| Summary, etc |
The October 15, 2013 7.2-magnitude earthquake in Cebu and Bohol resulted in multiple reports of occurrences of liquefaction. This prompted the researchers to engage in the study entitled ?A Study on the Common Properties of Soil Usually Subjected to Liquefaction in Metro Cebu as a Basis for Recommendation.?<br/>This study aimed to determine the similarities in soil properties in areas with confirmed cases of liquefaction in terms of soil grain properties, aggregate soil properties and soil classification. The researchers have used the Modified Chinese Criteria for assessing soil liquefaction as basis for the study. Based on the Modified Chinese Criteria, soils are considered to be susceptible to liquefaction if (1) contains less than fifteen percent (15%) of clay fraction (finer than 0.0002mm); (2) liquid limit (LL) less than thirty-two percent (32%) (3) Water content (WC) greater than or equal to ninety percent (90%) of liquid limit.<br/>Experimental method of research was used in this study. The study was composed of two parts. The first part of the study involved the testing of samples for its liquefaction potential as defined by the Modified Chinese Criteria. The second part of the study involved the researchers designing a prototype device with which to test the soil sample for liquefaction.<br/>The researchers have identified three locations in Metro Cebu with confirmed occurrences of liquefaction. The three locations were the following: (1) Cebu International Port, North Reclamation Area, Cebu City; (2) Mandaue Slaughterhouse, Paknaan, Mandaue City,Cebu; and (3) Mandaue City Jail, Buagsong, Mandaue City, Cebu. All three locations are reclaimed areas.<br/>The samples were collected using Test Pit Method. The soil samples were subjected to Grain Size Analysis including Hydrometer Test, Liquid Limit Determination, Plastic Limit Determination, Laboratory Compaction Test and In-place Density Test was also performed on the locations. A prototype liquefaction device (as shown in Appendix 7) was developed by the researchers to test the soil samples for liquefaction.<br/>The soil samples have shown zero or small plastic limit. A soil has zero plastic limit when it is cohesionless therefore cohesionless soils have the most potential to liquefy. Another factor is its location. All three sites are reclaimed area and are prone to liquefaction due to its topography and soil properties. The film materials used are often substandard.<br/>Forsoil to liquefy, three conditions must be present. First, it should have low relative compaction. Second, high water table or at least, must contain enough water content equal or higher than its liquid limit. In all sites, ground water table could be found at 0.4 to 0.6 meters below the natural grade line. Third, it must have a high percentage of cohensionless soils. The soil in the three sites is composed mainly of sand.<br/>The researchers recommend that study be done in more locations including those outside of Cebu. Also, the researchers recommend that further studies be made based on this research to include the soil?s permeability. After identifying the properties of soil usually subjected to liquefaction, it is important to find ways on how to mitigate liquefaction to ensure the stability of structures. As what was mentioned above, three factors must be present for soil to liquefy. The researchers recommend that for structures that will be built on high-risk areas (e.g. reclaimed areas), floating foundation, isolating the soil using piles, and mat foundation should be considered in the design of the structure. The model should also be improved. It is highly recommended that the liquefaction device be ran by a machine to acquire more accurate results. |