Research Of Seismic Stability On Earthen Ruins Of Camels City

Earthen ruins are important part of our country immovable cultural relics, there are many national key protecting of earthen ruin in the northwest of China. During thousands of years, earthen ruins, which suffered from various diseases, have different degree safety hazard. Meanwhile, lots of earthen ruins locate in strong earthquake areas and the potential danger of earthquake can't be neglected. Therefore, it is important for seismic protection, disaster prevention and mitigation of earthen ruins to analyze seismic stability and conduct safety evaluation of soil sites.Taking the national key protecting cultural relics in Gaotai of Gansu province—earthen ruins of Camel city as a example, through field investigation, site mapping, references research and other ways, engineering geology and geotechnical engineering of earthen ruins in Camel city are clarified; the disease characteristics and formation mechanism are analyzed. The basic physical parameter and mechanical parameters of earthen ruins are obtained by in-situ dynamic test, indoor test, references research. The calculating parameters are counted utilizing MATLAB numerical software. Through numerical simulation, the following analysis are conducted respectively for earthen ruins in Camel city, including modal analysis, instantaneous dynamics analysis, pseudo dynamic reliability and dynamic reliability analysis, sensitivity, and correlation analysis. Finally, taking the damage threshold as criteria, the generally regular conclusions of stability for earthen ruins in Camel city under seismic load is drawn. The main progress and results of this thesis are specifically as follows:1. The engineering geology and geotechnical engineering conditions including climate, hydrology, geology, seismic activity and so on within the scope of the areas of earthen ruins in Camel city, in addition, the architectural form, disease characteristics, diseases causing and protection status of earthen ruins in Camel city are clarified.2. Conventionally physical parameter and dynamical parameters of building materials of earthen ruins in Camel city are gained, including mode of vibration, natural frequency, wave velocity, elastic modulus, damping ratio, poisson ratio, shear strength and material limit stress, etc.3. Based on the theory of ground vibration energy distribution, the computing efficiency is improved effectively by making use of wavelet optimization method which designs the input ground vibration using wavelet algorithm. Computing method of stochastic finite element method is meliorated on the foundation of ensuring computing precision. Furthermore, the reliability of optimizing calculation method is verified through calculating three-story frame structure by utilizing the mode of decomposition method.4. The modal characteristics of earthen ruins in Camel city with different boundary constraint are calculated. The basic distribution characteristics and changing regularity of displacement field, acceleration and stress field of walls with different intensity, the possible damage mode of earthen ruins and failure condition are analyzed.5. The applicability and advantage of probability and statistics theory method applied to seismic stability research for earthen ruins are comprehensively analyzed. The improved pseudo dynamic reliability and dynamic reliability are introduced to study seismic stability of earthen ruins; the judging method associated test data and computing results for seismic stability of earthen ruins is established.6. Through calculating the correlation and sensitivity of random input and output variables based on certain distribution characteristics, the impact manner and degree of seismic forces, wall density, material Poisson ratio and the relatively independent length of wall on seismic stability properties of earthen ruins is analyzed.This paper is financed by Gansu province scientific support plan (0708NKCF089) funding.