The purpose of this experiment was to explicate how to utilize two type of oedometer to cipher compaction index ( Cc ) and re-compression index ( Cr ) . mensurating the pre-consilidation ( s’vc ) . and to foretell the coefficient of consolidation ( Cv ) . The dirt used in this experiment is Kaolinite clay. which has Cv = 8. 69 sqm/year at 300 kPa ( hydraulic consequence ) and Cv = 2. 98 sqm/year at 288 kPa ( manual consequence ) . This consequence so would be compare with some theoretical computation by utilizing the isochorne secret plan.
Introduction
Oedometer trial is test to show and mensurate the consolidation of a dirt. Consolidation is a procedure when an external burden is given at the top of a saturated dirt which will do the H2O to be squeezed from the dirt and eventually will take to the colony procedure. This long procedure is non every bit simple as it looks. nevertheless it may take several old ages for the dirt until the concluding colony is reached. In this instance oedometer will be used to excite the existent consolidation state of affairs procedure of the site. This study will explicate how oedometer plants. how to treat oedometer consequence for farther computation. and explicate the difference between two types of oedometer that are operated in the experiment. Experiment Description
Two type of oedometer were used in this experiment. They were manual oedometer and hydraulic oedometer. The sample that was used was Kalinite clay. A 34. 2 mm diameter of ring was used to set the sample during the experiment. Each experiment was done individually because all the method and the technique were different.
Manual Oedometer
Two sets of informations were collected at the same clip. The first informations were obtained by using force per unit area to pack the clay. This was done by added or
removed a burden every 25 proceedingss and step the gage deepness from the dial gage. The compression and the recovery of the dirt will take clip to absolutely happen. However. it is assumed that in 25 proceedingss. 95 % will happen. At the terminal of the experiment. a set of informations would be used to plot the nothingness ratio versus perpendicular emphasis graph. This secret plan so used to cipher the Cv and Cc value which were obtained by ciphering the incline of each curve. Beside. pre- consolidation emphasis could besides be obtained by using the Cassagrande’s Method.
The 2nd set of informations were collected from at the first 25 proceedingss of the old experiment. It worked by using a fix sum of force per unit area ( 288kPa ) and mensurate the deepness of the dial gage at 10s. 20s. 30s. 1min. 1. 5min. 2min. 3min. 4min. 6min. 9min. 12min. 16min. and 25min. This set of informations the would be used to make a secret plan of colony V square root of clip. Then. this graph would be used to cipher the coefficient of consolidation ( Cv ) at 90 % of primary consolidation.
Hydraulic Oedometer
Initially. hydraulic oedometer was set with 250 kPa of applied force per unit area. 202 kPa of pore force per unit area. and 200 kPa of back force per unit area. The sample thickness was 20 millimeter. with 75. 4 mm ring diameter and volume of 45149 mm3. The hydraulic oedometer consist of two end products. the volume and the back force per unit area. The volume was obtained from the digital show while the back force per unit area was read from the multimeter.
These two types of information were so colleted for every selected interval of colony clip. After the experiment was finished. the applied force per unit area was increased to 300 kPa. Then. the collected informations created a secret plan of colony V square root of clip which recently was used to mensurate the coefficient of consolidation at 90 % of primary consolidation. Besides. this secret plan was used to performhe fluctuation of pore force per unit area vs clip. which so determined the theoretical fluctuation of the pore force per unit area by utilizing the isochrones secret plan.
