to clogging of the large fishes when the resulting pressure increase occurred the system was switched back to Pure cement as in the conventional process the fine fishes were also largely sealed in this way that's the theory at least in practice each new injection ball leads to aquiferous rock areas and attaching the hoses for the injections is not a task for people who don't like water however the tunnel is perseverance and the Innovative injection process developed by Marty paid off to the astonishment of the experts it was possible to make it through the largely aquiferous and fractured stratum after construction of 14 injection Shields with nearly 1 000 injection balls they were then able to reach goodrock as the exploratory drilling had already demonstrated in February 2021 the shaft base cabin was built with a delay of nearly a year and construction of the launch ramp for the tunnel boring machine could begin the ramp guides the machines in the previously drilled start of the shaft and Maneuvers it to the initial slope of 26 degrees then the 80 meter long Cavern is ready and assembly of the tunnel Boring Machine TBM for short can begin the machine is delivered in six separate transports the drill head of the TBM has the largest diameter of course and the access Gallery is precisely dimensioned to accommodate it incidentally it's not an easy job for the truck driver the drill head is lifted from the low platform loader using special hydraulics the machine is 100 meters long when assembled to make room for additional deliveries it slides its way up the launch ramp during assembly then the time has finally come driving operations begin while other components are still being attached to the TBN [Music] while the drill head has already begun to operate the end of the TPM continues to be assembled in the launch Cavern blocking subsequent installations provisional Solutions are required for removal of the excavated material and to supply the machine the machine is completely in the Rock after three weeks of interim solutions that are constantly changing in the cavern and regular driving operations begin during drilling The Machine's 23 roller Cutters roll over the rock under high pressure breaking chips out of the Rock the loosened material falls into the cutting wheel and then into a material Channel the material slides down the sloped Chute by itself facilitated by the addition of water in the cutting wheel the required water which comes from the point of water Ingress into the access Gallery was previously used to cool the units of the TBM depending on the situation a wide array of clarifications as well as ancillary and additional work take place in the drill head during driving operations more on that later let's first discuss how the machine works during drilling four driving presses Force the cutting wheel up against The Rock with up to 500 tons of pressure more than the weight of the entire tunnel Boring Machine the gripper Shield absorbs the forces and uses its two driving grippers to brace itself in the rock a drilling stroke is 1. 2 meters long and normally takes about 30 minutes in the so-called driving Shield four hydraulic motors are mounted to drive the cutting wheel the resulting torque exerted on the driving Shield is absorbed by the vertically positioned compensating hydraulic systems to the combination of all the presses Each of which can be controlled individually the driving Shield which ultimately lies loose in the Rock must be continuously aligned and stabilized during Drlling this is how the TBM is controlled after the drilling stroke driving operations stop the trailing Hydraulics then Advance the gripper Shield once the grippers are re-tightened the machine resumes driving operations after the drilling stroke the TBM has been extended as far as possible before driving operations resume it's necessary for the entire rest of the machine to be drawn forward the remainder of the TBM consists of seven trailing units with the technical equipment to supply the machine and at Marty's request a redundantly designed full-back prevention device for Optimum safety this device prevents the machine from sliding backward down the sloped shaft and primarily consists of two pairs of fullback grippers using extremely powerful Hydraulics the rear pair of grippers can be moved on the Machine by about the length of a drilling stroke the grippers are seated on connecting rods and are spread by hydraulics if the grippers are in the Rock and the Machine wants to move backward the Gripp is automatically tighten in the Rock due to the sloped connecting rods halting the machine the self-inhibitory mechanism operates solely on the basis of its geometry functioning even in the event of an accident and loss of power on all hydraulics on the TBM in the event of total loss of power while a pair of grippers are attracted to move the machine these Hydraulics would be automatically ejected by emergency tanks with highly compressed nitrogen causing the self-inhibitory mechanism to be triggered on this pair of grippers as well this means that the machine is secured by both fullback grippers even in the event of a total failure only the gripper and the gripper's shield would lose its holding Force as it does not have a self-inhibitory mechanism and needs to be actively pressed into the Rock to be fixed in place let's now return to The Locomotion of the TBM after the TBM reaches its point of Maximum extension during drilling the front fullback gripper is retracted then the rear gripper which is fixed in place and the rock is slid backward and the Machine is pushed forward now the front gripper is fixed in place and the rear one is drawn forward once both fullback grippers are securely fixed and placed in the Rock the gripper Shield is released and advanced then the rear part of the machine is brought forward again the machine is now in the position of minimum extension driving operations Begin Again drill Advance the gripper Shield drill draw the machine forward Advance the gripper Shield draw the machine forward and drill again on the basis of this locomotive cycle the machine advances through the solid rock in 1.

2 meter increments on its deep path to the slide chamber 800 meters above it's continuously fixed in place in the rock using three pairs of grippers during Drlling and at least two pairs of grippers during locomotion let's move on to the slide chamber like the access tunnel it was constructed using the blasting method as with the access tunnel the conditions were not always completely dry I without all choking aside the explosive charges were reduced to protect the nearby retaining wall from vibrations nevertheless the blasts are impressive [Music] thank you the entire construction site must be supplied via the 38 meter deep access shaft managing the site Logistics with a material cableway is extremely complex all construction equipment in use must fit through the shaft that's why the shaft is oval in shape and has such a large diameter a slight chamber the power plants Works water system can later be shut down for maintenance purposes the pressure Gallery opens out at the wall on the southern end of the cabin the arrival Niche for the tunnel boring machine was already created [Music] on the other side of the cavern the 140 meter long Headwater gallery to Lago riton is driven the concrete finally reaches its place of installation here conveyed from the slide chamber by a concrete pump fresh from the valley and still warm steam arises from it and the Cold Mountain Air the Headwater Gallery is driven to within 20 meters of the lake the last part of the gallery can be constructed only in winter when the lake receives very little inflow and can be lowered to below the gallery another Gallery is being built for draining the cabin and later also for maintenance purposes [Music] during construction of the slide chamber the tunnel Boring Machine eats its way through the rock let's see how far they've come so far the peak speed at which we are flying around this animation is 600 kilometers per hour the TBM has progressed much more slowly than that in four months it has traversed 450 meters of rock and about 200 meters of altitude it can be reached from the launch Cavern via a tunnel Railway in the shaft the Alpine water entering the site runs down and the washed out excavation material is in the material Channel this means there's a risk of Falling Rocks but the train cabin offers protection on the tunnel wall there are pipes for Supply Water waste water and compressed air and on the other side fresh air and electricity the ride can take up to 20 minutes there's time here to relax to chat a bit or to discuss the situation finally they reach the tunnel Boring Machine this three meter thick worm showing its way through the Rock from here they continue toward the drill head taking the stairs over the trailing units at 3. 2 meters in diameter the TPM is very narrow and the existing profile is perfectly utilized the pipes of the Fresh Air Supply and the shaft for the excavated material hang under the machine a supporting structure in the stairs for the operating crew are above it a material cableway is rooted over all trailing units the profile for the cableway must be kept clear on all trailing units space is extremely tight and only what is absolutely necessary is kept on board the TBM of course there's a dust lock and an 11 kilowatt drilling rig on trailing unit 1 directly behind the fullback prevention device the ridge vault is secured here with rock nails and steel grids to protect the downstream work trailing unit 2 carries the indispensable air de-dusting system and a shotcrete pump trailing unit 3 is for the TBM control station and the hydraulic oil pressure pump with oil tanks on the other trailing units there are Transformers control cabinets and electronics hose reels for the water and Compressed Air Supply water pumps the Fresh Air Supply and the tunnel rail station the track for the tunnel Railway and the material channel are periodically extended through an assembly opening and trailing unit 6. there's virtually no storage space on the entire TBM and everything needed arrives from the launch cabin just in time [Music] quiet is prepared and delivered for direct use of it's necessary to perfectly coordinate All Transport operations because installation of the track segment blocks the cable way and all other material deliveries [Music] the material channel is extended between the rails the trailing units must be moved along and the men are working at Full Tilt the full back prevention device then takes another step through the mountain foreign travel of 1.