Hydraulic Grab Research Articles

THE INFLUENCE OF PARAMETERS OF EARTHMOVING MACHINES ON THE DESIGN SOLUTIONS OF BARRETTE PILES

The article deals with the analysis of publications on the arrangement of barrette foundations. It indicates that the bearing capacity of a barrette is determined mainly by the resistance behind its lateral surface, and if it is larger, maybe, it will increase the bearing capacity of the barrette. The use of barrettes with a cross-sectional shape is more relevant than rectangular (square) one. Nowadays, rectangular (square), X-shaped, T-shaped, L-shaped, H-shaped, Y-shaped and C-shaped barrettes can be used in construction. The geometric dimensions of the barrettes depend on the size of a grab unit or a milling unit. A theoretical study of the parameters of the most common types of earthmoving machines, namely a hydraulic grab and a hydromill, was carried out. The technical characteristics of hydraulic grabbers were analyzed: KHD series (CASAGRANDE S.P.A.), GB series (BAUER Maschinen GmbH), HSG series (LIEBHERR Maschinen GmbH), GH series (SOILMEC S. P.A.) and technical characteristics of hydromills: FD series (CASAGRANDE S.P.A.), BC series (BAUER Maschinen GmbH), LSC series (LIEBHERR Maschinen GmbH), SH series (SOILMEC S.P.A.). The intervals of variations were determined in the geometric dimensions of a single gripper, which is arranged with the help of a grab unit and milling unit. It allowed to determine the possible variations in the geometric dimensions of rectangular (square), X-shaped, T-shaped, L-shaped, H-shaped, Y-shaped, and C-shaped barrettes with cross-sectional dimensions. According to the obtained results, the width of a separate linear element of the barrette can vary from 420 to 1800 mm during the use of a grab unit and from 64 to 2000 mm during the use of a milling unit. The length of a single line element of barrette can vary from 2200 mm to 4200 mm during the use of a grab unit and from 2200 mm to 3200 mm during the use of a milling unit. The obtained results will allow to optimize the design process of barrette foundations and avoid additional specification of their dimensions at the installation stage.

Application of “Drilling and Grasping Method” in the Design and Construction of Anti-seepage Walls

The anti-seepage wall has been widely used in many fields, and the construction technology is also various, such as high-pressure jet impervious wall, continuous grooving technology of hydraulic slotting machine, mechanical grab and hydraulic grab construction technology of impervious wall. Different technologies are applicable to different geological conditions, and it is often necessary to combine or even innovate different technologies in order to continuously improve the technical level and complete the construction tasks quickly, well and economically. Based on practical experience, the paper studies the construction of impervious wall by adding impact drill on the basis of traditional grab construction under the complex geological conditions of pebble gravel layer, pebble mixed soil, sandstone strongly weathered layer and weakly weathered layer, and expounds the “drilling and grasping method” adopted in the implementation process in detail, aiming to provide reference for future designers and constructors.

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

Clamshell vs. Backhoe Excavation of Permeable Reactive Barriers

Problem statement: Permeable Reactive Barriers (PRBs) were one of the most widespread solutions for the remediation of contaminated aquif ers. Although, a variety of excavation methods had been developed, backhoe (hydraulic excavators) were commonly used for the construction of PRBs in North America. Approach: In Europe, the most common method of slurry excavation was with a hydraulic grab and crane. The aim of this study was to compare clamshell and backhoe excavation techniques and to describe the installation of a fu ll scale PRB using a crawler crane equipped with a hydraulic grab. Results: Backhoes had been used on a larger number of PRB installations and permit a rapid rate of excavation and generally require less skill to master. Long stick backhoes were capable of digging as deep as 30 m. Instead, clamshell excavat ors require more skill to use, but were able to excavate to a depth of more than 70 m, with a high degree of precision. Two similar case studies were presented to compare the relative merits of the two excavation techniques. Conclusion/Recommendations: The first describes a funnel and gate system excava ted by long stick backhoe, in the US, whose longest gate is 0.73 m th ick, 68 m long and up to 13 m deep. The latter is a 0.6 m thick, 120 m long and 13 m deep continuous PRB, excavated by crane mounted grab to remediate a chlorinated hydrocarbons plume, in Avigliana, near the city of Torino, in Italy. Comparison of the two techniques is performed on the availability of instrumentation, excavation power and precision, potential for cost savings.

Reliability of Abundance Estimates of the Propellerclam (Cyrtodaria siliqua) Derived from Their Burrow Openings: A Case Study from Banquereau, Eastern Canada

Abstract The accuracy and reliability of abundance estimates of the infaunal propellerclam, Cyrtodaria siliqua, derived from their burrow openings was tested over a three-year period after experimental hydraulic clam dredging. Abundances of C. siliqua were obtained from hydraulic grab samples at the same locations as photographs taken to count their burrows. Correlations between abundances of clams and burrows in dredged and nondredged areas were monitored over a three-year period. All correlations between burrows and clams were positive in nondredged areas and three of six correlations were significant. There was a natural trend over time of decreasing numbers of visible burrow openings, whereas abundances of the architect of these burrows, C. siliqua, remained relatively constant. Possible explanations for this phenomenon are discussed. All postdredging correlations in the two dredging boxes were negative and nonsignificant. It is concluded that, in this habitat, counts of burrow openings in photographs...

Clamshell excavation of a permeable reactive barrier

Nowadays, permeable reactive barriers (PRB) are one of the most widespread techniques for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC in: Permeable reactive barriers: lessons learned/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive Barriers Team 2005). Although, a variety of excavation methods have been developed, backhoe excavators are often used for the construction of PRBs. The aim of this study is to describe the emplacement of a full-scale PRB and the benefits deriving from the use of a crawler crane equipped with a hydraulic grab (also known as clamshell excavator) in the excavation phases. The studied PRB was designed to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in Italy. The continuous reactive barrier was designed to be 120 m long, 13 m deep, and 0.6 m thick. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 7 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. Moreover, the adopted technique permitted a saving of bioslurry thus minimizing the amount of biocide required.

Recent invasions of alien macroinvertebrates and loss of native species in the upper Rhine River, Germany

In the summers of 2003-2005 we sampled the macroinvertebrate community of the upper Rhine River at 28 locations between kilometer 351.9 and 399.5 with a dredge and a hydraulic grab from a ship, or by hand sampling. Additionally, 16 samples were obtained from the cooling water intake screens of a thermal power plant in 2003. A total of 133 species and higher taxa were identified from approximately 140,000 organisms. A total of 33 neozoa (alien) species were identified, including the first record of Chelicorophium robustum in the Rhine River. Neozoa contributed approximately 74% to the total number of organisms collected from the ship-based samples and 85% to those from the power plant cooling water. Almost 64% of all individuals from the cooling water intake belonged to the Ponto-Caspian amphipod Dikerogammarus villosus. Similarly, only 13 taxa, four native and nine alien species, numerically dominated in the ship-based samples, representing 95% and 98% of all organisms in 2003 and 2004, respectively. The nine alien species contributed 74.7% and 72.1%, respectively, to the number of organisms. Only six species occurred abundantly in the main channel of the Rhine River, five of which were neozoa: Jaera istri, Dikerogammarus villosus, Dreissena polymorpha, Chelicorophium curvispinum, and Hypania invalida. The six abundant species colonized nearshore substrates, whereas only few species were retrieved at low densities from the bottom gravel of the central shipping lane. Species diversity was generally higher and relative abundance of neozoa was lower in backwater areas than in the main river channel. Some pronounced changes in the abundance of three numerically dominant species, including the neozoa D. polymorpha and C. curvispinum, occurred between 2003 and 2004, which likely correlated with differences in water levels and temperatures. Overall, our results demonstrate that the macroinvertebrate community of the upper Rhine River has been severely altered by the invasion of several highly successful alien species and the disappearance or population decline of native species, and that these processes are still ongoing. Changes in species composition and relative numerical abundance indicate both a displacement of native species by invasive species, and a relative rapid succession in the numerical dominance of “old“ neozoa and “new“ neozoa.

Mineralogy, chemical composition and structure of the MIR Mound, TAG Hydrothermal Field

The study of samples collected from the surface of the MIR mound (TAG Hydrothermal Field) by video‐controlled hydraulic grab allowed identification of a number of mineralogical types. These include pyrite‐chalcopyrite (Py‐Cp), bornite‐chalcopyrite‐opaline (Bn‐Cp‐Op) and sphalerite‐opaline (Sp‐Op) sulfide chimneys, massive sulfides composed of pyrite (Py), chalcopyrite‐pyrite (Cp‐Py), marcasite‐pyrite‐opaline (Mc‐Py‐Op), sphalerite‐pyrite‐opaline (Sp‐Py‐Op) and sphalerite‐chalcopyrite‐pyrite‐opaline (Sp‐Cp‐Py‐Op), as well as siliceous and Fe‐Mn oxide hydrothermal deposits. Most of the minor elements (Ag, Au, Cd, Ga, Hg, Sb and Pb) are associated with Zn‐rich massive sulfides, Co Bi, Pb, and As with Ferich ones, while Cu‐rich sulfides are depleted of trace metals. Cu‐enriched assemblages are concentrated in the northern part, Zn‐enriched in the center, and siliceous rocks in the south of the MIR mound. According to paragenetic relations, the development of the mound started with the formation of quartz (originally opaline) rocks and dendritic assemblages of melnikovite‐pyrite, followed by deposition of chalcopyrite and recrystallization of primary pyrite, subsequent generation of sphalerite‐rich assemblages and final deposition of opaline rocks. The late renewal of hydrothermal activity led to local formation of Cu‐rich chimneys enriched in Au, Ag, Hg and Pb probably due to their remobilization from inner parts of the deposit.

Initial chronology of a recently discovered hydrothermal field at 14°45′N, Mid-Atlantic Ridge

Two expeditions of the ‘Sevmorgeologija’ association (1991–1994) led to the discovery of two new hydrothermal sites on the Mid Atlantic Ridge (MAR), south of the 15°20′ North Fracture Zone, one around 14°45′N and the other around 14°42′N. The northern one, between 14°45′ and 14°45.3′N has been studied in detail. About 12 mounds have been mapped and 3 of them have been sampled using a large hydraulic grab sampler. The largest one is about 200 m long and 200 m wide. When progressively moving up on the slope of an uplifted block of the rift valley floor, the sulphide samples have revealed ages ranging from about 10 ka to 60 ka. The ages were obtained using the 230Th/234U dating method used for chronological studies of diverse hydrothermal fields. The general picture of this lateral location of the samples of different ages provides evidence of a shift in the focus of hydrothermal activity with time. Moreover, there were rejuvenation stages of hydrothermal activity, including black and white smokers.