Foundations and Earthworks Problems

Task 1

SCENARIO 1

a)There are four types of foundation loads as follow: Firstly, live loads. Live loads is produced by the users of a home. Example, people, furniture, storage items. The affects of the load is exert force on almost all of a house’s. To design floor systems that limit deflection & vibration. Secondly, dead load. That means, forces incurred due to the weight of all the materials used in construction of a home. For examples, roof, ceiling, floor, wall & partition. The affects of the this load is a constant over the life of the structure. Big impacts on the long-term deflection/creep of framing members. Thirdly, wind load. Positives or negatives pressures exerted on a house when it obstructs the flow of moving air. The affects of wind load is depends on : location, height, and roof pitch. Fourthly, seismic load. Seismic load that means the inertial forces acting on a house due to earthquake-induced ground motions. The affects of seismic load all components of a frame and shear-resisting elements are most affected.

b)The two types of foundation are as follows:

i)Pad foundation

Pad foundation is normally used as foundation to building or residential building not exceeding four storeys on stiff soil such as gravel. Most of the said buildings are framed structure. The pad foundation is built if the load supported by the column is small. A pad foundation is the base of a column. The size of pad foundation depends on the size of load to be carried and load bearing capacity of the soil. The pad foundation is not suitable for large and high-rise building because it needs to carry high load, which is not practical and uneconomical.

Pad foundation

ii)Raft foundation

Raft foundation are used to spread the load of the superstructure over a large base to reduce the load per unit one being imposed on ground and this is particularly useful where low bearing capacity soil are encountered and where individual column load are heavy. This types of slab is known as the foundation. Raft foundation can be constructed as follows:

a)solid slab raft foundation

Solid slab raft foundation is constructed at the entire base of the planned building. The thickness of slab depends on applied load and strength of soil at the site.

b)beam and slab raft foundation

Beam and slab raft foundation is required when thickness of the designed solid slab raft foundation exceeds 300 mm. The reinforced concrete slab is constructed on the ground whereas the beams are constructed on the slab at specific locations.

c)cellular in raft foundation

Cellular raft foundation is establishment is built on detached soil and on soil that operation to settle uncalled for case in point unmoving mining site. In such condition, the thickness of the constructed slab may exceed 1 meter, therefore the construction of cellular raft foundation is preferable.

Task 2

a)The effect of water and chemicals in the soils are there is either too much water, causing the soil to swell, or not enough, or not enough, causing the soil to shrink. If all soil beneath a foundation swells uniformly or shrinks uniformly it is unlikely to cause cracks and other damage. Most differential movement is caused by differences in soil moisture. After construction, soil moisture. After construction, soil beneath part of foundation becomes wetter or drier than the rest of the soil. The chemical can seep is contaminated with toxic materials. These toxic materials can seep into ground and eventually contaminated the water. Therefore, it is important to conserve the ground water resource so that surfaces it can be used as an alternative resource in the event that surface water is contaminated or dried during dry seasons. The treatment can be done to avoid foundation failure is the treatment process depends on properties of raw water and this properties of water can be divided into three categories; physical, chemical and biological properties. The properties of raw water depend on impurities in it. Impurities in water can be categorized into macro and micro impurities. Macro impurities are debris such as garbage, twigs, leaves and others. Micro impurities are very fine and cannot be seen by eyes.

b)The effect of subsoil movement there are different constrains that cause the development of soil and rock. Furthermore that, gravity is a significant drives that draw rock parts down inclines in occasions called mass developments. Likewise, mass developments fluctuate in their rate, force, and section size. Besides, when mass developments happens quickly, they have a tendency to be the most ruinous and emotional. In this manner, rock falls happen when rock parts tumble from soak precipices. This is the speediest kind of mass developments. Along these lines, the pieces may be as small as stones or as enormous as titan rocks. Avalanches happen when a lot of detached rock joined with soil fall abruptly down an incline. Finally, The steepness of the slant may influences the sum and the span of the rock material in the avalanches. Bigger avalanches have a tendency to happen on steeper inclines and include bigger squares of bedrock.

Task 3

a)The importance of underpinning work are to transfer the load carried by an existing foundation from its presents bearing level to a new level at a lower depth. Beside that, to replace an existing weak foundation. In construction, underpinning is the process of strengthening and stabilizing the foundation of an existing building or other structure. The reason for underpinning are as follows: the original foundation is simply not strong or stable enough. The usage of the structure has changed. The properties of soil supporting the foundation may have changed (possibly through subsidence) or were mischaracterized during design. The construction of nearby structures necessitates the excavation of soil supporting existing foundations. It is more economical, due to land price or otherwise, to work on the present structure’s foundation than to build a new one.

b)The precaution steps before underpinning works are as follow before impleting suitable underpinning measures the accompanying vital focuses ought to be precisely went to : Firstly, the existing structure ought to be completely inspected painstakingly and proper underpinning strategy ought to be embraced. Besides, all poor stone work, for example, joints, breaks, putting ought to be amended in the recent past. Thirdly, fundamental shoring and struting ought to be carried out such that current structure is sheltered. Forward, Urgent repair like grouting of splits, insertion of pole between dividers. Other than, ought to be completed before beginning underpinning. Fifth, satisfactory consideration ought to be taken to guarantee that there ought to be no development of structure for which levels ought to be stamped. Sixth, underpinning procedure is not a science yet a symbolization ought to be practiced relying upon the circumstances.

Underpinning works

Task 4

a)

i)Trench excavation

Trench excavation in development industry is something that specialists ought to be prepared on keeping in mind the end goal to avoid disaster. So as to work securely in the region of trenches or unearthings managements and workers need to character perils connected with trenching and unearthing work, evaluate hazard and dispose of or minimize those danger in the recent past, throughout and after the execution of work. Trenches and unearthings

greatest danger is the likelihood of breakdown because of precariousness. Before starting work in a trench, unearthing or limited space on a development site laborers ought to perform an audit to figure out if it is completely important to work in the trench/exhuming, bound space.

Trench excavation

ii)Basement excavation

A basement excavation is a development burrow performed for the mean of unpredictable out a cellar. There are a few settings in which storm cellar uncovering may be performed. This procedure is usually supervised by an experienced contractor or a basement excavation company, because it can be complicated in addition to labor intensive. While it is possible to excavate by hand, there are some serious risks which must be carefully evaluated before taking the plunge. Besides that, the best time to do a basement excavation is when a home site is being prepared. In this case, the site is already being excavated in preparation for laying the foundations. Therefore, if people want a basement, the depth of the excavation can be deepened to rough out the basement so that the basement and foundations can be form at the same time. Thus, this can be a way to add room to a structure without adding height, and some people leave the basement unfinished to cut costs while protect that they will have that space accessible at a later time if they need it. This basement was built to the same footprint as the house above, which in turn was the footprint of the pair of semis that had been there before, plus a room at the back.

The planning permission limited the basement to a railway carriage-shape down the middle so the client said he would block off what he didn’t have permission for to put it out of use. (No talking in the ranks, the cynical amongst you should believe that he did so). The area at this endwas for a stairwell. The area at the far end for a window well.

Basement excavation

b)With the aid of sketches, explain the excavation support systems.

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