Abdur Razzaque at Department of Civil Engineering, Khulna University of Engineering and Technology, Khulna, Bangladesh. Abdur Razzaque entitled "Study on Selection of Suitable Foundation for Khulna City Corporation Area" has been approved by the board of examiners in partial fulfillment of the requirements for the degree of Master of Engineering in the Department of Civil Engineering, Khulna University of Engineering & Technology, Khulna, Bangladesh in November 2006. We also thank all the laboratory technicians of Department of Civil Engineering, KUET, for their kind help in field and laboratory tests during the works of this project.
Since exploration of the subsoil is expensive and time-consuming, an evaluation of the condition of the subsoil in a comprehensive way can help the designer in this context to select a suitable foundation for the KCC area. Comparison of qu between calculated and laboratory test result Borehole location (for qu result) at KCC. Cc from Calculated and laboratory test result Location of Borehole for Cc at KCC.
Profile q, in the KCC area through section X 1-X2 at a depth of 5 feet 92 Profile q, in the KCC area through the section X I-X2 at a depth of IO feet 92 Profile qu in the KCC area through the section Y I-Y2 at a depth of 5 feet 93 KCC area qu profile through section Y I-Y2 at a depth of IO feet 93 KCC area qu profile through section Z 1-Z2 at a depth of 5 feet 94 KCC area qu profile through section Z I -Z2 at a depth of IO feet 94 Average Cc from correlation equation and existing soil report I 08 Borehole location (auger drilling and existing report) in KCC area I 09 for Cc. Profile Cc in KCC area through section X I-X2 at a depth of 5 feet 110 Profile of Cc al KCC area through section X l-X2 at a depth of IO feet 110 Profile of Cc al KCC area through section Y l-Y2 at a depth of 5 feet I 11 Profile Cc in the KCC area through section YI - Y2 at a depth of IO feet 111 Profile of Cc in the KCC area through the section Z I -Z2 at a depth of 5 feet I 12 Profile of Cc in the KCC area through the section Z 1-Z2 at a depth of IO feet 112 Well location (drilling and existing report) in the KCC 115 area for the peat layer.
INTRODUCTION
In the upper horizons, the subsoil of the vast area of Bangladesh consists of very soft, fine-grained soil deposits of recent origin. During geological changes in the past, part of the Sundarbans was submerged with weathered and sedimented sediments, resulting in the present peal deposits in these regions. Choice or different location of Khulna city corporation area from Labonchora to KU ET campus.
For this rapid development, infrastructures are being constructed or will be constructed in and around the Khulna City Corporation area. Preparation of profile for peat. immediate observation of the water level. XV) Proposed suitable foundation or Khulna City Corporation area. I Jc constructed two preliminary mean soil profiles from north to south and east to west of Khulna city.
The City Corporation or Khulna area contains deposits of line-grained soil covered by a layer of crust or varying thickness".
LITERATURE REVIEW
The filling of this part of the basin with sediments was largely controlled by the northern transgression. The surface physiography of the KCC is not perfectly planar and can be characterized by six major gcornorphic units (Fig. 2.1). A detailed study of the lithostratigraphy of Khulna city and its region can give an accurate idea of its direction.
Under certain conditions, the decomposition of the latter is inhibited in the absence of oxygen, and archeology often benefits from this. Soundings can be taken at the bottom of the hole or samples can be used to take samples below the bottom of the hole. Flush drilling is used to form an open hole in the ground so that soil samples or rock borings can be taken at the bottom of the hole.
The progress of the hole is accomplished by alternately raising and dropping a heavy drill bit which is attached to the lower end of a drill stem. The borehole is usually kept dry except for a small amount of water that is added to form a cuttings slurry. The Tcrzaghi analysis makes the following assumptions to arrive at an approximate value of bearing capacity.
The water content of a soil sample is the ratio of water in the sample to its dry weight.
LABRORATORY INVESTIGATION
I 05°-110°C. 24 hours) and the moisture content is calculated by comparing the weight loss of the sample with its dry weight. A groove is cut through the sample along the symmetrical axis of the cup, preferably in one pass, using a standard grooving tool. The liquid limit is the water content at which the soil is sufficiently liquid when the device is hit 25 times.
A graph is made between the water content as an ordinate and the number of beats on a log scale as an abscissa. The liquid limit The liquid limit is the minimum moisture content at which the soil changes from liquid musty to plastic shale. The plastic limit is the minimum water content at which a soil is simply plastic and is determined by rolling out a soil sample at a slowly decreasing water content until the desired water content is reached at which a 1/8 inch diameter wire is just begging to crumble.
The specific gravity of a solid, defined as the ratio of the weight of a unit of solid in air to the weight or water. Take about 10 g of plastic soil in one hand and form a ball. If the diameter of the thread becomes less than 3 mm, without the formation of cracks, this indicates that the water content is greater than the plasticity limit.
The water content at which the soil can be rolled into a thread approximately 3 mm in diameter without crumbling is known as the plastic limit. The plastic limit is the minimum moisture content below which the soil ceases to behave as a plastic material. To determine the plastic limit of a soil, it is air-dried and sieved through a 425 ~l lS sieve.
The sample is then placed on the horizontal pedestal of the unconfined compression apparatus in a vertical position. The load is applied axially to the top of the specimen and distributed uniformly over the surface of the specimen by means of a double-supplying ring assembly equipped with a strain gauge, equipped with apparatus. The load is applied at such a rate that the vertical deformation of the sample is almost 2% per second. minute to avoid and drain under compression.
RESULTS AND DISCUSSION
The Cc values obtained using this formula in the test results of existing soil reports (210 No. Three maps have been prepared showing the spatial distribution of peat layers as or where it is present in the above 3 levels shown in Fig. Although the Cc data were not sufficient in number to draw conclusions on the basis of homogeneous distribution for the entire OEK area, these profiles were made.
The auger Cc values obtained in Table 5.6 are compared with the Cc values obtained from the correlation equation, together with the actual minimum Cc result. Therefore, the use of Cc obtained indirectly from drill samples can be a reasonable basis for the Cc profile. The investigation reveals that from 0 to 10 feet from the existing ground surface the subsoil is mainly composed of cohesive soils (clay or clay with traces of silt) of soft to medium consistency with an occasional layer of peat, and below this layer the subsoil is mainly composed of very fine sand and/or silty clay.
Removal of peat from trench below IO feet will cause practical inconvenience to Khulna due to water table and/or soft soil. When peat is not found within 20 feet (detectable by auger drilling), q, and Cc obtained from correlation equations can be used to design the foundation, which can be laid within normal depth of 3 to 5 feet for building 2-3 stories with an average room size. In this underground state, normal habitation even up to 2-3 floors should not have a foundation (load-bearing wall I column beam) laid over the peat layer.
The soil up to the bottom of the peat layer should be removed inside the trench and the additional void filled with sand and compacted to the required compaction before the foundation is laid. Extension of this borehole study to the entire KKK area in relation to the well-defined location. Regardless of the presence of a peat foundation, the use of bored piles is a common example if there are suitable layers.
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