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Terzaghi Theory Terzaghi theory is a fundamental concept in soil mechanics, which was developed by Karl Terzaghi in the 1920s. It describes the behavior of soil as a two-phase system consisting of solid particles and pore fluid and explains how the stresses and strains in soil are related to one another. The theory is based on the principles of effective stress and total stress and is used to analyze the stability and settlement of foundations, slopes, and other soil structures. Terzaghi's work laid the foundation for modern soil mechanics and geotechnical engineering. Terzaghi's theory also includes the concept of soil compressibility, which describes how soil changes volume in response to changes in stress. According to the theory, the soil will compress and lose volume when subjected to an increase in stress and will expand and gain volume when stress is reduced. This behavior is known as compression and rebound and is important in the design of foundations and other structu

Types Of Tenders Open Tender Open tendering is the main tendering procedure employed by both the government and the private sector. The Client advertises the tender offer in the local newspaper giving detail and key information of the proposed works and inviting interested contractors to tender. In the legal sense, such tender notices constitute an invitation to treat, a mere request by the employer for a suitable contractor to submit their bids or offers If the prerequisite to tendering on the form of possession of Cr the necessary registration has been identified in the tender notice, then the advertisement is directed to only that particular class of the public having the said qualifications. In order to reduce the number of inquiries, earnest money is deposited (for private projects). Until the receipt of a bone file tender is selected then it will be returned. Although the price is very important in the decision on which tender or bid to accept, it is not the only factor taken in

Tendering Process Steps  While inviting tenders following rules should be observed. Tenders are invited in regard to work contracts except when any exemption has been granted by the government. Tenders must be invited to the prescribed tender forms. Tenders must be invited in a sealed cover. In order to get more tenders wide publicity should be given. The publicity may be made through important daily newspapers, government gazette and pasting notices in public places, and sending letters to the reputed contractors and dealers. The tender notice should contain the following information: (a) Name of place and time where the contract documents can be seen and blank tender forms obtained. The cost of tender form and mode of its deposit also should be given, (b) Name of place. date and time, receipt, and opening of the tender should be given clearly, (c) The amount and mode of deposit of earnest money should be written clearly. Whether. The earnest money is to be deposited by bank draft, ca

Penetration Test  The penetration test a look at determines the hardness or softness of hydrocarbon by measuring the depth m tenths of an mm to that a regular loaded needle can penetrate vertically m 5 seconds. Sample eighteen maintained at a temperature of 25°C " The idea of a penetration take a look at is shown IN Fig one Indian normal institution has standardized the instrumentation and test procedure. Penetration Test Diagram Penetration Test Process The bitumen lS softened to a poor rm g consistency stirred thoroughly and poured into containers to a depth of at least 15 mm in excess of the expected penetration. The sample containers are then placed in a temperature-controlled water bath at a temperature of 25 degrees C for one hour. The sample with the container is taken out and the needle is arranged to make contact with the surface of the sample. The dial is set .to zero or the initial reading is taken and the needle is released for 5 seconds. The final reading is taken on

Limitations of Terzaghi Theory The value of the coefficient of consolidation has been assumed to be constant.  The distance d of the drainage path cannot be measured accurately in the field. The thickness of the deposit is generally variable, and an average value has to be estimated.  There is sometimes difficulty 1n locating the drainage face, and sometimes thin previous seams that can act as good drainage faces are missed in the boring operations. The equation is based on the assumption that the consolidation is one-dimensional. In the field, the consolidation is generally 3-dimensional. The lateral drainage may have a significant effect on the time rate of consolidation. The initial consolidation and secondary consolidation have been neglected. Sometimes these form an important part of the total consolidation. In actual practice, the pressure distribution may be far from linear or uniform.

Inverted Siphons When a main dips below the hydraulic grade line, it's referred to as associate inverted siphon. The purpose is to carry the sewer under the obstruction, such as roadway, railway, stream, river, etc. and regain as much elevation as possible. The sewage through such a pipeline (or inverted siphon) will flow under pressure which is greater than atmospheric pressure. Inverted siphons should be resorted to only where other means of passing the obstruction are not feasible, as they require considerable attention in maintenance. As the siphons are depressed below the hydraulic grade line, maintenance of self-cleansing velocity at all flows is very important. Inverted siphon Designing The construction of the siphon should be simple. The changes in direction should be easy and gradual. It is necessary to have a seIf-cleansing velocity of 1 meter per second for the minimum flow to avoid deposition in the line. The siphon should have two or three pipes of differe

Sewage Farming In India The sewage effluent can also be disposed of by applying it to the land. The percolating water may either Join the Water table or be collected below by a system of underdrains. This method can then be used for irrigating crops. And hence termed sewage farming , Since it not only disposes of the sewage but also helps in increasing crop yields (by 30% or so) as the sewage generally contains a lot of fertilizing minerals and other elements. Fertilizing elements like N, P, K, etc. do help in increasing the yield of cash crops like cotton, sugarcane, plantain, etc.  However, crops to be eaten raw or which do not have any skin to be removed before eating should not be grown on sewage farms, although this is seldom practiced by the farmers. But the sewage effluent must be treated before being used in sewage farming . In order to lay down the limiting standard for sewage effluents and the degree of treatment required, it is necessary to know all the consequences. Sewage

Comminutors Definition Comminutors or Shredders are the patented devices, which break the larger sewage solids to about 6 mm in size when the sewage is screened through them. Such a device consists of a revolving slotted drum, through which the sewage is screened (Fig.) Cutters mounted on the drum, shear the collected screenings against a comb until they are small enough to pass through 5 mm to 10 mm ‘wide slots of the drum. These are usually arranged in through 5 mm to 10 mm wide slots of the drum. These are usually arranged in pairs to facilitate repairs and maintenance.  Comminutors are of recent origin and eliminate the problem of disposal of screening, by reducing the solids to a size that can be processed elsewhere in the plant. They should always be preceded by grit chambers to prevent their excessive wear.

Settling Hello Friend Today  We Are Discuss About Settling Principle And Purpose.  Settling  is an Important topic in civil engineering The solid-liquid separation process in which a suspension is separated into two phases: Clarified supernatant leaving the top of the sedimentation tank (overflow). Concentrated sludge leaving the bottom of the sedimentation tank (underflow). purpose of Settling  To remove the coarse dispersed phase.   To remove coagulated and Hocculated impurities. To remove precipitated impurities after chemical ' treatment. To settle the sludge (biomass) after activated sludge process/tricking filters Principle of Settling Suspended solids present in water having a specific gravity greater than that of water tend to settle down by gravity as soon as turbulence is retarded by offering storage. Basin in Which the flow is retarded is called the settling tank. The theoretical average time that the water is retained within the subsidence tank i

Road Patterns The various road patterns may be classified as follows: Rectangular or block Road pattern Hexagonal Road  pattern Radial or star and block Road  pattern Radial or star and circular Road pattern Radial or star and grid Road pattern Each of these patterns has its own advantages and limitations. There can be a number of other geometric patterns also. The choice of the pattern significantly depends on the section, the layout of various cities, villages, industrial and Production centers, and on the selection of the design engineer. The rectangular or the block pattern has been adopted in the city But from the traffic Operation point this is not considered convenient roads of Chandigarh and the circular pattern is the road network of Connaught Place in New Delhi.

Drop Manhole It is a special type of manhole on a sewer line which is Constructed to provide a connection between a high-level branch sewer to a low-level main sewer. When, a branch sewer enters a manhole by, more than 0.5 to 0.6 m above the main sewer, the sewage is not allowed to fall directly into the manhole. Instead, the sewage 0f the branch sewer is brought into the manhole of the main sewer either by inclined pipe (inclined at 45°) or through a downpipe (vertical pipe). In the former case, it is known a ramp while in the latter case it is known as a drop manhole . Fig. shows details of a circular drog manhole. The branch sewer is joined to the manhole of the main sewer through a vertical pipe (or drop pipe). The sewage coming from the branch sewer flows down in the vertical pipe and emerges out through a horizontal pipe just above the benching. A plug is provided at the point where the branch sewer, if prolonged straight, intersects with the vertical wall of the manhole. The pro

Stopping Sight Distance The minimum sight distance offered on a road at any spot ought to be of enough length to prevent a vehicle from traveling at style speed, safely while not a collision with the other obstruction. absolutely the minimum sight distance is adequate for the stopping sight distance , which is additionally sometimes referred to as non-passing sight distance. The sight distance available on a road to a driver at any instance depends on : (i) features of the road ahead. (ii) height of the driver‘s eye above the road surface. (iii) height of the object above the road surface. The feature of the road ahead which affect the sight distance is the horizontal alignment and vertical profile of the road, the traffic condition, and the position of obstructions. At vertical summit curves, the height of the driver‘s eye and the object above road level are more important factors affecting visibility. The height of an object to be considered for stopping a vehicle depends on what mig

Muller-Breslau principle Muller-Breslau principle is the most essential tool in obtaining influence lines for statically determinate us well u statically indeterminate structures. The method is based on the concept of the influence line as a deflection curve. The Muller-Breslau principle may be stated as follows. If an internal stress component or a reaction component is considered to act through some small distance and thereby deflect or displace a structure, the curve of 1 the deflected or displaced structure will be, to some scale, the influence line for the stressor reaction component. Muller-Breslau principle is applicable  1. Statically determinate beams 2. Statically indeterminate beams The Muller-Breslau principle influence theorem for ‘ statically determinate beams may be stated as follows: The influence line for an assigned function of a statically determinate beam may be obtained by removing ‘ the restraint offered by that function and introducing a directly related gener

Highway Pavements This Topic Highway Pavements From Highway Engineering And Civil Engineering. The surface of the road ought to be stable and non-yielding, to permit the serious wheel lot of road traffic to maneuver with the least doable rolling resistance. The paved surface ought to even be even on the longitudinal profile to alter the quick vehicles to maneuver safely and well at the look speed.  At high moisture content, the soil becomes weaker and soft and starts yielding under heavy wheel loads, thus increasing the resistance to traction. The earth road may not be able to fulfill any of the above requirements, especially during the varying conditions of traffic and weather changes. Therefore a pavement consisting of superior and stronger materials is laid over the prepared earth surface which could fulfill the above requirements. The objective of laying a pavement is to support the wheel loads and to transfer the load stresses through a wider area on the soil subgrade below. Thus

Trickling Filter Process In trickling filter, sewage is allowed to sprinkle or trickle over a bed of course, rough, hard filter media and it is then collected through the under drainage system. Spray nozzles or rotary distributors are used for this purpose. The biological purification is brought about mainly by aerobic bacteria which form a bacterial film, known as biofilm, around the particles of the filtering media,Though, trickling filter is classified as ah aerobic treatment device, the microbial film the slime layer formed on the 111ter medium is aerobic to a depth of only 0 1 to 0.2 mm and the remaining part of the 111m 18 anaerobic. As the wastewater flows over the microbial film, the soluble organic material in the sewage is rapidly metabolized while the colloidal organics are adsorbed onto the surface. In the outer portions of the biological film, the organic matter is degraded by aerobic microorganisms. Since the concentration is higher at the outer ' layer, the micro-o

Working Of Septic Tank In the grit chamber, sand, grit, settleable inorganic matter, etc. settle before sewage enters the anaerobic chamber. In the anaerobic chamber, organic solids settle at the bottom of the tank where anaerobic bacteria act on it and convert complex unstable compounds into simple stable compounds.  Nitrogen is converted into ammonia and the mixture becomes alkaline. The colloidal matter is flocculated and then liquefied and finally digested. Discharged organic matters are also digested.  Due to these processes, there is a considerable reduction in the volume of sludge and it settles at the bottom of the tank. The clarified sewage discharges through the outlet.  Cases are liberated due to sludge digestion which rises to the surface constantly in the form of bubbles. These bubbles carry small particles of decomposed sludge and a floating layer of scum (black in color) is formed on the surface.  The scum contains anaerobic bacteria that attacks the undissolved componen

Fixed-Bed Biofilm Activated Sludge The FBAS is  Called Fixed-Bed Biofilm Activated Sludge.  The FBAS process is essentially an activated sludge-attached growth process where the plant roots provide the area for the biofilm to develop and grow. The aeration system is divided into a series of biological reactors where fixed biofilm is maintained in every stage of the process.  As the influent travels through the cascade, the available nutrient quantity is consumed and as a result, the composition of the ecosystem fixed in the biofilm changes from reactor to reactor, gradually adapting itself to the decreasing nutrient concentration. In each cascade stage, a specially adapted ecosystem will form, thus maximizing the decomposition of contaminants. As reported, some plants with such technologies have been set up in different countries including Hungary, China, France, etc in the last 10 years. However, it will be useful to demonstrate this project under Indian conditions. Fixed-Bed Biofil

Prefabrication Prefabrication is the practice of assembling components of a structure in a factory or another manufacturing site and transporting complete assemblies or sub-assemblies to the construction site where the structure is to be located. The term is used to distinguish this process from the more conventional construction practice of transporting the basic materials to the construction site where all assembly is carried out. The term prefabrication also applies to the manufacturing of things other than structures at a fixed site. It is frequently used when the fabrication of a section of a machine or any movable structure is shifted from the main manufacturing site to another location, and the section is supplied assembled and ready to fit.  It is not generally used to refer to electrical or electronic components of a machine, or mechanical parts such as pumps, gearboxes, and compressors which are usually supplied as separate items, but to sections of the body of the machine t