Trench Cutter Research Articles

Construction of Plastic Concrete Seepage Cut-Off Wall for Polavaram Earth Cum Rockfill Dam

Abstract: Polavaram Project is being executed on River Godavari near Ramayyapeta village of Polavaram Mandal, West Godavari District, Andhra Pradesh. This multipurpose major project envisages construction of 2454m long Earth-cum-Rock fill (ECRF) dam across river Godavari near Polavaram with a maximum height of 50.32m. The proposed ECRF dam will be founded on a bed of sand. The depth of sand bed over the underlying rock strata varies from 30m to 90m at different location. To restrict the flow of seepage water through the sand bed, a plastic concrete diaphragm wall/Cut-Off wall is proposed with its top end embedded in the clay core of the ECRF Dam and the bottom end embedded into underlying hard rock. The wall was constructed of plastic concrete using panel construction method. Plastic concrete was selected to provide a seepage Cut-Off wall that has sufficient strength to withstand both static and seismic stresses beneath the new embankment, and yet is flexible enough to undergo seismic deformations, without cracking, with the surrounding soils. This paper illustrates the construction of the plastic concrete Cut-Off wall for the Polavaram ECRF dam, including the field and laboratory testing performed to confirm design wall stiffness, strength, and hydraulic conductivity requirements. The trial laboratory and field testing programs to determine plastic concrete mix design, and the QA/QC testing conducted during construction are presented. Keywords: ECRF, Plastic concrete, Cut-Off wall, Hydraulic grab, Trench cutter, Koden, Tremie

SUPPORT FOR OFFSHORE MONOPILE INSTALLATION THROUGH THE TRENCH CUTTER TECHNOLOGY

Europe is currently facing an energetic revolution. Several offshore wind farm projects are currently under construction or under planning in North and Baltic Sea. Typical foundation structures for offshore wind farms are steel open-ended monopiles with large diameters up to 6 m. Currently, the monopiles are installed by driving with large impact hammers. However, there are many situations where pile refusal is reached, due to hard soil layers or erratic blocks. Driving and drilling technique is therefore applied. This manuscript briefly describes the trench cutter technology normally used for foundation works on land. Three case histories onshore and one offshore project are discussed and the evolution of the trench cutter technology for supporting the installation of offshore monopile is described.

Flap-sparing canaloplasty: a modified approach to Schlemm's canal.

To present a modified surgical technique for canaloplasty with the Stegmann Canal Expander obviating the need for lamellar scleral dissection. After limbal peritomy of the conjunctiva, the sclera is not dissected in the classic lamellar fashion with superficial and deep scleral flaps but is successively 'scratched' down by radial incision until Schlemm's canal (SC) is opened (trench cut). Following canal opening and viscodilation with a microcannula and sodium hyaluronidate, one Stegmann Canal Expander is implanted on either side of the canal ostia and the scleral incision is closed watertight. Twenty-seven eyes with primary open-angle glaucoma (POAG) were consecutively operated on using this modified technique. In all eyes, SC was successively opened, but exposure of the choroid and rupture of trabeculo-Descemet's membrane with iris prolapse or filtering blebs were not found. Adverse events included trimming of the expander in one eye for incomplete implantation during surgery, and transient microhyphaema in five eyes post-surgery. Mean intraocular pressure (IOP) was 31.9mmHg ± 6.0 (SD) before surgery and 14.0mmHg ± 2.5 (SD) 6months and 15.2mmHg ± 1.95 (SD) 12months after surgery. The flap-sparing, trench-cut incision technique may reduce the risk of complications in canaloplasty with the Stegmann Canal Expander while effectively lowering IOP in POAG patients.

Testing the Fill‐and‐Spill Model of Subsurface Lateral Flow Using Ground‐Penetrating Radar and Dye Tracing

Core Ideas Lateral flow patterns revealed by dye tracing agreed with time‐lapse GPR data. Lateral flow downslope varied from <1 to 1 m at adjacent sites. 3D radar detected banding in the strike direction but dye fingering did not. Fractured saprock modifies the fill‐and‐spill model by facilitating vertical flow. Preferential flow (PF), which bypasses large portions of the soil or subsurface matrix, is critical in the transport of water and dissolved constituents in the unsaturated zone. To test the “fill‐and‐spill” model of hillslope hydrology that describes the generation and pattern of downslope lateral PF after storms, we used dye tracer and time‐lapse, ground‐penetrating radar (GPR) on a forested hillslope in the Susquehanna–Shale Hills Critical Zone Observatory. We injected 50 L of water mixed with Brilliant Blue dye (4 g L−1) into a shallow trench cut perpendicular to the slope and used GPR to monitor the tracer downslope across a 1.0‐ by 2.0‐m grid. The site was then excavated to the soil–saprock interface and photographed to document the dye pathways. We observed vertical dye fingering near the infiltration trench. Downslope lateral PF at the soil–saprock boundary was limited to ~0.40 m, which is evidence that the soil–saprock interface did not fill‐and‐spill. The extent, depth, and direction of the downslope PF indicated by GPR generally matched the dye staining patterns in the excavation, but the resolution of the 800‐MHz GPR antenna was insufficient to distinguish small fingers of dye. A revised fill‐and‐spill model was proposed for this site that incorporates the PF through fractured saprock before water encounters fresh bedrock surface. This study demonstrates that GPR integrated with dye tracer infiltration can provide a useful means of testing hillslope hydrological hypotheses and unraveling the complexity of PF at the hillslope scale in a field setting.

Adaptive fuzzy integral sliding mode pressure control for cutter feeding system of trench cutter

A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system (CFS) of trench cutter (TC) in the presence of unknown external disturbances. The feeding pressure control of CFS is subjected to unknown load characteristics of rock or soil; in addition, the geological condition is time-varying. Due to the complex load characteristics of rock or soil, the feeding velocity of TC is related to geological conditions. What is worse, its dynamic model is subjected to uncertainties and its function is unknown. To deal with the particular characteristics of CFS, a novel adaptive fuzzy integral sliding mode control (AFISMC) was designed for feeding pressure control of CFS, which combines the robust characteristics of an integral sliding mode controller and the adaptive adjusting characteristics of an adaptive fuzzy controller. The AFISMC feeding pressure controller is synthesized using the backstepping technique. The stability of the overall closed-loop system consisting of the adaptive fuzzy inference system, integral sliding mode controller and the cutter feeding system is proved using Lyapunov theory. Experiments are conducted on a TC test bench with the AFISMC under different operating conditions. The experimental results demonstrate that the proposed AFISMC feeding pressure controller for CFS gives a superior and robust pressure tracking performance with maximum pressure tracking error within ±0.3 MPa.

Preliminary Design of a Trench Cutter System for Deep-Sea Mining Applications Under Hyperbaric Conditions

Seafloor massive sulfides (SMSs) are formed as precipitation products from hot hydrothermal fluids as a result of mixing with cold seawater and are mostly found at depths between 1500 and 3600 m. These deposits are formed in tectonically active zones of oceans (midocean ridges and “back-arc” spreading systems) and are the result of the global heat transfer from the mantle in the oceanic crust. As these fluids mix with the cold surrounding seawater, metal sulfides in the water are precipitated on or in the nearby seabed. The appearance of the solid mineral occurs as cylindrical chimney structures: the so-called black and white smoker (caused mainly by the presence of iron, copper, zinc, and sulphur). Larger sulfide occurrences are mostly originated in several generations of hydrothermal cycles, and they form deposits that can range from several thousands to about million tons. SMS contains pyrite (iron), galena (lead), sphalerite (zinc), and chalcopyrite (copper). Deep-sea mining is concentrating now to exploit such deposits. So far, the only known commercial project is the one developed by Nautilus Minerals, which is based on a horizontal system. This paper describes a preliminary design of a novel cutting tool developed for a vertical mining approach. The vertical mining method is preferred when rough terrain is expected and the device is easy to relocate. Using an atmospheric and hyperbaric cutting model, the cutting energy for two selected SMS deposits has been estimated and validated with real onshore excavation sites performed with a cutting tool normally used for diaphragm wall installation (i.e., the trench cutter technology). Preliminary results suggest that the estimated cutting energy ${\bf E}_{\bf SP}$ is 2.9 times higher with respect to the measured one in atmospheric conditions. This could be because the model considers the worst case scenario, i.e., higher energy due to the maximum cutting forces assumed. This factor has been used to design a cutting tool which is able to work up 2000-m water depth to mine SMS deposits.

Preliminary Study of Ultrasonic Assisted Underwater Laser Micromachining of Silicon

The disturbances of vapor bubble to a laser beam in the underwater laser machinig process importantly limits the material removal rate and cut quality obtained. This issue is more essential for the laser micromachining process that a precise and small trench cut is highly needed. In this study, the ultrasound was used to energize and break up the bubble while the laser beam was performing a cut in water. Silicon was used as a work sample in this study as its significant usage in many micro-components. An ultrasonic transducer was located nearby the workpiece in an attempt to vibrate surrounding water. The results revealed that an increase in ultrasonic power increased the width and depth of cut channel. In addition, the workpiece surface obtained after the ablation was clean as similar to that performed by the ultrasonic cleaning. This combination of laser machining and ultrasonic cleaning processes can be another effective approach to cut thermal sensitive materials and also small components whose thermal damage and deposition of cut debris can be harmful to their functionality after laser ablation.

Adaptive fuzzy integral sliding mode velocity control for the cutting system of a trench cutter

This paper presents a velocity controller for the cutting system of a trench cutter (TC). The cutting velocity of a cutting system is affected by the unknown load characteristics of rock and soil. In addition, geological conditions vary with time. Due to the complex load characteristics of rock and soil, the cutting load torque of a cutter is related to the geological conditions and the feeding velocity of the cutter. Moreover, a cutter’s dynamic model is subjected to uncertainties with unknown effects on its function. In this study, to deal with the particular characteristics of a cutting system, a novel adaptive fuzzy integral sliding mode control (AFISMC) is designed for controlling cutting velocity. The model combines the robust characteristics of an integral sliding mode controller with the adaptive adjusting characteristics of an adaptive fuzzy controller. The AFISMC cutting velocity controller is synthesized using the backstepping technique. The stability of the whole system including the fuzzy inference system, integral sliding mode controller, and the cutting system is proven using the Lyapunov theory. Experiments have been conducted on a TC test bench with the AFISMC under different operating conditions. The experimental results demonstrate that the proposed AFISMC cutting velocity controller gives a superior and robust velocity tracking performance.

Trench Cutter Case Histories and Their Possible Application for Offshore Piles as Relieve Drilling

As of 30th June 2013, according to the European Wind Energy Association, there are 1,939 offshore wind turbines, with a combined capacity of 6,040 MW. They are fully grid connected in European waters in 58 wind farms across 10 countries. About 70 % of the foundations used for wind energy are monopiles with a diameter up to 6 m. The monopiles are installed by using hammers. However, there are situations where the piles cannot be installed without the “driving and drilling technique”, above all in the glacial areas, where glacial tills, boulders or cobbles can be encountered. A new technology for supporting the installation of monopiles is the monopile-trench cutter. The following paper describes four onshore trench cutter case histories in hard geology. Based on several projects, a correlation between net cut performance and uniaxial compressive strength (UCS) values of the in situ rock is briefly described. The variation of the cut performance decreases logarithmically with increasing UCS values. However, the data showed are only based on projects already performed, and it is not possible to extrapolate the data for future projects in similar geological conditions. The findings of this paper want to show how the trench cutter technology might be a suitable technology for supporting monopile installation in difficult sea beds. Besides, the information contained in this manuscript wants to be an aid for contractors involved in offshore pile installation.

Support for Offshore Monopile Installation Through the Trench Cutter Technology

Europe is currently facing an energetic revolution. Several offshore wind farm projects are currently under construction or under planning in North and Baltic Sea. Typical foundation structures for offshore wind farms are steel open-ended monopiles with large diameters up to 6 m. Currently, the monopiles are installed by driving with large impact hammers. However, there are many situations where pile refusal is reached, due to hard soil layers or erratic blocks. Driving and drilling technique is therefore applied. This manuscript briefly describes the trench cutter technology normally used for foundation works on land. Three case histories onshore and one offshore project are discussed and the evolution of the trench cutter technology for supporting the installation of offshore monopile is described.

Geoconservation and the advancement of geosciences: lessons from the Chalk of England

Abstract Seven examples from the Chalk of England illustrate the importance of geoconservation to advances in understanding Upper Cretaceous Chalk geology and wider studies relevant to society including construction projects, groundwater investigations and environmental change. Two field sections are now lost to landfill (Asham, Lewes and Downend, Portsdown) and five are extant (Southerham Grey Pit, Lewes, South Lodge Pit Taplow, Berkshire, Peacehaven Cliffs and Eastbourne Cliffs, Sussex). Each of these field sections shows the range of geology that needs to be considered in any conservation strategy. Continued access to such coastal and inland field sections is vital so that new ideas and techniques can be tested and re-measuring and re-sampling can take place.The need for field sections has, and continues to be, challenged and there is a view that borehole cores can provide sufficient reference material to replace field sections. The inadequacies of a borehole alternative to field sections are illustrated with examples from Southerham Grey Pit, Lewes and Downend Quarry, Portsdown, Hampshire. These two sites also illustrate that a trench cut to replace a quarry face will not guarantee exposure of an equivalent geology. There are wider implications for society as field sections are essential for interpreting the geology beneath London and Stonehenge for tunnels and aquifer studies. Local field sections are also part of new initiatives, through the Lewes Railway Land Wildlife Trust, to widen understanding of and integrate geosciences with other natural sciences through environmental education to better inform decisions on environmental issues.

Entero‐urethroplasty for the salvage of bulbo‐membranous stricture disease or trauma

To describe a salvage procedure for bulbo-membranous stricture disease or trauma. Over a 10-year period 11 patients with otherwise unsalvageable strictures of the bulbo-membranous urethra or defects after trauma were treated by interposition of a tailored intestinal flap. An intestinal flap, on average 8 cm in length, was harvested from the ileum, the stomach, the right colon or (preferably) the sigmoid colon, and tailored to a calibre of 26-30 F. It was then sutured between the stump of the prostate and the distal bulbar or proximal pendulous urethra either following the normal perineal route for the urethra or a more direct route through a trench cut in the superior pubic ramus. Three patients developed proximal anastomotic contractures requiring interval dilatation in one and revision in two. Two patients developed a stone in the gut segment one of which was removed traumatically causing irreparable damage to the neourethra. The results were otherwise satisfactory. For an otherwise unsalvageable bulbo-membranous stricture or defect, a tailored flap of intestine, preferably sigmoid colon, gives satisfactory results. Of the two potential routes for the neourethra, we have more experience with the normal route but the direct route has several advantages.

A compact in-line polarimeter using a Faraday rotator

We have developed a compact in-line polarimeter for monitoring the polarization of light in active fiber. It consists of two parts: a half-mirror inserted into a trench cut at a slant across the fiber so that it reflects a portion of the optical beam and the combination of a magnetized Faraday rotator plate sandwiched between mirrors and a four-channel detector.

The Imperial Family as Seen in Cyrene

In the summer of 1989 a new electricity cable was laid from New Shahat to the Caesareum of Cyrene, its course following the line of the road made in the 1920s through the (now largely abandoned) village of old Shahat. The construction of the road had already revealed several blocks of an engaged Doric architectural order in the unexcavated southeastern quarter of the ancient city; from the trench cut in 1989 were recovered parts of eight marble sculptures susceptible of interpretation, less identifiable fragments of other figures in marble and limestone, and a number of ashlar blocks with drafted margins cut in local limestone. Though the architectural finds suggest the presence of a substantial public building, the sculptures were apparently found packed in a row, giving the impression of having been deliberately buried during preparation for transit to a lime kiln. Without excavation no more can be said of their original context, beyond what may be gleaned from an examination of the sculptures themselves.This paper is concerned with six of the more complete marble statues, which form an interesting, if not aesthetically distinguished group of portraits of members of the first Roman imperial family. The six survivors fall into three sub-groups, which are briefly described below; there follows an assessment of the relationship of the statues to contemporary portraits of the imperial family from Cyrene and elsewhere.Two of the statues are carved in Pentelic marble, and are of exceptional scale. Of these the better preserved is a figure of a woman originally cut from one block to stand about 2.10 metres high but now sliced from top to base through the thicker part of the lower torso and horizontally through the whole torso into pieces 20–30 cm high, presumably to facilitate delivery, perhaps by hand, to the lime kiln (Figs 1–2). The unveiled woman is dressed in tunic and cloak, the latter swept over her left shoulder in the manner of the Kore of Praxiteles, a type well known in the Cyrenaican repertoire. The cloak is drawn far from the right side of her body, suggesting that her right forearm, now lost, was raised to hold an object (Fig. 3, right). The hair is waved to either side of a central parting, and drawn back from the face in thick tresses which are massed wide of the head to fall into a looped plait below the nape of the neck and over the edge of the cloak (Fig. 4). Around the face is a row of pin-wheel curls; there is no break in the curls at the central parting of the hair, and the curls come close to the ends of the eyebrows. The lower earlobes are exposed. The face is broad and round, with a low brow accentuated by the hairstyle, plump cheeks and a small receding chin. The nose and mouth are badly damaged, but the mouth appears small. The eyes are large, round and wide-set (Fig. 5).

Design and construction of Revelstoke earthfill dam

The Revelstoke earthfill dam, located on the Columbia River in Central British Columbia, consists of a central till core with upstream and downstream granular shells. A core trench up to 76 m (250 ft) deep had to be excavated through the overburden in order to found the core on rock and approximately 7.6 × 106 m3(10 × 106 yd3)of overburden was removed. In one area, the core trench was excavated through 61 m (200 ft) of soft wet silt and clay. The dam axis crosses two deep buried channels and adjustments were made in the design to suit field conditions. Electroosmosis treatment was used to stabilize the core trench cut slopes in the area of the soft wet silt. Extensive field and lab testing was carried out to determine the density and strength of the overburden material. Empirical and analytical methods were used to assess the liquefaction potential under seismic loading of the silt/clay and fine sands under the shells of the earthfill dam.The Revelstoke earthfill dam was about 57% complete by the end of 1981. The construction has proceeded well and is on schedule. It is expected that the earthfill dam will be completed by mid-1983, well in advance of proposed reservoir filling in the fall of 1983. Keywords: excavations embankment design, foundation treatment, liquefaction, construction, electroosmosis.

Marine geology of abyssal plains in the Gulf of Alaska

Acoustic reflection profiles in the Gulf of Alaska afford a new geologic dimension that allows tests of many previous speculations and hypotheses about the marine geology of the three abyssal plains that surround a central area of hills and seamounts. The bulk of sediments forming the two eastern abyssal plains (Alaskan and Tufts) have been transported by turbidity currents from continental sources through many leveed channels. The undulating, partly buried topography beneath the plains is of volcanic origin, and the central hilly area is a high that antedated the deposition of the plains. The moats, or depressions, around hills and seamounts were formed by differential deposition; ponding behind ridges is common. The distinctive features of fourteen channels crossed in the northern Tufts plain are the flat beds within the channel proper, a lower levee on the east side, and a very wide higher levee on the west side (downstream, right-hand side); some channels were originally controlled by lows in the underlying topography; channel migration upward and away from the high-leveed side is apparent. These channels are depositional rather than erosional in origin. Turbidite thicknesses decrease with distance from continental sources. In the southeast part of the Alaskan plain sediment thickness is 680 meters; in the northern Tufts plain maximum thickness is 470 meters, and in the southwest part it is 145 meters thick. The Aleutian abyssal plain, west of the central hilly area, has no present-day source of bottom-transported sediments; it is a fossil turbidite plain (maximum thickness, 282 meters) covered, in the west-central part, by 96 meters of pelagic material. Sediment thicknesses, probable rates of deposition, and known geologic history in adjacent areas, indicate the following geologic history: During Late Cretaceous to middle Tertiary the southward extension of deep-water flysch deposits (from the Alaskan peninsula area) formed the fossil turbidite Aleutian abyssal plain. In early to middle Tertiary, the first down-bowing of the Aleutian trench cut off turbidite deposition, and pelagic deposition began; the East Pacific rise was elevated. In middle Tertiary, the East Pacific rise subsided and great effusions of volcanic material from crestal areas covered the adjacent sea floor; turbidite deposition began over the Alaskan and Tufts plains (formerly the west flank of the rise). Pelagic deposition on the Aleutian plain continued to the present; turbidite deposition continued through the Pleistocene on the Alaskan and Tufts plains. It is concluded that the East Pacific rise in the Gulf of Alaska is in an advanced stage of rise evolution, and that the whole area has been quiescent since middle Tertiary.