OBTAINING PROBABILISTIC ESTIMATES OF DISPLACEMENT ON A LANDSLIDE DURING FUTURE EARTHQUAKES

The assessment of earthquake triggered landslide hazard may be undertaken using both deterministic and probabilistic techniques. Probabilistic methods have been developed because much of the data can be considered as random variables where parameters such as the angle of internal friction and moisture content do not have a single fixed value but may assume any number of values across a range. This random variability can be modelled by a probability density function (PDF) which describes the relative likeli-hood that a random variable will assume a particular value. Instead of using just the average or expected value of an input parameter, the complete range of possible values can be used to estimate a range of possible outcomes. Thus the probability of a slope being unstable can be obtained rather than a single indicator of stability. Such proba-bilistic analyses allow for the incorporation of the likely variability of each parameter and therefore allow a more intimate assessment of slope stability to be derived. Utilising empirical relationships for calculating earthquake ground motions and associated slope displacement, an investigation was undertaken to identify the contribution that modern simulation techniques could make to the assessment of earthquake-triggered landslides. To achieve this, geotechnical and earthquake data obtained from a deep-seated landslide triggered during the M _w 7.0 Loma Prieta earthquake was used. By incorporating the variability of the geotechnical parameters and the uncertainty in earthquake location the model derived the probabilities associated with increasing amounts of slope displacement during future probable earthquakes. Analysis was undertaken for four of the principal fault segments in the San Francisco Bay area. These estimates were then combined with the occurrence probabilities of the earthquakes to provide temporal estimates of dis-placement for a 30 year period. Results indicated that a M _w 7.0 earthquake located on the Peninsula Segment of the San Andreas fault was most hazardous with a 11% chance of minor slope displacement (≥0.10 m) and a 6% chance of moderate slope displacement (≥0.30 m) within the next 30 years.     

翠华山水湫池及其附近崩塌堆积形成年代探疑

通过对相关史料的分析,论证了翠华山主景区崩塌堆积不可能是唐天宝年间地震诱发山崩形成的。通过实地考察,认为这些崩塌堆积不是同时发生,而是多期崩塌活动的结果,并且崩塌活动又都发生在水湫池被堰塞成湖之后。因此,水湫池不可能是唐代的地震山崩形成的。     

Rapid Diagnosis of Crack Patterns of Masonry Buildings Subjected to Landslide-Induced Settlements by Using the Load Path Method

One of the main difficulties, when dealing with landslide structural vulnerability, is the diagnosis of the causes of the crack pattern. This is also due to the excessive complexity of models based on classical structural mechanics that makes them inappropriate especially when there is the necessity to perform a rapid vulnerability assessment at the territorial scale. This is why in this article a new approach for the rapid diagnosis of crack patterns of masonry buildings subjected to landslide-induced settlements is proposed. This approach is based on the Load Path Method, recently applied to the interpretation of the behavior of masonry buildings subjected to landslide-induced settlements.     

明代三峡新滩地区地质滑坡对交通和社会的影响

本文分析论述了地质滑坡导致局部地区的环境变迁,以及人们为适应环境变迁所做出的种种社会应对。明代嘉靖年间三峡新滩地区的大型滑坡对这里的水路交通造成了严重影响,三峡航路长时间受阻。地方官员曾先后组织人力对新滩地区的崩岸滩石进行疏凿,从而使水路交通在相当程度上得到缓和甚至改观。秋冬季节水位浅涸,三峡航路交通形势险峻时,出入川、楚二地的商旅船只途经该江段时,都不得不进行"盘滩"。专事盘滩成了很多当地居民的专门职业,他们以此谋生,号称"滩子";这同时也形成了三峡新滩地区的季节性繁荣,成为一种独特的三峡经济与三峡景观。历史时期三峡已出现相应的江事预防与赈救措施。