Research On The Method For Evaluating The Earthquake Surface Rupture

Strong earthquake will create ground fracture in suitable condition, and ground fracture will normally cause serious disaster. In engineering construction, the question regarding whether the ground exists the potential risk of ground fracture in earthquake must be answered. So, the assessment for ground fracture in earthquake is one of hot questions in the present field of anti-earthquake for geotechnical engineering. For city disaster planning, engineering construction and exploring occurrence mechanism of earthquake, the research work in this field will have important theoretical significance and engineering application value.In the research of ground fracture in earthquake, three questions are interesting in engineering field. The first one, when strong earthquake happens in seismogenic fault,how big is the possibility of ground fracture? The second one, if ground fracture happens, what is length and width regarding it? The third one, what will earthquake damage come out in covering range? It is very difficult to answer above three questions. Because the cause for ground fracture is controlled by many factors, such as fault activity, magnitude of strong earthquake, focus depth, thickness of ground covering layer, and so on. The cause for ground fracture is uncertain, which is the same as the reason why earthquake happens. For more than one hundred years,academic community has carried on a series of research work in this field, and achieved a plenty of research outcome. Based on summarizing existing research outcome, the article describes the systematic research focused on building up data base of ground fracture, probability computing method of ground fracture, estimation of fracture scale, assessment engineering application of ground fracture. The following major outcomes have been achieved.1. Review on the study of surface rupture of earthquakes. The research progress of ground fracture in earthquake is summarized and concluded systematically. It describes the frontier research in present ground fracture field, and points out existed questions and research work that need to be carried on in this field. There is a certain of reference meaning for research persons who are interested to work.2. Ground fracture data base with engineering character is built. The material of historical and modern earthquake is collected broadly, and historical earthquake material is analyzed and checked seriously, which provide the sign of reliability, make out the input standard for data, and build the most abundant data base of ground fracture in China. The work provides the valuable basic material to carry on researchwork of ground fracture.3. Logistic analysis of regression is introduced to assess the ground fracture in this article. Logistic analysis of regression is used for studying multivariate participation, and it is math analysis model to forecast the probability of occurrence for some affair. Because of independent variable constraint’s weakness, it is applied in engineering, economy and medicine science field broadly. The principle for logistic analysis of regression and suitability of probabilistic forecasting used for ground fracture are introduced in the article. It confirms evaluation factor and grade, applies SPSS software and matlab program for data calculation and significance check, and applies them on example of Wenchuan earthquake and Yutian earthquake, which prove it to be suitable for this method to be applied on probability assessment of ground fracture. Probability expression is achieved in this work for assessing result of ground fracture.4. The relationship between geometrical parameters of surface rupture and magnitude of magnitude is given. Based on existed material, the least square is used to fit the relation between the length, width, horizontal dislocation and vertical dislocation of ground fracture and earthquake grade. The corresponding statistic relation among Chinese mainland, Chinese west, Chinese east, strike-slip fault of Chinese west, normal fault of Chinese west and reverse fault of Chinese west are given individually, and correlation index and residual variance are provided too.Besides, the earthquake magnitude for 6.0-6.4,6.5-6.9,7.0-7.4,7.5-7.9 and occurrence for different fracture length, width, horizontal fault and vertical fault are known by statistics. By above work, the parameter relationship formula between magnitude and ground fracture is built, which is suitable to Chinese mainland area.5. The engineering evaluation method of seismic ground rupture is proposed. The article generally considers the fault activity, the magnitude’s upper limit of fault, and thickness of covering layers. Based on it, the assessment method of probability and geometry for ground fracture is applied in the article. The advices regarding engineering assessment method, risk grade and engineering evaluation of ground fracture are given. This article promotes the combination of active fault research and engineering application, and provides a new way for the application of active fault in engineering site.By building the data base of ground fracture in the article, it provides important base material to carry on the research work further in the field. Logistic analysis method is applied to assess the ground fracture in the article, which achieve probability expression for ground fracture, and enrich the research outcome of ground fracture. The work progress of assessment and statistic geometrical parameterexpression for ground fracture provided in the article has a certain of engineering application value for assessing ground fracture in engineering site.