Picture 3. Scheme of the differential settlement of the structure due to the foundation soil liquefaction. Picture 4. The consequences of liquefaction after the earthquake in Christchurch New Zealand , In order to estimate the occurrence of liquefaction at a location during a strong earthquake, it is necessary to investigate the location and make a geotechnical report that should contain the following data:.
Prevention of consequences of liquefaction on existing structures can be executed in several ways:. The most common way of preventing the occurrence of liquefaction are foundation soil improvement methods. But earthquake insurance from a CEA participating residential insurer is available to help you recover financially from earthquake liquefaction damage. Insure Your Dwelling.
Phone: The components of this Methodology, as briefly summarized below, were developed to provide a rational treatment of the various factors that affect penetration resistance and cyclic resistance.
The cyclic resistance ratio represents the liquefaction resistance of the soil, expressed as CRR. That means cyclic stress required to induce liquefaction for a soil stratum. The magnitude scaling factor MSF is used to account for duration effects i. The MSF relationship was derived by combing. Seismic ground acceleration plays an important role in assessing effects of earthquakes on the built environment, persons, and the natural environment.
Earthquake shaking generally occurs in all three directions. Therefore, PGA is often split into the horizontal and vertical components. In present study peak ground acceleration is calculated using a computer based program, LiqIT. LiqIT is designed to provide an intuitive interface that simplifies and speeds the process of performing and interpreting the results of ground response analyses.
The program is organized into three managers — an Input data Mnager, a Solution , and an Output data Manager — and a Report. In the normal sequence of operations, the user will move from the Input data to the Solution Manager and then on to the Output data, as indicated graphically below.
The Input Data Manager allows all input data to be entered, checked, and saved prior to program execution. The Input data.
Manager provides a series of forms on which the required data can be entered, and on which the desired output can be specified. Input data manager consists of soil profile, input motions and report. LiqIT allows you to view a variety of potential input motions and select the ones that are most appropriate for the analysis. The Solution Manager performs the actual ground response analysis. It requires that the user specify a valid input data file with the data extension and then performs the required that allows the user to track the progress of the analysis.
Upon completion of the analysis, the Solution Manager saves he results in a file. The Output data Manager allows the user to generate a wide range of plots of the results of the analysis. It requires that the user specify a valid output data file, and then provides a number of forms for plotting time histories, spectra, variations of parameters with depth, and for computation of scalar parameters.
The Output data Manager also allows the user to view an animation of the horizontal displacements throughout the soil profile- many users find this feature very helpful for developing an intuitive understanding of the response of the soil profile.
The Report produced by a word processor that is built into LiqIT. The Report allows the user to keep a record of each analysis. All input data is automatically written to the Report and updated when the Report is accessed. Many users find the Report useful for internal documentation of their analyses and for preparation of project reports for their clients. The below mentioned required data values are got through consultancy companies. LiqIT Software consists of:. In present study N-values obtained from 20 locations at different depths are considered for assessment of liquefaction potential of soil.
The Soil has been analyzed for peak ground acceleration levels obtained from LiqIT and Factor of safety is calculated by using Idriss method. Liquefaction susceptibility through LiqIT software By calculating the factor of safety using the Idriss method, using the parameters, peak ground acceleration and SPT N values the susceptibility of liquefaction is measured along the borehole depth. Susceptibility of liquefaction is measured along the depths of 2, 6, 10, up to 20m for 20 locations.
A newer method is vibroflotation , which is proving to be an effective prevention. Technicians insert vibrating probes into the soil at deep levels, and the trembling shakes the loose soil.
The compression of the loose soil particles lessens the number of air pockets where water can settle. Another new method includes injecting the soil with stabilizing materials. Expert geologists and geotechnical engineers are studying the effectiveness of this process. If you would like more information on this technique, the City of Boston has an article describing the process in depth. Soil liquefaction is a global problem.
Expert geologists and geotechnical engineers are seeking environmentally safe ways to prevent loss of property and life when liquefaction occurs.
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