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Showing 7 results for Grouting

M. Heidarzadeh, A.a. Mirghasemi, S. Etemadzadeh,
Volume 5, Issue 1 (3-2007)
Abstract

A new chemical grouting method has been developed for conglomerate formations based on the experimental studies. Due to the lack of chemical grouting experience of conglomerate formations, the testing programs were performed to evaluate the performance of chemical grouting in the water sealing of part of conglomerate foundation of Karkheh earth dam using a combination of field and laboratory tests. First, the chemical grouts alone were examined with regard to viscosity-time behavior, gelation time, temperature-influence, stability, and deformability. These laboratory tests, led to the selection of the final chemical grout which was a solution of sodium silicate, water, and ethyl acetate as reactant. The second step tested grout-soil interaction: The injectability and permeability reduction of the selected chemical grout was examined in field injection tests. In this step two field tests were performed including shallow test holes without hydrostatic pressure and full scale tests under dam real hydrostatic pressure head. Based on these two field injection tests, performed in the conglomerate foundation of Karkheh dam, a new chemical grouting method for conglomerate formations is proposed and satisfactory results led to the recommendation of this method for eventually successful application.
T. Dahlberg,
Volume 8, Issue 1 (3-2010)
Abstract

The track stiffness experienced by a train will vary along the track. Sometimes the stiffness variation may be

very large within a short distance. One example is when an unsupported sleeper is hanging in the rail. Track stiffness

is then, locally at that sleeper, very low. At insulated joints the bending stiffness of the rail has a discontinuity implying

a discontinuity also of the track stiffness. A third example of an abrupt change of track stiffness is the transition from

an embankment to a bridge. At switches both mass and stiffness change rapidly. The variations of track stiffness will

induce variations in the wheel/rail contact force. This will intensify track degradation such as increased wear, fatigue,

track settlement due to permanent deformation of the ballast and the substructure, and so on. As soon as the track

geometry starts to deteriorate, the variations of the wheel/rail interaction forces will increase, and the track

deterioration rate increases. In the work reported here the possibility to smooth out track stiffness variations is

discussed. It is demonstrated that by modifying the stiffness variations along the track, for example by use of grouting

or under-sleeper pads, the variations of the wheel/rail contact force may be considerably reduced.


M. Hassanlourad, H. Salehzadeh, H. Shahnazari,
Volume 9, Issue 4 (12-2011)
Abstract

The effects of cementation and the physical properties of grains on the shear behavior of grouted sands are investigated in this

paper. The consolidated-undrained triaxial shear behavior of three grouted carbonate sands with different physical properties,

including particle size distribution, particle shape and void ratio, was studied. Two sands were obtained from the north shores

of the Persian Gulf, south of Iran, called Hormoz and Kish islands sands, and one sand was obtained from the south beaches

of England and called Rock beach sand. The selected sands were grouted using a chemical grout of sodium silicate and tested

after one month of curing. Test results showed that the effect of bonding on the shear behavior and strength depends on the bond

strength and confining pressure. In addition, the shear behavior, yield strength and shear strength of grouted sands under

constant conditions, including the initial relative density, bonds strength, confining pressure and loading, were affected by the

physical properties of the sands. Furthermore, the parameters of the Mohr-Coulomb shear strength failure envelope, including

the cohesion and internal friction angle of grouted sands under constant conditions, were affected by the physical properties

and structure of the soils.


M. Heidarzadeh, A.a. Mirghasemi, S. M. Sadr Lahijani, F. Eslamian,
Volume 11, Issue 1 (5-2013)
Abstract

In a rare engineering experience throughout the world, we successfully stabilized relatively coarse materials of drain using

cement grouting. The grouting work was performed at the Karkheh earth dam, southwest Iran, and was part of the efforts to

extend the dam’s cut-off wall. Since the dam was completed, the execution of the new cut-off wall from the dam crest was

inevitable. Hence, one of the main difficulties associated with the development of the new cut-off wall was trenching and execution

of plastic-concrete wall through the relatively coarse materials of drain in the dam body. Due to high permeability of drain, the

work was associated with the possible risk of excessive slurry loss which could result in the collapse of the trench. In order to

achieve an appropriate grouting plan and to determine the mix ratio for the grouting material, a full-scale test platform consisting

of actual drain materials was constructed and underwent various tests. Results of the testing program revealed that a grouting

plan with at least 2 grouting rows and a Water/Cement mix ratio of 1/ (1.5-2) can successfully stabilize the drain materials. After

finalizing the technical characteristics of the grouting work, the method was applied on the drain materials of the Karkheh dam

body. The results were satisfactory and the drain materials were stabilized successfully so that the cut-off wall was executed

without any technical problem.


Zh. Zhang, J. Xu,
Volume 11, Issue 1 (3-2013)
Abstract

To improve the construction efficiency of the Longtan Hydropower Project, this paper studies the multi-mode resourceconstrained project scheduling problem in its Drilling Grouting Construction Project. A multiple objective decision making model with bi-random coefficients is first proposed for this practical problem to cope with hybrid uncertain environment where twofold randomness exists. Subsequently, to deal with the uncertainties, the chance constraint operator is introduced and the equivalent crisp model is derived. Furthermore, the particular nature of our model motivates us to develop particle swarm ptimization algorithm for the equivalent crisp model. Finally, the results generated by computer highlight the performances of the proposed model and algorithm in solving large-scale practical problems.
M. Heidarzadeh, A. A. Mirghasemi, H. Niroomand,
Volume 13, Issue 1 (3-2015)
Abstract

We report engineering experiences from the critical task of relief well installation under high artesian flow conditions at the downstream toe of the Karkheh earth dam, Iran. Due to the establishment of excessive uplift pressure at the downstream toe of the Karkheh dam, installation of a series of new relief wells was considered to permanently relieve part of these pressures. The mentioned uplift pressure, as high as around 30 m above the ground level, was produced in a confined conglomerate aquifer bounded above and below by relatively impervious mudstone layers which reduced the safety factor of the dam toe to below 1.0. Investigations on the shortcomings of the old relief wells installed at the dam site showed that the main problems were: insufficient well numbers, insufficient well diameters, irregular well screens causing their blockage by time passing, and insufficient total opening area. Despite engineering difficulties and associated risk of downstream toe instability, installation of new relief wells was successfully completed under high artesian flow conditions” was successfully completed. The employed technique for the construction of the new relief wells under flowing artesian conditions was based on: 1) cement grouting and casing of the well, 2) telescopic drilling, 3) application of appropriate drilling fluid, and 4) controlling the artesian flow by adding a long vertical pipe to the top of the relief wells. Numerical modeling of seepage for the Karkheh dam foundation showed that, as a result of the installation of the new relief wells, the safety factor of the downstream toe increased to the safe value of 1.3 for the normal reservoir water level.

Volume 15, Issue 6 (9-2017)
Abstract

It is vital to control the settlement of ultra-high voltage and long span tower foundation because of the difficult construction and strict deformation control. Based on the thinking of deformation compatibility, the mechanical model of deformation compatibility between pile and soil is established. Relying on the long span tower project Lingzhou–Shaoxing ±800 kV DC transmission lines across the Yangtze River, through checking ultimate bearing capacity of existing pile foundation, it can be obtained that the present design foundation can effectively meet the upper 200–220 t load, but it cannot meet the load requirements about 300 t in the construction. The failures of tower foundation mainly display that piles cut into the soil with penetration type in the early condition. With the load increasing, the shallow soil and infrastructure gradually damage with the whole cap sinking, cushion layer destruction and the surrounding soil uplifting. As a result, tower foundation is unable to withstand the effect of upper overload and the whole tower becomes shear failure. The treatment scheme was proposed that it can improve the cushion thickness and strength combined with grouting consolidation to soil around the piles. Thus, the stability of tower foundation improves significantly and settlement was controlled within the permitted range of below 10 mm, which can meet the structure requirements. The results of numerical simulation based on deformation compatibility between pile and soil coincide well with field measured results.



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