Papers by Author: Zhao Yan Li

Abstract: Based on survey of the Bachu-Jiashi earthquake liquefaction sites, much new basic liquefaction information were obtained and China’s liquefaction database was enriched. A detailed investigation of the Bachu earthquake liquefaction site was conducted, in which three kinds of in situ test measures were used to obtain the site information, and given China mainland SPT data of liquefaction site increase by 40%. By site investigation, international standard liquefaction site CPT data were obtained, and also, the first measurement of liquefaction site data by SPT and CPT index was conducted. With the new data, the feasibility of liquefaction discrimination methods of China was inspected.

Abstract: Through the Bachu-Jiashi Ms6.8 earthquake liquefaction investigation and test, obtain the 47 the standard penetration test date, examine the existing standard applicability based on standard penetration test of soil liquefaction identification method, and put forward the new sandy soil liquefaction evaluation formula. Analysis shows that the current assessment formula base on SPT counts of soil liquefaction are not applicable to Xinjiang region, will give the risky results. In the new survey data of soil liquefaction evaluation model established of five parameters by the earthquake intensity, the measured SPT counts, datum SPT values, groundwater level, and sand buried depth. The datum SPT values, the influencing coefficients of water and sand depths are gain by a normalized method and by an optimizing method. Establish new formula of soil liquefaction evaluation to the success judging rate is higher, the model shows that constructing reasonable and calculation formula is reliable, can be employed for regional code formulation in Xinjiang area.

Abstract: The serious soil liquefaction phenomenon in Bachu-Jiashi earthquake on 24th February, 2003, which is the most prominent phenomena of sand liquefaction since the Tangshan Great Earthquake in 1976. Based on the earthquake liquefied investigation, inspect SPT and CPT applicability in situ tests. The results show that our country SPT specification and CPT specification of non-liquefied sites evaluation rate is higher than liquefied sites evaluation success rate, the liquefied sites evaluation rate are 88% and 88% respectively, but for liquefied sites evaluation rate are 38% and 55%. The result is tends to danger and the reason need further investigation, so establish a suitable liquefied prediction method should be to the future work in the local area.

Abstract: Take February 24, 2003 the Xinjiang Bachu-Jiashi area liquefication investigation as a foundation, using the SPT count as an indicator of liquefaction decision, liquefied decision methods of sites are considered at domestic and abroad, in which Chinese code liquefied prediction method and Seed-Idriss method are included. The result indicated that our country code and the Seed-Idriss method in liquefied the location prediction success ratios are only 43% and 48%, is in favor of the danger obviously. The reason possibly is the formation of SPT data mainly from the local area, but the Bachu-Jiashi area soil is quite different, therefore is worth the deep research.

Abstract: Cyclic triaxial tests were carried out for remodeled saturated clayey sands with the clay content varying in a relatively wide range from 0% to 40%. In the tests, saturated uniformity clayey sands were obtained by pre-freezing method, i.e. immersing samples in pure water for 12 hours under vacuum, and then, freezing the sample to -15°C for 6 hours. Experimental results indicate that the lowest liquefaction resistance in mixtures occurs when clay contents is of the order of 15%. The ratio of liquefaction shear stresses of the specimens obtained using pre-freezing method are larger than those obtained with the traditional deposit-in-water method.

Abstract: Based on liquefaction survey of 2003 Xinjiang Bachu earthquake of Ms6.8 and in-situ shear wave velocity testing data, the feasibility and applicability of five typical liquefaction evaluation methods which use shear wave velocities as criteria are presented herein. Analysis showed that none of the five liquefaction evaluation methods can provide a satisfactory result in Bachu area. The successful judging rates are only 36% to 64%. The intensity method which is employed to evaluate liquefied and non-liquefied sites in Bachu area provides only 40% successful judging rate, and the method is risky in intensity VII area and conservative in intensity IX area. The critical lines of the five methods deviate greatly from the actual lines. In intensity VII area all the five methods incorrectly misjudge. Further work has to be conducted to research on the soil properties in Bachu area and to establish the regional liquefaction evaluation method in Xinjiang.

Abstract: Cone Penetration Test (CPT) has been conducted at 39 liquefied and non-liquefied sites following the Xinjiang Bachu Ms6.8 earthquake. The current CPT-based liquefaction evaluation method, including Chinese code method, the Robertson method and the Olsen method, was verified by those 39 field test data. The results show that the success verification ratio of Chinese code method, the Robertson method and the Olsen method are relative low by using Bachu earthquake data. Many observed liquefied sites were predicted as non-liquefaction sites, which indicate it is progressive to apply those three methods at Bachu area. The characteristic of soils retrieved from Bachu area is quite differ from that of other areas. An appropriate local method of liquefaction evaluation in Xinjiang region should be developed.